全文获取类型
收费全文 | 616篇 |
免费 | 25篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 23篇 |
综合类 | 3篇 |
化学工业 | 139篇 |
金属工艺 | 14篇 |
机械仪表 | 16篇 |
建筑科学 | 9篇 |
矿业工程 | 4篇 |
能源动力 | 48篇 |
轻工业 | 18篇 |
水利工程 | 4篇 |
无线电 | 76篇 |
一般工业技术 | 158篇 |
冶金工业 | 67篇 |
原子能技术 | 7篇 |
自动化技术 | 61篇 |
出版年
2024年 | 6篇 |
2023年 | 7篇 |
2022年 | 18篇 |
2021年 | 43篇 |
2020年 | 34篇 |
2019年 | 35篇 |
2018年 | 28篇 |
2017年 | 31篇 |
2016年 | 30篇 |
2015年 | 27篇 |
2014年 | 21篇 |
2013年 | 44篇 |
2012年 | 27篇 |
2011年 | 41篇 |
2010年 | 32篇 |
2009年 | 33篇 |
2008年 | 27篇 |
2007年 | 16篇 |
2006年 | 19篇 |
2005年 | 10篇 |
2004年 | 16篇 |
2003年 | 10篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有647条查询结果,搜索用时 16 毫秒
71.
An 82 year old man developed antibodies against coagulation factor VIII:C without any apparent cause. Bleeding from the soft tissue cavity could not be controlled by factor VIII:C concentrates, immunosuppression with steroids and intravenous immunoglobulin therapy in the standard dosages. However, a single injection of Epsilon Aminocaproic Acid (EACA) instilled into the cavity under aseptic precautions achieved lasting hemostasis with resultant wound healing. 相似文献
72.
The emf of cells Ag AgCl, HCl(m), QH2, Q Pt, Hg Hg2Cl2, HCl(m), QH2, Q Pt and Pt H2, HCl(m), QH2, Q Pt have been measured at 25°C using formamide as solvent. The standard potential of the quinhydrone electrode obtained from the above cells is 0·7151 ± 0·0009, 0·7137 ± 0·0005 and 0·7140 ± 0·0002 V respectively. The calculated mean molal activity coefficients of HCl agree fairly well with earlier reported results. 相似文献
73.
Performance of a dual maximal ratio combining receiver has been analyzed in correlated Hoyt fading channels. Analytical expressions for the probability density function of the receiver output signal-to-noise ratio (SNR), average SNR, outage probability and average bit error rate performance for binary, coherent and non-coherent modulations have been presented. Numerical results show that for coherent phase shit-keying and differential phase shift-keying modulations, to achieve an ABER of 10?7, the required excess SNR is relatively small for correlation coefficient (?) less than 0.5 than it is for ? ≫ 0.5. 相似文献
74.
Olusola O. James Sudip Maity M. Adediran Mesubi Lamidi A. Usman Kolawole O. Ajanaku Tolu O. Siyanbola Satanand Sahu Rashmi Chaubey 《国际能源研究杂志》2012,36(6):691-702
Dependence on fossil fuels for global energy supply has continued to generate concerns about climate change and sustainable development. It has motivated the search for carbon‐neutral alternative resources for the production of transportation fuels to replace crude oil. Although biodiesels have recently emerged as a close substitute to petrol diesel, their use in compression ignition engines designed to run on petro‐diesel fuels are linked to adverse effects on the engines' performance and life span. This informed efforts at upgrading biodiesel or direct conversion of triglycerides to hydrocarbon mixtures that are identical or similar to that of petro‐diesel through hydrodeoxygenation. Moreover, it seems that commercial methods for the conversion of triglycerides to diesel fuels depends on inputs (methanol and hydrogen) derived from fossil fuels. However, it will be desirable to do so without inputs from fossil fuels. Hence, reaction paths for direct conversion of triglycerides to on‐specification hydrocarbons fuels without hydrogen gas input are discussed and suggested strategies are in cognisance of green chemistry principles. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
75.
Berhampur is one of the oldest and biggest towns of Orissa State where 93% of people earn their living from non-primary economic activities. The fuel consumption structure reveals an element of rural bias since the domestic sector derives 49% of its energy used for cooking and heating from biomass sources. Firewood is the only fuel used by all income groups and almost all occupations. Other traditional fuels such as dungcake, agricultural waste and leaf litter are used in the town with different degrees of dominance in various occupation groups and income classes. The inequality of income distribution is reflected in the fuel consumption structure of the rich and poor with greater dependence on non-biomass in the high income group and biomass in the low income group. Family size is an important determinant of biomass fuel use. For the urban poor, there is a relationship between income and fuel consumption. There exists scope for enlarging the biomass base by utilising the available bio-wastes and developing a green belt around the town. This requires some rural features in the urban area using new technologies. 相似文献
76.
A two-step process for production of hydrogen from vacuum residue has been developed. In the first step, which has already been communicated [18], the residue is reacted with ozone to get oxidized and cracked products. Next, the catalytic oxidative steam reforming of the product obtained after ozonation over a Pt catalyst supported on La2O3-CeO2-γ-Al2O3 was carried out. Effects of the operating conditions: the temperature, the steam to carbon ratio and the oxygen to carbon ratio on oxidative steam reforming were investigated. The oxidative steam reforming was efficient at the molar ratio of O2/C = 0.5, S/C = 4 at 1173 K. Pt catalyst deactivated with time due to coke formation. The catalyst could be regeneration by blowing oxygen through the catalytic bed. Catalysts were characterized by XRD, N2 adsorption–desorption and thermo gravimetrically to understand the microstructures. 相似文献
77.
The present electricity grid installation cost as well as the tariff is quite high in India, particularly remote rural areas, to electrify houses. These problems can be easily solved by installing standalone systems that operate on one of the clean energy sources such as solar energy. An experimental analysis of generating electricity from a thermoelectric generator (TEG) powered by a solar parabolic dish concentrator device with aperture area and focal length of 12.6 m2 and 2.42 m, respectively, is presented in this article. A TEG is made up of a thermoelectric module connected to a flat receiver by an absorber layer. The studies were carried out in Indian climatic conditions at the National Institute of Technology, Puducherry. Over a spectrum of beam radiation, the system's maximum energy conversion efficiency, as well as efficient electrical output, are evaluated and presented. The proposed system's average effective electrical efficiency is 0.424%, corresponding to the TEG's average energy conversion efficiency of 2.76%. 相似文献
78.
79.
P. Koteswara Rao Akhilesh K. Sahu R.P. Chhabra 《International Journal of Heat and Mass Transfer》2011,54(1-3):390-403
Numerical solutions are sought, using FLUENT, to the mass, momentum and thermal energy equations for the 2-D flow of power-law fluids over a cylinder of square cross-section. The major thrust of this work is to delineate the values of the Reynolds number denoting the onset of flow separation and the limits of the steady flow regime for both shear-thinning and shear-thickening type fluids. Extensive results are reported on streamline and vorticity contours over wide ranges of power-law index (0.2–1.4) corroborating the occurrence of these two transitions. Having established the limits of the steady flow regime, drag and Nusselt number results are obtained in this regime as functions of the Reynolds number (0.1–40), of Prandtl number (0.7–100) for highly shear-thinning fluids (power-law index < 0.5) thereby extending the range of currently available results to that encountered in practical applications. The Nusselt number shows positive dependence on both the Reynolds and Prandtl numbers. Also, shear-thinning characteristics can augment the rate of heat transfer by up to 100% under appropriate conditions. 相似文献
80.
G. Selvarani S.K. Prashant A.K. Sahu P. Sridhar S. Pitchumani A.K. Shukla 《Journal of power sources》2008
A direct borohydride-hydrogen peroxide fuel cell employing carbon-supported Prussian Blue (PB) as mediated electron-transfer cathode catalyst is reported. While operating at 30 °C, the direct borohydride-hydrogen peroxide fuel cell employing carbon-supported PB cathode catalyst shows superior performance with the maximum output power density of 68 mW cm−2 at an operating voltage of 1.1 V compared to direct borohydride-hydrogen peroxide fuel cell employing the conventional gold-based cathode with the maximum output power density of 47 mW cm−2 at an operating voltage of 0.7 V. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Analysis (EDAX) suggest that anchoring of Cetyl-Trimethyl Ammonium Bromide (CTAB) as a surfactant moiety on carbon-supported PB affects the catalyst morphology. Polarization studies on direct borohydride-hydrogen peroxide fuel cell with carbon-supported CTAB-anchored PB cathode exhibit better performance with the maximum output power density of 50 mW cm−2 at an operating voltage of 1 V than the direct borohydride-hydrogen peroxide fuel cell with carbon-supported Prussian Blue without CTAB with the maximum output power density of 29 mW cm−2 at an operating voltage of 1 V. 相似文献