全文获取类型
收费全文 | 200篇 |
免费 | 5篇 |
国内免费 | 16篇 |
专业分类
化学 | 42篇 |
力学 | 6篇 |
综合类 | 2篇 |
数学 | 139篇 |
物理学 | 32篇 |
出版年
2023年 | 8篇 |
2022年 | 4篇 |
2021年 | 2篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 21篇 |
2012年 | 10篇 |
2011年 | 18篇 |
2010年 | 14篇 |
2009年 | 13篇 |
2008年 | 12篇 |
2007年 | 17篇 |
2006年 | 6篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有221条查询结果,搜索用时 312 毫秒
61.
62.
Exotic electronic excitations beyond normal selection rules would open novel possibilities for photoenergy conversion. The large intensity gradient of electromagnetic fields resulting from the confinement of localized surface plasmons at the molecular scale could exceed the limit of light–matter interactions via modification of electronic excitation selection rules. We discuss the possible application of surface-enhanced Raman scattering as a probe for exotic electronic excitations by reviewing studies on small numbers of molecules at the surface of plasmonic metal nanostructures. Future innovative photo-functionalization is also discussed by considering the excited states produced by the exotic electronic excitations. 相似文献
63.
We study existence and stability of stationary solutions of a system of semilinear parabolic partial differential equations that occurs in population genetics. It describes the evolution of gamete frequencies in a geographically structured population of migrating individuals in a bounded habitat. Fitness of individuals is determined additively by two recombining, diallelic genetic loci that are subject to spatially varying selection. Migration is modeled by diffusion. Of most interest are spatially non-constant stationary solutions, so-called clines. In a two-locus cline all four gametes are present in the population, i.e., it is an internal stationary solution. We provide conditions for existence and linear stability of a two-locus cline if recombination is either sufficiently weak or sufficiently strong relative to selection and diffusion. For strong recombination, we also prove uniqueness and global asymptotic stability. For arbitrary recombination, we determine the stability properties of the monomorphic equilibria, which represent fixation of a single gamete. 相似文献
64.
We propose a type-dependent branching model with mutation and competition for modelling phylogenies of a virus population. The competition kernel depends on the total mass, the types of the virus particles, and the genetic information available through the number of nucleotide substitutions separating the virus particles. We consider evolving phylogenies in the huge population, short reproduction time and frequent mutation regime, show tightness in the space of marked metric measure spaces and characterize the limit through a martingale problem. Due to heterogeneity in the branching rates, the phylogenies are not ultra-metric. We therefore develop new techniques for verifying compact containment. 相似文献
65.
随着中央关于“职业院校制造业和现代服务业技能型紧缺性人才培养培训工程”的政策出台,以及“2004年全国首届数控技能大赛”的成功举办,使得职业学校的数控专业建设逐步发展并完善起来,各种形式的数控技能竞赛也如火如荼地开展起来。本文从参加数控技能比赛学生的选拔和培训两个方面做了简单的介绍. 相似文献
66.
This article presents a model of insurance and investment risk diversification. An in-depth analysis of the mathematical formulation of the risk is presented. In this regard, we introduce a new concept called the substitution principle to formulate the model rigorously. We show that, if the investment risks are normally non-linear, the insurance risks are linear in nature. This proves that the well-known diversification principle has to be viewed differently in finance and in insurance. 相似文献
67.
《纺织品介电常数测定》实验中样品的选择 总被引:3,自引:0,他引:3
“纺织品介电常数测定”实验中样品的选择对保证实验的顺利进行十分重要。对多种样品在多种条件下进行测试。并对实验结果进行了分析。 相似文献
68.
69.
Jenny Triptow Dr. André Fielicke Prof. Gerard Meijer Dr. Mallory Green 《Angewandte Chemie (International ed. in English)》2023,62(1):e202212020
Photoelectron Circular Dichroism (PECD) is a forward-backward asymmetry in the photoemission from a non-racemic sample induced by circularly polarized light. PECD spectroscopy has potential analytical advantages for chiral discrimination over other chiroptical methods due to its increased sensitivity to the chiral potential of the molecule. The use of anions for PECD spectroscopy allows for mass-selectivity and provides a path to simple experimental schemes that employ table-top light sources. Evidence of PECD for anions is limited, and insight into the forces that govern PECD electron dynamics in photodetachment is absent. Here, we demonstrate a PECD effect in the photodetachment of mass-selected deprotonated 1-indanol anions. By utilizing velocity map imaging photoelectron spectroscopy with a tunable light source, we determine the energy-resolved PECD over a wide range of photon energies. The observed PECD reaches up to 11 %, similar to what has been measured for neutral species. 相似文献
70.