全文获取类型
收费全文 | 419532篇 |
免费 | 3001篇 |
国内免费 | 1274篇 |
专业分类
化学 | 200235篇 |
晶体学 | 6524篇 |
力学 | 23119篇 |
综合类 | 13篇 |
数学 | 70704篇 |
物理学 | 123212篇 |
出版年
2020年 | 3156篇 |
2019年 | 3767篇 |
2018年 | 15233篇 |
2017年 | 15054篇 |
2016年 | 13182篇 |
2015年 | 4713篇 |
2014年 | 7076篇 |
2013年 | 15323篇 |
2012年 | 15165篇 |
2011年 | 23685篇 |
2010年 | 15875篇 |
2009年 | 16443篇 |
2008年 | 19201篇 |
2007年 | 21131篇 |
2006年 | 11957篇 |
2005年 | 11651篇 |
2004年 | 11243篇 |
2003年 | 10822篇 |
2002年 | 9735篇 |
2001年 | 10121篇 |
2000年 | 7672篇 |
1999年 | 5784篇 |
1998年 | 4950篇 |
1997年 | 4866篇 |
1996年 | 4635篇 |
1995年 | 4155篇 |
1994年 | 4192篇 |
1993年 | 4031篇 |
1992年 | 4531篇 |
1991年 | 4583篇 |
1990年 | 4429篇 |
1989年 | 4448篇 |
1988年 | 4351篇 |
1987年 | 4363篇 |
1986年 | 4127篇 |
1985年 | 5323篇 |
1984年 | 5414篇 |
1983年 | 4634篇 |
1982年 | 4720篇 |
1981年 | 4522篇 |
1980年 | 4312篇 |
1979年 | 4762篇 |
1978年 | 4763篇 |
1977年 | 4883篇 |
1976年 | 4921篇 |
1975年 | 4662篇 |
1974年 | 4572篇 |
1973年 | 4821篇 |
1972年 | 3489篇 |
1971年 | 3066篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
O. N. Kozakov 《Optics and Spectroscopy》2002,93(4):598-602
A method of calculating the partial characteristics of radiation absorption by the components of light-scattering disperse layers is proposed. This method is based on statistical modeling (the Monte Carlo method). The absorptivities of photographic gelatin and silver bromide microcrystals and the corresponding distributions of the absorbed energy over the layer thickness are calculated using the example of an interaction between actinic radiation and silver halide photographic layers in the wavelength range λ=200–440 nm. The following structural parameters of the photographic layer are used in the calculation: the mean size of emulsion crystals d=0.5 μm; the polydispersity C V =25%; the volume concentrations C V =10, 20, and 30%; and the thickness of the emulsion layer H=10 μm. 相似文献
102.
A.N Bekrenev 《Journal of Physics and Chemistry of Solids》2002,63(9):1627-1631
An unusually high mobility of atoms under intensive impulse reactions is explained by the behavior of point defects at the shock wave front. It is shown that either a shock wave front or moving dislocations can capture the interstitials, or they can be thermally activated in the direction of the shock wave propagation. 相似文献
103.
104.
The buffer extracts (3S) of sclerotia of Sclerotinia sclerotiorum IFO 9395 contained mitogenic substance(s) to murine splenocytes (Shinohara et al. Chem. Pharm. Bull., 38, 2219 (1990)). Although the native 3S was slightly mitogenic, heating of 3S induced significant mitogenic activity. To isolate the mitogen, we separated 3S by ion-exchange and gel filtration chromatographies. The isolated mitogen, named sclerogen, has a molecular mass of 32 kilodaltons (kDa) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and the isoelectric point (pI) of 5.9 by chromatofocusing. Sclerogen was significantly mitogenic in vitro against murine splenocytes after heat denaturation, and also showed the augmentation of the primary mixed lymphocyte reaction (MLR) in vitro. However, sclerogen did not show the activation of an alternative pathway of complement and hemagglutination activity. These results suggest that sclerogen is a unique mitogen which differs from lectins and shows mitogenicity after heat denaturation. 相似文献
105.
A. I. Bril' V. P. Kabashnikov N. V. Kuz'mina Yu. V. Khodyko 《Journal of Applied Spectroscopy》1991,55(3):934-939
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 3, pp. 478–484, September, 1991. 相似文献
106.
Large fault-tolerant interconnection networks 总被引:5,自引:0,他引:5
This paper deals with reliability and fault-tolerant properties of networks. We first survey general reliability properties of networks, in particular those concerning diameter vulnerability. Then we study in details reliability properties of some families of networks in particular de Bruijn and Kautz networks and their generalizations which appear as very good fault-tolerant networks. 相似文献
107.
108.
B. R. Harvey M. B. Lovett S. J. Boggis 《Journal of Radioanalytical and Nuclear Chemistry》1987,115(2):357-368
Selected experiences in the control of contamination and the threat it poses to the quality of analytical date are discussed in the context of the whole analytical process from collection of marine environmental samples, through handling and radiochemical separation, to the final interpretation of results. Examples include a demonstration of the contamination introduced during sediment core sectioning, contamination of sea water by a ship's pumping system, and the effect of filtration on the apparent partitioning of radionuclides between solid and liquid phases of sea water. 相似文献
109.
110.
The acoustic field inside a shell excited by a spatially inhomogeneous harmonic pressure field is studied. The shell is assumed
to have a finite length, a set of orthogonal stiffening ribs, two ends bounding the acoustic volume, and a sound-insulating
structure, which includes layers of sound-insulating material, resonant elements, and an interior panel. The shell is considered
to be orthotropic with boundary conditions corresponding to a free support. For the acoustic field in the closed volume, analytical
expressions are derived with allowance for the elastoacoustic interaction of the shell with the sound-insulating layers and
with the medium both inside the shell (with arbitrary impedance values at the ends) and outside it. These expressions are
used to investigate the effect of different types of resonant systems on the sound field inside the shell. 相似文献