全文获取类型
收费全文 | 22747篇 |
免费 | 1053篇 |
国内免费 | 575篇 |
专业分类
电工技术 | 750篇 |
技术理论 | 7篇 |
综合类 | 2155篇 |
化学工业 | 3228篇 |
金属工艺 | 707篇 |
机械仪表 | 1298篇 |
建筑科学 | 3276篇 |
矿业工程 | 896篇 |
能源动力 | 864篇 |
轻工业 | 1928篇 |
水利工程 | 681篇 |
石油天然气 | 1257篇 |
武器工业 | 203篇 |
无线电 | 843篇 |
一般工业技术 | 1878篇 |
冶金工业 | 2151篇 |
原子能技术 | 294篇 |
自动化技术 | 1959篇 |
出版年
2024年 | 83篇 |
2023年 | 241篇 |
2022年 | 429篇 |
2021年 | 538篇 |
2020年 | 660篇 |
2019年 | 425篇 |
2018年 | 362篇 |
2017年 | 502篇 |
2016年 | 633篇 |
2015年 | 728篇 |
2014年 | 1714篇 |
2013年 | 1333篇 |
2012年 | 1591篇 |
2011年 | 1800篇 |
2010年 | 1385篇 |
2009年 | 1387篇 |
2008年 | 1172篇 |
2007年 | 1384篇 |
2006年 | 1387篇 |
2005年 | 1076篇 |
2004年 | 925篇 |
2003年 | 844篇 |
2002年 | 691篇 |
2001年 | 561篇 |
2000年 | 454篇 |
1999年 | 339篇 |
1998年 | 276篇 |
1997年 | 184篇 |
1996年 | 178篇 |
1995年 | 129篇 |
1994年 | 92篇 |
1993年 | 83篇 |
1992年 | 65篇 |
1991年 | 43篇 |
1990年 | 75篇 |
1989年 | 46篇 |
1988年 | 52篇 |
1987年 | 33篇 |
1986年 | 30篇 |
1985年 | 20篇 |
1984年 | 46篇 |
1983年 | 20篇 |
1982年 | 18篇 |
1966年 | 24篇 |
1964年 | 18篇 |
1963年 | 18篇 |
1959年 | 29篇 |
1957年 | 16篇 |
1955年 | 21篇 |
1954年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
质量成本是指企业为保证产品质量而支出的一切费用,以及产品质量未达到规定的标准而造成的一切损失的总和。开展质量成本研究工作是企业深化质量管理和成本管理的一条有效途径。 相似文献
42.
加氢反应器内构件—急冷箱的试验研究 总被引:2,自引:0,他引:2
急冷箱是加氢反应器的重要内件。洛阳石化工程公司设备研究所在认真分析UOP急冷箱的基础上,对其结构进行了改进,开发出了新型急冷箱(已获专利)。经过流体力学、传质、传热性能对比试验、分析,新型急冷箱结构性能优良。 相似文献
43.
曙光油田超稠油井套管损坏的机理和防治 总被引:8,自引:0,他引:8
超稠油特殊的油藏特点决定了其生产周期短、注汽频繁、出砂、汽窜、超覆现象严重,以及套管质量等因素的影响,套管损坏较为严重。对曙光油田超稠油井套管损坏的规律和机理进行了研究,并从钻井和完井工艺的完善、套管钢级和射孔工艺的选择、采油生产参数的确定、注汽管柱隔热效果的提高、防治砂工艺等方面,对套管损坏提出了预防措施和对策。并对套管损坏井制定了修复再利用方案。 相似文献
44.
Richard F. D.; Bond Charles F. Jr.; Stokes-Zoota Juli J. 《Canadian Metallurgical Quarterly》2003,7(4):331
This article compiles results from a century of social psychological research, more than 25,000 studies of 8 million people. A large number of social psychological conclusions are listed alongside meta-analytic information about the magnitude and variability of the corresponding effects. References to 322 meta-analyses of social psychological phenomena are presented, as well as statistical effect-size summaries. Analyses reveal that social psychological effects typically yield a value of r equal to .21 and that, in the typical research literature, effects vary from study to study in ways that produce a standard deviation in r of .15. Uses, limitations, and implications of this large-scale compilation are noted. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
45.
Gülü Insel Derin Orhon Peter A Vanrolleghem 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(4):437-445
Hydrolysis mechanism plays a dominant role in the delicate balance of electron donor/electron acceptor ratios in BNR and EBPR systems as an important carbon source. In this study, the surface‐saturation‐type hydrolysis kinetics was investigated based on respirometric measurements, within the context of the theoretical and the practical identifiability of mathematical models. The identifiable parameters of a selected model were derived from respirograms. In addition, the information from the experiments was evaluated on the basis of Optimal Experimental Design (OED) methodology for different initial conditions of the batch respirometric experiment. © 2003 Society of Chemical Industry 相似文献
46.
FLOW OF NEWTONIAN FLUIDS THROUGH SINUSOID ALLY CONSTRICTED TUBES. NUMERICAL AND EXPERIMENTAL RESULTS
J. A. Deiber Mb. Peirotti R. A. Bortolozzi R. J. Durelli 《Chemical Engineering Communications》1992,117(1):241-262
Numerical and experimental predictions of pressure drops in the flow of Newtonian fluids through sinusoidally constricted tubes (SCT) are carried out. The numerical evaluations analyzed in this work are obtained from the following methods: Geometric Iteration (GJM), Geometric Iteration with First and Second Upwinds (GIM1, GIM2), Successive Over Relaxation by Line (SORBLM), Global Galerkin Spectral Method (GGSM), Collocation (CM) and Dufort-Frankel (DFM). The GIM1, GIM2 and SORBLM are applied to SCT and explained in this work. The other methods have been previously reported in the literature with the same purpose. Experiments are accomplished for constrictions of approximately 40,60 and 80% of the average tube diameter and results compare well with numerical predictions of the steady flow. It is concluded that special attention should be given to evaluations of the friction factor ƒ for Reynolds numbers Re between the onsets of flow separation and turbulence due to flow instability. Finally, the SCT as a model for porous media (PM) is discussed. 相似文献
47.
Ellen Spolsky 《Computers and the Humanities》1993,27(5-6):323-329
Olsen is right to note what can be done with a good theory and the right machine. His particular theory, however, is not transferable to literary studies. If we need a new model, I would suggest that cognitive science can provide a few interesting ones. I have begun to do some work based on David Marr's VISION, in which he hypothesizes two levels of processing within the visual module. My speculation has been on the parallel existence of distinguishable levels of conceptual or language organization which would correspond to the viewer and object centered perspectives Marr describes for vision. I propose to explore the possibility that we may find here the model for the existence of stylistic individualism within overarching historical stylistic generalizations, and even more, that this may be what feminists are searching for when they try to resist being coopted by the masculine language of objectivity.
Ellen Spolsky teaches English literature and literary theory and is the Director of the Lechter Institute for Literary Research at Bar-Ilan University, Israel. Her latest book is Gaps in Nature: Literary Interpretation and the Modular Mind(SUNY Press, 1993). 相似文献
48.
火炸药包装用纸桶的研究 总被引:1,自引:1,他引:0
简述了我国火炸药包装的现状。介绍了火炸药用纸桶包装的研究情况,其中,较详细叙述了纸桶的力学性能、运输和使用试验结果,分析了纸桶包装火炸药的社会、经济效益。 相似文献
49.
实证分析:上市公司资本结构的影响因素 总被引:13,自引:0,他引:13
在国内外相关研究的基础上,利用我国资本市场的公开数据,对上市公司资本结构的影响因素进行实证研究,得出了若干重要结论。 相似文献
50.
Reviews the book, Basic Processes in Reading Visual Word Recognition by Derek Besner and Glyn W. Humphreys (see record 1990-99017-000). While there has been an increase in the amount of work on many different aspects of reading, as Besner and Humphreys point out in the overview to their book, the vast majority of the research on the topic of reading in the past twenty years has been concerned with the processes involved in word recognition. For this reason, Besner and Humphreys have attempted to bring together studies on topics which are both relevant to current debates in the field of word recognition, and which are likely to be important for future developments in the field. They have compiled an edited volume consisting of their overview and eight additional chapters. The editors have attempted to span the continuum of processes involved in word recognition and thus have included chapters which cover topics ranging from the visual analysis of words, to those on the influence of semantic factors on word recognition. The authors of these chapters comprise an impressive list of researchers in the field of word recognition, with the majority of chapters being authored by leading researchers on the topic. Given the stature of the authors and the range of topics covered, in theory this volume should provide a very thorough overview of current theory and research on reading. There is no question that each of the chapters is interesting and important in its own right. However, in practice the volume as a whole fell somewhat short of my expectations. The different tacts taken by different authors has resulted in a very uneven coverage of the current debates in the field. Notwithstanding these criticisms, I am sure that the majority of researchers in this field will consider this volume to be an important contribution. The book would provide a very useful addition to graduate courses in cognitive sciences and as a supplemental text for an undergraduate course on the psychology of reading. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献