全文获取类型
收费全文 | 26777篇 |
免费 | 686篇 |
国内免费 | 34篇 |
专业分类
电工技术 | 329篇 |
综合类 | 14篇 |
化学工业 | 5922篇 |
金属工艺 | 516篇 |
机械仪表 | 464篇 |
建筑科学 | 1159篇 |
矿业工程 | 332篇 |
能源动力 | 650篇 |
轻工业 | 1726篇 |
水利工程 | 226篇 |
石油天然气 | 245篇 |
无线电 | 1713篇 |
一般工业技术 | 4078篇 |
冶金工业 | 6149篇 |
原子能技术 | 265篇 |
自动化技术 | 3709篇 |
出版年
2022年 | 246篇 |
2021年 | 413篇 |
2020年 | 266篇 |
2019年 | 346篇 |
2018年 | 423篇 |
2017年 | 370篇 |
2016年 | 485篇 |
2015年 | 391篇 |
2014年 | 614篇 |
2013年 | 1651篇 |
2012年 | 937篇 |
2011年 | 1201篇 |
2010年 | 922篇 |
2009年 | 971篇 |
2008年 | 1148篇 |
2007年 | 1063篇 |
2006年 | 973篇 |
2005年 | 881篇 |
2004年 | 743篇 |
2003年 | 711篇 |
2002年 | 705篇 |
2001年 | 485篇 |
2000年 | 390篇 |
1999年 | 447篇 |
1998年 | 440篇 |
1997年 | 428篇 |
1996年 | 473篇 |
1995年 | 443篇 |
1994年 | 451篇 |
1993年 | 436篇 |
1992年 | 431篇 |
1991年 | 271篇 |
1990年 | 410篇 |
1989年 | 387篇 |
1988年 | 336篇 |
1987年 | 404篇 |
1986年 | 348篇 |
1985年 | 441篇 |
1984年 | 463篇 |
1983年 | 398篇 |
1982年 | 375篇 |
1981年 | 297篇 |
1980年 | 298篇 |
1979年 | 357篇 |
1978年 | 299篇 |
1977年 | 238篇 |
1976年 | 217篇 |
1975年 | 245篇 |
1974年 | 217篇 |
1973年 | 224篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Examined the 10 most cited articles published in the Psychological Bulletin over the past 4 decades. Seven of the 10 articles were methodologically oriented. A survey of the authors revealed that highly cited articles have an important message that goes beyond momentary fads, are broad in topic and intended audience, accessible, and well written. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
32.
33.
Determination of temperatures associated with room fires provides a means of assessing an important aspect of fire hazard: the likelihood of the occurrence of flashover. Layer temperatures in excess of 600°C have been associated with the occurrence of flashover. A data correlation has previously been presented to estimate layer temperatures for fires burning in the center of rooms. For fires in corners and along walls, restricted entrainment results in higher layer temperatures than predicted by the previous correlation. Modification factors for the previous correlation are developed to extend its applicability to wall and corner burning geometries. The present analysis suggests that a fire in a corner may cause flashover with only half the heat release rate necessary for a fire burning in the center of a room.
Reference: Frederick Mowrer and Robert Williamson, Estimating Room Temperatures from Fires along Walls and in Corners,Fire Technology, Vol. 23, May 1987, pp. 133–145. 相似文献
34.
Railway Engineering Science - Electrified railways are becoming a popular transport medium and these consume a large amount of electrical energy. Environmental concerns demand reduction in energy... 相似文献
35.
Robert F. Brebrick 《Journal of Phase Equilibria and Diffusion》2006,27(5):445-451
The author’s previously published partial pressures of tellurium over tellurium-rich CdTe are reanalyzed to yield new solidus
points as well as temperatures and partial pressures for compositions within the homogeneity range. Although the results are
qualitatively the same as before, they are more satisfactory in that some thermodynamic inconsistencies have been removed.
The composition range of the CdTe phase extends slightly beyond the equal atom fraction,X
Te=0.5, to a Te-rich composition of (X
Te−0.5)=(1 to 7)×10−5. The data are in fair agreement with that obtained from total pressure measurements at generally higher compositions. Since
both types of measurement are near the limits of attainable accuracy, their agreement would seem to confirm the essential
correctness of both. 相似文献
36.
An interactive computer program is introduced in order to make a simultaneous graphical presentation of phase boundaries and their corresponding free energy curves. The program, which uses a graphics display terminal, is a useful tool in teaching thermodynamic concepts involved in phase diagrams, especially for undergraduate students. 相似文献
37.
Jones Robert M. Webster John G. Keesey Ulker Tulunay 《IEEE transactions on bio-medical engineering》1972,(1):29-33
In normal vision, eye movements cause the image to move on the retina. Special apparatus can stabilize the image on the retina so it cannot move, and vision fades away. Previous methods for stabilizing the image were either optical systems or complex computer-controlled feedback systems. A simpler feedback system is presented which detects eye motion and rotates a mirror through which the target is viewed, to exactly compensate for eye motion. Unlike previous optical systems, this new system has no lenses in either the viewing or the image-forming path to limit the spatial resolution. 相似文献
38.
Smith Robert El. Wekstein David R. Sullivan Robert H. 《IEEE transactions on bio-medical engineering》1970,(2):151-156
A multiplexing, demodulating, and recording telemetry system designed to process multiple pulse-coded temperature channels is described. The system provides complete control of recording and multiplexing sequences and timing, and gives a single analog signal in response to each sample of pulse-coded data. It identifies all channels and indicates to a computer when a new data sample is to be processed. The system is self-calibrating to maintain accuracy over extended data collection periods, and is inexpensive. 相似文献
39.
Frank C. Magne James A. Harris Robert A. Pittman Evald L. Skau 《Journal of the American Oil Chemists' Society》1966,43(9):519-524
The stepwise HBr titration method for the cyclopropenoid analysis of cottonseed oils is subject to serious inaccuracies when
applied to samples containing higher cyclopropenoid concentrations, particularly if they contain appreciable amounts of alumina-adsorbable
materials. A modification of the method is described which eliminates these sources of error. Its validity has been established
by the analysis of a wide range of synthetic compositions including compositions containing massive amounts of interfering
HBr-reactive substances and other alumina-adsorbable materials. The method with further modification can be used to analyze
glycerides with the same high degree of accuracy.
Presented at the AOCS Meeting in Houston, April 1965.
So. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献
40.
Laura M. Russell Lloyd F. Johnson D. P. H. Hasselman Robert Ruh 《Journal of the American Ceramic Society》1987,70(10):226-C
The thermal conductivity and diffusivity of silicon carbide whisker reinforced mullite was shown to increase with whisker content. This effect was much greater for vapor-liquid-solid (VLS) whiskers than for rice-hull (RH) whiskers. This suggests that the thermal conductivity for the VLS whiskers was significantly higher than for the RH whiskers. Due to preferred orientation of the whiskers, thermal conductivity and diffusivity of the composite samples exhibited significant anisotropy. 相似文献