全文获取类型
收费全文 | 21079篇 |
免费 | 1381篇 |
国内免费 | 915篇 |
专业分类
电工技术 | 774篇 |
技术理论 | 1篇 |
综合类 | 1978篇 |
化学工业 | 705篇 |
金属工艺 | 760篇 |
机械仪表 | 1708篇 |
建筑科学 | 1313篇 |
矿业工程 | 565篇 |
能源动力 | 326篇 |
轻工业 | 348篇 |
水利工程 | 243篇 |
石油天然气 | 563篇 |
武器工业 | 152篇 |
无线电 | 1550篇 |
一般工业技术 | 950篇 |
冶金工业 | 921篇 |
原子能技术 | 319篇 |
自动化技术 | 10199篇 |
出版年
2024年 | 12篇 |
2023年 | 83篇 |
2022年 | 129篇 |
2021年 | 170篇 |
2020年 | 183篇 |
2019年 | 167篇 |
2018年 | 188篇 |
2017年 | 369篇 |
2016年 | 412篇 |
2015年 | 453篇 |
2014年 | 1095篇 |
2013年 | 827篇 |
2012年 | 1215篇 |
2011年 | 1735篇 |
2010年 | 1289篇 |
2009年 | 1088篇 |
2008年 | 1173篇 |
2007年 | 1341篇 |
2006年 | 1172篇 |
2005年 | 1079篇 |
2004年 | 963篇 |
2003年 | 1050篇 |
2002年 | 863篇 |
2001年 | 780篇 |
2000年 | 731篇 |
1999年 | 704篇 |
1998年 | 710篇 |
1997年 | 593篇 |
1996年 | 492篇 |
1995年 | 408篇 |
1994年 | 275篇 |
1993年 | 277篇 |
1992年 | 215篇 |
1991年 | 179篇 |
1990年 | 113篇 |
1989年 | 110篇 |
1988年 | 120篇 |
1987年 | 61篇 |
1986年 | 74篇 |
1985年 | 94篇 |
1984年 | 70篇 |
1983年 | 45篇 |
1982年 | 28篇 |
1981年 | 38篇 |
1980年 | 21篇 |
1979年 | 30篇 |
1977年 | 12篇 |
1976年 | 16篇 |
1975年 | 12篇 |
1974年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 99 毫秒
31.
B737机务CBT系统建设方案的探讨 总被引:3,自引:0,他引:3
张旭 《上海工程技术大学学报》2004,18(4):375-378
通过对AICC制订的CBT课件开发规范的探讨,阐述了CBT的基本概念和波音737飞机机务CBT的开发制作过程,以及利用Authorware开发软件制作多媒体课件的技术难点。 相似文献
32.
针对实时CSCW系统中的迟加入问题,提出了一个改进的多“迟加入Server”算法。该算法能够有效的解决让“迟加入Client”可靠加入到协同工作的问题。通过实例验证了该算法的有效性,为进行更高效的协同工作提供了支持。 相似文献
33.
Garth Isaak 《Information Processing Letters》2004,92(3):107-111
Given a tournament with an acyclic tournament as a feedback arc set we give necessary and sufficient conditions for this feedback arc set to have minimum size. 相似文献
34.
The changes in surface composition of metallic alloys caused by segregation can be very efficiently studied by low-energy ion scattering (LEIS) due to the specific surface sensitivity of this technique. Investigations of single-crystal surfaces of ordered alloys are of particular interest because they provide the possibility to investigate the interplay between segregation effects and the order-disorder phase transition when passing through the transition temperature. Exemplifying these effects for bimetallic alloys we consider in particular the CuAu-system.For the quantitative interpretation of energy and angle resolved LEIS intensity distributions we compare experimental results with those from numerical simulations using the MARLOWE code which we extended with a detailed trajectory analysis. This allows us to apply various discrimination criteria, such as number of collisions, distance of closest approach, identification of the scattering crystal layer, total path length, etc. On this basis structural effects, ion survival probabilities and the influence of thermal vibrations can be studied.We demonstrate this potential by using CuAu(1 0 0) as a special example. The scattering potential parameters were calibrated with elemental single crystals of known structures and the anisotropic Debye temperatures taken from the literature showed good agreement, neutralization was of minor importance in this case. Our procedure could be successfully used for the quantitative analysis of the composition of the first and second layer as a function of temperature. These results are in good agreement with theoretical predictions. 相似文献
35.
36.
Depression is a widespread disorder with devastating individual and societal consequences. Although a great deal of research and theory has focused on treatment of acute episodes, progress needs to be made in preventing the emergence of first episodes of the disorder. There has been considerable advancement in understanding psychological vulnerability factors associated with this mood disorder, especially on the basis of cognitive behavioural models and research findings based on this theoretical model. In this paper we review the concept of cognitive vulnerability, with a particular focus on what this body of research work suggests clinically for the prevention of depression. We outline, based on this science, what the effective ingredients of a prevention program could be. We also discuss some of the pragmatic aspects of developing an effective prevention program for depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
37.
Mark Taylor John Miles Dino Bouchlaghem Chimay Anumba 《Canadian Metallurgical Quarterly》2007,21(1):59-62
IT systems for engineers are becoming more numerous and complex and will further proliferate in the future. It is infeasible to expect users to be trained to work with a plethora of systems, especially as many of them will only see occasional use. Therefore, in the near future, systems will need user interfaces that allow intuitive access and usage. This paper examines a new style of user interface based on virtual reality. 相似文献
38.
A new spreadsheet-cell-object-oriented algorithm for the first-order reliability method is proposed and illustrated for cases with correlated nonnormals and explicit and implicit performance functions. The new approach differs from the writers earlier algorithm by obviating the need for computations of equivalent normal means and equivalent normal standard deviations. It obtains the solution faster and is more efficient, robust, and succinct. Other advantages include ease of initialization prior to constrained optimization, ease of randomization of initial values for checking robustness, and fewer required optimization constraints during spreadsheet-automated search for the design point. Two cases with implicit performance functions, namely an asymmetrically loaded beam on Winkler medium and a strut with complex supports are analyzed using the new approach and discussed. Comparisons are also made between the proposed approach and that based on Rosenblatt transformation. 相似文献
39.
Prolog逻辑程序设计语言具有不同于传统程序设计语言的特点.本文根据测试Prolog程序的实践,提出了一系列为Prolog程序生成测试用例的准则.按这些准则测试实际程序效果良好.这是在逻辑程序测试新领域迈出的一步. 相似文献
40.