全文获取类型
收费全文 | 206篇 |
免费 | 59篇 |
国内免费 | 23篇 |
专业分类
化学 | 48篇 |
晶体学 | 30篇 |
力学 | 20篇 |
数学 | 13篇 |
物理学 | 177篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 5篇 |
2014年 | 18篇 |
2013年 | 13篇 |
2012年 | 16篇 |
2011年 | 23篇 |
2010年 | 15篇 |
2009年 | 16篇 |
2008年 | 15篇 |
2007年 | 15篇 |
2006年 | 19篇 |
2005年 | 10篇 |
2004年 | 17篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1992年 | 4篇 |
排序方式: 共有288条查询结果,搜索用时 15 毫秒
71.
For big software developing companies, it is important to know the amount of problems of a new software product that are expected to be reported in a period after the date of release, on a weekly basis. For each of a number of past releases, weekly data are present on the number of such reports. Based on the type of data that is present, we construct a stochastic model for the weekly number of problems to be reported. The (non‐parametric) maximum likelihood estimator for the crucial model parameter, the intensity of an inhomogeneous Poisson process, is defined. Moreover, the expectation maximization algorithm is described, which can be used to compute this estimate. The method is illustrated using simulated data. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
72.
计算机控制光学表面抛光的磨头运动方式和参数的优化研究 总被引:5,自引:1,他引:4
对影响计算机数控抛光表面误差收敛速度的主要因素———磨头工作函数进行了详细的讨论。提出了以趋近因子作为评价磨头参数优化的参量。对目前流行的行星式磨头和平转动磨头分别作优化,给出了最佳参数组合,为提高计算机控制抛光的效率提供了理论依据。 相似文献
73.
74.
75.
76.
77.
We report an easy method to tune up screen‐printed carbon electrodes (SPCEs) for application in fabricating disposable electrochemical sensors. Simply by ultrasonic polishing a bare SPCE in a γ‐Al2O3 slurry, the surface roughness was drastically smoothed coupled with a large increase in hydrophilicity. The as‐generated micromorphology on the surface of the SPCE was found to be ideal for the immobilization of catechol to minimize the overpotential in the sensitive detection of nicotinamide adenine dinucleotide (NADH) and hydrazine. Physical characterization by both XPS and AFM studies specify that the adsorption behavior is related to the carbon surface functionalities and the trapping of γ‐Al2O3 on the polished‐SPCE. 相似文献
78.
本文利用改进的垂直无籽晶气相升华法生长出尺寸达Φ30×40 mm的优质硒化镉(CdSe)单晶体。解理晶体,通过X射线衍射仪测试精确的获得(001)晶面。然后定向切割、研磨、抛光,获得了尺寸为20×20×3mm~3的CdSe中红外波片初胚。以弱碱性溶液与刚玉粉的混合液作为抛光液,利用化学机械抛光法对CdSe中红外波片进行表面抛光处理。结果显示,抛光处理有效的减少了波片表面的损伤层、划痕及结构缺陷,晶片表面的粗糙度降低,在2~20μm波段透过率较高(达到70%),满足中红外波片的应用需求。 相似文献
79.
YongweiZhu ZhijingFeng BaichunWang XianyangXu 《中国颗粒学报》2004,2(4):153-156
Mechanochemical Modification (MCM) of nanodiamond surface with DN-10 was studied in relation to the performance of nanodiamond in polishing quartz wafers. Results show that the modified nanodiamond is more stable in the pH range 8-11. A super smooth surface with an average roughness of 0.214 nm was achieved using a nanodiamond-based slurry regulated by N-(2-hydroxyethyl)ethylenediamine. It is suggested that the principal ultra-fine polishing mechanism of auartz wafer involves atom-level removal under the synergism of chemical and mechanical actions. 相似文献
80.
J.J. Vlassak 《Journal of the mechanics and physics of solids》2004,52(4):847-873
A new contact-mechanics-based model for chemical-mechanical polishing is presented. According to this model, the local polish rate is controlled by the pressure distribution between features on the wafer and the polishing pad. The model uses an analysis based on the work by Greenwood to evaluate this pressure distribution taking into account pad compliance and roughness. Using the model, the effects of pattern density, applied down-force, selectivity, pad properties, etc. on the evolution of the wafer surface can be readily evaluated. The interaction between individual pad asperities and the wafer pattern is investigated in detail. It is shown that the pressure distribution between an asperity and the wafer surface is discontinuous at edges of features that have different nominal polish rates and that this pressure discontinuity dominates the polish rate and dishing of narrow features.The model is implemented as an algorithm that calculates the evolution of the profile of a set of features on the wafer during the polishing process. The model can be applied to chemical-mechanical polishing used for oxide planarization, metal damascene or shallow trench isolation. 相似文献