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   249159篇
  免费   1674篇
  国内免费   266篇
电工技术   4043篇
综合类   91篇
化学工业   40355篇
金属工艺   15145篇
机械仪表   10068篇
建筑科学   4187篇
矿业工程   3760篇
能源动力   3875篇
轻工业   9722篇
水利工程   4095篇
石油天然气   13006篇
武器工业   28篇
无线电   20193篇
一般工业技术   62777篇
冶金工业   32186篇
原子能技术   11135篇
自动化技术   16433篇
  2021年   2760篇
  2019年   2735篇
  2018年   5432篇
  2017年   5715篇
  2016年   6049篇
  2015年   3055篇
  2014年   5326篇
  2013年   10089篇
  2012年   7310篇
  2011年   8942篇
  2010年   7298篇
  2009年   8111篇
  2008年   8176篇
  2007年   7859篇
  2006年   6367篇
  2005年   5564篇
  2004年   5481篇
  2003年   5300篇
  2002年   5134篇
  2001年   4949篇
  2000年   4941篇
  1999年   4256篇
  1998年   7191篇
  1997年   5846篇
  1996年   4425篇
  1995年   3660篇
  1994年   3431篇
  1993年   3628篇
  1992年   3217篇
  1991年   3359篇
  1990年   3482篇
  1989年   3369篇
  1988年   3268篇
  1987年   3261篇
  1986年   3157篇
  1985年   3317篇
  1984年   3252篇
  1983年   3149篇
  1982年   2994篇
  1981年   3045篇
  1980年   3071篇
  1979年   3257篇
  1978年   3490篇
  1977年   3461篇
  1976年   3914篇
  1975年   3209篇
  1974年   3293篇
  1973年   3342篇
  1972年   2987篇
  1971年   2754篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
151.
All-Union Scientific-Research Institute of Nuclear Physics at the S. M. Kirov Tomsk Polytechnical University. Translated from Atomnaya énergiya, Vol. 79, No. 1, pp. 38–40, July, 1995.  相似文献   
152.
NIKIÉT. Translated from Atomnaya Énergiya, Vol. 75, No. 4, pp. 265-269, October, 1993.  相似文献   
153.
A mathematical model of dissolution of gas in a metal is suggested with account of phase formation in accordance with the phase constitution diagram (PCD). The stage-by-stage saturation process to the final product formation is shown for an individual particle, through which a reaction wave passes, depending on the diffusion permeability of the metal and solubility conditions that obey Sieverts's law. The effect of the filtration supply of the oxidant to the reaction zone and the process exothermicity on the course of the process is shown.Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 4, pp. 447–450, October, 1993.  相似文献   
154.
Large deflections of pulse-loaded elliptic and round plates made of hardenable elastoplastic materials are investigated analytically using an energy-based approach. Formulas that are convenient for engineering design have been derived.  相似文献   
155.
156.
The adoption of unified fracture mechanics terminology (UFMT) will promote efficient communication between specialists in different fields of fracture research, harmonization of national and international standards relating to fracture mechanics, and last but not least improvement of the existing methodology for teaching and education in fatigue and fracture. In this paper the definitions of some basic and related terms included in different standards on fracture mechanics terminology are confronted with one another. Alternative definitions of the same terms are offered. By this strategy the author tries to show that the definitions of basic and related terms appropriate for the UFMT should emerge as a consequence of harmonizing a crack model with an actual crack and then both taken together with a fracture model, laboratory test methods, and failure assessment codes.Published in Problemy Prochonsti, No. 1, pp. 17–29, January, 1996.This paper is published as a matter of discussion.  相似文献   
157.
158.
159.
Buffalo milk Cheddar cheese samples of different ages were analysed for compositional attributes (CA), ripening indices (RI) and Instron Textural Profile (ITP). All samples were compositionally alike, except for pH and salt-in-moisture (SM) contents. RI showed significant variations. CA and RI showed highly significant correlations within themselves and with each other, except for moisture with pH, SM with moisture, MNFS, Fat and FDM and Fat with MNFS. The ITPs of cheeses showed significant variations and had highly significant intercorrelations indicating their interdependence. CA (except moisture and MNFS) and RI showed a highly significant correlationship with ITPs. Moisture content showed a highly significant correlationship with all ITPs, except cohesiveness and springiness, where it was significant. MNFS content showed significant correlations only with hardness and brittleness. Stepwise regression analysis revealed that MI was the most predominant factor influencing cheese texture, followed by pH, SM, FDM and TVFA. Knowing Ca and RI, the textural properties of cheeses can be forecast through mathematical equations. Similarly the age of cheese can also be predicted if RI and/or textural properties are known.  相似文献   
160.
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