全文获取类型
收费全文 | 325篇 |
免费 | 16篇 |
专业分类
化学 | 285篇 |
晶体学 | 2篇 |
力学 | 1篇 |
数学 | 27篇 |
物理学 | 26篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 10篇 |
2019年 | 7篇 |
2018年 | 8篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 20篇 |
2012年 | 24篇 |
2011年 | 33篇 |
2010年 | 10篇 |
2009年 | 13篇 |
2008年 | 23篇 |
2007年 | 16篇 |
2006年 | 16篇 |
2005年 | 23篇 |
2004年 | 32篇 |
2003年 | 21篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1967年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有341条查询结果,搜索用时 46 毫秒
41.
Andreas Meissner Takayuki Kishi Yuka Fujisawa Yuto Murai Hiroyoshi Takamura Isao Kadota 《Tetrahedron letters》2018,59(51):4492-4495
A stereoselective formal total synthesis of enigmazole A, a marine macrolide isolated from Cinachyrella enigmatica, is described. Lewis acid mediated intramolecular allylation of an α-acetoxy ether, prepared from alcohol and carboxylic acid fragments was carried out to construct the methylene THP ring with high stereoselectivity. The late-stage macrolactonization of the corresponding seco-acid provided a known synthetic intermediate of enigmazole A. 相似文献
42.
A Smart Sensing Method for Object Identification Using Circularly Polarized Luminescence from Coordination‐Driven Self‐Assembly 下载免费PDF全文
Yuki Imai Yuka Nakano Prof. Tsuyoshi Kawai Dr. Junpei Yuasa 《Angewandte Chemie (International ed. in English)》2018,57(29):8973-8978
The potential use of circularly polarized luminescence for object identification in a sensor application is demonstrated. New luminescence probes using pyrene derivatives as sensor luminophores were developed. (R,R)‐Im2Py and (S,S)‐Im2Py contain two chiral imidazole moieties at 1,6‐positions through ethynyl spacers (angle between spacers ca. 180°). The probe molecules spontaneously self‐assemble into chiral stacks (P or M helicity) upon coordination to metal ions with tetrahedral coordination (Zn2+). The chiral probes display neither circular dichroism (CD) nor circularly polarized luminescence (CPL) without metal ions. However, (R,R)‐Im2Py and (S,S)‐Im2Py exhibit intense chiroptical activity (CD and CPL) upon self‐assembly with Zn2+ ions. (R,R)‐Im2Py and (S,S)‐Im2Py with chemical stimuli‐responsibility allow sensing using the CPL signal as detection output, enabling us to discriminate between a signal from the target analyte and that from non‐target species. 相似文献
43.
A new photoelectrochemical starch-O2 biofuel cell has been developed, consisting of chlorin-e6 (Chl-e6) adsorbed on a TiO2 layer onto an optical transparent conductive glass electrode as a photoanode, bilirubin oxidase (BOD)-modified electrode as a cathode, and a solution containing starch, glucoamylase, glucose dehydrogenase and NAD+ as fuel. The short-circuit photocurrent and the open-circuit photovoltage of this cell are 9.0 μA cm?2 and 530 mV, respectively. The maximum power, FF and \(\eta\) values are estimated to be 1.7 μW cm?2, 0.36 and 0.0017 %, respectively. Thus, this new type of the photochemical starch-O2 biofuel cell has been developed by using the visible light photosensitization of Chl-e6 on a TiO2 film photoanode. 相似文献
44.
Solar hydrogen production from cellulose biomass with enzymatic and artificial photosynthesis system
Yutaka?AmaoEmail author Yuka?Sakai Satomi?Takahara 《Research on Chemical Intermediates》2016,42(11):7753-7759
Bio-hydrogen gas production from renewable resources of timber waste, including cellulose, lignin, etc., is important in the environmental science and energy source development fields. A solar hydrogen production system by coupling waste paper including cellulose biomass with cellulase and glucose dehydrogenase (GDH), and hydrogen production with platinum nano-particle via the photoreduction of methylviologen (MV2+) using the visible light-harvesting function of Mg Chl-a, is developed. 相似文献
45.
Hideaki Oike Yuka Yoshioka Shinji Kobayashi Megumi Nakashima Yasuyuki Tezuka Eric J. Goethals 《Macromolecular rapid communications》2000,21(17):1185-1190
Mono‐, bis‐, and tris(trifluoromethanesulfonate ester)s ((triflate ester)s) were prepared by the reaction of benzyl alcohol ( 1 ), 1,4‐bis(hydroxymethyl)benzene ( 2 ) and 1,3,5‐tris(hydroxymethyl)benzene ( 3 ) with trifluoromethanesulfonic anhydride in the presence of 2,6‐di‐tert‐butylpyridine. These benzylic triflate esters were applied in‐situ for the living polymerization of tetrahydrofuran (THF). The subsequent end‐capping reaction with a suitable nucleophile proceeded quantitatively to produce mono, bi‐ and, in particular, novel trifunctional telechelic poly(THF)s, respectively. 相似文献
46.
Yuka Kobayashi 《Tetrahedron letters》2009,50(7):799-801
We have synthesized a tricyclic monoamine, (1S,4R)-(E)-7,3′-heptenylene-2,3:5,6-dibenzo-7-azabicyclo[2.2.1]heptane (1), by applying a ring-closing metathesis reaction in the key step of the synthetic route and by using preparative chiral HPLC for the separation. The X-ray crystallographic analysis of its salt with (1R)-camphor-10-sulfonic acid showed that the geometry and absolute configuration are (E) and (1S,4R), respectively. The theoretical calculations revealed that the inversion of the nitrogen atom at the 7-position of (1S,4R)-(E)-1 thus isolated takes place through a very slow process and that the configuration of the N(7) is highly biased to (R), indicating that (1S,4R)-(E)-1 is a thermodynamically controlled N-pseudo-chirotopic compound ((1S,4R,7R): (1S,4R,7S) = 99.68:0.32 at 120 °C). 相似文献
47.
Yuka Naito 《Mathematical Methods in the Applied Sciences》2009,32(13):1609-1637
This paper is concerned with the thermoelastic plate equations in a domain Ω: subject to the boundary condition: u|=Dνu|=θ|=0 and initial condition: (u, ut, θ)|t=0=(u0, v0, θ0). Here, Ω is a bounded domain in ?n(n≧2). We assume that the boundary ?Ω of Ω is a C4 hypersurface. We obtain an Lp–Lq maximal regularity theorem. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
48.
Two significantly different conformations were observed in crystal of 1, which form an unsymmetrical molecular dimer governed by cation-π interactions between a pyridinium cation and a phenyl ring, whereas compound 2 forms a head-to-tail type of dimer. 相似文献
49.
Yuka Akimura Toshiki Maruyama Naotaka Yoshinaga Satoshi Chiba 《Acta Physica Hungarica A》2006,27(2-3):355-358
We study the hadron-quark phase transition in a molecular dynamics (MD) of quark degrees of freedom. The hadron state at low density and temperature, and the deconfined quark state at high density and temperature are observed in our model. We investigate the equations of state and draw the phase diagram at wide baryon density and temperature range. We also discuss the transport property, e.g. viscosity, of $q\bar q$ matter. It is found that the ratio of the shear viscosity to the entropy density is less than one for quark matter. 相似文献
50.
Yuka Fujiki Shogo Mizutaka Kousuke Yakubo 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(7):126
Fractal scale-free networks are empirically known to exhibit disassortative degree mixing. It is, however, not obvious whether a negative degree correlation between nearest neighbor nodes makes a scale-free network fractal. Here we examine the possibility that disassortativity in complex networks is the origin of fractality. To this end, maximally disassortative (MD) networks are prepared by rewiring edges while keeping the degree sequence of an initial uncorrelated scale-free network. We show that there are many MD networks with different topologies if the degree sequence is the same with that of the (u,v)-flower but most of them are not fractal. These results demonstrate that disassortativity does not cause the fractal property of networks. In addition, we suggest that fractality of scale-free networks requires a long-range repulsive correlation, in the sense of the shortest path distance, in similar degrees. 相似文献