检索结果-南通市图书馆

A study on the possible impacts of climate warming on rice production in china

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical sciences 1999年第2期9卷 147-154页

作者： ZHANG Yu WANG fu-tang (Department of Geophysics, Peking University, beijing 100871, china, chinese academy of Meteorological sciences, beijing 100081, china)

Based on climate change scenarios projected from GCMs (GFDL, UKMO and MPI), this study evaluates possible impacts of climate warming on rice production in china using numerical simulation experiments. A stochastic weather generator is used to make the projected climatic change scenarios suitable to the input of crop model, ORYZA1. The results show that the duration of rice growing season will be lengthened by 6-11 days and the accumulated temperature will increase by 200℃.d-330℃.d when CO2 concentration in the atmosphere doubles. The probability of cool injury in reproductive and grain filling period will decrease while that of heat stress will increase. Rice yield will decrease if cultivars and fanning practices are unchanged. If the dates of rice development stages can be maintained unchanged through cultivar adjustment although rice yield in most parts of the areas will decrease, the decrements will be much less than that when cultivars and farming practices are unchanged.

关键词： climate warming impacts rice model GCMs stochastic weather generator

TIME-RESOLVED IR STUDIES OF UV LASER FLASH PHOTOLYSIS OF W(CO)_6 IN C_6H_(12)-CCl_4 AND CCl_4 SOLUTION

在线全文

学校读者我要写书评

暂无评论

chinese Chemical Letters 1991年第11期2卷 885-888页

作者： Pei JIN, Wen Hua WANG, Yan Wei LIU, YONG Bo SHE. and Ke Jian fu Institute of physics, chinese academy of sciences, beijing 100080

Time-resolved IR absorption spectroscopy has been used to atudy the photochemistry of W(CO)_6 in cyclohexane, carbon tetrachloride, and the mixture of carbon tetrachloride and cyelohexane. The reastion of photolytically generated W(CO)_5. C_6H_(12) with CCl_4 was investigated. An intermediate with a lifetime of about 0.5ms, presumably attributed as W(GO)_***_4, was first observed.

关键词： mode CO IN C6H TIME-RESOLVED IR STUDIES OF UV LASER FLASH PHOTOLYSIS OF W CCl4 AND CCl4 SOLUTION UV IR

A New Catalogue of Fine Structures Superimposed on Solar Microwave Bursts

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Astronomy and Astrophysics 2004年第2期4卷 176-188页

作者： Qi-Jun fu, Yi-Hua Yan, Yu-Ying Liu, Min Wang and Shu-Juan WangNational Astronomical Observatories, chinese academy of sciences, beijing 100012 fuqijun2002@*** National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

The 2.6-3.8 GHz, 4.5-7.5 GHz, 5.2-7.6 GHz and 0.7-1.5 GHz componentspectrometers of Solar Broadband Radio Spectrometer (SBRS) started routine observations,respectively, in late August 1996, August 1999, August 1999, and June 2000. They just managed tocatch the coming 23rd solar active maximum. Consequently, a large amount of microwave burst datawith high temporal and high spectral resolution and high sensitivity were obtained. A variety offine structures (FS) superimposed on microwave bursts have been found. Some of them are known, suchas microwave type Ⅲ bursts, microwave spike emission, but these were observed with more detail;some are new. Reported for the first time here are microwave type U bursts with similar spectralmorphology to those in decimetric and metric wavelengths, and with outstanding characteristics suchas very short durations (tens to hundreds ms), narrow bandwidths, higher frequency drift rates andhigher degrees of polarization. Type N and type M bursts were also observed. Detailed zebra patternand fiber bursts at the high frequency were found. Drifting pulsation structure (DPS) phenomenaclosely associated with CME are considered to manifest the initial phase of the CME, andquasi-periodic pulsation with periods of tens ms have been recorded. Microwave 'patches', unlikethose reported previously, were observed with very short durations (about 300 ms), very high fluxdensities (up to 1000 sfu), very high polarization (about 100% RCP), extremely narrow bandwidths(about 5%), and very high spectral indexes. These cannot be interpreted with the gyrosynchrotronprocess. A superfine structure in the form of microwave FS (ZPS, type U), consisting of microwavemillisecond spike emission (MMS), was also found.

关键词： sun: flares sun: radio radiation instrumentation: spectro-graphs

Landscape ecology：the theoretical foundation of sustainable agrolandscape planning and design

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental sciences 1995年第3期7卷 289-296页

作者： Wang Yanglin(Department of Geography, Peking University, beijing 100871 , china)fu Bojie(Research Center for Eco-Environrnental Sceiences, chinese Acaderny of sciences, beijing 100085, china)

Ｌａｎｄｓｃａｐｅｅｃｏｌｏｇｙ：ｔｈｅｔｈｅｏｒｅｔｉｃａｌｆｏｕｎｄａｔｉｏｎｏｆｓｕｓｔａｉｎａｂｌｅａｇｒｏｌａｎｄｓｃａｐｅｐｌａｎｎｉｎｇａｎｄｄｅｓｉｇｎ．ＷａｎｇＹａｎｇｌｉｎ（Ｄｅｐａｒｔｍｅｎｔｏ... 详细信息

Ｌａｎｄｓｃａｐｅｅｃｏｌｏｇｙ：ｔｈｅｔｈｅｏｒｅｔｉｃａｌｆｏｕｎｄａｔｉｏｎｏｆｓｕｓｔａｉｎａｂｌｅａｇｒｏｌａｎｄｓｃａｐｅｐｌａｎｎｉｎｇａｎｄｄｅｓｉｇｎ．ＷａｎｇＹａｎｇｌｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＧｅｏｇｒａｐｈｙ，Ｐｅｋｉｎｇ...

关键词： landscape ecology sustainable development agrolandscape sustainabillty.

Low-Complexity Reconstruction of Covariance Matrix in Hybrid Uniform Circular Array

在线全文

学校读者我要写书评

暂无评论

china Communications 2024年第3期21卷 66-74页

作者： fu Zihao Liu Yinsheng Duan Hongtao Information School Communication University of ChinaBeijing 100024China beijing Institute of Electronic System Engineering Beijing 100854China School of Electronic and Information Engineering Beijing Jiaotong UniversityBeijing 100044China beijing Radio Monitoring Station of State Radio Monitoring Center(SRMC) Beijing 100037China

Spatial covariance matrix(SCM) is essential in many multi-antenna systems such as massive multiple-input multiple-output(MIMO). For multi-antenna systems operating at millimeter-wave bands, hybrid analog-digital structure has been widely adopted to reduce the cost of radio frequency *** this situation, signals received at the antennas are unavailable to the digital receiver, and as a consequence, traditional sample average approach cannot be used for SCM reconstruction in hybrid multi-antenna systems. To address this issue, beam sweeping algorithm(BSA) which can reconstruct the SCM effectively for a hybrid uniform linear array, has been proposed in our previous works. However, direct extension of BSA to a hybrid uniform circular array(UCA)will result in a huge computational burden. To this end, a low-complexity approach is proposed in this paper. By exploiting the symmetry features of SCM for the UCA, the number of unknowns can be reduced significantly and thus the complexity of reconstruction can be saved accordingly. furthermore, an insightful analysis is also presented in this paper, showing that the reduction of the number of unknowns can also improve the accuracy of the reconstructed SCM. Simulation results are also shown to demonstrate the proposed approach.

关键词： hybrid array millimeter-wave spatial covariance matrix uniform circular array

Effect of Long-Term Application of Chemical Fertilizers on Microbial Biomass and functional Diversity of a Black Soil

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2008年第6期18卷 801-808页

作者： KONG Wei-Dong ZHU Yong-Guan fu Bo-Jie HAN Xiao-Zeng ZHANG Lei HE Ji-Zheng Research Center for Eco-Environmental sciences Chinese Academy of Sciences Beijing 100085 （China） Northeast Institute of Geography and Agricultural Ecology Chinese Academy of Sciences Harbin 150040 （China） Institute of Microbiology Chinese Academy of Sciences Beijing 100080 （China）

An experiment with seven N, P, K-fertilizer treatments, i.e., control (no fertilizer), NP, NK, PK, NPK, NP2K, and NPK2 where P2 and K2 indicate double amounts of P and K fertilizers respectively, was conducted to examine the effect of long-term continuous application of chemical fertilizers on microbial biomass and functional diversity of a black soil (Udoll in the USDA Soil Taxonomy) in Northeast china. The soil microbial biomass C ranged between 94 and 145 mg kg-1, with the NK treatment showing a lower biomass; the functional diversity of soil microbial community ranged from 4.13 to 4.25, with an increasing tendency from control to double-fertilizer treatments, and to triple-fertilizer treatments. The soil microbial biomass, and the microbial functional diversity and evenness did not show any significant differences among the different fertilizer treatments including control, suggesting that the long-term application of chemical fertilization would not result in significant changes in the microbial characteristics of the black soil.

关键词： Biolog black soil chemical fertilizer microbial biomass microbial functional diversity

Direct methods of solving crystal structures

在线全文

学校读者我要写书评

暂无评论

Direct methods of solving crystal structures

Constraints of authigenic carbonates on trace elements (Sr,Mg) of lacustrine ostracod shells in paleoenviron-ment reconstruction and its mechanism

CCAST“先进高分辨电子显微学—理论和应用”研讨会

作者： Fan Hai-fu Institute of physics. chinese academy of sciences, beijing 100080

＜正＞ Direct methods solve crystal structures by finding phases of a set of structure factors directly from thecorresponding structure-factor *** philosophy is that the phase information,*** value ofinitial phases of diffraction waves from the sample crystal,has not lost in the conventional diffractionexperiment,but just hidden among the measured structure-factor *** from which the phasescan be *** reason is as *** the structure factory expression

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Science china Earth sciences 2008年第5期51卷 654-664页

作者： HU Guang1,2, JIN ZhangDong1 & ZHANG Fei3 1 State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, chinese academy of sciences, Xi’an 710075, china 2 Graduate University of the chinese academy of sciences, beijing 100049, china 3 College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing 210095, china State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China Graduate University of the chinese academy of sciences Beijing 100049 China College of Resources and Env

Molar ratios of Mg/Ca and Sr/Ca were measured in two species of ostracod shells preserved in the upper core (15–55 m) of the Hequing Basin in Yunnan Province, southwest china. By correlating the molar ratios between Mg/Ca and Sr/Ca and comparing them with Sr concentrations of the sediments, we suggested that: (1) the molar Mg/Ca and Sr/Ca ratio variations in respective ostracod primo reflected the changes in its ambient water composition and ecology; (2) the molar Sr/Ca ratios responded better to the salinity change linearly than Mg/Ca without aragonite precipitation in the system, and otherwise there was no linear relation between them; and (3) the molar Sr/Ca ratios were mainly controlled by salinity and authigenic carbonate precipitation, whereas the molar Mg/Ca ratios were related to both salinity and temperature. In fact, the rate of ostracod growth owing to temperature controls the fluctuation of Mg/Ca in shells. Here, more attentions should be paid to the constraint of authigenic mineral precipitation processes on the trace elements in ostracod shells and to the correlation between these trace elements in biogenic carbonates and compositions of the sediments in systems and in future in vitro experiments.

关键词： ostracod shell molar Sr/Ca ratio molar Mg/Ca ratio environmental response Heqing Basin

Evaluation of 3D crustal seismic velocity models in southwest china:Model performance,limitation,and prospects

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2024年第2期67卷 604-619页

作者： Xin WANG Ling CHEN Qi-fu CHEN Key Laboratory of Earth and Planetary physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China College of Earth and Planetary sciences University of Chinese Academy of SciencesBeijing100049China State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China

Southwest china is a tectonically and seismically active region,witnessing strong deformation due to the collision between the Indian and Eurasian *** the subsurface velocity structure of this region is thus important in understanding the tectonics and geodynamic processes of continental collision and in mitigating seismic *** studies have provided various 3D seismic velocity models in southwest ***,discrepancies exist among these models,and less effort has been made to quantify the reliability and accuracy of these existing velocity *** this study,we use regional 3D waveform simulation to evaluate the performance of various regional crustal 3D velocity models in reproducing observed *** particularly focus on two recent earthquake sequence in the region,the 2021 Yunnan Yangbi MS_(6.4) earthquake sequence and the 2022 Sichuan Luding MS_(6.8) earthquake *** tested 3D velocity models include the Southwest china Community Velocity model V1.0,the Unified Seismic Tomography Models for Continental china Lithosphere V2.0,the adjoint full waveform tomography model of the crustal and upper mantle beneath Eastern Tibetan Plateau,and the shallow seismic structure model beneath continental *** results show that the tested 3D velocity models generally capture well long-period(full-waveform tomography model shows a slighter better performance than the other models,especially for the body-waves,highlighting the advantages

关键词： Southwest china Seismic tomography models Shallow Structures Waveform simulation Model evaluation