全文获取类型
收费全文 | 2247篇 |
免费 | 128篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 31篇 |
综合类 | 5篇 |
化学工业 | 634篇 |
金属工艺 | 62篇 |
机械仪表 | 37篇 |
建筑科学 | 195篇 |
矿业工程 | 4篇 |
能源动力 | 85篇 |
轻工业 | 179篇 |
水利工程 | 16篇 |
石油天然气 | 7篇 |
无线电 | 165篇 |
一般工业技术 | 450篇 |
冶金工业 | 89篇 |
原子能技术 | 12篇 |
自动化技术 | 407篇 |
出版年
2023年 | 28篇 |
2022年 | 54篇 |
2021年 | 79篇 |
2020年 | 48篇 |
2019年 | 68篇 |
2018年 | 53篇 |
2017年 | 57篇 |
2016年 | 86篇 |
2015年 | 87篇 |
2014年 | 106篇 |
2013年 | 162篇 |
2012年 | 141篇 |
2011年 | 195篇 |
2010年 | 104篇 |
2009年 | 133篇 |
2008年 | 142篇 |
2007年 | 131篇 |
2006年 | 103篇 |
2005年 | 83篇 |
2004年 | 85篇 |
2003年 | 51篇 |
2002年 | 59篇 |
2001年 | 31篇 |
2000年 | 35篇 |
1999年 | 30篇 |
1998年 | 18篇 |
1997年 | 20篇 |
1996年 | 26篇 |
1995年 | 21篇 |
1994年 | 15篇 |
1993年 | 13篇 |
1992年 | 15篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 16篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1970年 | 3篇 |
1934年 | 1篇 |
排序方式: 共有2378条查询结果,搜索用时 0 毫秒
981.
982.
983.
Jean-Marc Linares Julien Chaves-Jacob Heinrich Schwenke Andrew Longstaff Simon Fletcher Jakob Flore Eckart Uhlmann Jens Wintering 《Precision Engineering》2014
This paper deals with the accuracy of compensation of machine tools using a tracking interferometer using the multilateration method. The measurement strategy and thermal drift compensation of the measurements are studied. It shows that most effects of temperature are accurately compensated by the laser tracking interferometer software. However, thermal drifts of accessories are not taken into account, and are therefore not corrected. To validate the robustness of procedures, the geometrical errors of the same machine tool were measured by five measurement strategies using the same equipment. Each strategy is devised and carried out independently by a different person from several institutions. For each strategy, the geometrical compensations were applied to a set of nominal tool path points. The difference, between the nominal points and the compensated or uncompensated points was calculated. This criterion was used to discuss the procedures employed by the participants. 相似文献
984.
Alessandro Schönborn Parisa Sayad Alexander A. Konnov Jens Klingmann 《International Journal of Hydrogen Energy》2014
Autoignition of hydrogen in air was studied in a turbulent flow reactor using OH*-chemiluminescence. High-speed imaging was used to visualise the formation of autoignition kernels in the flow, and to analyse the conditions under which temporary stabilisation of the flame kernels occurred. The experiments were carried out at temperatures of 800–850 K, pressures of 0.8–1.2 MPa and an equivalence ratio of φ = 0.25. Measurements of the autoignition delays yielded values in the range of τ = 210–447 ms. The autoignition delay results indicated that, over the range of conditions studied, ignition delays reduced with decreasing pressure. This observation contradicted homogeneous gas-phase kinetic calculations, which predicted an increase in autoignition delay with decreasing pressure. If the kinetic model was altered to include surface reactions at the reactor walls, the calculations could be qualitatively reconciled with the experimental data, suggesting that wall reactions had a significant influence on autoignition delays. 相似文献
985.
In this paper, we propose a tabu search algorithm for the resource-constrained project scheduling problem with transfer times. Solutions are represented by resource flows extending the disjunctive graph model for shop scheduling problems. Neighborhoods are defined by parallel and serial modifications rerouting or reversing flow on certain arcs. This approach is evaluated from a theoretical and experimental point of view. Besides studying the connectivity of different neighborhoods, computational results are presented for benchmark instances with and without transfer times. 相似文献
986.
A simple atmospheric boundary layer model applied to large eddy simulations of wind turbine wakes 总被引:1,自引:0,他引:1
A simple model for including the influence of the atmospheric boundary layer in connection with large eddy simulations of wind turbine wakes is presented and validated by comparing computed results with measurements as well as with direct numerical simulations. The model is based on an immersed boundary type technique where volume forces are used to introduce wind shear and atmospheric turbulence. The application of the model for wake studies is demonstrated by combining it with the actuator line method, and predictions are compared with field measurements. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
987.
Coffee consumption rapidly reduces background DNA strand breaks in healthy humans: Results of a short‐term repeated uptake intervention study 下载免费PDF全文
988.
Physics and Technological Aspects of Radio‐Frequency Ion Thrusters Electric space propulsion devices offer a propellant utilization efficiency orders of magnitude higher than chemical ones. This, among other benefits, motivates the usage of electric propulsion for station keeping, attitude and orbit control, orbit raising and interplanetary deep space missions. In particular, radio‐frequency ion thrusters (RIT) offer even higher efficiency than comparable electric thrusters. This is mainly due to electrostatically generated thrust in RITs which is decoupled from plasma generation which again is ultimately necessary for the production of thrust‐generating requency Ion Thrusters ions. This article gives insight into basic physical processes that occur within the thrusters' discharge vessels which lead to highly efficient, highly resolvable thrust generation. Furthermore, a more general systems engineering observation of the complete thruster system is given with special respect to the radio‐frequency generator (RFG) which is essential to take into account when speaking of overall efficiency. Finally, an overview on alternative propellants to possibly increase cost efficiency of a particular mission is proposed. 相似文献
989.
990.
Jens Knocke 《Building Research & Information》1988,16(5):283-285
Jens Knocke of the National Swedish Institute of Building Research and coordinator of the commission of 75 experts from 25 countries demonstrates how 'builders' all over the world are open to legal action if their product, the building, with its installations and landscaping fails to satisfy any of a long range of 'user' requirements. 相似文献