全文获取类型
收费全文 | 10411篇 |
免费 | 1565篇 |
国内免费 | 1013篇 |
专业分类
电工技术 | 1205篇 |
综合类 | 1176篇 |
化学工业 | 363篇 |
金属工艺 | 207篇 |
机械仪表 | 612篇 |
建筑科学 | 624篇 |
矿业工程 | 601篇 |
能源动力 | 193篇 |
轻工业 | 158篇 |
水利工程 | 252篇 |
石油天然气 | 297篇 |
武器工业 | 219篇 |
无线电 | 1485篇 |
一般工业技术 | 687篇 |
冶金工业 | 800篇 |
原子能技术 | 55篇 |
自动化技术 | 4055篇 |
出版年
2024年 | 40篇 |
2023年 | 121篇 |
2022年 | 275篇 |
2021年 | 324篇 |
2020年 | 370篇 |
2019年 | 289篇 |
2018年 | 328篇 |
2017年 | 398篇 |
2016年 | 427篇 |
2015年 | 555篇 |
2014年 | 729篇 |
2013年 | 704篇 |
2012年 | 868篇 |
2011年 | 903篇 |
2010年 | 722篇 |
2009年 | 691篇 |
2008年 | 754篇 |
2007年 | 831篇 |
2006年 | 632篇 |
2005年 | 537篇 |
2004年 | 413篇 |
2003年 | 413篇 |
2002年 | 348篇 |
2001年 | 257篇 |
2000年 | 170篇 |
1999年 | 147篇 |
1998年 | 115篇 |
1997年 | 102篇 |
1996年 | 63篇 |
1995年 | 66篇 |
1994年 | 60篇 |
1993年 | 52篇 |
1992年 | 33篇 |
1991年 | 20篇 |
1990年 | 17篇 |
1989年 | 19篇 |
1988年 | 15篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1965年 | 11篇 |
1964年 | 10篇 |
1963年 | 14篇 |
1961年 | 15篇 |
1960年 | 15篇 |
1959年 | 9篇 |
1957年 | 8篇 |
1956年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
河南省电力公司远程教育平台,作为一个省内电力系统职工的再教育、技术培训、技能培训中心,访问量大,安全要求高,我们在软件设计时充分考虑到系统的安全性。 相似文献
45.
46.
A separation distance between adjacent buildings is provided to reduce the risk of pounding of adjacent buildings under seismic excitations. It should be recognized that the evaluation of the critical separation distance is a one-sided barrier crossing problem while the problem of structural design under seismic excitations is a two-sided crossing problem. A procedure for assessing the required separation distance with or without considering possible uncertainty in structural properties was presented based on the reliability methods and random vibration theory. The procedure was used to carry out parametric analyses. It is shown that use of the complete quadratic combination (CQC) rule with the modal responses employed for designing structures may over- or underestimate the critical separation distance, depending on the damping ratios and the closeness of the natural vibration periods of adjacent buildings. This is due to not only one-sided versus two-sided crossing problem but also the approximation in the CQC rule. Further, the effect of the uncertainty in structural properties on the estimated separation is investigated. The results indicate that this uncertainty tends to increase the required critical separation distance. 相似文献
47.
管线油电损耗的灰色模型及预测 总被引:11,自引:2,他引:9
对于管道运输来说,影响输油成本变化的因素有很多,但是对总成本影响最大的是油电损耗费用。由于来自现场的输量和相关参数样本数据不足,只知道连续几年的流量、油电损耗,要预测将来每年的油电损耗,经典经济数学不能满足这样的研究。然而灰色系统理论要求的研究样本较少,只要知道连续几年的流量、油电损耗,就能预测将来每年的油电损耗,估算其输油成本,且模型精度较高。利用灰色系统理论,以输油管线每年的输量、相应的电耗和油耗为时间序列,建立了三元素非等间距GM(1,1)模型,该模型为预测管线年输油成本提供了可靠的依据。 相似文献
48.
49.
Watson Jeanne C.; Gordon Laurel B.; Stermac Lana; Kalogerakos Freda; Steckley Patricia 《Canadian Metallurgical Quarterly》2003,71(4):773
This study compared process-experiential and cognitive-behavioral psychotherapy in the treatment of major depression in a researcher allegiance-balanced randomized clinical trial. Sixty-six clients participated in weekly sessions of psychotherapy for 16 weeks. Clients' level of depression, self-esteem, general symptom distress, and dysfunctional attitudes significantly improved in both therapy groups. Clients in both groups showed significantly lower levels of reactive and suppressive coping strategies and higher reflective coping at the end of treatment. Although outcomes were generally equivalent for the 2 treatments, there was a significantly greater decrease in clients' self-reports of their interpersonal problems in process-experiential than cognitive-behavioral therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
50.
History is bunk, declared Henry Ford; he wanted to sell new cars every year. For psychoanalysis history is not bunk; it is its very heart and guts. Like an individual or a nation, psychoanalysis lives its history and rediscovers it in every generation. Psychoanalytic pioneers, authors of new rallying cries and new theories, seem to think otherwise: History of psychoanalysis begins with them. The author suggests a different approach: to see the new as a historical continuity of the old. The advocates of the relational approach in psychoanalysis will be surprised to hear that Freud was a Sullivanian, even though--like the proverbial M. Jourdain who never heard the word prose--he never heard of the word interpersonal. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献