全文获取类型
收费全文 | 4830篇 |
免费 | 160篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 86篇 |
综合类 | 6篇 |
化学工业 | 1038篇 |
金属工艺 | 98篇 |
机械仪表 | 80篇 |
建筑科学 | 306篇 |
矿业工程 | 19篇 |
能源动力 | 109篇 |
轻工业 | 682篇 |
水利工程 | 27篇 |
石油天然气 | 15篇 |
无线电 | 319篇 |
一般工业技术 | 675篇 |
冶金工业 | 866篇 |
原子能技术 | 49篇 |
自动化技术 | 619篇 |
出版年
2021年 | 55篇 |
2020年 | 41篇 |
2019年 | 60篇 |
2018年 | 60篇 |
2017年 | 45篇 |
2016年 | 96篇 |
2015年 | 83篇 |
2014年 | 149篇 |
2013年 | 224篇 |
2012年 | 187篇 |
2011年 | 189篇 |
2010年 | 169篇 |
2009年 | 193篇 |
2008年 | 195篇 |
2007年 | 187篇 |
2006年 | 185篇 |
2005年 | 159篇 |
2004年 | 141篇 |
2003年 | 130篇 |
2002年 | 77篇 |
2001年 | 78篇 |
2000年 | 92篇 |
1999年 | 83篇 |
1998年 | 170篇 |
1997年 | 109篇 |
1996年 | 82篇 |
1995年 | 64篇 |
1994年 | 62篇 |
1993年 | 67篇 |
1992年 | 54篇 |
1991年 | 44篇 |
1990年 | 62篇 |
1989年 | 63篇 |
1988年 | 50篇 |
1987年 | 62篇 |
1986年 | 40篇 |
1985年 | 63篇 |
1984年 | 62篇 |
1983年 | 49篇 |
1982年 | 44篇 |
1981年 | 55篇 |
1980年 | 64篇 |
1979年 | 53篇 |
1978年 | 47篇 |
1977年 | 66篇 |
1976年 | 64篇 |
1975年 | 34篇 |
1974年 | 46篇 |
1973年 | 32篇 |
1971年 | 33篇 |
排序方式: 共有4994条查询结果,搜索用时 484 毫秒
1.
Karim Gharbi Louise Matthews James Bron Ron Roberts Alan Tinch Michael Stear 《Journal of the Royal Society Interface》2015,12(110)
Sea lice threaten the welfare of farmed Atlantic salmon and the sustainability of fish farming across the world. Chemical treatments are the major method of control but drug resistance means that alternatives are urgently needed. Selective breeding can be a cheap and effective alternative. Here, we combine experimental trials and diagnostics to provide a practical protocol for quantifying resistance to sea lice. We then combined quantitative genetics with epidemiological modelling to make the first prediction of the response to selection, quantified in terms of reduced need for chemical treatments. We infected over 1400 young fish with Lepeophtheirus salmonis, the most important species in the Northern Hemisphere. Mechanisms of resistance were expressed early in infection. Consequently, the number of lice per fish and the ranking of families were very similar at 7 and 17 days post infection, providing a stable window for assessing susceptibility to infection. The heritability of lice numbers within this time window was moderately high at 0.3, confirming that selective breeding is viable. We combined an epidemiological model of sea lice infection and control on a salmon farm with genetic variation in susceptibility among individuals. We simulated 10 generations of selective breeding and examined the frequency of treatments needed to control infection. Our model predicted that substantially fewer chemical treatments are needed to control lice outbreaks in selected populations and chemical treatment could be unnecessary after 10 generations of selection. Selective breeding for sea lice resistance should reduce the impact of sea lice on fish health and thus substantially improve the sustainability of Atlantic salmon production. 相似文献
2.
This article proposes a model of the ways in which dyadic interactions between employees who occupy 1 of 4 archetypal social roles in organizations can lead to either episodic or institutionalized patterns of victimization. The model shows how the occurrence of victimization involving these 4 role types is influenced by organizational variables such as power differences, culture, and access to social capital. The model integrates behavioral and social structural antecedents of victimization to develop a relational perspective on the dynamics of harmful behavior in the workplace. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
A therapist's theoretical orientation is likely to influence every facet of the therapeutic process. We explore the relationship of therapeutic orientation and self-monitoring style. To test the hypothesis that high self-monitors would be more eclectic than low self-monitors, we surveyed 30 intake therapists at a child guidance center. Results supported the hypothesis; those frequently using more than one orientation had higher self-monitoring scores. Furthermore, self-monitoring correlated negatively with psychoanalytic endorsement, but in a positive direction with behavioral, systems and eclectic endorsements. Results are discussed in terms of training needs of those differing in self-monitoring style. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
Karl Rihaczek 《Datenschutz und Datensicherheit - DuD》2006,30(3):131-131
Ohne Zusammenfassung 相似文献
5.
当今,从事OC-48、OC-192技术的设计师在设计基于因特网协议(IP协议)的下一代系统时,因系统含有诸如ASIC、网络处理器(NP)、高速跟踪器等元件,以及分组SONET物理层(PoS-PHY)接口规范等的演变,而一直面临挑战。抖动和扭斜失真等现象的存在给诸如系统分组接口第4层(SPI-4)和通用交换接口(CSIX)等总线结构本已拥挤的时序容限,以及四元数据率静态RAM传送表访问时间带来极大混乱。再加上诸如低压差分信号(LVDS)、高速收发逻辑和短线串行终端逻辑等超低电压峰-峰信号技术的引入,使数据出错的可能性变得异常之高。而利用仿真技… 相似文献
6.
7.
SIMULATION STUDIES OF THE REMOVAL OF WATER FROM ETHANOL BY A CATALYTIC DISTILLATION PROCESS 总被引:1,自引:0,他引:1
Christina B. Dirk-Faitakis Karl T. Chuang 《Chemical Engineering Communications》2005,192(11):1541-1557
A new approach based on catalytic distillation (CD) technology was proposed to remove water from ethanol. Isobutylene was introduced to react with water in the CD column. The commercial software simulation tool Aspen Plus was used to investigate the effects of key design factors such as operating pressure and temperature, reactant ratios, reflux and distillate to feed ratios, number of separation and reaction stages, and feed and reaction zone location. It was found that the CD technology offers potential advantages of reduced energy consumption and reduced capital cost over traditional approaches for the removal of water from ethanol. 相似文献
8.
9.
Karl Micko 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1904,7(5):257-270
Ohne ZusammenfassungMitteilung aus der staatlichen Untersuchungsanstalt für Lebensmittel in Graz. 相似文献
10.