全文获取类型
收费全文 | 76篇 |
免费 | 7篇 |
国内免费 | 7篇 |
专业分类
化学 | 33篇 |
晶体学 | 1篇 |
力学 | 20篇 |
综合类 | 2篇 |
数学 | 2篇 |
物理学 | 32篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 8篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有90条查询结果,搜索用时 31 毫秒
21.
A room temperature vulcanization silicone rubber was widely used as the mold making material due to its high elasticity, good heat-resistance and low surface energy. To enhance the efficiency of making the silicone rubber mold, accurately measuring the solidification time is an important issue. This study demonstrated a non-invasive measurement system to measure the solidification time of silicone rubber. The solidification time can be determined rapidly from the thickness of silicone rubber according to the predicted equation. The maximum relative error of the predicted equation is about 8.26%. The temperature rise of the silicone during the solidification process is an important phenomenon to determine the solidification behavior of silicone rubber. The solidification mechanism of silicone rubber mold is demonstrated. 相似文献
22.
建立了黏弹性流体在充模过程中带有相变的气一液两相模型,该模型分别由气、液两相的质量守恒方程、动量守恒方程、能量守恒方程描述,并通过引入Heaviside函数将气一液两相的方程组统一为一个方程组;建立了一个对型腔内熔体和气体都适用的修正的焓方法来描述充模过程中的相变,采用基于同位网格的有限体积方法对模型进行求解,水平集方法捕捉充模过程中的界面演化,模拟出了黏弹性流体在充模过程中的凝固现象,得出了充模过程中型腔内的温度、压力、第一法向应力差等随时间的变化;并讨论了型腔壁面温度、熔体温度、注射速度对充模过程中凝固现象的影响,研究结果表明:型腔壁面温度越高,凝固层越薄;熔体温度越高,凝固层越薄;注射速度越高,凝固层越薄,故提高型腔壁面温度、熔体温度、注射速度可以减少或消除型腔壁面附近的凝固层。 相似文献
23.
在纳米印章技术中,为克服电子束刻蚀制备50nm以下线条的技术难点,利用等离子增强化学 气相沉积技术制备了a-Si/SiNx多层膜,再利用选择性湿法腐蚀或干法腐蚀在横 截面上制备出浮雕型一维纳米级模板. 多层膜子层之间界面清晰陡峭,可以在纳米量级对子 层厚度进行控制,得到了侧壁在纳米尺度上平滑的模板. 通过控制多层膜子层的生长时间, 制备出线条宽度和槽状宽度均为20nm的等间距模板,品质优于电子束刻蚀技术制备的模板.
关键词:
纳米印章模板
多层膜生长技术 相似文献
24.
流动诱导残余应力是塑料制品产生应力开裂以及翘曲变形等现象的重要原因,对成型过程中流动诱导残余应力研究具有重要意义.推导了基于黏弹性eXtended Pom-Pom本构关系的能量方程,进而建立了描述黏弹性流体非等温充模流动的气-液两相模型.用同位网格有限体积法进行了求解,得到了凝固层和剪切速率分布,给出了充填结束时影响制件力学性能的流动诱导残余应力.结果表明,型腔中凝固层的厚度与注射速率有关,注射速率越大,充模时间越短,凝固层越薄.在制品表层紧邻模壁的地方,剪切速率和残余应力几乎为零;在制品次表层的位置,制件内剪切速率和流动残余应力也较高;而在远离模壁的地方,剪切速率和流动残余应力也较小. 相似文献
25.
Shaofeng Xie Frantisek Svec Jean M. J. Frchet 《Journal of polymer science. Part A, Polymer chemistry》1997,35(6):1013-1021
Molded macroporous monoliths with pores sizes up to 1000 nm have been prepared by copolymerization of the hydrophilic monomers, acrylamide, and N,N′-methylenebisacrylamide, in the presence of a porogenic diluent. A combination of dimethylsulfoxide and 2-heptanol was selected from a broad spectrum of solvents and water soluble polymers to achieve the optimum composition of the porogenic mixture. In addition to the composition of the porogen the porous properties of the monolithic rods can also be optimized through changes in the percentage of both N,N′-methylene-bisacrylamide (crosslinking monomer) and azobisisobutyronitrile (free radical initiator) used for the polymerization. The hydrophilic monoliths may be used in the separation of biological polymers, solid-phase extraction, or for immobilization of proteins. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 1013–1021, 1997 相似文献
26.
27.
A novel, fully-analytical design sensitivity formulation for transient, turbulent, free surface flows is derived and implemented in the context of finite element analysis. The time-averaged, turbulent form of the Navier–Stokes equations are solved using a mixing length model, in conjunction with the volume of fluid (VOF) method to model the free surface movement. The design derivatives of these governing equations are computed and solved to find the analytical sensitivities of the fluid position, velocity and pressure fields with respect to shape design variables. The computational efficiency produced by evaluating the sensitivities analytically is demonstrated. The design of the runner and gating system of a simple block casting is presented as an example application for using sensitivity information in design. The analytical sensitivity routine is coupled to a numerical optimizer to yield an automated method for optimal design of the casting rigging system. The results produce runner shapes which eliminate mold-gas aspiration. © 1998 John Wiley & Sons, Ltd. 相似文献
28.
29.
A. N. Kozloborodov G. R. Shrager 《Journal of Applied Mechanics and Technical Physics》2008,49(1):64-70
Flow regimes of the polymer mass filling cylindrical variable-section molds are studied by means of the numerical solution
of the problem of a nonlinear viscoplastic fluid flow with a free surface in cylindrical channels of geometrically complicated
shapes. A mathematical formulation of the problem is given, and factors affecting the molding process are analyzed. Numerical
experiments performed in a wide range of problem parameters make it possible not only to elucidate the specific features of
the hydrodynamic behavior of the free surface of the moving polymer mass, but also to establish the existence of two flow
regimes depending on the ratio of the generalized Reynolds number to the Froude number.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 1, pp. 81–88, January–February, 2008. 相似文献
30.
A small single bubble was generated with a single-hole nozzle facing upward in a water bath contained in a rotating cylindrical
vessel. The bubble size falls in the surface tension force dominant regime. The vertical, radial, and tangential migration
velocities of the bubble were measured with two CCD cameras and a high-speed video camera. The tangential velocity component
of water flow was measured with particle image velocimetry. A helical motion of the bubble was observed under every experimental
condition. The direction of the helical motion was the same as that of the tangential velocity component. This helical motion
is associated with the large initial shape deformation of the bubble near the nozzle exit and the subsequent regular shedding
of vortices behind it. The period and amplitude of the helical motion were obtained by analyzing the trajectory of the bubble.
These quantities were non-dimensionalized by the volume equivalent bubble diameter and the terminal bubble velocity in the
vertical direction and correlated as functions of the Eotvos number. Empirical equations were proposed for the period and
amplitude.
Originally published in the Journal of JSEM, Vol. 4, No. 2, pp. 38–45 (2004). 相似文献