全文获取类型
收费全文 | 7638篇 |
免费 | 850篇 |
国内免费 | 679篇 |
专业分类
化学 | 2632篇 |
晶体学 | 79篇 |
力学 | 2520篇 |
综合类 | 81篇 |
数学 | 705篇 |
物理学 | 3150篇 |
出版年
2024年 | 6篇 |
2023年 | 56篇 |
2022年 | 107篇 |
2021年 | 149篇 |
2020年 | 250篇 |
2019年 | 167篇 |
2018年 | 207篇 |
2017年 | 241篇 |
2016年 | 310篇 |
2015年 | 272篇 |
2014年 | 413篇 |
2013年 | 572篇 |
2012年 | 340篇 |
2011年 | 470篇 |
2010年 | 391篇 |
2009年 | 474篇 |
2008年 | 448篇 |
2007年 | 521篇 |
2006年 | 468篇 |
2005年 | 400篇 |
2004年 | 451篇 |
2003年 | 352篇 |
2002年 | 314篇 |
2001年 | 250篇 |
2000年 | 244篇 |
1999年 | 232篇 |
1998年 | 169篇 |
1997年 | 138篇 |
1996年 | 119篇 |
1995年 | 103篇 |
1994年 | 81篇 |
1993年 | 63篇 |
1992年 | 63篇 |
1991年 | 80篇 |
1990年 | 37篇 |
1989年 | 23篇 |
1988年 | 29篇 |
1987年 | 25篇 |
1986年 | 19篇 |
1985年 | 18篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 11篇 |
1979年 | 16篇 |
1977年 | 5篇 |
1973年 | 5篇 |
1971年 | 4篇 |
1957年 | 6篇 |
排序方式: 共有9167条查询结果,搜索用时 31 毫秒
101.
102.
We report on first experiments combining quasi-digital highly selective etching and atomic force microscopy (AFM) to examine the interior interfaces of semiconductor heterostructures. Lattice matched (GaIn)As/InP heterostructures grown by metalorganic vapour-phase epitaxy (MOVPE) are taken as a model system to check the capabilities of this new method. Standard selective etchants for different material systems have been optimized in selectivity and etch rate to achieve a quasi-digital etching behaviour. In this way, the real structure of interior interfaces can be determined by AFM. We find a significant difference between the surface of the heterostructure and the interior interfaces. 相似文献
103.
We apply the least‐squares finite element method with adaptive grid to nonlinear time‐dependent PDEs with shocks. The least‐squares finite element method is also used in applying the deformation method to generate the adaptive moving grids. The effectiveness of this method is demonstrated by solving a Burgers' equation with shocks. Computational results on uniform grids and adaptive grids are compared for the purpose of evaluation. The results show that the adaptive grids can capture the shock more sharply with significantly less computational time. For moving shock, the adaptive grid moves correctly with the shock. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006 相似文献
104.
根据对应原理,得到了类氢原子能态平均寿命半经典的计算公式τ(n,l),然后利用相对论单通道量子数亏损理论进行推广,得到用来计算考虑总角动量J的激发态寿命公式τ(n,l,l+1/2)和τ(n,l,l-1/2),利用单通道量子数亏损理论得到了碱金属原子n、l远大于1时激发态寿命的半经典公式τ(n.l)=τ0(m+M/nm/v/+M)2v7l(l+1/2)/n4,其计算结果和实验数据符合的很好. 相似文献
105.
Atsushi Yamagami 《Journal of Number Theory》2003,99(1):120-138
In this article, for a residual modular representation defined over an arbitrary finite field, Gouvêa's conjecture which says that the universal deformation ring is isomorphic to a certain Hecke algebra is proven in the unobstructed case. 相似文献
106.
Maxim Braverman Valentin Silantyev 《Transactions of the American Mathematical Society》2006,358(8):3329-3361
We extend the Novikov Morse-type inequalities for closed 1-forms in 2 directions. First, we consider manifolds with boundary. Second, we allow a very degenerate structure of the critical set of the form, assuming only that the form is non-degenerated in the sense of Kirwan. In particular, we obtain a generalization of a result of Floer about the usual Morse inequalities on a manifold with boundary. We also obtain an equivariant version of our inequalities.
Our proof is based on an application of the Witten deformation technique. The main novelty here is that we consider the neighborhood of the critical set as a manifold with a cylindrical end. This leads to a considerable simplification of the local analysis. In particular, we obtain a new analytic proof of the Morse-Bott inequalities on a closed manifold.
107.
Ken‐ichi Shinohara Tasuku Suzuki Takeshi Kitami Shingo Yamaguchi 《Journal of polymer science. Part A, Polymer chemistry》2006,44(2):801-809
We fabricated a micrometer‐long supramolecular chain in which π‐conjugated polyrotaxane was coupled. A new experimental setup was designed and constructed, and the simultaneous direct imaging of the structure and fluorescent function was achieved. Furthermore, we identified the formation of a polymer intertwined network and observed novel fluorescence due to a long‐range interaction via this intertwined network over a distance of 5 μm or more without quenching over 15 min in the near field. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 801–809, 2006 相似文献
108.
Wolfgang H. Binder Laura Petraru Robert Sachenshofer Ronald Zirbs 《Monatshefte für Chemie / Chemical Monthly》2006,137(7):835-841
Summary. The surface modification of nanoparticles via azide/alkine-1,3-dipolar cycloaddition-reactions is described. Ligand exchange onto various nanoparticles was monitored by
1H NMR spectroscopy and formed the basis for the attachment of ligands onto the nanoparticles and their subsequent modification
by dipolar cycloaddition reactions. Nanoparticle-surfaces were monitored by binding onto self-assembled monolayers derivatized
with matching supramolecular interactions after derivatization. 相似文献
109.
用力敏传感器测量液体表面张力系数 总被引:17,自引:3,他引:14
利用力敏传感器测量液体表面张力系数,既改进了传统的实验方法和仪器,提高了实验的准确度和稳定性,同时因实现了非电量电测,也有助于测量过程中学生对物理过程的观察和规律的理解。 相似文献
110.
We define nontempered (exponential growth) function spaces on the Lie group ax+b which are stable under some left-invariant (convergent) star product. The techniques used to achieved the latter come from symmetric spaces geometry and star representation theory. 相似文献