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   99157篇
  免费   874篇
  国内免费   833篇
  100864篇
  2022年   54篇
  2021年   110篇
  2020年   54篇
  2019年   66篇
  2018年   11902篇
  2017年   10723篇
  2016年   7558篇
  2015年   747篇
  2014年   488篇
  2013年   552篇
  2012年   4512篇
  2011年   13106篇
  2010年   12220篇
  2009年   8375篇
  2008年   10076篇
  2007年   11633篇
  2006年   494篇
  2005年   731篇
  2004年   1183篇
  2003年   1242篇
  2002年   978篇
  2001年   395篇
  2000年   289篇
  1999年   151篇
  1998年   90篇
  1997年   89篇
  1996年   80篇
  1995年   62篇
  1994年   57篇
  1993年   89篇
  1992年   131篇
  1991年   157篇
  1990年   102篇
  1989年   114篇
  1988年   131篇
  1987年   106篇
  1986年   88篇
  1985年   78篇
  1984年   87篇
  1983年   81篇
  1982年   53篇
  1981年   53篇
  1980年   65篇
  1979年   73篇
  1978年   70篇
  1976年   61篇
  1975年   61篇
  1973年   61篇
  1972年   300篇
  1971年   308篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
A method nearly identical with that used by Rafalko on small amoebae, oocyte prophases of Habrobracon and several yeasts, has been found confirmatory to his results when applied to mammalian testicular tissue. The method is described, additional preparational notes are given, and several questions raised on possible improvement of the technic.  相似文献   
43.
44.
45.
46.
47.
48.
49.
Recent advances in virology, gene therapy, and molecular and cell biology have provided insight into the mechanisms through which viruses can boost the anti-tumor immune response, or can infect and directly kill tumor cells. A recent experimental report (Bridle et al. in Molec. Ther. 18(8):1430–1439, 2010) showed that a sequential treatment approach that involves two viruses that carry the same tumor antigen leads to an improved anti-tumor response compared to the effect of each virus alone. In this article, we derive a mathematical model to investigate the anti-tumor effect of two viruses, and their interactions with the immune cells. We discuss the conditions necessary for permanent tumor elimination and, in this context, we stress the importance of investigating the long-term effect of non-linear interactions. In particular, we discuss multi-stability and multi-instability, two complex phenomena that can cause abrupt transitions between different states in biological and physical systems. In the context of cancer immunotherapies, the transitions between a tumor-free and a tumor-present state have so far been associated with the multi-stability phenomenon. Here, we show that multi-instability can also cause the system to switch from one state to the other. In addition, we show that the multi-stability is driven by the immune response, while the multi-instability is driven by the presence of the virus.  相似文献   
50.
Chondroitin sulfate (CS) is the most abundant glycosaminoglycan (GAG) in the central nervous system (CNS) matrix. Its sulfation and epimerization patterns give rise to different forms of CS, which enables it to interact specifically and with a significant affinity with various signalling molecules in the matrix including growth factors, receptors and guidance molecules. These interactions control numerous biological and pathological processes, during development and in adulthood. In this review, we describe the specific interactions of different families of proteins involved in various physiological and cognitive mechanisms with CSs in CNS matrix. A better understanding of these interactions could promote a development of inhibitors to treat neurodegenerative diseases.  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