全文获取类型
收费全文 | 13697篇 |
免费 | 1764篇 |
国内免费 | 519篇 |
专业分类
电工技术 | 983篇 |
综合类 | 724篇 |
化学工业 | 1319篇 |
金属工艺 | 192篇 |
机械仪表 | 326篇 |
建筑科学 | 1349篇 |
矿业工程 | 41篇 |
能源动力 | 4123篇 |
轻工业 | 132篇 |
水利工程 | 87篇 |
石油天然气 | 38篇 |
武器工业 | 11篇 |
无线电 | 3545篇 |
一般工业技术 | 2617篇 |
冶金工业 | 116篇 |
原子能技术 | 44篇 |
自动化技术 | 333篇 |
出版年
2024年 | 44篇 |
2023年 | 399篇 |
2022年 | 387篇 |
2021年 | 533篇 |
2020年 | 601篇 |
2019年 | 581篇 |
2018年 | 490篇 |
2017年 | 749篇 |
2016年 | 852篇 |
2015年 | 779篇 |
2014年 | 1091篇 |
2013年 | 989篇 |
2012年 | 1110篇 |
2011年 | 1476篇 |
2010年 | 861篇 |
2009年 | 798篇 |
2008年 | 656篇 |
2007年 | 667篇 |
2006年 | 564篇 |
2005年 | 398篇 |
2004年 | 298篇 |
2003年 | 256篇 |
2002年 | 222篇 |
2001年 | 183篇 |
2000年 | 155篇 |
1999年 | 109篇 |
1998年 | 153篇 |
1997年 | 83篇 |
1996年 | 95篇 |
1995年 | 43篇 |
1994年 | 72篇 |
1993年 | 59篇 |
1992年 | 33篇 |
1991年 | 20篇 |
1990年 | 26篇 |
1989年 | 13篇 |
1988年 | 16篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 18篇 |
1983年 | 9篇 |
1982年 | 15篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1975年 | 2篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
M.A.K. Lodhi 《Energy Conversion and Management》1996,37(12):1677-1694
Solar ponds are probably the simplest technology available for the useful conversion of solar energy. The basic technology is proven. Solar ponds have been shown to be technically feasible and economically viable for many applications, particularly for thermal use. The electrical conversion and use of solar energy via solar ponds is still questionable, in general, for economic viability. By putting the untapped sources together in the South Plains region, it looks promising economically both for thermal and electrical conversions and applications. There are a number of alkaline lake basins randomly scattered in the South Plains region of the U.S.A. In that area, there are thousands of crude oil producing wells that produce brine in abundance. The selection of suitable alkaline lake basins as a solar pond site and as depository sites of brine from oil wells and the using of this brine and salty water from alkaline lakes makes the solar pond economically viable for both thermal and electrical demands in the area. 相似文献
42.
不同光强下太阳电池组件曲线因数的研究 总被引:1,自引:0,他引:1
张剑 《有色金属材料与工程》2007,28(4):176-180
通过测试太阳电池组件在不同入射光强下的电性能参数,采用作拟合曲线的方法求解不同光强下太阳电池组件的曲线因数,并在此基础上分析组件曲线因数与入射光强的关系。 相似文献
43.
徐云生 《昆明理工大学学报(自然科学版)》1996,21(6):21-25
基于太阳辐射的光变特性和多层薄膜材料的变色效应,分析了新型太阳能节能窗对热候,冷候和温候空调的工作原理,重点讨论了可实现外加参量的动态调节透光性的薄膜材料的性能。 相似文献
44.
Joonyoung Park Sung-Hwan Han S. Senthilarasu Soo-Hyoung Lee 《Solar Energy Materials & Solar Cells》2007,91(8):751-753
Recent studies have reported that a thin interlayer between poly(3, 4-ethylene dioxythiophene)-poly(styrene sulfonic acid) (PEDOT: PSS) and an emissive polymer layer leads to a large increase in the performances of polymer light-emitting diodes (PLEDs) by preventing significant quenching of the radiative excitons at the PEDOT: PSS interface; therefore, acting as an efficient exciton-blocking layer. Using the similar idea, a thin interlayer was fabricated between PEDOT: PSS and the active layer of conjugated polymers/methanofullerene composites in a plastic solar cell. The interlayer consisted of a poly(fluorene)-based hole transporter spin-coated directly on top of the PEDOT: PSS layer. The devices with the interlayer exhibited a higher efficiency than in those without the interlayer. 相似文献
45.
姚夫森 《天津城市建设学院学报》2007,13(2):119-122
介绍了一种动静结合的软土路基沉降计算新方法,并将该方法应用到动力固结路基处理工程实践中.对软土路基沉降进行了计算,通过将沉降计算值与实测值进行比较,验证计算方法的可行性.计算结果显示,路基断面总沉降量计算值为669.6 mm,实测值为675 mm,两者比较相近,说明该沉降计算方法是可行的. 相似文献
46.
P. Lutsyk J. Misiewicz A. Podhorodecki Ya. Vertsimakha 《Solar Energy Materials & Solar Cells》2007,91(1):47-53
The optical and photovoltaic properties of dichlorotin phthalocyanine (SnCl2Pc) films and SnCl2Pc/pentacene (Pn) heterostructures (HS) have been studied. Weak bands at 1.35, 1.52 and 2.05 eV have been found in absorption and modulated photoreflectance spectra of SnCl2Pc films. These bands can be caused by the formation of charge transfer states. The low concentration of recombination centers of charge carriers has been formed on a free surface of SnCl2Pc films. This concentration essentially decreases at air evacuation before vacuum deposition of a Pn layer. Therefore, interface with an insignificant recombination rate of charge carriers is formed for SnCl2Pc/Pn HS. 相似文献
47.
太阳能热利用的现状和发展 总被引:2,自引:0,他引:2
开发利用新能源,尤其是太阳能,对人类环境的改善和社会的发展具有重要的战略意义。综述了国内外在太阳能热利用方面的现状及发展前景 相似文献
48.
Open sun drying has lost its previous importance due to the fact that different factors affect its reliability and the quality of the products obtained.
One of the set-backs for the analysis of solar drying exoeriments is their deoendence on a non-controlled source of energy, i.e. solar radiation depends on climatic conditions and experiments are difficult to compare. It is thus necessary to investigate the advantages of a particular set up as well as the climatic influences. Open sun drying could constitute the natural reference, allowing the comparison of different drying strategies.
A new way of standardizing drying times, based on solar radiation inout, is proposed, to allow better evaluation of the experiments. An equivalent time is defined, allowing comparison of experiments carried out under different circumstances. Carrots and potatoes were used in these experiments.
The use of the average daily solar radiation 15.28 MJ m-2.d-1 in Palma de Mallorca (39.33°N, 2.37°E), is proposed for comparison purposes. An improvement of more than 12 % in the explained variance was observed, the unexplained variance being lower than 1 %. 相似文献
One of the set-backs for the analysis of solar drying exoeriments is their deoendence on a non-controlled source of energy, i.e. solar radiation depends on climatic conditions and experiments are difficult to compare. It is thus necessary to investigate the advantages of a particular set up as well as the climatic influences. Open sun drying could constitute the natural reference, allowing the comparison of different drying strategies.
A new way of standardizing drying times, based on solar radiation inout, is proposed, to allow better evaluation of the experiments. An equivalent time is defined, allowing comparison of experiments carried out under different circumstances. Carrots and potatoes were used in these experiments.
The use of the average daily solar radiation 15.28 MJ m-2.d-1 in Palma de Mallorca (39.33°N, 2.37°E), is proposed for comparison purposes. An improvement of more than 12 % in the explained variance was observed, the unexplained variance being lower than 1 %. 相似文献
49.
50.
为了提高太阳辐照绝对辐射计(SIARs)的测量精度,消除温度变化对SIARs测量精度的影响,研究设计了精密温度控制系统,对SIARs进行恒温控制;通过对铂电阻温度传感器自热效应的弱化,提高了温度测量的精度;提出了一种新的复合PID控制算法,该复合控制算法使系统获得良好的动态和稳态性能;使用密闭的高低温箱来模拟星上温度条件对系统进行了实验测试,实验数据表明,系统控制精度在0.1℃以内,可为SIARs工作提供稳定的温度环境。 相似文献