全文获取类型
收费全文 | 2924篇 |
免费 | 169篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 40篇 |
综合类 | 2篇 |
化学工业 | 723篇 |
金属工艺 | 69篇 |
机械仪表 | 65篇 |
建筑科学 | 96篇 |
矿业工程 | 5篇 |
能源动力 | 80篇 |
轻工业 | 313篇 |
水利工程 | 8篇 |
石油天然气 | 20篇 |
无线电 | 220篇 |
一般工业技术 | 524篇 |
冶金工业 | 403篇 |
原子能技术 | 20篇 |
自动化技术 | 508篇 |
出版年
2023年 | 26篇 |
2022年 | 82篇 |
2021年 | 96篇 |
2020年 | 53篇 |
2019年 | 62篇 |
2018年 | 91篇 |
2017年 | 86篇 |
2016年 | 112篇 |
2015年 | 71篇 |
2014年 | 109篇 |
2013年 | 205篇 |
2012年 | 163篇 |
2011年 | 205篇 |
2010年 | 121篇 |
2009年 | 164篇 |
2008年 | 151篇 |
2007年 | 140篇 |
2006年 | 119篇 |
2005年 | 85篇 |
2004年 | 84篇 |
2003年 | 87篇 |
2002年 | 56篇 |
2001年 | 41篇 |
2000年 | 45篇 |
1999年 | 43篇 |
1998年 | 106篇 |
1997年 | 64篇 |
1996年 | 62篇 |
1995年 | 38篇 |
1994年 | 37篇 |
1993年 | 24篇 |
1992年 | 20篇 |
1991年 | 15篇 |
1990年 | 17篇 |
1989年 | 18篇 |
1988年 | 10篇 |
1987年 | 19篇 |
1986年 | 11篇 |
1985年 | 19篇 |
1984年 | 14篇 |
1983年 | 21篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 5篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 11篇 |
1976年 | 18篇 |
1975年 | 5篇 |
1973年 | 6篇 |
排序方式: 共有3096条查询结果,搜索用时 31 毫秒
11.
Robert H. Doremus Denis Murphy Narottam P. Bansal William A. Lanford Chandra Burman 《Journal of Materials Science》1985,20(12):4445-4453
When liquid water contacts a zirconium-barium-lanthanum fluoride glass, at least three different processes occur. Barium and zirconium fluoride dissolve into the water, water penetrates into the glass, and zirconium fluoride crystals grow on the glass surface, in static solution. The rate of dissolution, as measured by solution analysis, is possibly controlled by diffusion in the solid surface; surface blockage and surface reactions are other possible kinetic steps involved. Diffusion in solution is not the controlling mechanism. Hydrogen profiles in the glass surface suggest that the penetration rate of water into the glass is controlled by diffusion and a surface reaction. 相似文献
12.
Collage grammars are context-free devices which generate picture languages consisting of collages—sets of parts, where a part is a set of points in a given space. In order to show that certain collage languages cannot be generated, the well-known pumping technique turns out to be rather useless. To circumvent this difficulty, other necessary criteria for context-freeness are established in this paper. Roughly speaking, these criteria reveal that (1) the collages in a context-free collage language can be deflated stepwise in such a manner that the difference between subsequent collages in the resulting chain is small and (2) the volume of parts can grow or shrink only exponentially. 相似文献
13.
Bandura Albert; O'Leary Ann; Taylor C. Barr; Gauthier Janel; Gossard Denis 《Canadian Metallurgical Quarterly》1987,53(3):563
In this experiment, we tested for opioid and nonopioid mechanisms of pain control through cognitive means and the relation of opioid involvement to perceived coping efficacy. Subjects were taught cognitive methods of pain control, were administered a placebo, or received no intervention. Their pain tolerance was then measured at periodic intervals after they were administered either a saline solution or naloxone, an opiate antagonist that blocks the effects of endogenous opiates. Training in cognitive control strengthened perceived self-efficacy both to withstand and to reduce pain; placebo medication enhanced perceived efficacy to withstand pain but not reductive efficacy; and neither form of perceived self-efficacy changed without any intervention. Regardless of condition, the stronger the perceived self-efficacy to withstand pain, the longer subjects endured mounting pain stimulation. The findings provide evidence that attenuation of the impact of pain stimulation through cognitive control is mediated by both opioid and nonopioid mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
14.
Myers Mark G.; MacPherson Laura; McCarthy Denis M.; Brown Sandra A. 《Canadian Metallurgical Quarterly》2003,15(2):163
The goal of the present studies was to construct and validate a short form of the 50-item Smoking Consequences Questionnaire (SCQ; T. H. Brandon & T. B. Baker, 1991), a measure of smoking outcome expectancies. In Study 1, a 21-item short form (S-SCQ) was derived from a sample of 107 young adults previously treated for substance abuse. In Study 2, the measure was cross-validated on 125 adolescents in treatment for substance abuse. Confirmatory factor analyses revealed good model fit and factorial invariance for the 4 S-SCQ subscales across both samples. Validation analyses on each sample found that subscale scores generally correlated significantly with smoking-related variables. The present studies provide initial evidence for the utility of the S-SCQ when used with young adults and adolescents. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
15.
Denis Rodrigue 《加拿大化工杂志》2002,80(2):289-292
Recently, the author (Rodrigue, 2001 a, b) proposed a generalized correlation for the steady rise of gas bubbles in uncontaminated viscous Newtonian fluids of infinite extent. It is the purpose of this note to show that this model can be modified for inelastic non‐Newtonian power‐law fluids. Using data taken from six different studies, it is shown that the modified model can predict quite nicely the bubble velocity for these non‐Newtonian inelastic fluids. 相似文献
16.
MM Simon P Pavlik A Hartig M Binder H Ruis WJ Cook CL Denis B Schanz 《Canadian Metallurgical Quarterly》1995,249(3):289-296
We examined the hypoxic tolerance phenomenon in vitro. Brief exposure to hypoxia induced the production of basic fibroblast growth factor (bFGF) mRNA and protein in rat cortical neurons and protected them from hypoxic injury. Cortical neurons were cultured from 18th-day rat embryos in a serum-free medium and subjected to brief (4 h) and/or prolonged (24 h) hypoxia. Neuronal damage was assessed by quantifying lactate dehydrogenase (LDH) activity in the medium. After brief hypoxia, LDH release was identical to that of the controls, whereas prolonged hypoxia caused a significant increase in LDH release, indicating neuronal death. However, if brief hypoxia was applied 2 days prior to the prolonged hypoxia, no increase in LDH release was observed. The bFGF mRNA expression was assessed with Northern blot and protein immunoreactivity with Western blot analysis. The brief period of hypoxia caused a 2.5-fold increase in bFGF mRNA and considerable bFGF protein expression 1 day later, but prolonged hypoxia caused increase in the expression of bFGF mRNA at 2 days and no protein expression until 3 days after the start of the hypoxia. When cells were subjected to prolonged hypoxia 2 days after brief hypoxia, however, no increase in bFGF mRNA was observed, while bFGF protein was expressed continuously. We also observed that exogenously applied bFGF reduced neuronal injury produced by prolonged hypoxia. The results obtained with this model suggest that brief hypoxia induces bFGF protein and thus tolerance to subsequent lethal hypoxia. Basic FGF might play a role as a tolerance-associated factor in this process. Thus, an in vitro model is useful for assessing the response of cortical neurons to hypoxic stress and for researching new factors related to ischemic tolerance. 相似文献
17.
This paper presents a dynamic integration algorithm to triangulate a surface from multiple range views. This integration technique is based on the reparameterization of the canonic subsets of the Venn diagram of the set of range views. We compute a model based onN views from a model based onN–1 views by processing only the surface segments visible in theN
th view. An experimental result shows that the proposed integration algorithm can process complex multipart objects containing holes. 相似文献
18.
Bafleur M. Vidal M. Puig Buxo J. Givelin Ph. Macary V. Sarrabayrouse G. 《Analog Integrated Circuits and Signal Processing》1995,8(3):219-231
To answer to the need of a cost effective smart power technology, an original design methodology that permits implementing latch-up free smart power circuits on a very simple CMOS/DMOS technology is proposed. The basic concept used to this purpose is letting float the wells of the MOS transistors most susceptible to initiate latch-up. The efficiency of the design methodology is experimentally shown. 相似文献
19.
20.