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   249038篇
  免费   1665篇
  国内免费   265篇
电工技术   4039篇
综合类   91篇
化学工业   40332篇
金属工艺   15144篇
机械仪表   10061篇
建筑科学   4176篇
矿业工程   3759篇
能源动力   3872篇
轻工业   9704篇
水利工程   4087篇
石油天然气   13006篇
武器工业   28篇
无线电   20200篇
一般工业技术   62755篇
冶金工业   32146篇
原子能技术   11135篇
自动化技术   16433篇
  2021年   2756篇
  2019年   2733篇
  2018年   5432篇
  2017年   5711篇
  2016年   6044篇
  2015年   3051篇
  2014年   5322篇
  2013年   10088篇
  2012年   7305篇
  2011年   8927篇
  2010年   7295篇
  2009年   8104篇
  2008年   8172篇
  2007年   7856篇
  2006年   6358篇
  2005年   5565篇
  2004年   5480篇
  2003年   5299篇
  2002年   5134篇
  2001年   4948篇
  2000年   4942篇
  1999年   4254篇
  1998年   7175篇
  1997年   5836篇
  1996年   4422篇
  1995年   3654篇
  1994年   3424篇
  1993年   3624篇
  1992年   3214篇
  1991年   3360篇
  1990年   3481篇
  1989年   3370篇
  1988年   3269篇
  1987年   3260篇
  1986年   3157篇
  1985年   3317篇
  1984年   3252篇
  1983年   3146篇
  1982年   2994篇
  1981年   3045篇
  1980年   3071篇
  1979年   3257篇
  1978年   3490篇
  1977年   3460篇
  1976年   3911篇
  1975年   3209篇
  1974年   3294篇
  1973年   3341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 0 毫秒
991.
Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 1, pp. 51–53, January–February, 1992.  相似文献   
992.
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   
993.
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   
994.
995.
The uniaxial bianisotropic medium is a generalisation of the bi-isotropic and chiral media which recently have been subject to intensive research. Such a medium results, for example, when microscopic helices with parallel axes are positioned in a host dielectric in random locations. Plane wave propagation in such a medium is studied and a simple solution for the dispersion equation is found. Numerical examples for the wave number surfaces of the medium are given.<>  相似文献   
996.
997.
998.
The results are presented of experimental examination of the effect of the grain size on the spoliation of copper. Levels of the loading pressure, corresponding to various stages of spollation, were determined for two initial states characterized by a mean grain size of 0.29 and 1.62 mm. The results show that for the material with the smaller grain these levels are approximately 0.2 GPa higher than for the material with the larger grain size.Translated from Problemy Prochnosti, No. 2, pp. 73–75, February, 1996.  相似文献   
999.
A statistically admissible solution has been constructed for a pipe with an axial through crack. The boundaries of the limit region have been obtained and the strength conditions on its boundary have been formulated. The extension of the distribution of forces and moments beyond the limit region boundary has been substantiated. The results obtained for a pipe with closed ends are in fair agreement with the experimental data. The influence of the axial force and the property anisotropy upon the fracture stress has been studied. The possibility of considering several cracks is analysed.  相似文献   
1000.
A method of calculating the response of sensitive elements based on wave delay devices is described using as an example a gauge for measuring the diameter of holes in metal objects. The efficiency of a sensitive element consisting a cylindrical helix with a longitudinally conducting shield is demonstrated. Translated from Izmeritel'naya Tekhnika, No. 9, pp. 46–50, September, 1996.  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