全文获取类型
收费全文 | 1241篇 |
免费 | 25篇 |
国内免费 | 4篇 |
专业分类
化学 | 881篇 |
晶体学 | 13篇 |
力学 | 16篇 |
数学 | 63篇 |
物理学 | 297篇 |
出版年
2021年 | 4篇 |
2020年 | 11篇 |
2019年 | 14篇 |
2018年 | 6篇 |
2017年 | 11篇 |
2016年 | 19篇 |
2015年 | 19篇 |
2014年 | 29篇 |
2013年 | 51篇 |
2012年 | 46篇 |
2011年 | 52篇 |
2010年 | 27篇 |
2009年 | 43篇 |
2008年 | 66篇 |
2007年 | 84篇 |
2006年 | 63篇 |
2005年 | 69篇 |
2004年 | 59篇 |
2003年 | 55篇 |
2002年 | 37篇 |
2001年 | 41篇 |
2000年 | 35篇 |
1999年 | 22篇 |
1998年 | 10篇 |
1997年 | 20篇 |
1996年 | 12篇 |
1995年 | 15篇 |
1994年 | 21篇 |
1993年 | 13篇 |
1992年 | 20篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 10篇 |
1988年 | 19篇 |
1987年 | 18篇 |
1986年 | 14篇 |
1985年 | 27篇 |
1984年 | 25篇 |
1983年 | 11篇 |
1982年 | 18篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 17篇 |
1978年 | 14篇 |
1977年 | 17篇 |
1976年 | 8篇 |
1975年 | 10篇 |
1974年 | 7篇 |
1970年 | 2篇 |
1965年 | 4篇 |
排序方式: 共有1270条查询结果,搜索用时 15 毫秒
171.
172.
Masuhiro Yamaguchi Hiroyuki Ikeda Tokio Ohta Tsuneaki Goto Toshikazu Katayama 《Solid State Communications》1985,53(4):383-385
The magnetization curves for the Y2Co7Hx and the YCo3Hx systems have been measured at 4.2 K in the pulsed high magnetic fields up to 280 kOe. The metamagnetic transition is observed in the β and the γ hydrides except for Y2Co7H3 and YCo3H1, which is interpreted in terms of the itinerant electron metamagnetism. 相似文献
173.
Vapor—liquid equilibrium data for the ternary ethanol—2-butanone—benzene system and its constituent binary systems at 298.15 K are presented. The results are correlated with the Wilson, original and modified UNIQUAC equations and the UNIFAC group contribution method. 相似文献
174.
We provide proper mapping-characterizations of some embedding-like properties weaker than -embedding. For instance, we show that a subset A of a space X is -embedded in X if and only if for every continuous map g: A → Y into a Banach space Y of weight w(Y) ⩽ λ, there exists a continuous set-valued mapping φ of X into the nonempty compact subsets of Y such that g is a selection for φ∣A (i.e., g(x) ∈ φ(x) for every x ∈ A). On the other hand, we show that a subset A is C*-embedded in X if and only if for every continuous set-valued mapping φ of X into the non-empty compact subsets of a Banach space Y, every continuous selection g: A → Y for φ∣A is continuously extendable to the whole of X. Combining both results we get the well-known mapping-characterization of -embedding which makes more transparent the relation ‘’. Other weak components of -embedding are described in terms of expansions and selections, possible applications are demonstrated as well. 相似文献
175.
Nakano M Kishi R Nakagawa N Ohta S Takahashi H Furukawa S Kamada K Ohta K Champagne B Botek E Yamada S Yamaguchi K 《The journal of physical chemistry. A》2006,110(12):4238-4243
The second hyperpolarizabilities of bisimidazole- and bistriazole-benzene compounds have been calculated at different levels of approximation to unravel the effects of diradical character as well as of charge and spin multiplicity. The largest second hyperpolarizabilities are associated with intermediate diradical character, provided positive charging does not compensate for this effect. For the neutral diradical bisimidazole compound, the singlet diradical species possesses a second hyperpolarizability two to three times larger than the corresponding triplet, demonstrating the possibility of spin state control of the third-order NLO responses for diradical species. 相似文献
176.
Mehata MS Iimori T Yoshizawa T Ohta N 《The journal of physical chemistry. A》2006,110(38):10985-10991
Stark absorption spectroscopy was applied to 6-hydroxyquinoline (6-HQ) doped in polymer films of poly(methyl methacrylate) (PMMA) and poly(vinyl alcohol) (PVA) at temperatures of 50-300 K. The electroabsorption (E-A) spectrum of 6-HQ markedly depends on temperature in a PMMA film. The polarization dependence as well as the temperature dependence of the E-A spectra reveals that 6-HQ is oriented along the direction of the applied electric field at room temperature in a PMMA film. As the temperature becomes lower, the field-induced orientation of 6-HQ is restricted, and only the Stark shift induced by a change in electric dipole moment and in molecular polarizability is observed. On the other hand, E-A spectra of 6-HQ doped in a PVA film are essentially independent of temperature, suggesting that 6-HQ is not oriented along the electric field even at room temperature in PVA. These results show that the molecular motion of 6-HQ in a polymer film is very sensitive to the microenvironment of the surrounding matrix. 相似文献
177.
Ara AM Iimori T Yoshizawa T Nakabayashi T Ohta N 《The journal of physical chemistry. B》2006,110(47):23669-23677
Fluorescence spectra and electrofluorescence spectra (plots of the electric field-induced change in fluorescence intensity as a function of wavelength) have been measured at different temperatures for pyrene butyric acid (PBA) in a PMMA film at different concentrations. At a low concentration of 0.5 mol % where fluorescence emitted from the locally excited state of PBA (LE fluorescence) is dominant, LE fluorescence spectra show only the Stark shift in the presence of an electric field (F), which results from the difference in molecular polarizability between the ground and emitting states. At a high concentration of 10 mol % where the so-called sandwich-type excimer fluorescence (EX(1)) is dominant, both EX(1) and LE fluorescence are quenched by F. Another fluorescence assigned to a partially overlapped excimer (EX(2)) also exists at room temperature, and this emission is enhanced by F. As the temperature decreases, three fluorescence emissions whose electric field effects are different from each other become clear besides EX(1) and LE fluorescence, indicating that at least five fluorescence components exist at high concentrations at low temperatures. At a medium concentration of 5 mol % where EX(1) is comparable in intensity to the LE fluorescence, the intensity of EX(1) is not affected by F at any temperature, but LE fluorescence and EX(2) are markedly influenced by F at room temperature, and four fluorescence emissions are confirmed at low temperatures. 相似文献
178.
Shimada T Kondoh H Iwasaki M Nakai I Nagasaka M Amemiya K Orita H Ohta T 《The journal of physical chemistry. B》2006,110(41):20507-20512
The adsorption structure of NO on the reconstructed Pt(110)-(1 x 2) surface was studied with X-ray photoelectron spectroscopy (XPS), X-ray photoelectron diffraction (XPD), low-energy scanned-angle photoelectron diffraction (LESA-PD), and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The experiments were performed at 180 K, where no surface lifting from (1 x 2) to (1 x 1) takes place after NO adsorption. XPS indicates that the (1 x 2) unit cell of the Pt(110) surface contains 1.5 NO molecules at the saturated coverage. XPD and LESA-PD analyses allow us to propose a structural model for the NO adlayer, where two-thirds of the NO molecules in the (1 x 2) unit cell are adsorbed on the atop site of the close-packed Pt rows (ridges) along the [10] direction with an inclined geometry and one-third of the NO molecules adsorb on the bridge site between the Pt ridges with an upright configuration. This model is supported by the N K-edge NEXAFS experiments and is consistent with the recently reported model based on the density functional theory (Orita, H.; Nakamura, I.; Fujitani, T. J. Phys. Chem. B 2005, 109, 10312). 相似文献
179.
M. Tanaka H. Kohri T. Ohta M. Yosoi M. Fujiwara K. Ueda S. Imoto K. Takamatsu J. -P. Didélez G. Frossati A. de Waard Yu. Kiselev S. Makino H. Fujimura K. Fukushima S. Fukushima H. Kondoh 《Physics of Particles and Nuclei》2013,44(6):959-963
The project in producing the hyperpolarized 3He and 19F are addressed in pursuit of radiation free medical diagnosis. The program for production of the hyperpolarized 3He by the brute force method with the Pomeranchuk cooling and the rapid melting of the solid 3He started a few years ago, and is still on the way, while a new program for production of the hyperpolarized 19F by means of the PHIP (ParaHydrogen Induced Polarization) has just got started. Particular attention is placed upon a new idea of the hyperpolarization catalyst to be used for 19F. 相似文献
180.
John?Mann Dezheng?Sun Quan?Ma Jen-Ru?Chen Edwin?Preciado Taisuke?Ohta Bogdan?Diaconescu Koichi?Yamaguchi Tai?Tran Michelle?Wurch KatieMarie?Magnone Tony F.?Heinz Gary L.?Kellogg Roland?Kawakami Ludwig?BartelsEmail author 《The European Physical Journal B - Condensed Matter and Complex Systems》2013,86(5):226
Areas of single-layer MoS2 film can be prepared in a tube furnace without the need for temperature control. The films were characterized by means of Raman spectroscopy, photoluminescence, low-energy electron diffraction and microscopy, and X-ray photoelectron spectroscopy and mapping. Transport measurements show n-doped material with a mobility of 0.26 cm2 V-1 s-1. 相似文献