全文获取类型
收费全文 | 1181篇 |
免费 | 24篇 |
国内免费 | 2篇 |
专业分类
化学 | 854篇 |
晶体学 | 4篇 |
力学 | 21篇 |
数学 | 91篇 |
物理学 | 237篇 |
出版年
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 13篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 18篇 |
2015年 | 19篇 |
2014年 | 23篇 |
2013年 | 67篇 |
2012年 | 53篇 |
2011年 | 56篇 |
2010年 | 29篇 |
2009年 | 29篇 |
2008年 | 69篇 |
2007年 | 51篇 |
2006年 | 60篇 |
2005年 | 60篇 |
2004年 | 46篇 |
2003年 | 53篇 |
2002年 | 42篇 |
2001年 | 40篇 |
2000年 | 27篇 |
1999年 | 18篇 |
1997年 | 13篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 17篇 |
1993年 | 7篇 |
1992年 | 25篇 |
1991年 | 17篇 |
1990年 | 24篇 |
1989年 | 16篇 |
1988年 | 15篇 |
1987年 | 18篇 |
1986年 | 22篇 |
1985年 | 32篇 |
1984年 | 13篇 |
1983年 | 13篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 15篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1977年 | 13篇 |
1976年 | 11篇 |
1975年 | 12篇 |
1974年 | 7篇 |
1973年 | 10篇 |
1969年 | 5篇 |
1968年 | 5篇 |
排序方式: 共有1207条查询结果,搜索用时 15 毫秒
991.
Manabu Iguchi Tsuneo Kondoh Tomomasa Uemura Fujio Yamamoto Zen-ichiro Morita 《Experiments in fluids》1994,16(3-4):255-262
Gas injection into a cylindrical bath through a centric bottom nozzle causes a swirl motion like rotary sloshing. Conditions indicating the initiation and cessation of the swirl motion have been made clear by many researchers. So far, the effect of the swirl motion on transport phenomena in the bath is not clear yet. The present study was made to clarify the bubble characteristics (void fraction, bubble frequency) and liquid flow characteristics (mean velocity, turbulence intensity, Reynolds shear stress) during swirl motion of bubbling jet. These two characteristics were investigated using an electro-resistivity probe and a two-dimensional LDV, respectively. 相似文献
992.
993.
GRAVITATION AND COSMOLOGY-PRINCIPLES AND APPLICATIONS OF THE GENERAL THEORY OF RELATIVITY, by S. Weinberg. John Wiley and Sons, Inc., New York, 1972. 657 pp. DIATOMIC MOLECULES, A CRITICAL BIBGIOGRAPHY OF SPECTROSCOPIC DATA/MOLÉCULES DIATOMIQUES, BIBLIOGRAPHIE CRITIQUE DE DONNÉES SPECTROSCOPIQUES, by R. F. Barrow. Editions du Centre National de la Recherche Scientifique, Paris, 1973.440 pp. (150 F). In French and English. NUCLEAR RESEARCH EMULSIONS (Vol. II.-Particle Behaviour & Emulsion Applications), by Walter H. Barkas. Academic Press, New York, 1973. THE OPTICAL INDUSTRY & SYSTEMS DIRECTORY 1973-1974 (20th edition). The Optical Publishing Co., Inc., Lenox Road, Suite 103R, Pittsfield, Ma. 01201, USA, ($35.00). AN INTRODUCTION TO THE THEORY OF LIQUID METALS, by T. E. Faber. Cambridge University Press. 相似文献
994.
M. Mihara K. Matsuta D. Nishimura M. Fukuda M. Yaguchi K. Iwamoto M. Wakabayashi Y. Kamisho J. Ohno Y. Morita T. Izumikawa T. Ohtsubo S. Suzuki M. Nagashima K. Abe T. Sakai S. Momota A. Ozawa D. Nagae Y. Ishibashi Y. Abe T. Niwa T. Nagatomo T. Minamisono M. K. Kubo A. Kitagawa M. Torikoshi M. Kanazawa S. Sato 《Hyperfine Interactions》2013,219(1-3):83-88
The structural and magnetic properties of Ho substituted BiFeO3 (BHFO) have been investigated using 57Fe Mössbauer spectroscopy and X-Ray diffraction (XRD) as a function of temperature. The Mössbauer spectrum obtained at room temperature for the as-synthesized BHFO sample exhibits broadened features due to the hyperfine field distributions related to the local variation of the neighbourhood of Fe and the magnetic hyperfine splitting patterns are indicative of magnetic ordering, mostly probably screwed or slightly antiferromagnetic. The spectrum was fitted with two superimposed asymmetric sextets, with similar hyperfine magnetic fields of Bhf1 = 48.0(1) T and Bhf2 = 49.0(1) T, corresponding to rhombohedral BFO. The hyperfine fields of the magnetic components decreased systematically with increasing temperature to a ‘field distribution’ just below the Néel temperature, TN ~ 600 K. At temperatures above 600 K, the spectral line associated with the Bi25FeO40 impurity phase dominates the spectra. This phase is confirmed by XRD measurements. From the temperature dependence of the site populations of the spectral components an average Debye temperature of θ D = 240(80) K has been estimated. 相似文献
995.
Y. Kamisho M. Mihara K. Matsuta M. Fukuda M. Yaguchi M. Wakabayashi Y. Morita J. Ohno S. Shinozaki R. Kambe Y. N. Zheng S. Y. Zhu T. Minamisono 《Hyperfine Interactions》2013,222(1-3):121-125
Measurements of the spin-spin relaxation time T 2 of the short-lived $\upbeta $ -emitter $^{12}B (I^{\uppi }$ = 1?+?, T 1/2 = 20 ms) in Si have been performed. By applying the spin echo method to $\upbeta $ -NMR measurements, the intrinsic T 2 for 12B in Si was successfully determined with the effect of the static magnetic field inhomogeneity removed. The temperature dependence of T 2 for 12B in Si shows that T 2 becomes longer with increasing temperature, which seems to reflect the effect of motional narrowing. 相似文献
996.
M. Yaguchi M. Mihara M. Fukuda D. Nishimura H. Uenishi K. Iwamoto M. Wakabayashi J. Ohno Y. Kamisho Y. Morita T. Minamisono K. Matsuta 《Hyperfine Interactions》2013,220(1-3):79-82
Spin polarization of short-lived β-emitting nucleus 29P (I π = 1/2?+?, T 1/2 = 4.14 s) produced through the 28P(d, n) 29P reaction was studied as functions of the incident deuteron energy E d and the recoil angle θ of 29P. New optimum condition was found at E d = 3.3 MeV and θ = 30° where polarization of 29P is ?(4.1 ± 0.7) %. 相似文献
997.
Takeshi TerauchiTaisaku Tanaka Taro TerauchiMasataka Morita Kyoko KimijimaIppei Sato Wataru ShojiYasuhiro Nakamura Tomoharu TsukadaTakashi Tsunoda Gouichirou HayashiNaoki Kanoh Masaya Nakata 《Tetrahedron letters》2003,44(42):7747-7751
Coupling of the C1C14 (AB) crotylstannane with the C15C28 (CD) aldehyde followed by stereochemical arrangements gave the C1C28 (ABCD) fragment of altohyrtin C. The C29C44 (EF) fragment was also prepared. The syntheses of these two fragments, both of which were identical with those prepared by the Smith group, constitute a formal total synthesis of altohyrtin C. 相似文献
998.
Pierluigi Contucci Satoshi Morita Hidetoshi Nishimori 《Journal of statistical physics》2006,122(2):303-312
For the Edwards-Anderson model we find an integral representation for some surface terms on the Nishimori line. Among the
results are expressions for the surface pressure for free and periodic boundary conditions and the adjacency pressure, i.e.,
the difference between the pressure of a box and the sum of the pressures of adjacent sub-boxes in which the box can been
decomposed. We show that all those terms indeed behave proportionally to the surface size and prove the existence in the thermodynamic
limit of the adjacency pressure. 相似文献
999.
Masaki Morita Yoshie Harada Kunihiro Iseki Shunsuke Izumi Atsunari Hiraya 《Analytical sciences》2005,21(9):1085-1090
We have studied amino acid formation by UV (193 nm) irradiation to organic molecules (amines, alcohols and amides) in aqueous solution. Among several types of detected amino acids, small aliphatic amino acids (Gly and alpha-, beta-Ala and alpha-, beta-, gamma-ABA) were quantitatively identified. Among these small aliphatic amino acids, certain amino acids were formed in its free form, even before hydrolysis, contrary to the results of UV irradiation to a gas mixture of CO, NH3, and H2O, where amino acids were hardly detected before hydrolysis. The species distribution of identified amino acids showed a dependence on the starting organic molecules, and also on the presence of ammonia. The formation processes of the identified small aliphatic amino acids were investigated with the aid of electrospray ionization (ESI) MS and MS/MS measurements of photoproducts. Possible formation processes of these amino acid precursors from each starting molecules are proposed. By identifying the amino acid precursor, which has a chiral carbon atom, a new possibility is suggested for asymmetric photosynthesis of amino acid from achiral organic molecules. 相似文献
1000.
Toshiyuki HamuraMasato Morita Takashi MatsumotoKeisuke Suzuki 《Tetrahedron letters》2003,44(1):167-170
Various functionalized biaryls are accessible via a simple two-step process. Treatment of alkenylcyclobutenones with aryllithium provides ring-opened trienes, which are smoothly cycloaromatized under thermal conditions. 相似文献