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Spatial Characteristics of Thomson Scattering Spectra in Laser and Magnetic Fields
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作者 赵丽 陈之景 +1 位作者 桑海波 谢柏松 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第7期34-38,共5页
Spatial characteristics of Thomson scattering spectra are studied for an electron moving in the circularly polarized laser field in the presence of a strong uniform magnetic field. The results show that the angular di... Spatial characteristics of Thomson scattering spectra are studied for an electron moving in the circularly polarized laser field in the presence of a strong uniform magnetic field. The results show that the angular distributions of the spectra with respect to the azimuthal and polar angles exhibit different symmetries, respectively, which depend on the fields and electron parameters sensitively and significantly. Moreover, for relatively large parameters such as high laser intensity, high magnetic resonance parameter as well as large initial momentum of electron, the two lobes in spectra tend to the laser-propagating direction so that the radiation can be collimated in the forward direction. Furthermore, an important finding is that by choosing the appropriate fields and initial momentum of electron, the high frequency part of the Thomson scattering spectra can reach the frequency range of soft x-ray,in which a high radiation power per solid angle as ~10^11 a.u. can be obtained. 展开更多
关键词 SPATIAL characteristics STUDIED for an ELECTRON can be obtained
Pressure-Induced Ionic-Electronic Transition in BiVO4
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作者 吕舒鹏 王佳 +5 位作者 张国召 王宇飞 王敏 刘才龙 高春晓 韩永昊 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第7期86-89,共4页
Electrical transport properties of bismuth vanadate(BiVO4) are studied under high pressures with electrochemical impedance spectroscopy. A pressure-induced ionic-electronic transition is found in BiVO4. Below 3.0 GPa,... Electrical transport properties of bismuth vanadate(BiVO4) are studied under high pressures with electrochemical impedance spectroscopy. A pressure-induced ionic-electronic transition is found in BiVO4. Below 3.0 GPa, BiVO4 has ionic conduction behavior. The ionic resistance decreases under high pressures due to the increasing migration rate of O2-ions. Above 3.0 GPa the channels for ion migration are closed. Transport mechanism changes from the ionic to the electronic behavior. First-principles calculations show that bandgap width narrows under high pressures, causing the continuous decrease of electrical resistance of BiVO4. 展开更多
关键词 ELECTRICAL TRANSPORT properties STUDIED under high pressures ELECTRICAL resistance of BIVO4
Do Your Students Notice Anything?(III) 预览
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作者 Jeremy Harmer 《基础教育外语教学研究》 2019年第3期30-32,共3页
So where are we now? It seems necessary to draw breath again and see where we have got to. Among the conclusions we are obliged to draw from the above discussion (and from our observation and reading as both classroom... So where are we now? It seems necessary to draw breath again and see where we have got to. Among the conclusions we are obliged to draw from the above discussion (and from our observation and reading as both classroom practitioners and classroom-based theorists at whatever level) are the following: Some language is clearly acquired subconsciously without any conscious attention being drawn to it either by the learner or by some other agent (such as the teacher). No other explanation will account for the fact that competent language learners seem to know things which there is no evidence of them ever having studied or thought about. 展开更多
关键词 DRAW BREATH classroom-based theorists STUDIED or THOUGHT about
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幸福
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《英语角》 2019年第1期30-31,46共3页
"Happiness is U-shaped.We are happier at the start and end of our lives but hit a slump when we are middle-aged,"scientists from England and America say.They have studied the information on the mental health... "Happiness is U-shaped.We are happier at the start and end of our lives but hit a slump when we are middle-aged,"scientists from England and America say.They have studied the information on the mental health of two million people from 80 countries. 展开更多
关键词 MENTAL happier INFORMATION START STUDIED
《食品工艺学》研究型实验教学方法的探索与实践 预览 被引量:5
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作者 李秋红 《科技信息》 2008年第36期 10,6,共2页
《食品工艺学》是食品生物工程专业的一门理论性和实践性都非常强的专业课。在教学质量工程和创新型人才培养的背景下,对该课程实验方法进行了研究型实验教学改革:在教学过程中,用基础知识去指导学生选题、制定实验方案、实验方案实... 《食品工艺学》是食品生物工程专业的一门理论性和实践性都非常强的专业课。在教学质量工程和创新型人才培养的背景下,对该课程实验方法进行了研究型实验教学改革:在教学过程中,用基础知识去指导学生选题、制定实验方案、实验方案实施、实验结果的表迭,同时,又注意从实验结果中去验证所掌握的理论知识,取得了非常好的效果。 展开更多
关键词 食品工艺学 研究型 实验教学 改革
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建筑环境与设备工程专业课程体系的研究与实践 预览 被引量:15
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作者 张昌 郑万兵 +1 位作者 汤文华 汪秀清 《高等建筑教育》 2008年第3期 35-40,共6页
文章在现代高等工程教育理念的指导下,全面研究了建筑环境与设备工程专业的课程体系,系统总结了专业人才培养中各个教学环节的教学经验,同时还示范性地提出了专业核心课程的教学要点。
关键词 建筑环境与设备 课程体系 研究 实践
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《诗经》出土文献与文学研究 预览 被引量:1
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作者 于淑娟 《北方论丛》 北大核心 2007年第2期 6-9,共4页
出土文献研究为文学研究提供了宝贵的资料,文字的考证训诂是文学研究的基础。在出土文献研究中引入文学解读方法,可帮助厘定出土文献与已有资料的异文考辨。此外,出土文献研究与文学研究在治学方法上都注重文化背景,出土文献研究借... 出土文献研究为文学研究提供了宝贵的资料,文字的考证训诂是文学研究的基础。在出土文献研究中引入文学解读方法,可帮助厘定出土文献与已有资料的异文考辨。此外,出土文献研究与文学研究在治学方法上都注重文化背景,出土文献研究借助文化考察对文字作出新的训诂,为文学研究提供新的视角和空间。 展开更多
关键词 诗经 出土文献研究 文学研究 《金石简帛诗经研究》
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The atomic structure and the properties of Ununbium (z=112) and Mercury (Z=80)
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作者 LI JiGuang 《中国科学:物理学、力学、天文学英文版》 SCIE EI CAS 2007年第6期707-715,共9页
  A super heavy element Uub (Z = 112) has been studied theoretically in conjunction with rela-tivistic effects and the effects of electron correlations. The atomic structure and the oscillator strengths of low-lying...   A super heavy element Uub (Z = 112) has been studied theoretically in conjunction with rela-tivistic effects and the effects of electron correlations. The atomic structure and the oscillator strengths of low-lying levels have been calculated, and the ground states have also been determined for the singly and doubly charged ions. The influence of relativity and correlation effects to the atomic properties of such a super heavy element has been investigated in detail. The results have been compared with the properties of an element Hg. Two energy levels at wave numbers 64470 and 94392 are suggested to be of good candidates for experimental observations.…… 展开更多
关键词 super HEAVY element ATOMIC structure relativistic effects electron correlation effects MCDF method A super HEAVY ELEMENT Uub (Z = 112) has been studied theoretically in conjunction with rela-tivistic EFFECTS and the EFFECTS of electron correlations. The ATOMIC structure and the oscillator strengths of low-lying levels HAVE been calculated and the ground states HAVE also been determined for the singly and doubly charged ions. The influence of relativity and correlation EFFECTS to the ATOMIC properties of such a super HEAVY ELEMENT has been investigated in detail. The results HAVE been compared with the properties of an ELEMENT Hg. Two energy levels at wave numbers 64470 and 94392 are suggested to be of good candidates for experimental observations.……
Valence electronic structure of tantalum carbide and nitride 被引量:1
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作者 FAN ChangZeng 《中国科学:物理学、力学、天文学英文版》 SCIE EI CAS 2007年第6期737-741,共5页
  The valence electronic structures of tantalum carbide (TaC) and tantalum nitride (TaN) are studied by using the empirical electronic theory (EET). The results reveal that the bonds of these compounds have covalent...   The valence electronic structures of tantalum carbide (TaC) and tantalum nitride (TaN) are studied by using the empirical electronic theory (EET). The results reveal that the bonds of these compounds have covalent, metallic and ionic characters. For a quantitative analysis of the relative strength of these components, their ionicities have been calculated by implanting the results of EET to the PVL model. It has been found that the ionicity of tantalum carbide is smaller than that of tantalum nitride. The EET results also reveal that the covalent electronic number of the strongest bond in the former is larger than that of the latter. All these suggest that the covalent bond of TaC is stronger than that of TaN, which coincides to that deduced from the first-principles method.…… 展开更多
关键词 TaC TaN VALENCE ELECTRONIC structure ionicity The VALENCE ELECTRONIC structures of TANTALUM carbide (TaC) and TANTALUM NITRIDE (TaN) are studied by using the empirical ELECTRONIC theory (EET). The results reveal that the bonds of these compounds have covalent metallic and ionic characters. For a quantitative analysis of the relative strength of these components their ionicities have been calculated by implanting the results of EET to the PVL model. It has been found that the ionicity of TANTALUM carbide is smaller than that of TANTALUM nitride. The EET results also reveal that the COVALENT ELECTRONIC number of the strongest bond in the former is larger than that of the latter. All these suggest that the COVALENT bond of TaC is stronger than that of TaN which coincides to that deduced from the first-principles method.……
首位留学美英的医生黄宽 被引量:3
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作者 刘泽生 《中华医史杂志》 CAS 2006年第3期 169-172,共4页
黄宽是我国第一位留学美国,学习西医于英国的医生。在美国盂松学校学习基础科学知识,两年后在英国爱丁堡大学接受医学教育并获得医学学位。他是我国早期杰出的外科医生。在传播西方医学方面作出重要贡献,在当时他被称为好望角以东最... 黄宽是我国第一位留学美国,学习西医于英国的医生。在美国盂松学校学习基础科学知识,两年后在英国爱丁堡大学接受医学教育并获得医学学位。他是我国早期杰出的外科医生。在传播西方医学方面作出重要贡献,在当时他被称为好望角以东最负盛名之良外科。他的业绩自当永垂中国医学史。 展开更多
关键词 黄宽 留学 医生 美英
An example of earthquake nucleation of the strong continental earthquakes 被引量:1
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作者 CHEN Xue-zhong 《地震学报:英文版》 CSCD 2001年第2期 225-229,共5页
  Introduction    The study on earthquake nucleation is widely concerned by seismologists in the world. The experimental and theoretical studies indicate that earthquakes should be preceded by quasi-static slip w...   Introduction    The study on earthquake nucleation is widely concerned by seismologists in the world. The experimental and theoretical studies indicate that earthquakes should be preceded by quasi-static slip within a nucleation zone (Oh-naka, 1992; Dodge, Beroza, 1995; Dodge, et al, 1996; Ohnaka, Kuwahara, 1990; Yamashita, Ohnaka, 1991). The earthquake nucleation process means a transition from quasi-static to quasi-dynamic rupture process, and it itself is a short-term precursor. Immediate foreshocks are local dynamic instabilities that occur during the transition from the quasi-static to the quasi-dynamic nucleation of the dynamic instability (Ohnaka, 1992). According to the recent theoretical study, immediate foreshocks can be regarded as the localized fractures accompanied by the quasi-static nucleation process of a large earthquake (Shibazaki, Matsu'ura, 1995). Therefore, foreshocks could occur during the nucleation process. The nucleation of earthquakes can be illuminated through analyzing foreshock activity in detail. Detection of the nucleation process by means of a foreshock study is a potential tool for earthquake predic-tion. The nucleation process of Izu peninsula earthquake with M=7.0 on January 14, 1978 is revealed by Ohnaka with foreshock activities. It was observed that the nucleation zone indicated by foreshocks grew at a rate of 1~40 cm/s before reaching a diameter of 10 km. The depths of foreshocks do not change much more, keep within 10 km. Recently, Hurukawa have studied the nucleation process of Off-Etorofu earthquake with MW=7.9 on December 3, 1995. The results show distinctly the nucleation process before the main shock. In the nucleation process, rupture started at the deepest point of the foreshock area, and then propagated to the shallow depth with the apparent ve-locity of 5~20 cm/s (Hurukawa, 1998). Rastogi and Mandal (1998) studied the rupture nucleation process of five Koyna medium-sized main shocks using the time-space patterns of foreshocks. They found that the nuc 展开更多
关键词 strong continental EARTHQUAKE FORESHOCK EARTHQUAKE NUCLEATION 分类号:P315.75 文献标识码:A 文章编号:1000-9116(2001)01-0225-05 Introduction The study on EARTHQUAKE NUCLEATION is widely concerned by seismologists in the world. The experimental and theoretical studies indicate that earthquakes should be preceded by QUASI-STATIC slip within a NUCLEATION zone (Oh-naka 1992 Dodge Beroza 1995 Dodge et al 1996 Ohnaka Kuwahara 1990 Yamashita Ohnaka 1991). The EARTHQUAKE NUCLEATION PROCESS means a transition from QUASI-STATIC to quasi-dynamic rupture process and it itself is a short-term precursor. Immediate FORESHOCKS are local dynamic instabilities that occur during the transition from the QUASI-STATIC to the quasi-dynamic NUCLEATION of the dynamic instability (Ohnaka 1992). According to the recent theoretical study immediate FORESHOCKS can be regarded as the localized fractures accompanied by the QUASI-STATIC NUCLEATION PROCESS of a large EARTHQUAKE (Shibazaki Matsu'ura 1995). Therefore FORESHOCKS could occur during the NUCLEATION process. The NUCLEATION of earthquakes can be illuminated through analyzing FORESHOCK activity in detail. Detection of the NUCLEATION PROCESS by means of a FORESHOCK study is a potential tool for EARTHQUAKE predic-tion. The NUCLEATION PROCESS of Izu peninsula EARTHQUAKE with M=7.0 on January 14 1978 is revealed by Ohnaka with FORESHOCK activities. It was observed that the NUCLEATION zone indicated by FORESHOCKS grew at a rate of 1~40 cm/s before reaching a diameter of 10 km. The depths of FORESHOCKS do not change much more keep within 10 km. Recently Hurukawa have studied the NUCLEATION PROCESS of O
ULF electromagnetic precursors before the 1999 Jiji, Taiwan, earthquake and the comparison with results of simulating experiments 被引量:1
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作者 QIAN Shu-qing 《地震学报:英文版》 CSCD 2001年第3期 342-348,共7页
There are many reports about the abnormal electromagnetic signals observed before great earthquakes. In particular, the signals of electromagnetic anomalies before the Hyogo-Ken Nanbu, Japan, MS=7.2 earthquake on Janu... There are many reports about the abnormal electromagnetic signals observed before great earthquakes. In particular, the signals of electromagnetic anomalies before the Hyogo-Ken Nanbu, Japan, MS=7.2 earthquake on January 17, 1995 (Hayakawa, et al, 1996) and those before the Loma Prieta, USA, MS=7.1 earthquake on October 19, 1989 (Fraser-Smith, et al, 1990) are especially remarkable. However, what the above authors reported are only the phenomena of one or two observatories. In order to confirm this phenomenon, the authors studied the results obtained by nine observatories in the southeast coastal areas of Chinese mainland within a range of 256~858 km to the epicenter of the 1999 Jiji, Taiwan, earthquake using instruments of the same type (the ULF/VLF electromag-netic wave observation system). By summarizing the data for the three months up to the time of earthquake occur-rence, the authors obtained the regional distribution of the signals of electromagnetic anomalies before the earth-quake and their features in the time domain and frequency domain. 展开更多
关键词 Jiji EARTHQUAKE experiment of rock fracture under compression ULF ELECTROMAGNETIC precursors mechanism of production and propagation 分类号:P319 文献标识码:A 文章编号:1000-9116(2001)03-0342-07 There ARE many reports about the abnormal ELECTROMAGNETIC SIGNALS observed BEFORE great earthquakes. In particular the SIGNALS of ELECTROMAGNETIC anomalies BEFORE the Hyogo-Ken Nanbu Japan MS=7.2 EARTHQUAKE on January 17 1995 (Hayakawa et al 1996) and those BEFORE the Loma Prieta USA MS=7.1 EARTHQUAKE on October 19 1989 (Fraser-Smith et al 1990) ARE especially remarkable. However what the above authors reported ARE only the phenomena of one or two observatories. In order to confirm this phenomenon the authors studied the results obtained by nine OBSERVATORIES in the southeast coastal areas of Chinese mainland within a range of 256~858 km to the epicenter of the 1999 Jiji Taiwan EARTHQUAKE using instruments of the same type (the ULF/VLF electromag-netic wave observation system). By summarizing the data for the three months up to the time of EARTHQUAKE occur-rence the authors obtained the regional distribution of the SIGNALS of ELECTROMAGNETIC anomalies BEFORE the earth-quake and their features in the time domain and frequency domain.……
Oxide and Sulfide Dispersive Precipitation in Ultra-low Carbon Steels 预览
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作者 Delu Liu 《北京科技大学学报:英文版》 CSCD 2001年第4期 314-315,共2页
  The microstructure and mechanical properties of low carbon steel strips produced by the CSP process have been studied. Samples for the present study were cut from strips with thickness 4mm immediately after coilin...   The microstructure and mechanical properties of low carbon steel strips produced by the CSP process have been studied. Samples for the present study were cut from strips with thickness 4mm immediately after coiling in a CSP steel plant. Compositions (mass fraction/%) ofthem (sample CSP-33) is shown as follows: C--0.062; Si--0.11; S--0.002; P--0.013; Mn--0.30; Cu--0.16; Al--0.032; Alsol--0.029; Aloxy--0.002 7; O--0.0036; N--0.0076.   …… 展开更多
关键词 OXIDE PRECIPITATION SULFIDE low carbon STEEL CSP strip electron diffraction CLC Number:TG14 Document ID:B The microstructure and mechanical properties of low carbon STEEL STRIPS produced by the CSP process have been studied. Samples for the present study were cut from STRIPS with thickness 4mm immediately after coiling in a CSP STEEL plant. Compositions (mass fraction/%) ofthem (sample CSP-33) is shown as follows: C--0.062 Si--0.11 S--0.002 P--0.013 Mn--0.30 Cu--0.16 Al--0.032 Alsol--0.029 Aloxy--0.002 7 O--0.0036 N--0.0076. ……
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红鲫染色体组型的研究 预览 被引量:3
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作者 吴端生 《长沙水电师院自然科学学报》 1993年第3期 270-274,共5页
采用肾细胞染色体直接制片法及Levan提出的标准,研究了红鲫的染色体组型。红鲫肾细胞染色体数目2n=100,核型公式为22m+30 sm+24 st+24t。尚未发现雌雄间有异型性染色体及特殊标志染色体。
关键词 红鲫 染色体组型
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A STUDY ON THE INFLUENCE OF CITRATE SODIUM, NaCl, KCl ON THE PE LIQUID CRYSTALLINE STRUCTURE BY MEANS OF THE SMALL ANGLE X-RAY SCATTERING
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作者 孙润广 王子浩 +1 位作者 王德华 张静 《中国科学通报:英文版》 SCIE 1992年第8期651-656,共6页
关键词 Phosphatidylethanolamine abbreviated as PE belongs to phospholipids. It is one of the important materials which forms BIOLOGICAL membranes and plays a very important role in maintaining the STRUCTURE and FUNCTION of BIOLOGICAL membrane system. Therefore people HAVE been trying to explore the relations between its STRUCTURE and FUNCTION in various ways. Since 1970’s the phospholipid-water SYSTEM HAVE been widely and profoundly studied by
RECIPROCALLY TOPOGRAPHIC PROJECTIONS BETWEEN THE OPTIC TECTUM AND NUCLEUS ISTHMI IN THE TOAD 被引量:1
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作者 王荫亭 颜坤 王书荣 《科学通报:英文版》 SCIE EI 1983年第1期139-140,
关键词 In this letter neuronal projections BETWEEN the TOAD (Bufo BUFO gargarizans) optic toctum and nucleus isthmi (NI) are studied by means of horseradish peroxidase (HRP) method and HRP-labeled tectal and isthmic cells are classified.After surgical operation the animal was fixed in a stereotaxic apparatus. HRP (Sigma VI) was iontophorezed into different sites over superficial layers of the tectum in 53 TOADS and throughout NI in 13 TOADS one injection each animal. After their survival of 2—8 days at 16—20℃ using HRP histochemical method the injected and labeled sites as well as the morphology of the labeled cells were shown.The results indicate that reciprocally topographic projections exist BETWEEN the TOAD optictectum and its ipsilateral NI i. e. an isthmic
中国法科学生留学德国四十年的回顾与展望--基于博士学位论文的考察
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作者 卜元石 《法学研究》 CSSCI 北大核心 2019年第2期3-22,共20页
基于对中国留德法学博士学位论文的考察,可以简要回顾改革开放四十年来中国法科学生留学德国的基本情况。四十年来,中国法科学生留德数量不断增加,在攻读博士学位的专业分布以及博士论文的选题方面有一定的规律可循,并且一定程度上存在... 基于对中国留德法学博士学位论文的考察,可以简要回顾改革开放四十年来中国法科学生留学德国的基本情况。四十年来,中国法科学生留德数量不断增加,在攻读博士学位的专业分布以及博士论文的选题方面有一定的规律可循,并且一定程度上存在就读学校集中以及博士论文指导教师集中的现象。中国留德法学博士是中德法学学术交流的重要使者,其研究成果以德语发表,惠及德语区读者;其归国后若从事学术研究,亦有机会将其研究成果通过中文出版物传播,对于中国相关法学学科视野的拓展、知识的丰富都起到了一定的推动作用。对于中国留学生在德攻读法学博士学位期间以及归国后重新融入国内学术圈所面临的困难的反思表明,有必要从个人与国家两个层面深入思考如何更好地利用留学德国的契机,培养中国的法律人才,并使之归国后更好地发挥才能。 展开更多
关键词 留学德国 法学博士学位论文 德国法 法教义学 留学国别主义
一种解决连续空间问题的真实在线自然梯度AC算法 预览 被引量:1
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作者 朱斐 朱海军 +2 位作者 刘全 陈冬火 伏玉琛 《软件学报》 CSCD 北大核心 2018年第2期267-282,共16页
策略梯度作为一种能够有效解决连续空间决策问题的方法得到了广泛研究,但由于在策略估计过程中存在较大方差,因此,基于策略梯度的方法往往受到样本利用率低、收敛速度慢等限制.针对该问题,在行动者-评论家(actor-critic,简称AC)算法... 策略梯度作为一种能够有效解决连续空间决策问题的方法得到了广泛研究,但由于在策略估计过程中存在较大方差,因此,基于策略梯度的方法往往受到样本利用率低、收敛速度慢等限制.针对该问题,在行动者-评论家(actor-critic,简称AC)算法框架下,提出了真实在线增量式自然梯度AC(true online incremental natural actor-critic,简称TOINAC)算法.TOINAC算法采用优于传统梯度的自然梯度,在真实在线时间差分(true online time difference,简称TOTD)算法的基础上,提出了一种新型的前向观点,改进了自然梯度行动者-评论家算法.在评论家部分,利用TOTD算法高效性的特点来估计值函数;在行动者部分,引入一种新的前向观点来估计自然梯度,再利用资格迹将自然梯度估计变为在线估计,提高了自然梯度估计的准确性和算法的效率.将TOINAC算法与核方法以及正态策略分布相结合,解决了连续空间问题.最后,在平衡杆、Mountain Car以及Acrobot等连续问题上进行了仿真实验,验证了算法的有效性. 展开更多
关键词 策略梯度 自然梯度 行动者-评论家 真实在线TD 核方法
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烤烟井窖式移栽水肥精准控施器的研制与应用效果研究 预览
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作者 闫凯 张伟 +4 位作者 王大伟 李强 高阳 贺永楷 姜鹏超 《现代农业科技》 2018年第4期20-20,25共2页
为解决烤烟井窖式移栽传统方法进行水肥浇施单株用量不均衡、烟株大田不整齐,并且用工多、劳动强度大等问题,2016年开展水肥精准控施施器的研制与应用效果研究。结果表明,该装置能够根据具体需求,精准调控水肥溶液的浇施量,每穴用量均... 为解决烤烟井窖式移栽传统方法进行水肥浇施单株用量不均衡、烟株大田不整齐,并且用工多、劳动强度大等问题,2016年开展水肥精准控施施器的研制与应用效果研究。结果表明,该装置能够根据具体需求,精准调控水肥溶液的浇施量,每穴用量均匀一致;可降低劳动强度,节省用工,每个作业小组可减少用工20%左右;且提高烟叶大田整齐度,同田成熟落黄一致。 展开更多
关键词 烤烟 井窖式移栽 水肥精准控施器 整齐度
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Meteorological drought features in northern and northwestern parts of Mexico under different climate change scenarios
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作者 Carlos ESCALANTE-SANDOVAL Pedro NUNEZ-GARCIA 《干旱区科学:英文版》 SCIE CSCD 2017年第1期65-75,共11页
Meteorological drought has been an inevitable natural disaster throughout Mexican history and the northern and northwestern parts of Mexico(i.e., the studied area), where the mean annual precipitation(MAP) is less tha... Meteorological drought has been an inevitable natural disaster throughout Mexican history and the northern and northwestern parts of Mexico(i.e., the studied area), where the mean annual precipitation(MAP) is less than 500 mm, have suffered even more from droughts in the past. The aim of this study was to conduct a meteorological drought analysis of the available MAP data(1950–2013) from 649 meteorological stations selected from the studied area and to predict the drought features under the different IPCC-prescribed climate change scenarios. To determine the long-term drought features, we collected 1×10~4 synthetic samples using the periodic autoregressive moving average(PARMA) model for each rainfall series. The simulations first consider the present prevailing precipitation conditions(i.e., the average from 1950 to 2013) and then the precipitation anomalies under IPCC-prescribed RCP 4.5 scenario and RCP 8.5 scenario. The results indicated that the climate changes under the prescribed scenarios would significantly increase the duration and intensity of droughts. The most severe impacts may occur in the central plateau and in the Baja California Peninsula. Thus, it will be necessary to establish adequate protective measures for the sustainable management of water resources in these regions. 展开更多
关键词 干旱特征 气候变化 气象干旱 墨西哥 西北部 年平均降水量 IPCC 加利福尼亚
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