全文获取类型
收费全文 | 495篇 |
免费 | 2篇 |
专业分类
化学 | 402篇 |
晶体学 | 2篇 |
数学 | 22篇 |
物理学 | 71篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2016年 | 7篇 |
2014年 | 3篇 |
2013年 | 13篇 |
2012年 | 10篇 |
2011年 | 18篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 21篇 |
2007年 | 28篇 |
2006年 | 26篇 |
2005年 | 20篇 |
2004年 | 18篇 |
2003年 | 23篇 |
2002年 | 32篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 10篇 |
1995年 | 2篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 24篇 |
1981年 | 11篇 |
1980年 | 15篇 |
1979年 | 7篇 |
1978年 | 14篇 |
1977年 | 18篇 |
1976年 | 15篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 15篇 |
1972年 | 2篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1927年 | 1篇 |
排序方式: 共有497条查询结果,搜索用时 156 毫秒
491.
Takamasa Seta Hiromichi Hoshina Iwao Hosako Stefan Loßow Mattias Ekström Donal Murtagh 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(1):144-150
The air induced broadening coefficients of the pure rotational transitions of H2O at 556.936 GHz (110←101), and 752.033 GHz (211←202) were measured by terahertz time-domain spectroscopy. The air broadening coefficient was determined to be for the 556.936 GHz line and for the 752.033 GHz line, respectively. The present broadening coefficients for the 556.936 GHz water line are significantly smaller than those of Markov and Krupnov [Measurements of the pressure shift of the 1(10)-1(01) water line at 556.936 GHz produced by mixtures of gases. J Mol Spect 1995:172;211-4] but relatively close to the values of the HITRAN database. The measured data may improve the accuracy of the abundance of water vapor retrieved from spectra obtained by the Odin/SMR satellite instrument. The effect on the satellite retrieval processing is discussed. 相似文献
492.
493.
Morohashi I Sakamoto T Sotobayashi H Kawanishi T Hosako I Tsuchiya M 《Optics letters》2008,33(11):1192-1194
By combining a Mach-Zehnder-modulator-based flat comb generator (MZ-FCG) with a dispersion-flattened dispersion-decreasing fiber, femtosecond pulses have been generated from a cw light. Near-Fourier-transform-limit picosecond pulses generated from the MZ-FCG were compressed into femtosecond order by pulse compression. Our system enables flexible tuning of the repetition rate and pulse width, because those depend on the driving signal of the MZ-FCG. Pulse trains of 200 fs width were continuously and stably generated without mode hopping, with a repetition rate range from 5 to 17 GHz. Our system consists of a modulator and compression fiber; thus, the configuration is simpler and more stable. 相似文献
494.
Yuki Tsujikawa Makoto Shoji Masashi Hamada Tomoya Takeda Izumi Mochizuki Toshio Hyodo Iwao Matsuda Akari Takayama 《Molecules (Basel, Switzerland)》2022,27(13)
We have investigated the structure of χ3-borophene on Ag(111), a monolayer material of boron atoms, via total-reflection high-energy positron diffraction (TRHEPD). By comparing the experimental rocking-curves with ones for several structures calculated by using dynamical diffraction theory, we confirmed that the χ3-borophene layer has a flat structure. The distance from the topmost layer of the metal crystal is 2.4 Å, which is consistent with results reported by X-ray standing wave-excited X-ray photoelectron spectroscopy. We also demonstrated that the in-plane structure of χ3-borophene is compatible with the theoretical predictions. These structural properties indicate that χ3-borophene belongs to a group of epitaxial monolayer sheets, such as graphene, which have weak interactions with the substrates. 相似文献
495.
Yusuke Hioki Dr. Tatsuya Sato Dr. Toyoki Iwao Junya Ikuma Dr. Atsushi Kawamura Dr. Takayuki Ohyoshi Dr. Yuta Tsunematsu Dr. Masaki Kita 《European journal of organic chemistry》2023,26(12):e202300084
The shell-less herbivorous marine mollusk (sea hare) Aplysia kurodai is known to contain a variety of bioactive substances. While these compounds have been thought to originate from sea algae or their associated microbes, most of their origin and acquisition pathways are still unclear. Six new cytotoxic aplaminone derivatives, bromodopamine-terpenoid hybrid molecules, were isolated from A. kurodai. Among them, isoaplaminone had a reverse prenyl group at the C15 aliphatic chain, which is a rare structural feature from the viewpoint of terpenoid biosynthesis. Investigation for chemical components in A. kurodai and the sea algae collected at several different locations revealed that two major aplaminones were contained in the Laurencia complex species at specific sites. Our chemical and ecological studies provide new insights into the origin of marine alkaloid toxins and their dynamism through the food chain. 相似文献
496.
497.
Binary random copolymers of styrene with butadiene, methyl methacrylate, and t-butyl methacrylate, and styrene-methyl methacrylate-acrylonitrile random terpolymers were separated by adsorption chromatography. The HPLC conditions required for the sample to adsorb to the stationary phase are discussed. Sequence length as well as composition affected the elution volume of block and graft copolymers of styrene and butadiene. A mixture of terpolymers having different composition was separated to each component by cross-fractionation using two types of adsorption chromatography. 相似文献