全文获取类型
收费全文 | 292187篇 |
免费 | 7323篇 |
国内免费 | 5120篇 |
专业分类
化学 | 162118篇 |
晶体学 | 4794篇 |
力学 | 13305篇 |
综合类 | 333篇 |
数学 | 30570篇 |
物理学 | 93510篇 |
出版年
2022年 | 2714篇 |
2021年 | 3435篇 |
2020年 | 3883篇 |
2019年 | 4232篇 |
2018年 | 4867篇 |
2017年 | 4874篇 |
2016年 | 6675篇 |
2015年 | 4467篇 |
2014年 | 6806篇 |
2013年 | 13667篇 |
2012年 | 11229篇 |
2011年 | 12983篇 |
2010年 | 9612篇 |
2009年 | 9566篇 |
2008年 | 11257篇 |
2007年 | 10844篇 |
2006年 | 10143篇 |
2005年 | 9088篇 |
2004年 | 8270篇 |
2003年 | 7525篇 |
2002年 | 7443篇 |
2001年 | 8450篇 |
2000年 | 6432篇 |
1999年 | 5006篇 |
1998年 | 4163篇 |
1997年 | 3943篇 |
1996年 | 3785篇 |
1995年 | 3434篇 |
1994年 | 3408篇 |
1993年 | 3189篇 |
1992年 | 3820篇 |
1991年 | 3761篇 |
1990年 | 3688篇 |
1989年 | 3633篇 |
1988年 | 3529篇 |
1987年 | 3552篇 |
1986年 | 3378篇 |
1985年 | 4110篇 |
1984年 | 4135篇 |
1983年 | 3347篇 |
1982年 | 3417篇 |
1981年 | 3375篇 |
1980年 | 3135篇 |
1979年 | 3591篇 |
1978年 | 3582篇 |
1977年 | 3680篇 |
1976年 | 3613篇 |
1975年 | 3260篇 |
1974年 | 3250篇 |
1973年 | 3216篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
N. A. Anurova V. A. Blatov G. D. Ilyushin O. A. Blatova A. K. Ivanov-Shitz L. N. Demyanets 《Crystallography Reports》2008,53(6):930-936
A new method was developed for studying voids and channels in crystal structures based on the Voronoi-Dirichlet partition
of crystal space, and 822 structurally characterized ternary compounds Li
p
X
q
O
r
were analyzed for the first time. For these compounds, the dimensionality was determined and the migration patterns of channel
systems capable of providing lithium-ion transport were constructed. The calculated coordinates of lithium atoms in the centers
of the voids are consistent (within 0.4 ?) with the known structural data. Among these compounds, 113 compounds have infinite
channel systems, 60 compounds (18 structural types, STs) have been described earlier in the literature as solid electrolytes,
and 53 compounds (23 STs) can be considered as potential one-, two-, or three-dimensional ionic conductors (13, 3, and 7 STs,
respectively).
Original Russian Text ? N.A. Anurova, V.A. Blatov, G.D. Ilyushin, O.A. Blatova, A.K. Ivanov-Shitz, L.N. Dem’yanets, 2008,
published in Kristallografiya, 2008, Vol. 53, No. 6, pp. 987–993. 相似文献
22.
K. Morigaki K. Takeda H. Hikita C. Ogihara P. Roca i Cabarrocas 《Journal of Non》2008,354(19-25):2131-2134
Our model for light-induced defect creation in hydrogenated amorphous silicon is applied to its kinetics, i.e., the growing curve of light-induced dangling bond density as a function of illumination time, which is fitted to a stretched exponential function. Two parameters β and τ involved in the function are estimated as functions of saturated dangling bond density in terms of our model. These are compared with two experimental results, i.e., our results obtained from ESR measurements and Shimakawa et al.’s results obtained from photoconductivity measurements. The saturated dangling bond density is also measured as a function of the generation rate of free carriers. The experimental results are compared with calculated results and discussed. 相似文献
23.
Some possible errors in determining the gravity anomalies are discussed. Such errors may be caused by an inaccurate calibration of the gravimeter used in an airborne survey system. An approach based on wavelet decompositions is proposed for its additional calibration with the use of flight data obtained during repeated flights. 相似文献
24.
Trabecular bone fracture is closely related to the trabecular architecture, microdamage accumulation, and bone tissue properties. Primary constituents of trabecular tissue are hydroxyapatite (HA) mineralized type-I collagen fibers. In this research, dynamic fracture in two dimensional (2-D) micrographs of ovine (sheep) trabecular bone is modeled using the mesoscale cohesive finite element method (CFEM). The bone tissue fracture properties are obtained based on the atomistic strength analyses of a type-I collagen + HA interfacial arrangement using molecular dynamics (MD). Analyses show that the presented framework is capable of analyzing the architecture dependent fracture in 2-D micrographs of trabecular bone. 相似文献
25.
The aim of this study is to construct a quantitative characteristic for the degree of gaze stabilization on a visual target with consideration of physiological constraints. A quality criterion for visual tracking during optokinetic vestibulocervical nystagmus is proposed. The index of imaginary tracking during rotation in the dark allows one to speak of a difference in the image stabilization quality between a healthy person and a patient. Experimental nystagmus data are used to calculate the quality index of visual tracking and the index of imaginary tracking. 相似文献
26.
A. V. Ivanov M. Yu. Tsentalovich E. G. Kogan L. G. Tomilova N. S. Zefirov 《Russian Chemical Bulletin》2008,57(8):1676-1679
The chlorination of benzene, toluene, and o-xylene with molecular chlorine in the presence of the phthalocyanine complexes of different structures was studied. The transformations
of the catalysts during the reaction were investigated.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1644–1647, August, 2008. 相似文献
27.
28.
M. K. Bratenko Yu. V. Kadel’nik V. A. Chornous M. V. Vovk 《Russian Journal of Organic Chemistry》2008,44(2):247-250
Oximes of 4-(4-pyrazolyl)-3-buten-2-onees obtained by successive reaction of 3-aryl-4-formylpyrazoles with acetone and hydroxylamine at the treatment with iodine suffered an oxidative cyclization yielding 3-aryl-4-(5-isoxazolyl)pyrazoles. 相似文献
29.
30.
K. S. Trofimova V. G. Dronov N. S. Shaglaeva R. G. Sultangareev 《Russian Journal of Applied Chemistry》2008,81(4):730-731
Possibilities of utilization of by-products formed in manufacture of epichlorohydrin are considered. A promising way to utilize wastes from production of epichlorohydrin by synthesis of 2,3-dichloropropene from 1,2,3-trichloropropane is suggested. 相似文献