全文获取类型
收费全文 | 89875篇 |
免费 | 7608篇 |
国内免费 | 2850篇 |
专业分类
电工技术 | 3749篇 |
技术理论 | 4篇 |
综合类 | 6368篇 |
化学工业 | 20407篇 |
金属工艺 | 9074篇 |
机械仪表 | 3307篇 |
建筑科学 | 11946篇 |
矿业工程 | 2504篇 |
能源动力 | 9218篇 |
轻工业 | 6305篇 |
水利工程 | 2235篇 |
石油天然气 | 3776篇 |
武器工业 | 424篇 |
无线电 | 2184篇 |
一般工业技术 | 8678篇 |
冶金工业 | 7379篇 |
原子能技术 | 1268篇 |
自动化技术 | 1507篇 |
出版年
2024年 | 343篇 |
2023年 | 1005篇 |
2022年 | 2252篇 |
2021年 | 2591篇 |
2020年 | 2629篇 |
2019年 | 2001篇 |
2018年 | 1904篇 |
2017年 | 2305篇 |
2016年 | 2626篇 |
2015年 | 2764篇 |
2014年 | 5141篇 |
2013年 | 5087篇 |
2012年 | 6200篇 |
2011年 | 6658篇 |
2010年 | 5252篇 |
2009年 | 5498篇 |
2008年 | 4265篇 |
2007年 | 5921篇 |
2006年 | 5531篇 |
2005年 | 4871篇 |
2004年 | 4194篇 |
2003年 | 3815篇 |
2002年 | 3343篇 |
2001年 | 2624篇 |
2000年 | 2155篇 |
1999年 | 1729篇 |
1998年 | 1353篇 |
1997年 | 1188篇 |
1996年 | 925篇 |
1995年 | 824篇 |
1994年 | 625篇 |
1993年 | 506篇 |
1992年 | 453篇 |
1991年 | 308篇 |
1990年 | 229篇 |
1989年 | 252篇 |
1988年 | 171篇 |
1987年 | 139篇 |
1986年 | 106篇 |
1985年 | 88篇 |
1984年 | 114篇 |
1983年 | 88篇 |
1982年 | 71篇 |
1981年 | 17篇 |
1980年 | 17篇 |
1979年 | 11篇 |
1966年 | 9篇 |
1964年 | 9篇 |
1959年 | 34篇 |
1951年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Preparation of Plate Fe_(60)Co_8Zr_(10)Mo_5W_2B_(15) Bulk Amorphous Alloy and Its Fracture Toughness
肖华星 《武汉理工大学学报(材料科学英文版)》2005,20(2)
1Introduction Duwez[1]synthesizedthefoilAu Siamorphousalloyforthefirsttimewithrapidsolidification,whichinitiatedthepreparationofamorphousalloysintheprocessofalloysolidification,andthereaftertheresearchonamorphousal loysdevelopedrapidly.Since1980s,withthec… 相似文献
32.
33.
我国风机盘管技术现状分析 总被引:2,自引:2,他引:0
介绍了近年来我国在风机盘管技术领域的最新成果,在结构形式、强化传热、提高室内空气品质、降低噪音和提高自动控制水平等方面的技术进展情况,分析了目前风机盘管中存在的问题,并对今后的发展方向进行了展望。 相似文献
34.
分析了电石法PVC生产链中电石炉烟气及电厂烟气二氧化硫的排放情况,指出利用电石炉烟气中的CO合成氨、再将合成氨用于燃煤电厂烟气的"氨法"脱硫是具有较大应用潜力的循环经济产业链。 相似文献
35.
The main components of thermophotovoltaic (TPV) devices are the primary lens (or mirror), the absorber, the PV cell, and a photon recuperator system. A theory integrating all these components is used in this paper to analyse a particular type of TPV device (plane disk absorber and PV cell). The TPV efficiency is maximized by using three optimization parameters, namely absorber, PV cell temperatures, and cell voltage. Almost ideal operation conditions are envisaged and upper bounds are obtained for the TPV efficiency. They are strongly dependent on PV cell bandgap and radiation concentration. Preliminary results suggest the existence of an optimum solar radiation concentration ratio. The improvement in thermal design quality allows the usage of PV cells based on wide bandgap semiconductors. 相似文献
36.
裂齿矩形翅片板翅式换热器优化设计的分析 总被引:2,自引:0,他引:2
对裂齿矩形翅片板翅式换热器中的裂齿矩形翅片的传热效率作了分析,并以单位质量材耗的换热能力最大为目标函数,分析研究了在不同雷诺数(Re)的操作条件下裂齿矩形翅片间角度、翅片厚、长度、宽度及极厚之间的关系。结果表明:在气体换热的场合下,当Re在某一范围时翅片可有效地起到强化传热的作用。当板厚为5mm,翅片厚为3mm,翅片间夹角为45°~70°,Re为2×10~3~8×10~3,最佳翅片纵向间距与翅片长度和翅片厚度乘积的平方根的比为1.5~2.5,最佳翅片尺寸系数为3~5时,传热强化效果较好。 相似文献
37.
The effect of pressure on combustion and heat transfer is analyzed. The research is based on the basic combustion and heat
transfer theorem. A correction for the heat calculation method for pressurized furnace is made on the basis of the normal
pressure case. The correction takes the effect of pressurizing into account. The results show that the correction is reasonable
and the method is applicable to combustion and heat transfer of the marine supercharged boiler. 相似文献
38.
Critical heat fluxes (CHFs) were measured for two types of rectangular ducts containing horizontal flat plate heaters. One has the flat plate heater of 6 mm wide and 20 mm long located on the inner lower wall at 50 mm from the inlet. The other duct has two horizontal flat plates of 6 mm wide and 20 mm long on inner upper and lower walls at 50 mm from the inlet. The equation of CHF for the forced convection containing a new nondimensional-parameter m introduced in order to calculate cross-sectionally averaged liquid temperature at the center of the duct was derived based on two fluid model, ordinary convection theorem and experimental results. It was confirmed that this correlation can describe not only the author's data on the duct but also other worker's data for channels with different shapes and sizes. 相似文献
39.
A. F. Kurbatskii 《High Temperature》2004,42(1):79-87
The difference in the turbulent diffusion between the active (heat) and passive (mass) scalars in a thermally stably stratified medium is investigated. The axisymmetric problem is treated on the formation of a turbulent circulation flow above a heated disk and on the turbulent diffusion of a passive scalar (impurity) from a continuous surface source in a stably stratified medium. The results indicate that the thermal stratification causes appreciable differences in the coefficients of turbulent transfer between the active (heat) and passive (mass) scalars. This means that the assumption of the identity of the coefficient of turbulent diffusion of heat and mass, employed in conventional models of turbulence, produces significant errors in estimating the heat and mass transfer in a thermally stably stratified medium. 相似文献
40.
John E. Sohn 《The Journal of Adhesion》1985,19(1):15-27
Enhanced matrix-filler adhesion is realized after filler treatment with a surface treatment process. The hydrosol/coupling agent treatment was applied to a wide range of inorganic and organic fillers, and adhesion to a variety of matrix resins was improved. Scanning Electron Microscopy (SEM) was used to determine the locus of failure in the filled systems. The locus of failure shows the relative degree of adhesion between the filler and the polymer matrix. Significant improvement in adhesion in humid environments is also observed. 相似文献