全文获取类型
收费全文 | 1337篇 |
免费 | 42篇 |
国内免费 | 5篇 |
专业分类
化学 | 1012篇 |
晶体学 | 21篇 |
力学 | 4篇 |
数学 | 26篇 |
物理学 | 321篇 |
出版年
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 7篇 |
2018年 | 9篇 |
2017年 | 10篇 |
2016年 | 26篇 |
2015年 | 20篇 |
2014年 | 30篇 |
2013年 | 71篇 |
2012年 | 48篇 |
2011年 | 40篇 |
2010年 | 28篇 |
2009年 | 38篇 |
2008年 | 47篇 |
2007年 | 68篇 |
2006年 | 62篇 |
2005年 | 79篇 |
2004年 | 58篇 |
2003年 | 61篇 |
2002年 | 53篇 |
2001年 | 43篇 |
2000年 | 47篇 |
1999年 | 25篇 |
1998年 | 18篇 |
1997年 | 18篇 |
1996年 | 20篇 |
1995年 | 11篇 |
1994年 | 17篇 |
1993年 | 24篇 |
1992年 | 26篇 |
1991年 | 11篇 |
1990年 | 18篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 23篇 |
1986年 | 21篇 |
1985年 | 31篇 |
1984年 | 25篇 |
1983年 | 11篇 |
1982年 | 23篇 |
1981年 | 17篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 14篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1975年 | 15篇 |
1974年 | 17篇 |
1973年 | 11篇 |
1972年 | 6篇 |
排序方式: 共有1384条查询结果,搜索用时 421 毫秒
101.
Masahiro Yamashita Daisuke Kawakami Satoshi Matsunaga Yoshio Nakayama Mari Sasaki Shinya Takaishi Fumiyasu Iwahori Hitoshi Miyasaka Ken‐ichi Sugiura Yoshiki Wada Hiroshi Miyamae Hiroyuki Matsuzaki Hiroshi Okamoto Hisaaki Tanaka Kazuhiro Marumoto Shin‐ichi Kuroda 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2004,116(36):4867-4871
102.
The pH dependencies of electrochemomechanical deformation (ECMD) including the cyclic voltammetry and the expansion ratio in conducting polymers, polyaniline (PANI), and poly(o-methoxyaniline) film were studied to elucidate the mechanisms. It was found that the ECMD is governed by the conformational change of polymer structure as well as the insertion of bulky ions in the manner of comparable magnitude. Expansion ratios >20% in the ECMD were demonstrated for the thickness direction of PANI film. The results suggest that the magnitude of ECMD can be improved by choosing the preparation method of films. 相似文献
103.
Utilization of a metalloligand, ([Cu(2,4-pydca)2(H2O)].2Et3NH) (1) (2,4-pydca = pyridine-2,4-dicarboxylate), as a building unit provides a novel porous coordination polymer, ([ZnCu(2,4-pydca)2(H2O)3(DMF)].DMF)n (2), in which the Zn(II) ion at the node of the network acts as a linker and the Cu(II) ion in the channel wall is available for guest-coordination. 相似文献
104.
Quasi-solid-state dye-sensitized solar cells using room temperature molten salts and a low molecular weight gelator 总被引:1,自引:0,他引:1
Kubo W Kitamura T Hanabusa K Wada Y Yanagida S 《Chemical communications (Cambridge, England)》2002,(4):374-375
A dye-sensitized solar cell fabricated using the room temperature molten salt, 1-hexyl-3-methylimidazolium iodide, iodine and a low molecular weight gelator as a quasisolid-state electrolyte showed a 5.0% light-to-electricity conversion efficiency under AM 1.5 irradiation, and high-temperature stability. 相似文献
105.
Kaneda M Asaoka S Ikeda H Mori T Wada T Inoue Y 《Chemical communications (Cambridge, England)》2002,(12):1272-1273
A hydrostatic pressure of up to 750 MPa induced discontinuous changes in the enantiomeric excess of the (E)-isomer obtained in the enantio-differentiating photoisomerization of (Z)-cyclooctene and (Z,Z)-cycloocta-1,5-diene, sensitized by chiral benzene-1,2,4,5-tetracarboxylates; indicating a switching of the enantio-differentiation mechanism, which is attributable to dramatic conformational changes of chiral alkoxycarbonyl auxiliaries at a specific pressure. 相似文献
106.
107.
Mitsuda A Goto T Yoshimura K Zhang W Sato N Kosuge K Wada H 《Physical review letters》2002,88(13):137204
We investigated the magnetization of Yb0.8Y0.2InCu4 as a function of temperature down to 0.6 K, pressure up to 1.2 GPa, and magnetic field up to 9 T. The valence transition temperature of Yb0.8Y0.2InCu4 is lowered with applying pressure. At 0.8 GPa, collapse of the valence transition and ferromagnetic ordering occur almost simultaneously. The ferromagnetic phase at 1.2 GPa is characterized by a low Curie temperature of 1.7 K and an extremely small ordered moment of 0.05 micro(B) per Yb. Some effect of screening the ordered moment may play a key role in the ferromagnetism and the valence transition. 相似文献
108.
Bearden IG Beavis D Besliu C Blyakhman Y Budick B Bøggild H Chasman C Christensen CH Christiansen P Cibor J Debbe R Enger E Gaardhøje JJ Hagel K Hansen O Holm A Holme AK Ito H Jakobsen E Jipa A Jørdre JI Jundt F Jørgensen CE Karabowicz R Keutgen T Kim EJ Kozik T Larsen TM Lee JH Lee YK Løvhøiden G Majka Z Makeev A McBreen B Mikelsen M Murray M Natowitz J Nielsen BS Norris J Olchanski K Olness J Ouerdane D Płaneta R Rami F Ristea C Röhrich D Samset BH Sandberg D Sanders SJ Sheetz RA Staszel P 《Physical review letters》2002,88(20):202301
We present charged-particle multiplicities as a function of pseudorapidity and collision centrality for the 197Au+197Au reaction at square root[s(NN)] = 200 GeV. For the 5% most central events we obtain dN(ch)/deta/(eta = 0) = 625+/-55 and N(ch)/(-4.7< or =eta < or =4.7) = 4630 +/- 370, i.e., 14% and 21% increases, respectively, relative to square root[s(NN)] = 130 GeV collisions. Charged-particle production per pair of participant nucleons is found to increase from peripheral to central collisions around midrapidity. These results constrain current models of particle production at the highest RHIC energy. 相似文献
109.
Hashi K Shimizu T Goto A Kiyoshi T Matsumoto S Wada H Fujito T Hasegawa K Yoshikawa M Miki T Ito S Hamada M Hayashi S 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,156(2):318-321
We have developed a 920-MHz NMR system and performed the proton NMR measurement of H(2)O and ethylbenzene using the superconducting magnet operating at 21.6 T (920 MHz for proton), which is the highest field produced by a superconducting NMR magnet in the persistent mode. From the NMR measurements, it is verified that both homogeneity and stability of the magnet have a specification sufficient for a high resolution NMR. 相似文献
110.
A stereoselective synthesis of 11Z-retinal 2, which is the chromophore of visual pigment (rhodopsin), was accomplished from the beta-ionylideneacetaldehyde-tricarbonyliron complex 3. The Peterson reaction of 3 using ethyl trimethylsilylacetate smoothly proceeded to afford predominantly the Z-ester 6. Transformation of the Z-ester 6 to the methyl ketone 19, followed by the Emmons-Horner reaction of 19 with C2-cyanophosphonate, produced ethyl 11Z, 13E-retinonitrile-tricarbonyliron complex 21 as the only product. Decomplexation of 21 with CuCl2 and subsequent DIBAL reduction gave 11Z-retinal 2 in excellent yield. Mechanistic consideration of Z-selectivity in the Peterson reaction of the aldehyde-tricarbonyliron complex is also discussed. 相似文献