全文获取类型
收费全文 | 32391篇 |
免费 | 2812篇 |
国内免费 | 1601篇 |
专业分类
电工技术 | 1740篇 |
技术理论 | 1篇 |
综合类 | 2312篇 |
化学工业 | 5596篇 |
金属工艺 | 1918篇 |
机械仪表 | 2111篇 |
建筑科学 | 2456篇 |
矿业工程 | 1026篇 |
能源动力 | 845篇 |
轻工业 | 2453篇 |
水利工程 | 626篇 |
石油天然气 | 1702篇 |
武器工业 | 240篇 |
无线电 | 3715篇 |
一般工业技术 | 3721篇 |
冶金工业 | 1465篇 |
原子能技术 | 405篇 |
自动化技术 | 4472篇 |
出版年
2024年 | 138篇 |
2023年 | 524篇 |
2022年 | 1061篇 |
2021年 | 1510篇 |
2020年 | 1168篇 |
2019年 | 980篇 |
2018年 | 1001篇 |
2017年 | 1074篇 |
2016年 | 1045篇 |
2015年 | 1437篇 |
2014年 | 1833篇 |
2013年 | 2141篇 |
2012年 | 2296篇 |
2011年 | 2476篇 |
2010年 | 2128篇 |
2009年 | 2049篇 |
2008年 | 1959篇 |
2007年 | 1769篇 |
2006年 | 1614篇 |
2005年 | 1200篇 |
2004年 | 945篇 |
2003年 | 902篇 |
2002年 | 1075篇 |
2001年 | 921篇 |
2000年 | 649篇 |
1999年 | 628篇 |
1998年 | 480篇 |
1997年 | 353篇 |
1996年 | 327篇 |
1995年 | 277篇 |
1994年 | 206篇 |
1993年 | 158篇 |
1992年 | 80篇 |
1991年 | 68篇 |
1990年 | 59篇 |
1989年 | 64篇 |
1988年 | 46篇 |
1987年 | 27篇 |
1986年 | 22篇 |
1985年 | 14篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1973年 | 7篇 |
1971年 | 4篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
The ennoblement of corrosion potential (Ecorr) of passive metal immersed in seawater was investigated with electrochemical technology and epifluorescence microscopy. The in situ observation showed that the bacteria number increased on the metal surface according to an exponential law which was in the same way with the ennoblement of Ecorr. At the same time, the anodic polarization current of high‐Mo stainless steel decreased in the initial days. According to the mix‐potential theory and the characteristics of polarization curves of high‐Mo steel in natural seawater, the ennoblement of corrosion potential may be induced by the decrease of the passive current density. 相似文献
2.
Gang Chen Zhonghua Yang Chor Ping Low 《Industrial Informatics, IEEE Transactions on》2006,2(4):269-280
In this paper, we address agent coordination from a dynamic systems perspective and propose a dynamic coordination model, which is inspired by biological metabolic systems. A new coordination mechanism through dynamic local adjustment (CDLA) is presented, and coordination is achieved when every agent utilizes explicitly the global system dynamics and performs iteratively a dynamic local adjustment procedure. The CDLA mechanism is investigated in an example multiagent shop floor system. The results show that the example manufacturing process is well-coordinated and the coordination approach is practically applicable and effective 相似文献
3.
Tee Downes 《Packaging Technology and Science》2003,16(2):87-88
4.
A series of novel block polymers of polyurethane (PU) and chitosan have been prepared in two steps. The first step is the preparation of PU prepolymer, obtained from polytetramethylene oxide glycol (PTMO, Mn = 1000), isophrone diisocyanate (IPDI), and 2,2′-dimethylol propionic acid (DMPA), followed by ionizing PU prepolymer with triethylamine (TEA). The second step involves PU chain-extended by water-soluble chitosan of low molecular weight (Mn = 5000) by self-emulsion polymerization method. The sizes of the latex particles, morphology, and copolymer architecture have been characterized by dynamic light scattering (DLS), general tensile test, infrared spectroscopy (IR), surface contact angle measurement, and transmission electron microscopy (TEM). Furthermore, it shows that the addition of chitosan remarkably increases anticoagulative property of PU elastomers confirmed by the recalcification time. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
5.
Cubic boron nitride (c-BN) crystals were synthesized in conditions of high temperature and high pressure (HTHP) when different kinds of bonded water were respectively added into the system of h-BN–Mg. All bonded water used in this work could reduce the temperature of growing c-BN compared to that in the system of h-BN–Mg. The c-BN color could change from black to yellow when certain amounts of bonded water, such as NiSO4·6H2O and CuSO4·5H2O, Mg(OH)2, were added. However, c-BN color remained black no matter how much bonded water, such as NiCl2·6H2O, CuCl2·2H2O, and SnCl2·2H2O, was added. The bonded water can be classified into Chlorine-containing bonded water (Cl-BW) and Chlorine-free bonded water (ClF-BW) according to their different characters and effects on the synthesized c-BN color. 相似文献
6.
An analytical method is presented for calculating the resonant frequency andQ-factor of a superconducting dielectric disk resonator operating in millimeter-wave regime with whispering-gallery mode. Resonant frequency shift due to the optical generation of quasi-particles in superconducting film is investigated as a function of photon flux. An optically tunable resonant frequency of about 500 MHz is estimated, and good agreement is found between numerical results and experimental ones. 相似文献
7.
本文主要完成了液态金属钠高温沸腾实验回路的应力分析与计算,确定了回路高温区连接管系的布置型式和支吊架系统,是该回路总体设计的重要组成部分。 相似文献
8.
本文介绍以PC-1500(A)型袖珍计算机为主体的地面放射性总量数据采集及处理系统的方案、硬件、软件及应用。 相似文献
9.
10.
本文对几种典型减振器做了一些分析,并根据我国主战坦克的特点提出了一种新的改进设计方案,在文中暂称为“复合作用”式减振器。它既能产生象摩擦减振器的摩擦阻尼,又能具有筒式减振器的小孔节流阻尼效果。两种阻尼的复合作用如调整适当,则对提高悬挂系统对地面情况的变化适应能力,改善车辆行驶平稳性和可靠性有很大的帮助。 相似文献