全文获取类型
收费全文 | 3855篇 |
免费 | 289篇 |
国内免费 | 87篇 |
专业分类
电工技术 | 188篇 |
综合类 | 164篇 |
化学工业 | 671篇 |
金属工艺 | 88篇 |
机械仪表 | 124篇 |
建筑科学 | 142篇 |
矿业工程 | 94篇 |
能源动力 | 94篇 |
轻工业 | 158篇 |
水利工程 | 36篇 |
石油天然气 | 63篇 |
武器工业 | 7篇 |
无线电 | 431篇 |
一般工业技术 | 487篇 |
冶金工业 | 1047篇 |
原子能技术 | 34篇 |
自动化技术 | 403篇 |
出版年
2024年 | 7篇 |
2023年 | 30篇 |
2022年 | 68篇 |
2021年 | 79篇 |
2020年 | 62篇 |
2019年 | 43篇 |
2018年 | 68篇 |
2017年 | 69篇 |
2016年 | 99篇 |
2015年 | 110篇 |
2014年 | 141篇 |
2013年 | 198篇 |
2012年 | 175篇 |
2011年 | 199篇 |
2010年 | 187篇 |
2009年 | 157篇 |
2008年 | 188篇 |
2007年 | 147篇 |
2006年 | 174篇 |
2005年 | 121篇 |
2004年 | 97篇 |
2003年 | 115篇 |
2002年 | 133篇 |
2001年 | 107篇 |
2000年 | 71篇 |
1999年 | 99篇 |
1998年 | 329篇 |
1997年 | 205篇 |
1996年 | 135篇 |
1995年 | 87篇 |
1994年 | 67篇 |
1993年 | 82篇 |
1992年 | 31篇 |
1991年 | 49篇 |
1990年 | 19篇 |
1989年 | 24篇 |
1988年 | 24篇 |
1987年 | 23篇 |
1986年 | 21篇 |
1985年 | 15篇 |
1984年 | 9篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 15篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 27篇 |
1976年 | 50篇 |
1975年 | 8篇 |
排序方式: 共有4231条查询结果,搜索用时 15 毫秒
991.
The effect of humidity on the photocatalytic degradation reaction of trichloroethylene (TCE) in gas phase was investigated
by using pretreated TiO2 sol-gel films. It was observed that the photocatalytic activity of the TiO2 films depended more greatly on the pretreatment conditions, for example, UV pre-illumination, than on the moisture content.
When the relative humidity was over 50%, the reaction rates decreased regardless of treatment conditions of the photocatalyst.
The photocatalytic decomposition rate of TCE increased with the increase of light intensity. However, the influence of humidity
on the reaction rate was less significant under the increased light intensity. The intermediates and byproducts of the reaction
were not changed in different humidity conditions. 相似文献
992.
为了研究低磷酸盐—低氢氧化钠水处理工艺下侵蚀性阴离子对碳钢的腐蚀 ,通过高压釜静态试验 ,计算在不同浓度下碳钢的腐蚀速度 ,测定溶液中总铁离子浓度以及对表面的 EPMA(Electron probe microanalysis,电子探针微量分析 )分析。结果表明 :高温下 ,Cl-、SO42 -是引起碳钢腐蚀的主要原因。它们能阻碍膜的形成。随着离子浓度的增大 ,当 CCl- >0 .4m g/L 时 ,碳钢的腐蚀速率明显增加 ,蚀孔增多 ,耐蚀性能降低 相似文献
993.
994.
This work experimentally investigates the use of induction‐heating to heat mold surfaces rapidly, and thus enhance the replication effect of the microstructure of light‐guided plates (LGP) in the injection molding process. This investigation employs a 2‐inch LGP injection mold as the experimental carrier, and compares the replication effect on the microstructure of induction heating with that of conventional oil‐heating. Temperature increases on the mold plate are examined using a thermal video system. The experimental results show that (1) the flat induction coil design promotes rapid surface heating. (2) Induction‐heating the mold surface to 110°C improves the replication rate of the height of the micro‐structure by up to 95%. (3) The LGP produced by induction heating has no significant residual stress. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
995.
996.
P.T. Joseph Nyan-Hwa Tai Yi-Chun Chen Hsiu-Fung Cheng I-Nan Lin 《Diamond and Related Materials》2008,17(4-5):476-480
Highly transparent ultrananocrystalline diamond (UNCD) films were deposited on quartz substrates using microwave plasma enhanced chemical vapor deposition (MPECVD) method. Low temperature growth of high quality transparent UNCD films was achieved by without heating the substrates prior to the deposition. Additionally, a new method to grow NCD and microcrystalline diamond (MCD) films on quartz substrates has been proposed. Field emission scanning electron microscopy (FESEM) and Raman spectroscopy were used to analyze the surface and structural properties of the films. The surface morphology of UNCD film shows very smooth surface characteristics. The transparent property studies of UNCD film on quartz substrate showed 90% transmittance in the near IR region. The transparent and dielectric properties of UNCD, NCD, and MCD films on quartz substrates were compared and reported. 相似文献
997.
主要对比了普通注塑等规聚丙烯(IPP)试样和振动注塑IPP试样晶型及力学性能的差别,研究了高模温条件下振动频率、振动压力对IPP样条力学性能和晶体形态的影响.结果表明,IPP样条的冲击强度比未振动试样有所提高;较高的模温则有利于β晶的生成.通过广角X射线衍射分析发现,在高温下,高频、低振动压力注射有利于IPP中β晶含量的增加,实现注射IPP试样的自增强和自增韧. 相似文献
998.
T.Y. Tsai Y.A. Li H.C. Su N.H. Tai K.C. Chen S.H. Lee L.H. Chan Y.Y. Chang 《Diamond and Related Materials》2008,17(4-5):594-597
Growth of carbon nanotubes (CNTs) at low temperature is a critical issue in the development of CNTs for diversified applications. The screen printing method, which used silver paste mixed with CNTs and glass powder as the raw material, was usually adopted for fabricating cathode of field emission device. In this work, Ni nanopowder mixed with commercial Ag-paste was prepared and screen-printed on the glass substrate, and then subjected to sintering in air at 500 °C. Growth of CNTs was performed in a self-designed cold-walled chemical vapour deposition (CVD) chamber at 500 °C under a pressure between 1 and 10 Torr. Field emission property was tested and the turn-on field of 2.4 V/μm was obtained for the specimen containing 2.7 wt.% Ni nanopowder. CNT density can be controlled by adjusting the concentration of Ni nanopowder in silver paste. This method proposed a simple route for synthesizing CNTs at relatively low temperature in a conventional CVD system, which is capable of fabricating large area cathode with proper CNT density. 相似文献
999.
钛酸镁基陶瓷是一种重要的功能陶瓷.本文采用固相反应法合成了Mg2TiO4粉末,主要研究了CuO对该体系陶瓷介电性能的影响.结果表明:添加CuO明显降低了烧结温度,当添加0.5%CuO时,烧结体介电性能良好,在1360℃烧结2h,烧结体的体积密度达到3.48g/cm3,在10KHz下介电常数达19.07,介电损耗为0.0017.XRD及SEM分析表明:烧结体的主晶相为Mg2TiO4,次晶相为CaTiO3,同时含有少量的MgTiO3,烧结体晶粒发育良好,平均晶粒尺寸为10~20μm. 相似文献
1000.
Gil Sun Lee Tai Young Kim Hyun Choi Dong June Ahn 《Korean Journal of Chemical Engineering》2009,26(3):691-696
Binary self-assembled monolayers (SAMs) have been much studied due to their high applicable potential as a model of biomimetic
surfaces. However, the research about miscibility of binary SAMs has not much been investigated yet. In this work, we focused
on analyzing the binary SAMs composed of mercaptohexadecanoic acid (MHA)-hexadecanthiol (HDT) on gold surfaces with Cassie
equation, Israelachvili equation, and FTIR spectroscopy to confirm that the binary SAMs are well mixed. As a result, MHA-HDT
binary SAMs are considered miscible because the result obtained from FTIR spectra is in good agreement with that calculated
by Israelachvili equation for the case that two different molecules are well mixed on the surface. Also, the adsorption of
cadmium ions on binary SAMs was confirmed by the appearance of carboxylate stretching bands.
This article is dedicated to Professor Chang Kyun Choi for celebrating his retirement from the School of Chemical and Biological
Engineering, Seoul National University. 相似文献