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   195446篇
  免费   2210篇
  国内免费   613篇
化学   108467篇
晶体学   3304篇
力学   7832篇
综合类   4篇
数学   18371篇
物理学   60291篇
  2016年   2293篇
  2015年   1702篇
  2014年   2414篇
  2013年   7897篇
  2012年   5299篇
  2011年   6659篇
  2010年   4445篇
  2009年   4387篇
  2008年   6034篇
  2007年   6190篇
  2006年   5955篇
  2005年   5439篇
  2004年   4983篇
  2003年   4457篇
  2002年   4326篇
  2001年   5797篇
  2000年   4409篇
  1999年   3531篇
  1998年   2749篇
  1997年   2784篇
  1996年   2742篇
  1995年   2522篇
  1994年   2410篇
  1993年   2297篇
  1992年   2811篇
  1991年   2675篇
  1990年   2629篇
  1989年   2654篇
  1988年   2596篇
  1987年   2598篇
  1986年   2415篇
  1985年   3279篇
  1984年   3301篇
  1983年   2725篇
  1982年   2918篇
  1981年   2849篇
  1980年   2757篇
  1979年   2900篇
  1978年   3141篇
  1977年   2968篇
  1976年   2895篇
  1975年   2763篇
  1974年   2708篇
  1973年   2723篇
  1972年   1762篇
  1971年   1470篇
  1968年   1933篇
  1967年   2133篇
  1966年   1922篇
  1965年   1500篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
51. IntroductionL. H5.m.nd..l3] solved the 0problem by using the L2-estimates for partial differentialoperators in C'.. J. Kajiwara[4] studied infinite dimensional generalizations of the poten-tial kernel. Concerning the 0-problem in infinite dimensional spaces, P. ffeb.i.lll] investi-gated the a-equation for coc (o, 1)-forms in arbitrary pseudoconvex open subsets of separableHilbert spaces without growth condition. J. F. Colombeau and B. Perr.t[l1 showed that aCoc solution u of 0u = w ca…  相似文献   
132.
133.
Seven new monogalactosyl diacylglycerols (1-7) and six new digalactosyl diacylglycerols (11-16) were isolated from an axenically cultured cyanobacterium, P. tenue. Their structures were elucidated on the basis of physicochemical evidence and the results of enzymatic hydrolysis using a lipase (from Rhizopus arrhizus). Comparison of antialgal activity for P. tenue between monogalactosyl diacylglycerols (1-8) and digalactosyl diacylglycerols (11-19) revealed that the former showed more potent activity than the latter.  相似文献   
134.
The buffer extracts (3S) of sclerotia of Sclerotinia sclerotiorum IFO 9395 contained mitogenic substance(s) to murine splenocytes (Shinohara et al. Chem. Pharm. Bull., 38, 2219 (1990)). Although the native 3S was slightly mitogenic, heating of 3S induced significant mitogenic activity. To isolate the mitogen, we separated 3S by ion-exchange and gel filtration chromatographies. The isolated mitogen, named sclerogen, has a molecular mass of 32 kilodaltons (kDa) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and the isoelectric point (pI) of 5.9 by chromatofocusing. Sclerogen was significantly mitogenic in vitro against murine splenocytes after heat denaturation, and also showed the augmentation of the primary mixed lymphocyte reaction (MLR) in vitro. However, sclerogen did not show the activation of an alternative pathway of complement and hemagglutination activity. These results suggest that sclerogen is a unique mitogen which differs from lectins and shows mitogenicity after heat denaturation.  相似文献   
135.
The presence of copper atoms as continuous networks at the grain boundaries of an aluminium-copper alloy has been considered not preventing the moving of dislocations during creep (or at least partially). The dislocations can bs absorbed by these boundaries and penetrate through them. That leads to changés of shape and structure of grains and also to the sliding of grains against each other. This was deduced from the accelerating increase in the sensitivity of the steady state creep rate to the applied stress of an aluminium 2·8 wt% copper alloy examined at wide range of temperatures (50–350 °C) and applied stresses (7–170 MPa). This rapid increase in the sensitivity parameter of the steady state creep rate occurs in Al-Cu alloys at quite higher ranges of applied stresses and may be attributed mainly to the contribution of the grain boundary movements to the creep strain.  相似文献   
136.
137.
138.
139.
140.
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