全文获取类型
收费全文 | 47284篇 |
免费 | 1945篇 |
国内免费 | 1918篇 |
专业分类
电工技术 | 1644篇 |
技术理论 | 18篇 |
综合类 | 5047篇 |
化学工业 | 5778篇 |
金属工艺 | 1331篇 |
机械仪表 | 2277篇 |
建筑科学 | 7755篇 |
矿业工程 | 3034篇 |
能源动力 | 1581篇 |
轻工业 | 3667篇 |
水利工程 | 2136篇 |
石油天然气 | 3904篇 |
武器工业 | 263篇 |
无线电 | 1696篇 |
一般工业技术 | 2324篇 |
冶金工业 | 4264篇 |
原子能技术 | 151篇 |
自动化技术 | 4277篇 |
出版年
2024年 | 89篇 |
2023年 | 296篇 |
2022年 | 794篇 |
2021年 | 1010篇 |
2020年 | 990篇 |
2019年 | 648篇 |
2018年 | 589篇 |
2017年 | 821篇 |
2016年 | 1038篇 |
2015年 | 1109篇 |
2014年 | 2672篇 |
2013年 | 2359篇 |
2012年 | 2944篇 |
2011年 | 3522篇 |
2010年 | 3018篇 |
2009年 | 2894篇 |
2008年 | 2492篇 |
2007年 | 3271篇 |
2006年 | 3370篇 |
2005年 | 3078篇 |
2004年 | 2634篇 |
2003年 | 2376篇 |
2002年 | 1925篇 |
2001年 | 1681篇 |
2000年 | 1427篇 |
1999年 | 988篇 |
1998年 | 725篇 |
1997年 | 516篇 |
1996年 | 392篇 |
1995年 | 286篇 |
1994年 | 223篇 |
1993年 | 146篇 |
1992年 | 134篇 |
1991年 | 80篇 |
1990年 | 69篇 |
1989年 | 64篇 |
1988年 | 37篇 |
1987年 | 29篇 |
1986年 | 38篇 |
1985年 | 44篇 |
1984年 | 29篇 |
1983年 | 18篇 |
1982年 | 18篇 |
1981年 | 21篇 |
1980年 | 14篇 |
1979年 | 14篇 |
1965年 | 19篇 |
1964年 | 19篇 |
1956年 | 12篇 |
1955年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
The compaction properties of an investigational drug are studied by the use of a compaction simulator. The effects of punch velocity over the range of 30-640 mm-1 on the compaction properties of the pure drug and a variety of formulas incorporating a high dose of the active compound have been investigated. The data were analyzed by applying the Heckel equation. The pure drug was found to have a high yield pressure at a relatively low punch velocity of 31 mm-1. As the punch velocity was increased there was a decrease in crushing strength, primarily as a result of increasing yield pressure. These findings indicate that the pure drug predominantly consolidated by fragmentation and elastic deformation, with a slow plastically deforming component. The information obtained on the consolidation mechanism of the pure drug and, subsequently, on model formulas were instrumental in the design and selection of a robust formula and granulation process. The advantages of conducting dosage form design and characterization studies during the early phase of tablet formulation using means such as a compaction simulator are emphasized in this investigation. 相似文献
122.
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
123.
石油钻井用泥浆泵的新发展 总被引:1,自引:1,他引:0
泥浆泵已发展到大功率、大排量、高压力。为适应现代钻井技术的发展,钻井设备制造商开发出了性能更好,体积更小,质量更轻的泥浆泵,以满足钻井承包商适应各种钻井工况的需要。文章简要介绍了近几年国内外新出现的几种泥浆泵。 相似文献
124.
洁净型煤技术开发研制 总被引:4,自引:0,他引:4
通过对洁净型煤技术的介绍,并对型煤质量及燃烧测试分析,认为洁净型煤技术是一种煤的高效洁净燃烧、改善环境空气质量及节约能源的有效技术。 相似文献
125.
中国第三代移动通信技术发展概况与战略建议(上) 总被引:1,自引:0,他引:1
本文第一部分重点介绍了中国移动通信的现状以及国际3G的现状,并简单介绍了3G通信存在的几个问题。 相似文献
126.
Evan E. Anderson 《Information Systems》1988,13(4):327-333
Many organizations, best illustrated by libraries, have access to hundreds of databases possessing varying degrees of complimentary and overlapping records. While users may receive positive marginal benefits from data duplications, all databases and their services cannot be supported because of resource limitations. This paper attempts to conceptualize the problem of database collection in an environment of multiple databases, with differential content and performance characteristics, diverse users, and limited resources. It defines the database collection problem as a constrained zero-one integer programming problem and solves for the optimal combination or union of databases. Several extensions are shown, where special conditions are imposed on the relationships between databases and/or their availability. 相似文献
127.
128.
Melamed Barbara G.; Matthews Karen A.; Routh Donald K.; Stabler Brian 《Canadian Metallurgical Quarterly》1986,5(3):181
This article introduces the current issue of Health Psychology. The call for early intervention to prevent adulthood health problems and the need to consider each period of children's lives within its developmental perspective are the main emphases in this special issue of the journal. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
129.
我国锦纶帘子布市场发展态势及对策 总被引:2,自引:0,他引:2
通过对我国当前帘布市场态势的分析和今后三年的需求预测,探讨了锦纶帘线的生产发展对策。认为“八五”期间,我国锦纶帘布市场将呈现供大于求的局面,在一段时期内,锦纶帘布仍将是主要的橡胶骨架材料,其占比例为70%左右。预计1993~1995年,锦纶橡胶骨架材料的市场需求量分别为9.16,10.37.11.69万t。 相似文献
130.