全文获取类型
收费全文 | 394篇 |
免费 | 9篇 |
国内免费 | 3篇 |
专业分类
化学 | 288篇 |
晶体学 | 2篇 |
力学 | 7篇 |
数学 | 57篇 |
物理学 | 52篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2017年 | 5篇 |
2016年 | 13篇 |
2015年 | 7篇 |
2014年 | 2篇 |
2013年 | 20篇 |
2012年 | 15篇 |
2011年 | 16篇 |
2010年 | 13篇 |
2009年 | 10篇 |
2008年 | 16篇 |
2007年 | 15篇 |
2006年 | 18篇 |
2005年 | 17篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 21篇 |
2001年 | 11篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1996年 | 9篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 2篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 16篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1935年 | 4篇 |
1933年 | 3篇 |
1931年 | 2篇 |
排序方式: 共有406条查询结果,搜索用时 0 毫秒
131.
132.
133.
134.
135.
In low dielectric solvents such as pyridine or isopropylamine, sodium perchlorate interacts strongly with a variety of sugars. The interaction is best described as non-specific, with close proximity of the ionic partners maintained, as in a sugar-shared ion pair. 相似文献
136.
Daly AM Douglass KO Sarkozy LC Neill JL Muckle MT Zaleski DP Pate BH Kukolich SG 《The Journal of chemical physics》2011,135(15):154304
Microwave spectra of the propiolic acid-formic acid doubly hydrogen bonded complex were measured in the 1 GHz to 21 GHz range using four different Fourier transform spectrometers. Rotational spectra for seven isotopologues were obtained. For the parent isotopologue, a total of 138 a-dipole transitions and 28 b-dipole transitions were measured for which the a-dipole transitions exhibited splittings of a few MHz into pairs of lines and the b-type dipole transitions were split by ~580 MHz. The transitions assigned to this complex were fit to obtain rotational and distortion constants for both tunneling levels: A(0+) = 6005.289(8), B(0+) = 930.553(8), C(0+) = 803.9948(6) MHz, Δ(0+)(J) = 0.075(1), Δ(0+)(JK) = 0.71(1), and δ(0+)(j) = -0.010(1) kHz and A(0-) = 6005.275(8), B(0-) = 930.546(8), C(0-) = 803.9907(5) MHz, Δ(0-)(J) = 0.076(1), Δ(0-)(JK) = 0.70(2), and δ(0-)(j) = -0.008(1) kHz. Double resonance experiments were used on some transitions to verify assignments and to obtain splittings for cases when the b-dipole transitions were difficult to measure. The experimental difference in energy between the two tunneling states is 291.428(5) MHz for proton-proton exchange and 3.35(2) MHz for the deuterium-deuterium exchange. The vibration-rotation coupling constant between the two levels, F(ab), is 120.7(2) MHz for the proton-proton exchange. With one deuterium atom substituted in either of the hydrogen-bonding protons, the tunneling splittings were not observed for a-dipole transitions, supporting the assignment of the splitting to the concerted proton tunneling motion. The spectra were obtained using three Flygare-Balle type spectrometers and one chirped-pulse machine at the University of Virginia. Rotational constants and centrifugal distortion constants were obtained for HCOOH···HOOCCCH, H(13)COOH···HOOCCCH, HCOOD···HOOCCCH, HCOOH···DOOCCCH, HCOOD···DOOCCCH, DCOOH···HOOCCCH, and DCOOD···HOOCCCH. High-level ab initio calculations provided initial rotational constants for the complex, structural parameters, and some details of the proton tunneling potential energy surface. A least squares fit to the isotopic data reveals a planar structure that is slightly asymmetric in the OH distances. The formic OH···O propiolic hydrogen bond length is 1.8 ? and the propiolic OH···O formic hydrogen bond length is 1.6 ?, for the equilibrium configuration. The magnitude of the dipole moment was experimentally determined to be 1.95(3) × 10(-30) C m (0.584(8) D) for the 0(+) states and 1.92(5) × 10(-30) C m (0.576(14) D) for the 0(-) states. 相似文献
137.
138.
Mikhailova JM Buck A Borot A Schmid K Sears C Tsakiris GD Krausz F Veisz L 《Optics letters》2011,36(16):3145-3147
We report the generation of few-cycle multiterawatt light pulses with a temporal contrast of 10(10), when measured as close as 2 ps to the pulse's peak. Tens of picoseconds before the main pulse, the contrast value is expected to spread much beyond the measurement limit. Separate measurements of contrast improvement factors at different stages of the laser system indicate that real contrast values may reach 10(19) and 10(14), when measured 50 and 25 ps before the pulse's peak, respectively. The combination of the shortest pulse duration and the highest contrast renders our system a promising front-end architecture for future multipetawatt laser facilities. 相似文献
139.
M. Stschigol Rappaport A. Glaser O. Folin A. Svedberg L. Cuny J. Robert H. Cordebard F. W. Allen J. M. Luck P. Wenger Ch. Cimerman A. Maulbetsch K. Lang K. Hinsberg D. Laszlo M. T. Hanke K. K. Koessler J. M. Looney Z. Dische C. van Zijp F. Rappaport H. Engelberg und G. Plancher 《Fresenius' Journal of Analytical Chemistry》1935,101(7-8):312
Ohne Zusammenfassung 相似文献
140.
Rappport A. Glaser O. Folin A. Svedberg L. Cuny J. Robert H. Cordebard F. W. Allen J. M. Luck P. Wenger Ch. Cimerman A. Maulbetsch K. Lang K. Hinsberg D. Laszlo M. T. Hanke K. K. Koessler J. M. Looney Z. Dische C. van Zijp H. Engelberg und G. Plancher 《Fresenius' Journal of Analytical Chemistry》1935,101(7-8):312-320
Ohne Zusammenfassung 相似文献