全文获取类型
收费全文 | 1885篇 |
免费 | 32篇 |
国内免费 | 22篇 |
专业分类
电工技术 | 10篇 |
综合类 | 29篇 |
化学工业 | 673篇 |
金属工艺 | 142篇 |
机械仪表 | 95篇 |
建筑科学 | 26篇 |
矿业工程 | 31篇 |
能源动力 | 315篇 |
轻工业 | 132篇 |
水利工程 | 7篇 |
石油天然气 | 13篇 |
武器工业 | 2篇 |
无线电 | 71篇 |
一般工业技术 | 281篇 |
冶金工业 | 68篇 |
原子能技术 | 14篇 |
自动化技术 | 30篇 |
出版年
2023年 | 15篇 |
2022年 | 27篇 |
2021年 | 29篇 |
2020年 | 35篇 |
2019年 | 34篇 |
2018年 | 35篇 |
2017年 | 54篇 |
2016年 | 46篇 |
2015年 | 58篇 |
2014年 | 114篇 |
2013年 | 226篇 |
2012年 | 72篇 |
2011年 | 133篇 |
2010年 | 117篇 |
2009年 | 105篇 |
2008年 | 80篇 |
2007年 | 101篇 |
2006年 | 105篇 |
2005年 | 81篇 |
2004年 | 76篇 |
2003年 | 60篇 |
2002年 | 64篇 |
2001年 | 43篇 |
2000年 | 37篇 |
1999年 | 49篇 |
1998年 | 18篇 |
1997年 | 24篇 |
1996年 | 23篇 |
1995年 | 18篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有1939条查询结果,搜索用时 15 毫秒
31.
B. Ouertani J. Ouerfelli M. Saadoun B. Bessaïs H. Ezzaouia J.C. Bernde 《Materials Characterization》2005,54(4-5):431-437
FeS2-thin films with good crystallinity were synthesized by a simple method which consists of sulphuration, under vacuum, of amorphous iron oxide thin films pre-deposited by spray pyrolysis of FeCl3·6H2O (0.03 M)-based aqueous solution onto glass substrates heated at 350 °C. At optimum sulphuration temperature (450 °C) and duration (6 h), black green layers having granular structure and high absorption coefficient (5.104 cm−1) were obtained. The study of the electrical properties of the as-prepared films vs. the temperature variations showed three temperature domain dependence of the conductivity behaviour. The first one corresponds to the high temperature range (330 K–550 K) for which an Arrhenius plot type was obtained. The activation energy value was estimated at about 61.47 meV. The second domain corresponding to the intermediate temperature range (80 K–330 K) showed a variable activation energy between the grain boundaries. The barrier height, q¯, was estimated to 27±0.5 meV, and the standard deviation, qσ, was evaluated at about 14±0.5 meV. We found that at lower temperatures (20 K–80 K), the conductivity is governed by two conduction types. The density of localised states, was about 2.45×1020 eV−1 cm−3. 相似文献
32.
Using photo acoustic technique, the thermal properties of CdS thin films grown by spray pyrolysis are measured. Thermal diffusivity
and conductivity in these films decrease at least two orders compared with bulk. These results are compared with our study
on nano CdS and the other available literature. The comparison is good. The dependence of thermal diffusivity on the thickness
of the layer or the size of the particles on the glass substrate are analysed from the present measurement and discussed.
The dependence of thermal diffusivity on the thickness of the layer on the glass substrate is discussed. 相似文献
33.
蒸发式冷凝器结构特点及工程应用 总被引:1,自引:0,他引:1
关朋 《制冷与空调(北京)》2004,4(2):63-66
本文对蒸发式冷凝器的结构、工作原理及安装、使用过程中应注意的问题作一下介绍.并结合工程实例,对蒸发式冷凝器和水冷式冷凝器作综合比较. 相似文献
34.
通过添加高分子分散剂配制Cr3C2-25%NiCr料浆,喷雾干燥制备出高球形化的Cr3C2-25%NiCr复合粉末。利用SEM研究了分散剂含量对喷雾干燥制备的Cr3C2-25%NiCr复合粉末性能的影响,结果表明:分散剂能够调节料浆性能,粉末的流动性及松装密度明显提高,其中0.04%含量的分散剂所制备的Cr3C2-25%NiCr粉末具有最佳的物理性能。 相似文献
35.
介绍泉州市泉港区广播电视大楼消防设计。结合实例探讨消防水池合理储水容积的确定 ;室内消火栓的正确布置 ;自动喷水灭火系统结合保护对象的不同特点 ,分别设计为闭式系统、雨淋系统、水喷雾系统 ;探讨消防系统的控制方式 ;自动喷水灭火系统管道的连接方式 ;气体消防灭火剂的选择等需要注意的几个问题 相似文献
36.
针对复杂自由曲面中直纹组合曲面上喷涂机器人喷枪轨迹优化及轨迹连接问题,基于曲面面片造型与智能算法理论,建立了喷枪轨迹优化数学模型,提出一种满足直纹曲面上喷枪轨迹首尾衔接的算法程序。首先,通过曲面特征定义直纹曲面,并对直纹曲面造型处理后建立复合喷涂直纹圆弧面片的喷枪数学模型;其次,选择直纹组合面片交界处的喷枪轨迹为优化对象,依据该模型对直纹曲面及直纹组合面片上的喷枪轨迹进行优化,验证了该模型的有效性;最后,依据轨迹优化模型,设计算法程序并通过仿真实验,验证了该算法程序的可行性与优越性,实现了对直纹组合曲面的连续性喷涂。 相似文献
37.
38.
ABSTRACT: Amaranthus betacyanin extracts were spray-dried using a range of maltodextrins [10-25 dextrose equivalent (DE)] and starches (native/modified) as carrier and coating agents at 5 inlet/outlet air temperatures and 4 feed solid contents. Higher inlet/outlet air temperatures caused greater betacyanin loss during spray drying, and affected slightly the pigment stability during storage. Adding maltodextrins and starches significantly reduced the hygroscopicity of the betacyanin extracts and enhanced storage stability. The 25 DE/10 DE mixed powders provided a longer predicted half-life (63.6 wk) compared to the 25 DE and the 10 DE powders separately. The best dried pigment-containing powder made was superior to commercial red beet powder in physical properties. 相似文献
39.
0INTRODUCTIONSinceDuwezproducedfirstlyglassyAu-Sialloybyrapidquenchingtechniqueinl96o['],rapidsolidificationtechnologyhasmadegreatprogress.Nowadaysanumberofrapidsolidificationmethodshavebeenusedtopro-ducerapidlysolidifiedmaterialssuchaspow-der,ribbon,foilandwirel'].ThesetechniquesareabletoachievecoolingratetotheorderoflO'~lO't/s,yieldingexcellentlyrefinedandhomogeneousmicrostrllcturewithre-sultantoutstandingmechanifPl,physicalandchemicalpropertiesl"'].Althoughprominentimprovementsinprop… 相似文献
40.
《Advanced Powder Technology》2021,32(11):4167-4176
Hexagonal Boron nitride nanoplatelet (BNNP) with the combination of excellent mechanical properties, high-temperature thermal stability, and self-lubrication is a promising strengthening agent in plasma-sprayed composite coatings. However, it is a significant challenge to produce plasma sprayable feedstocks with homogeneously dispersed BNNPs owing to the intrinsic agglomeration of BNNPs. In this research, three powder preparation processes (electrostatic interaction, ball milling, and shear mixing) were employed to disperse BNNPs in Ni-Cr-Cr2O3 (NCCO) powders. The shear mixing process presents a competitive advantage in powder preparation, providing stable shear force and achieving exfoliated BNNPs homogeneous distribution in the composite powders. The spray drying technique was finally utilized to obtain spherical agglomerated BNNP-NCCO feedstocks with characteristics of relatively smooth surface and uniform size distribution. Hence, shear mixing and spray drying processes are expected to produce large-scale spherical composite powders with a homogeneous distribution of 2D layered nanomaterials for industrial application. 相似文献