全文获取类型
收费全文 | 23006篇 |
免费 | 2759篇 |
国内免费 | 1923篇 |
专业分类
电工技术 | 870篇 |
技术理论 | 1篇 |
综合类 | 2258篇 |
化学工业 | 4067篇 |
金属工艺 | 781篇 |
机械仪表 | 795篇 |
建筑科学 | 2272篇 |
矿业工程 | 473篇 |
能源动力 | 638篇 |
轻工业 | 2338篇 |
水利工程 | 798篇 |
石油天然气 | 1242篇 |
武器工业 | 544篇 |
无线电 | 1744篇 |
一般工业技术 | 2951篇 |
冶金工业 | 1491篇 |
原子能技术 | 320篇 |
自动化技术 | 4105篇 |
出版年
2024年 | 161篇 |
2023年 | 566篇 |
2022年 | 993篇 |
2021年 | 1100篇 |
2020年 | 1062篇 |
2019年 | 855篇 |
2018年 | 795篇 |
2017年 | 940篇 |
2016年 | 980篇 |
2015年 | 950篇 |
2014年 | 1414篇 |
2013年 | 1543篇 |
2012年 | 1562篇 |
2011年 | 1589篇 |
2010年 | 1183篇 |
2009年 | 1257篇 |
2008年 | 1193篇 |
2007年 | 1389篇 |
2006年 | 1195篇 |
2005年 | 1108篇 |
2004年 | 881篇 |
2003年 | 785篇 |
2002年 | 710篇 |
2001年 | 564篇 |
2000年 | 454篇 |
1999年 | 391篇 |
1998年 | 288篇 |
1997年 | 257篇 |
1996年 | 205篇 |
1995年 | 219篇 |
1994年 | 156篇 |
1993年 | 140篇 |
1992年 | 130篇 |
1991年 | 100篇 |
1990年 | 100篇 |
1989年 | 87篇 |
1988年 | 67篇 |
1987年 | 38篇 |
1986年 | 23篇 |
1985年 | 37篇 |
1984年 | 35篇 |
1983年 | 33篇 |
1982年 | 28篇 |
1980年 | 13篇 |
1979年 | 13篇 |
1964年 | 7篇 |
1963年 | 7篇 |
1959年 | 8篇 |
1957年 | 7篇 |
1955年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 22 毫秒
61.
The object of study is a stationary Gaussian white noise excited multi-degree-of-freedom (MDOF) linear elastic, ideal plastic, linearly damped, statically determinate oscillator with several potential elements of ideal plastic yielding. Specifically the study is exemplified for a plane multistory shear frame with rigid traverses where all the connecting columns except the columns in one or more of the bottom floors have finite symmetrical yield limits. The white noise excitation acts on the mass of the first floor making the movement of the elastic bottom floors simulate a ground motion that interacts with the structure above the bottom floors. The method of study is so-called Slepian model simulation and is in principle the same for other statically determinate MDOF elasto-plastic oscillators of the considered type. The method is fast as compared to direct simulation and provides results that give good insight in the behavior of the plastic displacement response process. 相似文献
62.
论大学生体育参与动机的培养 总被引:1,自引:0,他引:1
施亚菊 《宁波工程学院学报》2002,14(1):69-70,79
大学生具有良好的参与动机是实现体育教学目标的一个重要前提条件。本文通过对体育参与动机内涵及影响体育参与动机的心理因素的分析,提出了大学体育教学中如何培养大学生正确的体育参与动机的一些想法,以供广大体育工作者参考。 相似文献
63.
L. Berkowitz and E. Harmon-Jones (see record 2004-15096-001) challenge appraisal theories of emotion by describing 2 sets of conditions (physical discomfort and anger-related muscle actions) in which anger appears to be elicited in the absence of theoretically predicted appraisals. In response, the authors discuss the ability of the specific appraisal model they have developed (e.g., C. A. Smith & L. D. Kirby, 2000, 2001; C. A. Smith & R. S. Lazarus, 1990) to account for such instances of anger. First, a number of issues are clarified relevant to the authors' model, including the nature of both the cognitive operations underlying appraisal and the specific appraisals hypothesized to evoke anger. The authors then describe how their model can account for the instances of anger described by L. Berkowitz and E. Harmon-Jones and how both accounts might be tested. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
64.
Jaroslav Mackerle 《International Journal of Pressure Vessels and Piping》1996,69(3):279-339
The paper gives a bibliographical review of the finite element methods (FEMs) applied for the analysis of pressure vessel structures/components and piping from the theoretical as well as practical points of view. The range of applications of FEMs in this area is wide and cannot be presented in a single paper; therefore the aim of this review is to give the reader an encyclopaedic view of the differnt possibilities that exist today for the finite element analysis in the fields of pressure vessels and piping. The bibliography at the end of the paper contains approximately 1900 references to papers, conference proceedings and theses/dissertations on the subject that were published in 1976–1996. These are classified in the following categories: linear and non-linear, static and dynamic, stress and deflection analysis; stability problems; thermal problems; fracture mechanics problems; contact problems; fluid-structure interaction problems; manufacturing of pipes and tubes; welded pipes and pressure vessel components; development of special finite elements for pressure vessels and pipes; finite element software; and other topics. Also finite element software, general purpose and special purpose codes, used for the analysis of pressure vessels and pipes are briefly discussed and presented. 相似文献
65.
A.P.S. Selvadurai 《Engineering Analysis with Boundary Elements》1996,17(4):287-294
The paper examines the problem of a penny-shaped crack which is formed by the development of a crack in both the fibre and the matrix of a composite consisting of an isolated elastic fibre located in an elastic matrix of infinite extent. The composite region is subjected to a uniform strain field in the direction of the fibre. The paper presents two integral-equation based approaches for the analysis of the problem. The first approach considers the formulation of the complete integral equations governing the associated elasticity problem for a two material region. The second approach considers the boundary integral equation formulation of the problem. Both methods entail the numerical solution of the governing integral equations. The solutions to these integral equations are used to evaluate the stress intensity factor at the boundary of the penny-shaped crack. 相似文献
66.
Rein Smedinga 《Discrete Event Dynamic Systems》1993,2(3-4):265-297
To model qualitative aspects of discrete event systems, i.e., the order of the events is of sole importance, we use a triple consisting of the set of all possible events (the alphabet), the set of all behavior (possible strings of events), and the set of all tasks (completed behavior). We use this view to model synchronous as well as asynchronous connection of systems. Moreover, it is easy to define notions like deadlock and livelock in this view. We give a method to construct a second system that, in connection with the original system, gets rid of its deadlock and/or livelock. A state-space representation is introduced. In this representation computations can be done effectively. 相似文献
67.
68.
在对影响体育教学质量的几种环境因素分析的基础上,提出了克服体育实践教学环境 因素的消极影响的主要措施以及正确利用这些物理因素的积极作用。 相似文献
69.
Y. C. Wu Darning Feng W. F. Koch 《Journal of research of the National Institute of Standards and Technology》1991,96(6):757-762
Ionic interactions in the two systems NaCl-HEPES (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid) and NaCl-MOPSO (3-(N-Morpholino)-2-hydroxypropanesulfonic acid) have been studied in terms of their mutual influence on the respective activity coefficients of each component. Activity coefficients for each component of the two systems and for corresponding buffers are calculated from emf measurements of solutions containing NaCl, the aminosulfonic acid, and its conjugate base in a NalSE/solution/AgCl-Ag cell at 5, 15, 25, and 37 °C. 相似文献
70.
HHD型核子秤电离室已成功地使用于HCS型核子秤.对它的各种物理性能指标进行了检测,各项性能指标都达到了设计要求。 相似文献