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   116036篇
  免费   2699篇
  国内免费   436篇
电工技术   1002篇
综合类   2332篇
化学工业   18009篇
金属工艺   5382篇
机械仪表   3715篇
建筑科学   3059篇
矿业工程   626篇
能源动力   1756篇
轻工业   9026篇
水利工程   1548篇
石油天然气   465篇
武器工业   5篇
无线电   10399篇
一般工业技术   21561篇
冶金工业   10576篇
原子能技术   399篇
自动化技术   29311篇
  2024年   77篇
  2023年   296篇
  2022年   382篇
  2021年   846篇
  2020年   688篇
  2019年   811篇
  2018年   15430篇
  2017年   14347篇
  2016年   11128篇
  2015年   1649篇
  2014年   1474篇
  2013年   2804篇
  2012年   5027篇
  2011年   10998篇
  2010年   9591篇
  2009年   6767篇
  2008年   7942篇
  2007年   8826篇
  2006年   960篇
  2005年   1913篇
  2004年   1795篇
  2003年   1754篇
  2002年   1123篇
  2001年   536篇
  2000年   593篇
  1999年   510篇
  1998年   2435篇
  1997年   1657篇
  1996年   1086篇
  1995年   638篇
  1994年   491篇
  1993年   572篇
  1992年   219篇
  1991年   231篇
  1990年   157篇
  1989年   158篇
  1988年   171篇
  1987年   140篇
  1986年   120篇
  1985年   142篇
  1984年   128篇
  1983年   94篇
  1982年   132篇
  1981年   148篇
  1980年   157篇
  1979年   83篇
  1978年   83篇
  1977年   280篇
  1976年   623篇
  1954年   68篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
A dozen CuO samples prepared under various conditions and from different starting materials were evaluated as cathode materials for a primary Li/CuO cell. The “thin electrode” method was used for rapid evaluation of the samples. Both coulombic efficiency and discharge voltage depend considerably on the method of synthesis. No correlation was found between the specific surface area and the resistivity of the samples on the one hand and the cathode performance on the other. Best results were obtained from CuO prepared by the oxidation of Cu2O under controlled temperature and time of oxidation.  相似文献   
74.
75.
76.
77.
The Vesilind settling velocity function forms the basis of flux theory used both in state point analysis (for design and capacity rating) and one-dimensional dynamic models (for dynamic process modelling). This paper proposes new methods to address known shortcomings of these methods, based on an extensive set of batch settling tests conducted at different scales. The experimental method to determine the Vesilind parameters from a series of bench scale settling tests is reviewed. It is confirmed that settling cylinders must be slowly stirred in order to represent settling performance of full scale plants for the whole range of solids concentrations. Two new methods to extract the Vesilind parameters from settling test series are proposed and tested against the traditional manual method. Finally, the same data set is used to propose an extension to one-dimensional (1-D) dynamic settler models to account for compression settling. Using the modified empirical function, the model is able to describe the batch settling interface independently of the number of layers.  相似文献   
78.
A new analytical method has been developed for the determination of the reactive lysine content of soya bean protein. The method is based on the reaction of the free basic groups of the protein with 1-phenylazo-2 naphthol-6,8 disulphonic acid. With regard to the stoichiometry of the procedure, it has been proved, contrary to earlier reports, that the basic amino acids, histidine, arginine and lysine, each combine with one mole of the dye. After acylation with propionic anhydride lysine alone loses its dye reactivity. The usefulness of the proposed method has been demonstrated by the determination of the reactive lysine content of several untreated, heat-treated and acid-treated soya bean samples. The results show that heat damage of about 5% in reactive lysine content can be measured in 1·5 h with good reproducibility.  相似文献   
79.
80.
Discusses the theoretical and clinical applications of the postmodern paradigm of social constructionism as a basis for counseling culturally different clients. Such applications avoid the trap of perpetuating the status-quo when working with minority and marginalized clientele. The main points of multiculturalism and social constructionism are summarized, and issues of mutual concern to both perspectives are examined. Applications to psychotherapy are explored, and the challenges of applying the social constructionist approach to culturally competent counseling are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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