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   249922篇
  免费   1841篇
  国内免费   273篇
电工技术   4065篇
综合类   93篇
化学工业   40541篇
金属工艺   15174篇
机械仪表   10086篇
建筑科学   4179篇
矿业工程   3760篇
能源动力   3903篇
轻工业   9744篇
水利工程   4089篇
石油天然气   13010篇
武器工业   28篇
无线电   20382篇
一般工业技术   62960篇
冶金工业   32262篇
原子能技术   11140篇
自动化技术   16620篇
  2021年   2790篇
  2019年   2755篇
  2018年   5459篇
  2017年   5741篇
  2016年   6086篇
  2015年   3076篇
  2014年   5354篇
  2013年   10134篇
  2012年   7351篇
  2011年   8992篇
  2010年   7335篇
  2009年   8148篇
  2008年   8223篇
  2007年   7900篇
  2006年   6389篇
  2005年   5593篇
  2004年   5501篇
  2003年   5319篇
  2002年   5168篇
  2001年   4969篇
  2000年   4953篇
  1999年   4277篇
  1998年   7214篇
  1997年   5859篇
  1996年   4448篇
  1995年   3673篇
  1994年   3437篇
  1993年   3645篇
  1992年   3237篇
  1991年   3377篇
  1990年   3493篇
  1989年   3376篇
  1988年   3280篇
  1987年   3264篇
  1986年   3164篇
  1985年   3318篇
  1984年   3258篇
  1983年   3149篇
  1982年   2999篇
  1981年   3052篇
  1980年   3079篇
  1979年   3259篇
  1978年   3499篇
  1977年   3464篇
  1976年   3916篇
  1975年   3213篇
  1974年   3294篇
  1973年   3341篇
  1972年   2988篇
  1971年   2755篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
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   
102.
The Raman spectrum of water adsorbed on a metallic silver surface reveals an anomalously large shift of the vibrational frequency as compared to that in the bulk. The results are compared to data reported by other researchers, and possible interpretations of the observed phenomenon are discussed.  相似文献   
103.
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   
104.
X-ray diffraction analysis has been used to study the structure of the α-Zr matrix phase and the precipitation of β-Nb particles upon the annealing of a Zr–2.5% Nb deformed alloy. It has been found that the process of the precipitation of the strengthening β-Nb particles in the alloy is accompanied by the appearance of fields of elastic interphase deformations in the matrix α phase of the alloy due to the difference in the specific atomic volumes of the crystal structures of the matrix and precipitated phases. It has been shown experimentally that, as a result of the presence of interphase deformations in the alloy, the bcc crystal structure of the precipitating β-Nb particles undergoes monoclinic distortions.  相似文献   
105.
106.
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   
107.
Sidorov  G. V.  Myasoedov  N. F. 《Radiochemistry》2020,62(2):260-263
Radiochemistry - Reaction of solid-phase catalytic heterogeneous isotope exchange of 2-deoxy-D-glucose and its derivative, O(6)-(4-bromothiophenyl)guanine-C8-β-D-glucose with tritium has been...  相似文献   
108.
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   
109.
Hydrogen fuel is a promising alternative to fossil fuels because of its energy content, clean nature, and fuel efficiency. However, it is not readily available. Most current producion processes are very energy intensive and emit carbon dioxide. Therefore, this article reviews technological options for hydrogen production that are eco-friendly and generate clean hydrogen fuel. Biological methods, such different fermentation processes and photolysis are discussed together with the required substrates and the process efficiency.  相似文献   
110.
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   
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