全文获取类型
收费全文 | 1628篇 |
免费 | 32篇 |
国内免费 | 7篇 |
专业分类
化学 | 1282篇 |
晶体学 | 22篇 |
力学 | 12篇 |
数学 | 102篇 |
物理学 | 249篇 |
出版年
2023年 | 8篇 |
2021年 | 14篇 |
2020年 | 10篇 |
2019年 | 20篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2016年 | 30篇 |
2015年 | 18篇 |
2014年 | 21篇 |
2013年 | 100篇 |
2012年 | 58篇 |
2011年 | 72篇 |
2010年 | 44篇 |
2009年 | 59篇 |
2008年 | 69篇 |
2007年 | 72篇 |
2006年 | 60篇 |
2005年 | 75篇 |
2004年 | 66篇 |
2003年 | 61篇 |
2002年 | 85篇 |
2001年 | 35篇 |
2000年 | 35篇 |
1999年 | 23篇 |
1998年 | 29篇 |
1997年 | 16篇 |
1996年 | 30篇 |
1995年 | 13篇 |
1994年 | 17篇 |
1993年 | 16篇 |
1992年 | 24篇 |
1991年 | 28篇 |
1990年 | 18篇 |
1989年 | 20篇 |
1988年 | 13篇 |
1987年 | 18篇 |
1986年 | 12篇 |
1985年 | 36篇 |
1984年 | 25篇 |
1983年 | 19篇 |
1982年 | 31篇 |
1981年 | 20篇 |
1980年 | 31篇 |
1979年 | 31篇 |
1978年 | 31篇 |
1977年 | 31篇 |
1976年 | 14篇 |
1975年 | 21篇 |
1974年 | 14篇 |
1973年 | 15篇 |
排序方式: 共有1667条查询结果,搜索用时 15 毫秒
1.
Inside Cover: Photoinduced Formation of an Azobenzene‐Based CD‐Active Supramolecular Cyclic Dimer (Chem. Eur. J. 18/2015)
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
2.
3.
The interaction between azathioprine (AZ) and bovine serum albumin (BSA) is mainly due to hydrophobic binding according to the dependence of the binding constant on the ionic strength obtained by equilibrium dialysis. The binding constant and partition coefficient of AZ were smaller than those of warfarin, phenylbutazone and ibuprofen. Little variation in the proton chemical shift of AZ was observed whether there was an absence or presence of BSA (7.25 x 10(-5) M). The spin-lattice relaxation time (T1) of AZ decreased in the presence of BSA to 6-22%. The spin-spin relaxation rate (1/T2) of AZ increased 16-24 times for the methyl group and the imidazole ring and 8-13 times for the purine ring in the presence of BSA. The ratio of the spin-spin relaxation rate of the free AZ to the bound AZ ((1/T2)b/(1/T2)f) of the methyl group and the imidazole ring was 2-3 times larger than that of the purine ring. The binding of AZ to BSA was concluded to be mainly at the methyl group on the imidazole ring of AZ. 相似文献
4.
Noboru Nakatani 《Optical Review》2003,10(4):206-210
This paper describes a compulsorily phase locked differential interferometer using an orthogonally polarized light source of a modulated LD with high extinction ratio to reduce non-linearity of the interferometer caused by polarization cross-talk. The current modulated LD is used as a light source to make the interferometer compact and for the scanning phase of the interferometer. The interferometer is operated compulsorily at the maximum inclination point of the fringe intensity curve by fringe scanning and an electric system. A Wollaston prism of high extinction ratio (50 dB) is used to combine the polarizing beams and to make the polarization cross-talk very small. In one light source the polarized output beams are on the same propagation axis; in the other they have a small crossing angle (2.5 mrad ∼ 10 mrad) to completely exclude non-linearity of the interferometer causded by polarization cross-talk. Using jets of a gas mixture of nitrogen and ethylene, this interferometer was demonstrated to be useful in detecting the photothermal effect of a photothermal velocimeter under phase fluctuation in a turbulent flow. 相似文献
5.
Optical trapping forces of polystyrene microspheres are analyzed both theoretically and experimentally, and comparisons are
made between the two. Discrepancies are mainly caused by straight-ray approximation for axial trapping, and by trapping-position
vertical displacement due to gravity for transverse trapping. 相似文献
6.
Noboru Ito 《Graphs and Combinatorics》1989,5(1):229-234
Spectra of doubly regular asymmetric digraph of regular Hadamard type are determined. 相似文献
7.
Y. Masuda K. Asahi J. Kura Y. Mori H. Sato H. M. Shimizu 《Hyperfine Interactions》1992,74(1-4):149-157
An experimental scheme of the spin detailed balance in polarized neutron transmission through a polarized nuclear target is
discussed for the T-violation test. The value of the spin detailed balance is estimated by using the data of the scattering
amplitudes. The nuclear polarizations of proton,3He and139La are discussed for the T-violation experiment. 相似文献
8.
K. Ishikawa H. Nakano H. Masuda C. Kusano Y. Takahashi T. Hamagishi N. Endo 《Fiber and Integrated Optics》1992,11(4):385-394
A 10-Gbit/s optical receiver is developed using low-capacitance HBT IC technology. The HBT allows a cutoff frequency of 45 GHz and a maximum oscillation frequency of 70 GHz. The receiver contains an automatic gain-control amplifier IC with a gain of 16 dB, a bandwidth of 10.7 GHz, and a decision-circuit IC with an ambiguity of 66 mVp-p at a data rate of 10 Gbit/s. The sensitivity of this receiver is -26.5 dBm at a bit error rate of 10-9. Transmission over a 140-km fiber was achieved successfully. 相似文献
9.
Fumio Sanda Ritsuya Kawasaki Masashi Shiotsuki Toshio Masuda 《Journal of polymer science. Part A, Polymer chemistry》2007,45(19):4450-4458
Novel chiral acetylene monomers containing carbazole, 2‐ethynyl‐9‐[(S)‐2‐methylbutoxycarbonyl]carbazole ( 1 ), 3‐ethynyl‐9‐[(S)‐2‐methylbutoxycarbonyl]carbazole ( 2 ), 2‐ethynyl‐9‐[(S)‐2‐methylbutyl]carbazole ( 3 ), and 2‐ethynyl‐9‐[(S)‐4‐methylhexyl]carbazole ( 4 ) were synthesized and polymerized with [(nbd)RhCl]2? Et3N. The corresponding polyacetylenes with number‐average molecular weights ranging from 68,700 to 310,000 were obtained in good yields. Poly( 1 ) exhibited a large specific rotation and an intense Cotton effect in toluene, indicating that it formed a helix with predominantly one‐handed screw sense, while the other three polymers showed no evidence for taking a helical structure. Poly( 1 ) largely decreased the CD intensity upon heating from ?10 to 60 °C. Poly( 1 ) showed a Cotton effect in film state in a manner similar to solution state. No chiral amplification was observed in the copolymerization of 1 with achiral 2‐ethynyl‐9‐tert‐butoxycarbonylcarbazole ( 5 ). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4450–4458, 2007 相似文献
10.