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   8709篇
  免费   688篇
  国内免费   525篇
  2023年   81篇
  2022年   114篇
  2021年   320篇
  2020年   247篇
  2019年   276篇
  2018年   312篇
  2017年   233篇
  2016年   349篇
  2015年   414篇
  2014年   514篇
  2013年   569篇
  2012年   794篇
  2011年   749篇
  2010年   436篇
  2009年   392篇
  2008年   525篇
  2007年   474篇
  2006年   381篇
  2005年   372篇
  2004年   292篇
  2003年   240篇
  2002年   206篇
  2001年   163篇
  2000年   163篇
  1999年   96篇
  1998年   46篇
  1997年   31篇
  1996年   40篇
  1995年   35篇
  1994年   30篇
  1993年   22篇
  1992年   76篇
  1991年   78篇
  1990年   77篇
  1989年   62篇
  1988年   65篇
  1987年   58篇
  1986年   60篇
  1985年   53篇
  1984年   36篇
  1983年   41篇
  1982年   27篇
  1981年   23篇
  1980年   26篇
  1979年   40篇
  1978年   29篇
  1975年   26篇
  1974年   24篇
  1973年   23篇
  1968年   21篇
排序方式: 共有9922条查询结果,搜索用时 62 毫秒
1.
Indomethacin and substance BW-755C in experiments on isolated myometrium striae of pregnant white rats exert an inhibiting effect on the contractile uterus function due to inhibition of cyclooxygenase or lipoxygenase ways of the arachidonic acid transformation. Prostaglandin F2 alpha is sensitive to functioning of the cyclooxygenase and lipoxygenase ways of the arachidonic acid transformation, while oxytocin--only lipoxygenase one. Conclusions rest on results from multiparametric analysis of the contractile uterus function suggested by authors and confirmed by the pattern recognition method--the Karunen-Loev orthogonal decomposition.  相似文献   
2.
  1. Animal behavior is elicited, in part, in response to external conditions, but understanding how animals perceive the environment and make the decisions that bring about these behavioral responses is challenging.
  2. Animal heads often move during specific behaviors and, additionally, typically have sensory systems (notably vision, smell, and hearing) sampling in defined arcs (normally to the front of their heads). As such, head‐mounted electronic sensors consisting of accelerometers and magnetometers, which can be used to determine the movement and directionality of animal heads (where head “movement” is defined here as changes in heading [azimuth] and/or pitch [elevation angle]), can potentially provide information both on behaviors in general and also clarify which parts of the environment the animals might be prioritizing (“environmental framing”).
  3. We propose a new approach to visualize the data of such head‐mounted tags that combines the instantaneous outputs of head heading and pitch in a single intuitive spherical plot. This sphere has magnetic heading denoted by “longitude” position and head pitch by “latitude” on this “orientation sphere” (O‐sphere).
  4. We construct the O‐sphere for the head rotations of a number of vertebrates with contrasting body shape and ecology (oryx, sheep, tortoises, and turtles), illustrating various behaviors, including foraging, walking, and environmental scanning. We also propose correcting head orientations for body orientations to highlight specific heading‐independent head rotation, and propose the derivation of O‐sphere‐metrics, such as angular speed across the sphere. This should help identify the functions of various head behaviors.
  5. Visualizations of the O‐sphere provide an intuitive representation of animal behavior manifest via head orientation and rotation. This has ramifications for quantifying and understanding behaviors ranging from navigation through vigilance to feeding and, when used in tandem with body movement, should provide an important link between perception of the environment and response to it in free‐ranging animals.
  相似文献   
3.
4.
RegB is involved in the control of the phage T4 life cycle. It inactivates the phage early mRNAs when their translation is no more required. We determined its structure and identified residues involved in substrate binding. For this, all backbone and 90% of side-chain resonance frequencies were assigned.  相似文献   
5.
6.
7.
8.
9.
10.
All six available lysine residues in bacteriorhodopsin were amidinated with dimethyl-3,3'-dithiobispropionimidate, which is a crosslinking agent. The photocycle was studied by measuring light absorption and electric signals. The data show an essential change in the photocycle: instead of single components, the rise of the signal due to the M intermediate can be decomposed into two components, and the decay into three. The life-times and the intensities of these components and in general the proton pumping activity of bacteriorhodopsin depend only negligibly upon pH. Changes upon removing the crosslinks are not significantly different from those in the crosslinked samples. The lysine residues therefore may not be considered of primary importance in proton translocation.  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