全文获取类型
收费全文 | 957篇 |
免费 | 14篇 |
国内免费 | 2篇 |
专业分类
化学 | 722篇 |
晶体学 | 9篇 |
力学 | 14篇 |
数学 | 49篇 |
物理学 | 179篇 |
出版年
2023年 | 7篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2017年 | 4篇 |
2016年 | 16篇 |
2015年 | 11篇 |
2014年 | 7篇 |
2013年 | 40篇 |
2012年 | 39篇 |
2011年 | 42篇 |
2010年 | 16篇 |
2009年 | 22篇 |
2008年 | 47篇 |
2007年 | 36篇 |
2006年 | 55篇 |
2005年 | 43篇 |
2004年 | 44篇 |
2003年 | 23篇 |
2002年 | 53篇 |
2001年 | 18篇 |
2000年 | 6篇 |
1999年 | 13篇 |
1998年 | 15篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 13篇 |
1991年 | 17篇 |
1990年 | 11篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 17篇 |
1985年 | 21篇 |
1984年 | 23篇 |
1983年 | 7篇 |
1982年 | 25篇 |
1981年 | 19篇 |
1980年 | 17篇 |
1979年 | 22篇 |
1978年 | 18篇 |
1977年 | 20篇 |
1976年 | 13篇 |
1975年 | 11篇 |
1974年 | 13篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1971年 | 5篇 |
排序方式: 共有973条查询结果,搜索用时 281 毫秒
1.
Optical Review - This paper demonstrates a method to estimate the depth of a fluorescence object in turbid media using dual-wavelength excited photodynamic diagnosis, to aid in the invasion depth... 相似文献
2.
Cellulose derivative resin (CDR) suspensions containing resin particles of cellulose nitrate (CDR(CN)), cellulose acetate (CDR(CA)), or cellulose triacetate (CDR(CTA)) were prepared as the sorbent for resin suspension injection (RSI) electrothermal atomic absorption spectrometry (ETAAS), in which fine resin particles holding a desired trace element were directly injected into the graphite tube as the suspension. To compare the sorption ability, the distribution ratios of the Mo(VI)-phenylfluorone complex were measured between the aqueous phase and the sorbents, including the CDRs mentioned above and the finely divided anion exchange resin (AR). The results showed that the sorption ability decreases in the following order: CDR(CN) > or = AR > CDR(CA) > or = CDR(CTA). It was concluded that CDR(CN) was able to extract more than 98% of Mo(VI), and was suitable for RSI-ETAAS as well as AR. CDR(CN) was used for the determination of Mo in NIES certified reference materials, No. 10 Rice flour-unpolished; the results showed fairly good agreements between the analytical values and the certified values. 相似文献
3.
4.
An InGaAs/InAlAs five-layer asymmetric coupled quantum well (FACQW) is expected to show very large electrorefractive index change. n in a wideband transparency region. Band structures of the FACQW are analyzed with Luttinger-Kohn Hamiltonian. The electrorefractive characteristics of the FACQW are discussed. 相似文献
5.
E. S. Dy H. Kasai 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):241-245
We study the interaction between tin(II) porphyrin (SnPor) with platinum and
non-precious Group 8B metals (iron, cobalt and nickel) by density functional
theory and discuss the electronic properties of the resulting products. We
also model the interaction of the resulting compounds with water where
applicable. Our studies indicate that, SnPor-Ni possesses electronic
properties similar to SnPor-Pt, suggesting that it may possess similar
photocatalytic properties for reduction reactions, such as converting water
to hydrogen gas. 相似文献
6.
13C NMR studies showed that the population of the norcaradiene form of the title systems containing p-CH3O, H, and p-CF3 on the 7-aryl group increases in this order. The result is consistent with the prediction from the π-acceptor strength of the aryl group estimated by INDO calculations. 相似文献
7.
Masuhiro Tsukada Giuliano Freddi Nobutami Kasai 《Journal of Polymer Science.Polymer Physics》1994,32(7):1175-1182
The physical structure and compatibility of solution-cast Antheraea pernyi/Bombyx mori silk fibroin blend films were stuided by differential scanning calorimetry (DSC), thermomechanical (TMA) and thermogravimetric (TGA) analysis, dynamic viscoelastic measurement, infrared spectroscopy, and x-ray diffractometry. The DSC curves of the blend films showed independent endotherms at 280 and 358°C, corresponding to the thermal decomposition of B. mori and A. pernyi silk fibroins with random coil conformation. The intensity was roughly proportionate to the amount of each component in the blend. The thermal behavior corresponding to the conformational transitions induced by heating on A. pernyi and B. mori silk fibroins overlapped in the temperature range 190–230°C. Thermal expansion and contraction properties, as well as weight retention behavior of the blend films were intermediate between the pure components, as shown by the TMA and TGA curves. The onset temperature of the storage modulus curve decreased markedly, approaching that of B. mori silk fibroin film when the amount of this component in the blend increased. The loss modulus curve of the blend films showed two peaks at ca. 190 and 210°C, the former corresponding to B. mori, and the latter to A. pernyi silk fibroin. Infrared spectra of the blends exhibited absorption bands characteristic of the pure components overlapping in the spectral region 2000–400 cm?1. The x-ray diffraction peaks at 23 and 21.5°, attributed to the crystalline spacings of A. pernyi and B. mori fibroins, respectively, overlapped in the diffraction curves of the blends, while the peak at 11.4°, of A. pernyi, increased as the content of this fibroin in the blend increased. The degree of crystallinity, calculated from the x-ray diffraction curves, diminished as the amount of B. mori silk fibroin decreased. A low degree of compatibility exists between the two fibroins when they are cast from aqueous solution in the experimental conditions adopted in this work. © 1994 John Wiley & Sons, Inc. 相似文献
8.
Andrzej Skowronski Kunio Yamagata 《Proceedings of the American Mathematical Society》2004,132(3):659-667
We prove that a large class of self-injective algebras of tilted type is invariant under stable equivalences of module categories.
9.