全文获取类型
收费全文 | 4132篇 |
免费 | 190篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 51篇 |
综合类 | 5篇 |
化学工业 | 1126篇 |
金属工艺 | 54篇 |
机械仪表 | 83篇 |
建筑科学 | 243篇 |
矿业工程 | 63篇 |
能源动力 | 109篇 |
轻工业 | 446篇 |
水利工程 | 73篇 |
石油天然气 | 5篇 |
无线电 | 346篇 |
一般工业技术 | 597篇 |
冶金工业 | 374篇 |
原子能技术 | 20篇 |
自动化技术 | 735篇 |
出版年
2023年 | 27篇 |
2022年 | 74篇 |
2021年 | 131篇 |
2020年 | 65篇 |
2019年 | 76篇 |
2018年 | 97篇 |
2017年 | 77篇 |
2016年 | 144篇 |
2015年 | 114篇 |
2014年 | 161篇 |
2013年 | 215篇 |
2012年 | 243篇 |
2011年 | 244篇 |
2010年 | 197篇 |
2009年 | 203篇 |
2008年 | 202篇 |
2007年 | 170篇 |
2006年 | 199篇 |
2005年 | 124篇 |
2004年 | 86篇 |
2003年 | 104篇 |
2002年 | 105篇 |
2001年 | 58篇 |
2000年 | 56篇 |
1999年 | 69篇 |
1998年 | 62篇 |
1997年 | 50篇 |
1996年 | 42篇 |
1995年 | 43篇 |
1994年 | 55篇 |
1993年 | 44篇 |
1992年 | 36篇 |
1991年 | 41篇 |
1990年 | 38篇 |
1989年 | 36篇 |
1988年 | 27篇 |
1986年 | 26篇 |
1985年 | 33篇 |
1984年 | 40篇 |
1983年 | 27篇 |
1982年 | 38篇 |
1981年 | 41篇 |
1980年 | 27篇 |
1979年 | 33篇 |
1978年 | 28篇 |
1977年 | 28篇 |
1976年 | 32篇 |
1975年 | 33篇 |
1974年 | 32篇 |
1970年 | 28篇 |
排序方式: 共有4330条查询结果,搜索用时 296 毫秒
31.
32.
This paper deals with the non-linear analysis of multilayered axially compressed plates in the static elastic conservative cases. A finite element model based on a Reissner-Mindlin theory involving von Kármán nonlinearity is developed. Results related to the classical Kirchhoff plate approximations are obtained via application of a penalty technique to the shear correction factor. The numerical investigations have concerned the large deflections and postbuckling behaviour of symmetrically and non-symmetrically anisotropic flat panels. The main conclusions are: (1) the non-linear effects very much depend on lay-up and boundary conditions, moreover for the asymmetric laminated long plates the snapping-type instability occurs; (2) the shear deformation effects are very much subordinate to both multilayered lay-up and load levels, furthermore they are greater in the large deflections field; (3) it has been observed that in the neighbourhood of a singularity (of buckling point type) of the tangent stiffness matrix, the use of an arc-length type algorithm could lead to a new buckled path and that happens without employing an appropriate turning bifurcation algorithm with an accompanying eigenvalues calculation, but via a non-convergent iteration in the loadstep. 相似文献
33.
Howard R. Moskowitz Michele Reisner Barbara Itty Rachel Katz Bert Krieger 《Food quality and preference》2006,17(7-8):536-551
Innovation is often left to insight and serendipity. A lot of what researchers call innovation is actually a process by which one can make the individual consumer or practitioner more ‘creative’. Although it is important to work with the creative individual in hopes of coming up with the better ‘idea’ and new product/service opportunity, an equally valid albeit novel and counterintuitive approach systematizes creativity in a ‘research-driven machine’. This paper presents an approach to the systematization, based upon the point of view that creativity and innovation comprise the recombination of components into new blends. Given this point of view, to then spur innovation requires a systematic database that the user can access, with tools to help manipulate that database. The paper shows how such a database can be constructed and then used to create a novel product. The approach provides a general framework for the sensory professional to become more involved in the early stages of product development, where the focus is on the conceptual aspects of food features rather than on their physical manifestations in actual products. 相似文献
34.
35.
Pictures were shown with superimposed word distractors of high and low frequency. Low-frequency distractors produced greater interference on picture naming than did high-frequency distractors. This distractor frequency effect was not affected by manipulations that facilitated or hindered distractor recognition. Interference was reduced for distractors that were read aloud several times prior to being shown in the picture-naming task. Together these findings suggest that the distractor frequency effect has its locus at some stage of lexical access for production. Other findings further constrain hypotheses about which level of speech production is involved in the effect. The distractor frequency effect has implications for models of lexical processing in speaking as well as for accounts of picture-word interference and the frequency effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
36.
37.
38.
In connection with the analysis and the development of failure concepts in fracture mechanics for quasistatic loaded components and elastic-plastic behaviour of the material, tests are also carried out with welded and/or complex shaped specimens or structures. Thereby the difficulty arises of generating reproducible flaws in the form of fatigue precracks in definite positions in the components, respectively in the welded joint. It is reported exemplarily about experiments on different CT25 and CCT specimens and on a pressure vessel which contained a fatigue pre-crack, a 0.2 mm saw cut or notches with notch root radius ≤ ≥ 0.1 mm as flaws. The comparison of the results with regard to J-integral at initiation of stable crack, Ji, and JR curves shows that under certain conditions the 0.2 mm saw cut (notch root radius ≤ ≤ 0.02 mm) is a useful alternative, if reproducible generation of a fatigue pre-crack will not be successful or too expensive. The tests were carried out on StE 460 and on a welded joint of this steel at 25 ± 2°C. 相似文献
39.
S. Salar Behzadi Silvester Ölzant Reinhard Länger Christian Koban Frank M. Unger Helmut Viernstein 《European Food Research and Technology》2006,223(2):238-245
Inversion of sucrose is a stability problem particularly of candies with acidic taste that contain sucrose and small amounts of organic acids such as citric acid, since the free d-fructose produced by hydrolysis is hygroscopic. The following possibilities were investigated for preventing the hydrolysis of sucrose in tablets containing sucrose and citric acid: Adding various amounts of tri-sodium citrate to the formulation to neutralize the citric acid, (Hot) melt coating of citric acid and tri-sodium citrate with a vegetable fat at different coating ratios, variation of the ratio of coated citric acid and tri-sodium citrate in formulations, and compressing the formulations with different compression forces. After tablet processing and storage of tablets, the concentration of d-fructose was determined on the basis of enzymatic reactions. A response surface central composite design was used. The above-mentioned variations were chosen as independent variables and the amount of d-fructose was chosen as response variable. The lowest rates of inversion could be achieved by increasing the content of tri-sodium citrate and the ratio of coating material and decreasing the ratio of coated citric acid and tri-sodium citrate in the tablet formulations. The compression force had no significant effect on the inversion of sucrose. 相似文献
40.