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   843篇
  免费   23篇
  国内免费   1篇
电工技术   5篇
综合类   3篇
化学工业   154篇
金属工艺   14篇
机械仪表   15篇
建筑科学   20篇
矿业工程   4篇
能源动力   3篇
轻工业   103篇
水利工程   19篇
石油天然气   2篇
无线电   53篇
一般工业技术   119篇
冶金工业   273篇
原子能技术   3篇
自动化技术   77篇
  2021年   8篇
  2020年   10篇
  2019年   15篇
  2018年   8篇
  2017年   10篇
  2016年   7篇
  2015年   9篇
  2014年   13篇
  2013年   50篇
  2012年   19篇
  2011年   17篇
  2010年   14篇
  2009年   20篇
  2008年   30篇
  2007年   28篇
  2006年   20篇
  2005年   11篇
  2004年   14篇
  2003年   22篇
  2002年   11篇
  2001年   13篇
  2000年   17篇
  1999年   18篇
  1998年   72篇
  1997年   42篇
  1996年   18篇
  1995年   24篇
  1994年   23篇
  1993年   31篇
  1992年   15篇
  1991年   7篇
  1990年   15篇
  1989年   13篇
  1988年   20篇
  1987年   16篇
  1986年   17篇
  1985年   16篇
  1984年   12篇
  1983年   10篇
  1982年   5篇
  1981年   12篇
  1979年   13篇
  1978年   7篇
  1977年   12篇
  1976年   8篇
  1975年   9篇
  1974年   10篇
  1973年   8篇
  1972年   9篇
  1967年   7篇
排序方式: 共有867条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
A program of research is summarized that represents the author's lifelong efforts to understand the adult life course of intellectual abilities. The Seattle Longitudinal Study has assessed mental abilities in more than 5,000 adults and has followed some for as long as 35 yrs. Integrative findings are provided on patterns and magnitudes of age changes, cohort differences, factor structure of mental abilities, antecedents for individual differences in aging trajectories, and interventions designed to remediate cognitive aging efforts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
5.
Using Web services, the authors have been able to increase the amount of data accessible through the Naval Research Laboratory’s Geospatial Information Database (GIDB) portal. They created a Web crawler for Web Mapping Services (WMS) that harvests and adds data to the portal index and a translator that provides access to non-WMS data through the WMS interface. The Integrated Web Services Broker, using traditional Web services standards, provides automated access to meteorological and oceanographic data.  相似文献   
6.
The rat magnocellular basal forebrain (MNBF) is homologous to the human nucleus basalis of Meynert, a structure implicated in the cholinergic hypothesis of cognitive impairment in Alzheimer's disease (AD). In the present study, 18 male Sprague-Dawley rats with kainic acid lesions in the MNBF were compared with 6 unoperated controls, 10 sham-operated controls, and 6 controls injected with kainic acid in the cortical area directly above the MNBF. MNBF lesions depleted choline acetyltransferase in cortex but not in striatum or hippocampus. Cortical dopamine levels were unchanged; serotonin levels were unchanged in hippocampus and parietal cortex but decreased in frontal cortex. Compared with controls, MNBF-lesioned Ss were impaired in 24-hr retention, but not acquisition, of a passive avoidance task with escapable footshock. The groups did not differ in mean number of daily avoidances on a barpress active avoidance task, although learning was slower in MNBF-lesioned Ss. In a serial spatial discrimination reversal test, MNBF-lesioned Ss performed significantly worse than controls. This model may be useful for studying the role of the cholinergic system in memory and possibly for developing treatment strategies to alleviate the cognitive dysfunction of AD. (63 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
7.
8.
9.
10.
The anisidine test, a measure of secondary oxidation products in glyceride oils, was applied to a number of soybean salad oils processed from sound and damaged soybeans. A highly significant correlation (−0.68) was found between the anisidine values of salad oils from sound soybeans and their flavor scores. Multiple correlations between flavor scores, anisidine, and peroxide values yielded a correlation of 0.81 and provided a method for predicting the initial flavor scores of sound soybean salad oils. Similar data for oils from damaged beans gave a highly significant, but lower, correlation (−0.65). Comparative studies indicated that sound crude oils usually contain lower levels of oxidation products than damaged crude. Oxidation in both sound and damaged crudes increased roughly in proportion to iron content. Reproducibility of the test and the effects of hydrogenation, accelerated storage, and fluorescent light on anisidine values were studied. Analysis of damaged oils before and after deodorization showed that little, if any, reduction of anisidine value occurred. Deodorization of sound oils, however, lowered anisidine values. In comparison with damaged oils, the anisidine values of sound oils were lower at comparable stages of processing. The poor quality of damaged soybean oil was substantiated by organoleptic evaluations. Flavor scores of oils given special processing treatments increased as anisidine values decreased.  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