全文获取类型
收费全文 | 13992篇 |
免费 | 1157篇 |
国内免费 | 583篇 |
专业分类
电工技术 | 750篇 |
技术理论 | 1篇 |
综合类 | 933篇 |
化学工业 | 2616篇 |
金属工艺 | 741篇 |
机械仪表 | 881篇 |
建筑科学 | 926篇 |
矿业工程 | 378篇 |
能源动力 | 394篇 |
轻工业 | 964篇 |
水利工程 | 251篇 |
石油天然气 | 740篇 |
武器工业 | 96篇 |
无线电 | 1565篇 |
一般工业技术 | 1919篇 |
冶金工业 | 655篇 |
原子能技术 | 165篇 |
自动化技术 | 1757篇 |
出版年
2024年 | 60篇 |
2023年 | 247篇 |
2022年 | 353篇 |
2021年 | 539篇 |
2020年 | 453篇 |
2019年 | 347篇 |
2018年 | 417篇 |
2017年 | 469篇 |
2016年 | 382篇 |
2015年 | 522篇 |
2014年 | 675篇 |
2013年 | 857篇 |
2012年 | 819篇 |
2011年 | 829篇 |
2010年 | 800篇 |
2009年 | 712篇 |
2008年 | 673篇 |
2007年 | 733篇 |
2006年 | 730篇 |
2005年 | 601篇 |
2004年 | 422篇 |
2003年 | 476篇 |
2002年 | 555篇 |
2001年 | 436篇 |
2000年 | 369篇 |
1999年 | 383篇 |
1998年 | 334篇 |
1997年 | 295篇 |
1996年 | 253篇 |
1995年 | 201篇 |
1994年 | 168篇 |
1993年 | 118篇 |
1992年 | 105篇 |
1991年 | 86篇 |
1990年 | 68篇 |
1989年 | 49篇 |
1988年 | 42篇 |
1987年 | 25篇 |
1986年 | 32篇 |
1985年 | 10篇 |
1984年 | 16篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 8篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Polyvinyl alcohol (PVA) films containing 10% w/w of a model drug, sulphathiazole, were cast from aqueous solutions and subjected to heat treatment at specific temperatures for known periods of time. Heat treatment at temperatures above the Tg of the PVA films slowed down the rate of drug release from the films. Increasing the temperature of heat treatment from 120°C to 160°C further decreased the rate of drug release. On the other hand, if the heat treatment were conducted at a temperature below the Tg e.g. at 80°C, there were insignificant differences between the release profile of sulphathiazole from heat-treated films and that from untreated films. The duration of heat treatment affected the rate of drug release to a smaller extent compared to the temperature of heat treatment. These results correlated with the heat induced changes in the morphology of, and in the extent of water uptake by the PVA films. 相似文献
62.
63.
公共娱乐场所消防安全现状及对策 总被引:1,自引:0,他引:1
卿婉丽 《消防技术与产品信息》2005,(5):22-23
从消防安全管理的角度,论述了公共娱乐场所消防安全存在的主要问题和如何进一步加强公共娱乐场所的消防安全工作 相似文献
64.
本文介绍了一种利用数字信号处理器TMS320C25用作雷达数据实时处理,利用图形处理器TMS34010用作雷达视频图象处理,完成雷达视频图象彩色显示的雷达终端。 相似文献
65.
根据南方风沙化地自然及气候的特点,提出并讨论了在风沙化土地区营造防风固沙林;建立沙地果业基地;发展沙区畜牧水产业;搞好沙地蔬菜生产;完善农防林体系建设,发展沙区工业等开发利用模式。 相似文献
66.
67.
68.
采用真空蒸发的方法交替沉积Ag和TCNQ分子制备了Ag TCNQ金属 有机络合物薄膜 ,并研究了多种外加电压激发下膜的电阻转变特性。发现在转变过程中存在着一种能量效应 ,即当外电压超过某一阈值后 ,完成转变的能量不变。对此现象的可能解释是薄膜内分子在一定的外部电场能量诱导下发生重排 ,致使电导率发生跃变 相似文献
69.
Wan Fokkink Rob van Glabbeek Paulien de Wind 《Electronic Notes in Theoretical Computer Science》2006,156(1):97
We present congruence formats for η- and rooted η-bisimulation equivalence. These formats are derived using a method for decomposing modal formulas in process algebra. To decide whether a process algebra term satisfies a modal formula, one can check whether its subterms satisfy formulas that are obtained by decomposing the original formula. The decomposition uses the structural operational semantics that underlies the process algebra. 相似文献
70.
Desirable flavor qualities of cocoa are dependent on how the cocoa beans are fermented, dried, and roasted. During fermentation and drying, polyphenols such as leucocyanidin and apecatechin are oxidized by polyphenols oxidase to form o-quinone, which later react nonenzymatically with a hydroquinone in a condensation reaction to form browning products and moisture. The objective of this article is to model the cocoa beans drying together with the browning reaction. A Luikov drying model for the moisture and a simple Fick's law diffusion model combined with first-order reactions for both the enzymatic oxidation and nonenzymatic condensation reactions were constructed. Both models were used to identify moisture diffusivity coefficient and total polyphenols diffusivity in cocoa beans from experimental drying and polyphenols degradation data and published kinetic data of the reactions. The theoretical drying model fitted the experimental cocoa bean drying curves with low mean square of residuals. The polyphenols diffusion and reaction model also fitted the experimental polyphenols degradation curves with minimum mean residual squares. The rate of polyphenols degradation in the cocoa beans increases at higher temperature and higher relative humidity. This is because the increasing reaction rate of polyphenols oxidation reaction as well as higher moisture diffusion at higher relative humidity and temperature. The effective moisture diffusivity in cocoa beans is estimated to be between 8.194 × 10-9 and 8.542 × 10-9 m2·s-1, which is of the same order of magnitude as published data. The effective total polyphenols diffusivity is estimated to be between 8.333 × 10-12 to 1.000 × 10-11 m2·s-1 with minimum mean residual squares. It is three orders of magnitude less than the estimated moisture diffusivity because of the larger polyphenols molecules. The estimated polyphenols diffusivity is very close to those published in the literature for sorption and ultrafiltration processes. 相似文献