全文获取类型
收费全文 | 1571篇 |
免费 | 7篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 26篇 |
综合类 | 18篇 |
化学工业 | 157篇 |
金属工艺 | 18篇 |
机械仪表 | 78篇 |
建筑科学 | 57篇 |
矿业工程 | 34篇 |
能源动力 | 5篇 |
轻工业 | 273篇 |
水利工程 | 17篇 |
石油天然气 | 46篇 |
武器工业 | 1篇 |
无线电 | 82篇 |
一般工业技术 | 635篇 |
冶金工业 | 23篇 |
原子能技术 | 1篇 |
自动化技术 | 115篇 |
出版年
2023年 | 3篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 10篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 7篇 |
2012年 | 163篇 |
2011年 | 183篇 |
2010年 | 51篇 |
2009年 | 22篇 |
2008年 | 161篇 |
2007年 | 143篇 |
2006年 | 125篇 |
2005年 | 122篇 |
2004年 | 65篇 |
2003年 | 72篇 |
2002年 | 66篇 |
2001年 | 45篇 |
2000年 | 43篇 |
1999年 | 25篇 |
1998年 | 18篇 |
1997年 | 23篇 |
1996年 | 16篇 |
1995年 | 16篇 |
1994年 | 25篇 |
1993年 | 21篇 |
1992年 | 19篇 |
1991年 | 12篇 |
1990年 | 16篇 |
1989年 | 20篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 8篇 |
1978年 | 2篇 |
1968年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
1954年 | 1篇 |
1948年 | 5篇 |
排序方式: 共有1586条查询结果,搜索用时 968 毫秒
1.
2.
3.
The clinical fertility tests, available in the market, fail to define the exact cause of male infertility in almost half of the cases and point toward a crucial need of developing better ways of infertility investigations. The protein biomarkers may help us toward better understanding of unknown cases of male infertility that, in turn, can guide us to find better therapeutic solutions. Many clinical attempts have been made to identify biomarkers of male infertility in sperm proteome but only few studies have targeted seminal plasma. Human seminal plasma is a rich source of proteins that are essentially required for development of sperm and successful fertilization. This viewpoint article highlights the importance of human seminal plasma proteome in reproductive physiology and suggests that differential proteomics integrated with functional analysis may help us in searching potential biomarkers of male infertility. 相似文献
4.
5.
6.
7.
8.
This paper presents a method of structuring the free space of a roving robot's environment into a set of overlapping convex regions ideally suited to path planning and navigation tasks. The structure of the free space environment is maintained as a hypergraph with each convex region represented by a hyperedge identifying the boundary walls of the region. A new methodology reveals the structure of free space and constructs the hypergraph representation through a directed search for a set of fundamental circits in an abstract graphical representation of the environment geometry. 相似文献
9.
We define and verify the utility of a pattern analysis procedure called sparse decomposition. This technique involves sequentially ``peeling' sparse subsets of patterns from a pattern set, where sparse subsets are sets of patterns which possess a certain degree of regularity or compactness as measured by a compactness measure c. If this is repeated until all patterns are deleted, then the sequence of decomposition ``layers' derived by this procedure provides a wealth of information from which inferences about the original pattern set may be made. A statistic P is derived from this information and is shown to be powerful in detecting clustering tendency for data in reasonably compact sampling windows. The test is applied to both synthetic and real data. 相似文献
10.
The 'found' experiment uses a natural change in conditions to investigate the possible effects of those conditions. In this case, the natural change was reduction in stiffness of Grand Prix suspensions between 1982 and 1983. The effects of this change on back pain in drivers were investigated and it was found that both the incidence and severity of back pain decreased significantly. Of the various possible sources of back pain, only the ride changed over the same period. This suggests that mechanical shock and vibration are a significant cause of driving related back pain. 相似文献