全文获取类型
收费全文 | 283148篇 |
免费 | 5580篇 |
国内免费 | 1858篇 |
专业分类
电工技术 | 6397篇 |
技术理论 | 3篇 |
综合类 | 1784篇 |
化学工业 | 41347篇 |
金属工艺 | 11583篇 |
机械仪表 | 10021篇 |
建筑科学 | 7830篇 |
矿业工程 | 2012篇 |
能源动力 | 7156篇 |
轻工业 | 24503篇 |
水利工程 | 3028篇 |
石油天然气 | 5390篇 |
武器工业 | 226篇 |
无线电 | 37158篇 |
一般工业技术 | 52994篇 |
冶金工业 | 47844篇 |
原子能技术 | 5646篇 |
自动化技术 | 25664篇 |
出版年
2022年 | 1911篇 |
2021年 | 3021篇 |
2020年 | 2269篇 |
2019年 | 2688篇 |
2018年 | 4234篇 |
2017年 | 4338篇 |
2016年 | 4471篇 |
2015年 | 3230篇 |
2014年 | 5228篇 |
2013年 | 12732篇 |
2012年 | 8058篇 |
2011年 | 10460篇 |
2010年 | 8402篇 |
2009年 | 9132篇 |
2008年 | 9969篇 |
2007年 | 9822篇 |
2006年 | 8977篇 |
2005年 | 8191篇 |
2004年 | 7606篇 |
2003年 | 7396篇 |
2002年 | 7059篇 |
2001年 | 7046篇 |
2000年 | 6696篇 |
1999年 | 6844篇 |
1998年 | 14709篇 |
1997年 | 10667篇 |
1996年 | 8477篇 |
1995年 | 6724篇 |
1994年 | 6003篇 |
1993年 | 5800篇 |
1992年 | 4718篇 |
1991年 | 4329篇 |
1990年 | 4111篇 |
1989年 | 3845篇 |
1988年 | 3697篇 |
1987年 | 3216篇 |
1986年 | 3098篇 |
1985年 | 3631篇 |
1984年 | 3397篇 |
1983年 | 3041篇 |
1982年 | 2864篇 |
1981年 | 2961篇 |
1980年 | 2767篇 |
1979年 | 2659篇 |
1978年 | 2503篇 |
1977年 | 2950篇 |
1976年 | 3558篇 |
1975年 | 2321篇 |
1974年 | 2314篇 |
1973年 | 2321篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Application of high‐temperature Fenton oxidation for the treatment of sulfonation plant wastewater
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
132.
133.
134.
This study addresses the thermo‐diffusion and the diffusion‐thermo phenomena in a semi‐infinite absorbent channel whose walls are contracting/expanding, with heat source/sink effects. The governing partial differential equations with suitable boundary conditions are transformed to a system of dimensionless ordinary differential equations. An analytic solution of the problem has been found using a technique called homotopy analysis method (HAM). HAM gives consistently valid answers to the problem over an extensive variety of parameters and also provides better accuracy. To validate the analytical results, a comparison has been presented with a numerical solution calculated by using the parallel shooting method. The effects of dimensionless parameters, that is, deformation parameter, Reynolds number, Soret and Dufour numbers, and heat source/sink parameter on the expressions of velocity, temperature, and concentration profiles are analyzed graphically to understand the physics of the deformable channel. It has been noted that the velocity across the channel is higher for the expanding channel, as compared to that for the contracting channel. Also the Soret and Dufour number increases the temperature of the fluid, and decreases the concentration. The temperature profile has an increasing behavior in the case of heat source, and a decreasing behavior in the case of heat sink. 相似文献
135.
Wax deposit properties are a significant concern in pipeline pigging during waxy crude oil transportation. In the present work, the impacts of flow conditions and oil properties on the wax precipitation characteristics of wax deposits are investigated. A flow loop apparatus was developed to conduct wax deposition experiments using four crude oils collected from different field pipes. The differential scanning calorimetry (DSC) technique was employed to observe the wax precipitation characteristics of crude oil and wax deposit. The results show that the wax content and the wax appearance temperature (WAT) of the deposits increase with shear stress and radial temperature gradient, and decrease with radial wax molecule concentration gradient near the pipe wall. The DSC tests on the wax deposits revealed that the deposit wax content is strongly correlated to the oil wax content. Furthermore, an empirical correlation was developed to predict the wax content and the WAT of the wax deposit. Verification of the empirical correlation using the different oils indicated that the average relative error of the wax content prediction and average absolute error of WAT prediction were 13.2% and 3.6°C, respectively. 相似文献
136.
137.
D. A. Kudryashov A. S. Gudovskikh A. M. Mozharov A. D. Bol’shakov I. S. Mukhin Zh. I. Alferov 《Technical Physics Letters》2015,41(12):1120-1123
Design and operation modes of double-junction monolithic lattice-matched solar cells based on the ZnSiP2/Si system of materials have been calculated. The effect of the photoactive region thickness and minority carrier lifetime in ZnSiP2 layers on the efficiency of conversion of the incident solar light energy into electrical power was determined. It is shown that solar cells based on ZnSiP2/Si heterostructures can provide efficiencies of 28.8% at AM1.5D, 100 mW/cm2, and 33.3% at AM1.5D, 200 W/cm2. 相似文献
138.
Jianmou Lu Yanli Huang Shunyan Ren 《International Journal of Control, Automation and Systems》2020,18(5):1250-1263
This paper investigates the general decay synchronization and general decay H∞ synchronization problems of multi-weighted coupled reaction-diffusion 相似文献
139.
The dynamic interaction between the mechanical and electrical drive parameters when damage suddenly appears in the mechanical part of a conveyer belt is investigated. The possibility of using the change in the motor’s electrical parameters as a diagnostic signal is assessed. A model for investigating the dynamic processes in the system consisting of the grid, the induction motor, and the conveyer belt is proposed. The grid and induction motor are described by a model of fourth-order state space, whose output is the torque at the motor shaft. The moments of inertia and pliability of the links between the elements in the mechanical part of the conveyer belt are determined. By gradually identifying the elements with the minimum moment of inertia and distributing their moments of inertia and pliabilities among the adjacent elements, we obtain a three-mass system simulating the mechanical part of the conveyer belt. This dynamic model is solved by means of Matlab Simulink software. The energy characteristics of the drive are determined in dynamic processes following a mechanical accident. 相似文献
140.
Lisichkin S. E. Rubin O. D. Pashchenko F. A. 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2021,55(3):373-379
Power Technology and Engineering - The experimental results on retaining reinforced-concrete walls reinforced with anchor ties and carbon composite materials on the face side of hydraulic... 相似文献