全文获取类型
收费全文 | 7543篇 |
免费 | 199篇 |
国内免费 | 6篇 |
专业分类
化学 | 4377篇 |
晶体学 | 26篇 |
力学 | 142篇 |
综合类 | 1篇 |
数学 | 1030篇 |
物理学 | 2172篇 |
出版年
2020年 | 58篇 |
2018年 | 57篇 |
2017年 | 62篇 |
2016年 | 158篇 |
2015年 | 113篇 |
2014年 | 143篇 |
2013年 | 299篇 |
2012年 | 284篇 |
2011年 | 320篇 |
2010年 | 168篇 |
2009年 | 142篇 |
2008年 | 269篇 |
2007年 | 278篇 |
2006年 | 226篇 |
2005年 | 236篇 |
2004年 | 174篇 |
2003年 | 171篇 |
2002年 | 128篇 |
2001年 | 115篇 |
2000年 | 101篇 |
1999年 | 94篇 |
1998年 | 70篇 |
1997年 | 96篇 |
1996年 | 97篇 |
1995年 | 108篇 |
1994年 | 102篇 |
1993年 | 100篇 |
1992年 | 103篇 |
1991年 | 87篇 |
1990年 | 81篇 |
1989年 | 86篇 |
1988年 | 81篇 |
1987年 | 87篇 |
1986年 | 83篇 |
1985年 | 102篇 |
1984年 | 113篇 |
1983年 | 79篇 |
1982年 | 110篇 |
1981年 | 108篇 |
1980年 | 84篇 |
1979年 | 89篇 |
1978年 | 115篇 |
1977年 | 105篇 |
1976年 | 95篇 |
1975年 | 93篇 |
1974年 | 72篇 |
1973年 | 90篇 |
1971年 | 62篇 |
1967年 | 57篇 |
1966年 | 57篇 |
排序方式: 共有7748条查询结果,搜索用时 953 毫秒
61.
High frequency acoustic measurements have been performed at temperatures around the freezing pointT
c
in a cobalt insulating spin-glass. Assuming a Waller coupling mechanism between the spins and the acoustic wave, the data are interpreted in the framework of a dynamical model which takes into account the modulation of the reaction field. As a result, at the freezing temperature the characteristic relaxation time has no anomaly while the relevant susceptibility presents a maximum. The peculiar frequency dependence (as 1/2) atT
c
of the complex elastic constant is experimentally put in evidence.Associated with the Centre National de la Recherche Scientifique (UA 789) 相似文献
62.
63.
Some consequences of a model whereN=1 supersymmetry is realized nonlinearly are worked out forep-collisions at HERA-energies. The model contains in addition to the standard particles one Goldstone-fermion λ, a neutrino-like Majoranaparticle. The existence of such a particle would be signalled by events with large missing energy and momentum. We present detailed predictions for the following special kinematic regions: (1) events with a tagged small angle electron and a largeE T jet, (2) events with a large angle electron and a small angle tagged exclusive proton, (3) events with a tagged small angle electron and a tagged small angle exclusive proton. We indicate the region in coupling constant and mass of the Goldstone-fermion which can be explored at HERA and compare with the limits obtainable from existing data one + e ? and \(p\bar p\) collisions at high energies. 相似文献
64.
A. Türler H. W. Gäggeler D. T. Jost P. Armbruster W. Brüchle H. Folger F. P. Heßberger S. Hofmann G. Münzenberg V. Ninov M. Schädel K. Sümmerer J. V. Kratz U. Scherer 《Zeitschrift für Physik A Hadrons and Nuclei》1988,331(3):363-364
The isotope254No was produced in the fusion reaction48Ca +208Pb. Using the velocity filter SHIP and radiochemical techniques it was found that the nuclide254No with a half-life of 55 s decays byα, EC, and spontaneous-fission. Deduced partial half-lives are (61±2) s forα-decay, (550 ?160 +370 ) s for EC and [2.2 ?1.0 +2.0 ]×104 s for spontaneous fission. 相似文献
65.
I. Miesiąc K. Schügerl J. Szymanowski 《Journal of Radioanalytical and Nuclear Chemistry》1992,163(1):181-191
Potassium leakage was studied in liquid membrane systems containing various emulsifiers and compared with emulsion, stability in the storage test. The effects of various parameters upon emulsion stability and the leakage of standard traces are discussed. The transfer of cations can be caused by emulsion breaking, by transport with the specific carrier and/or with surfactants used as emulsifiers. The latter case becomes especially important when hydrophilic surfactants, e.g. ones containing polyoxyethylene chains, are present in liquid membranes. In systems containing hydrophobic emulsifiers the transfer of potassium is relatively low. In each case considered the effect of emulsifiers upon the transfer of the standard tracer should be checked prior to using the leakage test to characterize emulsion stability. 相似文献
66.
67.
M. Steyer K. A. Stankov H. Mizoguchi B. Ouyang F. P. Schäfer 《Applied physics. B, Lasers and optics》1989,49(4):331-337
An X-ray preionized, discharge-pumped XeCl laser with a variable beam cross-section of up to 6×6 cm2 is described. It uses flat electrodes and the beam width is determined by X-ray collimation. Its operation characteristics concerning reduced electric field strength (E/p) and X-ray dose are discussed in detail. The inductance of the discharge loop is minimized using a water capacitor arrangement. A very high specific optical power (90 MW/l) is achieved in an active volume of 1.2 l. The pulse energy exceeds 5 J in a 45 ns pulse (FWHM). Komatsu Ltd., Manda 1200, Hiratsuka-shi, Kanagawa 254, Japan Institute of Optics and Fine Mechanics, Department of Plasma Physics, Academia Sinica, Shanghai, P.R. China 相似文献
68.
B. Freisinger U. Kogelschatz J. H. Schäfer J. Uhlenbusch W. Viöl 《Applied physics. B, Lasers and optics》1989,49(2):121-129
Ozone is generated in pure oxygen (p5 kPa), synthetic air (p7 kPa) and oxygen-argon mixtures (p3 kPa) by irradiation of these gases with the VUV light of a repetitively pulsed (f
L15 Hz) F2-laser at =157.6 nm with maximum about 4 mJ/pulse. An absorption photometer measurement operating at 253.7 nm (Hg line) determines the ozone concentration as a function of oxygen and/or additive gas pressure, the repetition frequency of the laser and the wall temperature of the reaction chamber. The temporal development of the ozone concentration as a function of these parameters is calculated by means of rate equations for the species O(3
P), O2(X
3
g
–
), O3(1
A
1), O(1
D), O2(a
1g), O2(b
1
g
+
) and vibrationally excited O
3
*
(1
A
1) and the photon distribution. The maximum concentration of O3 in the sealed-off chamber reaches 1.6% in pure O2, 4.1% in air and 1.2% in a 1:5 O2-Ar mixture at 3 kPa. The annihilation of O3 by the wall and temperature dependent volume processes (300 KT395 K) is studied and the experimental and theoretical results are compared. 相似文献
69.
C. Fischbacher K.-U. Jagemann K. Danzer U. A. Müller L. Papenkordt J. Schüler 《Analytical and bioanalytical chemistry》1997,359(1):78-82
Partial least-squares regression (PLS) and radial basis function (RBF) networks are used to compute calibration models for non-invasive blood glucose determination by NIR diffuse reflectance spectroscopy. A model computation shows that even extremely small deviations of the spectra induce increased prediction errors. Since the spectral contribution of blood glucose is much smaller than deviations resulting from the non-invasive measuring process a method based on Pearson’s correlation coefficient can be used for evaluating the quality of the recorded spectra during the prediction step. Another method is based on the leverage values from the hat matrix of the RBF network. Both methods lead to a significant decrease in prediction error. 相似文献
70.