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   2319篇
  免费   65篇
电工技术   20篇
综合类   1篇
化学工业   377篇
金属工艺   24篇
机械仪表   30篇
建筑科学   53篇
矿业工程   2篇
能源动力   20篇
轻工业   74篇
水利工程   21篇
石油天然气   6篇
无线电   78篇
一般工业技术   164篇
冶金工业   1366篇
原子能技术   6篇
自动化技术   142篇
  2023年   9篇
  2022年   10篇
  2021年   23篇
  2020年   10篇
  2019年   17篇
  2018年   24篇
  2017年   24篇
  2016年   34篇
  2015年   14篇
  2014年   30篇
  2013年   45篇
  2012年   43篇
  2011年   62篇
  2010年   48篇
  2009年   60篇
  2008年   77篇
  2007年   51篇
  2006年   66篇
  2005年   53篇
  2004年   45篇
  2003年   32篇
  2002年   35篇
  2001年   41篇
  2000年   33篇
  1999年   52篇
  1998年   311篇
  1997年   203篇
  1996年   151篇
  1995年   86篇
  1994年   84篇
  1993年   91篇
  1992年   16篇
  1991年   29篇
  1990年   29篇
  1989年   34篇
  1988年   38篇
  1987年   30篇
  1986年   32篇
  1985年   26篇
  1984年   15篇
  1983年   14篇
  1982年   13篇
  1981年   23篇
  1980年   25篇
  1979年   9篇
  1978年   13篇
  1977年   37篇
  1976年   75篇
  1975年   20篇
  1974年   11篇
排序方式: 共有2384条查询结果,搜索用时 15 毫秒
11.
Patients with category-specific deficits have motivated a range of hypotheses about the structure of the conceptual system. One class of models claims that apparent category dissociations emerge from the internal structure of concepts rather than fractionation of the system into separate substores. This account claims that distinctive properties of concepts in the living domain are vulnerable because of their weak correlation with other features. Given the assumption that mutual activation among correlated properties produces faster activation in the normal system, the authors predicted a disadvantage for the distinctive features of living things for unimpaired adults. Results of a speeded feature verification study supported this prediction, as did a computational simulation in which networks mapped from orthography to semantics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
12.
The present study shows that extracellular adenosine triphosphate (ATP) has the capacity to mediate dose-dependent lysis of the monocytic leukemia cell line THP-1. The lysis, assessed by 51Cr release, was found to be selective for ATP, because adenosine diphosphate (ADP) or other nucleotides were less effective in their ability to lyse the cells. The amount of 51Cr released was particularly enhanced by the stimulation of the cells with 1,000 U/mL of interferon gamma (IFN-gamma) for 3 days, and the sensitivity was time and dose dependent. Analysis of the mechanism of lysis indicated that the fully ionized form, ATP4-, mediated the lysis, because the addition of cation chelators or the absence of the divalent cations, Ca2+ and Mg2+, in the culture medium of a 6-hour 51Cr release assay increased the percent specific lysis. Therefore, the ATP receptors on THP-1 cells were classified as P2Z purinoceptors. Moreover, it is shown here that the Ca2+/calmodulin complex plays a role in the regulation of the lysis by extracellular ATP of THP-1 cells, because antagonists of this complex, such as trifluoperazine or KN-62, were found to inhibit the ATP-mediated cell lysis.  相似文献   
13.
14.
Fenbendazole (Hoechst India Ltd.) was incorporated at 0.5 g/kg into urea molasses blocks made by two different processes. The proportion of the drug remaining in the blocks and the plasma concentrations of the parent compound and its metabolites were measured. Recovery of the drug in blocks made by the cold and the modified hot processes was 90% and 96%, respectively. The plasma metabolite profile revealed a plateau between days 4 and 6 of feeding in cattle and buffalo. However, the plasma concentrations of fenbendazole and its metabolites were low in buffalo compared to cattle.  相似文献   
15.
16.
17.
18.
South Africa’s Reconstruction and Development Programme set ambitious goals for providing basic services to all, including housing and electrification. More efficient use of energy has the potential to socially and politically support these goals, particularly when it is targeted at low-income communities lacking adequate energy services. This paper examines the economics of energy efficiency for the urban poor from the perspective of society, utilities and poor consumers, using five example programmes. While the five energy efficiency programmes generally have significant economic and environmental benefits from a social perspective, they may not be as attractive to utilities and consumers. Also examined are the policy options for overcoming the significant barriers to energy efficiency, and ways government can bridge the gap between what is good for society and what is good for the electricity industry.  相似文献   
19.
20.
This study evaluated the effectiveness of four posttreatment programs designed to enhance the long-term maintenance of weight loss. Mildly and moderately obese adults (N?=?123) were randomly assigned to one of the following five conditions: (a) behavior therapy only; (b) behavior therapy plus a posttreatment therapist-contact maintenance program; (c) behavior therapy plus posttreatment therapist contact plus a social influence maintenance program; (d) behavior therapy plus posttreatment therapist contact plus an aerobic exercise maintenance program; or (e) behavior therapy plus posttreatment therapist contact plus both the aerobic exercise and social influence maintenance programs. All posttreatment programs were conducted in 26 biweekly sessions during the year following behavioral treatment for obesity. At an 18-month follow-up evaluation, all four conditions that combined behavior therapy with a posttreatment maintenance program yielded significantly greater long-term weight losses than behavior therapy alone. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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