全文获取类型
收费全文 | 901篇 |
免费 | 65篇 |
国内免费 | 53篇 |
专业分类
化学 | 298篇 |
晶体学 | 14篇 |
力学 | 5篇 |
综合类 | 4篇 |
数学 | 234篇 |
物理学 | 464篇 |
出版年
2024年 | 5篇 |
2023年 | 7篇 |
2022年 | 13篇 |
2021年 | 11篇 |
2020年 | 18篇 |
2019年 | 13篇 |
2018年 | 17篇 |
2017年 | 31篇 |
2016年 | 29篇 |
2015年 | 24篇 |
2014年 | 32篇 |
2013年 | 244篇 |
2012年 | 19篇 |
2011年 | 25篇 |
2010年 | 28篇 |
2009年 | 28篇 |
2008年 | 19篇 |
2007年 | 9篇 |
2006年 | 27篇 |
2005年 | 45篇 |
2004年 | 43篇 |
2003年 | 27篇 |
2002年 | 34篇 |
2001年 | 29篇 |
2000年 | 23篇 |
1999年 | 16篇 |
1998年 | 27篇 |
1997年 | 16篇 |
1996年 | 22篇 |
1995年 | 15篇 |
1994年 | 14篇 |
1993年 | 14篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 10篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 4篇 |
排序方式: 共有1019条查询结果,搜索用时 15 毫秒
81.
An Accurate Characterization of CRT Monitor (I) Verifications of Past Studies and Clarifications of Gamma 总被引:1,自引:0,他引:1
CRT monitors are widely used to view images on the Internet. The color images on the computer graphic display can be printed out or displayed on other monitors through the Internet, and color matching between the original and the reproduction is very important. The color management systems (CMSs) are useful for the color matching. CMSs utilize device profiles, in which color characteristic information is stored, and these profiles are generated by device characterization. Thus, an accurate characterization of the monitor is essential for better color matching. CRT monitor characteristics can be described by the tone reproduction curves (TRCs) of each channel, and color additive matrix. In this paper, these characteristics were investigated from a physical point of view. Various kinds of flare and the interdependence among the channels were also investigated and verified. The definition of the term “gamma” is clarified, which is very often used to describe the TRC. Various definitions are compared and a new definition of S-γ is proposed. 相似文献
82.
83.
R. Wadsworth I. RagnarssonB.G. Carlsson Hai-Liang Ma P.J. DaviesC. Andreoiu R.A.E. Austin M.P. CarpenterD. Dashdorj S.J. Freeman P.E. Garrett J. GreeneA. Görgen D.G. JenkinsF. Johnston-Theasby P. JoshiA.O. Macchiavelli F. MooreG. Mukherjee W. ReviolD.G. Sarantites D. SeweryniakC.E. Svensson J.J. Valiente-Dobón 《Physics letters. [Part B]》2011,701(3):306-312
Four previously known rotational bands in 76Rb have been extended to moderate spins using the Gammasphere and Microball γ ray and charged particle detector arrays and the 40Ca(40Ca, 3pn) reaction at a beam energy of 165 MeV. The properties of two of the negative-parity bands can only readily be interpreted in terms of the highly successful Cranked Nilsson-Strutinsky model calculations if they have the same configuration in terms of the number of g9/2 particles, but they result from different nuclear shapes (one near-oblate and the other near-prolate). These data appear to constitute a unique example of shape coexisting structures at medium spins. 相似文献
85.
Blend films of different ratios of carboxymethyl cellulose (CMC)/polyethylene oxide (PEO) were prepared by the solution casting method. To investigate the effect of irradiation on all properties of prepared blend, it was exposed to different gamma irradiation doses (10, 20, and 30?kGy). Physical properties such as gel fraction (GF) (%) and swelling (SW) (%) were investigated. It was found that the GF (%) increases with increasing irradiation dose up to 20?kGy, while SW (%) decreases with an increase in the irradiation doses for all blend compositions. Moreover, the structural and mechanical properties of the prepared films were studied. The results of the mechanical properties obtained showed that there is an improvement in these properties with an increase in both CMC and irradiation dose up to 20?kGy. The efficiency of metal ions uptake was measured using a UV spectrophotometer. The prepared films showed good tendency to absorb and release metal ions from aqueous media. Thus, the CMC/PEO film can be used in agricultural domain. 相似文献
86.
J. Šulc 《Isotopes in environmental and health studies》2013,49(7):254-256
On the basis of a simplified mathematical model there is calculated the probability of a photon of characteristic K series radiation excited by a photon of low energy gamma radiation hitting the detector. There are also included the probabilities for coherently and incoherently scattered primary radiation considering electron binding energies. 相似文献
87.
This paper deals with the direct measurement of total (fixed plus removable) surface activity in the presence of interfering radiation fields. Two methods based on Monte Carlo simulations are used: one for a Geiger–Muller (GM) ionisation probe and the other for sodium iodide (NaI) detector with lead collimators; equations for the most general case and the geometry models for Monte Carlo simulation of both (GM and NaI) detectors are employed. Finally, an example of application is discussed. 相似文献
88.
We consider the problem of discriminating between two independent multivariate normal populations, Np(μ1, Σ1) and Np(μ2, Σ2), having distinct mean vectors μ1 and μ2 and distinct covariance matrices Σ1 and Σ2. The parameters μ1, μ2, Σ1, and Σ2 are unknown and are estimated by means of independent random training samples from each population. We derive a stochastic representation for the exact distribution of the “plug-in” quadratic discriminant function for classifying a new observation between the two populations. The stochastic representation involves only the classical standard normal, chi-square, and F distributions and is easily implemented for simulation purposes. Using Monte Carlo simulation of the stochastic representation we provide applications to the estimation of misclassification probabilities for the well-known iris data studied by Fisher (Ann. Eugen.7 (1936), 179–188); a data set on corporate financial ratios provided by Johnson and Wichern (Applied Multivariate Statistical Analysis, 4th ed., Prentice–Hall, Englewood Cliffs, NJ, 1998); and a data set analyzed by Reaven and Miller (Diabetologia16 (1979), 17–24) in a classification of diabetic status. 相似文献
89.
Tetsuya Momotani 《Proceedings of the American Mathematical Society》2006,134(9):2541-2548
As a generalization of recent work by Kurokawa, Matsuda, and Wakayama (2004) we introduce a higher Riemann zeta function for an abstract sequence. Then we explicitly determine its regularized product expression.
90.
J. J. Carroll J. Burnett T. Drummond J. Lepak R. Propri D. Smith S. A. Karamian J. Adam F. Stedile F. J. Agee 《Hyperfine Interactions》2002,143(1-4):37-54
Experiments with the long-lived, high-K isomer 178Hfm2 have been recognized as intriguing tests of multi-quasiparticle state structures and their interactions with external radiation.
A triggered release of the energy stored by this isomer, 2.5 MeV per nucleus or 1.2 GJ/gram, in the form of a gamma-ray burst
might prove valuable for numerous applications. The observation of “accelerated” decay of 178Hfm2 during irradiation by 90-keV bremsstrahlung has already been reported, but with poor statistical accuracy due to the experimental
approach. That approach employed single Ge detectors to seek increases in the areas of peaks at energies corresponding to
transitions in the spontaneous decay of the isomer. The need for better quality data to confirm those results has motivated
the development of improved detection concepts. One such concept was utilized here to perform an initial search for low-energy
(<20 keV) triggered gamma emission from 178Hfm2 using the YSU miniball detector array.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献