全文获取类型
收费全文 | 2285篇 |
免费 | 30篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 17篇 |
化学工业 | 240篇 |
金属工艺 | 49篇 |
机械仪表 | 36篇 |
建筑科学 | 121篇 |
矿业工程 | 7篇 |
能源动力 | 66篇 |
轻工业 | 202篇 |
水利工程 | 14篇 |
石油天然气 | 10篇 |
无线电 | 172篇 |
一般工业技术 | 372篇 |
冶金工业 | 771篇 |
原子能技术 | 13篇 |
自动化技术 | 226篇 |
出版年
2022年 | 14篇 |
2021年 | 13篇 |
2019年 | 18篇 |
2018年 | 13篇 |
2017年 | 21篇 |
2015年 | 20篇 |
2014年 | 24篇 |
2013年 | 115篇 |
2012年 | 55篇 |
2011年 | 85篇 |
2010年 | 70篇 |
2009年 | 59篇 |
2008年 | 71篇 |
2007年 | 77篇 |
2006年 | 67篇 |
2005年 | 71篇 |
2004年 | 62篇 |
2003年 | 56篇 |
2002年 | 42篇 |
2001年 | 49篇 |
2000年 | 46篇 |
1999年 | 52篇 |
1998年 | 216篇 |
1997年 | 119篇 |
1996年 | 82篇 |
1995年 | 72篇 |
1994年 | 75篇 |
1993年 | 64篇 |
1992年 | 36篇 |
1991年 | 22篇 |
1990年 | 20篇 |
1989年 | 20篇 |
1988年 | 21篇 |
1987年 | 21篇 |
1986年 | 22篇 |
1985年 | 23篇 |
1984年 | 21篇 |
1983年 | 14篇 |
1982年 | 26篇 |
1981年 | 24篇 |
1980年 | 18篇 |
1979年 | 24篇 |
1978年 | 24篇 |
1977年 | 37篇 |
1976年 | 60篇 |
1975年 | 16篇 |
1974年 | 13篇 |
1973年 | 19篇 |
1972年 | 14篇 |
1968年 | 13篇 |
排序方式: 共有2316条查询结果,搜索用时 0 毫秒
1.
Many current implementations of protocols such as the Transmission Control Protocol/Internet Protocol (TCP/IP) are inefficient because data are often accessed more frequently than necessary. Three techniques that reduce the need for memory bandwidth are proposed. The techniques are copy-on-write, page remapping, and single-copy. Afterburner, a network-independent card that provides the services that are necessary for a single-copy protocol stack, is described. The card has 1 MByte of local buffers and provides a simple interface to a variety of network link adapters, including HIPPI and asynchronous transfer mode (ATM). Afterburner can support transfers to and from the link adapter card at rates up to 1 Gbit/s. An implementation of TCP/IP that uses the features provided by Afterburner to reduce the movement of data to a single copy is discussed. Measurements of the end-to-end performance of Afterburner and the single-copy implementation of TCP/IP are presented 相似文献
2.
S. F. Edwards 《Polymer International》1985,17(2):122-125
Elasticity is discussed as an aspect of viscoelasticity, which is described by the tube model. The effects of both crosslinks and entanglements contribute to this model and a discussion of how these effects can be quantified is given. At high enough concentration, entanglements ensure the existence of elastic effects even without crosslinks, and a theory is presented on how this dynamical phase change comes about. 相似文献
3.
Lee C. Chang Ph.D. Associate Professor Director Jeri L. Edwards Senior Manager 《Computers & Industrial Engineering》1991,21(1-4):147-151
Image processing allows the automation of the business transaction, turning “paper factories” into “image factories.” This burgeoning new area of computerization needs new paradigms, theories, and methods to maximize its effectiveness at cutting time and costs. This paper investigates what this new area of computerization can gain from CIM technology. It examines the similarities between the processing of computer images in a paperless business environment and the processing of materials into products in the manufacturing plant. These similarities will allow us to apply mature, well-tested CIM techniques to emerging image factories. 相似文献
4.
The authors highlight several possible ways in which the construction industry could lower present emissions of the greenhouse gas, carbon dioxide. It is an excellent discussion document and is recommended reading. 相似文献
5.
This paper presents the results of laboratory measurements of relative permeability for two phase flow in partially saturated samples of unconsolidated sands. Relative permeabilities for tap water and air, de-aired water and nitrogen were measured using a steady—state technique. Three different sand samples (fine sand, heterogeneous sand and coarse sand) were tested. 相似文献
6.
7.
An incremental iterative process based on direct energy minimization is presented for a limit analysis of nonlinear elastic lateral displacements and twists of reinforced and prestressed beams. Problems encountered with the constitutive relations are discussed and two possible material models are presented. 相似文献
8.
Crosslinking of tissue-derived biomaterials in 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) 总被引:2,自引:0,他引:2
J. M. Lee H. H. L. Edwards C. A. Pereira S. I. Samii 《Journal of materials science. Materials in medicine》1996,7(9):531-541
In contrast to bifunctional reagents such as glutaraldehyde or polyfunctional reagents such as polyepoxides, carbodiimides belong to the class of zero-length crosslinkers which modify amino acid side-groups to permit crosslink formation, but do not remain as part of that linkage. The authors have compared the effects of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and glutaraldehyde (the de facto industrial standard crosslinker) on the hydrothermal, biochemical, and uniaxial mechanical properties of bovine pericardium. EDC crosslinking was optimized for maximum increase in collagen denaturation temperature using variables of pH, concentration, and ratio of EDC to N-hydroxysuccinimide (NHS): a reagent for formation of activated esters. EDC and glutaraldehyde crosslinked materials were subjected to hydrothermal denaturation tests, biochemical degradation by enzymes (collagenase, trypsin) and CNBr, amino acid analysis for unreacted lysine, and to high strain rate mechanical tests including: large deformation stress-strain studies (0.1 to 10 Hz), stress relaxation experiments (loading time 0.1 s) and small deformation forced vibration (1 and 10 Hz). A protocol for EDC crosslinking was developed which used 1.15% EDC (2:1 EDC:NHS) at pH 5.5 for 24 h. The increase in denaturation temperature for EDC (from 69.7±1.2°C to 86.0±0.3°C) was equivalent to that produced by glutaraldehyde (85.3±0.4°C). Both treatments equivalently increased resistance to collagenase and CNBr degradation; however, after denaturation, the EDC-treated tissue was slightly more resistant to collagenase, and markedly more resistant to trypsin. EDC-treated materials were more extensible and more elastic than glutaraldehyde-treated materials. Despite the differences in crosslinking mechanism, EDC and glutaraldehyde-treated materials are very similar. Subtle but intriguing differences in biochemical structure remain to be investigated. 相似文献
9.
10.
A. Edwards Mulpuri V. Rao B. Molnar A. E. Wickenden W. Holland P. H. Chi 《Journal of Electronic Materials》1997,26(3):334-339
Doping by ion implantation using Si, O, Mg, and Ca has been studied in single crystal semi-insulating and n-type GaN grown
on a-sapphire substrates. The n-and p-type dopants used in this study are Si and O; Mg and Ca, respectively. Room temperature
activation of Si and O donors has been achieved after 1150°C annealing for 120 s. The activation of Mg and Ca acceptors is
too low to measure at both room temperature and 300°C. Using higher doses to achieve a measurable p-type conduction increases
the amount of damage created by the implantation. Rutherford back scattering measurements on this material indicate that the
damage is still present even after the maximum possible heat treatment. Secondary ion mass spectrometry measurements have
indicated a redistribution in the measured profiles of Mg due to annealing. 相似文献