全文获取类型
收费全文 | 286篇 |
免费 | 10篇 |
国内免费 | 3篇 |
专业分类
化学 | 58篇 |
力学 | 6篇 |
综合类 | 2篇 |
数学 | 79篇 |
物理学 | 154篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 1篇 |
2016年 | 14篇 |
2015年 | 9篇 |
2014年 | 10篇 |
2013年 | 10篇 |
2012年 | 6篇 |
2011年 | 17篇 |
2010年 | 7篇 |
2009年 | 19篇 |
2008年 | 24篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 13篇 |
2004年 | 17篇 |
2003年 | 14篇 |
2002年 | 11篇 |
2001年 | 5篇 |
2000年 | 12篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1978年 | 3篇 |
1959年 | 1篇 |
排序方式: 共有299条查询结果,搜索用时 203 毫秒
131.
Fitzpatrick F Ramaker HJ Schoenmakers P Beerends R Verheggen M Phillipsen H 《Journal of chromatography. A》2004,1043(2):239-248
A perfluorinated co-polyether was characterised in terms of the number and type of functional end groups present on the molecule. The polymer was separated chromatographically according to the polarity of the polymer end groups and the separation was coupled on-line to an electrospray ionisation time-of-flight mass spectrometer. Negative-mode electrospray ionisation of the relatively non-polar polymer was achieved by post-column addition of a polar constituent to the mobile phase. LC-MS analysis of polydisperse analytes is a highly data intensive technique and manual interpretation of the resulting data can be extremely complicated, especially for the characterisation of copolymers or polymers with end-group distributions. In order to overcome this problem, an automated data-analysis program was developed that allows the user to quickly determine the probability of the presence of a certain molecular compound. The program evaluated data in terms of the possible combinations of monomeric units and end groups that could be combined to make up the mass values present in the mass spectra. Using the program, the polymer can be characterised according to its molar-mass, chemical-composition and functionality-type distributions. A graphical representation of the LC-MS analyses is presented to give a clear overview of the two-dimensional separation. The identification of various end groups on the polymer is also presented graphically, as (a) a histogram (frequency of matches versus time), (b) a two-dimensional plot (masses that match the particular end group combination versus LC retention time) and (c) a plot of average chemical composition versus LC retention time. 相似文献
132.
M. V. Korolevich M. R. Zhbankova V. N. Piottukh-Peletskii R. G. Zhbankov 《Journal of Structural Chemistry》2007,48(5):821-830
For the first time the detailed interpretation of the IR spectrum of methyl-β-D-glucopyranoside is presented based on the complete calculation of frequencies of normal vibrations and absolute intensities of IR absorption bands and on their comparison with the corresponding experimental values. The characteristic spectral features of oxymethyl substitution for the hydroxyl group are detected. The regularities in the formation of the complex band structure in a frequency range from 1150 cm?1 to 950 cm?1 is determined. 相似文献
133.
It is very important to calculate the equilibrium magnetic field configuration exactly and to estimate the parameters of the device needed for the equilibrium and stability in the design and operate the low-aspect-ratio tokamak, one of the axis-symmetrical torus devices which is widely used in the research of nuclear fusion using plasma. In the previous researches, there were the theoretical and numerical interpretation methods for the high-aspect-ratio tokamak plasma. But for the low-aspect-ratio tokamak plasma, numerical methods such as the finite element method and iteration method are usually used. In this research, we interpreted and examined the features of magnetohydrodynamic equilibrium of the low-aspect-ratio tokamak plasma in combination with the Green function method and finite element method which has high numerical value accuracy. 相似文献
134.
为解决载人航天器并行测试遥测数据集中判读和关联分析问题,提出一种支持多航天器并行测试的综合显示平台设计方法。对多航天器并行测试方案进行研究,对综合显示平台总体架构进行设计。平台采用插件式程序架构便于功能扩展,采用脚本引擎技术提高平台可配置性,采用MVC设计模式增加页面编辑的可维护性,采用多线程技术和定时器策略实现海量数据的实时显示。平台具备图形页面、列表页面、曲线页面显示功能,可以实现常规数值显示、报警监视及源码、序列显示,同时,支持测试数据本地保存与回放判读。综合显示平台已应用于载人航天器全阶段地面测试和某型号航天器在轨交会对接任务中,应用效果良好。 相似文献
135.
No Heading Conventional relativistic quantum mechanics, based on the Klein-Gordon equation, does not possess a natural probabilistic
interpretation in configuration space. The Bohmian interpretation, in which probabilities play a secondary role, provides
a viable interpretation of relativistic quantum mechanics. We formulate the Bohmian interpretation of many-particle wave functions
in a Lorentz-covariant way. In contrast with the nonrelativistic case, the relativistic Bohmian interpretation may lead to
measurable predictions on particle positions even when the conventional interpretation does not lead to such predictions. 相似文献
136.
No Heading The purpose of this paper is to survey the possible topologies of branching spacetimes and, in particular, to refute the popular
notion in the literature that a branching spacetime requires a non-Hausdorff topology. 相似文献
137.
138.
139.
The quantum formalism is a measurement formalism-a phenomenological formalism describing certain macroscopic regularities. We argue that it can be regarded, and best be understood, as arising from Bohmian mechanics, which is what emerges from Schrödinger's equation for a system of particles when we merely insist that particles means particles. While distinctly non-Newtonian, Bohmian mechanics is a fully deterministic theory of particles in motion, a motion choreographed by the wave function. We find that a Bohmian universe, though deterministic, evolves in such a manner that anappearance of randomness emerges, precisely as described by the quantum formalism and given, for example, by = ¦¦
2. A crucial ingredient in our analysis of the origin of this randomness is the notion of the effective wave function of a subsystem, a notion of interest in its own right and of relevance to any discussion of quantum theory. When the quantum formalism is regarded as arising in this way, the paradoxes and perplexities so often associated with (nonrelativistic) quantum theory simply evaporate.This paper is dedicated to the memory of J. S. Bell. 相似文献
140.