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   379549篇
  免费   4330篇
  国内免费   1092篇
电工技术   6615篇
综合类   287篇
化学工业   56730篇
金属工艺   17035篇
机械仪表   12088篇
建筑科学   8392篇
矿业工程   3156篇
能源动力   9296篇
轻工业   28234篇
水利工程   4824篇
石油天然气   10596篇
武器工业   28篇
无线电   41746篇
一般工业技术   78852篇
冶金工业   68036篇
原子能技术   10339篇
自动化技术   28717篇
  2021年   3513篇
  2019年   3307篇
  2018年   5747篇
  2017年   5856篇
  2016年   6248篇
  2015年   3745篇
  2014年   6289篇
  2013年   16588篇
  2012年   9927篇
  2011年   13191篇
  2010年   10615篇
  2009年   11969篇
  2008年   12176篇
  2007年   12166篇
  2006年   10400篇
  2005年   9659篇
  2004年   8972篇
  2003年   8826篇
  2002年   8370篇
  2001年   8514篇
  2000年   8185篇
  1999年   8357篇
  1998年   20567篇
  1997年   14512篇
  1996年   11332篇
  1995年   8368篇
  1994年   7481篇
  1993年   7487篇
  1992年   5814篇
  1991年   5679篇
  1990年   5366篇
  1989年   5387篇
  1988年   5256篇
  1987年   4573篇
  1986年   4544篇
  1985年   5196篇
  1984年   4851篇
  1983年   4550篇
  1982年   4087篇
  1981年   4164篇
  1980年   4079篇
  1979年   4148篇
  1978年   4137篇
  1977年   4520篇
  1976年   5685篇
  1975年   3693篇
  1974年   3524篇
  1973年   3633篇
  1972年   3111篇
  1971年   2872篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The article presents the results of experimental investigations of critical (limit) heat fluxes upon evaporation on porous coatings, and it substantiates the physical model of the process.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 4, pp. 607–614, October, 1985.  相似文献   
102.
Structures and compositions of the monomers guanidine acrylate and guanidine methacrylate, their homopolymers, and copolymers with diallyldimethylammonium chloride enriched in acrylate comonomer units were determined. It was shown that ampholytic copolymers, owing to their ionic nature, contained comonomeric guanidine acrylate or methacrylate units and diallyldimethylammonium chloride units, as well as the acrylate comonomer with the diallyl counterion and polymeric acrylate and diallyl ion pairs. It follows from IR and 1H NMR data that guanidine methacrylate has the same structure (with two hydrogen bonds) in the solid state and in solutions. Guanidine acrylate structures in the solid state and in dimethylsulfoxide are identical and analogous to guanidine methacrylate structure in this solvent. In water, the guanidine acrylate structure has another type of hydrogen bonding (with one hydrogen bond, where the proton is shifted toward the guanidine group). These features of hydrogen bonding of guanidine acrylate and guanidine methacrylate are also retained in their homopolymers and copolymers with diallyldimethylammonium chloride. It was shown that the thermal stability of the copolymers was higher than that of their homopolymers, confirming the formation of intramolecular ion pairs of oppositely charged units of ampholytic copolymers. Moreover, the thermal stability of guanidine methacrylate-diallyldimethylammonium chloride copolymers is higher than that of guanidine acrylate-diallyldimethylammonium chloride copolymers.  相似文献   
103.
Surface tension as a controlled variable in mechanical dishwashing   总被引:1,自引:0,他引:1  
Using a continuous, in-line, nondestructive technique based on the maximum bubble pressure method, the surface tension of the wash water in a mechanical dishwashing machine has been monitored. This technique has enabled surface tension to be used as a controlled variable, providing feedback to regulate the amount of surfactant added. Assuming the mechanical force of the water spray is adequate to remove bound soil from the dish surface, the food soil may be titrated against surfactant, providing an indirect indication as to when the dishes are clean. This technique also could be applied to a recirculated wash solution for in-place cleaning.  相似文献   
104.
Some methods determine the non-indolyl glucosinolates content in rapeseed as their hydrolysates: the isothiocyanates and the oxazolidinethiones. These methods in their present form underestimate the amount of the glucosinolates content. In this investigation, a modified method was developed to give a better quantitative estimate, indicating a glucosinolate level five times that obtained by a typical existing method.  相似文献   
105.
Alphorn, a software environment for programming distributed computer systems, is described. Programs running on different computers, possibly of different types and running different operating systems, communicate in a client-server relationship by means of remote procedure calls. This efficient construct structures programs neatly. The paper covers distributed process control, Alphorn's object-based programming style, remote procedure calls, the service interface language, configuration, runtime and debugging, and fault tolerance support  相似文献   
106.
107.
108.
109.
110.
Conclusions The change in some properties of polyvinyl fluoride during the process of fibre spinning has been investigated.It has been found that during the process of converting PVF powder into fibre, the degree of polymer crystallinity plus its resistance to thermal and thermooxidative degradation is increased; depending on the spinning regime, the densities and physicomechanical properties of PVF fibres are different.Translated from Khimicheskie Volokna, No. 4, pp. 34–35, July–August, 1984.  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