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   8928篇
  免费   1277篇
  国内免费   934篇
化学   4723篇
晶体学   72篇
力学   417篇
综合类   41篇
数学   644篇
物理学   3049篇
无线电   2193篇
  2024年   37篇
  2023年   214篇
  2022年   224篇
  2021年   271篇
  2020年   322篇
  2019年   270篇
  2018年   235篇
  2017年   239篇
  2016年   368篇
  2015年   380篇
  2014年   441篇
  2013年   598篇
  2012年   655篇
  2011年   690篇
  2010年   490篇
  2009年   520篇
  2008年   525篇
  2007年   471篇
  2006年   456篇
  2005年   447篇
  2004年   343篇
  2003年   272篇
  2002年   284篇
  2001年   208篇
  2000年   234篇
  1999年   229篇
  1998年   193篇
  1997年   167篇
  1996年   200篇
  1995年   159篇
  1994年   157篇
  1993年   138篇
  1992年   136篇
  1991年   106篇
  1990年   73篇
  1989年   82篇
  1988年   57篇
  1987年   48篇
  1986年   42篇
  1985年   39篇
  1984年   21篇
  1983年   19篇
  1982年   15篇
  1981年   13篇
  1980年   9篇
  1979年   7篇
  1976年   4篇
  1973年   3篇
  1970年   6篇
  1957年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Drawing inspiration from the jumping motions of living creatures in nature, jumping robots have emerged as a promising research field over the past few decades due to great application potential in interstellar exploration, military reconnaissance, and life rescue missions. Early reviews mainly focused on jumping robots made of lightweight and rigid materials with mechanical components, concentrating on jumping control and stability. Herein, attention is paid to the jumping mechanisms of soft actuators assembled from various soft smarting materials and powered by different stimulus sources. The challenges and prospects of soft jumping actuators are also discussed. It is hoped that this review will contribute to the further development of soft jumping actuators and broaden their practical applications.  相似文献   
22.
23.
We investigate classical electronic collisions with a He(+) ion. Scattering functions, such as the scattering angle, collisional time, or energy of the outgoing electron, all exhibit an interesting hierarchial self-similar structure, which can be interpreted in terms of the indefinite number of electronic returns to the vicinity of the nucleus, encounters between electrons, and Keplerian excursions of electrons during the collisional processes. Based on this mechanism a binary coding is introduced to organize the dynamics of this three-body system and to provide an understanding of the self-similarity among generations of scale magnification, which yields escape rates that vary with the sectional cut into the parameter space. The self-similarity displayed within a single generation, on the other hand, can be simply tied to the periods of the two independent electronic excursions. The physical interpretation and the symbolic dynamics introduced here are generally useful for three-body collisional systems, including atomic, molecular, or stellar collisions.  相似文献   
24.
25.
A new self-assembled and highly oriented one-dimensional single-crystal nanostructure of WO3 with hexagonal form was successfully prepared by a mild, solution-based colloidal approach.  相似文献   
26.
The dissociation kinetics of metal ions from native metallothionein (Cd5Zn2-MT) of rat liver has been studied in the presence of external ligands including amino acids, peptide and polyamino polycarboxylic acids at 25°C. The study shows that the solution pH affects the metal dissociation process. Different ligands present different multiphasic kinetics. The possible mechanism of metal dissociation from metallothionein has been proposed.  相似文献   
27.
The structures of B32 and B32H2–32 with Ih symmetry have been investigated by means of ab initio calculations at STO-3G level. The relationship between molecular orbitals of them has been analyzed and their bonding properties have been discussed. Then the possibility of their existence, as well as the similarity and difference between B32 (B32H2–32) and C60 (C60H60) have been inferred.  相似文献   
28.
29.
30.
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