全文获取类型
收费全文 | 1416篇 |
免费 | 57篇 |
国内免费 | 6篇 |
专业分类
化学 | 1125篇 |
晶体学 | 18篇 |
力学 | 23篇 |
数学 | 65篇 |
物理学 | 248篇 |
出版年
2023年 | 8篇 |
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 14篇 |
2019年 | 21篇 |
2018年 | 15篇 |
2017年 | 9篇 |
2016年 | 32篇 |
2015年 | 25篇 |
2014年 | 37篇 |
2013年 | 61篇 |
2012年 | 66篇 |
2011年 | 101篇 |
2010年 | 38篇 |
2009年 | 50篇 |
2008年 | 90篇 |
2007年 | 111篇 |
2006年 | 106篇 |
2005年 | 87篇 |
2004年 | 80篇 |
2003年 | 63篇 |
2002年 | 78篇 |
2001年 | 13篇 |
2000年 | 25篇 |
1999年 | 21篇 |
1998年 | 14篇 |
1997年 | 11篇 |
1996年 | 12篇 |
1995年 | 17篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 13篇 |
1991年 | 16篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 16篇 |
1987年 | 7篇 |
1986年 | 15篇 |
1985年 | 22篇 |
1984年 | 18篇 |
1983年 | 9篇 |
1982年 | 4篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 17篇 |
1978年 | 12篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 9篇 |
1974年 | 14篇 |
排序方式: 共有1479条查询结果,搜索用时 15 毫秒
971.
Masanori Ohya Denes Petz Noboru Watanabe 《International Journal of Theoretical Physics》1998,37(1):507-510
Quantum capacity is an important tool to analysethe performance of information transmission for quantumchannels. In this paper, the quantum capacities of theattenuation channel for PSK and OOK arediscussed. 相似文献
972.
Yasunari Noguchi Toshihisa Maruta Takeshi Yamane Nobutoshi Kiba 《Analytical sciences》2008,24(5):673-675
Using a spectrophotometric method after distillation separation is a standard test method widely employed for the determination of fluorine (F) in cement. Using a flow injection (FI) method after pyrolysis separation for quantification of fluorine in cement has recently been developed. Differences between the fluorine content values obtained by each method have been noted. This paper documents the differences between fluorine content (distillation F) measured spectrophotometrically after distillation and that (pyrolysis F) determined using the FI method after pyrolysis for fourteen commercial Portland cements and identifies a factor contributing to the differences between distillation F and pyrolysis F values. A highly significant relationship existed between distillation F and pyrolysis F values for fourteen cements (r(2) = 0.998, p < 0.001). 相似文献
973.
Shin''ichiro Asayama Takashi Noguchi Hideo Ogawa 《International Journal of Infrared and Millimeter Waves》2003,24(7):1091-1099
The design and performance of a fixed-tuned W-band SIS mixer with a wide band IF of 4.0-7.5 GHz is presented. Waveguide-to-stripline transition of the SIS mixer is designed using the lumped-gap-source port provided by HFSSTM. Measured receiver noise temperature is less than 25 K in the frequency range of 95-120 GHz, with a minimum value of around 19 K achieved. Mixer noise temperature is determined to be about 8.5 K, which is around twice the quantum limit (i.e., 2hw/k). In spite of the high IF frequencies (f
0 = 6 GHz), the performance of the SIS receiver is comparable or even superior to those of the best mechanically-tunable waveguide SIS receivers at low IF frequencies (f
0 = 1.5 GHz). This result suggests that it is easy to design waveguide-to-stripline transitions without scale-model measurements. 相似文献
974.
Yasuo Akita Tomofumi Noguchi Michinobu Sugimoto Akihiro Ohta 《Journal of heterocyclic chemistry》1986,23(5):1481-1485
Various chloropyrazines and their N-oxides were submitted to the cross-coupling reaction with ethylenes, such as styrene, ethyl acrylate and acrylonitrile. While the chloro-phenylpyrazines and 2-chloropyrazine 1-oxides were slugglish in this reaction system, the expected products were obtained from almost all the 2-chloro-3,6-dialkylpyrazines and their 4-oxides in moderate to good yields. 相似文献
975.
Masanori Tachiya 《Chemical physics letters》1975,33(2):289-292
A rigorous treatment of the kinetics of the quenching of luminescent probes in micelles using a generating function is presented. 相似文献
976.
Masanori Okawa 《Nuclear Physics B》1981,187(1):71-92
The anomalous dimensions of the flavor octet, three-body operators of twist four are evaluated at the one-loop level. The calculation is complicated due to the appearance of gauge non-invariant operators which are needed to renormalize gauge invariant operators. The mixing problem of these operators is resolved by using the Ward identities derived through the Becchi-Rouet-Stora transformations. Some comments on the evaluation of the coefficient functions are also made. 相似文献
977.
Masataka Ihara Kazuharu Noguchi Keiichiro Fukumoto Tetsuji Kametani 《Tetrahedron》1985,41(11):2109-2114
Photo-oxygenation of indole-3-acetaldehydes (28–30) followed by treatments with dimethyl sulphide and then dilute acetic acid gave 4-acylquinolines (13,31 and 32), respectively. 相似文献
978.
979.
Yasushi Kawata Kohki Takatoh Makoto Hasegawa Masanori Sakamoto 《Liquid crystals》1994,16(6):1027-1036
The alignment of nematic liquid crystals on micro-groove patterns was studied. It has been found that the order of the alignments is determined by the edge shape, spacing, and line pitch of the micro-groove patterns. On coarse patterns, with pitches greater than 2 μm, striped patterns of the liquid crystal alignment were observed using polarized light which manifested different orientations of the liquid crystals on the top, edge, and bottom of the grooves, respectively. On fine patterns, with pitches less than 2 μm, a uniform device-quality alignment has been realized, with which twisted nematic cells were constructed in combination with the rubbed alignment layer on the opposite substrate. Their viewing angle characteristics and tilt orientations of the director were also investigated. 相似文献
980.
Yukio Yokoyama Masanori Watanabe Sohei Horikoshi Hisakuni Sato 《Analytical sciences》2002,18(1):59-63
A low-capacity cation-exchange column was newly developed for the separation of amino acids. A highly cross-linked macro-porous polystyrene-divinylbenzene co-polymer was functionalized by a sulfoacylation reaction. The exchange capacity was controllable at the acylation step. The capacity between 55 and 60 micromol/column was adequate for the practical separations in acceptable retention times. The 5-microm base polymers having average pore diameters smaller than 3 nm gave satisfactory results, and those having 1.5-nm pore was most favorable. Several isocratic elution conditions at different pH values adjusted by phosphate buffer of mM order with or without acetonitrile could provide good separations for individual classes of amino acids, i.e., acidic, neutral, hydrophobic, and basic groups. The results provided fundamental data for constructing gradient elution systems required for the simultaneous separation of protein amino acids. 相似文献