全文获取类型
收费全文 | 2780篇 |
免费 | 82篇 |
国内免费 | 11篇 |
专业分类
化学 | 2082篇 |
晶体学 | 43篇 |
力学 | 39篇 |
数学 | 234篇 |
物理学 | 475篇 |
出版年
2023年 | 10篇 |
2021年 | 17篇 |
2020年 | 31篇 |
2019年 | 38篇 |
2018年 | 20篇 |
2017年 | 32篇 |
2016年 | 53篇 |
2015年 | 51篇 |
2014年 | 61篇 |
2013年 | 139篇 |
2012年 | 151篇 |
2011年 | 157篇 |
2010年 | 81篇 |
2009年 | 103篇 |
2008年 | 174篇 |
2007年 | 186篇 |
2006年 | 159篇 |
2005年 | 156篇 |
2004年 | 143篇 |
2003年 | 131篇 |
2002年 | 100篇 |
2001年 | 53篇 |
2000年 | 63篇 |
1999年 | 34篇 |
1998年 | 34篇 |
1997年 | 37篇 |
1996年 | 23篇 |
1995年 | 27篇 |
1994年 | 28篇 |
1993年 | 22篇 |
1992年 | 33篇 |
1991年 | 32篇 |
1990年 | 29篇 |
1989年 | 20篇 |
1988年 | 26篇 |
1987年 | 33篇 |
1986年 | 20篇 |
1985年 | 41篇 |
1984年 | 39篇 |
1983年 | 25篇 |
1982年 | 38篇 |
1981年 | 22篇 |
1980年 | 35篇 |
1979年 | 32篇 |
1978年 | 28篇 |
1977年 | 22篇 |
1976年 | 19篇 |
1975年 | 18篇 |
1974年 | 12篇 |
1973年 | 8篇 |
排序方式: 共有2873条查询结果,搜索用时 281 毫秒
11.
H. Ohta M. Kimata K. Koyama Y. Oshima M. Motokawa H. Nishikawa K. Kikuchi I. Ikemoto 《International Journal of Infrared and Millimeter Waves》2005,26(11):1525-1530
We have developed a new magneto-optical measurement system using a rotational cavity system equipped with a millimeter vector
network analyzer and a 14 T solenoid type super conducting magnet. The measurement can be performed in the transmission configuration
down to 1.6 K. The results of the precise angular dependence measurement of quasi-one-dimensional organic conductor (DMET)2I3 using the new system are shown, and its Fermi surface will be discussed in connection with the previous reports. 相似文献
12.
O-Glycosylations using thiomethyl glycosides as donors were compared under both frozen and unfrozen conditions. In the presence of MeOTf as a promoter, enormous rate acceleration was observed when the glycosylation was conducted in p-xylene below its freezing point. 相似文献
13.
Yue Liu Masahito Ohta Grozdena Todorova 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2007
We study here instability problems of standing waves for the nonlinear Klein–Gordon equations and solitary waves for the generalized Boussinesq equations. It is shown that those special wave solutions may be strongly unstable by blowup in finite time, depending on the range of the wave's frequency or the wave's speed of propagation and on the nonlinearity. 相似文献
14.
15.
Fiber-in-Tube Solid Phase Extraction (FIT-SPE) for Miniaturized Sample Preparation Process 总被引:2,自引:0,他引:2
A typical analytical separation procedure has several important steps: sample preparation, isolation, identification, quantitation, statistical evaluation and final decision. Each step is alwayscritical to obtain correct results to fulfill the analytical purpose. In these various steps sample 相似文献
16.
Takanori Suzuki Tomohiro Iwai Eisuke Ohta Hidetoshi Kawai Kenshu Fujiwara 《Tetrahedron letters》2007,48(20):3599-3603
Huge CD amplitude (A = +538) was attained by diastereomeric preference (50% de) for the title dication with two bis[4-(R)-sec-butoxyphenyl]methylium units in benzene at 23 °C. Intramolecular π-π stacking is the origin for effective transmission of point chirality to axial chirality to attain the chiroptical enhancement of 400-times. Thanks to the strong CD signaling, chiroptical changes upon electrolysis could be readily detected, thus realizing a new class of electrochiroptical response systems. Chiroptical properties could also be modified by solvent polarity. 相似文献
17.
3-Acetyl-2-oxazolone readily undergoes free-radical homopolymerization as well as telomerization with polyhalomethanes, in which low telomer formation is highly stereo- and regio-selective. 相似文献
18.
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
19.
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
20.
A chiral HWE reagent reacted with an alternative carbonyl group of meso-α-diketones of bicyclo[2.2.1] system to give non-racemic (Z)- and (E)-olefins, respectively. 相似文献