全文获取类型
收费全文 | 413191篇 |
免费 | 4453篇 |
国内免费 | 1034篇 |
专业分类
电工技术 | 7863篇 |
综合类 | 376篇 |
化学工业 | 61975篇 |
金属工艺 | 15824篇 |
机械仪表 | 12097篇 |
建筑科学 | 8987篇 |
矿业工程 | 2047篇 |
能源动力 | 9326篇 |
轻工业 | 36428篇 |
水利工程 | 3941篇 |
石油天然气 | 7333篇 |
武器工业 | 38篇 |
无线电 | 48864篇 |
一般工业技术 | 77222篇 |
冶金工业 | 86195篇 |
原子能技术 | 8886篇 |
自动化技术 | 31276篇 |
出版年
2021年 | 3133篇 |
2019年 | 3072篇 |
2018年 | 5240篇 |
2017年 | 5159篇 |
2016年 | 5471篇 |
2015年 | 3526篇 |
2014年 | 6067篇 |
2013年 | 17137篇 |
2012年 | 9919篇 |
2011年 | 13514篇 |
2010年 | 10819篇 |
2009年 | 12237篇 |
2008年 | 12869篇 |
2007年 | 13052篇 |
2006年 | 11701篇 |
2005年 | 10635篇 |
2004年 | 10401篇 |
2003年 | 10038篇 |
2002年 | 9924篇 |
2001年 | 10108篇 |
2000年 | 9620篇 |
1999年 | 10094篇 |
1998年 | 26613篇 |
1997年 | 18179篇 |
1996年 | 13950篇 |
1995年 | 10474篇 |
1994年 | 9191篇 |
1993年 | 9136篇 |
1992年 | 6624篇 |
1991年 | 6246篇 |
1990年 | 6371篇 |
1989年 | 6135篇 |
1988年 | 5731篇 |
1987年 | 4832篇 |
1986年 | 4924篇 |
1985年 | 5684篇 |
1984年 | 5223篇 |
1983年 | 4666篇 |
1982年 | 4385篇 |
1981年 | 4574篇 |
1980年 | 4268篇 |
1979年 | 4051篇 |
1978年 | 4097篇 |
1977年 | 4704篇 |
1976年 | 6226篇 |
1975年 | 3578篇 |
1974年 | 3407篇 |
1973年 | 3509篇 |
1972年 | 2926篇 |
1971年 | 2649篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
172.
173.
In the editorial by J.C. Bezdek (ibid., p.1), an example is presented to demonstrate differences between fuzzy membership and probability. The authors argue that probability can be used in a way much more closely analogous to this use of fuzzy membership, weakening the argument for the latter 相似文献
174.
Wesley W. Chu Ph.D. Ion T. leong Ph.D. Ricky K. Taira Ph.D. 《The VLDB Journal The International Journal on Very Large Data Bases》1994,3(4):445-477
We introduce a semantic data model to capture the hierarchical, spatial, temporal, and evolutionary semantics of images in pictorial databases. This model mimics the user's conceptual view of the image content, providing the framework and guidelines for preprocessing to extract image features. Based on the model constructs, a spatial evolutionary query language (SEQL), which provides direct image object manipulation capabilities, is presented. With semantic information captured in the model, spatial evolutionary queries are answered efficiently. Using an object-oriented platform, a prototype medical-image management system was implemented at UCLA to demonstrate the feasibility of the proposed approach. 相似文献
175.
Variations in lipid profile and incidence of vascular events were evaluated. Group 1 had a 29.3% reduction of total and a 38.3% reduction of LDL cholesterol as against reductions of 9% and 9.6% respectively in group 2. No significant difference was observed between the two groups as far as the vascular events considered were concerned. Pravastatin is an effective and safe drug. The lack of influence on the evolution of vascular disease would appear to be correlated to the small number of subjects studied and the short follow-up. 相似文献
176.
Family nursing, always a component of nursing, has been recently receiving increased attention through publications, educational programs, clinical practice settings and family nursing research. Nurses are in the best position to assist families experiencing the illness of a loved one, but often lack the skills and confidence necessary to assist with the psychosocial needs. The purpose of this paper is to describe the development and implementation of a family nursing program within a large, tertiary care facility. The program's evaluation is ongoing but early outcomes indicate that day-to-day nursing practice has been positively influenced and improved job satisfaction may result. 相似文献
177.
178.
179.
F. Cioffi E. M. Cohen Richard Badick 《Drug development and industrial pharmacy》1993,19(14):1741-1746
Carstensen and Rhodes1 have suggested that when, in stability programs, assays cannot be performed immediately after the protocol-designated storage time, then freezing them until such a time when assays can be performed would be a reasonable manner to retain the protocol schedule. They caution, however, that such a procedure may not be valid for dissolution data. The article to follow deals with real-time data showing that such a process is feasible for Nalidixic Acid tablets (and presumably for other tablets as well), and that, furthermore, the dissolution pattern would seem to be “frozen” as well. 相似文献
180.