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   4281篇
  免费   164篇
  国内免费   10篇
电工技术   47篇
综合类   5篇
化学工业   1037篇
金属工艺   79篇
机械仪表   89篇
建筑科学   305篇
矿业工程   6篇
能源动力   106篇
轻工业   406篇
水利工程   26篇
石油天然气   22篇
无线电   251篇
一般工业技术   703篇
冶金工业   784篇
原子能技术   58篇
自动化技术   531篇
  2022年   34篇
  2021年   49篇
  2020年   51篇
  2019年   56篇
  2018年   57篇
  2017年   76篇
  2016年   92篇
  2015年   58篇
  2014年   101篇
  2013年   298篇
  2012年   144篇
  2011年   223篇
  2010年   185篇
  2009年   161篇
  2008年   184篇
  2007年   188篇
  2006年   176篇
  2005年   145篇
  2004年   138篇
  2003年   126篇
  2002年   106篇
  2001年   87篇
  2000年   70篇
  1999年   66篇
  1998年   89篇
  1997年   78篇
  1996年   55篇
  1995年   59篇
  1994年   69篇
  1993年   57篇
  1992年   52篇
  1991年   50篇
  1990年   56篇
  1989年   65篇
  1988年   60篇
  1987年   36篇
  1986年   57篇
  1985年   58篇
  1984年   61篇
  1983年   51篇
  1982年   52篇
  1981年   55篇
  1980年   46篇
  1979年   57篇
  1978年   58篇
  1977年   46篇
  1976年   44篇
  1975年   32篇
  1974年   31篇
  1973年   37篇
排序方式: 共有4455条查询结果,搜索用时 15 毫秒
31.
In 3 eye-tracking experiments, the authors investigated the use of morphological information during pronoun resolution. Experiments 1 and 2 showed that disruption occurred when a preferred assignment was inconsistent with gender information. Experiment 2 ensured that this difficulty was not due to the introduction of a new discourse entity. Experiment 3 showed that disruption also occurred when number information was inconsistent with the preferred assignment. The results indicate that the use of morphological information is delayed until after the computation of coreference relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
32.
Performance variability across repeated task administrations may be an important indicator of age-related cognitive functioning. In the present investigation, the authors examined whether age differences and change in inconsistency were related to 6-year (3 occasion) cognitive change. Inconsistency scores were computed from 4 reaction time tasks performed by 446 older adults (54-89 years). Replicating previous cross-sectional results, greater inconsistency was observed for older participants even after controlling for differences in response speed. New longitudinal results demonstrated (a) associations between inconsistency at baseline measurement and 6-year change in cognitive performance; (b) longitudinal change in inconsistency; and (c) intraindividual covariation between 6-year change in inconsistency and 6-year change in level of cognitive function. These findings support the view that performance variability serves as a marker of cognitive aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
33.
Models for analyzing dependent competing risk data are presented. These models are designed to represent interactions of critical failure and maintenance mechanisms responsible for intercepting incipient and degraded failures, and they are fashioned such that the (constant) critical failure rate is identifiable from dependent competing risk data. Uncertainty bounds for the critical failure rate which take modeling uncertainty and statistical fluctuations into account are given.  相似文献   
34.
35.
MRI techniques were developed and employed for non-destructive and noninvasive study of seedcoat cracking in low moisture soybean kernels during heated air drying. Proton density image and transient moisture distribution profile of a single soybean kernel can be obtained using MRI. These MRI techniques proved to be particularly useful for the continuous observation of initiation and propagation of seedcoat cracking during the entire period of drying process without interruption.

The proton density images of soybean kernels showed that seedcoat cracking was initiated perpendicular to the long axis of the kernel near the hilum. The transient moisture distribution profiles in soybean kernels during drying indicate that moisture gradient developed during drying was higher in the seedcoat than in the cotyledon. Drying temperature and initial average moisture content were positively correlated with the soyhean seedcoat crackig. The location of the  相似文献   
36.
OBJECTIVE: There is substantial evidence demonstrating the aggravating effect of human immunodeficiency virus (HIV) infection on the progression of chronic hepatitis C virus (HCV) infection. There is however, little data on the affect of certain factors which could affect liver pathology findings in patients with concomitant HIV infection such as the duration of HIV infection or T-cell subpopulation counts. We examined pathology findings in patients with concomitant HIV and HCV infections to determine the impact of immunodepression. PATIENTS AND METHODS: We reviewed liver pathology data collected in patients with concomitant HIV and HCV infections grouping patients according to severity of the liver pathology: group 1 = cirrhosis or active hepatitis; group 2 = minimally active hepatitis or histologically normal liver. Transparietal liver biopsies were obtained for the work-up of viral hepatitis or because of long-term unexplained fever or suspected lymphoma. Epidemiological and biological data were obtained from medical files. The duration of the liver disease was estimated from the date of exposure to risk of immunodepression as determined by the peripheral CD4+ and CD8+ counts. All pathology specimens were read by two pathologists who established the Knodell score for each patient. RESULTS: Fifty patients were included: 23 were classed in group 1 and 28 in group 2. The Knodell score was significantly different between the two groups, 11 +/- 4 and 4 +/- 3 respectively (p < 0.0001). Disease duration was similar for the two groups: mean 8 years. Mean CD4+ count was significantly higher in group 1: 312/mm3 versus 110/mm3 for group 2 (p = 0.0057); as was the mean CD8+ count (758/mm3 versus 360/mm3, p = 0.0013). For the entire study population, there was a significantly negative correlation (p < 0.05) between the Knodell score and the CD4+ count (r = 0.31) and for the CD8+ count (r = 0.41). CONCLUSION: HCV-related liver pathology in patients co-infected with HIV depends on the level of immunodepression. CD8+ counts are better correlated with pathology findings than with CD4+ counts.  相似文献   
37.
38.
39.
40.
A modified CIECAM02 colour appearance model, named CIECAM02‐m2, is proposed to enable CIECAM02 to predict the simultaneous contrast effect. The structure of the CIECAM02‐m2 is a development from CIECAM02, and contains two different procedures for modifying the reference white; one is for lightness and the other is for hue. The model was tested using a data set accumulated in this study and the LUTCHI data. The CV values for three colour attributes between predictions and experimental data were used to evaluate the accuracy of the model. The low CV values obtained show the performance of the CIECAM02‐m2 model to predict the simultaneous contrast effect satisfactorily. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 121 – 129, 2007  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