全文获取类型
收费全文 | 2770篇 |
免费 | 54篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 42篇 |
综合类 | 3篇 |
化学工业 | 556篇 |
金属工艺 | 162篇 |
机械仪表 | 70篇 |
建筑科学 | 149篇 |
矿业工程 | 10篇 |
能源动力 | 98篇 |
轻工业 | 225篇 |
水利工程 | 26篇 |
石油天然气 | 62篇 |
武器工业 | 1篇 |
无线电 | 207篇 |
一般工业技术 | 690篇 |
冶金工业 | 205篇 |
原子能技术 | 80篇 |
自动化技术 | 250篇 |
出版年
2021年 | 30篇 |
2020年 | 21篇 |
2019年 | 23篇 |
2018年 | 66篇 |
2017年 | 53篇 |
2016年 | 55篇 |
2015年 | 42篇 |
2014年 | 45篇 |
2013年 | 105篇 |
2012年 | 102篇 |
2011年 | 158篇 |
2010年 | 130篇 |
2009年 | 131篇 |
2008年 | 94篇 |
2007年 | 111篇 |
2006年 | 113篇 |
2005年 | 63篇 |
2004年 | 64篇 |
2003年 | 84篇 |
2002年 | 79篇 |
2001年 | 90篇 |
2000年 | 61篇 |
1999年 | 51篇 |
1998年 | 94篇 |
1997年 | 88篇 |
1996年 | 59篇 |
1995年 | 48篇 |
1994年 | 50篇 |
1993年 | 54篇 |
1992年 | 38篇 |
1991年 | 41篇 |
1990年 | 30篇 |
1989年 | 35篇 |
1988年 | 34篇 |
1987年 | 38篇 |
1986年 | 44篇 |
1985年 | 31篇 |
1984年 | 35篇 |
1983年 | 14篇 |
1982年 | 19篇 |
1981年 | 26篇 |
1980年 | 15篇 |
1979年 | 21篇 |
1978年 | 14篇 |
1977年 | 21篇 |
1976年 | 32篇 |
1975年 | 14篇 |
1974年 | 18篇 |
1973年 | 16篇 |
1971年 | 14篇 |
排序方式: 共有2836条查询结果,搜索用时 234 毫秒
941.
Neural Computing and Applications - Knowledge of groundwater level is very important in studies dealing with utilization and management of groundwater supply. Earlier studies have reported that ELM... 相似文献
942.
S. Sahoo B. B. Jha T.S. Mahata J. Sharma T. S. R. Ch. Murthy A. Mandal 《Materials Science & Technology》2018,34(16):1965-1975
Impression creep behaviour of the powder metallurgy processed steel matrix composites was investigated under constant stress at different temperatures in the range of 873–973?K. By using the power-law relationship, the estimated activation energy for unreinforced steel was found to be 149?kJ?mol?1 and steel reinforced with 2 and 4?vol.-% TiB2 was found to be 298 and 338?kJ?mol?1, respectively indicating better creep resistance of the reinforced steel matrix composites. Dislocation creep is the dominant creep mechanism based on the calculated values of stress exponent and activation energy. Hence, this method can be used to assess the potential of steel matrix composites for use as structural materials for high-temperature application. 相似文献
943.
Jacek G. Chęcmanowski Irena Szczygieł Anna Mazur Bogdan Szczygieł 《Ceramics International》2019,45(2):2811-2819
Five layer SiO2 coatings containing SiO2 or Al2O3 nanopowders were deposited on FeCrAl alloy support by sol-gel method. Studies of protective properties of the coatings were carried out during high temperature cyclic oxidation. Changes in surface topography, structure and chemical composition of the surface layer of FeCrAl alloy were investigated. It has been shown that the type of nanofillers present in the SiO2 coating (about 2.5?wt%) affects morphology of Al2O3 growing scale and determines the heat resistance of FeCrAl alloy. The lowest relative mass change (approx. 1.3%) after 10 oxidation cycles in air at 900?°C (one cycle = 12?h) was measured for the samples with coatings containing hydrophilic nanosilica (Aerosil 380) as filler. The protective efficiency of the coatings in the process of high-temperature oxidation is from 66% to 85%. The thickness of the formed scale and the value of the parabolic rate constant depend on the type of nanopowder in the coating. 相似文献
944.
945.
S. Tirano L. PerniolaJ. Buckley J. CluzelV. Jousseaume Ch. MullerD. Deleruyelle B. De SalvoG. Reimbold 《Microelectronic Engineering》2011,88(7):1129-1132
In this paper, a peculiar attention is turned towards the understanding of the current overshoot occurring during the forming operation in resistive switching memory devices. This phenomenon is attributed to the discharge of a parasitic capacitance in parallel to the resistive device in simple 1R (one resistor, no transistor/diode selector) architectures. The impact of such an overshoot is analyzed on both NiO and HfO2-based memory elements by performing measurements with different setups (quasi-static and pulse measurements). We show that the parasitic event is more severe as the forming voltage in the memory device increases. Moreover, it is shown that the post-forming resistance cannot be simply adjusted by a current compliance available on semiconductor parameter analyzers, since this internal limiter is ineffective in the microsecond range for compliance levels lower than the current spike. The current overshoot playing a detrimental role on the electrical performances of resistive devices, it must be carefully monitored when assessing the electrical performances in simple 1R architectures. 相似文献
946.
V. Yu. Rud’ Yu. V. Rud’ V. Ch. Shpunt E. I. Terukov 《Optical Memory & Neural Networks》2016,25(1):40-44
A photovoltaic effect has been discovered at a contact between a semiconductor and biological origin materials. Photoelectrical properties of the new type structures have been investigated. Structures consisting of a semiconductor and materials of biological origin can be used as photovoltaic converters for natural and linearly polarized light. It needs for information transmission over distances, as well as for analysis of the polarization state of the laser radiation in communication systems. 相似文献
947.
Ya. E. Shakhova Zh. Ch. Yanushkevich A. N. Belyakov 《Russian Metallurgy (Metally)》2012,2012(9):772-778
The effect of section rolling of austenitic corrosion-resistant 10Kh18N8D3BR steel at room temperature on its structure and mechanical properties is studied. During section rolling, the steel acquires a lamellar-type structure consisting of α′-martensite lamellas and retained austenite, and the fraction of α′ martensite increases to 70% at a true strain ? ≈ 4. In the initial state, the yield strength of the steel is 285MPa and the relative elongation is 60%. Cold plastic deformation to ? ≈ 0.4 increases the yield strength to 1010 MPa. Further deformation is accompanied by higher hardening of the steel: the yield strength increases to 2050 MPa at ? ≈ 4, and the relative elongation decreases to 2%. 相似文献
948.
The efficient training of young environmental scientists has proven to be a challenging goal over the last years, while several dynamic initiatives have been developed aiming to provide complete and consistent education. A successful example is the e-learning course for participants mainly coming from emerging economy countries ‘Development of mitigation/adaptation policy portfolios’ organised in the frame of the project Promitheas4: Knowledge transfer and research needs for preparing mitigation/adaptation policy portfolios, aiming to provide knowledge transfer, enhance new skills and competencies, using modern didactic approaches and learning technologies. The present paper addresses the experience and the results of these actions, which seem promising and encouraging and were broadly welcomed by the participants. 相似文献
949.
M. Muehlebach T. Heimsch Ch. Glocker 《International journal for numerical methods in engineering》2017,109(11):1549-1581
This article presents a family of variational integrators from a continuous time point of view. A general procedure for deriving symplectic integration schemes preserving an energy‐like quantity is shown, which is based on the principle of virtual work. The framework is extended to incorporate holonomic constraints without using additional regularization. In addition, it is related to well‐known partitioned Runge–Kutta methods and to other variational integration schemes. As an example, a concrete integration scheme is derived for the planar pendulum using both polar and Cartesian coordinates. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
950.
B. Ch. Balabekov A. M. Brener O. S. Balabekov 《Theoretical Foundations of Chemical Engineering》2016,50(3):273-285
Approximate models are developed for calculating heat and mass transfer processes in gas-drop flows that pass over a regular packed bed with cylindrical elements. A number of different flow regimes are considered: flat laminar flow, the formation of the stationary vortex behind packing element and formation of nonstationary vortex wake. Criterial equations for calculating corresponding mass transfer parameters are obtained. 相似文献