全文获取类型
收费全文 | 233038篇 |
免费 | 1997篇 |
国内免费 | 800篇 |
专业分类
化学 | 116853篇 |
晶体学 | 3996篇 |
力学 | 10757篇 |
综合类 | 1篇 |
数学 | 25505篇 |
物理学 | 78723篇 |
出版年
2020年 | 1788篇 |
2019年 | 2043篇 |
2018年 | 2719篇 |
2017年 | 2651篇 |
2016年 | 3913篇 |
2015年 | 2391篇 |
2014年 | 3970篇 |
2013年 | 10074篇 |
2012年 | 7530篇 |
2011年 | 9396篇 |
2010年 | 6684篇 |
2009年 | 6628篇 |
2008年 | 8703篇 |
2007年 | 8733篇 |
2006年 | 8272篇 |
2005年 | 7492篇 |
2004年 | 6917篇 |
2003年 | 6111篇 |
2002年 | 6060篇 |
2001年 | 7092篇 |
2000年 | 5372篇 |
1999年 | 4236篇 |
1998年 | 3563篇 |
1997年 | 3472篇 |
1996年 | 3293篇 |
1995年 | 3008篇 |
1994年 | 2951篇 |
1993年 | 3042篇 |
1992年 | 3151篇 |
1991年 | 3332篇 |
1990年 | 3086篇 |
1989年 | 3028篇 |
1988年 | 3067篇 |
1987年 | 2956篇 |
1986年 | 2800篇 |
1985年 | 3809篇 |
1984年 | 4006篇 |
1983年 | 3200篇 |
1982年 | 3410篇 |
1981年 | 3336篇 |
1980年 | 3230篇 |
1979年 | 3335篇 |
1978年 | 3422篇 |
1977年 | 3350篇 |
1976年 | 3449篇 |
1975年 | 3141篇 |
1974年 | 3150篇 |
1973年 | 3195篇 |
1972年 | 2236篇 |
1971年 | 1849篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
191.
T. Wagner J. Gutwirth P. Nemec M. Frumar T. Wagner M. Vlcek V. Perina A. Mackova V. Hnatovitz 《Applied Physics A: Materials Science & Processing》2004,79(4-6):1561-1562
The pulsed laser deposition technique has been applied to prepare amorphous ternary AgSbS films. The films were prepared from AgSbS2 bulk glass using a KrF excimer laser. The composition of prepared films according to the results of the energy dispersive X-ray analysis and the Rutherford backscattering was close to bulk one. Optical transmission and spectral dependence of the refractive index proved the good optical quality of the films. The Ar+ ion laser dot exposures of the films show a potential applicability of the films as a new type of optical recording material. PACS 78.66.Jg; 81.15.Fg; 81.40.Wx 相似文献
192.
M. Tscherneck J. Kleinert C. Haimberger M. E. Holmes N. P. Bigelow 《Applied physics. B, Lasers and optics》2005,80(6):639-643
Ultracold molecules have been produced by photoassociation of Cs atoms trapped in a mirror magneto-optical trap. The molecules
were detected by resonantly enhanced multi-photon ionization followed by time-of-flight mass spectroscopy. The time-of-flight
ofatomic and molecular ions was investigated in the presence of a dc bias voltageapplied to the conducting mirror. This technique
provides a new tool for determining the distance between the cold molecules and the mirror surface.
This revised version was published online in August 2005 with a corrected cover date. 相似文献
193.
A. Di Maio A. Rocco P. Ferraro M. De Rosa P. De Natale S. De Nicola A. Finizio G. Pierattini G. Coppola M. Iodice V. Striano 《Optics and Lasers in Engineering》2007,45(3):385
In view of the growing interest for non-destructive tests of materials, geodynamical monitoring and in general remote sensing, there is a great effort to bring practical optical sensors from research labs to industrial and environmental applications. In this paper, we employ digital holographic technique as an efficient tool for evaluating the strain measurement capability of fiber Bragg gratings (FBG). A cantilever beam has been employed as a test structure under loading test. The strain measurements results obtained by fiber-based sensors have been compared to those obtained by using full-field digital holographic technique and point-wise strain gauge sensors glued on the same cantilever beam. A simple theoretical model is also presented to interpret and compare the experimental results coming from different techniques. 相似文献
194.
195.
P. N. Sapozhnikov 《Journal of Mathematical Sciences》1991,53(6):578-582
An analog of a sufficient statistic is proposed in the finite-dimensional linear space of statistics. It is shown that the unbiased estimator of the linear function of a parameter closest to a given function, expressed in terms of a minimal linearly sufficient statistic, is potentially unbiased and optimal.Translated from Statisticheskie Metody Otsenivaniya i Proverki Gipotez, pp. 51–58, 1986. 相似文献
196.
V. I. Bliznikas A. P. Norden B. N. Shapukov A. P. Shirokov 《Journal of Mathematical Sciences》1991,55(6):2091-2100
Biographical information on the eminent Soviet geometer Boris Lukich Laptev (4/23/05–1/15-89) is given as well as a survey of his research in the areas of differential geometry and history of mathematics.Translated from Itogi Nauki i Tekhniki, Seriya Problemy Geometrii, Vol. 21, pp.27–42, 1989. 相似文献
197.
A datalogger was developed to identify vocalizing dolphins within socially interacting captive groups. Every 50 ms the logger stores data on the level and frequency of detected sound. Dataloggers are temporarily attached to dolphins by suction cups for data collection sessions lasting up to 45 min. Later, computer analysis of data from the dataloggers reveals which dolphin produced each vocalization recorded during the session. Results from use of dataloggers with two captive bottlenose dolphins (Tursiops truncatus) at the New England Aquarium in Boston, MA are presented. The possible use of dataloggers with wild dolphins is discussed. 相似文献
198.
Pál Sohár Gábor Bernáth Géza Stájer Angela E. Szabo 《Magnetic resonance in chemistry : MRC》1989,27(9):872-876
Pentacyclic isoxazolines were obtained by the cycloaddition of benzonitrile oxide to norbornene-azetidinone-fused 3,1-oxazines. The constitutions of two of the isomers obtained, and the configurations and conformations of all products, were determined by means of 1H and 13C NMR spectroscopy and DNOE experiments. 相似文献
199.
200.
We investigated the morphological, structural and electronic properties of Pentacene thin films grown by vacuum thermal evaporation on different inert substrates at room temperature. The results of our AFM and STM analysis give an interplanar spacing of 1.54 nm corresponding to the (0 0 1) distance of the so-called “thin film phase”. The STS measurements show an HOMO-LUMO gap of 2.2 eV. 相似文献