全文获取类型
收费全文 | 278730篇 |
免费 | 1603篇 |
国内免费 | 802篇 |
专业分类
化学 | 127836篇 |
晶体学 | 4139篇 |
力学 | 16873篇 |
综合类 | 10篇 |
数学 | 53271篇 |
物理学 | 79006篇 |
出版年
2021年 | 1971篇 |
2020年 | 2009篇 |
2019年 | 2568篇 |
2018年 | 13891篇 |
2017年 | 13702篇 |
2016年 | 10755篇 |
2015年 | 3149篇 |
2014年 | 4562篇 |
2013年 | 8858篇 |
2012年 | 10484篇 |
2011年 | 18256篇 |
2010年 | 11941篇 |
2009年 | 12531篇 |
2008年 | 14019篇 |
2007年 | 16096篇 |
2006年 | 6871篇 |
2005年 | 7146篇 |
2004年 | 7089篇 |
2003年 | 7067篇 |
2002年 | 6121篇 |
2001年 | 5825篇 |
2000年 | 4409篇 |
1999年 | 3267篇 |
1998年 | 2877篇 |
1997年 | 2891篇 |
1996年 | 2729篇 |
1995年 | 2321篇 |
1994年 | 2398篇 |
1993年 | 2315篇 |
1992年 | 2572篇 |
1991年 | 2704篇 |
1990年 | 2601篇 |
1989年 | 2678篇 |
1988年 | 2589篇 |
1987年 | 2608篇 |
1986年 | 2468篇 |
1985年 | 3078篇 |
1984年 | 3143篇 |
1983年 | 2631篇 |
1982年 | 2603篇 |
1981年 | 2565篇 |
1980年 | 2380篇 |
1979年 | 2751篇 |
1978年 | 2705篇 |
1977年 | 2888篇 |
1976年 | 2888篇 |
1975年 | 2680篇 |
1974年 | 2613篇 |
1973年 | 2736篇 |
1972年 | 2102篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
N. N. Pustovoitov 《Analysis Mathematica》2003,29(3):201-218
V stat'e izuchayutsya klassy periodicheskikh funktsii mnogikh peremennykh s zadannoi mazhorantoi smeshannykh modulei nepreryvnosti, prichem mazhoranta imeet spetsial'nyi vid. Rassmotreny nailuchshie priblizheniya ukazannykh klassov i vozmozhnost' kharakterizatsii 'etikh klassov cherez nailuchshie priblizheniya. 相似文献
112.
Florin Ambro 《manuscripta mathematica》2003,111(1):43-49
We prove a precise inversion of adjunction formula for the log variety (ℂ
d
+1,X), where X is a non-degenerate hypersurface. As a corollary, the minimal log discrepancies of non-degenerate normal hypersurface singularities
are bounded by dimension.
Received: 17 September 2002 / Revised version: 22 November 2002
Published online: 14 February 2003
Current address: DPMMS, CMS, University of Cambridge, Wilberforce Road, Cambridge CB3 0WB, England. e-mail: f.ambro@dpmms.cam.ac.uk
Mathematics Subject Classification (2000): Primary 14B05; Secondary 14M25, 52B20 相似文献
113.
Christiane Albrecht 《Analytical and bioanalytical chemistry》2008,390(5):1223-1224
114.
115.
Ricaurte Rodríguez Manuel Nogueras Justo Cobo John N. Low Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(7):o376-o378
Molecules of the title compound, C12H13ClN4, are linked by two independent N—H...N hydrogen bonds into a chain of edge‐fused R22(8) rings. The significance of this study lies in its attempt to rationalize the patterns of supramolecular aggregation in the title compound and in a range of analogous 4,6‐disubstituted 2‐aminopyrimidines. 相似文献
116.
A. P. Voronov G. N. Babenko V. M. Puzikov A. D. Roshal’ V. I. Salo 《Crystallography Reports》2008,53(4):708-712
The features of doping of KDP crystals with cerium ions and organocerium complexes with alizarin complexon and arsenazo III have been investigated. It is established that “direct” doping by introducing cerium salts into the initial solution cannot be implemented. The effect of organometallic complexes of cerium on the crystal growth has been studied. Organocerium complexes predominantly enter the prismatic or pyramidal growth sectors. It is shown that the complex arsenazo III + Ce blocks the growth of the prismatic sector. Cerium-doped KDP crystals exhibit a photoluminescence band peaking at the wavelength λmax= 350 nm. 相似文献
117.
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
118.
M.N. Ichchou J. Berthaut M. Collet 《International Journal of Solids and Structures》2008,45(5):1179-1195
This paper addresses the issue of energy propagation features in ribbed panels over a wide frequency range. First, a tool for estimating the wave propagation characteristics of one- and two-dimensional structures by k-space analysis is presented. This tool uses a concept of Inhomogeneous Wave Correlation with sparse measured or extracted data, and leads to the estimation of θ-dependent wavenumbers. Here, the method is employed with the sparse simulated and measured normal velocities of a set of ribbed panels and new insights into their k-space behavior are highlighted. Behavior is essentially characterized at low frequencies by structural orthotropy. Comparisons with homogenized data show very good agreement. At higher frequencies, a new behavior pattern is observed and explained both numerically and experimentally. This is a multi-modal waveguide type of propagation in a direction parallel to the ribs. 相似文献
119.
Chengzhi Qi Mingyang Wang Qihu Qian Jianjie Chen 《Moscow University Mechanics Bulletin》2008,63(5):113-121
The formation mechanisms for the structural hierarchy in geological media are discussed. It is shown that the formation of such a hierarchy is caused by certain external and internal circumstances. The first ones consist in the fact that, because of external actions, the Earth’s poles continuously execute the translational and rotational motions responsible for a regular structure of rock fracture and for the appearance of the scale factor √2. The second ones consist in the fact that, under the action of many random factors and because of external actions, during the formation of geological media there appear dissipative structures and, hence, some self-similar fractal structures are formed. 相似文献
120.
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