全文获取类型
收费全文 | 1643篇 |
免费 | 109篇 |
国内免费 | 45篇 |
专业分类
电工技术 | 32篇 |
综合类 | 62篇 |
化学工业 | 565篇 |
金属工艺 | 25篇 |
机械仪表 | 39篇 |
建筑科学 | 98篇 |
矿业工程 | 9篇 |
能源动力 | 171篇 |
轻工业 | 94篇 |
水利工程 | 17篇 |
石油天然气 | 49篇 |
武器工业 | 9篇 |
无线电 | 45篇 |
一般工业技术 | 464篇 |
冶金工业 | 22篇 |
原子能技术 | 20篇 |
自动化技术 | 76篇 |
出版年
2024年 | 3篇 |
2023年 | 18篇 |
2022年 | 34篇 |
2021年 | 36篇 |
2020年 | 34篇 |
2019年 | 35篇 |
2018年 | 38篇 |
2017年 | 41篇 |
2016年 | 48篇 |
2015年 | 34篇 |
2014年 | 56篇 |
2013年 | 134篇 |
2012年 | 58篇 |
2011年 | 83篇 |
2010年 | 68篇 |
2009年 | 69篇 |
2008年 | 79篇 |
2007年 | 79篇 |
2006年 | 67篇 |
2005年 | 75篇 |
2004年 | 51篇 |
2003年 | 78篇 |
2002年 | 60篇 |
2001年 | 42篇 |
2000年 | 33篇 |
1999年 | 47篇 |
1998年 | 29篇 |
1997年 | 34篇 |
1996年 | 34篇 |
1995年 | 38篇 |
1994年 | 26篇 |
1993年 | 25篇 |
1992年 | 22篇 |
1991年 | 25篇 |
1990年 | 25篇 |
1989年 | 28篇 |
1988年 | 20篇 |
1987年 | 22篇 |
1986年 | 27篇 |
1985年 | 13篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有1797条查询结果,搜索用时 15 毫秒
991.
A.?AliEmail author A.?K.?Nain B.?Lal D.?Chand 《International Journal of Thermophysics》2004,25(6):1835-1847
The densities, , viscosities, , and refractive indices, n, of binary mixtures of benzene with 1-butanol, 2-methyl-1-propanol, 2-butanol, and 2-methyl-2-propanol, including those of the pure liquids, were measured over the complete composition range at 30°C. The dependence of , , and n on composition was checked by using an empirical relation. The experimental data were used to calculate excess molar volumes, VE, deviations in viscosity, , excess free energies of activation of viscous flow, G*E, deviations in refractive index, n, apparent molar volumes, V,1 and V, 2, and partial molar volumes,
, of benzene in alcohols and alcohols in benzene, respectively, at infinite dilution. The variations of these parameters with composition and the effect of branching in alcohols were discussed from the point of view of intermolecular interactions in these mixtures. 相似文献
992.
B. S. Seplyarskii T. P. Ivleva E. A. Levashov 《Combustion, Explosion, and Shock Waves》2004,40(3):302-310
The dynamics of coating production using a reaction mixture with thermoreactive electricspark strengthening is studied numerically. It is shown that the main parameter that determines the thermal regime of coating is the initial thickness of the mixture layer. The parameter ranges for the process in a combustion regime and in a quasivolume conversion regime are determined. The effect of discharge frequency and the thermal characteristics of the reaction mixture and the substrate being strengthened on coating time is investigated. It is established that for a particular reaction mixture, the characteristic conversion temperature can be controlled by varying the electric discharge power and, hence, the heat flux at the active stage of the process, and for coating formation at this characteristic temperature, it is necessary that the thickness of the active layer be lower than a certain critical value. 相似文献
993.
994.
实时混叠是混叠类型中最简单的一种,也是迄今为止最为常见的一种。本文介绍了实时混叠盲源分离的数学模型和算法原理,深入研究了常态情形的盲分离算法,其中包括批处理法和自适应法。以自适应法中的顺序提取法为重点,介绍了运用FastICA分离方法的3组实验仿真结果,证明了这种算法的可行性和有效性。 相似文献
995.
根据Superpave推广应用现状,简要介绍了该技术的特点及优势,并结合Superpave技术在内蒙古自治区内应用研究的成果,论证了该技术在穿沙高速公路建设中的广阔应用前景。 相似文献
996.
A novel method for obtaining the distribution functions from the Boltzmann equations for binary granular gas mixtures of smooth
spheres has been developed. The method is capable of producing accurate results irrespective of the values of the parameters
which define the system. Here we explain the method and present results obtained using it for the temperature ratio of the
components, as well as for the flatness (and higher order measures of flatness) of the distribution functions, for the homogeneous
cooling state. It turns out that the mean field approximation for the temperature ratio yields results which are within about
1% or better of the exact results for all checked values of the parameters (except when the mass ratio is very large (or small)
and the system is very inelastic) even when the values of the flatness suggest that the distribution functions are not near-Maxwellian.
The use of the method for obtaining constitutive relations is outlined but detailed results are deferred to another publication. 相似文献
997.
998.
M. LONGFILS M. RÖDING A. ALTSKÄR E. SCHUSTER N. LORÉN A. SÄRKKÄ M. RUDEMO 《Journal of microscopy》2018,269(3):269-281
Recently we complemented the raster image correlation spectroscopy (RICS) method of analysing raster images via estimation of the image correlation function with the method single particle raster image analysis (SPRIA). In SPRIA, individual particles are identified and the diffusion coefficient of each particle is estimated by a maximum likelihood method. In this paper, we extend the SPRIA method to analyse mixtures of particles with a finite set of diffusion coefficients in a homogeneous medium. In examples with simulated and experimental data with two and three different diffusion coefficients, we show that SPRIA gives accurate estimates of the diffusion coefficients and their proportions. A simple technique for finding the number of different diffusion coefficients is also suggested. Further, we study the use of RICS for mixtures with two different diffusion coefficents and investigate, by plotting level curves of the correlation function, how large the quotient between diffusion coefficients needs to be in order to allow discrimination between models with one and two diffusion coefficients. We also describe a minor correction (compared to published papers) of the RICS autocorrelation function. 相似文献
999.
CO2混合工质兼顾高效和环境友好的特点,在新一代热功转化循环中受到广泛关注。混合工质气液相平衡性质是循环分析与计算的基础。为了提高CO2混合工质气液相平衡数据的计算精度,采用PR状态方程结合三种混合规则(vdW、MHV1、WS),对7种CO2+HFCs/HFOs及4种CO2+HCs混合工质的气液相平衡性质进行了计算。结果表明,对CO2+HCs混合工质,vdW混合规则可达较好的结果;对CO2+HFCs/HFOs混合工质,在亚临界区三者计算精度相近,但在超临界区,WS混合规则对计算精度提升明显。最后,提出了一种差值模型预测CO2混合工质气液相平衡性质,预测的AARD(p)值为2.03%,AAD(y)值为0.0120,预测精度较高。 相似文献
1000.
《Soils and Foundations》2023,63(3):101312
Liner-cover layers are top layers normally placed when closing landfill sites. The top layers are commonly subjected to the direct influence of moisture, temperature changes, and erosion. This study proposed the use of a dynamic cone penetrometer as a quick tool to assess the shear strength and density of sand-clay cover liners. Poor areas indicating low shear strength and dry density need to be investigated and identified. Changes in moisture content and dry density affect the soil compressibility and shear strength parameters. A lightweight dynamic probe was found to give reliable shear strength measurements when assessing bentonite sand mixture materials. The impact of the moisture content on the profile of penetration was established and a bilinear relationship between the cone penetration and moisture content is shown. Laboratory fall cone tests were conducted to verify the trends of penetration and the influence of dry density. It was found that a linear function can be established within the wet of the optimum zone of the compaction curve. The tests conducted support the effectiveness of using dynamic cone penetrometers for measurements and evaluation of shear strength and dry density for sand clay cover liners. This will pave the way for using a quick tool for the assessment of compaction uniformity and shear strength of sand clay cover liners. 相似文献