全文获取类型
收费全文 | 10185篇 |
免费 | 1842篇 |
国内免费 | 928篇 |
专业分类
电工技术 | 874篇 |
综合类 | 1012篇 |
化学工业 | 1159篇 |
金属工艺 | 981篇 |
机械仪表 | 590篇 |
建筑科学 | 416篇 |
矿业工程 | 270篇 |
能源动力 | 342篇 |
轻工业 | 173篇 |
水利工程 | 123篇 |
石油天然气 | 266篇 |
武器工业 | 103篇 |
无线电 | 3254篇 |
一般工业技术 | 1251篇 |
冶金工业 | 269篇 |
原子能技术 | 72篇 |
自动化技术 | 1800篇 |
出版年
2024年 | 67篇 |
2023年 | 199篇 |
2022年 | 325篇 |
2021年 | 335篇 |
2020年 | 412篇 |
2019年 | 458篇 |
2018年 | 372篇 |
2017年 | 562篇 |
2016年 | 572篇 |
2015年 | 516篇 |
2014年 | 694篇 |
2013年 | 650篇 |
2012年 | 673篇 |
2011年 | 647篇 |
2010年 | 475篇 |
2009年 | 518篇 |
2008年 | 513篇 |
2007年 | 529篇 |
2006年 | 502篇 |
2005年 | 444篇 |
2004年 | 423篇 |
2003年 | 527篇 |
2002年 | 549篇 |
2001年 | 558篇 |
2000年 | 407篇 |
1999年 | 308篇 |
1998年 | 175篇 |
1997年 | 165篇 |
1996年 | 103篇 |
1995年 | 69篇 |
1994年 | 52篇 |
1993年 | 26篇 |
1992年 | 27篇 |
1991年 | 21篇 |
1990年 | 21篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Polymer networks in which poly(propylene imine) dendrimers (Astramol?) are connected to each other by linear polytetrahydrofuran (polyTHF) segments, were prepared by two methods. The first method was a one‐step procedure in which bifunctionally living polyTHF, obtained by initiation of the THF polymerization with trifluoromethane sulfonic anhydride (triflic anhydride), was reacted with an amino‐dendrimer. This reaction was very fast but did not allow formation of the end products. The second method was a two‐step procedure. In a first step, living polyTHF, prepared with acryloyloxybutyl triflate as initiator, was grafted on an amino‐dendrimer, to form a star‐like, acrylate‐terminated polyTHF multi‐macromonomer with the dendrimer as core. In a second step, networks were obtained by Michael addition between the acrylate end‐groups and unreacted amino‐groups of the dendrimer. This cross‐linking reaction occurred spontaneously upon heating of the solution of the multi‐macromonomer with gelation times varying from a few minutes to a few hours, depending on the temperature and the composition of the prepolymers. With this method it was possible to prepare networks in the form of coatings or films. © 2003 Society of Chemical Industry 相似文献
3.
报导一种模糊逻辑控制系统的建模与优化方法。以此方法设计的模糊逻辑控制器,用于双波长稳频CO2激光器的控制得到令人满意的结果。 相似文献
4.
Panagiotis N. Zarros Myung J. Lee Tarek N. Saadawi 《Journal of Network and Systems Management》1994,2(4):361-382
In this paper, an algorithm to determine the set of packets generated continuously and periodically from different participants that are arriving at a node either for mixing at the master of a conference, or for simply playing back at a regular participant of a conference, is proposed. The essence of the algorithm is to estimate the expected packet arrival time (or reference time) for each participant. With the reference time at hand, the maximum jitter and the optimum waiting time for a mixer to wait packets from all participants can be determined. An enhancement to improve synchronization which deals with the estimation of the time offsets between the individual periods of the sources and the period of the receiver is also presented. The error of the proposed algorithm is enumerated by the Chernoff bound and demonstrated by simulation and is shown to be acceptable in practical application. The algorithm can also be employed when traffic sources operate with different periods. 相似文献
5.
6.
阐述了城域光网络(MON)技术的出现背景、定义、技术方案和特点,以及与现有城域基础设施的比较,突出说明了其应用上的竞争优势。最后介绍了MON的现状和前景展望。 相似文献
7.
8.
9.
10.
By using scanning polarization force microscopy,the deliquescence process and the atomic steps on the cleavage surface of CaCO3 in air were studied in situ.Under an exposure to medium umidity(-57%),the sloiw step movement has been observed. 相似文献