全文获取类型
收费全文 | 843篇 |
免费 | 23篇 |
国内免费 | 1篇 |
专业分类
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 |
出版年
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.
Sample J.T. Ladner R. Shulman L. Ioup E. Petry F. Warner E. Shaw K. McCreedy F.P. 《Internet Computing, IEEE》2006,10(5):53-60
Using Web services, the authors have been able to increase the amount of data accessible through the Naval Research Laboratorys 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.
Lerer Barbara; Warner John; Friedman Eitan; Vincent George; Gamzu Elkan 《Canadian Metallurgical Quarterly》1985,99(4):661
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.
DO Warner 《Canadian Metallurgical Quarterly》1998,88(6):1433-1434
9.
10.
G. R. List C. D. Evans W. F. Kwolek K. Warner B. K. Boundy J. C. Cowan 《Journal of the American Oil Chemists' Society》1974,51(2):17-21
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