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   1773篇
  免费   279篇
  国内免费   175篇
电工技术   54篇
综合类   150篇
化学工业   140篇
金属工艺   18篇
机械仪表   53篇
建筑科学   143篇
矿业工程   16篇
能源动力   21篇
轻工业   272篇
水利工程   42篇
石油天然气   8篇
武器工业   11篇
无线电   90篇
一般工业技术   169篇
冶金工业   201篇
原子能技术   1篇
自动化技术   838篇
  2024年   9篇
  2023年   30篇
  2022年   79篇
  2021年   114篇
  2020年   111篇
  2019年   95篇
  2018年   91篇
  2017年   90篇
  2016年   108篇
  2015年   93篇
  2014年   133篇
  2013年   113篇
  2012年   115篇
  2011年   99篇
  2010年   95篇
  2009年   97篇
  2008年   103篇
  2007年   103篇
  2006年   79篇
  2005年   56篇
  2004年   66篇
  2003年   42篇
  2002年   54篇
  2001年   36篇
  2000年   24篇
  1999年   16篇
  1998年   23篇
  1997年   12篇
  1996年   14篇
  1995年   10篇
  1994年   12篇
  1993年   11篇
  1992年   11篇
  1991年   4篇
  1990年   6篇
  1989年   4篇
  1988年   5篇
  1986年   5篇
  1985年   5篇
  1983年   3篇
  1982年   4篇
  1981年   3篇
  1966年   3篇
  1965年   3篇
  1964年   3篇
  1963年   2篇
  1959年   4篇
  1958年   5篇
  1956年   2篇
  1955年   6篇
排序方式: 共有2227条查询结果,搜索用时 15 毫秒
11.
The authors examined students' understanding of hypotheses as beliefs that can be empirically verified. Thirty second graders and 30 sixth graders considered cases of disagreement about foods and colors that reflected either alternative hypotheses or different preferences. Their task was to decide whether the validity of each expressed belief could be determined and to justify their decision. Younger students considered both hypotheses and preferences as empirically verifiable, whereas older students were better able to recognize in some cases that preferences are legitimately variable. This lack of distinction may reflect limited metaconceptual ability or a deterministic epistemological view, both of which might interfere with the understanding of the hypothesis-testing process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
12.
Almond preferences were produced by giving rats a mixture of almond and sucrose (Experiments 1-4) or saccharin (Experiment 4). A subsequent extinction procedure consisted of either repeated 2-bottle almond versus water tests (Experiment 1) or repeated exposure to almond alone (Experiments 2-4). The main independent variable was whether access to food following a session was given immediately, 30 min later, or 120 min later. No effect of extinction was found in any experiment. An important finding was that varying the delay until food access had no detectable effect. It was concluded that inadvertent flavor-food associations do not maintain preference for the flavor under extinction conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
13.
We introduce Kripke semantics for modal substructural logics, and provethe completeness theorems with respect to the semantics. Thecompleteness theorems are proved using an extended Ishihara's method ofcanonical model construction (Ishihara, 2000). The framework presentedcan deal with a broad range of modal substructural logics, including afragment of modal intuitionistic linear logic, and modal versions ofCorsi's logics, Visser's logic, Méndez's logics and relevant logics.  相似文献   
14.
沈晓刚 《矿业工程》2003,1(4):58-60
引进采掘设备是个复杂的工作,它不但牵涉到采矿能力的提高,同时也要考虑相应工艺的配套和设备管理所带来的问题,因此,引进采掘设备必须系统研究。  相似文献   
15.
The relative liking or disliking that beer drinkers have for characteristics generally regarded as off‐flavours by brewers, namely lightstruck and stale, has been explored in a consumer trial where products are presented branded and unbranded. Drinkers display a significant preference for fresh over lightstruck product, irrespective of branding. By contrast, drinkers seemed to be less clear about their liking or otherwise for stale character, although in this case they clearly prefer the branded product over the unbranded product when the beers are fresh and vice‐versa when the beer is aged. A stale version of a beer that consumers are familiar with fails to meet expectations for that product. Significant numbers of drinkers do declare a liking for lightstruck and aged character.  相似文献   
16.
The conditioned cue preference (CCP) task was used to study the information required to discriminate between spatial locations defined by adjacent arms of an 8-arm radial maze. Normal rats learned the discrimination after 3 unreinforced preexposure (PE) sessions and 4 food paired-unpaired training trials. Fimbria-fornix lesions made before, but not after, PE, and hippocampus lesions made at either time, blocked the discrimination, suggesting that the 2 structures processed different information. Lateral amygdala lesions made before PE facilitated the discrimination. This amygdala-mediated interference with the discrimination was the result of a conditioned approach response that did not discriminate between the 2 arm locations. A hippocampus/fimbria-fornix system and an amygdala system process different information about the same learning situation simultaneously and in parallel. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
17.
A feature of the empirical literature in colour psychology is that little attention has been given to how people in real settings engage in colour selection. Surprisingly, with rare exceptions, we know almost nothing about this. Besides its theoretical significance within psychology, this question has practical implications for industries where colour choice is important. A study is reported into that most ubiquitous of activities, selecting a paint colour for the home. This used a retrospective method supported by qualitative data analysis (NVivo) in which participants described their process of colour selection. The results indicate a process that is far from uniform, but one that consists of two essential stages. The first involves arriving at what we refer to as an affective specification of the qualities sought. Once constructed, this leads to the second stage of matching colour attributes to that specification. Selecting a wall colour emerges as a surprisingly complex process, and one that corresponds more closely to a search than to a simple affective choice. A parallel is drawn with decision research, particularly the field of naturalistic decision‐making. From participants' reports, colour selection also emerges as a process that women appear to understand better than men. © 2007 Wiley Periodicals, Inc. Col Res Appl, 33, 55–60, 2008  相似文献   
18.
S.R. Jaeger    C.M. Lund    K. Lau    F.R. Harker 《Journal of food science》2003,68(3):1108-1117
Preference mapping with 10 pears identified 3 segments among New Zealand consumers. While 1 segment preferred ripe European cultivars, another rejected only the seedling with strong off‐flavors. A 3rd segment combined the 2 former segments, but also rejected 2 hybrid samples. Survey responses to the question “To me, the ideal pear is ?” from a 2nd consumer sample confirmed the general preference for juicy and sweet pears, the key characteristics of ripeness. A separate appearance evaluation revealed 4 segments based on color and shape. Combining information from several sources resulted in suggestions for new breeding directions for pears, while highlighting the importance of appearance and the need for more extensive measurements.  相似文献   
19.
This paper presentes a novel resolution method,T-resolution,based on the first order temporal logic.The primary claim of this method is its soundness and completeness.For this purpose,we construct the corresponding semantic trees and extend Herbrand‘s Theorem.  相似文献   
20.
对笔者提出的连拱坝动力特性计算的子结构交叉综合法的正确性进行了证明.利用证明子结构子模态向量组成的线性空间是完备的基础上,说明当交叉子结构中所取的截尾模态趋向于完备时,其结果等同于整体计算,并表明近似计算将收敛于正确的结果.  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