全文获取类型
收费全文 | 152031篇 |
免费 | 13182篇 |
国内免费 | 9051篇 |
专业分类
化学 | 44141篇 |
晶体学 | 1986篇 |
力学 | 11652篇 |
综合类 | 1794篇 |
数学 | 54910篇 |
物理学 | 59781篇 |
出版年
2023年 | 783篇 |
2022年 | 1391篇 |
2021年 | 2446篇 |
2020年 | 2355篇 |
2019年 | 2729篇 |
2018年 | 2518篇 |
2017年 | 2384篇 |
2016年 | 2657篇 |
2015年 | 2300篇 |
2014年 | 4177篇 |
2013年 | 7181篇 |
2012年 | 4517篇 |
2011年 | 5714篇 |
2010年 | 6045篇 |
2009年 | 11119篇 |
2008年 | 12164篇 |
2007年 | 10717篇 |
2006年 | 9369篇 |
2005年 | 7124篇 |
2004年 | 6588篇 |
2003年 | 6517篇 |
2002年 | 9397篇 |
2001年 | 5808篇 |
2000年 | 5346篇 |
1999年 | 4959篇 |
1998年 | 4308篇 |
1997年 | 3268篇 |
1996年 | 2961篇 |
1995年 | 3176篇 |
1994年 | 3004篇 |
1993年 | 2414篇 |
1992年 | 1941篇 |
1991年 | 1452篇 |
1990年 | 1234篇 |
1989年 | 1006篇 |
1988年 | 972篇 |
1987年 | 723篇 |
1986年 | 543篇 |
1985年 | 1390篇 |
1984年 | 968篇 |
1983年 | 706篇 |
1982年 | 1015篇 |
1981年 | 1142篇 |
1980年 | 1013篇 |
1979年 | 908篇 |
1978年 | 800篇 |
1977年 | 684篇 |
1976年 | 651篇 |
1974年 | 390篇 |
1973年 | 533篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
31.
We numerically solve the time-dependent Ginzburg–Landau equations for two-gap superconductors using the finite-element technique. The real-time simulation shows that at low magnetic field, the vortices in small-size samples tend to form clusters or other disorder structures. When the sample size is large, stripes appear in the pattern. These results are in good agreement with the previous experimental observations of the intriguing anomalous vortex pattern, providing a reliable theoretical basis for the future applications of multi-gap superconductors. 相似文献
32.
33.
34.
35.
Bobby Wilson 《偏微分方程通讯》2015,40(8):1521-1542
This article explores the questions of long time orbital stability in high order Sobolev norms of plane wave solutions to the NLSE in the defocusing case. 相似文献
36.
Leonor Contreras Ignacio Villarroel Camila Torres Roberto Rozas 《Molecules (Basel, Switzerland)》2021,26(6)
Doxorubicin (DOX), a recognized anticancer drug, forms stable associations with carbon nanotubes (CNTs). CNTs when properly functionalized have the ability to anchor directly in cancerous tumors where the release of the drug occurs thanks to the tumor slightly acidic pH. Herein, we study the armchair and zigzag CNTs with Stone–Wales (SW) defects to rank their ability to encapsulate DOX by determining the DOX-CNT binding free energies using the MM/PBSA and MM/GBSA methods implemented in AMBER16. We investigate also the chiral CNTs with haeckelite defects. Each haeckelite defect consists of a pair of square and octagonal rings. The armchair and zigzag CNT with SW defects and chiral nanotubes with haeckelite defects predict DOX-CNT interactions that depend on the length of the nanotube, the number of present defects and nitrogen doping. Chiral nanotubes having two haeckelite defects reveal a clear dependence on the nitrogen content with DOX-CNT interaction forces decreasing in the order 0N > 4N > 8N. These results contribute to a further understanding of drug-nanotube interactions and to the design of new drug delivery systems based on CNTs. 相似文献
37.
Comparative study on transport properties of N-, P-, and As-doped SiC nanowires: Calculated based on first principles
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
According to the one-dimensional quantum state distribution, carrier scattering, and fixed range hopping model, the structural stability and electron transport properties of N-, P-, and As-doped SiC nanowires(N-SiCNWs, P-SiCNWs, and As-SiCNWs) are simulated by using the first principles calculations. The results show that the lattice structure of NSiCNWs is the most stable in the lattice structures of the above three kinds of doped SiCNWs. At room temperature,for unpassivated SiCNWs, the doping effect of P and As are better than that of N. After passivation, the conductivities of all doped SiCNWs increase by approximately two orders of magnitude. The N-SiCNW has the lowest conductivity. In addition, the N-, P-, As-doped SiCNWs before and after passivation have the same conductivity–temperature characteristics,that is, above room temperature, the conductivity values of the doped SiCNWs all increase with temperature increasing.These results contribute to the electronic application of nanodevices. 相似文献
38.
Recent Progress in the $L_p$ Theory for Elliptic and Parabolic Equations with Discontinuous Coefficients
下载免费PDF全文
![点击此处可从《分析论及其应用》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hongjie Dong 《分析论及其应用》2020,36(2):161-199
In this paper, we review some results over the last 10-15 years on elliptic and parabolic equations with discontinuous coefficients. We begin with an approach given by N. V. Krylov to parabolic equations in the whole space with $\rm{VMO}_x$ coefficients. We then discuss some subsequent development including elliptic and parabolic equations with coefficients which are allowed to be merely measurable in one or two space directions, weighted $L_p$estimates with Muckenhoupt ($A_p$) weights, non-local elliptic and parabolic equations, as well as fully nonlinear elliptic and parabolic equations. 相似文献
39.
This paper deals with the Cauchy–Dirichlet problem for the fractional Cahn–Hilliard equation. The main results consist of global (in time) existence of weak solutions, characterization of parabolic smoothing effects (implying under proper condition eventual boundedness of trajectories), and convergence of each solution to a (single) equilibrium. In particular, to prove the convergence result, a variant of the so-called ?ojasiewicz–Simon inequality is provided for the fractional Dirichlet Laplacian and (possibly) non-analytic (but ) nonlinearities. 相似文献
40.
We give a sheaf theoretic interpretation of Potts models with external magnetic field, in terms of constructible sheaves and their Euler characteristics. We show that the polynomial countability question for the hypersurfaces defined by the vanishing of the partition function is affected by changes in the magnetic field: elementary examples suffice to see non-polynomially countable cases that become polynomially countable after a perturbation of the magnetic field. The same recursive formula for the Grothendieck classes, under edge-doubling operations, holds as in the case without magnetic field, but the closed formulae for specific examples like banana graphs differ in the presence of magnetic field. We give examples of computation of the Euler characteristic with compact support, for the set of real zeros, and find a similar exponential growth with the size of the graph. This can be viewed as a measure of topological and algorithmic complexity. We also consider the computational complexity question for evaluations of the polynomial, and show both tractable and NP-hard examples, using dynamic programming. 相似文献