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   206731篇
  免费   2217篇
  国内免费   567篇
电工技术   3524篇
综合类   141篇
化学工业   31930篇
金属工艺   10316篇
机械仪表   7021篇
建筑科学   4003篇
矿业工程   2161篇
能源动力   4641篇
轻工业   12918篇
水利工程   2926篇
石油天然气   7727篇
武器工业   22篇
无线电   21572篇
一般工业技术   45288篇
冶金工业   34560篇
原子能技术   6626篇
自动化技术   14139篇
  2021年   2063篇
  2019年   1999篇
  2018年   3684篇
  2017年   3721篇
  2016年   4006篇
  2015年   2237篇
  2014年   3791篇
  2013年   8761篇
  2012年   5698篇
  2011年   7242篇
  2010年   5876篇
  2009年   6506篇
  2008年   6636篇
  2007年   6512篇
  2006年   5587篇
  2005年   5142篇
  2004年   4651篇
  2003年   4571篇
  2002年   4386篇
  2001年   4497篇
  2000年   4200篇
  1999年   4216篇
  1998年   10250篇
  1997年   7223篇
  1996年   5531篇
  1995年   4149篇
  1994年   3618篇
  1993年   3850篇
  1992年   2988篇
  1991年   3003篇
  1990年   2895篇
  1989年   2858篇
  1988年   2876篇
  1987年   2517篇
  1986年   2572篇
  1985年   2859篇
  1984年   2689篇
  1983年   2556篇
  1982年   2302篇
  1981年   2269篇
  1980年   2347篇
  1979年   2360篇
  1978年   2385篇
  1977年   2489篇
  1976年   2880篇
  1975年   2191篇
  1974年   2068篇
  1973年   2166篇
  1972年   1941篇
  1971年   1755篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
This paper presents a model of heterogenous diffusion in capillary porous materials during the process of drying. The governing heat and mass transfer equations have been established using the liquid as well as vapor flow. Two models have been presented. Model 1 does not consider the heat conduction while the model 2 has been established by considering the conduction. The developed models and the numerical solutions of the resulting differential equations can take into account the moisture and temperature dependent thermophysical properties of the product. All equations have been established in spherical coordinates but the programme written for the purpose of calculations can be used for other geometries also. Numerical calculations have been performed for gas concrete and tiles using model 1, while model 2 has been used for gas concrete only because of the lack of data for thermophysical properties of the tile. For gas concrete it was seen that conduction has only marginal effect on the drying process and the numerical predictions of the drying process were reasonably accurate.  相似文献   
33.
The effectiveness of the hybrid system sonication followed by wet oxidation (SONIWO) to treat otherwise refractory waste has been demonstrated. In such a hybrid system homogeneous CuSO4 catalyst was found to be very efficient.  相似文献   
34.
The technological process of cold forging applied for the first time in the production of the casing of the internal joint with races is described. The process operations of cold forging and the annealing and carburizing regimes for this part me described.  相似文献   
35.
Gilbenclamide, a widely used potent hypoglycaemic agent was solubllized using β -Cyclodextrin and β -Cyclodextrin derivatives. Complexes were prepared by kneading method in a molar ratio of 1:1 of the drug and the cyclodextrlns respectively. The Glibenclamide β -Cyelocextrin complex was characterized and evaluated by I.R. studies, Differential Scanning Calorimotry 6 X-ray diffractometry. The in-vitro dissolution rates of drug from inclusion complexes of β Cyclodextrins and its derivatives were compared. A significant Improvement In dissolution lor, rates of Gllbenclamide was observed with Inclusion complexes of all the Cyclodextrins. However, the solubilizing effect was more in case of β-Cyclodextrin derivatives.  相似文献   
36.
A distributed problem solving system can be characterized as a group of individual cooperating agents running to solve common problems. As dynamic application domains continue to grow in scale and complexity, it becomes more difficult to control the purposeful behavior of agents, especially when unexpected events may occur. This article presents an information and knowledge exchange framework to support distributed problem solving. From the application viewpoint the article concentrates on the stock trading domain; however, many presented solutions can be extended to other dynamic domains. It addresses two important issues: how individual agents should be interconnected so that their resources are efficiently used and their goals accomplished effectively; and how information and knowledge transfer should take place among the agents to allow them to respond successfully to user requests and unexpected external situations. The article introduces an architecture, the MASST system architecture, which supports dynamic information and knowledge exchange among the cooperating agents. The architecture uses a dynamic blackboard as an interagent communication paradigm to facilitate factual data, business rule, and command exchange between cooperating MASST agents. The critical components of the MASST architecture have been implemented and tested in the stock trading domain, and have proven to be a viable solution for distributed problem solving based on cooperating agents  相似文献   
37.
Translated from Atomnaya Énergiya, Vol. 66, No. 6, pp. 423–424, June, 1989.  相似文献   
38.
Translated from Atomnaya Énergiya, Vol. 67, No. 3, pp. 215–216, September, 1989.  相似文献   
39.
Geomechanical aspects of the storage of radioactive waste in salt formations have been studied extensively using finite element methods over the last 20 years. In consequence a range of computer programs and associated modelling techniques have been assembled. The paper is based on a benchmark exercise to compare the predictive abilities of a number of these programs and highlights the difficulties of making reliable a-priori estimates of long term behaviour.  相似文献   
40.
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