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   5761篇
  免费   162篇
  国内免费   1篇
电工技术   58篇
综合类   5篇
化学工业   1049篇
金属工艺   116篇
机械仪表   75篇
建筑科学   217篇
矿业工程   4篇
能源动力   89篇
轻工业   534篇
水利工程   31篇
石油天然气   6篇
武器工业   1篇
无线电   377篇
一般工业技术   907篇
冶金工业   1954篇
原子能技术   58篇
自动化技术   443篇
  2022年   43篇
  2021年   65篇
  2020年   46篇
  2019年   51篇
  2018年   75篇
  2017年   75篇
  2016年   100篇
  2015年   100篇
  2014年   113篇
  2013年   162篇
  2012年   159篇
  2011年   190篇
  2010年   182篇
  2009年   147篇
  2008年   179篇
  2007年   147篇
  2006年   157篇
  2005年   112篇
  2004年   117篇
  2003年   128篇
  2002年   108篇
  2001年   126篇
  2000年   111篇
  1999年   150篇
  1998年   596篇
  1997年   374篇
  1996年   267篇
  1995年   147篇
  1994年   132篇
  1993年   146篇
  1992年   64篇
  1991年   52篇
  1990年   69篇
  1989年   66篇
  1988年   46篇
  1987年   49篇
  1986年   48篇
  1985年   41篇
  1984年   37篇
  1983年   42篇
  1982年   48篇
  1981年   53篇
  1980年   44篇
  1979年   45篇
  1978年   41篇
  1977年   108篇
  1976年   166篇
  1975年   39篇
  1972年   26篇
  1970年   27篇
排序方式: 共有5924条查询结果,搜索用时 15 毫秒
901.
902.
Quantifying the economic impact of psychological programs in organizations requires determination of (a) the size and variability of the resulting increase in job performance and (b) the economic value of the increase in job performance. New methods of meta-analysis allow attainment of the 1st of these; and in relation to the 2nd, utility analysis methods provide the ability to translate job performance increases into estimates of the economic value of the program. In the area of personnel selection, many meta-analytic studies have resulted in precise and generalizable estimates of the validity of cognitive ability tests and other selection procedures. Utility analyses show that the job performance increases resulting from use of valid selection methods have substantial economic value. Valid selection produces major increases in work-force productivity. It is concluded that the combined effects of selection and nonselection interventions can be expected to produce substantial increases in workforce productivity. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
903.
Microscopic cysts in the permanent cortices of adrenal glands were studied in a series of 274 infants, some of whom had been stillborn and none of whom were more than 12 months old. After correction for length of gestation, there were no significant relationships between the occurence and number of microcysts and various maternal, placental, and perinatal diseases. A significant direct correlation was demonstrated statistically with shorter gestational period and shorter survival time after birth. We concluded that the adrenal microcysts are either a developmental feature or the result of a greater susceptibility to stress in the fetus and newborn than in older infants.  相似文献   
904.
Orthogonal collocation techniques are used to simulate the solution to the hydrodynamic partial differential equations describing mass transport to a dropping mercury electrode (dme). Accurate values for the concentration profiles and current are obtained with minimal computational effort.  相似文献   
905.
A literature review indicates that the standard deviation of employee output averaged 20% of mean output under nonpiecework compensation systems and 15% under piecework systems. For both systems, variability around the mean was small. Implications for selection and workforce productivity are discussed. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
906.
907.
908.
909.
A report is given on the results of radiotherapy in 82 cases of labial carcinoma admitted to the Radiological Clinic, Jena. The absolute 5 years' healing for primary tumours is 73,25%. The absolute 5 year's healing for relapses is 68,9%. The absolute 5 years' healing for regional lymph node metastases is 21,8%.  相似文献   
910.
Generalized fin-lines are analyzed which consist of slots located on more than one interface between dielectric layers inserted in parallel with the E-plane of a waveguide. The analysis is based on a simplified formulation technique based on the spectral domain immittance matrix followed by a Galerkin's method. It allows as many slots as one desires at each interface, and the locations and the widths of these slots are arbitrary. The numerical process to carry out the present analysis is rather efficient. Some numerical data, including propagation constants of the propagating modes as well as characteristic impedances are presented for several structures considered useful for millimeter-wave circuit applications.  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