全文获取类型
收费全文 | 17840篇 |
免费 | 2990篇 |
国内免费 | 1066篇 |
专业分类
电工技术 | 121篇 |
综合类 | 1416篇 |
化学工业 | 10108篇 |
金属工艺 | 844篇 |
机械仪表 | 213篇 |
建筑科学 | 639篇 |
矿业工程 | 980篇 |
能源动力 | 872篇 |
轻工业 | 1434篇 |
水利工程 | 195篇 |
石油天然气 | 1361篇 |
武器工业 | 44篇 |
无线电 | 214篇 |
一般工业技术 | 1915篇 |
冶金工业 | 960篇 |
原子能技术 | 379篇 |
自动化技术 | 201篇 |
出版年
2024年 | 97篇 |
2023年 | 300篇 |
2022年 | 604篇 |
2021年 | 767篇 |
2020年 | 825篇 |
2019年 | 720篇 |
2018年 | 737篇 |
2017年 | 794篇 |
2016年 | 880篇 |
2015年 | 827篇 |
2014年 | 1065篇 |
2013年 | 1351篇 |
2012年 | 1681篇 |
2011年 | 1259篇 |
2010年 | 948篇 |
2009年 | 1020篇 |
2008年 | 768篇 |
2007年 | 1025篇 |
2006年 | 1017篇 |
2005年 | 714篇 |
2004年 | 651篇 |
2003年 | 566篇 |
2002年 | 472篇 |
2001年 | 393篇 |
2000年 | 378篇 |
1999年 | 277篇 |
1998年 | 248篇 |
1997年 | 234篇 |
1996年 | 199篇 |
1995年 | 148篇 |
1994年 | 177篇 |
1993年 | 133篇 |
1992年 | 117篇 |
1991年 | 93篇 |
1990年 | 64篇 |
1989年 | 60篇 |
1988年 | 52篇 |
1987年 | 50篇 |
1986年 | 28篇 |
1985年 | 34篇 |
1984年 | 30篇 |
1983年 | 21篇 |
1982年 | 15篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1959年 | 4篇 |
1951年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Copper phthalocyanine as corrosion inhibitor for ASTM A606-4 steel in 16% hydrochloric acid 总被引:2,自引:0,他引:2
A study based on the corrosion inhibition properties of copper phthalocyanine is described. Coverage degrees of copper phthalocyanine (Cu-phcy) on ASTM-A606-4 steel, obtained by weight loss measurements, were fitted to Langmuir, Frumkin, Temkin and Flory–Huggins adsorption isotherms. A better fit to the Langmuir isotherm was obtained. The polarization curves showed that polarization of both the anodic and cathodic reactions were verified for concentrations higher than 10–4 M, indicating a mixed type action. Only the anodic reactions were polarized for lower concentrations. At high frequencies the Nyquist diagrams showed one capacitive loop attributable to double layer charging and a small one at intermediary frequencies attributable to the faradaic process of hydrogen evolution. The formation of an adsorbed film was characterized by increasing charge transfer resistance values in the low frequency range for increasing inhibitor concentrations. According to the techniques used in this study, copper phthalocyanines showed a high corrosion inhibiting efficiency for all concentrations. 相似文献
62.
The effect of adsorption on the measurement of diffusion coefficients by the Taylor dispersion technique is investigated by modifying the governing equation to account for reversible, nonequilibrium adsorption. The resulting two-dimensional equations are solved by an explicit finite-difference technique. Experimental data for the acridine carbon dioxide system indicated that acridine adsorbs on the walls on the tubing and these data were investigated with this model. The influence of carious parameters including the number of sites and the rates of adsorption desorption was investigated by conducting a parametric sensitivity analysis on the model. It was found that adsorption of the solute on the wall of the tubing could produce an error as high as 35% on the measured diffusion coefficient compared to the actual diffusion coellicient. Examination of the influence of each of the parameters will enable Inure investigators to reduce the effect of adsorption in the measurement of diffusion coefficients by Taylor dispersion. 相似文献
63.
本文讨论了600~1200K范围内使用NaCl作为添加剂焙烧钒渣时氯化发镓的热力可靠性。结论是:氯氧比的大小与溶性钒酸钠生成有直接联系,NaCl和Na2O。V2O5平衡时的氯氧比最大;在氯化钠作用下,镓主要生成GaCl3挥发,计算得到的GaCl3的生成压相当大。 相似文献
64.
This paper deals with the application of continuous thermodynamics to light and heavy oil systems using the Peng- Robinson equation of state. The composition of the high molar mass components in a reservoir oil is described by a continuous distribution function of some characterizing quantity, e.g. molar mass or boiling temperature. Numerical Gaussian quadrature methods are used to generate pseudo-components and their mole fractions from distribution data. Several examples are presented for phase equilibria of solvent/crude oil systems. The results showed that semi-infinite distribution functions, such as the Γ function, cannot be applied to all cases, e.g. dew point calculations. The Gauss- Legendre quadrature method coupled with spline fitting worked best for heavy oil systems. 相似文献
65.
66.
The influence of irreversibility of finite-rate heat transfer on the performance of an absorption refrigerator is investigated using an endoreversible cycle model with continuous flow. The cooling rate is adopted as an objective function for refrigerator optimization. The maximum cooling rate and the corresponding coefficient of performance are derived. The optimal performance with respect to heat transfer areas of the refrigerator is analysed. In addition, certain significant conclusions are reached. 相似文献
67.
An analysis of the thermodynamics of epitaxy in thin films is presented which includes the effects of the surface stresses
of the free surface and the film-substrate interface. It is shown that these effects, which are usually ignored in the theory
of epitaxy, can have a major influence on both the critical thickness for epitaxy and on the partitioning of the misfit strain
between the volume elastic strain and interface dislocations. 相似文献
68.
本文测定了酒精中甲醇、水单组分及二元组分的吸附等温线,并用Langmuir方程进行了拟合。在固定床动态吸附研究申测定了酒精中甲醇、水单组分及双组分吸附穿透曲线;着重考察了流速、温度、不同甲醇和水含量对双组分吸附性能的影响。对二个组分的传质机理及置换关系进行了分析探讨。 相似文献
69.
70.