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   420786篇
  免费   6610篇
  国内免费   2606篇
化学   224199篇
晶体学   5920篇
力学   17439篇
综合类   18篇
数学   55567篇
物理学   126859篇
  2021年   4343篇
  2020年   4677篇
  2019年   5123篇
  2018年   6787篇
  2017年   6929篇
  2016年   10323篇
  2015年   6588篇
  2014年   9587篇
  2013年   21695篇
  2012年   18086篇
  2011年   20990篇
  2010年   14562篇
  2009年   14285篇
  2008年   18354篇
  2007年   18137篇
  2006年   16762篇
  2005年   14999篇
  2004年   14017篇
  2003年   12071篇
  2002年   11753篇
  2001年   12008篇
  2000年   9229篇
  1999年   7200篇
  1998年   5988篇
  1997年   5738篇
  1996年   5691篇
  1995年   4746篇
  1994年   4707篇
  1993年   4565篇
  1992年   4938篇
  1991年   4973篇
  1990年   4782篇
  1989年   4605篇
  1988年   4412篇
  1987年   4469篇
  1986年   4217篇
  1985年   5450篇
  1984年   5488篇
  1983年   4484篇
  1982年   4624篇
  1981年   4366篇
  1980年   4245篇
  1979年   4482篇
  1978年   4439篇
  1977年   4402篇
  1976年   4372篇
  1975年   4133篇
  1974年   4094篇
  1973年   4144篇
  1972年   2842篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
51.
Siberian Mathematical Journal - We give a simple proof of one assertion used in solving Waring’s problem.  相似文献   
52.
53.
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   
54.
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   
55.
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   
56.
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   
57.
Crystallography Reports - Two LiInSe2 single crystals, grown under different conditions, have been studied. Characteristics of these crystals for neutron detection have been compared using...  相似文献   
58.
59.
Svetlakova  A. V.  Mendez  M. Sanchez  Tuchin  E. S.  Khodan  A. N.  Traore  M.  Azouani  R.  Kanaev  A.  Tuchin  V. V. 《Optics and Spectroscopy》2021,129(8):846-850
Optics and Spectroscopy - We study the photocatalytic activity of nanocomposites based on θ-phase alumina (Al2O3) with different TiO2 concentrations for heterogeneous photocatalysis and...  相似文献   
60.
Journal of Structural Chemistry - Structural parameters and relative Gibbs free energies are calculated by density functional theory methods for four tetrafluoro derivatives of zinc(II)...  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