全文获取类型
收费全文 | 5647篇 |
免费 | 142篇 |
国内免费 | 20篇 |
专业分类
化学 | 3966篇 |
晶体学 | 72篇 |
力学 | 78篇 |
数学 | 235篇 |
物理学 | 1458篇 |
出版年
2022年 | 33篇 |
2021年 | 35篇 |
2020年 | 59篇 |
2019年 | 69篇 |
2018年 | 58篇 |
2017年 | 38篇 |
2016年 | 91篇 |
2015年 | 100篇 |
2014年 | 124篇 |
2013年 | 263篇 |
2012年 | 274篇 |
2011年 | 290篇 |
2010年 | 173篇 |
2009年 | 171篇 |
2008年 | 305篇 |
2007年 | 254篇 |
2006年 | 277篇 |
2005年 | 264篇 |
2004年 | 259篇 |
2003年 | 204篇 |
2002年 | 206篇 |
2001年 | 149篇 |
2000年 | 161篇 |
1999年 | 87篇 |
1998年 | 62篇 |
1997年 | 67篇 |
1996年 | 65篇 |
1995年 | 43篇 |
1994年 | 68篇 |
1993年 | 89篇 |
1992年 | 94篇 |
1991年 | 74篇 |
1990年 | 63篇 |
1989年 | 55篇 |
1988年 | 72篇 |
1987年 | 73篇 |
1986年 | 77篇 |
1985年 | 106篇 |
1984年 | 94篇 |
1983年 | 40篇 |
1982年 | 70篇 |
1981年 | 74篇 |
1980年 | 68篇 |
1979年 | 61篇 |
1978年 | 52篇 |
1977年 | 64篇 |
1976年 | 53篇 |
1975年 | 39篇 |
1974年 | 50篇 |
1973年 | 31篇 |
排序方式: 共有5809条查询结果,搜索用时 15 毫秒
21.
In connection with a characteristic feature of the effective optical potential in the Dirac approach two types of time delays are considered in the relativistic eikonal approximation. One is obtained from the scattering amplitude and the other given by the wave packet motion in the interaction region. These time delays turn out to differ in sign at intermediate energies, in contrast to the agreement between corresponding nonrelativistic time delays. 相似文献
22.
23.
Y Yuda J Tanaka K Suzuki K Igarashi T Satoh 《Chemical & pharmaceutical bulletin》1991,39(4):1075-1077
Effects of non-steroidal anti-inflammatory drugs (NSAID: amfenac sodium, diclofenac sodium, indomethacin and ketoprofen) on the generation of superoxide anion (O2-) by isolated rat polymorphonuclear leukocytes (PMN) were studied spectrophotometrically using cytochrome c. The effects of these drugs were also studied on O2- production by the xanthine-xanthine oxidase and reduced nicotinamide adenine dinucleotide phosphate (NADPH)-NADPH oxidase systems. Amfenac sodium, at 0.1 mM, inhibited significantly O2- generation in rat PMN induced by opsonized zymosan. At 0.5 mM, diclofenac sodium and indomethacin inhibited the O2- generation in rat PMN. All of the above drugs slightly inhibited O2- production by the xanthine-xanthine oxidase system. On the other hand, O2- production by the NADPH-NADPH oxidase system was significantly inhibited by the addition of amfenac sodium, ketoprofen or indomethacin. These results suggest that non-steroidal anti-inflammatory drugs do not work as an O2- scavenger and block O2- production by the NADPH-NADPH oxidase system of rat PMN. It is concluded that amfenac sodium and the other drugs are able to inhibit granulocyte O2- production by blocking the activation of NADPH-oxidase. 相似文献
24.
A very short synthesis of chiral prostaglandin E1 methyl ester is described. 相似文献
25.
Watanabe G Umetsu K Yuasa I Sato M Sakabe M Naito E Yamanouchi H Suzuki T 《Electrophoresis》2001,22(3):418-420
We present a simple and rapid polymerase chain reaction (PCR)-based technique, termed consumed allele-specific primer analysis (CASPA), as a new strategy for single nucleotide polymorphism (SNP) analysis. The method involves the use of labeled allele-specific primers, differing in length, with several noncomplementary nucleotides added in the 5'-terminal region. After PCR amplification, the amounts of the remaining primers not incorporated into the PCR products are determined. Thus, nucleotide substitutions are identified by measuring the consumption of primers. In this study, the CASPA method was successfully applied to ABO genotyping. In the present method, the allele-specific primer only anneals with the target polymorphic site on the DNA, so it is not necessary to analyze the PCR products. Therefore, this method is only little affected by modification of the PCR products. The CASPA method is expected to be a useful tool for typing of SNPs. 相似文献
26.
Hiroki Higuchi Hidetoshi Kawai Masakazu Ohkita Takanori Suzuki 《Tetrahedron letters》2004,45(15):3027-3030
The newly prepared tetracyanoanthraquinodimethane (TCNAQ) derivatives 1a,b with a chiral auxiliary are good electron acceptors and exhibit weak circular dichroism (CD) based on the absorption of TCNAQ. The twin-type electron acceptor 1c with two TCNAQ units shows larger ellipticity by exciton coupling. UV-vis, CD, and fluorescence spectra were changed drastically upon electrochemical reduction of 1c, which demonstrates the unprecedented three-way-output response system. 相似文献
27.
Atsushi Ikeda Masaru Kawaguchi Yoshio Suzuki Tsukasa Hatano Munenori Numata Seiji Shinkai Akio Ohta Makoto Ohta 《Journal of inclusion phenomena and macrocyclic chemistry》2000,38(1-4):163-170
The calixarene-fullerene interaction,which causes only a slight change in the absorptionspectra, has been substantiated by calorimetricmeasurements: the H° values arecomparable with those obtained from the associationconstants estimated by a spectroscopic method. Furthermore, we determined the association constantbetween homooxacalix[3]arene and [60]fullerenederivatives with a porphyrin moiety by fluorescencespectra. 相似文献
28.
29.
30.
Yoshihiro Itoh Masamitsu Inoue Tomoko Takahashi Akira Hachimori Satoshi Suzuki 《Journal of polymer science. Part A, Polymer chemistry》1995,33(7):1069-1074
Alternating and random copolymers of 9-phenanthrylmethyl methacrylate or 2-(9-carbazolyl)ethyl methacrylate with styrene were synthesized and their fluorescence properties were examined. There was no noticeable difference in the spectral features of the alternating and random copolymers in tetrahydrofuran (THF), demonstrating that this type of polymers have no quenching sites in the polymer chains. The fluorescence quenching studies indicated that the alternating copolymers permitted singlet-state energy migration as efficiently as the corresponding random copolymers but less efficiently than the random copolymers with higher chromophore contents. These results strongly suggest that to be chromophores close to each other is most important for facilitation of an intramolecular energy migration. © 1995 John Wiley & Sons, Inc. 相似文献