首页 | 官方网站   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   210542篇
  免费   2557篇
  国内免费   569篇
工业技术   213668篇
  2021年   2088篇
  2019年   2052篇
  2018年   3745篇
  2017年   3774篇
  2016年   4073篇
  2015年   2313篇
  2014年   3859篇
  2013年   9070篇
  2012年   5868篇
  2011年   7432篇
  2010年   6014篇
  2009年   6658篇
  2008年   6825篇
  2007年   6713篇
  2006年   5758篇
  2005年   5291篇
  2004年   4789篇
  2003年   4699篇
  2002年   4511篇
  2001年   4556篇
  2000年   4269篇
  1999年   4298篇
  1998年   10255篇
  1997年   7261篇
  1996年   5604篇
  1995年   4207篇
  1994年   3669篇
  1993年   3918篇
  1992年   3066篇
  1991年   3022篇
  1990年   2944篇
  1989年   2905篇
  1988年   2907篇
  1987年   2559篇
  1986年   2627篇
  1985年   2931篇
  1984年   2779篇
  1983年   2609篇
  1982年   2353篇
  1981年   2332篇
  1980年   2392篇
  1979年   2439篇
  1978年   2431篇
  1977年   2549篇
  1976年   2925篇
  1975年   2240篇
  1974年   2119篇
  1973年   2224篇
  1972年   1983篇
  1971年   1772篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
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   
122.
123.
Programming and Computer Software - Modern computer systems often include specialized processors that are programmed in domain-specific languages. The compiler-in-the-loop technology, which assumes...  相似文献   
124.
This study addresses the thermo‐diffusion and the diffusion‐thermo phenomena in a semi‐infinite absorbent channel whose walls are contracting/expanding, with heat source/sink effects. The governing partial differential equations with suitable boundary conditions are transformed to a system of dimensionless ordinary differential equations. An analytic solution of the problem has been found using a technique called homotopy analysis method (HAM). HAM gives consistently valid answers to the problem over an extensive variety of parameters and also provides better accuracy. To validate the analytical results, a comparison has been presented with a numerical solution calculated by using the parallel shooting method. The effects of dimensionless parameters, that is, deformation parameter, Reynolds number, Soret and Dufour numbers, and heat source/sink parameter on the expressions of velocity, temperature, and concentration profiles are analyzed graphically to understand the physics of the deformable channel. It has been noted that the velocity across the channel is higher for the expanding channel, as compared to that for the contracting channel. Also the Soret and Dufour number increases the temperature of the fluid, and decreases the concentration. The temperature profile has an increasing behavior in the case of heat source, and a decreasing behavior in the case of heat sink.  相似文献   
125.
126.
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   
127.
128.
Based on the phase transformation theories, especially the T0 concept of bainite transformation, alloy optimisation of bainitic steel with carbides has been carried out aiming at the produce of plastic mould with large cross-section. The effect of manganese and silicon on proeutectoid ferrite and bainite transformation is explored by dilatometric analysis, XRD and different microscopy techniques. The results show that after the alloy optimisation, the transformation of proeutectoid ferrite is suppressed and when the cooling rate is lower than 0·1°C?s??1, the new lower bainite transformation appears by decreasing carbon capacity of austenite and promoting carbide precipitation. Industrial production proves that the optimised alloy SDP1 can meet the demand for the plastic mould with the thickness of 1050?mm.  相似文献   
129.
Journal of Computer and Systems Sciences International - The height of a building is a basic characteristic needed for analytical services. It can be used to evaluate the population and functional...  相似文献   
130.
Protection of Metals and Physical Chemistry of Surfaces - The possibility is shown of creating a chart of local corrosion damage in the walls of heat-exchange tubes on the basis of the data of...  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-23

京公网安备 11010802026262号