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   180389篇
  免费   871篇
  国内免费   164篇
化学   76369篇
晶体学   2540篇
力学   10577篇
综合类   1篇
数学   33160篇
物理学   58777篇
  2021年   1009篇
  2020年   1061篇
  2019年   1281篇
  2018年   10444篇
  2017年   11274篇
  2016年   6398篇
  2015年   1997篇
  2014年   2074篇
  2013年   3846篇
  2012年   7516篇
  2011年   16177篇
  2010年   9924篇
  2009年   10067篇
  2008年   13928篇
  2007年   17486篇
  2006年   3160篇
  2005年   9317篇
  2004年   5827篇
  2003年   5741篇
  2002年   3767篇
  2001年   2470篇
  2000年   2057篇
  1999年   1352篇
  1998年   1212篇
  1997年   1099篇
  1996年   1113篇
  1995年   974篇
  1994年   940篇
  1993年   934篇
  1992年   968篇
  1991年   1022篇
  1990年   953篇
  1989年   995篇
  1988年   915篇
  1987年   872篇
  1986年   819篇
  1985年   974篇
  1984年   1081篇
  1983年   921篇
  1982年   935篇
  1981年   855篇
  1980年   796篇
  1979年   882篇
  1978年   1012篇
  1977年   945篇
  1976年   881篇
  1975年   831篇
  1974年   838篇
  1973年   855篇
  1972年   593篇
排序方式: 共有10000条查询结果,搜索用时 921 毫秒
1.
Journal of Experimental and Theoretical Physics - Dzyaloshinskii–Moriya interaction, DMI in short, represents an antisymmetric type of magnetic interactions that favor orthogonal orientation...  相似文献   
2.
Crystallography Reports - The crystal structure and crystallochemical features of a Fe-deficient zirconium-rich analog of eudialyte from the Lovozero alkaline massif (Kola peninsula) have been...  相似文献   
3.
Russian Journal of General Chemistry - Aminophosphabetaines, i.e., isobutyl {[alkyl(dimethyl)ammonio]methyl}phosphonates with higher alkyl substituents at the nitrogen atom, were obtained by a...  相似文献   
4.
Kinetics and Catalysis - The results of studies in the field of synthesis and characterization of layered double hydroxides (LDHs) obtained using solid-phase reactions are summarized. The effect of...  相似文献   
5.
Mechanics of Composite Materials - Carbon fiber (CF)/ polyamide (PA6) composites are one of the most promising thermoplastic materials for automobile applications. However, the interfacial...  相似文献   
6.
Russian Journal of Applied Chemistry - A method for the disposal of hydrolysis lignin waste based on its modification with ZnCl2 and FeCl3 and subsequent carbonization at 800°C was proposed....  相似文献   
7.
Mathematical Notes - Subspaces of the space of analytic functions on a convex domain in the complex plane that are invariant with respect to the differentiation operator are studied. The problem of...  相似文献   
8.
Russian Physics Journal - The specific features of the sorption activity of silver nanoparticles (AgNPs) on biodegradable polymers of natural (collagen) and artificial (polyamide 6.6) origin have...  相似文献   
9.
General Relativity and Gravitation - In previous work, we established theoretical results concerning the effect of matter shells surrounding a gravitational wave (GW) source, and we now apply these...  相似文献   
10.
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