全文获取类型
收费全文 | 29515篇 |
免费 | 125篇 |
国内免费 | 270篇 |
专业分类
化学 | 11150篇 |
晶体学 | 268篇 |
力学 | 1378篇 |
综合类 | 12篇 |
数学 | 8971篇 |
物理学 | 8131篇 |
出版年
2022年 | 122篇 |
2021年 | 127篇 |
2020年 | 50篇 |
2019年 | 40篇 |
2018年 | 1219篇 |
2017年 | 1474篇 |
2016年 | 768篇 |
2015年 | 581篇 |
2014年 | 506篇 |
2013年 | 710篇 |
2012年 | 3155篇 |
2011年 | 2343篇 |
2010年 | 1831篇 |
2009年 | 1555篇 |
2008年 | 585篇 |
2007年 | 636篇 |
2006年 | 606篇 |
2005年 | 4445篇 |
2004年 | 3917篇 |
2003年 | 2298篇 |
2002年 | 488篇 |
2001年 | 286篇 |
2000年 | 90篇 |
1999年 | 169篇 |
1998年 | 108篇 |
1997年 | 71篇 |
1996年 | 44篇 |
1995年 | 41篇 |
1994年 | 46篇 |
1992年 | 170篇 |
1991年 | 153篇 |
1990年 | 136篇 |
1989年 | 107篇 |
1988年 | 102篇 |
1987年 | 57篇 |
1986年 | 42篇 |
1985年 | 37篇 |
1984年 | 28篇 |
1983年 | 26篇 |
1979年 | 30篇 |
1976年 | 79篇 |
1975年 | 37篇 |
1974年 | 40篇 |
1973年 | 48篇 |
1972年 | 39篇 |
1970年 | 34篇 |
1969年 | 37篇 |
1968年 | 35篇 |
1967年 | 30篇 |
1966年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
In this paper, we give a short proof for the existence of nontrivial choreography solution to the equal-mass three-body problem,
which is discovered by Chenciner and Montgomery recently. 相似文献
992.
邓小刚 《中国科学A辑(英文版)》2002,45(3):356-370
Based on the method deriving dissipative compact linear schemes (DCS), novel high-order dissipative weighted compact nonlinear schemes (DWCNS) are developed. By Fourier analysis,the dissipative and dispersive features of DWCNS are discussed. In view of the modified wave number, the DWCNS are equivalent to the fifth-order upwind biased explicit schemes in smooth regions and the interpolations at cell-edges dominate the accuracy of DWCNS. Boundary and near boundary schemes are developed and the asymptotic stabilities of DWCNS on both uniform and stretching grids are analyzed. The multi-dimensional implementations for Euler and Navier-Stokes equations are discussed. Several numerical inviscid and viscous results are given which show the good performances of the DWCNS for discontinuities capturing, high accuracy for boundary layer resolutions, good convergent rates (the root-mean-square of residuals approaching machine zero for solutions with strong shocks) and especially the damping effect on the spudous oscillations which were found in the solutions obtained by TVD and ENO schemes. 相似文献
993.
Starting with an initial vector λ = (λ(κ))κ∈z ∈ ep(Z), the subdivision scheme generates asequence (Snaλ)∞n=1 of vectors by the subdivision operator Saλ(κ) = ∑λ(j)a(k - 2j), k ∈ Z. j∈zSubdivision schemes play an important role in computer graphics and wavelet analysis. It is very interesting tounderstand under what conditions the sequence (Snaλ)∞n=1 converges to an Lp-function in an appropriate sense.This problem has been studied extensively. In this paper we show that the subdivision scheme converges forany initial vector in ep(Z) provided that it does for one nonzero vector in that space. Moreover, if the integertranslates of the refinable function are stable, the smoothness of the limit function corresponding to the vectorλ is also independent of λ. 相似文献
994.
In the present paper, a liquid (or melt) film of relatively high temperature ejected from a vessel and painted on the moving
solid film is analyzed by using the second-order fluid model of the non-Newtonian fluid. The thermocapillary flow driven by
the temperature gradient on the free surface of a Newtonian liquid film was discussed before. The effect of rheological fluid
on thermocapillary flow is considered in the present paper. The analysis is based on the approximations of lubrication theory
and perturbation theory. The equation of liquid height and the process of thermal hydrodynamics of the non-Newtonian liquid
film are obtained, and the case of weak effect of the rheological fluid is solved in detail. 相似文献
995.
唐启鹤 《中国科学A辑(英文版)》2002,45(5):632-639
The famous Embrechts-Goldie-Veraverbeke formula shows that, in the classical Cramér-Lundberg risk model, the ruin probabilities satisfy \(R(x, \infty ) \sim \rho ^{ - 1} \bar F_e (x)\) if the claim sizes are heavy-tailed, where Fe denotes the equilibrium distribution of the common d.f. F of the i.i.d. claims, ? is the safety loading coefficient of the model and the limit process is for x → ∞. In this paper we obtain a related local asymptotic relationship for the ruin probabilities. In doing this we establish two lemmas regarding the n-fold convolution of subexponential equilibrium distributions, which are of significance on their own right. 相似文献
996.
The geophysical quantitative excitation on seasonal polar wobble of Earth Rotation has not been well achieved so far. The
atmospheric, hydrologic and oceanic angular momentum variations are investigated from monthly values simulated by a coupled
ocean-atmosphere general circulation model. The simulated equatorial AAM functions agree well with that from the JMA operational
analysis in 90°:E direction, but disagree along Greenwich meridian. As for the annual cycle, not only the hydrologic and oceanic
excitations partly match the residuals between geodetic functions of polar wobble and JMA AAM functions, but also the combinations
with NCEP and JMA analysis AAM functions are better than those estimated from NCAR-CSM1 climate model. 相似文献
997.
王立中 《中国科学A辑(英文版)》2002,45(12):1578-1581
In this paper, we focus on the structure of p-blocks with defect group satisfying some special condition. These special conditions
include: two elements of the defect group are conjugate to each other in defect D if and only if they are conjugate to each
other in G; the number of conjugacy classes whose p-part is contained in P by conjugacy is not larger than ∣P∣ 相似文献
998.
张跃辉 《中国科学A辑(英文版)》2002,45(6):741-748
Let A be a quasi-hereditary algebra with a strong exact Borel subalgebra. It is proved that for any standard semisimple subalgebra
T there exists an exact Borel subalgebra B of A such that T is a maximal semisimple subalgebra of B. It is shown that the
maximal length of flags of exact Borel subalgebras of A is the difference of the radium and the rank of Grothendic group of
A plus 2. The number of conjugation-classes of exact Borel subalgebras is 1 if and only if A is basic; the number is 2 if
and only if A is semisimple. For all other cases, this number is 0 or no less than 3. Furthermore, it is shown that all the
exact Borel subalgebras are idempotent-conjugate to each other, that is, for any exact Borel subalgebras B and C of A, there
exists an idempotent e of A, and an invertible element u of A, such that eBe = u-1eCeu. 相似文献
999.
Let ƒ and g be real-analytic functions near the origin in ℝ2. Given 1 < p < ∞, we obtain a characterization of the set of positive numbers ∈ and δ that ensures
for some small neighborhood K of the origin. A notion of stability is introduced in relation to Ap weights and a counterexample is presented to show that the two-dimensional weighted problem, unlike its analog in dimension
one, is not stable. 相似文献
1000.
Some equivalent characterizations for a skew group ring to be a Dubrovin valuation ring are given. Among them all the prime
ideals of a Dubrovin valuation skew group ring are characterised.
Received June 8, 1999, Revised June 4, 2001, Accepted July 20, 2001 相似文献