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   3334篇
  免费   74篇
  国内免费   2篇
电工技术   54篇
综合类   10篇
化学工业   669篇
金属工艺   118篇
机械仪表   56篇
建筑科学   144篇
矿业工程   9篇
能源动力   48篇
轻工业   296篇
水利工程   12篇
无线电   286篇
一般工业技术   487篇
冶金工业   689篇
原子能技术   20篇
自动化技术   512篇
  2023年   26篇
  2022年   37篇
  2021年   46篇
  2020年   39篇
  2019年   42篇
  2018年   45篇
  2017年   33篇
  2016年   47篇
  2015年   59篇
  2014年   75篇
  2013年   119篇
  2012年   123篇
  2011年   154篇
  2010年   120篇
  2009年   107篇
  2008年   135篇
  2007年   117篇
  2006年   147篇
  2005年   110篇
  2004年   81篇
  2003年   81篇
  2002年   94篇
  2001年   73篇
  2000年   56篇
  1999年   62篇
  1998年   147篇
  1997年   106篇
  1996年   89篇
  1995年   71篇
  1994年   66篇
  1993年   60篇
  1992年   51篇
  1991年   29篇
  1990年   44篇
  1989年   42篇
  1988年   31篇
  1987年   30篇
  1986年   28篇
  1985年   39篇
  1984年   30篇
  1983年   28篇
  1982年   31篇
  1981年   28篇
  1980年   26篇
  1979年   29篇
  1978年   27篇
  1977年   29篇
  1976年   46篇
  1975年   22篇
  1974年   21篇
排序方式: 共有3410条查询结果,搜索用时 15 毫秒
21.
22.
Dyeing leather is very different from dyeing textiles, not least because of the defects that are frequently present on the skins. Axel Landmann looks at the many defects that can occur, and how they affect the dyeing process.  相似文献   
23.
We extend a dynamic approach of behavior generation to the representation of spatial information. Two levels of dynamics integrate dead-reckoning, dominant far from home bases, and piloting, dominant near home bases. When the view-based piloting system recognizes a home base, visual place information recalibrates the dead-reckoning system, inverting the hierarchical ordering of the two dynamic levels by time scale inversion. Reference views taken at discrete home bases are recognized invariantly under rotation of views. This process yields compass information. Continuous translational information is obtained as a neural place representation built from view correlations with a scattered set of local views. This self-calibrating cognitive map couples into a dynamics of heading direction integrating the behaviors of obstacle avoidance and target acquisition. Targets can be designated in terms of the cognitive map. We demonstrate the dynamical model in simulation.  相似文献   
24.
A clean benchmark experiment on beryllium was performed with D-T neutrons at the FNS facility of the Japan Atomic Energy Agency. The main objective was to verify the integral data related to the tritium production on lithium isotopes. Tritium production rates, as well as activation reaction rates were measured inside the beryllium assembly that was shaped as a pseudo-cylindrical slab with an area-equivalent diameter of 628 mm and a thickness of 355 mm. Experimental results were analyzed with a three-dimensional Monte Carlo transport code MCNP-4C and FENDL/MC-2.0, JENDL-3.2/3.3 neutron transport libraries. Evaluation of reaction rates was based on the cross section data taken from the JENDL Dosimetry File and ENDF B-VI data libraries. Analysis shows that all calculation combinations (transport and activation cross section libraries) used for evaluation of reaction rates give data that is agreeable with measured values within 10%.  相似文献   
25.
26.
27.
Es werden die experimentellen und numerischen Ergebnisse dargelegt, um die gesamte Spannungs-Dehnungs-Kurve des Zugversuches mit sechs Kennwerten zu beschreiben. Dies sind: Elastizitätsmodul, Streckgrenze, Fließdehnung, Zugfestigkeit, Gleichmaßdehnung und Verfestigungsmodul. Dadurch werden auch im überelastischen Bereich numerische Beziehungen möglich zwischen: Verformungen und Spannungen, Dehngrenzen, Tangenten-Modulen und Arbeitsvermögen. Die Beziehungen erweitern die Ermittlung von Last- und Eigenspannungen, und die Berechnungen beim plastischen Umformen, beim Traglastverfahren und beim Messen von Kerbspannungen.  相似文献   
28.
Only two tumor suppressor gene loci, one on 3p25 and the MEN1 gene on 11q13, have thus far been implicated in the pathogenesis of sporadic human pancreatic endocrine tumors (PETs). A genome-wide allelotyping study of 28 human PETs was undertaken to identify other potential tumor suppressor gene loci. In addition to those on chromosomes 3p and 11q, frequent allelic deletions were identified on 3q (32%), 11p (36%), 16p (36%), and 22q (29%). Finer deletion mapping studies localized the smallest regions of common deletion to 3q27, 11p13, and 16p12.3-13.11. Potential candidate genes at these loci include WT1 (11p13), TSC2 (16p13), and NF2 (22q12), but no known tumor suppressor gene localizes to 3q27. The mean fractional allelic loss among these human PETs is 0.126, and no correlation was observed between allelic loss and clinical parameters, including age, sex, hormonal subtype, and disease stage. These findings highlight novel locations of tumor suppressor gene loci that contribute to the pathogenesis of human PETs, and several of these on 3p, 3q, and 22q are syntenic with loci on mouse chromosomes 9 and 16 that are implicated in a murine transgenic model of PETs.  相似文献   
29.
30.
The authors respond to the "relational" issue of Psychoanalytic Psychology (PP; Vol. 12, No. 1) and support Karol Marshall's remonstration about the need to clarify what exactly the category relational refers to. It is noteworthy that in this issue of PP the relational thinkers do not engage the specific topics of our essay. The author's article attempted to review the most comprehensive relational thinkers of that time across theoretical variables. Relationalists have begun to spell out the technical consequences of their perspective in recent discussions of neutrality, authority, and self-disclosure, among other issues. This is a useful trend in the relational literature, and we hope it continues. We are concerned, however, that the relational thinkers writing in this issue tend to dismiss the contributions to PP 12(1) because the perspectives presented there did not satisfy the relationalist vision of how scientific exchange should be undertaken. Although we feel that it is important for emerging points of view to be able to elaborate assumptions, constructs, and principles within their own framework and in their own way, constructive dialogue, much less a comparative analysis of the contributions and limitations of different points of view, requires that we have some common ground. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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