首页 | 官方网站   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   4725篇
  免费   150篇
  国内免费   10篇
工业技术   4885篇
  2021年   60篇
  2020年   52篇
  2019年   60篇
  2018年   70篇
  2017年   57篇
  2016年   98篇
  2015年   84篇
  2014年   118篇
  2013年   222篇
  2012年   179篇
  2011年   269篇
  2010年   195篇
  2009年   173篇
  2008年   203篇
  2007年   200篇
  2006年   145篇
  2005年   169篇
  2004年   140篇
  2003年   113篇
  2002年   93篇
  2001年   91篇
  2000年   98篇
  1999年   103篇
  1998年   135篇
  1997年   109篇
  1996年   91篇
  1995年   90篇
  1994年   80篇
  1993年   85篇
  1992年   74篇
  1991年   54篇
  1990年   79篇
  1989年   50篇
  1988年   53篇
  1987年   58篇
  1986年   45篇
  1985年   66篇
  1984年   58篇
  1983年   49篇
  1982年   55篇
  1981年   50篇
  1980年   34篇
  1979年   47篇
  1978年   47篇
  1977年   65篇
  1976年   46篇
  1975年   39篇
  1974年   57篇
  1972年   39篇
  1970年   36篇
排序方式: 共有4885条查询结果,搜索用时 15 毫秒
31.
Works of adhesion WSL between aqueous solutions with pH values in the range from 1 to 14 and carbon fibers from different sources, which were additionally treated in an inert atmosphere or in oxygen, were measured by use of a microbalance. These works of adhesion WSL were found to show distinct stepwise dependencies on the pH value. The works of adhesion WSL are attributed to dispersion interactions WSL1 and various acid-base interactions wslab—in the latter case between the acidic and basic surface groups of carbon and the various basic and acidic aqueous solutions.  相似文献   
32.
33.
34.
The proposed new color-difference formula of CIE TC 129, which is a modified version of CIELAB, was tested with a recently published data set of textile pass/fail judgments. Goodness of fit is improved, if the parameter of lightness is set near 2, and if, additionally, a weight function for lightness is defined that reduces the weight of a lightness difference with lightness level in relation to chroma or hue scaling. © 1994 John Wiley & Sons, Inc.  相似文献   
35.
改进的DMT/PTA工艺技术是由苏尔寿化工有限公司和H&G Hegmanns公司联合开发的。该技术对Witten-Katzschmann工艺进行了大量改进,并结合了苏尔寿公司的环境友好熔融结晶技术。改进的工艺包括:氧化反应部分(有效回收了副产品和能量);粗酯和副产品蒸馏;采用熔融结晶技术精制DMT。  相似文献   
36.
[Correction Notice: An erratum for this article was reported in Vol 29(6) of Journal of Experimental Psychology: Learning, Memory, and Cognition (see record 2007-16865-001). On page 684, Table 4, all correlations should have been identified as having a pp then q") as indicating a high conditional probability P(q|p). Participants estimated the probability that a given conditional is true (Experiments 1A, 1B, and 3) or judged whether a conditional was true or false (Experiments 2 and 4) given information about the frequencies of the relevant truth table cases. Judgments were strongly influenced by the ratio of pq to p?q cases, supporting the conditional probability account. In Experiments 1A, 1B, and 3, judgments were also affected by the frequency of pq cases, consistent with a version of mental model theory. Experiments 3 and 4 extended the results to thematic conditionals and showed that the pragmatic utility associated with believing a statement also affected the degree of belief in conditionals but not in logically equivalent quantified statements. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
37.
38.
In connection with the analysis and the development of failure concepts in fracture mechanics for quasistatic loaded components and elastic-plastic behaviour of the material, tests are also carried out with welded and/or complex shaped specimens or structures. Thereby the difficulty arises of generating reproducible flaws in the form of fatigue precracks in definite positions in the components, respectively in the welded joint. It is reported exemplarily about experiments on different CT25 and CCT specimens and on a pressure vessel which contained a fatigue pre-crack, a 0.2 mm saw cut or notches with notch root radius ≤ ≥ 0.1 mm as flaws. The comparison of the results with regard to J-integral at initiation of stable crack, Ji, and JR curves shows that under certain conditions the 0.2 mm saw cut (notch root radius ≤ ≤ 0.02 mm) is a useful alternative, if reproducible generation of a fatigue pre-crack will not be successful or too expensive. The tests were carried out on StE 460 and on a welded joint of this steel at 25 ± 2°C.  相似文献   
39.
40.
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-23

京公网安备 11010802026262号