全文获取类型
收费全文 | 342篇 |
免费 | 7篇 |
专业分类
化学 | 209篇 |
晶体学 | 2篇 |
力学 | 6篇 |
数学 | 58篇 |
物理学 | 74篇 |
出版年
2023年 | 3篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2016年 | 8篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 16篇 |
2012年 | 15篇 |
2011年 | 12篇 |
2010年 | 11篇 |
2009年 | 16篇 |
2008年 | 16篇 |
2007年 | 17篇 |
2006年 | 15篇 |
2005年 | 12篇 |
2004年 | 20篇 |
2003年 | 10篇 |
2002年 | 10篇 |
2001年 | 18篇 |
2000年 | 12篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1974年 | 6篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1940年 | 2篇 |
1927年 | 2篇 |
1913年 | 2篇 |
排序方式: 共有349条查询结果,搜索用时 0 毫秒
191.
We present a rare example of a decay mechanism playing a constructive role in quantum information processing. We show how
the state of an atom trapped in a cavity can be teleported to a second atom trapped in a distant cavity by the joint detection
of photon leakage from the cavities. The scheme, which is probabilistic, requires only a single three level atom in a cavity.
We also show how this scheme can be modified to a teleportation with insurance. 相似文献
192.
High-resolution infrared studies of isotopic ethylenes below 2000 cm?1 have been commenced with a Nicolet FTIR spectrometer. Accurate vibration and rotation parameters for the v12 fundamentals of C2H4 and C2D4 are determined from spectra recorded with 0.05 cm?1 resolution. Excellent band contour simulations confirm that these bands are unperturbed throughout their range. 相似文献
193.
COMPOSITION OPERATOR ON BERS-TYPE SPACES 总被引:2,自引:0,他引:2
Necessary and sufficient conditions are established for a composition operator C f = fo to be bounded or compact on the Bers-type space Ha and the little Bers-type space Ha The boundedness and compactness of the composition operator C on A() are characterized, which generalize the case of C on Ha. 相似文献
194.
195.
196.
197.
Babin SA Karalekas V Harper P Podivilov EV Mezentsev VK Ania-Castañón JD Turitsyn SK 《Optics letters》2007,32(9):1135-1137
We present the first experimental demonstration of a resolvable mode structure with spacing c/2nL in the RF spectra of ultralong Raman fiber lasers. The longest ever demonstrated laser cavity (L=84 km), RF peaks of ~100 Hz width and spacing ~1 kHz have been observed at low intracavity powers. The width of the peaks increases linearly with growing intracavity power and is almost independent of fiber length. 相似文献
198.
199.
Three isomeric (benzyloxythienyl)oxazolines 9, 11 and 13 have been prepared and are found, upon treatment with a strong base, to undergo either Wittig rearrangement or intramolecular attack of the benzylic anion on the oxazoline function to give products derived from cleavage of the initially formed 3-aminothienofuran products. This pattern of reactivity is directly linked to the distance between the two reactive groups as determined by X-ray diffraction, with the greatest distance in 11 leading to exclusive Wittig rearrangement, the shortest distance in 13 giving exclusively cyclisation-derived products, and the intermediate distance in 9 leading to both processes being observed. The corresponding N-butyl amides were also obtained in two cases and one of these undergoes efficient Wittig rearrangement leading to a thieno[2,3-c]pyrrolone product. 相似文献
200.
Tim S. Bugni Lei Chen Mary Kay Harper William M. Maiese Gina C. Mangalindan 《Tetrahedron》2004,60(33):6981-6988
Acanthella spp. sponges have been prolific sources of highly functionalized diterpene antibiotics. Two Acanthella cavernosa sponges were investigated based on the activity of their extracts in a screen designed to detect bacterial folate biosynthesis inhibitors. Bacillus subtilis PY79 strain harboring a lacZ reporter gene fusion to a trimethoprim-responsive promoter (PpanB) was used for the screen. The ability of kalihinols to inhibit bacterial folate biosynthesis was investigated resulting in preliminary structure activity relationships. Eight kalihinol type diterpenes were isolated from two Philippine Acanthella cavernosa specimens including two new 10- and 15-formamido-kalihinol F analogs. 相似文献