全文获取类型
收费全文 | 35342篇 |
免费 | 3689篇 |
国内免费 | 2494篇 |
专业分类
电工技术 | 2573篇 |
技术理论 | 8篇 |
综合类 | 5194篇 |
化学工业 | 2780篇 |
金属工艺 | 900篇 |
机械仪表 | 2311篇 |
建筑科学 | 3421篇 |
矿业工程 | 1259篇 |
能源动力 | 1254篇 |
轻工业 | 495篇 |
水利工程 | 1027篇 |
石油天然气 | 880篇 |
武器工业 | 597篇 |
无线电 | 3146篇 |
一般工业技术 | 4202篇 |
冶金工业 | 2118篇 |
原子能技术 | 326篇 |
自动化技术 | 9034篇 |
出版年
2024年 | 118篇 |
2023年 | 553篇 |
2022年 | 730篇 |
2021年 | 949篇 |
2020年 | 1092篇 |
2019年 | 993篇 |
2018年 | 1033篇 |
2017年 | 1185篇 |
2016年 | 1281篇 |
2015年 | 1311篇 |
2014年 | 2024篇 |
2013年 | 2474篇 |
2012年 | 2235篇 |
2011年 | 2565篇 |
2010年 | 2036篇 |
2009年 | 2144篇 |
2008年 | 2216篇 |
2007年 | 2332篇 |
2006年 | 2170篇 |
2005年 | 1883篇 |
2004年 | 1522篇 |
2003年 | 1269篇 |
2002年 | 1099篇 |
2001年 | 882篇 |
2000年 | 762篇 |
1999年 | 673篇 |
1998年 | 521篇 |
1997年 | 470篇 |
1996年 | 396篇 |
1995年 | 383篇 |
1994年 | 315篇 |
1993年 | 269篇 |
1992年 | 245篇 |
1991年 | 176篇 |
1990年 | 144篇 |
1989年 | 166篇 |
1988年 | 126篇 |
1987年 | 65篇 |
1986年 | 90篇 |
1985年 | 67篇 |
1984年 | 66篇 |
1983年 | 47篇 |
1982年 | 53篇 |
1981年 | 41篇 |
1980年 | 31篇 |
1979年 | 31篇 |
1978年 | 29篇 |
1977年 | 26篇 |
1964年 | 26篇 |
1955年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
No authorship indicated 《Canadian Metallurgical Quarterly》2003,58(11):931
Provides the biography of David W. Johnson and announces that he has won the Award for Distinguished Contributions of Applications of Psychology to Education and Training for programmatic research, comprehensive research reviews, and revision of theory over four decades of persistence that have provided the knowledge foundation for cooperative learning, constructive controversy, conflict resolution, and peer mediation training. A selected bibliography is also provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
72.
A model for preventive maintenance operations and forecasting 总被引:2,自引:1,他引:1
Equipment costs constitute the greatest majority of overall costs for semiconductor manufacturing. Therefore, maintaining
high equipment availability has been regarded as one of the major goals in the industry. The ability to forecast correctly
equipment preventive maintenance (PM) timing requirements not only can help optimizing equipment uptime but also minimizing
negative impacts on manufacturing production efficiency. This research used grey theory and evaluation diagnosis to construct
a PM forecasting model for prediction of PM timing of various machines. The results showed significant improvements of PM
timing predictions compared to the existing method based on experience and an alternative method proposed by Li and Chang
(Semiconductor Manufacturing Technology Workshop 2002: 10–11, pp. 275–277) for the same fab cases.
Received: June 2005 / Accepted: December 2005 相似文献
73.
74.
75.
ABSTRACT Postmortem structural changes in titin and nebulin filaments were investigated by incubating isolated myofibrils in a solution containing 0.1 mM calcium ions and various concentrations of a protease inhibitor. The inhibition curves showed 2 abnormal steps with increases in the concentration of leupeptin or calpastatin domain I. While the amounts of unchanged titin and nebulin were constant in the 1st step, the 2nd occurred at higher protease inhibitor concentrations. These facts indicated that excess amounts of leupeptin and calpastatin domain I caused deterioration in titin and nebulin properties, thus interfering with the binding of calcium ions. We concluded that the severance of titin and nebulin filaments in the 1st step were induced by calcium ions at 0.1 mM. 相似文献
76.
77.
78.
79.
Tams Insperger Gbor Stpn 《International journal for numerical methods in engineering》2004,61(1):117-141
An updated version of the semi‐discretization method is presented for periodic systems with a single discrete time delay. The delayed term is approximated as a weighted sum of two neighbouring discrete delayed state values and the transition matrix over a single period is determined. Stability charts are constructed for the damped and delayed Mathieu equation for different time‐period/time‐delay ratios. The convergence of the method is investigated by examples. Stability charts are constructed for 1 and 2 degree of freedom milling models. The codes of the algorithm are also attached in the appendix. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
80.
The theoretical-and-experimental investigation has been performed on the stability of smooth cylindrical shells of steel with a single local dent. All the shells manufactured using the same process were tested with the fulfillment of identical conditions for observations and measurements. Theoretical calculations were carried out by the mesh method with the use of the nonlinear theory of shells. A comparison of the experimental and theoretical values of the critical loads has been made. The theoretical-and-experimental approach proposed enables one to evaluate the quality of shells by studying local dents and other specific imperfections. 相似文献