全文获取类型
收费全文 | 4741篇 |
免费 | 470篇 |
国内免费 | 214篇 |
专业分类
电工技术 | 345篇 |
综合类 | 249篇 |
化学工业 | 852篇 |
金属工艺 | 204篇 |
机械仪表 | 313篇 |
建筑科学 | 323篇 |
矿业工程 | 97篇 |
能源动力 | 309篇 |
轻工业 | 529篇 |
水利工程 | 86篇 |
石油天然气 | 122篇 |
武器工业 | 13篇 |
无线电 | 478篇 |
一般工业技术 | 595篇 |
冶金工业 | 137篇 |
原子能技术 | 55篇 |
自动化技术 | 718篇 |
出版年
2024年 | 51篇 |
2023年 | 120篇 |
2022年 | 214篇 |
2021年 | 307篇 |
2020年 | 242篇 |
2019年 | 197篇 |
2018年 | 216篇 |
2017年 | 219篇 |
2016年 | 211篇 |
2015年 | 223篇 |
2014年 | 294篇 |
2013年 | 369篇 |
2012年 | 377篇 |
2011年 | 348篇 |
2010年 | 297篇 |
2009年 | 318篇 |
2008年 | 267篇 |
2007年 | 209篇 |
2006年 | 198篇 |
2005年 | 134篇 |
2004年 | 95篇 |
2003年 | 84篇 |
2002年 | 88篇 |
2001年 | 72篇 |
2000年 | 52篇 |
1999年 | 42篇 |
1998年 | 34篇 |
1997年 | 16篇 |
1996年 | 24篇 |
1995年 | 11篇 |
1994年 | 21篇 |
1993年 | 7篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1962年 | 1篇 |
1956年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有5425条查询结果,搜索用时 0 毫秒
1.
陈如燕 《辐射研究与辐射工艺学报》1992,10(4):223-227
研究了工业糖化酶制剂经辐照处理后各项性能的变化。结果表明,经2kGy以下剂量的γ射线处理后,可提高其贮存稳定性,改善卫生品质,不影响其正常使用。 相似文献
2.
3.
Ahmet Ekmekyapar Nizamettin Demirkran Asm Künkül 《Chemical Engineering Research and Design》2008,86(9):1011-1016
Ulexite is an important boron mineral used for the production of boron compounds. The aims of this study are to examine the dissolution kinetics of ulexite in acetic acid solutions, and to present an alternative process to produce boric acid. In order to investigate the dissolution kinetics of ulexite in acetic acid solutions, the concentration of solution, reaction temperature, solid-to-liquid ratio, and particle size were selected as experimental parameters. It was determined that the dissolution rate of ulexite increased with increasing solution concentration and temperature and decreasing particle size and solid-to-liquid ratio. The activation energy of the process was found to be 55.8 kJ/mol. 相似文献
4.
5.
研制一种由醋酸乙烯、丙烯酸丁酯、特种单体共聚而成的水性交联型环保胶粘剂以替代目前广泛使用的氨基树脂,适应绿色环保要求。 相似文献
6.
为了探究影响GH5家族β-甘露聚糖酶最适pH的各种因素,利用该酶的序列信息,构建了基于氨基酸组成的β-甘露聚糖酶理化性质与其最适pH的相关性模型。结果表明:该酶N端氨基酸序列是影响其最适pH的重要因素,在243个理化性质中有17个呈极显著相关,其中7个呈正相关。优化的转移能量参数相关性最高,为0.78:7个正相关的理化性质中,与螺旋相关的理化性质占3个。优化的转移能量参数和螺旋是影响pH稳定性的最重要的因素。所建立的模型为研究该酶酸碱适应性机理提供了一种简单有效的方法。 相似文献
7.
Coverage is a fundamental problem in sensor networks. Sensor coverage, which reflects how well a sensor network is monitored by sensors, is an important measure for the quality of service (QoS) that a sensor network can provide. In mobile sensor networks, the mobility of sensor nodes can be utilized to enhance the coverage of the network. Since the movement of sensor nodes will consume much energy, this mobility of sensor nodes should be properly managed by some pre-defined schemes or protocols. By noticing this issue, some existing works have proposed several movement-assisted sensor deployment schemes. These works assume that the target field is a 2-dimensional space. In this paper, we study a generalized case of this problem whereby the target field can be a space which ranges from 1-dimensional to 3-dimensional. Two variations of the movement-assisted sensor deployment problem with different optimization objectives were formulated. We identify a set of basic attributes which can be used as guidelines for designing movement-assisted sensor deployment schemes. Based on these attributes, we propose efficient algorithms for both variants of the movement-assisted sensor deployment problem. 相似文献
8.
Self-repairing systems are those that are able to reconfigure themselves following disruptions to bring them back into a defined normal state. In this paper we explore the self-repair ability of some cellular automata-like systems, which differ from classical cellular automata by the introduction of a local diffusion process inspired by chemical signalling processes in biological development. The update rules in these systems are evolved using genetic programming to self-assemble towards a target pattern. In particular, we demonstrate that once the update rules have been evolved for self-assembly, many of those update rules also provide a self-repair ability without any additional evolutionary process aimed specifically at self-repair. 相似文献
9.
Copolymers of poly(acrylamide-co-acryloyloxyethyltrimethylammonium chloride or AM–CMA) and poly(acrylamide-co-methacryloyloxyethyltrimethylammonium chloride or AM–CMA) prepared by inverse emulsion polymerization were characterized by different analytical techniques. The chemical composition of the copolymers was estimated by elemental analysis and by nuclear magnetic resonance spectroscopy (NMR). NMR spectroscopy and computer simulation were further used for investigating the polymers' sequence distribution. The poly(AM–CMA) copolymers are chemically more homogeneous than are the poly(AM–CMA). The configurational propagation of dyads and triads for the homopolymers obeys Bernouilli's statistics. For the copolymers, the chemical sequences distribution is governed by Markov's first-order statistics. 相似文献
10.
Some volatile acids were found to dramatically reduce the effectiveness of additives based on 2,2,6,6-tetramethylpiperidine as photostabilizers for polypropylene films. Strong acids such as HCl, HBr, and HNO3 had the largest effect with sulfurous acid somewhat less detrimental. Weak organic acids did not impair the effectiveness of the hindered amine light stabilizers. The role of acid concentration and contact time were explored for the HCl–piperidyl additive system. Secondary and tertiary amines were included in the study as well as oligomeric additives and an N-oxyl derivative. The latter is less basic than the free amines, and it was correspondingly less effected by acid exposures. The possibilities for acid exposure during the compounding, fabrication, and use of stabilized polyolefin articles is discussed as well as the effects of acids in terms of proposed stabilization mechanisms for the hindered amines. 相似文献