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   1383篇
  免费   11篇
  国内免费   1篇
电工技术   42篇
化学工业   240篇
金属工艺   105篇
机械仪表   123篇
建筑科学   44篇
矿业工程   8篇
能源动力   11篇
轻工业   65篇
水利工程   18篇
石油天然气   34篇
无线电   83篇
一般工业技术   279篇
冶金工业   209篇
原子能技术   30篇
自动化技术   104篇
  2022年   25篇
  2021年   43篇
  2020年   21篇
  2019年   30篇
  2018年   59篇
  2017年   59篇
  2016年   64篇
  2015年   36篇
  2014年   57篇
  2013年   83篇
  2012年   66篇
  2011年   107篇
  2010年   76篇
  2009年   91篇
  2008年   96篇
  2007年   92篇
  2006年   69篇
  2005年   30篇
  2004年   18篇
  2003年   5篇
  2002年   9篇
  2001年   7篇
  2000年   27篇
  1999年   23篇
  1998年   38篇
  1997年   39篇
  1996年   16篇
  1995年   14篇
  1994年   4篇
  1993年   4篇
  1992年   4篇
  1991年   6篇
  1990年   6篇
  1989年   2篇
  1988年   2篇
  1987年   2篇
  1985年   7篇
  1984年   4篇
  1982年   5篇
  1981年   6篇
  1980年   3篇
  1978年   2篇
  1977年   4篇
  1976年   15篇
  1975年   5篇
  1973年   4篇
  1972年   2篇
  1970年   1篇
  1968年   1篇
  1966年   2篇
排序方式: 共有1395条查询结果,搜索用时 9 毫秒
1.
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   
2.
A technology for the synthesis of synthetic minerals (using the example of spinels) using a low-temperature plasma flame is developed. The diagnostic properties of spinels are identified.  相似文献   
3.
Studies on the influence of anthracene coal extracts on the carbonization process of medium- and high-rank coals were undertaken. Extracts from flame coal (Int. Class. 900) and gas-coking coal (Int. Class. 632) were used as additives. The blends prepared from the examined coals and the extracts exhibited better coking properties than the parent coals. The addition of extract to the coals gave an increase in the microstrength of the resultant cokes. The effects of co-carbonization of coking coals with extracts were increases in the size of the optical texture as well as in the degree of structural ordering of cokes. In the co-carbonization of semicoking coal with addition of coal extracts, a reduction in the size of the anisotropic units and a decrease in the crystallite height of cokes were observed. No modification of the basic anisotropy of coke from anthracite by coal extract was observed. With increasing extract content in anthracite/extract blends there was an increase in the degree of structural ordering of co-carbonization products. Extract addition was unable to modify the behaviour of fusinite. Based on the results of investigation of the influence of coal extracts on the carbonization of different-rank coals, a division of coals according to the modification of the optical texture of coke is given.  相似文献   
4.
5.
Methods for cleaning commercial T-1500 dielectric oil with different adsorbents are studied. The oil is intended for impregnation of high-voltage pulse capacitors with film dielectric.  相似文献   
6.
This work is devoted to the development and substantiation of intellectual data mining as applied to studying folklore and mythological traditions. The approach is based on use of the functions of distance between traditions. The examples of application of the methods developed to investigate the interrelation between folklore traditions of the American continent are considered.  相似文献   
7.
A technique for measuring the charges of relativistic nuclei in thick emulsion layers irradiated in a longitudinal direction is described. This technique has been implemented on the PAVICOM completely automated facility at the Lebedev Physical Institute. The calibration curves for relativistic nuclei with Z > 3 are presented. The advantages of this technique are demonstrated using charge measurements of 28Si nuclear fragments as an example.  相似文献   
8.
We propose a method for constructing ensembles of regression models and perform its theoretical and experimental analysis.  相似文献   
9.
10.
The residual protective effect of n-component mixtures of o-oxyazomethine derivatives at the corrosion of iron in 1 M H2SO4 decreases with time and an increase in temperature of the environment and increases with an increase in the polarity of substituent groups in the molecules and the inhibitor concentration in the solution. These regularities are interpreted based on the principle of the linear free-energy relation.  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