全文获取类型
收费全文 | 5145篇 |
免费 | 219篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 82篇 |
综合类 | 30篇 |
化学工业 | 1504篇 |
金属工艺 | 96篇 |
机械仪表 | 94篇 |
建筑科学 | 332篇 |
矿业工程 | 23篇 |
能源动力 | 99篇 |
轻工业 | 413篇 |
水利工程 | 34篇 |
石油天然气 | 2篇 |
无线电 | 318篇 |
一般工业技术 | 1088篇 |
冶金工业 | 473篇 |
原子能技术 | 42篇 |
自动化技术 | 747篇 |
出版年
2023年 | 39篇 |
2022年 | 49篇 |
2021年 | 85篇 |
2020年 | 74篇 |
2019年 | 69篇 |
2018年 | 83篇 |
2017年 | 99篇 |
2016年 | 142篇 |
2015年 | 102篇 |
2014年 | 163篇 |
2013年 | 252篇 |
2012年 | 221篇 |
2011年 | 321篇 |
2010年 | 246篇 |
2009年 | 254篇 |
2008年 | 248篇 |
2007年 | 236篇 |
2006年 | 237篇 |
2005年 | 203篇 |
2004年 | 174篇 |
2003年 | 136篇 |
2002年 | 112篇 |
2001年 | 87篇 |
2000年 | 89篇 |
1999年 | 100篇 |
1998年 | 112篇 |
1997年 | 83篇 |
1996年 | 91篇 |
1995年 | 69篇 |
1994年 | 71篇 |
1993年 | 75篇 |
1992年 | 73篇 |
1991年 | 56篇 |
1990年 | 59篇 |
1989年 | 56篇 |
1988年 | 61篇 |
1987年 | 54篇 |
1986年 | 46篇 |
1985年 | 45篇 |
1984年 | 54篇 |
1983年 | 38篇 |
1982年 | 47篇 |
1981年 | 47篇 |
1980年 | 31篇 |
1979年 | 29篇 |
1978年 | 34篇 |
1977年 | 31篇 |
1976年 | 33篇 |
1975年 | 37篇 |
1973年 | 31篇 |
排序方式: 共有5377条查询结果,搜索用时 34 毫秒
21.
22.
23.
24.
In order to increase the efficiency of waste utilization in thermal conversion processes, pre-treatment is advantageous. With the Herhof Stabilat® process, residual domestic waste is upgraded to waste-derived fuel by means of biological drying and mechanical separation of inerts and metals. The dried and homogenized waste-derived Stabilat® fuel has a relatively high calorific value and contains high volatile matter which makes it suitable for gasification. As a result of extensive mechanical treatment, the Stabilat® produced is of a fluffy appearance with a low density. A two-stage gasifier, based on a parallel-arranged bubbling fluidized bed and a fixed bed reactor, has been developed to convert Stabilat® into hydrogen-rich product gas. This paper focuses on the design and construction of the configured laboratory-scale gasifier and experience with its operation. The processing of low-density fluffy waste-derived fuel using small-scale equipment demands special technical solutions for the core components as well as for the peripheral equipment. These are discussed here. The operating results of Stabilat® gasification are also presented. 相似文献
25.
26.
Wolfgang Appelt 《Computer Standards & Interfaces》1988,7(4):377-385
The Office Document Architecture (ODA) is an International Standard which is developed by TC 97/sc 18 of the International Organization for Standardization (ISO) in close collaboration with CCITT's Study Group VIII and with ECMA. This paper describes the current state of a formal specification of the ODA document structures by mathematical means and its use for conformance specification and conformance testing. 相似文献
27.
Packed beds of fuel wood chips are commonly found in thermal conversion processes such as combustion or gasification. Wood chips in particular are mostly used as fuel for small-scale domestic heating boilers but also for commercial-scale combustion units. The characterization of spatial voidage distribution inside the wood chip beds is of great importance for flow and reactor modelling. This study focuses on the radial porosity variations of cylindrical beds of three different types of commercially available wood chips including chips classified as G30 size class. The conventional technique of consolidating packed beds with a resin was chosen as the experimental procedure. The radial voidage distribution in different cylindrical beds is determined by image analysis of sections of the solidified packings. Additionally, a packing of monosized spheres was investigated in order to assess the selected procedure in comparison with widely available literature data for spheres. The results are discussed and summarized in a mathematical expression correlating the radial voidage distribution depending on average wood chip size, packing core porosity and dimensionless distance from the tube wall. 相似文献
28.
29.
Christoph Böhringer Wolfgang Wiegard Collin Starkweather Anna Ruocco 《Computational Economics》2003,22(1):75-109
The double or even triple dividend hypothesis of green tax reforms has beena major issue of dispute in both the scientific community and the politicalarena during the last decade. Theoretical analysis has provided a number ofimportant qualitative insights to the debate but lacks of actual policyrelevance due to very restrictive assumptions. Applied research that takes thestep from stylized analytical to complex numerical models usually comes as ablackbox to non-expert modelers. This paper aims at bridging the gap betweenstylized theoretical work and numerical analysis. We develop a flexible,interactive simulation model which is accessible underhttp://brw.zew.de. Users can specify their own green tax reforms andevaluate the induced economic and environmental effects. Based on illustrativesimulations, we demonstrate the usefulness of our do-it-yourself approach fora better understanding of the double (triple) dividend hypothesis. 相似文献
30.