全文获取类型
收费全文 | 5419篇 |
免费 | 357篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 43篇 |
综合类 | 7篇 |
化学工业 | 1363篇 |
金属工艺 | 71篇 |
机械仪表 | 110篇 |
建筑科学 | 269篇 |
矿业工程 | 7篇 |
能源动力 | 95篇 |
轻工业 | 964篇 |
水利工程 | 54篇 |
石油天然气 | 27篇 |
无线电 | 282篇 |
一般工业技术 | 840篇 |
冶金工业 | 874篇 |
原子能技术 | 21篇 |
自动化技术 | 756篇 |
出版年
2024年 | 12篇 |
2023年 | 49篇 |
2022年 | 158篇 |
2021年 | 195篇 |
2020年 | 103篇 |
2019年 | 149篇 |
2018年 | 178篇 |
2017年 | 145篇 |
2016年 | 190篇 |
2015年 | 117篇 |
2014年 | 231篇 |
2013年 | 364篇 |
2012年 | 301篇 |
2011年 | 407篇 |
2010年 | 257篇 |
2009年 | 236篇 |
2008年 | 261篇 |
2007年 | 247篇 |
2006年 | 244篇 |
2005年 | 160篇 |
2004年 | 156篇 |
2003年 | 141篇 |
2002年 | 136篇 |
2001年 | 78篇 |
2000年 | 83篇 |
1999年 | 85篇 |
1998年 | 137篇 |
1997年 | 98篇 |
1996年 | 102篇 |
1995年 | 72篇 |
1994年 | 66篇 |
1993年 | 51篇 |
1992年 | 57篇 |
1991年 | 48篇 |
1990年 | 56篇 |
1989年 | 39篇 |
1988年 | 41篇 |
1987年 | 33篇 |
1986年 | 24篇 |
1985年 | 27篇 |
1984年 | 35篇 |
1983年 | 22篇 |
1982年 | 28篇 |
1980年 | 17篇 |
1979年 | 26篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1976年 | 18篇 |
1975年 | 17篇 |
1969年 | 9篇 |
排序方式: 共有5783条查询结果,搜索用时 31 毫秒
41.
J. M. P. Q. Delgado 《加拿大化工杂志》2006,84(6):651-655
In this article, a simple and inexpensive experimental technique easy to build in laboratory, for the measurement of tortuosity of a packed bed of inert particles, is described. Experimental values of the tortuosity were obtained with four different packed beds of sand. The experimental results obtained are in good agreement with the theoretical values of tortuosity in a porous media; and the data reported showed the tortuosity to increase with decrease in the void fraction of the packed bed as expected. 相似文献
42.
43.
Todd Michael; Armeli Stephen; Tennen Howard; Carney Margaret Anne; Affleck Glenn 《Canadian Metallurgical Quarterly》2003,17(4):303
Data from 2 daily diary studies of stress, negative affect, and drinking were used to examine the correspondence between global self-reports of drinking to cope (DTC) and within-person stress/negative affect-drinking associations. In Study 1, 83 community-residing drinkers recorded data in nightly booklets on negative events, perceived stress, negative affect, and drinking for 60 consecutive days. In Study 2, 88 community-residing drinkers recorded data on negative events and negative interpersonal exchanges nightly and negative affect and drinking in near-real time on palmtop computers for 30 consecutive days. Both studies showed only modest correspondence between self-reported DTC and between-person differences in within-day, daily, and weekly associations between stress/negative affect and drinking. The findings indicate that individuals who report higher DTC simply may drink across a wider variety of conditions than those who report relatively lower DTC. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
44.
Anne Venu Gopal Research Scholar P. Venkateswara Rao Associate Professor 《The International Journal of Advanced Manufacturing Technology》2004,24(11-12):816-820
The chip-thickness models, used to assess the performance of grinding processes, play a major role in predicting the surface quality. In the present paper, an attempt has been made to develop a new chip-thickness model for the performance assessment of silicon carbide grinding by incorporating the modulus of elasticities of the grinding wheel and the workpiece in the existing basic chip-thickness model to account for elastic deformation. The new model has been validated by conducting experiments, taking the surface roughness as a parameter of evaluation . 相似文献
45.
Anne Mahoney 《Computers and the Humanities》2003,37(4):469-473
This paper describes an encoding for representing quantitativemetrical analyses in TEI SGML or XML documents, using only charactersfrom the standard keyboard set, and a system for converting thisencoding to other forms for display. 相似文献
46.
Didier Perrin Céline Guillermain Anne Bergeret José-Marie Lopez-Cuesta Gilles Tersac 《Journal of Materials Science》2006,41(12):3593-3602
A new process of management of waste of composite materials from Sheet Moulding Compounds (SMC), as reinforcing fillers for
thermoplastic materials, including both mechanical and chemical processes is proposed in this paper. Communited SMC being
composed of coated glass fibres intimately mixed with calcium carbonate powder, their reinforcing power is low. First, the
fibrous part was increased by partial dissolution of calcium carbonate present in the crushed products SMC. Second, a process
of partial solvolysis was developed aiming at strong increasing the interfacial mechanical properties by functionalising of
SMC load incorporated into polypropylene/grafted maleic anhydride polypropylene (PP/PPgma). At this effect, we investigated a treatment with a hot triamine (diethylenetriamine, DETA) in order to create a functionalisation,
after scission of the bond ester of unsaturated polyester, as bridging amino-succinimide.The effect of this recycling way
by partial solvolysis was checked from the mechanical properties of the resulting reinforced PP/PPgma material: Although a lower of Young modulus, better yield stress and especially resilience were observed. 相似文献
47.
A. T. Sousa P. S. Fialho C. A. Nieto de Castro R. Tufeu B. Le Neindre 《International Journal of Thermophysics》1996,17(3):551-560
The density of HCFC 141b has been measured at several temperatures between 260 and 320 K, Mid pressures up to 20 MPa, with a mechanical oscillator densimeter. The densimeter was calibrated with 2,2,4-trimethylpentane, whose density was obtained from a correlating cyuation with 0.3% uncertainty. The density data obtained for HCFC 14H) hits a reproducibility of 0.05% and an uncertainty of 0.3%. The data obtained were fitted to a Tait-type equation. which reproduced the experimental densities within 0.11 % and were compared with the data obtained in other works.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A. 相似文献
48.
Steven S Fu Miles McFall Andrew J Saxon Jean C Beckham Timothy P Carmody Dewleen G Baker Anne M Joseph 《Nicotine & tobacco research》2007,9(11):1071-1084
We conducted a systematic review of what is known about the relationship between post-traumatic stress disorder (PTSD) and smoking to guide research on underlying mechanisms and to facilitate the development of evidence-based tobacco treatments for this population of smokers. We searched Medline, PsychINFO, and the Cochrane Central Register of Controlled Trials and identified 45 studies for review that presented primary data on PTSD and smoking. Smoking rates were high among clinical samples with PTSD (40%-86%) as well as nonclinical populations with PTSD (34%-61%). Most studies showed a positive relationship between PTSD and smoking and nicotine dependence, with odds ratios ranging between 2.04 and 4.52. Findings also suggest that PTSD, rather than trauma exposure itself, is more influential for increasing risk of smoking. A small but growing literature has examined psychological factors related to smoking initiation and maintenance and the overlapping neurobiology of PTSD and nicotine dependence. Observational studies indicate that smokers with PTSD have lower quit rates than do smokers without PTSD. Yet a few tobacco cessation treatment trials in smokers with PTSD have achieved quit rates comparable with controlled trials of smokers without mental disorders. In conclusion, the evidence points to a causal relationship between PTSD and smoking that may be bidirectional. Specific PTSD symptoms may contribute to smoking and disrupt cessation attempts. Intervention studies that test behavioral and pharmacological interventions designed specifically for use in patients with PTSD are needed to reduce morbidity and mortality in this population. 相似文献
49.
Anne J. Kershen 《Landscape Research》2004,29(3):261-275
For hundreds of years Spitalfields, the 250 acres that border the London Borough of Tower Hamlets and the City of London, has been a first point of settlement for immigrants. Its tradition of political and religious non-conformity and its proximity to the City of London and the docks have acted as a unique beacon to those seeking refuge and economic opportunity in a capital city. Spitalfields has provided a landscape upon which the incomers have engraved a 'home away from home', for themselves and their families. Using the 'Spitalfields experience' as a focal point, the concept and construction of home by migrants in the diaspora is explored, and some of the cultural tools that the Huguenots, eastern European Jews and Bangladeshis—the protagonist subject groups of this essay—have used to construct their homes in the elsewhere are examined. Due to the spatial limitations of this work, language, diet and religion have been selected as the topics under the microscope. All three facilitated the maintenance of links with the sending societies whilst, in some, though not in every instance, creating a bridge to assimilation. The usage and effectiveness of these tools is compared and contrasted and the role played by Spitalfields over the past four centuries in the creation of homes by those in an alien environment is assessed. 相似文献
50.
J.M.P.Q. Delgado 《Journal of Phase Equilibria and Diffusion》2007,28(5):427-432
Molecular (or tracer) diffusion coefficient data were obtained for 2-naphthol, benzoic acid, salicylic acid, camphor, and
cinnamic acid in water at temperatures that differ significantly from ambient value. Experimental values were determined for
the dissolution of 2-naphthol in water at 283 to 368 K, of benzoic acid in water at 283 to 338 K, of salicylic acid in water
at 283 to 343 K, of camphor in water at 283 to 318 K, and of cinnamic acid in water at 283 to 318 K. Empirical correlations
are presented for the prediction of molecular diffusion coefficient over the entire range of temperatures studied, and they
are shown to predict the obtained data with very good accuracy. 相似文献