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   241302篇
  免费   2627篇
  国内免费   427篇
电工技术   4297篇
综合类   257篇
化学工业   39380篇
金属工艺   9380篇
机械仪表   7396篇
建筑科学   5448篇
矿业工程   1391篇
能源动力   5154篇
轻工业   24812篇
水利工程   2476篇
石油天然气   5092篇
武器工业   32篇
无线电   25046篇
一般工业技术   44779篇
冶金工业   45361篇
原子能技术   5950篇
自动化技术   18105篇
  2021年   2109篇
  2019年   2018篇
  2018年   3490篇
  2017年   3426篇
  2016年   3687篇
  2015年   2238篇
  2014年   3901篇
  2013年   10187篇
  2012年   6147篇
  2011年   8299篇
  2010年   6548篇
  2009年   7235篇
  2008年   7585篇
  2007年   7713篇
  2006年   6890篇
  2005年   6046篇
  2004年   5816篇
  2003年   5598篇
  2002年   5675篇
  2001年   5561篇
  2000年   5384篇
  1999年   5305篇
  1998年   12582篇
  1997年   8898篇
  1996年   6857篇
  1995年   5329篇
  1994年   4736篇
  1993年   4625篇
  1992年   3667篇
  1991年   3388篇
  1990年   3593篇
  1989年   3472篇
  1988年   3303篇
  1987年   2895篇
  1986年   2932篇
  1985年   3373篇
  1984年   3219篇
  1983年   2892篇
  1982年   2738篇
  1981年   2821篇
  1980年   2720篇
  1979年   2624篇
  1978年   2684篇
  1977年   2948篇
  1976年   3805篇
  1975年   2368篇
  1974年   2243篇
  1973年   2376篇
  1972年   1970篇
  1971年   1859篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
It has been demonstrated previously (see E.L. Ritman and A.A. Bove, in State of the Art in Quantitative Coronary Arteriography, p.67-78, 1986) that coronary artery anatomy can be visualized using high-speed, volume-scanning X-ray CT (computed tomography). In the current study it is demonstrated that local image reconstruction (i.e. the reconstruction kernel is ~2(+) mm long), as distinct from more conventional global image reconstruction (i.e. 200(+) mm kernel length), has the advantage of reducing the need for operator interactive image processing. In addition, the local reconstruction algorithm eliminates the need for recording the X-ray projection data over the full transaxial extent of the thorax because it requires only the X-ray attenuation data over the region of the heart. This latter aspect reduces the dynamic range requirements for the sensors and could reduce total X-ray exposure.  相似文献   
992.
1.  The suggestions on calculating the strength of concrete joints with transverse reinforcements were made on the basis of using the method of secondary stress fields and permit more complete consideration of the effect of the characteristics of the stress state on the strength of massive members.
2.  Unlike the preceding developments, the present suggestions make it possible to evaluate the reinforcement and concrete strength of the structural member being designed with pin resistance of the transverse bar reinforcement to the effect of the initial and secondary shear stresses in the longitudinal joint.
3.  The installation of an additional amount of transverse reinforcement precludes the probability of separation of the massive member along the longitudinal block joint and provides reliable and safe operation of the structure.
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 3, pp. 46–49, March, 1990.  相似文献   
993.
1.  Investigations showed that when constructing dams of fine-grained silty soils by hydraulic filling, it is expedient to use the technology of layerwise placement of soil with consolidation of each layer.
2.  Dependences are given for calculating the thickness of the layers and period of consolidation of the soil on the basis of investigations of the dynamics of the hydrophysical properties of these soils in relation to technological factors.
3.  Dependences are also proposed for predicting the density of the hydraulic-filled soil during construction, as well as the distribution of soil in the profile of the structure.
4.  A method is proposed for calculating the technological parameters, in particular, the rate of construction of hydraulic-fill structures, calculating the size and number of the hydraulic-fill plots referred to one dredge, and prediction of the seepage discharge into the foundation of the dams during their hydraulic filling.
5.  The proposed calculation methods make possible a more substantiated approach to the design of hydraulic-fill structures of fine-grained silty soils and technology of their construction.
Translated from Gidrotekhicheskoe Stroitel'stvo, No. 6, pp. 5–9, June, 1990.  相似文献   
994.
Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 2, pp. 31–32, February, 1990.  相似文献   
995.
Previous elevated-temperature experiments on 304 stainless steel clearly show that the density of dislocations within the subgrain interior influences the flow stress at a given strain rate and temperature. A re-evaluation shows that the hardening is consistent with the Taylor relation if a linear superposition of solute hardening ( 0, or the stress necessary to cause dislocation motion in the absence of a dislocation substructure) and dislocation (Gb 1/2) hardening is assumed. The same Taylor relation is applicable to steady-state structures of aluminium if the yield stress of annealed aluminium is assumed equal to 0. New tests on aluminium deforming under constant-strain-rate creep conditions show a monotonic increase in the dislocation density with strain. This and the constant-stress creep trends are shown to be possibly consistent with Taylor hardening.  相似文献   
996.
Programming and Computer Software - This paper investigates the implementation of virtual networks on the SDN data plane modeled by a graph of physical connections between network nodes. A virtual...  相似文献   
997.
Programming and Computer Software - We define a problem of certifying computation integrity performed by some remote party we do not necessarily trust. We present a multi-party interactive protocol...  相似文献   
998.
Programming and Computer Software - In the biomedical domain, diagrammatical models have been extensively used to describe and understand the behaviour of biological organisms (biological agents)...  相似文献   
999.
The Journal of Supercomputing - In this paper, we propose a parallel source separation system designed to extract heart and lung sounds from single-channel mixtures. The proposed system is based on...  相似文献   
1000.
The Journal of Supercomputing - General-purpose graphics processing units (GPGPUs) are extensively used in high-performance computing. However, it is well known that these devices’...  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