全文获取类型
收费全文 | 1194篇 |
免费 | 30篇 |
国内免费 | 3篇 |
专业分类
化学 | 875篇 |
晶体学 | 10篇 |
力学 | 9篇 |
数学 | 30篇 |
物理学 | 303篇 |
出版年
2022年 | 5篇 |
2021年 | 13篇 |
2020年 | 12篇 |
2019年 | 17篇 |
2018年 | 12篇 |
2017年 | 6篇 |
2016年 | 20篇 |
2015年 | 15篇 |
2014年 | 19篇 |
2013年 | 57篇 |
2012年 | 55篇 |
2011年 | 91篇 |
2010年 | 43篇 |
2009年 | 51篇 |
2008年 | 69篇 |
2007年 | 73篇 |
2006年 | 63篇 |
2005年 | 59篇 |
2004年 | 58篇 |
2003年 | 51篇 |
2002年 | 42篇 |
2001年 | 32篇 |
2000年 | 27篇 |
1999年 | 16篇 |
1998年 | 16篇 |
1997年 | 9篇 |
1996年 | 16篇 |
1995年 | 12篇 |
1994年 | 20篇 |
1993年 | 9篇 |
1992年 | 20篇 |
1991年 | 12篇 |
1990年 | 16篇 |
1989年 | 10篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 24篇 |
1984年 | 13篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 16篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 9篇 |
排序方式: 共有1227条查询结果,搜索用时 15 毫秒
991.
T. Sonoda M. Wada H. Tomita C. Sakamoto T. Takatsuka T. Noto H. Iimura Y. Matsuo T. Kubo T. Shinozuka T. Wakui H. Mita S. Naimi T. Furukawa Y. Itou P. Schury H. Miyatake S. Jeong H. Ishiyama Y. Watanabe Y. Hirayama 《Hyperfine Interactions》2013,216(1-3):103-107
We developed a prototype laser ionization gas cell with a beam extraction system. This device is for use of PArasitic Laser Ion-Source (PALIS), which will be implemented into RIKEN’s fragment separator, BigRIPS as a part of SLOWRI. Off-line resonant laser ionization for stable Co, Cu, Fe, Ni, Ti, Nb, Sn, In and Pd inside the gas cell, ion extraction and transport to the high-vacuum region via SPIG and QMS have been confirmed (Sonoda et al, Nucl Instrum Meth B 295:1, 2013). 相似文献
992.
The spin polarizations of hadrons inclusively produced by pp, γp and νp collisions are studied by the quark rearrangement model. The present model is a phenomenological one based on the relativistic spin equations of motion and using the quark distribution functions in hadrons and photon. A general success of the model is demonstrated. We find usefulness of the present formulation for studying the dynamics producing spin asymmetry distributions and the statics determining signs and magnitudes of the spin polarization by reflecting the characteristic quark structure in hadrons. 相似文献
993.
This paper is concerned with the initial value problem for semilinear systems of wave equations. First we show a global existence
result for small amplitude solutions to the systems. Then we study asymptotic behavior of the global solution. We underline
that ``modified' free profiles are obtained for all global solutions to the systems even in the case where the free profile
might not exist. Moreover, we prove non–existence of any free profiles for the global solution in some cases where the effect
of the nonlinearity is strong enough.
The first author was partially supported by Grant-in-Aid for Science Research (14740114), JSPS. 相似文献
994.
Naoyuki Takahashi Takato Nakumura Yoshinori Kubo Katsumi Tamanuki 《Journal of Physics and Chemistry of Solids》2005,66(7):1145-1149
Crystalline quartz films with an AT-cut plane have been grown by catalyst-enhanced vapor-phase epitaxy, at atmospheric pressure, using two quartz buffer layers on a sapphire (110) substrate. In this method, the first quartz buffer layer was deposited on the sapphire (110) substrate at 773 K. After annealing at 823 K, the second buffer layer was deposited at 723 K. The crystal quartz epitaxial layer was then grown at 843 K. The X-ray full-width-at-half-maximum (FWHM) value of the crystalline quartz film obtained was smaller than that of crystalline quartz prepared using a hydrothermal process. The crystalline quality of the quartz films was dependent on the thickness of the buffer layers. Furthermore, it was found that angle control of the cut plane depended on the film thickness of the second buffer layer. The quartz films grown by vapor phase epitaxy show good oscillation characteristics at room temperature. 相似文献
995.
H2O2 generated and released from TiO2 photocatalysts to the gas phase was detected. A flow-through cell packed with TiO2-coated glass beads was irradiated with UV light, and the gas flowing out of the cell was flushed through a collecting solution containing 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulforic acid) diammonium salt (ABTS) and peroxidase. Oxidative coloration of ABTS was observed only in the absence of catalase, indicating the presence of H2O2 in the gas. The quantum yield of the H2O2 generation was estimated to be > 1 x 10(-7). The detected amount of H2O2 decreased as the TiO2 thickness decreased. H2O2 was not detected when dry air or nitrogen was used. 相似文献
996.
Effect of branching in base polymer on ionic conductivity in hyperbranched polymer electrolytes 总被引:3,自引:0,他引:3
Takahito Itoh Yoshiaki Ichikawa Nobuyuki Hirata Takahiro Uno Masataka Kubo Osamu Yamamoto 《Solid State Ionics》2002,150(3-4):337-345
Novel hyperbranched polymer, poly[bis(diethylene glycol)benzoate] capped with a 3,5-bis[(3′,6′,9′-trioxodecyl)oxy]benzoyl group (poly-Bz1a), was prepared, and its polymer electrolyte with LiN(CF3SO2)2, poly-Bz1a/LiN(CF3SO2)2 electrolyte, was all evaluated in thermal properties, ionic conductivity, and electrochemical stability window. The poly-Bz1a/LiN(CF3SO2)2 electrolyte exhibited higher ionic conductivity compared with a polymer electrolyte based on poly[bis(diethylene glycol)benzoate] capped with an acetyl group (poly-Ac1a), and the ionic conductivity of poly-Bz1a/LiN(CF3SO2)2 electrolyte was to be 7×10−4 S cm−1 at 80 °C and 1×10−6 S cm−1 at 30 °C, respectively. The existence of a 3,5-bis[(3′,6′,9′-trioxodecyl)oxy]benzoyl group as a branching unit present at ends in the base polymer improved significantly ionic conductivity of the hyperbranched polymer electrolytes. The polymer electrolyte exhibited the electrochemical stability window of 4.2 V at 70 °C and was stable until 300 °C. 相似文献
997.
A study on single fuel droplets combustion in vertical direct current electric fields 总被引:1,自引:0,他引:1
Osamu Imamura Yasuyuki Kubo Jun Osaka Junichi Sato Mitsuhiro Tsue Michikata Kono 《Proceedings of the Combustion Institute》2005,30(2):1949-1956
Both the electric force working on flames and the natural buoyancy are body forces, so there is a possibility to control the natural buoyancy by applying than electric field. It is important to discuss the body force in the flame because it induces the convective flow around flames. In this circumstance, combustion behavior of single droplets in vertical direct current electric fields was investigated. Ethanol, n-octane, and toluene were used as fuels, and the flame shape and the burning rate constants were measured. The distance between electrodes is 50 mm, and the applied voltage ranged between −4 and 6 kV as the bottom electrode is ground. When the direction of the electric field is opposite to the natural buoyancy direction, the applied voltage exists that make the flame symmetrical in the vertical direction, and the burning rate constants have local minima for ethanol and n-octane at the voltage. However, the minimum burning rate constants are larger than those under microgravity. This means that the electric force roughly balances with natural buoyancy, but it does not completely balance with the same. When the direction of the electric field is in the same direction as the natural buoyancy, there exist some experimental results, which cannot be explained by the assumption that electric field induces the body force only through the positive ions. This suggests that the additional body force is induced by the negative ions. The effects of negative charged soot particles on the combustion behavior are also discussed for the sooty flame of toluene. 相似文献
998.
Hiromitsu Terao Yoshihiro Furukawa Satomi Miki Fukue Tajima Masao Hashimoto 《Hyperfine Interactions》2004,159(1-4):211-216
The crystal structure of [C(NH2)3]3Sb2Br9 was determined at 143 K: monoclinic, space group C2/c, Z = 4, a = 15.695 (3), b = 9.039(2), c = 18.364(3) Å, β = 96.94(1)°. The structure consists of two crystallographically independent guanidinium ions and two-dimensional corrugated sheets of (Sb2Br9 3?) n , in which SbBr6 octahedra are connected through three bridging Br atoms each other. One of the cations situates in a cavity of the (Sb2Br9 3?) n layer with statistical disorder, while the other situates between the layers without disorder. Three 81Br NQR resonance lines were assignable to terminal Br atoms, while only one line was found for two inequivalent bridging Br atoms. All the 81Br NQR resonance lines were subjected to fade-out at low temperatures. The temperature dependence curve of 1H NMR T 1 showed well defined two minima, which were explained by postulating the C3 reorientations of two types of cations with very different activation energies. The DTA (DSC) measurement revealed a phase transition of a first-order type at 444 K. 相似文献
999.
Y. Hirobe Y. Kubo K. Kouyama H. Kunugita K. Ema H. Kuwahara 《Solid State Communications》2005,133(7):449-453
Photoinduced effects in a single crystal of bilayered manganites, La2−2xSr1+2xMn2O7 (x=0.38), were investigated in a wide range of temperatures by pump-probe measurement at a photon energy of 1.6 eV. In a ferromagnetic metallic state, significant enhancement of positive rise in differential reflectivity with a slow relaxing time of 100 ps was observed just below TC=127 K, indicating that the reflectivity change with the slow relaxation time constant is induced by laser heating. We have also observed an unconventional fast relaxing component that has a time constant of the order of 10 ps. This fast relaxing component, whose absolute value has an asymmetric peak at TC, is presumably due to short-range correlation of Jahn-Teller distortion. 相似文献
1000.
Polarity‐Dependent Isomerization of an Unsymmetrical Overcrowded Ethylene Promoted by Zwitterionic Contribution in the Twisted Isomer 下载免费PDF全文
Dr. Yasukazu Hirao Nobuhiro Nagamachi Katsuma Hosoi Prof. Dr. Takashi Kubo 《化学:亚洲杂志》2018,13(5):510-514
The twisted form of bianthrone is known as a metastable state provided by a photo‐induced or thermal‐induced isomerization of the folded form, and thus prevents the isolation and the detailed analysis of its electronic structure. In this study, an unsymmetrical bianthrone ( 2 ), consisting of the electron‐withdrawing anthrone and electron‐donating acridane, have been synthesized and shown to exhibit a solvent‐polarity‐dependent isomerization reaction between the folded and twisted isomers. With increasing the polarity of the solvent, 2 showed an isomerization reaction from the folded form to the twisted form. The stabilization of the twisted isomer in polar solvents can be interpreted as proof of its relatively large zwitterionic character. The DMF solution of 2 displayed paramagnetically‐broadened NMR signals from the thermally populated triplet state resulting from rotation of the weakened ethylenic double bond of the twisted isomer. 相似文献