全文获取类型
收费全文 | 8617篇 |
免费 | 588篇 |
国内免费 | 373篇 |
专业分类
电工技术 | 240篇 |
综合类 | 462篇 |
化学工业 | 1283篇 |
金属工艺 | 320篇 |
机械仪表 | 310篇 |
建筑科学 | 646篇 |
矿业工程 | 109篇 |
能源动力 | 406篇 |
轻工业 | 729篇 |
水利工程 | 214篇 |
石油天然气 | 126篇 |
武器工业 | 37篇 |
无线电 | 1014篇 |
一般工业技术 | 1533篇 |
冶金工业 | 1138篇 |
原子能技术 | 471篇 |
自动化技术 | 540篇 |
出版年
2024年 | 22篇 |
2023年 | 147篇 |
2022年 | 172篇 |
2021年 | 253篇 |
2020年 | 219篇 |
2019年 | 227篇 |
2018年 | 214篇 |
2017年 | 271篇 |
2016年 | 287篇 |
2015年 | 262篇 |
2014年 | 371篇 |
2013年 | 705篇 |
2012年 | 431篇 |
2011年 | 630篇 |
2010年 | 476篇 |
2009年 | 451篇 |
2008年 | 432篇 |
2007年 | 513篇 |
2006年 | 486篇 |
2005年 | 352篇 |
2004年 | 359篇 |
2003年 | 278篇 |
2002年 | 297篇 |
2001年 | 221篇 |
2000年 | 168篇 |
1999年 | 152篇 |
1998年 | 208篇 |
1997年 | 131篇 |
1996年 | 120篇 |
1995年 | 83篇 |
1994年 | 78篇 |
1993年 | 61篇 |
1992年 | 48篇 |
1991年 | 54篇 |
1990年 | 55篇 |
1989年 | 49篇 |
1988年 | 32篇 |
1987年 | 24篇 |
1986年 | 20篇 |
1985年 | 38篇 |
1984年 | 25篇 |
1983年 | 21篇 |
1982年 | 16篇 |
1981年 | 7篇 |
1966年 | 7篇 |
1964年 | 22篇 |
1963年 | 11篇 |
1960年 | 9篇 |
1959年 | 7篇 |
1958年 | 6篇 |
排序方式: 共有9578条查询结果,搜索用时 0 毫秒
1.
一场新型冠状病毒肺炎疫情的爆发给染料行业的发展带来了影响,既有负面消极,也有积极影响。疫情将促进染料行业绿色发展,推动染料行业走向信息化、智能化时代,走向高质量发展,指出只要坚持绿色、创新和智能化,就能战胜疫情,推动中国染料行业稳健发展。 相似文献
2.
We investigate the effect of dopant random fluctuation on threshold voltage and drain current variation in a two-gate nanoscale transistor. We used a quantum-corrected technology computer aided design simulation to run the simulation (10000 randomizations). With this simulation, we could study the effects of varying the dimensions (length and width), and thicknesses of oxide and dopant factors of a transistor on the threshold voltage and drain current in subthreshold region (off) and overthreshold (on). It was found that in the subthreshold region the variability of the drain current and threshold voltage is relatively fixed while in the overthreshold region the variability of the threshold voltage and drain current decreases remarkably, despite the slight reduction of gate voltage diffusion (compared with that of the subthreshold). These results have been interpreted by using previously reported models for threshold current variability, load displacement, and simple analytical calculations. Scaling analysis shows that the variability of the characteristics of this semiconductor increases as the effects of the short channel increases. Therefore, with a slight increase of length and a reduction of width, oxide thickness, and dopant factor, we could correct the effect of the short channel. 相似文献
3.
《Intermetallics》2015
The structural changes induced in a CoCrCuFeNi multicomponent nano-crystalline high-entropy alloy (HEA) under fast electron irradiation were investigated by in-situ transmission electron microscopy (TEM) using a high voltage electron microscope (HVEM). A fine-grained face centered cubic (fcc) single phase was obtained in the sputtered specimens. The fcc solid solution showed high phase stability against irradiation over a wide temperature range from 298 to 773 K, and remained as the main constituent phase even when the samples were irradiated up to 40 displacement per atom (dpa). Moreover, the irradiation did not seem to induce grain coarsening. This is the first report on the irradiation damage in 5-component HEA under MeV electron irradiation. 相似文献
4.
We study a two-agent scheduling problem in a two-machine permutation flowshop with learning effects. The objective is to minimize the total completion time of the jobs from one agent, given that the maximum tardiness of the jobs from the other agent cannot exceed a bound. We provide a branch-and-bound algorithm for the problem. In addition, we present several genetic algorithms to obtain near-optimal solutions. Computational results indicate that the algorithms perform well in either solving the problem or efficiently generating near-optimal solutions. 相似文献
5.
Luca Pietrobon Lorenzo Fallarino Andreas Berger Andrey Chuvilin Flix Casanova Luis E. Hueso 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(47):6295-6301
Graphene has been predicted to develop a magnetic moment by proximity effect when placed on a ferromagnetic film, a promise that could open exciting possibilities in the fields of spintronics and magnetic data recording. In this work, the interplay between the magnetoresistance of graphene and the magnetization of an underlying ferromagnetic insulating film is studied in detail. A clear correlation between both magnitudes is observed but through a careful modeling of the magnetization and the weak localization measurements, that such correspondence can be explained by the effects of the magnetic stray fields arising from the ferromagnetic insulator is found. The results emphasize the complexity arising at the interface between magnetic and 2D materials. 相似文献
6.
G. Murali Dhar B. N. Srinivas M. S. Rana Manoj Kumar S. K. Maity 《Catalysis Today》2003,86(1-4):45-60
Support effects form important aspect of hydrodesulfurization (HDS) studies and mixed oxide supports received maximum attention in the last two decades. This review will focus attention on studies on mixed oxide supported Mo and W catalysts. For convenience of discussion, these are divided into Al2O3 containing mixed oxide supports, TiO2 containing mixed oxide supports, ZrO2 containing mixed oxide supports and other mixed oxide supports containing all the rest. TiO2 containing mixed oxides received maximum attention, especially TiO2–Al2O3 supported catalysts. A brief discussion about their prospects for application to ultradeep desulfurization is also included. An overview of the available literature with emphasis on research carried out in our laboratory form the contents of this publication. 相似文献
7.
M. Liess R. Hua K. Elsenaar 《The International Journal of Advanced Manufacturing Technology》2002,20(1):58-62
Cables to moving parts on a linear actuator in production machines, such as pick-and-place machines, are a source of unreliability
owing to the possible breaking of a cable. They further reduce the positioning precision of the actuator owing to additional
forces. Slotted waveguide systems for rail vehicles based on 2.4 GHz transmission frequency are well known, but transmitters/receivers
and waveguides are bulky. The paper reports on the reduction in size of the equipment, adapted to 5.8 GHz using a commercial
off-the-shelf RadioLan communication module. Further, the efficient termination of the wave-guide and a new way to reduce
standing-wave effects is also discussed. 相似文献
8.
目的观察迪银片治疗银屑病的临床疗效。方法30例银屑病患者,口服迪银片8周,采用PASI评分法评价治疗前后效果,并观察有无不良反应发生。结果患者痊愈率56.7%,显效率36.7%,总有效率93.3%,无明显的不良反应。结论迪银片是临床治疗银屑病的有效药物之一。 相似文献
9.
Yu.V. Butenko P.R. Coxon M. Yeganeh A.C. Brieva K. Liddell V.R. Dhanak L. iller 《Diamond and Related Materials》2008,17(6):962-966
It is generally accepted that diamond is resistant to a wide spectrum of electromagnetic radiation from the ultraviolet through to the soft X-ray range, which makes it very attractive for the fabrication of diamond-based photodetectors. However the effect of photon radiation on the diamond structure has not yet been examined. In the work presented here, photoelectron spectroscopy has been used to study the graphitization of nanodiamond crystallites exposed to extreme ultraviolet radiation. Under such irradiation, the surface hydrogen groups and graphite species are found to prevent graphitization. The mechanism of radiation-induced nanodiamond graphitization is discussed. 相似文献
10.
Mg-Si基热电化合物的研究现状 总被引:1,自引:0,他引:1
重点综述了Mg-Si基热电化合物的基本特性,该体系热电材料的制备方法与掺杂改性的研究进展,并提出了要重点解决的问题。 相似文献