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   1351721篇
  免费   30404篇
  国内免费   8408篇
化学   678030篇
晶体学   14932篇
力学   75200篇
综合类   162篇
数学   243497篇
物理学   378712篇
  2021年   13438篇
  2020年   16011篇
  2019年   16123篇
  2018年   13465篇
  2016年   28337篇
  2015年   21036篇
  2014年   30612篇
  2013年   74696篇
  2012年   39873篇
  2011年   38085篇
  2010年   38338篇
  2009年   40461篇
  2008年   36882篇
  2007年   33014篇
  2006年   38142篇
  2005年   31076篇
  2004年   31752篇
  2003年   29691篇
  2002年   30421篇
  2001年   29789篇
  2000年   25732篇
  1999年   22916篇
  1998年   21198篇
  1997年   21143篇
  1996年   19295篇
  1995年   18618篇
  1994年   18140篇
  1993年   17684篇
  1992年   17688篇
  1991年   17946篇
  1990年   17115篇
  1989年   17140篇
  1988年   16752篇
  1987年   16726篇
  1986年   15680篇
  1985年   22194篇
  1984年   23469篇
  1983年   19551篇
  1982年   21296篇
  1981年   20477篇
  1980年   19822篇
  1979年   20109篇
  1978年   21432篇
  1977年   21085篇
  1976年   20878篇
  1975年   19569篇
  1974年   19225篇
  1973年   19764篇
  1972年   14282篇
  1967年   12604篇
排序方式: 共有10000条查询结果,搜索用时 408 毫秒
141.
Crystallography Reports - The three-dimensional structure of recombinant thermophilic ribokinase from Thermus speсies 2.9 was determined at 2.4 Å resolution using crystals, which were...  相似文献   
142.
143.
Statistical Inference for Stochastic Processes - The problem of linear interpolation in the context of a multivariate time series having multiple (possibly non-consecutive) missing values is...  相似文献   
144.
Siberian Mathematical Journal - A lattice homomorphism between quasi-Banach lattices is known to be compact if and only if it is a sum of a series of rank one lattice...  相似文献   
145.
Theoretical and Mathematical Physics - This paper is devoted to tetrahedron maps, which are set-theoretical solutions of the Zamolodchikov tetrahedron equation. We construct a family of tetrahedron...  相似文献   
146.
CRANAD-2 is a fluorogenic curcumin derivative used for near-infrared detection and imaging in vivo of amyloid aggregates, which are involved in neurodegenerative diseases. We explore the performance of CRANAD-2 in two super-resolution imaging techniques, namely stimulated emission depletion (STED) and single-molecule localization microscopy (SMLM), with markedly different fluorophore requirements. By conveniently adapting the concentration of CRANAD-2, which transiently binds to amyloid fibrils, we show that it performs well in both techniques, achieving a resolution in the range of 45–55 nm. Correlation of SMLM with atomic force microscopy (AFM) validates the resolution of fine features in the reconstructed super-resolved image. The good performance and versatility of CRANAD-2 provides a powerful tool for near-infrared nanoscopic imaging of amyloids in vitro and in vivo.  相似文献   
147.
Designs, Codes and Cryptography - Given an integer $$k\ge 3$$ and a group G of odd order,  if there exists a 2-(v, k, 1)-design and if v is sufficiently large then there...  相似文献   
148.
Journal of Analytical Chemistry - Silver nanoparticles modified with Eu3+ ions increase the intensity of the fluorescence signal by a factor of 125 in an analytical system containing doxycycline as...  相似文献   
149.
Computational Optimization and Applications - We consider a continuous-time optimization method based on a dynamical system, where a massive particle starting at rest moves in the conservative...  相似文献   
150.
The health monitoring has been studied to ensure integrity of design of engine structure by detection, quantification, and prediction of damages. Early detection of faults may allow the downtime of maintenance to be rescheduled, thus preventing sudden shutdown of machines. In cylinder pressure developed, vibrations and noise emissions data provide a rich source of information about condition of engines. Monitoring of vibrations and noise emissions are novel non-intrusive methodologies for which positioning of various transducers are important issue. The presented work shows applicability of these diagnosis methodologies adopted in case of diesel engines. The effects of changing various fuel injection parameters was analyzed. Scope of using non-intrusive technique has been analyzed by changing locations of microphone. Novelty of this worklies in exploring signal processing methods for various locations around the engine test set up. Various frequency ranges of contributing noise and vibration sources were identified. Time-Frequency analysis showed the onset of various cyclic. Based on the identification of various frequency bands, it is possible to device suitable filters in order to extract more information.  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