全文获取类型
收费全文 | 306027篇 |
免费 | 29142篇 |
国内免费 | 17609篇 |
专业分类
电工技术 | 24419篇 |
技术理论 | 10篇 |
综合类 | 34178篇 |
化学工业 | 32367篇 |
金属工艺 | 13028篇 |
机械仪表 | 24979篇 |
建筑科学 | 36420篇 |
矿业工程 | 12760篇 |
能源动力 | 12098篇 |
轻工业 | 20769篇 |
水利工程 | 13139篇 |
石油天然气 | 13859篇 |
武器工业 | 3787篇 |
无线电 | 19207篇 |
一般工业技术 | 33878篇 |
冶金工业 | 12244篇 |
原子能技术 | 4595篇 |
自动化技术 | 41041篇 |
出版年
2024年 | 1265篇 |
2023年 | 3675篇 |
2022年 | 7307篇 |
2021年 | 8588篇 |
2020年 | 9315篇 |
2019年 | 7874篇 |
2018年 | 7714篇 |
2017年 | 9616篇 |
2016年 | 11144篇 |
2015年 | 11695篇 |
2014年 | 19148篇 |
2013年 | 18770篇 |
2012年 | 23101篇 |
2011年 | 24498篇 |
2010年 | 18191篇 |
2009年 | 18682篇 |
2008年 | 17315篇 |
2007年 | 21137篇 |
2006年 | 18454篇 |
2005年 | 15474篇 |
2004年 | 12948篇 |
2003年 | 11078篇 |
2002年 | 9145篇 |
2001年 | 7555篇 |
2000年 | 6564篇 |
1999年 | 5567篇 |
1998年 | 4567篇 |
1997年 | 3920篇 |
1996年 | 3247篇 |
1995年 | 2812篇 |
1994年 | 2443篇 |
1993年 | 1790篇 |
1992年 | 1637篇 |
1991年 | 1175篇 |
1990年 | 991篇 |
1989年 | 909篇 |
1988年 | 702篇 |
1987年 | 437篇 |
1986年 | 385篇 |
1985年 | 271篇 |
1984年 | 309篇 |
1983年 | 265篇 |
1982年 | 231篇 |
1981年 | 140篇 |
1980年 | 115篇 |
1979年 | 94篇 |
1978年 | 59篇 |
1977年 | 56篇 |
1976年 | 54篇 |
1959年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
P. J. M. Sonnemans P. M. W. Krvers A. C. Brombacher P. C. van Beek J. E. A. Reinders 《Quality and Reliability Engineering International》2003,19(3):183-196
Often companies in the (petro‐) chemical industry claim that all possible countermeasures against potential accidents have been taken and therefore accidents are unforeseeable. In this paper we question this statement by analysing the pre‐warning signals (precursors) preceding a number of industrial accidents. 17 accidents that occurred in the (petro‐) chemical industry have been investigated by exploring FACTS, an accident database containing information about industrial accidents worldwide. This paper will demonstrate that the existence of precursor information could have been used to foresee and even prevent these accidents if a proper control action had been initiated. The accidents are analysed further, according to a control model, which was adapted from that of C. Argyris. It demonstrates the ineffectiveness of several elements of business process control loops and that the so‐called ‘double‐loop learning’ cycle is more important than the ‘single‐loop learning’ cycle if one considers safety improvement. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
92.
Microstructure evolution during metal forming processes 总被引:8,自引:0,他引:8
Recrystallization and grain growth evolutions during metal forming processes are considered. Coupling between the thermo-mechanical and microstructure processes is realized. Die forging of a rear-axle flange is simulated numerically on the base of the finite element method. Material parameters of the models are obtained experimentally. The influence of interpass and holding times on grain size distributions in the end product is shown. 相似文献
93.
William E Acree Jr Michael H Abraham 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(8):1441-1446
The contentions made in an earlier paper [J Chem Technol Biotechnol 80 : 133–137 (2005)] that the coefficients of the Abraham solvation equation do not provide meaningful information on the molecular properties of ionic liquid solvents is refuted. The objections noted in the earlier paper disappear when the solvation equation model is correctly applied to the experimental data. It is further shown that the coefficients of the Abraham solvation equations can be used to characterize ionic liquids and can be used to select solvents for the solubility of gaseous solutes. Copyright © 2006 Society of Chemical Industry 相似文献
94.
E.I.P. Volcke M. Loccufier P.A. Vanrolleghem E.J.L. Noldus 《Journal of Process Control》2006,16(10):1003-1012
This paper addresses the dynamics of a SHARON reactor, a promising technology for ammonium removal from concentrated wastewater streams. The contraction mapping theorem is used to determine which operating conditions of a SHARON reactor with pH-control result in a unique equilibrium state. However, this approach only identifies the case of very large dilution rates, in practice corresponding with complete biomass wash-out, i.e. with complete loss of biological activity. Practical operation of a SHARON reactor aims at reaching ammonium conversion to nitrite. To identify such interesting operating points, the equilibrium points are subsequently calculated directly in terms of input variables for a simplified SHARON reactor model. The stability of the obtained equilibrium points is assessed and the corresponding phase portraits are analyzed. The influence of slightly varying parameter and input values is investigated as well. 相似文献
95.
This paper deals with a new boundary element method for analysis of the quasistatic problems in coupled thermoelasticity. Through some mathematical manipulation of the Navier equation in elasticity, the heat conduction equation is transformed into a simpler form, similar to the uncoupled-type equation with the modified thermal conductivity which shows the coupling effects. This procedure enables us to treat the coupled thermoelastic problems as an uncoupled one, A few examples are computed by the proposed BEM, and the results obtained are compared with the analytical ones available in the literature, whereby the accuracy and versatility of the proposed method are demonstrated. 相似文献
96.
Takashi Ishikawa Sunao Sugimoto Masamichi Matsushima Yoichi Hayashi 《Composites Science and Technology》1995,55(4):349-363
Compression-after-impact (CAI) tests have been conducted for quasi-isotropic thick plates with 48 plies by using the NASA method and on plates with 32 plies by using the SACMA method. Specimens are made of CF/PEEK (APC-2) and conventional CF/epoxy for the NASA plates and CF/epoxy for the SACMA plates. In the NASA CAI tests, the sequence of delamination buckling and its propagation is clearly revealed through various experimental techniques. One major technique is moiré topography, and the other is thermo-mechanical stress analysis with a high-accuracy infrared sensor. The arrest of delamination propagation just before catastrophic failure due to high fracture toughness is clearly captured by the moiré camera. This behavior provides good CAI values of CF/PEEK. The initial buckling properties of the delaminated region by the impact are then extensively discussed. Numerical predictions of initial buckling stress have been obtained by modelled geometry of the delaminated region simplified from its precise structure clarified by ultrasonic C-scanning. They agree fairly well with the experimental results. The in-plane stress distribution in the delaminated region before initial buckling is measured by an infrared stress graphic system. This compared favorably with finite element predictions. Two types of symmetric buckling modes with respect to the central plate surface, twin and single peak ones, are experimentally captured. 相似文献
97.
高放废液化学成分分析 总被引:3,自引:0,他引:3
概述了高放废液中25种阳离子、5种阴离子以及总蒸残物、总氧化物、密度和游离酸的分析方法。对核燃料后处理高放废液进行取样分析,其主要化学成分采用两种以上不同原理的方法作对比测定,结果相互符合情况良好,为高放废液处理处置研究设计,提供了完整、准确的基础数据。 相似文献
98.
Periklis E. Ergatis Panagiotis G. Massouros Georgia C. Athanasouli George P. Massouros 《国际能源研究杂志》2003,27(9):795-811
A time‐dependent coefficient of heat transfer is proposed for the computation of thermal power required, so that a room temperature reaches a desired value within a given time. A mathematical formulation of the room heating transient phenomenon is constructed in a dimensionless form. Using an integral approximate solution an analytical expression for this coefficient is provided and it is verified by diagrams adopted by DIN 4701. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
99.
Solving regularized least squares with qualitatively controlled adaptive cross‐approximated matrices
The adaptive cross‐approximation (ACA) technique is applied to accelerating an inverse‐problem solver that estimates charge distribution on a dielectric spacer. The ACA generates an approximated system‐matrix that enables us to carry out high‐speed inverse calculation. We designed an approximation procedure based on ACA with some additional concepts, that is, (a) partitioning of matrix based on algebraic information, (b) approximation quality control based on matrix norms, and so on. The tested solver (LSQR for regularized least squares) with ACA demonstrates about 10 times faster performance than that without ACA. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(3): 10–18, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20326 相似文献
100.