全文获取类型
收费全文 | 2994篇 |
免费 | 146篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 28篇 |
综合类 | 9篇 |
化学工业 | 803篇 |
金属工艺 | 78篇 |
机械仪表 | 66篇 |
建筑科学 | 149篇 |
矿业工程 | 7篇 |
能源动力 | 77篇 |
轻工业 | 203篇 |
水利工程 | 40篇 |
石油天然气 | 17篇 |
无线电 | 263篇 |
一般工业技术 | 620篇 |
冶金工业 | 467篇 |
原子能技术 | 11篇 |
自动化技术 | 306篇 |
出版年
2023年 | 23篇 |
2022年 | 57篇 |
2021年 | 70篇 |
2020年 | 48篇 |
2019年 | 65篇 |
2018年 | 66篇 |
2017年 | 64篇 |
2016年 | 80篇 |
2015年 | 52篇 |
2014年 | 111篇 |
2013年 | 152篇 |
2012年 | 115篇 |
2011年 | 156篇 |
2010年 | 124篇 |
2009年 | 112篇 |
2008年 | 113篇 |
2007年 | 132篇 |
2006年 | 105篇 |
2005年 | 89篇 |
2004年 | 65篇 |
2003年 | 84篇 |
2002年 | 59篇 |
2001年 | 43篇 |
2000年 | 33篇 |
1999年 | 50篇 |
1998年 | 138篇 |
1997年 | 108篇 |
1996年 | 78篇 |
1995年 | 59篇 |
1994年 | 56篇 |
1993年 | 43篇 |
1992年 | 29篇 |
1991年 | 33篇 |
1990年 | 36篇 |
1989年 | 25篇 |
1988年 | 24篇 |
1987年 | 25篇 |
1986年 | 28篇 |
1985年 | 27篇 |
1984年 | 34篇 |
1983年 | 30篇 |
1982年 | 26篇 |
1981年 | 21篇 |
1980年 | 30篇 |
1979年 | 18篇 |
1978年 | 23篇 |
1977年 | 26篇 |
1976年 | 26篇 |
1975年 | 20篇 |
1974年 | 17篇 |
排序方式: 共有3144条查询结果,搜索用时 0 毫秒
1.
Anaerobic co-digestion of organic wastes from households, slaughterhouses and meat processing industries was optimised in a half technical scale plant. The plant was operated for 130 days using two different substrates under organic loading rates of 10 and 12 kgCOD.m(-3).d(-1). Since the substrates were rich in fat and protein components (TKN: 12 g.kg(-1) the treatment was challenging. The process was monitored on-line and in the laboratory. It was demonstrated that an intensive and stable co-digestion of partly hydrolysed organic waste and protein rich slaughterhouse waste can be achieved in the balance of inconsistent pH and buffering NH4-N. In the first experimental period the reduction of the substrate COD was almost complete in an overall stable process (COD reduction >82%). In the second period methane productivity increased, but certain intermediate products accumulated constantly. Process design options for a second digestion phase for advanced degradation were investigated. Potential causes for slow and reduced propionic and valeric acid degradation were assessed. Recommendations for full-scale process implementation can be made from the experimental results reported. The highly loaded and stable codigestion of these substrates may be a good technical and economic treatment alternative. 相似文献
2.
J.A. Bakken L. Barone D. Braun M. Caillat C. Dionisi C. Dor H. Elmamouni F. Ferroni G.L. Grazer J.T. He R. Herbiet B. Ille P. Lecomte E. Longo P.F. Loverre Y.S. Lu J.P. Martin U. Micke R.P. Mount P.A. Pirou H.-G. Sander D. Schmitz M. Schneegans D.P. Stickland R.L. Sumner K.L. Tung E. Valente M. Vivargent 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,228(2-3):294-302
A calorimeter of 25 bismuth germanate (BGO) crystals equipped with silicon photodiode readout has been tested at the CERN SPS in the energy range 1–50 GeV. The response for electrons has been shown to be linear in this energy range and the rms resolution obtained (
) is approximately 1%, for E > 4 GeV. The electron/pion separation was found to be better than 1:500 in the energy range 1–20 GeV. Data on lateral and longitudinal shower development were compared with the results of a Monte Carlo simulation using the SLAC-EGS program and found to be in good agreement. 相似文献
3.
Yunlei Li Dick de Ridder Robert P.W. Duin Marcel J.T. Reinders 《Pattern recognition》2008,41(1):320-330
Samples can be measured with different precisions and reliabilities in different experiments, or even within the same experiment. These varying levels of measurement noise may deteriorate the performance of a pattern recognition system, if not treated with care. Here we seek to investigate the benefit of incorporating prior knowledge about measurement noise into system construction. We propose a kernel density classifier which integrates such prior knowledge. Instead of using an identical kernel for each sample, we transform the prior knowledge into a distinct kernel for each sample. The integration procedure is straightforward and easy to interpret. In addition, we show how to estimate the diverse measurement noise levels in a real world dataset. Compared to the basic methods, the new kernel density classifier can give a significantly better classification performance. As expected, this improvement is more obvious for small sample size datasets and large number of features. 相似文献
4.
MarcelvanRoosmalen MatthiasLocher 《世界电子元器件》2004,(12):75-76
射频存储系统的目标市场有两个,一个是宽带网络,一个是无线局域网:下图介绍的是第一公里的无线宽带接入系统。图的中央有一个中枢(hub),它的周围是一个分布网络。这是一个包括光和电的、数据和模拟结合的网络,这种系统在中国的大城市都有广泛的部署。圆圈是飞利浦开发的一些结点、中枢和分布网络,包括放大器和光电设备。 相似文献
5.
What if every public space and surface were transformed into an interactive experience - capturing our movements, gestures, sounds and actions and using these to produce new sounds, images, text and actions? Bus stops could come alive and talk back, advertisements could look back at you and talk to you and public park robotic devices could play games with you. Will public places eventually become our social barometer as well as director? Will billboards display the populace's discourse? The author look at some special streets in France where the city is literally alive with art and explores what it might mean for us to live in a world of artistic interactivity. 相似文献
6.
7.
Experience with electrical diagnostic and high-potential tests, performed at the terminals of unshielded cables in older nuclear and thermal plants is presented. The three basic types of cable-low- and high-voltage power cables, control cables and instrumentation cables-that are important to the reliable operation of a generating station and large industrial plants are described, and their aging mechanisms are indicated. Dielectric testing of unshielded cables, the effect of grounding, field testing of station cables, and insulation characterization at low frequencies are discussed 相似文献
8.
9.
The fabrication and characterization of two‐photon polymerized features written within and outside of colloidal crystals is presented. Two‐photon polymerization (TPP) response diagrams are introduced and developed to map the polymerization and damage thresholds for features written via modulated beam rastering. The use of tris[4‐(7‐benzothiazol‐2‐yl‐9,9‐diethylfluoren‐2‐yl)phenyl]amine (AF‐350) as an initiator for TPP is demonstrated for the first time and TPP response diagrams illustrate the polymerization window. These diagrams also demonstrate that the polymerization behavior within and outside of colloidal crystals is similar and electron microscopy reveals nearly identical resolution. Fluorescence confocal microscopy further enables visualization of non‐self‐supporting, three‐dimensional TPP features within self‐assembled photonic crystals. Finally, microspot spectroscopy is collected from a two‐photon feature written within a colloidal crystal and this is compared with simulation. 相似文献
10.