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   1983篇
  免费   66篇
  国内免费   3篇
电工技术   29篇
综合类   2篇
化学工业   433篇
金属工艺   85篇
机械仪表   51篇
建筑科学   35篇
矿业工程   1篇
能源动力   112篇
轻工业   93篇
水利工程   18篇
石油天然气   8篇
无线电   244篇
一般工业技术   405篇
冶金工业   190篇
原子能技术   22篇
自动化技术   324篇
  2023年   16篇
  2022年   29篇
  2021年   38篇
  2020年   29篇
  2019年   43篇
  2018年   48篇
  2017年   41篇
  2016年   47篇
  2015年   43篇
  2014年   50篇
  2013年   119篇
  2012年   80篇
  2011年   117篇
  2010年   99篇
  2009年   86篇
  2008年   84篇
  2007年   91篇
  2006年   70篇
  2005年   59篇
  2004年   32篇
  2003年   47篇
  2002年   43篇
  2001年   34篇
  2000年   32篇
  1999年   36篇
  1998年   74篇
  1997年   60篇
  1996年   36篇
  1995年   37篇
  1994年   43篇
  1993年   27篇
  1992年   37篇
  1991年   37篇
  1990年   21篇
  1989年   25篇
  1988年   13篇
  1987年   12篇
  1986年   11篇
  1985年   21篇
  1984年   18篇
  1983年   26篇
  1982年   21篇
  1981年   19篇
  1980年   16篇
  1979年   12篇
  1978年   8篇
  1977年   13篇
  1975年   12篇
  1974年   11篇
  1973年   10篇
排序方式: 共有2052条查询结果,搜索用时 15 毫秒
111.
A few common spices or their active principles were examined for their possible influence on digestive enzymes of pancreas in experimental rat. Groups of animals were maintained for 8 weeks on the following spice diets: curcumin (0.5%), capsaicin (15 mg%), piperine (20 mg%), ginger (50 mg%), cumin (1.25%), fenugreek (2%), mustard (250 mg%) and asafoetida (250 mg%). Dietary curcumin, capsaicin, piperine, ginger, fenugreek and asafoetida prominently enhanced pancreatic lipase activity. Curcumin, capsaicin, piperine, ginger, cumin and asafoetida also stimulated pancreatic amylase. Trypsin was significantly stimulated by curcumin, capsaicin, piperine, ginger and cumin, while chymotrypsin was stimulated by all the spices tested except mustard. This stimulatory influence of test spices on the pancreatic digestive enzymes was however not observed when their intake was restricted to a single oral dose. The positive influences on the pancreatic digestive enzymes exerted by a good number of spices consumed in diet could be a factor contributing to the well recognised digestive stimulant action of spices.  相似文献   
112.
Developed 2 admissions models to predict future academic performance of graduate management students. The 1st model was based on 40 students who were admitted and enrolled in the program and was uncorrected for curtailment. The 2nd model was developed from the total applicant population of 222 students after curtailment correction. The corrected model demonstrated higher predictive validity than the uncorrected model for 2 future classes of students. Furthermore, different predictors entered each model, affecting the beta weights, validities of predictors, and the total amount of variance explained by the models. A factor analysis and an analysis of admissions decisions offer additional support for the curtailment-corrected model in selecting students with high academic potential. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
113.
114.
115.
The application of hollow and filament-filled single asymmetric membrane fibers, consisting of a thin silicone layer on a tubular microporous support, for removing CO(2) in suppressed ion chromatography effluents is described. With appropriate choice of the removal device and operating conditions, the CO(2) can be essentially quantitatively (99+%) removed. For carbonate-based eluents, the use of such devices greatly reduces or eliminates the water dip, permitting better quantitation of poorly retained anions that elute close to the dip, allows practical gradient chromatography, and improves noise levels and attainable detection limits. In hydroxide eluent chromatography, the device largely removes the response from CO(2) present in the samples; this greatly aids atmospheric trace gas analysis by IC. Device dimensions are such that the dispersion introduced by the device is small.  相似文献   
116.
Summary The present paper describes the grafting of vinyl monomers onto cellulose nitrate in non-aqueous medium using benzoyl peroxide as a catalyst. The complete separation of the homopolymers and graft copolymer was carried out by selective solvent extraction. The graft copolymer was characterized by IR spectra. The GPC was used as a technique to differentiate between homopolymer, polymer mixture, polyblend, and graft copolymer.  相似文献   
117.
118.
119.
Recently, several algorithms have been proposed to enhance noisy speech by estimating a binary mask that can be used to select those time-frequency regions of a noisy speech signal that contain more speech energy than noise energy. This binary mask encodes the uncertainty associated with enhanced speech in the linear spectral domain. The use of the cepstral transformation smears the information from the noise dominant time-frequency regions across all the cepstral features. We propose a supervised approach using regression trees to learn the nonlinear transformation of the uncertainty from the linear spectral domain to the cepstral domain. This uncertainty is used by a decoder that exploits the variance associated with the enhanced cepstral features to improve robust speech recognition. Systematic evaluations on a subset of the Aurora4 task using the estimated uncertainty show substantial improvement over the baseline performance across various noise conditions.  相似文献   
120.
Containerless tube extrusion has been investigated with commerically pure titanium at room temperature and a strain rate of 0.07 s-1 using 20 conical dies of five different strains and four different angles with MoS2 lubricant. Theoretical punch pressures have been calculated using appropriate equations from slab analysis of the process and compared with experimentally determined punch pressures. It is found that there exists an optimum angle at which the punch pressure is the least at a given strain.  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