全文获取类型
收费全文 | 532篇 |
免费 | 6篇 |
专业分类
化学 | 288篇 |
力学 | 16篇 |
数学 | 45篇 |
物理学 | 189篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 3篇 |
2013年 | 32篇 |
2012年 | 20篇 |
2011年 | 25篇 |
2010年 | 22篇 |
2009年 | 14篇 |
2008年 | 19篇 |
2007年 | 27篇 |
2006年 | 16篇 |
2005年 | 13篇 |
2004年 | 18篇 |
2003年 | 20篇 |
2002年 | 17篇 |
2001年 | 11篇 |
2000年 | 16篇 |
1999年 | 18篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 16篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1974年 | 3篇 |
1973年 | 8篇 |
1904年 | 2篇 |
1878年 | 2篇 |
排序方式: 共有538条查询结果,搜索用时 15 毫秒
71.
Don N. Page 《Physics letters. [Part B]》1979,85(4):369-372
The Green's functions for scalar fields propagating on the self-dual gravitational multi-instantons and multi-Taub-NUT metrics are given explicitly in closed form. The special cases for flat space, Taub-NUT and the Eguchi-Hanson instanton are listed. A construction is described for obtaining the Green's functions for fields of arbitrary spin. 相似文献
72.
William A. Page Ralph E. Sutton Robert J. Miller 《Journal of Quantitative Spectroscopy & Radiative Transfer》1973,13(12):1343-1364
A computer program is developed which predicts the vertical distribution of an absorbing species in an isotropically-scattering, finite planetary atmosphere from measurements of the upwelling band radiance determined by a vertically traversing 2-channel radiometer. Comparison is made with experiment. 相似文献
73.
The structure of low quartz has been refined at 94, 115, 150, 190, 240 and 298K using Mo Kα intensities up to 2θ = 90° with residuals around 1.25%. The major structural change from 94 to 298K is an increase of the SiOSi angle from 142.69(4) to 143.65(5) corresponding to a rotation by ~0.8° of a rigid SiO4 tetrahedron around the crystallographic 2-axis through its central Si. The orientations of the principal axes of vibration of Si and O do not change significantly with temperature. The temperature dependence of the mean-square displacement of O along its principal axes follows the Debye formula of thermal motion quite well, while for Si the experimental slopes are significantly less than their calculated values. 相似文献
74.
A. G. Wikjord D. H. Page R. St. John Manley 《Journal of Macromolecular Science: Physics》2013,52(2):413-436
Macroscopic particles of various morphological forms are created by the crystallization of isotactic polystyrene from rapidly stirred solutions. Crystallization from trimethylbenzene over a 150° C temperature range produced spherical particles, globules, fibers, and rings depending upon the growth temperature. Crystallization from cyclohexanol (θ = 83.5°C) produced fibers in the temperature range of 85° to 140° C. Globular structures, similar to those formed by stirrer crystallization in trimethylbenzene developed during the Ziegler-Natta polymerization of styrene in trimethylbenzene between 25° and 75°C. Highly birefringent conical appendages appeared on many of the globules and fibers. The fibers often exhibited a skin-core effect with an average longitudinal and transverse orientation of the chain molecules in the skin and core, respectively. The skin frequently displayed periodic banded extinctions. All of these macrostructures consisted of a highly porous assembly of constituent microfibrillar units. It is believed that the morphogenesis of these structures involves the gradual aggregation of microfibrils under the influence of the flow patterns of the system. 相似文献
75.
Abstract A Monte Carlo code is described which simulates angle resolved Auger electron energy spectra from highly charged ion surface interaction. The combined effect of the Doppler spread of laboratory emission energy and electron scattering by the solid, together with the broad inherent line width, is found to have considerable influence on the spectral lines. As a new feature, low or high energy shoulders can appear. By comparison between simulated and measured spectra information on the kinematic and electronic state of the projectile ions in the moment of electron emission can be extracted. The standard method of spectrum analysis, which is based on the assumption of direct escape of the electrons, is evaluated with respect to the simulated spectra. 相似文献
76.
77.
78.
79.
Miles G. Page Dr. Thomas Zemb Prof. Monique Dubois Dr. Helmut Cölfen Dr. 《Chemphyschem》2008,9(6):882-890
We show that analytical ultracentrifugation can be applied to derive full equations of state of colloids in a single sedimentation equilibrium experiment, by determination of single‐phase boundaries as well as of osmotic pressure versus concentration at fixed temperatures. A continuous dependence of the osmotic pressure, over orders of magnitude between at least ~101 and 104 Pa, and a wide concentration range, are determined in agreement with standard theoretical considerations. Two model experimental colloidal systems are investigated: For a well‐known synthetic clay system (laponite), it is shown that two regimes—counter‐ion ideal gas and interacting double layers—can easily be identified in the equation of state, whereas metastable glass‐ or microphase‐separated gel states previously encountered in osmotic stress measurements of laponite are circumvented. For the case of rigid, crystallized catanionic bilayers, single phase domains can be identified. Osmotic pressure results in this case disagree with results obtained using the classical osmotic stress technique, as a result of sample adhesion to the ultracentrifuge cell windows and uncertainty due to possible micromolar ion contamination. 相似文献
80.
A. Norrie Pearce Michael V. Berridge Michael J. Page Victoria L. Webb 《Tetrahedron》2008,64(24):5748-5755
In addition to the known dihydroxystyrylguanidine alkaloid tubastrine (1), five new dimers, orthidines A-E (2-6) and the biosynthetically unrelated 1,14-sperminedihomovanillamide (orthidine F, 7) were isolated from the New Zealand ascidian Aplidium orthium. The structures of the new compounds, elucidated by interpretation of spectroscopic data, encompass benzodioxane neolignan-type scaffolds (2-5) and a 1,2,3,4-tetrasubstituted cyclobutane (6), the latter likely having arisen via [π2s+π2s] dimerization of tubastrine. The subunit head-to-tail orientation of dimer 6 was established unambiguously by interpretation of data from a 2J,3J-HMBC NMR experiment. The structure of 7 was also confirmed by facile synthesis. Compounds 1-4, 6, and 7 inhibited the in vitro production of superoxide by PMA-stimulated human neutrophils in a dose-dependent manner with IC50s of 10-36 μM and this was associated with inhibition of superoxide production by neutrophils in vivo in a murine model of gouty inflammation. 相似文献