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   170959篇
  免费   1522篇
  国内免费   193篇
电工技术   2638篇
综合类   123篇
化学工业   27110篇
金属工艺   9522篇
机械仪表   5811篇
建筑科学   3112篇
矿业工程   1895篇
能源动力   2814篇
轻工业   9288篇
水利工程   2745篇
石油天然气   8706篇
武器工业   12篇
无线电   14656篇
一般工业技术   38961篇
冶金工业   27817篇
原子能技术   6939篇
自动化技术   10525篇
  2019年   1640篇
  2018年   3090篇
  2017年   3198篇
  2016年   3482篇
  2015年   1766篇
  2014年   3093篇
  2013年   6640篇
  2012年   4511篇
  2011年   5602篇
  2010年   4583篇
  2009年   5010篇
  2008年   5071篇
  2007年   4980篇
  2006年   4228篇
  2005年   3871篇
  2004年   3666篇
  2003年   3568篇
  2002年   3485篇
  2001年   3492篇
  2000年   3396篇
  1999年   3241篇
  1998年   7037篇
  1997年   5163篇
  1996年   3846篇
  1995年   2936篇
  1994年   2623篇
  1993年   2742篇
  1992年   2276篇
  1991年   2320篇
  1990年   2428篇
  1989年   2331篇
  1988年   2325篇
  1987年   2198篇
  1986年   2254篇
  1985年   2322篇
  1984年   2236篇
  1983年   2159篇
  1982年   2003篇
  1981年   2225篇
  1980年   2080篇
  1979年   2292篇
  1978年   2450篇
  1977年   2441篇
  1976年   3110篇
  1975年   2256篇
  1974年   2315篇
  1973年   2351篇
  1972年   2169篇
  1971年   1915篇
  1970年   1705篇
排序方式: 共有10000条查询结果,搜索用时 503 毫秒
91.
Equipment of the Krasnoyarsk HPP is considered as an example to analyze the dependence of crack formation in runner blades on the operating conditions of t  相似文献   
92.
93.
In this study, further analysis of the osmotic drying process was conducted to identify the optimum combination of parameters for drying rectangular alumina-gelatin beams. This study was designed to determine the effect of three variables related to the osmotic drying process (osmotic pressure, molecular weight, and immersion time) on the interaction between the liquid desiccant and the submerged alumina-gelatin samples. The water loss from the alumina-gelatin samples was positively correlated with the molecular weight, osmotic pressure, and immersion time. Up to 40% by weight of the initial water content was removed during the osmotic drying process. The samples also experienced solids gain due to the counterflow of solute from the liquid desiccant. The least amount of solids gain resulted from drying for the shortest immersion time at low osmotic pressure and high molecular weight. Evidence of possible interactions between variables was noted for the sintered density metric. Statistical methods were used to form regression equations for the measured responses (water loss, solids gain, bulk density). A verification experiment was conducted to compare the experimental outcomes to the predicted outcomes. The responses were simultaneously optimized to identify the combination of variable settings required to meet specified goals. In order to maximize water loss, minimize solids gain, and maximize bulk density, the ceramic-gelatin object should be immersed for approximately 60?min in an aqueous solution of 100,000?g/mol poly(ethylene oxide) at an osmotic pressure of 2.50?MPa. These values are valid for the range of parameter settings tested and the sample fabrication and drying methods used.  相似文献   
94.
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   
95.
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   
96.
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   
97.
98.
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   
99.
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   
100.
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   
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