全文获取类型
收费全文 | 5187篇 |
免费 | 213篇 |
国内免费 | 5篇 |
学科分类
工业技术 | 5405篇 |
出版年
2023年 | 31篇 |
2022年 | 80篇 |
2021年 | 130篇 |
2020年 | 90篇 |
2019年 | 90篇 |
2018年 | 109篇 |
2017年 | 102篇 |
2016年 | 140篇 |
2015年 | 104篇 |
2014年 | 137篇 |
2013年 | 318篇 |
2012年 | 253篇 |
2011年 | 284篇 |
2010年 | 242篇 |
2009年 | 246篇 |
2008年 | 272篇 |
2007年 | 262篇 |
2006年 | 182篇 |
2005年 | 169篇 |
2004年 | 168篇 |
2003年 | 126篇 |
2002年 | 130篇 |
2001年 | 102篇 |
2000年 | 99篇 |
1999年 | 96篇 |
1998年 | 180篇 |
1997年 | 146篇 |
1996年 | 103篇 |
1995年 | 93篇 |
1994年 | 79篇 |
1993年 | 77篇 |
1992年 | 60篇 |
1991年 | 53篇 |
1990年 | 66篇 |
1989年 | 49篇 |
1988年 | 56篇 |
1987年 | 46篇 |
1986年 | 37篇 |
1985年 | 39篇 |
1984年 | 30篇 |
1983年 | 39篇 |
1982年 | 20篇 |
1981年 | 30篇 |
1979年 | 19篇 |
1978年 | 25篇 |
1977年 | 25篇 |
1976年 | 28篇 |
1975年 | 23篇 |
1974年 | 19篇 |
1973年 | 17篇 |
排序方式: 共有5405条查询结果,搜索用时 0 毫秒
1.
A micromechanics analysis is performed for the determination of the five independent elastic moduli of unidirectional fiber composites. By considering viscoelastic phases and by using the correspondence principle and the inversion of the Laplace transform, the five time-dependent functions which characterize the effective behavior of viscoelastic composites are established. The predicted time-dependent behavior is applied for the analysis of viscoelastic laminated plates. The resulting viscoelastic effects are shown, and comparison between the results obtained within the classical laminated plate theory and the first-order shear deformation theory is discussed. 相似文献
2.
Jacob Hooker David Hinks Gerardo Montero Christopher Conlee 《Coloration Technology》2002,118(6):273-276
The synthesis of azo dyes via a conventional aqueous-based diazotisation and coupling reaction requires the use of relatively high concentrations of mineral acids, which leads to high electrolyte concentrations in wastewater. Reported in this paper is an environmentally benign one-pot method for the synthesis of a nonionic azo dye, N,N -diethyl- N -{4-[( E )-(4-nitrophenyl)diazenyl]phenyl}amine, in supercritical carbon dioxide without using a mineral acid. The product yield increased significantly with temperature, with 91% theoretical yield afforded at 80 °C. The pressure of the system had little influence on product yield. 相似文献
3.
4.
5.
6.
Yi‐Hung Chen Ching‐Yuan Chang Wei‐Ling Su Chun‐Yu Chiu Yue‐Hwa Yu Pen‐Chi Chiang Chiung‐Fen Chang Je‐Lueng Shie Chyow‐San Chiou Sally IM Chiang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(1):68-75
This study investigates the ozonation of CI Reactive Black 5 (RB5) by using the rotating packed bed (RPB) and completely stirred tank reactor (CSTR) as ozone contactors. The RPB, which provides high gravitational force by adjusting the rotational speed, was employed as a novel ozone contactor. The same ozone dosage was separately introduced into either the RPB or the CSTR for the investigation, while the experimental solution was continuously circulated within the apparatus consisting of the RPB and CSTR. The decolorization and mineralization efficiencies of RB5 in the course of ozonation are compared for these two methods. Moreover, the dissolved and off‐gas ozone concentrations were simultaneously monitored for the further analysis. As a result, the ozone mass transfer rate per unit volume of the RPB was significantly higher because of its higher mass transfer coefficient and gas–liquid concentration driving force. Furthermore, ozonation kinetics was found to be independent of the gravitational magnitude of an ozone gas–liquid contactor. Therefore, the results suggest employing RPBs as ozone‐contacting devices with the advantage of volume reduction. The experimental results, which can be used for further modeling of the ozonation process in the RPB, also show the requirement of correct design for the RPB. Consequently, the present study is useful for the understanding of practical application of RPBs. Copyright © 2004 Society of Chemical Industry 相似文献
7.
Fractal geometry is finding its application in the nondestructive evaluation (NDE) of corrosion by characterizing the corrosion surface with fractal dimensions. It was found that corrosion surfaces can be well described by multifractals. Two algorithms were used to obtain the fractal dimensions of a corroded aluminum alloy surface, one being box-counting and another being coherent light scattering. Fractal dimensions were related with the damage caused by corrosion and fatigue. 相似文献
8.
Gader P.D. Mohamed M. Jung-Hsien Chiang 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》1997,27(1):158-164
An off-line handwritten word recognition system is described. Images of handwritten words are matched to lexicons of candidate strings. A word image is segmented into primitives. The best match between sequences of unions of primitives and a lexicon string is found using dynamic programming. Neural networks assign match scores between characters and segments. Two particularly unique features are that neural networks assign confidence that pairs of segments are compatible with character confidence assignments and that this confidence is integrated into the dynamic programming. Experimental results are provided on data from the U.S. Postal Service. 相似文献
9.
F F?ndrich AM Waaga J Schr?der E Schweizer A Schmid S Jacob HH Wacker P Schroeder 《Canadian Metallurgical Quarterly》1995,27(2):1553-1554
10.
This study addressed the issue of adjustment among Holocaust survivors by multidimensional assessment of subjective well-being (SWB). Participants were Israeli Holocaust survivors incidentally included in a life-span study (Group 1; n?=?466) or purposely approached for studying Holocaust survivors (Group 2; n?=?178). Comparison participants had immigrated to Israel before World War II, with their parents either undergoing (Group 3; n?=?270) or not undergoing the Holocaust (Group 4; n?=?388); other comparison participants had immigrated after the war with parents not undergoing the Holocaust (Group 5; n?=?166). Results showed that Group 1 scored lower than Group 2, mainly in positive affect. Group 1 scored lower than Group 4, and to a lesser extent also lower than Groups 3 and 5, mainly in aging-related themes of SWB. The study suggests that long-term effects of the Holocaust on the survivors' SWB are traceable but require a differential approach to the study groups and to the facets of SWB. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献