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   17260篇
  免费   1217篇
  国内免费   97篇
  2024年   23篇
  2023年   159篇
  2022年   415篇
  2021年   738篇
  2020年   462篇
  2019年   603篇
  2018年   652篇
  2017年   528篇
  2016年   724篇
  2015年   959篇
  2014年   1047篇
  2013年   1335篇
  2012年   1465篇
  2011年   1288篇
  2010年   849篇
  2009年   707篇
  2008年   859篇
  2007年   807篇
  2006年   717篇
  2005年   670篇
  2004年   598篇
  2003年   475篇
  2002年   450篇
  2001年   181篇
  2000年   145篇
  1999年   132篇
  1998年   108篇
  1997年   78篇
  1996年   74篇
  1995年   78篇
  1994年   59篇
  1993年   69篇
  1992年   78篇
  1991年   72篇
  1990年   84篇
  1989年   75篇
  1988年   64篇
  1987年   54篇
  1986年   52篇
  1985年   65篇
  1984年   64篇
  1983年   48篇
  1982年   47篇
  1981年   43篇
  1980年   30篇
  1979年   33篇
  1978年   32篇
  1977年   25篇
  1976年   33篇
  1975年   29篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
2.
3.
4.
5.
6.
Perspective texture synthesis has great significance in many fields like video editing, scene capturing etc., due to its ability to read and control global feature information. In this paper, we present a novel example-based, specifically energy optimization-based algorithm, to synthesize perspective textures. Energy optimization technique is a pixel-based approach, so it’s time-consuming. We improve it from two aspects with the purpose of achieving faster synthesis and high quality. Firstly, we change this pixel-based technique by replacing the pixel computation with a little patch. Secondly, we present a novel technique to accelerate searching nearest neighborhoods in energy optimization. Using k- means clustering technique to build a search tree to accelerate the search. Hence, we make use of principal component analysis (PCA) technique to reduce dimensions of input vectors. The high quality results prove that our approach is feasible. Besides, our proposed algorithm needs shorter time relative to other similar methods.  相似文献   
7.
One novel approach for the biological delivery of peptide drugs is to incorporate the sequence of the peptide into the structure of a natural transport protein such as human serum transferrin (HST). However, a potential drawback is that the HST may increase the immunoreactivity of the peptide, in the same way that carrier proteins can be used to generate highly immunogenic peptide hapten conjugates. In this study we have generated a recombinant HST carrier protein that contains a peptide substrate of HIV-1 protease (VSQNYPIVL). The protein retained native HST function, and the peptide was surface exposed since it was immunoreactive in native dot blots, and was cleaved by HIV-1 protease. Immunisation of rabbits with the recombinant protein elicited only a very poor anti-peptide immune response. In contrast, strong anti-peptide immune responses were raised against both the peptide alone, and a chemical conjugate of the peptide with HST. These data demonstrate that it is possible to attenuate the immune response normally directed against an immunogenic peptide sequence by engineering into a surface exposed loop of HST. These findings may have an important impact on the future design of peptide delivery systems.  相似文献   
8.
The phosphoproteins of Dictyostelium discoideum were compared at different stages of development by polyacrylamide gel electrophoresis. Certain phosphoproteins of vegetative amoebae were conserved while others appeared and disappeared during development. Four major phosphoproteins with apparent subunit molecular weights of 50,000, 47,000, 38,000, and 34,000 disappeared precociously in response to exogenous cAMP. Two membranal phosphoproteins, with apparent subunit molecular weights of 80,000 and 81,000, appeared precociously in response to added cAMP. One of these phosphoproteins, molecular weight of 80,000, has been identified tentatively as the “contact site A” glycoprotein. Another membranal protein, with apparent subunit molecular weight of 42,000, unaffected in its appearance by cAMP, has been identified tentatively as phosphoactin.  相似文献   
9.
10.
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