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   1051篇
  免费   30篇
  国内免费   3篇
化学   702篇
晶体学   20篇
力学   5篇
数学   215篇
物理学   142篇
  2021年   18篇
  2020年   11篇
  2019年   13篇
  2018年   16篇
  2017年   21篇
  2016年   37篇
  2015年   46篇
  2014年   29篇
  2013年   65篇
  2012年   56篇
  2011年   53篇
  2010年   42篇
  2009年   38篇
  2008年   46篇
  2007年   52篇
  2006年   37篇
  2005年   39篇
  2004年   25篇
  2003年   16篇
  2002年   22篇
  2001年   7篇
  2000年   14篇
  1999年   13篇
  1997年   14篇
  1996年   12篇
  1995年   7篇
  1994年   6篇
  1993年   11篇
  1992年   11篇
  1991年   12篇
  1990年   8篇
  1989年   7篇
  1987年   10篇
  1986年   8篇
  1985年   9篇
  1984年   7篇
  1983年   12篇
  1982年   9篇
  1981年   6篇
  1980年   9篇
  1979年   9篇
  1978年   9篇
  1977年   15篇
  1976年   7篇
  1975年   17篇
  1974年   13篇
  1966年   9篇
  1958年   23篇
  1957年   10篇
  1956年   6篇
排序方式: 共有1084条查询结果,搜索用时 171 毫秒
51.
Homopolymerization of acrylamide as well as that of methyl methacrylate and the copolymerization of acrylamide with methyl methacrylate and/or styrene in inverse microemulsion toluene/water 10: 1 by weight have been studied. Water-soluble ammonium peroxodisulfate, partially water-soluble 2,2′-azobisisobutyronitrile, and oil-soluble dibenzoyl peroxide were used for initiation of these polymerizations at 60°C. Redox initiation system consisting of ammonium peroxodisulfate and tetramethylethylenediamine has been used for an effective initiation of the reactions studied at 30°C. Polymerizations in inverse microemulsions were found start in the interlayer oil macrophase/water microphase. The initial rates of copolymerizations reactions studied depended only on the comonomer mixture composition. The type of the initiator used affected only the exhibited inhibition period.  相似文献   
52.
The administration of toxin-specific therapy in snake envenoming is predicated on improved diagnostic techniques capable of detecting specific venom toxins. Various serological tests have been used in detecting snakebite envenoming. Comparatively, enzyme-linked immunosorbent assay (ELISA) has been shown to offer a wider practical application. We report an inhibition ELISA for detecting three-finger toxin (3FTx) proteins in venoms of African spitting cobras. The optimized assay detected 3FTxs in N. ashei (including other Naja sp.) venoms, spiked samples, and venom-challenged mice samples. In venoms of Naja sp., the assay showed inhibition, implying the detection of 3FTxs, but showed little or no inhibition in non-Naja sp. In mice-spiked samples, one-way ANOVA results showed that the observed inhibition was not statistically significant between spiked samples and negative control (p-value = 0.164). Similarly, the observed differences in inhibition between venom-challenged and negative control samples were not statistically significant (p-value = 0.9109). At an LOD of 0.01 µg/mL, the assay was able to confirm the presence of 3FTxs in the samples. Our results show a proof of concept for the use of an inhibition ELISA model as a tool for detecting 3FTxs in the venoms of African spitting cobra snakes.  相似文献   
53.
54.
55.
56.
Recently Suslov and Tran (2008) [1] claimed to have found an error in one of the solutions given in the paper by Hron (2001) et al. [2] concerning the flows of fluids with pressure-dependent viscosities. We show that their arguments are related to the question of the continuity of the pressure, and we show that the original solution, although it is not a classical one, can be interpreted as a solution in a generalized sense. Mathematical and physical implications of such generalizations are briefly discussed. The discussion in the paper highlights the importance of recognizing what is meant by a “solution” to a partial differential equation, whether by a solution we mean a classical solution, a weak solution, or a solution in some other sense.  相似文献   
57.
The charge transport properties of thin films prepared from colloidal dispersion of polyaniline stabilized by poly(N‐vinylpyrrolidone) (PANI/PVP) have been investigated. The electrical characterization of coplanar device comprising of gold electrodes and PANI/PVP film deposited by spin coating served to gain insights into the contact and bulk resistance. The films prepared from PANI/PVP colloidal dispersion show high stability over a large temperature range. Temperature dependent measurements in the range from 90 to 350 K reveal that the charge transport can be described by a three‐dimensional variable‐range hopping mechanism as the dominant mode in the films. The stability of the films cast from dispersion within a large temperature range opens the possibility of the application as a polymer semiconductor layer in sensors and charge‐transport interlayer in organic solar cells. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1710–1716  相似文献   
58.
59.
Up to now molecular-orbital calculations of the electronic states of linear mixed crystals have been concerned only with binary systems such as AB, AB2, and A2B2. The purpose of the present treatment is to extend this work to crystals whose elementary cells contain any number of different atoms in any ordered sequence. The formulation of this general theory is based on the resolvent method. Although the approach enables the general properties of delocalized and localized states to be discussed, the more simple cases already solved in the literature can still be easily derived from the general equations. Furthermore, the classification of Tamm and Shockley states retains its significance, even when other kinds of states can occur and various transitions between the clear cut cases can exist. As in earlier investigations, the chemisorption states are related to surface states and have similar properties. The resolvent method is summarized in the Appendix and its connection with the partition technique is shown.  相似文献   
60.
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