全文获取类型
收费全文 | 905篇 |
免费 | 20篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 58篇 |
综合类 | 3篇 |
化学工业 | 257篇 |
金属工艺 | 26篇 |
机械仪表 | 20篇 |
建筑科学 | 20篇 |
能源动力 | 40篇 |
轻工业 | 87篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 59篇 |
一般工业技术 | 190篇 |
冶金工业 | 72篇 |
原子能技术 | 22篇 |
自动化技术 | 73篇 |
出版年
2024年 | 3篇 |
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 15篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 13篇 |
2017年 | 12篇 |
2016年 | 23篇 |
2015年 | 21篇 |
2014年 | 21篇 |
2013年 | 44篇 |
2012年 | 42篇 |
2011年 | 52篇 |
2010年 | 47篇 |
2009年 | 45篇 |
2008年 | 64篇 |
2007年 | 48篇 |
2006年 | 34篇 |
2005年 | 33篇 |
2004年 | 27篇 |
2003年 | 34篇 |
2002年 | 27篇 |
2001年 | 32篇 |
2000年 | 20篇 |
1999年 | 9篇 |
1998年 | 25篇 |
1997年 | 19篇 |
1996年 | 22篇 |
1995年 | 11篇 |
1994年 | 16篇 |
1993年 | 15篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 9篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1973年 | 3篇 |
1969年 | 3篇 |
排序方式: 共有932条查询结果,搜索用时 15 毫秒
101.
102.
A single-phase diode bridge rectifier with a filter capacitor on the dc side is often employed to convert ac input into a dc voltage. The input current of the rectifier contains harmonic currents which cause undesirable power line effects. Recently, a method using the time domain analysis has been proposed to calculate the harmonic currents of rectifier considering noninfinite capacitance, i.e., non-zero dc side impedance. This method is very accurate, but it requires a long computing time and a complicated algorithm. This paper proposes a new method that makes it possible to easily calculate the harmonic currents taking into account the effects of the ac and dc side impedances of rectifier. The proposed method, which is based on the frequency domain method, can be executed only with the algebraic computation, and its accuracy is quite high. The validity of the proposed method is also demonstrated by comparison with the results of time simulation. 相似文献
103.
Dechlorination of chlorobenzene compounds on flyash by using a solution of calcium hydroxide and sulfur in aqueous/organic solvent at 60–170 °C, under oxygen deficient conditions was studied. High percentage of dechlorination was obtained under certain reaction conditions. The results suggested that at 90 °C, metals in general and copper and lead in particular enhanced the catalytic potential of flyash for dechlorination by hydrodechlorination and substitution reactions. But at high temperatures (120–170 °C), dechlorination process was adversely affected by these metals. The effects of water, organic solvents, temperatures and heating time, were studied and reactions conditions were optimized to get maximum dechlorination. 相似文献
104.
Morita T Konishi M Fukuoka T Imura T Kitamoto D 《Journal of Bioscience and Bioengineering》2007,104(1):78-81
Microbial conversion of glycerol into functional bio-based materials was investigated, aiming to facilitate the utilization of waste glycerol. A basidiomycete yeast, Pseudozyma antarctica JCM 10317, efficiently produced mannosylerythritol lipids (MELs) as glycolipid biosurfactants from glycerol. The amount of MEL yield reached 16.3 g l(-1) by intermittent feeding of glycerol. 相似文献
105.
Tojo Y Syou R Yoshida M Momose J Ginya H Takahashi M Tajima H Yohda M 《Journal of Bioscience and Bioengineering》2006,102(5):474-477
A single-nucleotide-polymorphism-typing method using a novel three-dimensional DNA microarray, Bio-Strand, is promising because it is rapid, inexpensive and easily automated. It has been developed with the intent to overcome the drawbacks of conventional DNA microarrays, which use flat surfaces and impermeable materials such as glass slides; Bio-Strand as a novel DNA microarray, with its permeability, has a significantly improved stability compared with conventional DNA microarrays that use impermeable materials. In this study, we have developed a simple method of pretreating a polyamide monofilament to increase its surface area and to make it permeable, which makes Bio-Strand more sensitive and stable, allowing it to be adapted for clinical diagnostic applications. The fluorescence signal obtained with a nylon 6 monofilament pretreated under optimal conditions (hydrolysis by 5 M HCl/ethanol followed by washing with 50% ethanol and 100% ethanol) was significantly stronger than that obtained with an untreated monofilament. 相似文献
106.
107.
108.
A two-stage evolutionary method is developed to synthesize an optimal energy integrated distillation separation process: the search of the separation sequence, and the introduction of energy integration to the given separation sequence. For the former an evolutionary procedure first generating initial separation sequences and then evolving them is developed. For the latter an evolutionary procedure, first indicating the direction of the evolution by the thermodynamic analysis and then estimating it based on the objective function, is developed. An example problem of a five-component separation demonstrates the effectiveness of this proposed method. 相似文献
109.
Shoichi MATSUDA Naomichi SAJI Minoru YAGA Masaaki ISHIKAWA Kenyu OYAKAWA 《热科学学报(英文版)》2010,19(3):228-233
This paper will present the characteristics of flow behavior and thermal field of both free and
impingement jet issued from a circular orifice nozzle at Re=8900.The flow behavior of a single round
jet and impingement jet was observed by smoke flow visualization recorded by a high speed camera
using 5000 frame per second.Heat transfer coefficient on the impingement surface was measured by
means of infrared camera (TVS-8500,Avio) with a two-dimensional array of Indeum-Antimony (In Sb)
sensors varying in the separation distance between the nozzle and the target plate.The heat transfer
coefficient changes in time and spatial.Therefore,the root mean square distribution of the heat
transfer was obtained from the data.As a result,it was confirmed that the longitudinal vortex was
observed outside of the ring vortex,and then the longitudinal vortex was penetrated in the jet
flow.Moreover,the high value of root mean square of the heat transfer coefficient has spread radially
in stripy manner,which is caused as the results of the longitudinal vortexes flowing in the radial
direction on the impingement plate. 相似文献
impingement jet issued from a circular orifice nozzle at Re=8900.The flow behavior of a single round
jet and impingement jet was observed by smoke flow visualization recorded by a high speed camera
using 5000 frame per second.Heat transfer coefficient on the impingement surface was measured by
means of infrared camera (TVS-8500,Avio) with a two-dimensional array of Indeum-Antimony (In Sb)
sensors varying in the separation distance between the nozzle and the target plate.The heat transfer
coefficient changes in time and spatial.Therefore,the root mean square distribution of the heat
transfer was obtained from the data.As a result,it was confirmed that the longitudinal vortex was
observed outside of the ring vortex,and then the longitudinal vortex was penetrated in the jet
flow.Moreover,the high value of root mean square of the heat transfer coefficient has spread radially
in stripy manner,which is caused as the results of the longitudinal vortexes flowing in the radial
direction on the impingement plate. 相似文献
110.
Masaaki Hirayama Noriyuki Sonoyama Takeshi Abe Machiko Minoura Masumi Ito Daisuke Mori Atsuo Yamada Ryoji Kanno Takahito Terashima Mikio Takano Kazuhisa Tamura Jun’ichiro Mizuki 《Journal of power sources》2007
A new experimental technique was developed for detecting structure changes at electrode/electrolyte interface of lithium cell using X-ray reflectometry and two-dimensional model electrodes with a restricted lattice-plane. The electrodes were constructed with an epitaxial film of LiCoO2 synthesized by pulsed laser deposition method. The orientation of the epitaxial film depends on the substrate plane; the 2D layer of LiCoO2 is parallel to the SrTiO3 (1 1 1) substrate ((0 0 3)LiCoO2//(1 1 1)SrTiO3), while the 2D layer is perpendicular to the SrTiO3 (1 1 0) substrate ((1 1 0)LiCoO2//(1 1 0)SrTiO3). The anisotropic properties were confirmed by electrochemical measurements. Ex situ X-ray reflectivity measurements indicated that the impurity layer existed on the as-grown LiCoO2 was dissolved and a new SEI layer with lower density was formed after soaking into the electrolyte. In situ X-ray reflectivity measurements indicated that the surface roughness of the intercalation (1 1 0) plane increased with applying voltages, while no significant changes in surface morphology were observed for the intercalation non-active (0 0 3) plane during the pristine stage of the charge–discharge process. 相似文献