全文获取类型
收费全文 | 1436篇 |
免费 | 33篇 |
国内免费 | 9篇 |
专业分类
化学 | 927篇 |
晶体学 | 17篇 |
力学 | 73篇 |
数学 | 205篇 |
物理学 | 256篇 |
出版年
2023年 | 7篇 |
2022年 | 25篇 |
2021年 | 28篇 |
2020年 | 28篇 |
2019年 | 28篇 |
2018年 | 31篇 |
2017年 | 25篇 |
2016年 | 34篇 |
2015年 | 42篇 |
2014年 | 50篇 |
2013年 | 79篇 |
2012年 | 101篇 |
2011年 | 94篇 |
2010年 | 58篇 |
2009年 | 62篇 |
2008年 | 92篇 |
2007年 | 97篇 |
2006年 | 69篇 |
2005年 | 74篇 |
2004年 | 50篇 |
2003年 | 37篇 |
2002年 | 56篇 |
2001年 | 23篇 |
2000年 | 31篇 |
1999年 | 21篇 |
1998年 | 13篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 13篇 |
1994年 | 18篇 |
1993年 | 16篇 |
1991年 | 9篇 |
1990年 | 14篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 8篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1976年 | 6篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1942年 | 4篇 |
1937年 | 4篇 |
1926年 | 3篇 |
排序方式: 共有1478条查询结果,搜索用时 15 毫秒
1.
2.
Francesco Segatta David M. Rogers Naomi T. Dyer Ellen E. Guest Zhuo Li Hainam Do Artur Nenov Marco Garavelli Jonathan D. Hirst 《Molecules (Basel, Switzerland)》2021,26(2)
A fully quantitative theory of the relationship between protein conformation and optical spectroscopy would facilitate deeper insights into biophysical and simulation studies of protein dynamics and folding. In contrast to intense bands in the far-ultraviolet, near-UV bands are much weaker and have been challenging to compute theoretically. We report some advances in the accuracy of calculations in the near-UV, which were realised through the consideration of the vibrational structure of the electronic transitions of aromatic side chains. 相似文献
3.
E. C. Ferreira J. A. P. da Costa J. A. K. Freire G. A. Farias V. N. Freire 《Applied Surface Science》2002,190(1-4):191-194
Confined excitons in non-abrupt GaAs/AlxGa1−xAs single quantum wells are studied. The graded interfaces are described taking into account fluctuations in their thickness a and positioning with respect to the abrupt interface picture. Numerical results for confined (0,0),(1,1) and (0,2) excitons in GaAs/Al0.3Ga0.7As quantum wells show that while the interfacial fluctuations produce small changes (<0.5 meV) in the exciton binding energies, the confined exciton energies can be red- or blue-shifted as much as 25 meV for wells with mean width of 50 Å and 2 ML wide interfaces. 相似文献
4.
F. F. Maia Jr. J. A. K. Freire G. A. Farias V. N. Freire E. F. da Silva Jr. 《Applied Surface Science》2002,190(1-4):247-251
The excitonic properties of a ZnSe/ZnSxSe1−x strained quantum well (QW) are calculated taking into account interface effects. Numerical results obtained with ZnS0.18Se0.82/ZnSe QWs show that graded interfaces can be responsible for a strong broadening of excitonic spectra. 相似文献
5.
Affine Arithmetic: Concepts and Applications 总被引:2,自引:0,他引:2
Affine arithmetic is a model for self-validated numerical computation that keeps track of first-order correlations between computed and input quantities. We explain the main concepts in affine arithmetic and how it handles the dependency problem in standard interval arithmetic. We also describe some of its applications. 相似文献
6.
Emily S. Tepe Ellen S. Deutsch MD Quiana Sampson Stephen Lawless James S. Reilly Robert Thayer Sataloff 《Journal of voice》2002,16(2):244-250
The objective of this study was to determine the incidence of vocal problems in young choir singers and to correlate vocal problems with demographic and behavioral information. A questionnaire addressing vocal habits and hygiene was offered to 571 young choir singers, up to 25 years of age, who sing at least weekly; 129 (22.6%) responded. More than one-half of the respondents had experienced vocal difficulty, particularly older adolescents. Detrimental behaviors and circumstances surveyed were not reflective of the incidence of vocal difficulty, except for morning hoarseness, chronic fatigue, insomnia, and female gender after puberty. Voice care professionals should be aware that self-reported voice difficulties are common among young choral singers, especially postpubescent girls, and children with symptoms consistent with reflux (morning hoarseness) and emotional stress (insomnia). Laryngologists should communicate with choral conductors and singing teachers to enhance early identification and treatment of children with voice complaints, and to develop choral educational strategies that help decrease their incidence. 相似文献
7.
We investigate the dependence of the relaxation time of the current flowing in a nematic cell submitted to an external dc voltage on the physical properties of the substrate. We show that previously presented analyses of the same problem are not very useful for practical applications. We compare our theoretical predictions with experimental data, and show that the agreement is rather good. The influence of the adsorption-desorption phenomenon on the relaxation time is also discussed. 相似文献
8.
A control volume type numerical methodology for the analysis of steady three‐dimensional rotating flows with heat transfer, in both laminar and turbulent conditions, is implemented and experimentally tested. Non‐axisymmetric momentum and heat transfer phenomena are allowed for. Turbulent transport is alternatively represented through three existing versions of the k–ε model that were adjusted to take into account the turbulence anisotropy promoted by rotation, streamline curvature and thermal buoyancy. Their relative performance is evaluated by comparison of calculated local and global heat balances with those obtained through measurements in a laboratory device. A modified version of the Lam and Bremhorst, low Reynolds number model is seen to give the best results. A preliminary analysis focused on the flow structure and the transfer of heat is reported. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
9.
High resolution synchrotron X-ray measurements have been performed on the uniaxial and biaxial phases of the lyotropic mixture potassuim laurate, decanol and water. An elegant magnetic orientational procedure allows us to obtain the cut of the reciprocal space image of the biaxial phase at the plane perpendicular to the amphiphilic bilayer. The analysis of densitometric profiles of the diffracted bands indicate an anisotropic micellar correlation in the plane of the amphiphilic bilayer. It is suggested that an anisotropic distribution of decanol and potassium laurate in this plane could be responsible for this effect. 相似文献
10.
Margaret S. Cheney und Ellen Swallow Richards 《Fresenius' Journal of Analytical Chemistry》1878,17(1):214-216
Ohne Zusammenfassung 相似文献