首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   20389篇
  免费   516篇
  国内免费   126篇
化学   12814篇
晶体学   179篇
力学   618篇
综合类   1篇
数学   3353篇
物理学   4066篇
  2022年   216篇
  2021年   306篇
  2020年   334篇
  2019年   371篇
  2018年   279篇
  2017年   260篇
  2016年   563篇
  2015年   443篇
  2014年   487篇
  2013年   1156篇
  2012年   956篇
  2011年   1084篇
  2010年   759篇
  2009年   668篇
  2008年   976篇
  2007年   976篇
  2006年   834篇
  2005年   856篇
  2004年   769篇
  2003年   617篇
  2002年   603篇
  2001年   349篇
  2000年   321篇
  1999年   242篇
  1998年   218篇
  1997年   233篇
  1996年   272篇
  1995年   214篇
  1994年   203篇
  1993年   250篇
  1992年   233篇
  1991年   237篇
  1990年   193篇
  1989年   183篇
  1988年   181篇
  1987年   236篇
  1986年   216篇
  1985年   296篇
  1984年   283篇
  1983年   219篇
  1982年   234篇
  1981年   250篇
  1980年   236篇
  1979年   231篇
  1978年   232篇
  1977年   202篇
  1976年   182篇
  1975年   207篇
  1974年   178篇
  1973年   158篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
In this paper, we adapt the octahedral simplicial algorithm for solving systems of nonlinear equations to solve the linear complementarity problem with upper and lower bounds. The proposed algorithm generates a piecewise linear path from an arbitrarily chosen pointz 0 to a solution point. This path is followed by linear programming pivot steps in a system ofn linear equations, wheren is the size of the problem. The starting pointz 0 is left in the direction of one of the 2 n vertices of the feasible region. The ray along whichz 0 is left depends on the sign pattern of the function value atz 0. The sign pattern of the linear function and the location of the points in comparison withz 0 completely govern the path of the algorithm.This research is part of the VF-Program Equilibrium and Disequilibrium in Demand and Supply, approved by the Netherlands Ministry of Education, Den Haag, The Netherlands.  相似文献   
92.
It is shown in this paper that a pair of points contained in a Fano configuration in a projective plane of odd order cannot induce a Minkowski plane. From this result we derive that no pair of points in the Hughes plane of order 9 can induce a Minkowski plane.  相似文献   
93.
94.
95.
Ion chromatography (IC) can be used to separate radioiodine from fission products and other ionic species in complex reprocessing solution matrices. A preliminary concentration and separation of the radioiodine is performed using a column filled with a platinum-coated copper bed which converts all forms of iodine to iodide and selectively adsorbs the iodide. The separation is completed by employing an anion chromatographic system. The iodide peak aliquot is collected for subsequent radioanalysis by low energy photon spectroscopy. Results indicate quantitative separation and recovery of iodine. The entire system is automated under computer control and is able to handle small (l) and large (500 ml) sample sizes.  相似文献   
96.
Backward proton and pion production is studied in ν and \(\bar v\) charged current interactions in neon. The results are compared with other experiments and theory. The complete backward proton data is compatible with protons produced by reinteractions in the nucleus. However in events with only one proton, muon variables appear correlated to those for the backward proton, as expected by the two-nucleon correlation model.  相似文献   
97.
98.
UV radiation was applied to degrade cyanobacterial hepatotoxin, microcystin-LR in the presence of phycocyanin as a model natural sensitiser. The concentrations of both the toxin and the pigment used in the experiments were higher by several orders of magnitude than found in the environment. The photoreaction parameters were optimised. The process was found to be of limited use for water treatment due to its low efficacy. Additionally, pronounced UV-induced bleaching of the pigment significantly reducing the photoreaction rates of the toxin was observed for the highest UV radiation intensities applied.  相似文献   
99.
Taraba J  Zak Z 《Inorganic chemistry》2003,42(11):3591-3594
An ionic form of diphenyltrichlorophosphorane, namely, diphenyldichlorophosphonium trichloride isolated as a dichlorine solvate (1), was obtained by treating PPh(2)Cl(3) with excess chlorine. The identity of this species was established by single-crystal X-ray analysis and (31)P, (1)H, and (35)Cl NMR and Raman spectra. Bis(diphenyldichlorophosphonium) pentachloroindate (2) was obtained by the reaction of diphenyltrichlorophosphorane with indium trichloride in dichloromethane for comparison purposes. Its identity was determined by (31)P NMR spectra and single-crystal X-ray analysis.  相似文献   
100.
A new algorithm/program has been elaborated for simultaneous processing of different sets of vapour–liquid equilibrium data. The program was tested with six binary hexane + isomeric pentanol systems, each of them measured at three different isobaric conditions and one isothermal system of tert-butyl-methyl-ether + 2-methyl-2-propanol measured at three different temperatures. The correlation uses the maximum likelihood method, taking into account real behaviour of vapour phase. The parameters obtained are valid within the whole temperature range of the data, and are consistent in comparison with those obtained from individual correlations of isobars or isotherms. Results are presented for the Wilson and NRTL equations.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号