全文获取类型
收费全文 | 227699篇 |
免费 | 1928篇 |
国内免费 | 544篇 |
专业分类
化学 | 107075篇 |
晶体学 | 3419篇 |
力学 | 10324篇 |
综合类 | 10篇 |
数学 | 22487篇 |
物理学 | 65286篇 |
无线电 | 21570篇 |
出版年
2021年 | 2232篇 |
2020年 | 2317篇 |
2019年 | 2955篇 |
2018年 | 4048篇 |
2017年 | 4055篇 |
2016年 | 5390篇 |
2015年 | 2629篇 |
2014年 | 4846篇 |
2013年 | 9483篇 |
2012年 | 7503篇 |
2011年 | 8862篇 |
2010年 | 7160篇 |
2009年 | 7552篇 |
2008年 | 8706篇 |
2007年 | 8725篇 |
2006年 | 7778篇 |
2005年 | 6962篇 |
2004年 | 6589篇 |
2003年 | 6056篇 |
2002年 | 5979篇 |
2001年 | 6422篇 |
2000年 | 4938篇 |
1999年 | 3900篇 |
1998年 | 3364篇 |
1997年 | 3420篇 |
1996年 | 3094篇 |
1995年 | 2762篇 |
1994年 | 2839篇 |
1993年 | 2744篇 |
1992年 | 3024篇 |
1991年 | 3138篇 |
1990年 | 3063篇 |
1989年 | 3084篇 |
1988年 | 2940篇 |
1987年 | 2792篇 |
1986年 | 2634篇 |
1985年 | 3333篇 |
1984年 | 3349篇 |
1983年 | 2813篇 |
1982年 | 2728篇 |
1981年 | 2677篇 |
1980年 | 2489篇 |
1979年 | 2824篇 |
1978年 | 2790篇 |
1977年 | 2962篇 |
1976年 | 2970篇 |
1975年 | 2753篇 |
1974年 | 2682篇 |
1973年 | 2809篇 |
1972年 | 2145篇 |
排序方式: 共有10000条查询结果,搜索用时 553 毫秒
941.
Maria G. Semenova Larisa E. Belyakova Anna S. Antipova Yu. N. Polikarpov Lida Klouda Anna Markovic Michael M. Il'in 《Colloids and surfaces. B, Biointerfaces》2003,31(1-4):47-54
We report on the effect of commercially important polysaccharides (maltodextrins with variable dextrose equivalent (Paselli SA-2, MD-6 and MD-10) on the surface activity at the air–water interface of small-molecule surfactants (sms), possessing different hydrophobic–lipophilic balance ((SSL (Na+), the main component is a sodium salt of stearol–lactoyl lactic acid, and PGE (080), polyglycerol ester of C18 fatty acid), and widely used in food products. A marked change of the surface activity of sms was found in the presence of maltodextrins by tensiometry. The combined data of laser multiangle light scattering and mixing calorimetry have suggested that this result is governed by specific complex formation between maltodextrins and sms in aqueous medium. Measurements have been made of the molar mass, the second virial coefficient and the enthalpy of intermolecular interactions in aqueous solutions. The implication of a degree of polymerization of maltodextrins in this phenomenon was shown. The interrelation between the molecular parameters of the formed complexes and their surface activity at the air–water interface has been revealed and discussed. 相似文献
942.
943.
The logarithmic decrement and shear modulus of a bulk amorphous Zr52.5Ti5Cu17.9Ni14.6Al10 alloy were studied with an inverse torsion pendulum in the range from room temperature to the crystallization temperature and in the frequency range 5–40 Hz. The activation energy spectra of reversible and irreversible structural relaxation were estimated. The results obtained are discussed in the context of a two-energy-level model. 相似文献
944.
945.
946.
947.
T. M. Shneidman G. G. Adamian N. V. Antonenko S. P. Ivanova R. V. Jolos W. Scheid 《Physics of Atomic Nuclei》2003,66(2):206-217
Based on the dinuclear system concept, the role of bending vibrations in creation of the angular momentum of primary fission fragments is investigated. For 252Cf spontaneous fission, the angular momenta of the fragments are calculated as a function of the neutron multiplicity and compared with available experimental data. Different cluster compositions of the 252Cf fission modes at the scission point are considered. 相似文献
948.
P. M. Larionov A. N. Malov M. M. Mandrik N. A. Maslov A. M. Orishich 《Journal of Applied Spectroscopy》2003,70(1):38-42
We investigated the laser-induced fluorescence spectra (LIF) of porcine cardiac tissues with different degrees of viability. The data obtained are compared with the results of routine histological investigations and also with the experiments performed with the use of fluorescent probes. It has been found with a high degree of reliability that the loss of the viability of the myocardium tissue leads to the alteration of its LIF spectra. This can be used for low-invasive rapid control of transplant viability in the process of its preparation and during surgery. 相似文献
949.
Lasing and discharge in mixtures of SF6 with hydrogen and hydrocarbons are investigated. If the chemical reaction is initiated by a self-sustained discharge (a generator
with both an inductive and capacitive energy storage can be used), the maximum lasing efficiency is attained at high values
of the ratio E/p (where E is the electric field intensity and p is the pressure in the mixture) if shaped electrodes and preionization of the discharge gap are employed. For the first time,
the lasing efficiency obtained in a nonchain HF laser is as high as 10% of the energy deposit and 4.5% of the stored energy
for a specific radiation energy of ≈140 J/(l atm). At high efficiencies, the emission spectrum of the nonchain HF laser significantly
broadens and cascade lasing at P(3-2) → P(2-1) → P(1-0) vibrational transitions for several rotational lines is realized. 相似文献
950.
Baidyshev V. S. Udodov V. N. Popov A. A. Potekaev A. I. 《Russian Physics Journal》2003,46(12):1193-1198
The paper offers a method for calculating phase diagrams of polytype transformations in close-packed crystals based on the generalized axial Ising's model of finite dimensions at non-zero temperatures. Using the Metropolis algorithm, the behavior of systems with polytype transitions is studied under the conditions of changing external shear stress and temperature. The longest polytype period considered here is taken to be 30 close-packed planes. 相似文献