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   249041篇
  免费   1665篇
  国内免费   265篇
电工技术   4041篇
综合类   91篇
化学工业   40321篇
金属工艺   15146篇
机械仪表   10066篇
建筑科学   4176篇
矿业工程   3759篇
能源动力   3874篇
轻工业   9697篇
水利工程   4087篇
石油天然气   13007篇
武器工业   28篇
无线电   20193篇
一般工业技术   62760篇
冶金工业   32158篇
原子能技术   11134篇
自动化技术   16433篇
  2021年   2755篇
  2019年   2731篇
  2018年   5428篇
  2017年   5709篇
  2016年   6044篇
  2015年   3051篇
  2014年   5323篇
  2013年   10081篇
  2012年   7303篇
  2011年   8927篇
  2010年   7294篇
  2009年   8105篇
  2008年   8173篇
  2007年   7856篇
  2006年   6360篇
  2005年   5566篇
  2004年   5480篇
  2003年   5300篇
  2002年   5134篇
  2001年   4948篇
  2000年   4940篇
  1999年   4255篇
  1998年   7174篇
  1997年   5832篇
  1996年   4425篇
  1995年   3661篇
  1994年   3424篇
  1993年   3625篇
  1992年   3214篇
  1991年   3363篇
  1990年   3483篇
  1989年   3373篇
  1988年   3270篇
  1987年   3261篇
  1986年   3157篇
  1985年   3317篇
  1984年   3252篇
  1983年   3147篇
  1982年   2997篇
  1981年   3045篇
  1980年   3072篇
  1979年   3258篇
  1978年   3490篇
  1977年   3460篇
  1976年   3911篇
  1975年   3209篇
  1974年   3294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 15 毫秒
951.
The testing procedure and the results of tests performed on a 19-element fragment of a VVéR-1000 fuel assembly in the channel of a MIR reactor under conditions of the second and third stage of a maximum anticipated accident are presented. The state arising in the reactor core with an uncompensated leak arising in the first cooling loop when a pipeline with the maximum diameter bursts (large leak) is studied in the experiment. In each case study, superheated steam cools the top part of the fuel elements. The main goal of the tests is to obtain data on the distortion of fuel-element cladding under tensile stresses. __________ Translated from Atomnaya énergiya, Vol. 103, No. 5, pp. 286–291, November, 2007.  相似文献   
952.
953.
A method of linearization with respect to the useful signal of relay systems with the control plant containing blocks with limiters is proposed. Relay systems with two-position relay element are considered. The method allows studying the tracking mode of input signals in the relay system in a simple way. This is very important for synthesizing relay systems when a great number of variants need to be analyzed.  相似文献   
954.
The mechanical properties of hard WC-Co alloys produced by solid-phase sintering at various temperatures are discussed. It is shown that the bending strength and hardness of these alloys may be the same as those achieved in liquid-phase sintering. The difference between solid-phase and liquid-phase sintering is only in the time it takes to achieve the dense state. Excellent mechanical properties at rather low temperatures (1150–1200 °C) can be obtained by sintering under pressure. High hardness can be achieved at 1000–1100 °C by hot isostatic pressing of nanoscale powders. The excellent mechanical properties of solid-phase-sintered hard WC-Co alloys indicate that strong interphase and intercarbide boundaries occur earlier than the liquid phase.  相似文献   
955.
With the use of Volterra functional expansions in the domain of the multidimensional z transform, discrete uniform-sampling analogues of digital phase-locked loops of the first, second, and (N + 2)th orders with a delay of N sampling periods are analyzed.  相似文献   
956.
957.
Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 1, pp. 51–53, January–February, 1992.  相似文献   
958.
Ultrathin dielectric materials that provide high capacitance values are needed for 64- and 256-Mb stacked DRAMs. It is shown that capacitance values as high as 12.3 fF/μm2 can be obtained with ultrathin nitride-based layers deposited on rugged polysilicon storage electrodes. These films present the reliability and low leakage current levels required for 3.3-V applications. The nitride thickness, however, cannot be scaled much below 6 nm to avoid the oxidation-punchthrough mechanisms that appear when too-thin films are unable to withstand the reoxidation step  相似文献   
959.
In order to produce mAbs directed specifically against HLA-DR10 molecule, transfected mouse L cells, expressing the DRB1*1001 allele, were used to immunize C3H mice over a period of 4 weeks. Two mAbs, 2C12 and 4B6, derived from this fusion were found to recognize, with different affinity, polymorphic epitopes of DR10 that are shared with DR1, 3, 7, and 9. These mAbs were screened on a large panel of homozygous B lymphoblastoid cell lines using microlymphocytotoxicity and the results were confirmed by flow cytometry. The reactive pattern of 2C12 and 4B6 was compared to that of MP10 human mAb also recognizing the DR10 specificity in addition to DR1, 2 and 9. Based on serologic specificity and cellular absorption experiments, we conclude that the epitopes the murine and human mAbs respectively recognize on the DR10 molecule, are probably different.  相似文献   
960.
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