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   110299篇
  免费   8741篇
  国内免费   8819篇
  2024年   139篇
  2023年   1268篇
  2022年   1902篇
  2021年   5510篇
  2020年   3811篇
  2019年   4746篇
  2018年   4484篇
  2017年   3301篇
  2016年   4685篇
  2015年   6841篇
  2014年   8056篇
  2013年   8549篇
  2012年   10294篇
  2011年   9322篇
  2010年   5773篇
  2009年   5155篇
  2008年   5903篇
  2007年   5334篇
  2006年   4601篇
  2005年   3665篇
  2004年   3136篇
  2003年   2846篇
  2002年   2417篇
  2001年   1922篇
  2000年   1744篇
  1999年   1722篇
  1998年   1072篇
  1997年   1025篇
  1996年   966篇
  1995年   854篇
  1994年   811篇
  1993年   635篇
  1992年   857篇
  1991年   655篇
  1990年   498篇
  1989年   475篇
  1988年   383篇
  1987年   367篇
  1986年   290篇
  1985年   312篇
  1984年   183篇
  1983年   184篇
  1982年   118篇
  1981年   101篇
  1980年   74篇
  1979年   97篇
  1978年   72篇
  1977年   71篇
  1975年   71篇
  1974年   70篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
71.
Bone and tooth, fundamental parts of the craniofacial skeleton, are anatomically and developmentally interconnected structures. Notably, pathological processes in these tissues underwent together and progressed in multilevels. Extracellular vesicles (EVs) are cell-released small organelles and transfer proteins and genetic information into cells and tissues. Although EVs have been identified in bone and tooth, particularly EVs have been identified in the bone formation and resorption, the concrete roles of EVs in bone and tooth development and diseases remain elusive. As such, we review the recent progress of EVs in bone and tooth to highlight the novel findings of EVs in cellular communication, tissue homeostasis, and interventions. This will enhance our comprehension on the skeletal biology and shed new light on the modulation of skeletal disorders and the potential of genetic treatment.  相似文献   
72.
We propose a methodology for digitally fusing diagnostic decisions made by multiple medical experts in order to improve accuracy of diagnosis. Toward this goal, we report an experimental study involving nine experts, where each one was given more than 8,000 digital microscopic images of individual human red blood cells and asked to identify malaria infected cells. The results of this experiment reveal that even highly trained medical experts are not always self-consistent in their diagnostic decisions and that there exists a fair level of disagreement among experts, even for binary decisions (i.e., infected vs. uninfected). To tackle this general medical diagnosis problem, we propose a probabilistic algorithm to fuse the decisions made by trained medical experts to robustly achieve higher levels of accuracy when compared to individual experts making such decisions. By modelling the decisions of experts as a three component mixture model and solving for the underlying parameters using the Expectation Maximisation algorithm, we demonstrate the efficacy of our approach which significantly improves the overall diagnostic accuracy of malaria infected cells. Additionally, we present a mathematical framework for performing ‘slide-level’ diagnosis by using individual ‘cell-level’ diagnosis data, shedding more light on the statistical rules that should govern the routine practice in examination of e.g., thin blood smear samples. This framework could be generalized for various other tele-pathology needs, and can be used by trained experts within an efficient tele-medicine platform.  相似文献   
73.
74.
75.
76.
A Melanesian variant of the genetic disease α-thalassemia has recently been shown to be due to a single-nucleotide polymorphism located between the adult α-globin genes and their enhancers. The finding that this mutation creates a novel promoter provides support for a mechanism of gene regulation by facilitated chromatin looping.  相似文献   
77.
78.
79.
80.
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