全文获取类型
收费全文 | 1028篇 |
免费 | 12篇 |
国内免费 | 7篇 |
专业分类
化学 | 636篇 |
晶体学 | 11篇 |
力学 | 33篇 |
数学 | 91篇 |
物理学 | 276篇 |
出版年
2021年 | 19篇 |
2020年 | 21篇 |
2019年 | 14篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 18篇 |
2015年 | 8篇 |
2014年 | 10篇 |
2013年 | 46篇 |
2012年 | 40篇 |
2011年 | 48篇 |
2010年 | 20篇 |
2009年 | 26篇 |
2008年 | 38篇 |
2007年 | 42篇 |
2006年 | 48篇 |
2005年 | 41篇 |
2004年 | 34篇 |
2003年 | 39篇 |
2002年 | 21篇 |
2001年 | 19篇 |
2000年 | 32篇 |
1999年 | 15篇 |
1998年 | 20篇 |
1997年 | 21篇 |
1996年 | 15篇 |
1995年 | 12篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 17篇 |
1991年 | 13篇 |
1990年 | 12篇 |
1989年 | 7篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 20篇 |
1985年 | 20篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 10篇 |
1979年 | 15篇 |
1978年 | 6篇 |
1977年 | 22篇 |
1976年 | 9篇 |
1975年 | 14篇 |
1974年 | 9篇 |
1973年 | 10篇 |
1917年 | 7篇 |
排序方式: 共有1047条查询结果,搜索用时 15 毫秒
61.
Yiyuan Han Zhixing Lin Jiajing Zhou Gyeongwon Yun Rui Guo Joseph J. Richardson Frank Caruso 《Angewandte Chemie (International ed. in English)》2020,59(36):15618-15625
Functional materials composed of proteins have attracted much interest owing to the inherent and diverse functionality of proteins. However, establishing general techniques for assembling proteins into nanomaterials is challenging owing to the complex physicochemical nature and potential denaturation of proteins. Here, a simple, versatile strategy is introduced to fabricate functional protein assemblies through the interfacial assembly of proteins and polyphenols (e.g., tannic acid) on various substrates (organic, inorganic, and biological). The dominant interactions (hydrogen‐bonding, hydrophobic, and ionic) between the proteins and tannic acid were elucidated; most proteins undergo multiple noncovalent stabilizing interactions with polyphenols, which can be used to engineer responsiveness into the assemblies. The proteins retain their structure and function within the assemblies, thereby enabling their use in various applications (e.g., catalysis, fluorescence imaging, and cell targeting). 相似文献
62.
63.
Per JensenSteven S. Wesolowski Nicole R. BrinkmannNancy A. Richardson Yukio YamaguchiHenry F. Schaefer III P.R. Bunker 《Journal of Molecular Spectroscopy》2002,211(2):254-261
The potential energy surface and dipole moment surfaces of the ã4A2 electronic state of CH2+ are calculated ab initio using an augmented correlation-consistent polarized valence quadruple-ζ (aug-cc-pVQZ) basis set, with the incorporation of dynamical correlation using the coupled cluster method with single and double excitations and perturbatively connected triple excitations [CCSD(T)]. We use these surfaces in the MORBID program system to calculate rotation and rotation-vibration term values for ã-state CH2+, CD+2, and CHD+ and to simulate the rotation and rotation-vibration absorption spectrum of CH2+ in the ã4A2 electronic state. Our work is motivated by studies of CH2+ that use the Coulomb explosion imaging technique and by the goal of predicting spectra that may be obtained from discharge sources. Although the ã state is the lowest-lying excited state above the X?/Ã ground state pair, it turns out to be relatively high-lying, and we determine that Te(ã)=30447.5 cm−1. The equilibrium bond angle for ã-state CH2+ is only 77.1°; as a result the asymmetric top κ value is close to 0, and the molecule is equally far from the oblate and prolate symmetric top limits in this electronic state. 相似文献
64.
Investigation of Brillouin effects in small-core holey optical fiber: lasing and scattering 总被引:6,自引:0,他引:6
We demonstrate for what is believed to be the first time a Brillouin laser based on a holey fiber (HF). Using a simple Fabry-Perot resonator scheme containing a 73.5-m-long highly nonlinear HF with an effective area of 2.85 microm(2) , we obtain a threshold of 125 mW and a slope efficiency of ~70% . Stimulated and spontaneous Brillouin scattering effects are investigated in the HF, and we show that the high lasing threshold is due mainly to reduction of the effective gain coefficient caused by structural nonuniformity along the fiber length. 相似文献
65.
Greater than 20%-efficient frequency doubling of 1532-nm nanosecond pulses in quasi-phase-matched germanosilicate optical fibers 总被引:2,自引:0,他引:2
Pruneri V Bonfrate G Kazansky PG Richardson DJ Broderick NG de Sandro JP Simonneau C Vidakovic P Levenson JA 《Optics letters》1999,24(4):208-210
We fabricated second-order nonlinear gratings in D-shaped germanosilicate fibers, using thermal poling and periodic electrodes defined by standard photolithography. These gratings, which are up to 75 mm long, were used for efficient quasi-phase-matched frequency doubling of 1.532-mum nanosecond pulses from a high-power erbium-doped fiber amplifier. Average second-harmonic powers as high as 6.8 mW and peak powers greater than 1.2 kW at 766 nm were generated, with average and peak conversion efficiencies as high as 21% and 30%, respectively. 相似文献
66.
M.A.H. Smith G.A. Harvey G.L. Pellett A. Goldman D.J. Richardson 《Journal of Molecular Spectroscopy》1984,105(1):105-112
N2-broadened halfwidths have been measured for 51 absorption lines belonging to the ν3 fundamental band of hydrogen cyanide (1H12C14N) near 3311 cm?1. The data were recorded at room temperature using a Fourier transform spectrometer with a nominal resolution of 0.06 cm?1. A nonlinear least-squares spectral-fitting procedure was used to obtain both line intensities and collision-broadened halfwidths from scans recorded at several different pressures. The N2-broadened halfwidths, determined for all lines with J ≤ 25 in both the P and R branches of the band, show the expected distribution with J for broadening by a nonpolar gas. The halfwidth values range from approximately 0.17 cm?1 atm?1 near the band center to 0.11 cm?1 atm?1 for high-J lines. The band intensity for the ν3 fundamental derived from these measurements is 236.2 ± 9.5 cm?2 atm?1 at 296 K, and empirical coefficients for the vibration-rotation interaction F-factor were also determined. 相似文献
67.
A.B. Gardner S. Howard T.C. Waddington R.M. Richardson J. Tomkinson 《Chemical physics》1981,57(3):453-460
Incoherent quasi-elastic neutron scattering has been used to study the reorientational motions of the cyclopentadienyl rings in ferrocene, nickelocene and ruthenocene. The results for ferrocene show that the activation energy for ring rotation drops above the 164 K phase transition to 4.4 ± 0.5 kJ mol?1 (which is approximately half its low temperature value) but the rings still appear to jump between only five orientations on the observable time scale. At room temperature, the rings in nickelocene appear to behave the same as in ferrocene but in ruthenocene they reorientate much less frequently and resemble those in ferrocene below 164 K. 相似文献
68.
R.S. Marjoribanks M.C. Richardson J. Delettrez S. Letzring W. Seka D.M. Villeneuve 《Optics Communications》1982,44(2):113-116
Preliminary experiments using an X-ray streak filter spectrometer employing a Au/CsI bifurcated photocathode to investigate the X-ray history of UV (350 nm) laser produced plasmas are reported. Novel use of the streak spectrometer permits a direct and precise fiducial record of the laser pulse to be made from specularly scattered laser light, in true streak time relative to the X-ray record. Initial data indicates a constant 700 eV temperature during the laser pulse; time-resolved particulars are compared to simulations made by the design code LILAC. 相似文献
69.
Joshi Shrikant V. Park Jin Y. Taylor P. R. Richardson L. S. 《Plasma Chemistry and Plasma Processing》1985,5(2):143-161
Plasma Chemistry and Plasma Processing - A new integral mean diffusivity is proposed for the calculation of the mass transfer rate around a small particle immersed in a thermal plasma gas.... 相似文献
70.
Leonard F. Richardson 《Mathematische Annalen》1979,239(3):229-240