全文获取类型
收费全文 | 464篇 |
免费 | 12篇 |
国内免费 | 14篇 |
专业分类
化学 | 81篇 |
晶体学 | 2篇 |
力学 | 5篇 |
综合类 | 1篇 |
数学 | 34篇 |
物理学 | 59篇 |
综合类 | 308篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 8篇 |
2015年 | 11篇 |
2014年 | 20篇 |
2013年 | 15篇 |
2012年 | 33篇 |
2011年 | 35篇 |
2010年 | 41篇 |
2009年 | 27篇 |
2008年 | 40篇 |
2007年 | 44篇 |
2006年 | 23篇 |
2005年 | 22篇 |
2004年 | 31篇 |
2003年 | 18篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1968年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有490条查询结果,搜索用时 31 毫秒
471.
LI Yu-Lan CAO Liang-Jun QI Hui-Rong LI Jin KANG Ke-Jun LI Yuan-Jing LAI Yong-Fang GAO Yuan-Ning YANG Zhen-Wei 《中国物理C(英文版)》2008,32(1)
A time projection chamber (TPC) readout by gas electron multipliers (GEM) detector is a very promising candidate for the central tracking system of ILC (International Linear Collider). A prototype is designed and set up in our lab and introduced here. The tests during and after the assembly prove that the prototype TPC has been constructed successfully. It is ready for further study. 相似文献
472.
T. Yoshioka 《Pramana》2007,69(6):1115-1118
Most of the important physics processes to be studied in the international linear collider (ILC) experiment have multi-jets
in the final state. In order to achieve better jet energy resolution, the so-called particle flow algorithm (PFA) will be
employed and there is a general consensus that PFA derives overall ILC detector design. Four detector concepts for the ILC
experiment have been proposed so far in the world; the GLD detector that has a large inner calorimeter radius, which is considered
to have an advantage for a PFA, is one of them. In this paper, general scheme and performance of the GLD-PFA will be presented.
相似文献
473.
John Hauptman 《Pramana》2007,69(6):1037-1046
The 4th concept detector consists of four detector subsystems, a small-pixel vertex detector, a high-resolution TPC, a new
multiple-readout fiber calorimeter and a new dual-solenoid iron-free muon system. We discuss the design of a comprehensive
facility that measures and identifies all partons of the standard model, including hadronic W → jj and Z → jj decays, with high precision and high efficiency. We emphasis here the calorimeter and muon systems.
相似文献
474.
中国高技术产业发展促进会知识产权战略研究课题组 《科技促进发展》2014,10(1):118-122
英国自称世界第二大科技强国。但是,其伦敦"硅谷"的知识产权治理模式、政府治理模式已透露出落后的一面,成为"知识产权制度创新"的不毛之地。伦敦城公司治理模式则具有更强的实用性,美国硅谷研究会称其是知识产权密集产业"最有吸引力"的社会治理模式,并呼吁美国硅谷各自治体积极引进这种传统治理模式。本文认为在知识经济时代,通过法人权利的全面宪法化,逐步振兴企业商会的分散式、契约式知识产权治理,将是一个伟大的法治进程。 相似文献
475.
Brenda P. Winnewisser 《Journal of Molecular Spectroscopy》2011,269(1):2-11
A history of the OSU International Symposium on Molecular Spectroscopy is presented with a broad brush, inspired by looking at the evolution of the program booklets of the meeting, and drawing upon a selection of abstracts, all of which are now accessible on-line, and on reminiscences. The important and enduring aspects of the meeting from the perspective of the author are identified, and a few of the changes traced. The essential contributions of the founders and successive official hosts of the meeting, Harald H. Nielsen, David Dennison, K. Narahari Rao, and Terry A. Miller are acknowledged. 相似文献
476.
This study investigates the presence of deterministic dependencies in international stock markets using recurrence plots and recurrence quantification analysis (RQA). The results are based on a large set of free float-adjusted market capitalization stock indices, covering a period of 15 years. The statistical tests suggest that the dynamics of stock prices in emerging markets is characterized by higher values of RQA measures when compared to their developed counterparts. The behavior of stock markets during critical financial events, such as the burst of the technology bubble, the Asian currency crisis, and the recent subprime mortgage crisis, is analyzed by performing RQA in sliding windows. It is shown that during these events stock markets exhibit a distinctive behavior that is characterized by temporary decreases in the fraction of recurrence points contained in diagonal and vertical structures. 相似文献
477.
Bank productivity and performance groups: A decomposition approach based upon the Luenberger productivity indicator 总被引:2,自引:0,他引:2
Mircea Epure 《European Journal of Operational Research》2011,211(3):630-641
The purpose of this paper is twofold. First, in the framework of the strategic groups’ literature, it analyZes changes in productivity and efficiency of Spanish private and savings banks over an eight-year period (1998-2006). Second, by adapting the decomposition of the Malmquist productivity indices suggested by Färe et al. (1994), it proposes similar components decomposing the Luenberger productivity indicator. Initially, productivity is decomposed into technological and efficiency changes. Thereafter, this efficiency change is decomposed into pure efficiency, scale and congestion changes. Empirical results demonstrate that productivity improvements are partially due to technological innovation. Furthermore, it is shown how the competition between private and savings banks develops in terms of the analyzed productivity and efficiency components. While private banks enjoy better efficiency change, savings banks contribute more to technological progress. Consequently, the Luenberger components are used as cluster analysis inputs. Thus, economic interpretations of the resulting performance groups are made via key differences in productivity components. Finally, following the strategic groups’ literature, supplementary insights are gained by linking these performance groups with banking ratios. 相似文献
478.
The entropy optimization approach has widely been applied in finance for a long time, notably in the areas of market simulation, risk measurement, and financial asset pricing. In this paper, we propose copula entropy models with two and three variables to measure dependence in stock markets, which extend the copula theory and are based on Jaynes’s information criterion. Both of them are usually applied under the non-Gaussian distribution assumption. Comparing with the linear correlation coefficient and the mutual information, the strengths and advantages of the copula entropy approach are revealed and confirmed. We also propose an algorithm for the copula entropy approach to obtain the numerical results. With the experimental data analysis at the country level and the economic circle theory in international economy, the validity of the proposed approach is approved; evidently, it captures the non-linear correlation, multi-dimensional correlation, and correlation comparisons without common variables. We would like to make it clear that correlation illustrates dependence, but dependence is not synonymous with correlation. Copulas can capture some special types of dependence, such as tail dependence and asymmetric dependence, which other conventional probability distributions, such as the normal p.d.f. and the Student’s t p.d.f., cannot. 相似文献
479.
Permanent need to understand nature, structure and properties of humic substances influences also separation methods that are in a wide scope used for fractionation, characterization and analysis of humic substances (HS). At the first glance techniques based on size-exclusion phenomena are the most useful and utilized for relating elution data to the molecular mass distribution of HS, however, with some limitations and exceptions, respectively, in the structural investigation of HS. The second most abundant separation mechanism is reversed-phase based on weak hydrophobic interactions beneficially combined with the step gradients inducing distinct features in rather featureless analytical signal of HS. Relatively great effort is invested to the developments of immobilized-metal affinity chromatography mimicking chelate-forming properties of HS as ligands in the environment. Surprisingly, relatively less attention is given to the ion-ion interactions based ion-exchange chromatography of HS. Chromatographic separation methods play also an important role in the examination of interactions of HS with pesticides. They allow us to determine binding constants and the other data necessary to predict the mobility of chemical pollutants in the environment. HS is frequently adversely acting in analytical procedures as interfering substance, so more detailed information is desired on manifestation of its numerous properties in analytical procedures. The article topic is covered by the review emphasizing advances in the field done in the period of last 10 years from 2000 till 2010. 相似文献
480.
The problems of ITRF2008,the latest International Terrestrial Reference Frame,are pointed out and analyzed as follows:(1) ITRF is not a mm-level Terrestrial Reference Frame;(2) the origin of ITRF is neither the Earth's center of mass (CM) nor the center of figure (CF);(3) the scale of ITRF is not a uniform system in the sense of the gravitational theory of relativity.These problems result from the linear hypothesis used in the establishment and maintenance of ITRF,which includes the linear hypothesis of the... 相似文献