全文获取类型
收费全文 | 12731篇 |
免费 | 1067篇 |
国内免费 | 812篇 |
专业分类
电工技术 | 427篇 |
技术理论 | 1篇 |
综合类 | 1373篇 |
化学工业 | 1391篇 |
金属工艺 | 152篇 |
机械仪表 | 317篇 |
建筑科学 | 493篇 |
矿业工程 | 239篇 |
能源动力 | 542篇 |
轻工业 | 385篇 |
水利工程 | 167篇 |
石油天然气 | 589篇 |
武器工业 | 45篇 |
无线电 | 2138篇 |
一般工业技术 | 934篇 |
冶金工业 | 370篇 |
原子能技术 | 109篇 |
自动化技术 | 4938篇 |
出版年
2024年 | 43篇 |
2023年 | 129篇 |
2022年 | 198篇 |
2021年 | 338篇 |
2020年 | 418篇 |
2019年 | 243篇 |
2018年 | 269篇 |
2017年 | 354篇 |
2016年 | 444篇 |
2015年 | 408篇 |
2014年 | 692篇 |
2013年 | 815篇 |
2012年 | 772篇 |
2011年 | 857篇 |
2010年 | 705篇 |
2009年 | 766篇 |
2008年 | 769篇 |
2007年 | 928篇 |
2006年 | 847篇 |
2005年 | 845篇 |
2004年 | 692篇 |
2003年 | 710篇 |
2002年 | 525篇 |
2001年 | 425篇 |
2000年 | 344篇 |
1999年 | 280篇 |
1998年 | 191篇 |
1997年 | 131篇 |
1996年 | 99篇 |
1995年 | 89篇 |
1994年 | 71篇 |
1993年 | 39篇 |
1992年 | 34篇 |
1991年 | 19篇 |
1990年 | 16篇 |
1989年 | 24篇 |
1988年 | 20篇 |
1987年 | 7篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1965年 | 1篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1958年 | 1篇 |
1957年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
Rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) measurements have been undertaken to study the behaviour of pure aluminum electrodes in alkaline media. The measurements did consist of linear sweep voltammetry from anodic to cathodic potentials on 4N, 5N or 5N5-aluminum samples in 4 M aqueous potassium hydroxide solution. In the potential range studied (−0.7 V versus NHE to −2.5 V versus NHE) the aluminum undergoes oxidation/dissolution into aluminates anions at high electrode potential while it yields strong hydrogen evolution at low potentials. Thanks to the RRDE technique, we show that hydrogen starts to evolve from the aluminum electrode even above the open circuit potential. Also, the oxidation state of superficial aluminum varies according to the electrode potential: whereas non-conducting aluminum oxides are present above the open-circuit potential hindering hydrogen evolution reaction (HER), they tend to disappear below the ocp, due to the strong hydrogen evolution, following the probable porous oxide layer blow up induced by the hydrogen bubbles formation. In consequence at very low potential, HER occurs on bare aluminum, HER kinetics being much faster than on oxide-covered aluminum. 相似文献
152.
The inverse problem approach by conjugate gradient with adjoint equations is adapted to the context of a non-isothermal bioprocess, controlled by internal heat generation from microbial oxidation, as could be found in a composting reactor for instance, to determine the heat source from internal temperature measurements. The volumetric heat source is assumed proportional to the rate of consumption of a substrate by a biomass, as described by a Monod model. Computations are performed for Rayleigh numbers equal to 0.25 and 25, for a representative biochemical reaction under typical boundary conditions, for constant and temperature-dependent model parameters. The influence of noisy input data is also considered. It is found that good solutions can be obtained when heat release and diffusion occur over very different time scales. The variation of the model parameters with temperature must be taken into account, but single sensor solutions are possible at relatively small Rayleigh numbers when convection is present. 相似文献
153.
Benedikt Ley Corinna Ogonowski Jan Hess Tim Reichling Lin Wan Volker Wulf 《Behaviour & Information Technology》2014,33(8):815-828
Technological infrastructure at home is changing continuously and is becoming increasingly interconnected. Media devices, including the TV set, provide access to the Internet and offer manifold opportunities to consume media on demand. Additionally, personal devices, such as smartphones, also enable flexible consumption and sharing of media. Questions about how these technologies change the user's media usage and how these changes affect the social structure of a household, however, remain largely unanswered. In order to gain insight into the adoption of new technologies into daily routines, we explored these changes in respect of people's media usage in a qualitative long-term Living Lab study. We will present findings regarding personal routines, flexible integration of new devices into existing practices, influences on households as social systems and related issues in device access and collective use. We will highlight potentials and conflicts regarding device shifts and roles; restrictions in device access; social influences in the living room; and individual changes in media consumption. 相似文献
154.
A. V. Fedorov 《Combustion, Explosion, and Shock Waves》2004,40(1):17-31
A review is made of uptodate investigations in the field of physicomathematical modeling of mixing of solid particles with highvelocity gas flows arising under the action on shock waves, compression waves, and expansion waves on unstable dust deposits on the boundaries of channels or plates and in cavities, as well as on free clouds of particles. In particular, experiments in shock tubes with particles initially located in cavities and on surfaces are described. The experimental data presented in the form of distributions of particle concentrations at various points of space above the unstable layer, pressure distributions on the lower wall of the shock tube, etc., are used for verification of proposed mathematical models in regimes of single particles, interacting continua, and turbulent diffusion. An analysis of experimental and numerical data shows that the models considered sometimes allow adequate identification of the wave structure of motion of the mixture and the field of parameters inside and outside the layer. 相似文献
155.
This paper considers human server systems of queues that arise within the information technology services industry. We develop a two-phase stochastic optimization solution approach to effectively and efficiently address the capacity management and planning processes of information technology services delivery centers. A large collection of numerical experiments of real-world human server system environments investigates various issues of both theoretical and practical interest, quantifying the significant benefits of our approach as well as evaluating the financial-performance trade-offs often encountered in practice. 相似文献
156.
Marika Lüders Asbjørn Følstad Espen Waldal 《Journal of Computer-Mediated Communication》2014,19(3):446-462
Social media are often argued to change political communication, decreasing the distance between politicians and citizens, and increasing citizens' influence on policymaking. This paper presents findings from a study of how the Norwegian Labour Party uses social media, focusing on the community platform MyLabourParty. Interviews with politicians and a survey with citizens as respondents were conducted to examine the experiences of online political discussions. Findings show that citizens and politicians expect MyLabourParty to strengthen citizen participation. Yet, citizens still experience communication asymmetry and politicians may find it challenging to participate to the extent citizens expect. Means for bridging the gap between expectations and experiences are called for, in particular redefinition of the offering, changes of user‐practices, and system improvements. 相似文献
157.
158.
本文针对外贸型企业对外贸易服务流程中的资金流动和资金流管理中存在的问题,设计了一个基于Web的外贸企业资金流管理平台,实现跨地域、多角色、实时的资金流录入、统计和分析,使企业能够高效准确地管理业务和资金流,能够随时统计资金的流向以及分析盈利情况;着重论述外贸企业资金流管理需求、基于Web的系统框架设计、数据加密存储、加密传输、用户角色及权限控制等。 相似文献
159.
160.
Exe类型电子书制作软件集成文字内容和小图片非常容易,效果也很不错,但是对集成高品质的音视频、数码照片等大容量数据文件却无能为力。通过对iebook超级精灵自带模板以及Exe电子书文件的深入分析,把flash技术、流媒体对象和file协议有机结合,实现动态加载指定相对路径下的外部视频文件到电子书中,大大提高了iebook超级精灵在处理多媒体方面的实用性。 相似文献