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   1450篇
  免费   43篇
  国内免费   11篇
化学   1102篇
晶体学   2篇
力学   13篇
数学   228篇
物理学   159篇
  2023年   8篇
  2022年   42篇
  2021年   55篇
  2020年   25篇
  2019年   25篇
  2018年   26篇
  2017年   23篇
  2016年   41篇
  2015年   35篇
  2014年   46篇
  2013年   89篇
  2012年   84篇
  2011年   92篇
  2010年   71篇
  2009年   53篇
  2008年   96篇
  2007年   84篇
  2006年   99篇
  2005年   76篇
  2004年   61篇
  2003年   53篇
  2002年   46篇
  2001年   23篇
  2000年   20篇
  1999年   11篇
  1998年   21篇
  1997年   9篇
  1996年   13篇
  1995年   11篇
  1994年   16篇
  1993年   10篇
  1992年   9篇
  1991年   9篇
  1990年   11篇
  1989年   11篇
  1988年   4篇
  1987年   10篇
  1985年   14篇
  1984年   12篇
  1983年   5篇
  1982年   7篇
  1981年   5篇
  1980年   6篇
  1978年   5篇
  1977年   4篇
  1976年   2篇
  1975年   5篇
  1973年   4篇
  1971年   4篇
  1943年   2篇
排序方式: 共有1504条查询结果,搜索用时 218 毫秒
51.
52.
This is a survey paper on recent results indicated in the title. In contrast to the famous examples of Kolmogorov and Fejér on the pointwise divergence of Fourier series, the statistical convergence of the Fourier series of any integrable function takes place at almost every point; and the statistical convergencr of the Fourier series of any continuous function is uniform. Furthermore, Tauberian conditions are also presented, under which ordinary convergence of any sequence of real or complex numbers follows from its statistical summability.  相似文献   
53.
Ammonolysis (25% aqueous NH3 - alcohols or THF) of carboxylic esters obtained from diastereoisomerically pure α-hydroxyphosphonates leads to recovery of the phosphonates without racemization in good to excellent yields.  相似文献   
54.
General Lp dual curvature measures have recently been introduced by Lutwak, Yang and Zhang [24]. These new measures unify several other geometric measures of the Brunn–Minkowski theory and the dual Brunn–Minkowski theory. Lp dual curvature measures arise from qth dual intrinsic volumes by means of Alexandrov-type variational formulas. Lutwak, Yang and Zhang [24] formulated the Lp dual Minkowski problem, which concerns the characterization of Lp dual curvature measures. In this paper, we solve the existence part of the Lp dual Minkowski problem for p>1 and q>0, and we also discuss the regularity of the solution.  相似文献   
55.
56.
57.
58.
59.
Thermoporosimetry, i.e., DSC measurements of melting point depression of water and heptane confined in mesopores, has been used for determination the pore size distribution of several mesoporous silicas synthesized with the use of micelle templates. Porosity of these materials was additionally characterized by low-temperature nitrogen adsorption and quasi-equilibrated thermodesorption of nonane. The pore size distributions obtained using the water thermoporosimetry were similar to those determined using the other methods, but the pore size values found for the narrow pore materials were underestimated by ca 1?nm. Too large pore sizes obtained for the wide pore silica from heptane thermoporosimetry were attributed to nonlinear dependence of the melting point depression on the reciprocal of the pore size.  相似文献   
60.
The binding of vitamin B12 derivatives to human B12 transporter proteins is strongly influenced by the type and site of modification of the cobalamin original structure. We have prepared the first cobalamin derivative modified at the phosphate moiety. The reaction conditions were fully optimized and its limitations examined. The resulting derivatives, particularly those bearing terminal alkyne and azide groups, were isolated and used in copper‐catalyzed alkyne–azide cycloaddition reactions (CuAAC). Their sensitivity towards light revealed their potential as photocleavable molecules. The binding abilities of selected derivatives were examined and compared with cyanocobalamin. The interaction of the alkylated derivatives with haptocorrin was less affected than the interaction with intrinsic factor. Furthermore, the configuration of the phosphate moiety was irrelevant to the binding process.  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