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   170120篇
  免费   1350篇
  国内免费   194篇
电工技术   2573篇
综合类   121篇
化学工业   26719篇
金属工艺   9494篇
机械仪表   5745篇
建筑科学   3096篇
矿业工程   1890篇
能源动力   2732篇
轻工业   8903篇
水利工程   2739篇
石油天然气   8697篇
武器工业   12篇
无线电   14622篇
一般工业技术   38468篇
冶金工业   28616篇
原子能技术   6944篇
自动化技术   10293篇
  2018年   2994篇
  2017年   3109篇
  2016年   3364篇
  2015年   1687篇
  2014年   2982篇
  2013年   6421篇
  2012年   4348篇
  2011年   5446篇
  2010年   4471篇
  2009年   4936篇
  2008年   4994篇
  2007年   4922篇
  2006年   4189篇
  2005年   3855篇
  2004年   3680篇
  2003年   3562篇
  2002年   3487篇
  2001年   3495篇
  2000年   3389篇
  1999年   3253篇
  1998年   7097篇
  1997年   5234篇
  1996年   3873篇
  1995年   2961篇
  1994年   2629篇
  1993年   2759篇
  1992年   2290篇
  1991年   2319篇
  1990年   2448篇
  1989年   2336篇
  1988年   2347篇
  1987年   2216篇
  1986年   2274篇
  1985年   2322篇
  1984年   2246篇
  1983年   2176篇
  1982年   2013篇
  1981年   2231篇
  1980年   2070篇
  1979年   2299篇
  1978年   2452篇
  1977年   2444篇
  1976年   3121篇
  1975年   2267篇
  1974年   2330篇
  1973年   2369篇
  1972年   2177篇
  1971年   1923篇
  1970年   1720篇
  1969年   1643篇
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
91.
The influence of the temperature gradient over the thickness of the cladding of a fuel element of a fast-neutron reactor on the migration of point defects formed in the cladding material due to neutron irradiation has been studied. It has been shown that, under the action of the temperature gradient, the flux of vacancies onto the inner surface of the cladding is higher than the flux of interstitial atoms, which leads to the formation of a specific concentration profile in the cladding with a vacancy-depleted zone near the inner surface. The experimental results on the spatial distribution of pores over the cladding thickness have been presented with which the data on the concentration profiles and vacancy fluxes have been compared.  相似文献   
92.
The behavior of a superelastic Cu?14.2% Al?4%Ni single crystal in the case of high reversible strains under a longitudinal bending force was investigated. The effect of strain confinement along the crystal length was revealed and studied. The highest reversible strains (up to 10%) were shown to be confined within the central part of the bent crystal.  相似文献   
93.
The molten salt method was used to synthesise the MAX phase compounds Ti2AlC and Ti3AlC2 from elemental powders. Between 900–1000?°C, Ti2AlC was formed alongside ancillary phases TiC and TiAl, which decreased in abundance with increasing synthesis temperature. Changing the stoichiometry and increasing the synthesis temperature to 1300?°C resulted in formation of Ti3AlC2 alongside Ti2AlC and TiC. The type of salt flux used had little effect on the product formation. The reaction pathway for Ti2AlC was determined to be the initial formation of TiC1-x templating on the graphite and titanium aluminides.  相似文献   
94.
95.
Technical Physics Letters - A new method for epitaxial growth of cadmium sulfide (CdS) films in the metastable cubic phase by atomic-layer deposition on silicon substrates with a buffer layer of...  相似文献   
96.
Russian Engineering Research - The theoretically possible reconfigurable parallel mechanisms are classified, in terms of the layout of guides on the base. Formulas are derived for the...  相似文献   
97.
Programming and Computer Software - In this paper, we overview the approaches and techniques employed by the Svace static analysis tool for intraprocedural analysis. This analysis implies the...  相似文献   
98.
99.
The microstructure and properties of the functional coatings formed by impact friction processing of product surfaces with a flexible tool are studied. It is established that the processing produces a hard nanostructured surface layer with fragments up to 0.13 µm in size, as it is achieved by severe plastic deformation.  相似文献   
100.
The aim of the present contribution is to study the influence of the post-spinning heat - treatment of single TiO2/PVP precursor fibers on the properties and morphology of the final titanium-based microfibers. The post-spinning treatment conditions were: calcination in air at 450–600?°C and pyrolysis in argon at 1000–1700?°C. Calcination resulted in a production of anatase-rich and pure rutile fibers. The use of an alternative sintering method, the low-temperature plasma treatment, led to the crystallization of the composite Magnéli phases/polymer fibers. As a result of the same one precursor, pyrolysis at 1000?°C, the Carbon/TiO2 composite fibers were obtained. Rising the treatment temperature in inert atmosphere led to the formation of the titanium carbide fibers. The formation process and all the obtained products were characterized by differential scanning calorimetry accompanied with thermogravimetric analysis (DSC/TGA), scanning and transmission electron microscopy (SEM, TEM), X-ray diffraction (XRD), and image analysis techniques.  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