全文获取类型
收费全文 | 8132篇 |
免费 | 1475篇 |
国内免费 | 1016篇 |
专业分类
化学 | 5860篇 |
晶体学 | 124篇 |
力学 | 448篇 |
综合类 | 53篇 |
数学 | 1143篇 |
物理学 | 2995篇 |
出版年
2024年 | 28篇 |
2023年 | 175篇 |
2022年 | 329篇 |
2021年 | 284篇 |
2020年 | 312篇 |
2019年 | 302篇 |
2018年 | 262篇 |
2017年 | 273篇 |
2016年 | 427篇 |
2015年 | 421篇 |
2014年 | 561篇 |
2013年 | 617篇 |
2012年 | 782篇 |
2011年 | 781篇 |
2010年 | 528篇 |
2009年 | 469篇 |
2008年 | 534篇 |
2007年 | 411篇 |
2006年 | 425篇 |
2005年 | 379篇 |
2004年 | 335篇 |
2003年 | 252篇 |
2002年 | 230篇 |
2001年 | 188篇 |
2000年 | 128篇 |
1999年 | 188篇 |
1998年 | 127篇 |
1997年 | 96篇 |
1996年 | 112篇 |
1995年 | 113篇 |
1994年 | 93篇 |
1993年 | 57篇 |
1992年 | 58篇 |
1991年 | 58篇 |
1990年 | 68篇 |
1989年 | 45篇 |
1988年 | 31篇 |
1987年 | 22篇 |
1986年 | 31篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1983年 | 14篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1928年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 301 毫秒
21.
22.
A multi-exposure of color fringes method has been developed to improve the capture speed of a conventional color CCD camera. In the method, four groups of projected fringe patterns encoded with different colors and different directions are stored in one CCD frame. Therefore the capture frequency of the conventional CCD can be improved to 200 Hz. It is available to measure the insect wings with low beating frequency, such as dragonfly, moth, or butterfly, whose beating frequency is about 30–40 Hz. We have used the method to measure the beating motion of a moth successfully. 相似文献
23.
利用国家同步辐射实验室合肥光源的真空紫外同步辐射,使NO分子和Ar原子混合物的超声分子束发生光电离,测量了Ar,NO和异类团簇Ar·NO的光电离效率谱. 在谱中,在与Ar原子的共振线对应的能量区域(11.5—12.0 eV)观察到一个强的类共振结构. 这个结果表明,在异类团簇Ar·NO的内部,稀有气体Ar原子的激发能转移到与它接触的分子NO上,使分子NO发生电离.
关键词:
Ar·NO团簇
同步辐射
光电离
能量转移 相似文献
24.
The orientation-selective growth of LaNiO3 films on Si(100) by pulsed laser deposition using a MgO buffer 总被引:4,自引:0,他引:4
X.Y. Chen K.H. Wong C.L. Mak J.M. Liu X.B. Yin M. Wang Z.G. Liu 《Applied Physics A: Materials Science & Processing》2002,75(4):545-549
Highly (100)-oriented, (110)-oriented and polycrystalline LaNiO3 (LNO) films were successfully prepared on Si(100) using an oriented MgO film as a buffer. It was somewhat surprising to find
that that the orientation relation between the LNO film and the corresponding MgO buffer was: LNO(100)\MgO(110), LNO(110)\MgO(111)
and LNO(polycrystalline)\MgO(100). The crystalline quality of the LNO films was shown to be sensitive to the preparation conditions
of the MgO buffer. The film surface was very smooth, without micrometer-sized droplets being observed. All LNO films were
of metallic conductivity, with a room-temperature resistivities of approximately 250, 280 and 420 μΩ cm for the (110)-oriented,
(100)-oriented and polycrystalline LNO, respectively.
Received: 2 April 2001 / Accepted: 23 October 2001 / Published online: 3 June 2002 相似文献
25.
A sample of 1233 events is used to study the general characteristics of {}^{16}O-Em interactions at 4.5 A GeV/c. Multiplicity and angular distributions of slow particles and correlations among them are discussed. The present data are compared with the corresponding results from the interactions of other projectiles at the same energy and also the same projectile at different energies. The results indicate that black particle production is independent of the energy and mass of the projectile, but for grey particles it is dependent on the mass of projectile. 相似文献
26.
Characterizations of Tb:Zn2SiO4 films on silicon wafer prepared by sol-gel dip-coating and solid-phase reaction
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Terbium-doped Zn_2SiO_4 films were successfully prepared on Si wafers by a simple sol-gel dip-coating and solid-phase reaction method of ZnO and SiO_2. X-ray diffraction (XRD) and UV-Vis absorption results revealed that films processed below 850℃ were ZnO in wurzite structure, and films processed above 850℃ were Zn_2SiO_4 in wellimite structure. Photoluminescence measurements of the Tb-doped Zn_2SiO_4 films showed two strong emission bands at 490 and 545nm. The photoluminescence lifetime was 4.6ms. 相似文献
27.
This paper presents a multiobjective hybrid metaheuristic approach for an intelligent spatial zoning model in order to draw territory line for geographical or spatial zone for the purpose of space control. The model employs a Geographic Information System (GIS) and uses multiobjective combinatorial optimization techniques as its components. The proposed hybrid metaheuristic consists of the symbiosis between tabu search and scatter search method and it is used heuristically to generate non-dominated alternatives. The approach works with a set of current solution, which through manipulation of weights are optimized towards the non-dominated frontier while at the same time, seek to disperse over the frontier by a strategic oscillation concept. The general procedure and its algorithms are given as well as its implementation in the GIS environment. The computation has resulted in tremendous improvements in spatial zoning. 相似文献
28.
Ching Sum Hui Lillian Sze Man Lam Chun Yin Wai Kin Chan Aleksandra B. Djurii 《Journal of polymer science. Part A, Polymer chemistry》2003,41(11):1708-1715
Polyurethanes incorporated with rhenium diimine complexes were synthesized. The polymers exhibited interesting morphologies and solution properties. Results from gel permeation chromatography suggested the formation of polymer aggregates in solutions. The polymers could act as probes for metal ions. The addition of metal ions to polymer solutions led to significant changes in the electronic absorption properties of the polymer solutions. This was attributed to the interactions between the polyether moieties and metal ions. The metal complexes could also act as efficient photosensitizers. After doping with charge‐transport viologens, the photoconductivity of the polymers was greatly enhanced. The experimental quantum efficiency was simulated with Onsager's theory. The thermalization distances and the primary yields were typically 12–14 Å and 10?3, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1708–1715, 2003 相似文献
29.
30.