全文获取类型
收费全文 | 9305篇 |
免费 | 346篇 |
国内免费 | 18篇 |
专业分类
电工技术 | 104篇 |
综合类 | 9篇 |
化学工业 | 2102篇 |
金属工艺 | 256篇 |
机械仪表 | 188篇 |
建筑科学 | 342篇 |
矿业工程 | 28篇 |
能源动力 | 211篇 |
轻工业 | 789篇 |
水利工程 | 112篇 |
石油天然气 | 38篇 |
武器工业 | 2篇 |
无线电 | 668篇 |
一般工业技术 | 1752篇 |
冶金工业 | 1943篇 |
原子能技术 | 62篇 |
自动化技术 | 1063篇 |
出版年
2023年 | 63篇 |
2022年 | 112篇 |
2021年 | 182篇 |
2020年 | 145篇 |
2019年 | 138篇 |
2018年 | 189篇 |
2017年 | 174篇 |
2016年 | 188篇 |
2015年 | 142篇 |
2014年 | 232篇 |
2013年 | 506篇 |
2012年 | 405篇 |
2011年 | 518篇 |
2010年 | 337篇 |
2009年 | 365篇 |
2008年 | 433篇 |
2007年 | 427篇 |
2006年 | 344篇 |
2005年 | 314篇 |
2004年 | 284篇 |
2003年 | 247篇 |
2002年 | 262篇 |
2001年 | 118篇 |
2000年 | 128篇 |
1999年 | 131篇 |
1998年 | 163篇 |
1997年 | 147篇 |
1996年 | 157篇 |
1995年 | 140篇 |
1994年 | 141篇 |
1993年 | 159篇 |
1992年 | 118篇 |
1991年 | 107篇 |
1990年 | 131篇 |
1989年 | 107篇 |
1988年 | 83篇 |
1987年 | 129篇 |
1986年 | 99篇 |
1985年 | 127篇 |
1984年 | 124篇 |
1983年 | 131篇 |
1982年 | 104篇 |
1981年 | 93篇 |
1980年 | 77篇 |
1979年 | 74篇 |
1978年 | 94篇 |
1977年 | 71篇 |
1976年 | 74篇 |
1975年 | 80篇 |
1974年 | 82篇 |
排序方式: 共有9669条查询结果,搜索用时 15 毫秒
11.
12.
Kruk Menno R.; Halász József; Meelis Wout; Haller József 《Canadian Metallurgical Quarterly》2004,118(5):1062
Aggressive behavior induces an adrenocortical stress response, and sudden stressors often precipitate violent behavior. Experiments in rats revealed a fast, mutual, positive feedback between the adrenocortical stress response and a brain mechanism controlling aggression. Stimulation of the aggressive area in the hypothalamus rapidly activated the adrenocortical response, even in the absence of an opponent and fighting. Hypothalamic aggression, in turn, was rapidly facilitated by a corticosterone injection in rats in which the natural adrenocortical stress response was prevented by adrenalectomy. The rapidity of both effects points to a fast, mutual, positive feedback of the controlling mechanisms within the time frame of a single conflict. Such a mutual facilitation may contribute to the precipitation and escalation of violent behavior under stressful conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
13.
Akhlesh Lakhtakia Joseph A. Sherwin 《Journal of Infrared, Millimeter and Terahertz Waves》2003,24(1):19-23
The potential of orthorhombic materials for perfect lenses is theoretically examined. 相似文献
14.
We create a business as usual scenario for office equipment electricity use from industry forecasts of equipment sales, surveys of equipment densities by building type, measured data on wattage and usage by equipment type and projected lifetimes for equipment. We then calculate electricity used by building type and equipment type for Energy Star and advanced scenarios and explore the sensitivity of these results to variations in key input parameters. According to our analysis, the Energy Star programme will save the US almost US$1 billion annually starting in the year 2000, with minimal expenditure of public funds. 相似文献
15.
Joseph Judenberg 《Information Systems Management》1994,11(4):34-38
Appropriately structured arrangements for systems maintenance outsourcing can yield significant benefits to many organizations. This article reviews methods for assessing potential maintenance outsourcing suppliers, for defining service criteria, and for evaluating contract terms. 相似文献
16.
Cynicism and Social Trust in the New Media Environment 总被引:1,自引:0,他引:1
Joseph N. Cappella 《The Journal of communication》2002,52(1):229-241
This article, with minor modifications, was the author's presidential speech to the International Communication Association conference, May 2001. It summarizes trends in social trust, trust in government, media, and other social institutions and evaluates the news and entertainment media's roles in these trends. Alternatives to causal accounts are proposed, including variations on genetic or "memetic" forms of explanation for media influences on macrosocial trends. 相似文献
17.
Joseph A Wehrmeyer Zhongxian ChengDavid M Mosbacher Robert W PitzRobin Osborne 《Combustion and Flame》2002,128(3):232-241
Several opposed jet flames, produced by a lean H2-air jet opposing a rich or lean C3H8-air jet, are investigated. Spontaneous Raman spectroscopy is used for major species concentration and temperature measurements along the opposed jet centerline. The hot products of the H2-air flame simulate the burnt gases of strong-burning near-stoichiometric reactants as they impinge upon a weak-burning lean or rich hydrocarbon-fueled reactant mix, a situation encountered in stratified charge operation of direct injection spark ignition engines. In addition the H2-air flame hot products facilitate experimental data interpretation through the absence of carbon-bearing species. Good agreement between numerical and experimental data are obtained for a rich (equivalence ratio, φ = 1.25) C3H8-air jet versus a lean (φ = 0.4) H2-air jet. Two lean C3H8-air jets (φ = 0.64 or 0.60), versus the φ = 0.4 H2-air jet, are also investigated. For both of these flames, the amount of CO2 production strongly depends upon φ, with the φ = 0.64 flame having a peak CO2 mole fraction an order of magnitude higher than for the φ = 0.60 flame, and the C3H8 flames burning either as a normal flame (high CO2) or as a “negative flame speed” flame producing little CO2 and then only through diffusion of C3H8 into the hot products jet. The numerically predicted and experimental CO2 profiles agree well for the positive flame speed flame, but the large discrepancy between predicted and measured peak CO2 in the negative flame speed flame suggests modeling improvements are needed for this type of flame. 相似文献
18.
A. T. Joseph 《Expert Systems》1991,8(2):119-127
ProKappa is an expert system tool kit developed by IntelliCorp in C using X-Windows for graphical interface. The SUN 3 or 4 version costs $9995/£7000 and $2595/£1800 for the interactive C environment.
This review covers ProKappa version 1.1, installed on a colour SUN SPARC Station 1 with the minimum recommended values of 12 Mb of memory and 30 Mb of swap space.
IntelliCorp can be contacted in the USA at 1975 El Camino Real West, Mountain View, CA 94040-2216 (+1 (415) 965-5500) and in the UK at 10 Jewry Street, Winchester, Hampshire SO23 8RZ (+44 (0)962 735348). 相似文献
This review covers ProKappa version 1.1, installed on a colour SUN SPARC Station 1 with the minimum recommended values of 12 Mb of memory and 30 Mb of swap space.
IntelliCorp can be contacted in the USA at 1975 El Camino Real West, Mountain View, CA 94040-2216 (+1 (415) 965-5500) and in the UK at 10 Jewry Street, Winchester, Hampshire SO23 8RZ (+44 (0)962 735348). 相似文献
19.
We consider the switchbox routing problem of two-terminal nets in the case when all thek nets lie on two adjacent sides of the rectangle. Our routing model is the standard two-layer model. We develop an optimal algorithm that routes all the nets whenever a routing exists. The routing obtained uses the fewest possible number of vias. A more general version of this problem (adjacent staircase) is also optimally solved.This research was supported in part by NSA Contract No. MDA-904-85H-0015, NSF Grant No. DCR-86-00378, and by NSF Engineering Research Centers Program NSFD CDR 88003012. 相似文献
20.
Atmospheric corrosion of reference metals in Antarctic sites 总被引:1,自引:0,他引:1
Manuel Morcillo Beln Chico Daniel de la Fuente Elisabete Almeida Günter Joseph Susana Rivero Blanca Rosales 《Cold Regions Science and Technology》2004,40(3):165-178
This paper presents the results obtained at three Antarctic test sites participating in the “Ibero-American Map of Atmospheric Corrosiveness” (MICAT), a project on atmospheric corrosion carried out during the period 1988–1994 at some 70 sites distributed across 12 countries of the Latin-American region, Spain and Portugal. The three Antarctic sites are located near the coastline.The singular climatic characteristics of Antarctic regions are related with the purity of the air, the absence of rainfall and the formation of ice on the metallic surface during an important part of the exposure time. However, electrochemical activity is possible below ice layers. This situation affects the structure and morphology of corrosion product films and the resulting corrosion rates of metallic surfaces. 相似文献