全文获取类型
收费全文 | 14660篇 |
免费 | 1309篇 |
国内免费 | 771篇 |
专业分类
电工技术 | 942篇 |
技术理论 | 6篇 |
综合类 | 1524篇 |
化学工业 | 2365篇 |
金属工艺 | 292篇 |
机械仪表 | 539篇 |
建筑科学 | 2775篇 |
矿业工程 | 834篇 |
能源动力 | 745篇 |
轻工业 | 838篇 |
水利工程 | 1166篇 |
石油天然气 | 436篇 |
武器工业 | 137篇 |
无线电 | 511篇 |
一般工业技术 | 1209篇 |
冶金工业 | 872篇 |
原子能技术 | 132篇 |
自动化技术 | 1417篇 |
出版年
2024年 | 54篇 |
2023年 | 240篇 |
2022年 | 443篇 |
2021年 | 562篇 |
2020年 | 520篇 |
2019年 | 450篇 |
2018年 | 387篇 |
2017年 | 415篇 |
2016年 | 438篇 |
2015年 | 436篇 |
2014年 | 1043篇 |
2013年 | 1110篇 |
2012年 | 1053篇 |
2011年 | 1085篇 |
2010年 | 903篇 |
2009年 | 886篇 |
2008年 | 776篇 |
2007年 | 1049篇 |
2006年 | 934篇 |
2005年 | 747篇 |
2004年 | 676篇 |
2003年 | 492篇 |
2002年 | 428篇 |
2001年 | 338篇 |
2000年 | 277篇 |
1999年 | 211篇 |
1998年 | 128篇 |
1997年 | 123篇 |
1996年 | 87篇 |
1995年 | 80篇 |
1994年 | 67篇 |
1993年 | 42篇 |
1992年 | 42篇 |
1991年 | 29篇 |
1990年 | 28篇 |
1989年 | 23篇 |
1988年 | 20篇 |
1987年 | 12篇 |
1986年 | 10篇 |
1985年 | 17篇 |
1984年 | 6篇 |
1983年 | 12篇 |
1982年 | 23篇 |
1981年 | 3篇 |
1979年 | 7篇 |
1965年 | 3篇 |
1964年 | 3篇 |
1961年 | 3篇 |
1958年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
J. Schanda 《Color research and application》2007,32(3):233-235
This is a comment to the editorial by J. Hutchings on “Talking about Color… and Ethics.” © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 233–235, 2007 相似文献
52.
53.
54.
Thomachan.A. Kattakayam Sumanta Khan Kandadai Srinivasan 《Solar Energy Materials & Solar Cells》1996,44(1):25
This article describes the development of an instrumentation system for characterizing photovoltaic panels. It uses an add on card (which contains DAC, ADC and digital input/output ports) in conjunction with a PC-AT. The panels in a field are selected in succession through a set of relays actuated by the digital output port. The selected panel is loaded in discreet steps by a transistor loading circuit which is activated by the digital to analog convertor to trace the most significant portion of the I-V curve. The data shows that the power output is invariably lower than that specified by the manufacturer. The reasons for drop in output have been analyzed. It is shown that these effects can be represented by the curvature of I-V characteristic at the maximum power point (OP). The loss of power due to accumulation of dust and the increase in temperature of the panels can be significant. 相似文献
55.
The European Commission has been requested by member states to study the incorporation of air transport into their existing emissions trading scheme (ETS). Only CO2 is to be included, at least initially. 相似文献
56.
57.
Fatigue at high temperature is a complex phenomenon as it is influenced by a number of time-dependent processes which become
important at elevated temperatures. These processes include creep, oxidation, phase instabilities and dynamic strain ageing
(DSA), acting either independently or synergistically influence fatigue behaviour, often lowering the fatigue life. Current
design approaches employ linear summation of fatigue and creep damage with suitable factors on permissible damage to take
care of uncertainties in interaction between cyclic and time-dependent processes. It is, therefore, important to develop a
deeper understanding of the processes that occur during high temperature fatigue so that realistic life predictions could
be made.
Results on the high temperature fatigue behaviour of austenitic stainless steels, ferritic steels and nickel base alloys are
presented here. The important mechanisms of interaction of high temperature time-dependent processes with fatigue under various
conditions are discussed in detail. Emphasis is placed on cyclic stress response, fatigue life, deformation substructure and
fracture behaviour. This is followed by a review of important life prediction techniques under combined creep-fatigue loading
conditions. Life prediction techniques considered here include linear damage summation, strain range partitioning, ductility
exhaustion approach, frequency modified and frequency separation methods, techniques based on hysteresis energy and damage
rate models, and methods based on crack-cavitation interation models. 相似文献
58.
环境伴随着经济的发展越来越体现了它的重要性,全社会应重视环境、保护环境,以预防为主,加强综合治理,使我们的天更蓝、水更净、草更绿,到处充满着春的意境. 相似文献
59.
The rapid growth of Chinese economy has tremendously stimulated the expansion of energy consumption. The structure of energy consumption in China is featured with the coal domination. Air pollution is becoming increasingly severe. As a result, we are confronted with the extremely arduous task to balance energy consumption and environmental protection. In order to coordinate the relationship between energy consumption and environmental protection in a strategic way, this paper analyzes comprehensively the instruments, effects and perspectives of energy-related environmental management. Meanwhile, this paper illustrates the barriers and challenges facing the energy and energy-related environmental management in China, and suggests a priority strategy of management instrument, mainly composed of energy-saving, optimization of energy structure, promulgation of environmental standards, advance in environmental technologies, internalization of environmental costs, establishment of a public benefit fund and adoption of a Renewable Portfolio System. 相似文献
60.
ZigBee作为当前主流的无线传感网技术,具有成本低廉、组网便捷、扩展灵活等特点。文章提出将ZigBee技术应用于粮仓环境监测系统中,相比有线粮仓环境监控系统,可以提高灵活性和可靠性。该系统结合CC1101无线传输模块和STC89C52控制器实现对各传输节点的软硬件设计。实现了环境参数的自动采集、无线传输,在协调器节点汇总的数据可以交由控制中心实现对数据的实时分析。 相似文献