全文获取类型
收费全文 | 88648篇 |
免费 | 7521篇 |
国内免费 | 3962篇 |
专业分类
电工技术 | 9849篇 |
技术理论 | 7篇 |
综合类 | 7881篇 |
化学工业 | 11157篇 |
金属工艺 | 3955篇 |
机械仪表 | 4390篇 |
建筑科学 | 15517篇 |
矿业工程 | 3902篇 |
能源动力 | 3678篇 |
轻工业 | 5232篇 |
水利工程 | 4210篇 |
石油天然气 | 2705篇 |
武器工业 | 963篇 |
无线电 | 5912篇 |
一般工业技术 | 10698篇 |
冶金工业 | 4452篇 |
原子能技术 | 967篇 |
自动化技术 | 4656篇 |
出版年
2024年 | 351篇 |
2023年 | 1023篇 |
2022年 | 2116篇 |
2021年 | 2622篇 |
2020年 | 2944篇 |
2019年 | 2157篇 |
2018年 | 2113篇 |
2017年 | 2708篇 |
2016年 | 2903篇 |
2015年 | 2972篇 |
2014年 | 5384篇 |
2013年 | 5136篇 |
2012年 | 6286篇 |
2011年 | 6541篇 |
2010年 | 5027篇 |
2009年 | 5409篇 |
2008年 | 4835篇 |
2007年 | 6442篇 |
2006年 | 5767篇 |
2005年 | 4953篇 |
2004年 | 4130篇 |
2003年 | 3597篇 |
2002年 | 2931篇 |
2001年 | 2439篇 |
2000年 | 2068篇 |
1999年 | 1565篇 |
1998年 | 1210篇 |
1997年 | 958篇 |
1996年 | 822篇 |
1995年 | 656篇 |
1994年 | 568篇 |
1993年 | 377篇 |
1992年 | 258篇 |
1991年 | 177篇 |
1990年 | 130篇 |
1989年 | 146篇 |
1988年 | 101篇 |
1987年 | 50篇 |
1986年 | 34篇 |
1985年 | 51篇 |
1984年 | 27篇 |
1983年 | 21篇 |
1982年 | 21篇 |
1981年 | 12篇 |
1980年 | 29篇 |
1979年 | 10篇 |
1959年 | 7篇 |
1956年 | 4篇 |
1955年 | 5篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
121.
122.
V. Anjos M.J.V. Bell E.F. da Silva Jr. R.W.A. Franco I.A. Esquef 《Microelectronics Journal》2005,36(11):977-980
In this paper we report the use of photothermal techniques such as Thermal lens (TL) spectrometry, Photoacoustic and heat capacity, ρcp, to determine the thermo-optical parameters, such as thermal conductivity (K), thermal diffusivity (D), specific heat (cp) and the optical path dependence with temperature (ds/dT), of an undoped polycrystalline 3C-SiC. To our knowledge, this is the first time that Thermal lens technique is used for wide band-gap systems. Results obtained for the polycrystalline sample with TL technique indicates that ds/dT is negative at room temperature. Moreover, the obtained values of thermal diffusivity and thermal conductivity are in good agreement with that found in the literature, indicating that the phototermal techniques can be used to obtain the referred parameters in circumstances where other techniques cannot be used, for example, in harsh environments. 相似文献
123.
Two different Ti/Pt–Ir materials (commercial and home made) and Ti/PdO + Co3O4 were investigated for their electrocatalytic properties versus Cl2 evolution reaction. The materials were used in a batch electrochemical reactor to treat biologically recalcitrant di-azo compound. An electrochemically driven oxidation, mediated by a Cl2/Cl− couple, proved efficient for destruction of this complex organic molecule, causing cleavage of the conjugated double bonds and destruction of unsatured bonds. Both Ti/Pt–Ir materials performed well; lower kinetics obtained with the Ti/PdO + Co3O4 anode was caused by adsorption of the model compound, evidenced in preliminary voltammetric measurements. The dye oxidation reaction followed the second order kinetics with partial orders in the model compound and (time varying) chlorine concentrations equal to one. Specific energy consumption of 3.12 kWh m−3 proved the process more economic than the homogeneous phase oxidation. 相似文献
124.
125.
D.H.R. Price J.A. Sharp 《International Journal of Electrical Power & Energy Systems》1985,7(3):131-137
Peak demand forecasts obtained from six different univariate forecasting methods, under a range of conditions, were used to drive a capacity acquisition model of a large electrical supply system; and the resulting physical and financial performance of the model was observed for each set of forecasts. The results obtained are discussed in the context of their implications for the choice of load forecasting method used in capacity acquisition planning by a power supply undertaking. 相似文献
126.
随着电容测量技术的迅速发展,电容传感器在非电量测量和自动检测中得到广泛应用,但它在使用过程中也存在一些问题,针对在使用电容传感器过程中存在的几个问题,从电容传感器的原理和工作过程两个方面进行了讨论,并提出行之有效的处理方法。 相似文献
127.
128.
129.
The saturation capacity of n-alkanes in CHA, AFX and ERI zeolites, that consist of cages separated by windows, decreases with increasing carbon number. The major aim of the present communication is to demonstrate the possibility of separating n-alkane mixtures relying on differences in saturation capacities. To investigate this possibility, Configurational-Bias Monte Carlo simulations for adsorption of C3–nC6, nC4–nC6, and nC5–nC6 mixtures in CHA, AFX and ERI were carried out for equimolar bulk fluid phase. These mixture simulations show that for operation at fluid phase fugacities below about 1 MPa, the adsorbed phase in equilibrium with the bulk vapor phase is predominantly the alkane with the longer chain length, i.e. nC6. However, for operation at pressures in excess of 1 MPa, the adsorbed phase in equilibrium with the bulk liquid phase is richer in the component with the smaller chain length. In some cases, the nC6 is practically excluded from the zeolite. 相似文献
130.
The present study is an investigation on the behaviors of concrete-filled thin-walled steel tubular members subjected to combined loading, such as compression and torsion, bending and torsion, compression, bending and torsion. ABAQUS software is used in this paper for the finite element analysis (FEA). A comparison of results calculated using this modeling shows generally good agreement with test results. The FEA modeling is then used to investigate the influence of important parameters that determine the ultimate strength of the composite members under combined loading, such as compression and torsion, bending and torsion, compression, bending and torsion. The parametric studies provide information for the development of formulae for calculating the ultimate strength of the composite members subjected to combined loading. 相似文献