全文获取类型
收费全文 | 6719篇 |
免费 | 675篇 |
国内免费 | 291篇 |
学科分类
工业技术 | 7685篇 |
出版年
2024年 | 24篇 |
2023年 | 84篇 |
2022年 | 151篇 |
2021年 | 185篇 |
2020年 | 179篇 |
2019年 | 160篇 |
2018年 | 168篇 |
2017年 | 179篇 |
2016年 | 219篇 |
2015年 | 218篇 |
2014年 | 407篇 |
2013年 | 378篇 |
2012年 | 408篇 |
2011年 | 462篇 |
2010年 | 389篇 |
2009年 | 380篇 |
2008年 | 372篇 |
2007年 | 419篇 |
2006年 | 385篇 |
2005年 | 318篇 |
2004年 | 286篇 |
2003年 | 254篇 |
2002年 | 243篇 |
2001年 | 229篇 |
2000年 | 197篇 |
1999年 | 152篇 |
1998年 | 140篇 |
1997年 | 137篇 |
1996年 | 77篇 |
1995年 | 80篇 |
1994年 | 79篇 |
1993年 | 59篇 |
1992年 | 64篇 |
1991年 | 36篇 |
1990年 | 29篇 |
1989年 | 35篇 |
1988年 | 28篇 |
1987年 | 17篇 |
1986年 | 16篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1951年 | 7篇 |
排序方式: 共有7685条查询结果,搜索用时 0 毫秒
1.
The miscibility and phase behavior of ternary blends containing dimethylpolycarbonate (DMPC), tetramethylpolycarbonate (TMPC) and poly[styrene‐co‐(methyl methacrylate)] copolymer (SMMA) have been explored. Ternary blends containing polystyrene (PS) instead of SMMA were also examined. Blends of DMPC with SMMA copolymers (or PS) did not form miscible blends regardless of methyl methacrylate (MMA) content in copolymers. However, DMPC blends with SMMA (or PS) blends become miscible by adding TMPC. The miscible region of ternary blends is compared with the previously determined miscibility region of binary blends having the same chemical components and compositions. The region where the ternary blends are miscible is much narrower than that of binary blends. Based on lattice fluid theory, the observed phase behavior of ternary blends was analyzed. Even though the term representing the Gibbs free energy change of mixing for certain ternary blends had a negative value, blends were immiscible. It was revealed that a negative value of the Gibbs free energy change of mixing was not a sufficient condition for miscible ternary blends because of the asymmetry in the binary interactions involved in ternary blends. Copyright © 2004 Society of Chemical Industry 相似文献
2.
Arash Sarhangi Fard Navid M. Famili Patrick D. Anderson 《Computers & Chemical Engineering》2008,32(7):1471-1481
The main objective of the present work is to modify the traditional mapping method for the simulation of distributive mixing of multiphase flows in geometries involving moving parts such as, internal mixers or twin-screw extruders without a limitation on their geometrical periodicity. The periodicity condition, limits the results of traditional mapping method to tracking mapping mesh between specific discrete time intervals or distances for that geometry is repeated, hence, result is only for fixed orientation of rotors. Imaginary domain method is introduced to track mapping mesh from one state to the next free of geometrical periodicity limitations. In this work the method is introduced and its applicability and accuracy is discussed in details. A two-dimensional (2D) simulation of mixing of two Newtonian fluids with different viscosities in an intermeshing internal mixer is used as a test case study. In this example the key issues of ability to predict mixing state in details for all orientations of rotors is presented. To reduce diffusion errors of mapping method in the boundaries of the rotors, mapping mesh refinement technique that relies upon one single reference mesh is also presented. 相似文献
3.
Fernando J. Muzzio Marcos Llusa Christopher L. Goodridge Nhat-Hang Duong Elizabeth Shen 《Powder Technology》2008,186(3):247-254
This paper investigates the effects of processing and equipment parameters of a ribbon blender (i.e. loading method of lubricant, fill level, blade speed and blade design) on magnesium stearate homogeneity. A core sampling technique is used to obtain at least one hundred samples per sampling event, which are extracted throughout the blender and yield a thorough characterization of the entire bed. The results presented here can be used as a guideline to develop appropriate blending processes and characterization protocols for ribbon blenders. 相似文献
4.
边坡支护中多种技术措施的综合应用 总被引:1,自引:0,他引:1
通过工程实例,介绍了锚杆喷射混凝土支护技术与高压喷射混凝土搅拌桩支护技术在工程中的综合利用,同时也验证了该技术的可行性及经济性。 相似文献
5.
6.
Huai Wen-xin Wuhan University of Hydraulic & Electric Engineering Wuhan Hubei P.R.China Prof.Li Wei 《水动力学研究与进展(B辑)》1993,(3)
Turbulence represents an essential aspect in atmospheric and oceanic circulations.In particu-lar,it is a preponderant factor in the dispersion of pollutants of artificial or natural origin.Thevertical turbulent jets,plumes and buoyant jets discharging into static environment is one of themost important and basic flow patterns related with the environment pollution.These flows havenumerous important applications,for example,thrust augmentors,waste disposal plumes fromstacks and combustion systems,and significant problems of turbulent diffusion. 相似文献
7.
磨料高压水除鳞系统设计研究 总被引:1,自引:0,他引:1
磨料高压水除鳞系统取代酸洗线,原机械部分和磨料高压水部分都作了较大改进,才能保证除鳞彻底。 相似文献
8.
磷酸酯淀粉在纯棉细特高密织物浆纱中的应用 总被引:2,自引:0,他引:2
就磷酸酯淀粉在纯棉细号高密织物中的上浆情况进行了试验,提出了具体浆纱工艺和减少织造断头率,提高织物效率及布面质量对策,实验表明,磷酸酯淀粉完全适应于纯绵细特高密织物的上浆要求。 相似文献
9.
10.
HerlinaAdrian Wing-Keung Law 《International Journal of Heat and Mass Transfer》2002,45(24):4899-4905
The results of a laboratory investigation on the turbulence characteristics of a circular three-dimensional turbulent wall jet are presented. Measurements were taken up to 50 nozzle diameters using combined particle image velocimetry and planar laser induced fluorescence. The results showed that the induced turbulence was still evolving in the present range and had not achieved similarity. While the turbulent intensity for both velocity and concentration increased downstream, the turbulent mass transport showed a decline over distance for both the streamwise and spanwise directions, implying weakening dispersion from the jet core. 相似文献