全文获取类型
收费全文 | 50961篇 |
免费 | 7993篇 |
国内免费 | 6423篇 |
专业分类
化学 | 37296篇 |
晶体学 | 641篇 |
力学 | 2954篇 |
综合类 | 427篇 |
数学 | 5853篇 |
物理学 | 18206篇 |
出版年
2024年 | 115篇 |
2023年 | 1010篇 |
2022年 | 1554篇 |
2021年 | 1854篇 |
2020年 | 2064篇 |
2019年 | 2007篇 |
2018年 | 1719篇 |
2017年 | 1615篇 |
2016年 | 2262篇 |
2015年 | 2274篇 |
2014年 | 2817篇 |
2013年 | 3602篇 |
2012年 | 4405篇 |
2011年 | 4496篇 |
2010年 | 3189篇 |
2009年 | 2973篇 |
2008年 | 3230篇 |
2007年 | 2778篇 |
2006年 | 2664篇 |
2005年 | 2316篇 |
2004年 | 1953篇 |
2003年 | 1562篇 |
2002年 | 1523篇 |
2001年 | 1321篇 |
2000年 | 1086篇 |
1999年 | 1145篇 |
1998年 | 912篇 |
1997年 | 769篇 |
1996年 | 913篇 |
1995年 | 746篇 |
1994年 | 681篇 |
1993年 | 576篇 |
1992年 | 532篇 |
1991年 | 460篇 |
1990年 | 391篇 |
1989年 | 280篇 |
1988年 | 249篇 |
1987年 | 227篇 |
1986年 | 169篇 |
1985年 | 186篇 |
1984年 | 145篇 |
1983年 | 131篇 |
1982年 | 86篇 |
1981年 | 65篇 |
1980年 | 54篇 |
1979年 | 36篇 |
1978年 | 26篇 |
1976年 | 27篇 |
1975年 | 31篇 |
1974年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
151.
152.
Q.-Y. Shao A.-D. Li J.-B. Cheng H.-Q. Ling D. Wu Z.-G. Liu N.-B. Ming C. Wang H.-W. Zhou B.-Y. Nguyen 《Applied Physics A: Materials Science & Processing》2005,81(6):1181-1185
LaAlO3 (LAO) gate dielectric films were deposited on Si substrates by low-pressure metalorganic chemical vapor deposition. The interfacial structure and composition distribution were investigated by high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), secondary-ion mass spectroscopy (SIMS), and Auger-electron spectroscopy (AES). HRTEM confirms that there exists an interfacial layer between LAO and Si in most samples. AES, SIMS, and XPS analyses indicate that the interfacial layer is compositionally graded La–Al silicate and the Al element is severely deficient close to the Si surface. Electrical properties of LAO films were evaluated. No evident difference in electrical properties between samples with and without native SiO2 layers was observed. The electrical properties are discussed in terms of LAO growth mechanisms, in relation to the interfacial structure. PACS 73.40.Qv; 81.15.Gh; 77.55.+f; 68.35.-p 相似文献
153.
基于SUN5500小型计算机并行开发环境,给出了消息传递模型和蕴式行模型的实现方法,通过实例分析了SUNMPI实际编程,并对选取不同模型有不同参数的运算时间进行了比较,结果表明,在SUN5500计算机上MPI模型和蕴式并行模型均能较大地提高运算速度,而且MPI在灵活性和并行程度方面更优。 相似文献
154.
关于多线性振荡奇异积分在加权Hardy-型空间上的一致估计 总被引:1,自引:0,他引:1
本文对一类具有光滑位相函数的多线性振荡奇异积分算子建立了一致的加权(H^1(R^n),L^1(R^n))估计及一致的加权(HKp(R^n),Kp(R^n)估计。 相似文献
155.
Tao Jin Feng-Xian Jiang Xiao-Li Li Fang Wang Xiao-Hua Shen Rui-Qiang Zhang Hai-Shun Wu 《Applied Surface Science》2006,253(5):2708-2712
CoPt/Ag and [C/CoPt]n/Ag thin films have been prepared onto the glass substrates by magnetron sputtering. We investigated the evolution of texture and magnetic properties of CoPt/Ag and [C/CoPt]n/Ag films. The results show that C-doping plays an important role in improving (0 0 1) texture, improving the order parameter S, reducing the intergrain interactions, and making the magnetization reversal mechanism more close to Stoner-Wolfarth rotational mechanism. The growth mechanism of (0 0 1) texture also seems to be related strongly to the films thickness. Our results show that the highly (0 0 1)-oriented films with ordered fct phase have a significant potential for the perpendicular media of extremely high-density recording. 相似文献
156.
157.
158.
Investigation of remelting and cladding processing with laminar plasma jets on several metals has been conducted looking for possible development of a new surface modification technique. The remelting tests illustrated that the new method could evidently improve the material microstructure and properties of cast iron. The cladding was done with Al2O3 ceramic powder on stainless steel. The energy dispersive spectra (EDS) analysis was used to determine the distribution of the major cladding element in the plasma-processed layers, for which the microstructure observations and hardness measurements were also performed. 相似文献
159.
160.
The influence of the electron-LO-phonon coupling on energy spectrum of the low-lying states ofan exciton inparabolic quantum dots is investigated as a function of dot size. Calculations are made by using the method of few-bodyphysics within the effective-mass approximation. A considerable decrease of the energy in the stronger confinement rangeis found for the low-lying states of an exciton in quantum dots, which results from the confinement of electron-phononcoupling. 相似文献