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   6675篇
  免费   170篇
  国内免费   37篇
化学   4946篇
晶体学   63篇
力学   119篇
数学   350篇
物理学   1404篇
  2023年   29篇
  2022年   40篇
  2021年   71篇
  2020年   69篇
  2019年   94篇
  2018年   62篇
  2017年   57篇
  2016年   127篇
  2015年   134篇
  2014年   148篇
  2013年   307篇
  2012年   363篇
  2011年   439篇
  2010年   240篇
  2009年   216篇
  2008年   383篇
  2007年   362篇
  2006年   342篇
  2005年   336篇
  2004年   346篇
  2003年   291篇
  2002年   310篇
  2001年   162篇
  2000年   152篇
  1999年   102篇
  1998年   84篇
  1997年   77篇
  1996年   85篇
  1995年   74篇
  1994年   81篇
  1993年   82篇
  1992年   84篇
  1991年   60篇
  1990年   58篇
  1989年   68篇
  1988年   56篇
  1987年   53篇
  1986年   62篇
  1985年   106篇
  1984年   100篇
  1983年   34篇
  1982年   49篇
  1981年   43篇
  1980年   45篇
  1979年   71篇
  1978年   51篇
  1977年   54篇
  1976年   47篇
  1975年   37篇
  1974年   27篇
排序方式: 共有6882条查询结果,搜索用时 0 毫秒
31.
32.
Dichlorophene was used as a model drug. Drug-carrying latex particles were prepared by soap-free emulsion copolymerization of dichlorophene acrylate with some hydrophilic methacrylate comonomers. The comonomers used affected not only the structure and colloidal stability of particles, but also the drug-activity of particles. Preliminary study of the drug activity revealed that highly hydrophilic latex particles were very stable and too inactive to be engulfed by amoebae and kill them. On the contrary, less hydrophilic particles carrying a large amount of drug can be an effective device to release drugs at a moderate rate to fight against extracelluar targets such as parasites.  相似文献   
33.
An evaluation of LH- and FSH-RIA BEAD kits based on IRMA was carried out. The results obtained with the methods characterized by the use of monoclonal antibodies, i.e., one is linked to solid phase, and another is isotopically labeled, were compared with those determined by the Daiichi LH- and FSH-kits. Intra- and inter-assay precision, recovery, linearity, and specificity of both methods were favorable without exceptions. The cross reactivity of the LH kit to 5,000 mIU/ml hCG revealed within the range of less than 3 mIU/ml. Significant correlations were observed between the results derived from conventional Daiichi LH- and FSH-kits. The results from the conventional kits exhibited 30 to 40% of those from the Daiichi kits, considered to be mainly due to the difference in standard calibrations used. Among the individuals within the normal menstrual cycle, the serum LH- and FSH-levels determined by the present kits gave a typical pattern with a peak in the preovulatory phase. On the other hand, the LH- and FSH-values of individuals in normal pregnancy revealed strikingly decreased in comparison with those of non-pregnant women.  相似文献   
34.
The calixarene-fullerene interaction,which causes only a slight change in the absorptionspectra, has been substantiated by calorimetricmeasurements: the H° values arecomparable with those obtained from the associationconstants estimated by a spectroscopic method. Furthermore, we determined the association constantbetween homooxacalix[3]arene and [60]fullerenederivatives with a porphyrin moiety by fluorescencespectra.  相似文献   
35.
36.
37.
Thiazolo[3,2-a]thieno[3,2-d]-, [3,4-d]- and [2,3-d]pyrimidin-5-one derivatives (6, 11 and 16), and polymethylene condensed thieno[3,2-d]-, [3,4-d]- and [2,3-d]pyrimidin-5-one derivatives (19-21), in which the oxygen atom of the oxazolidine moiety in 3 was replaced by a sulfur atom or methylene groups, were synthesized and evaluated for gastric antisecretory activity in pylorus-ligated rats. The structure-activity relationships of these compounds are discussed.  相似文献   
38.
39.
40.
Quantitative determination of ppb-order 10B was carried out in a small number of cultured tumor cells by particle tracks by the 10B(n,)7Li reactions using solid state nuclear track detector (SSNTD) for boron neutron capture therapy research. The detection limit of 10B concentration in tumor cells is less than 1·10-3 ppm under our experimental conditions which permits the quantitative determination of 10B in a small number of boronated tumor cells (105/ml = ca. 0.1 mg). Boron quantities in tumor cells determined were well compatible with the tumor cell killing effects of boron neutron capture therapy.  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