全文获取类型
收费全文 | 812篇 |
免费 | 26篇 |
国内免费 | 4篇 |
专业分类
化学 | 529篇 |
晶体学 | 3篇 |
力学 | 13篇 |
数学 | 67篇 |
物理学 | 230篇 |
出版年
2023年 | 5篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 19篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 22篇 |
2015年 | 10篇 |
2014年 | 19篇 |
2013年 | 42篇 |
2012年 | 38篇 |
2011年 | 33篇 |
2010年 | 29篇 |
2009年 | 23篇 |
2008年 | 50篇 |
2007年 | 55篇 |
2006年 | 44篇 |
2005年 | 34篇 |
2004年 | 51篇 |
2003年 | 22篇 |
2002年 | 26篇 |
2001年 | 28篇 |
2000年 | 27篇 |
1999年 | 22篇 |
1998年 | 13篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 13篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有842条查询结果,搜索用时 265 毫秒
801.
K. Yoshino M. Ozaki K. Nakao H. Taniguchi N. Yamasaki K. Satoh 《Liquid crystals》2013,40(4):1203-1211
The magnitude and direction of the spontaneous polarization in most ferroelectric liquid crystals have been confirmed to be determined by the location and magnitude of the bond moment around the chiral carbon and the core. In compounds with several bond moments their relative orientation is very important for obtaining a large spontaneous polarization. Compounds with benzene rings in the core substituted with OH also have a large spontaneous polarization, perhaps due to the formation of hydrogen bonds. Reversal of the direction of the spontaneous polarization with temperature has been found for EFPPOPB. This anomalous behaviour has been explained tentatively in terms of a conformation change due to the existence of a flexible -CH2- unit between the chiral carbon and the dipole moment. 相似文献
802.
A. Hirashima K. Shinkai E. Kuwano E. Taniguchi M. Eto 《SAR and QSAR in environmental research》2013,24(1):45-54
Abstract The quantitative structure-activity relationship of 39 octopamine (OA) agonists and 12 antagonists against the thoracic nerve cord of the migratory locust, Locusta migratoria L. was analyzed using atom based rigid fit method or flexible fitting offered by PowerFit 1.0 from MicroSimulation. For OA agonists, the more similar to reference compound NC (24) the structure of test compound, the higher the activity, whereas for OA antagonists it was not the case. Antagonists may not interact with the same part of the membrane with which the agonists interact. Taken the part of the membrane with which the agonist interacts as the true receptor, the antagonist may well interact with an area surrounding the receptor including the ionophore. 相似文献
803.
Guoyang Guan Shuhei Fukuoka Satoshi Yamashita Takashi Yamamoto Hiromi Taniguchi Yasuhiro Nakazawa 《Journal of Thermal Analysis and Calorimetry》2013,113(3):1197-1201
Thermodynamic investigation using the relaxation calorimetry technique and the microchip calorimetry technique is performed to clarify low-temperature behaviors of a radical cation salt consisting of a donor molecule of bispropylenedithiotetrathiafulvalene (BPDT-TTF) and a linear anion of ${{\text{ICl}}_{2}^{-}}$ ICl 2 ? . This compound has a layered structure similar to numerous BEDT-TTF compounds. The donor molecules form a dimerized arrangement in the layer. Temperature dependence of heat capacity obtained by the relaxation technique shows a broad hump structure around 20–25 K corresponding to the temperature where the magnetic susceptibility shows a drastic decrease due to the formation of the singlet spin state. The microchip calorimetry technique detected a step-like anomaly around 23 K in the temperature dependence of C p T ?1 of which entropy is evaluated as only few % of Rln2 corresponding to the full entropy of localized π-electrons located on each dimer unit. The negligibly small T-linear term in the low-temperature heat capacity and absence of magnetic fields dependence below 3.2 K predict opening of rigid gap structure in the spin excitations, which is consistent with a spin-singlet formation due to the formation of spin-Peierls type ordering or charge ordering state. 相似文献
804.
Noboru Taniguchi 《Separation & Purification Reviews》2013,42(2):247-299
The term “mucopolysaccharides” was originally introduced by Meyer to describe “hexosamine-containing heteropolysaccharides of animal origin occurring in a pure state or as protein salts”. Many of the names originally assigned to the mucopolysaccharides have since been revised in an effort to systematize the nomenclature (Table 1). Jeanloz2 in 1960 proposed the term “glycosaminoglycuronoglycans” in place of mucopolysaccharides as in most cases they are composed of amino sugars (glycosamino-) and uronic acids (glycurono-) joined in long chains(-glycans). For the sake of simplicity, the term “glycosaminoglycans” is getting acceptance in place of the rather lengthy term “glycosaminoglycuronoglycans” as well as the old and perhaps more familiar term “mucopolysaccharides”. As a matter of convenience, the term “polysaccharides” will be frequently used here, instead of glycosaminoglycans. 相似文献
805.
Yibo Wang Siqi Jiang Jingkuan Xiao Xiaofan Cai Di Zhang Ping Wang Guodong Ma Yaqing Han Jiabei Huang Kenji Watanabe Takashi Taniguchi Yanfeng Guo Lei Wang Alexander S. Mayorov Geliang Yu 《Frontiers of Physics》2022,17(4):43504
Van der Waals (vdW) assembly of two-dimensional materials has long been recognized as a powerful tool for creating unique systems with properties that cannot be found in natural compounds [Nature 499, 419 (2013)]. However, among the variety of vdW heterostructures and their various properties, only a few have revealed metallic and ferroelectric behaviour signatures [Sci. Adv. 5, eaax5080 (2019); Nature560, 336 (2018)]. Here we show ferroelectric semimetal made of double-gated double-layer graphene separated by an atomically thin crystal of hexagonal boron nitride. The structure demonstrates high room temperature mobility of the order of 10 m2·V−1·s−1 and exhibits ambipolar switching in response to the external electric field. The observed hysteresis is reversible and persists above room temperature. Our fabrication method expands the family of ferroelectric vdW compounds and offers a promising route for developing novel phase-changing devices. A possible microscopic model of ferroelectricity is discussed. 相似文献
806.
Attenuation of the Aggregation and Neurotoxicity of Amyloid‐β Peptides by Catalytic Photooxygenation 下载免费PDF全文
Dr. Atsuhiko Taniguchi Dr. Daisuke Sasaki Azusa Shiohara Prof. Takeshi Iwatsubo Dr. Taisuke Tomita Dr. Youhei Sohma Prof. Motomu Kanai 《Angewandte Chemie (International ed. in English)》2014,53(5):1382-1385
Alzheimer’s disease (AD), a progressive severe neurodegenerative disorder, is currently incurable, despite intensive efforts worldwide. Herein, we demonstrate that catalytic oxygenation of amyloid‐β peptides (Aβ) might be an effective approach to treat AD. Aβ1–42 was oxygenated under physiologically‐relevant conditions (pH 7.4, 37 °C) using a riboflavin catalyst and visible light irradiation, with modifications at the Tyr10, His13, His14, and Met35 residues. The oxygenated Aβ1–42 exhibited considerably lower aggregation potency and neurotoxicity compared with native Aβ. Photooxygenation of Aβ can be performed even in the presence of cells, by using a selective flavin catalyst attached to an Aβ‐binding peptide; the Aβ cytotoxicity was attenuated in this case as well. Furthermore, oxygenated Aβ1–42 inhibited the aggregation and cytotoxicity of native Aβ. 相似文献
807.
Haik Chosrowjan Seiji Taniguchi Noboru Mataga Fumio Tanaka Daisuke Todoroki Masaya Kitamura 《Chemical physics letters》2008,462(1-3):121-124
Ultrafast fluorescence dynamics of FMN in FMN-binding protein (FMN-bp), and its mutated proteins, W32Y and W32A, were investigated by the fluorescence up-conversion method. Fluorescence lifetimes were 167 fs (96%) and 1.5 ps (4%) in wild-type FMN-bp (WT), and 3.4 ps (23%), 18.2 ps (74%), and 96 ps (3%) at 530 nm in W32Y, and 30.1 ps in W32A. The fluorescence lifetime of W32A, in which Trp-32 was absent, was about 140 times longer than that of WT. Tyr-32 in W32Y was not so effective quencher as Trp-32 in WT. This was explained in terms of different ionization potentials of quenchers and average donor–acceptor distances in the protein. 相似文献
808.
Taniguchi T Fukuba TA Nakatsuka S Hayase S Kawatsura M Uno H Itoh T 《The Journal of organic chemistry》2008,73(10):3875-3884
Candida antarctica lipase B (CAL-B) is one the most frequently used enzymes in organic synthesis for the preparation of optically active alcohols. However, it has not been used for the optical resolution of (+/-)-2,2'-binaphthol. We established an efficient linker-oriented design of 2,2'-binaphthol derivatives that is appropriate for optical resolution using CAL-B-catalyzed hydrolysis reaction. Methyl 4-(1-(6-bromo-2-methoxymethoxynaphthalen-1-yl)-6-bromonaphthalen-2-yloxy)butanoate was hydrolyzed by CAL-B to afford a corresponding acid with excellent enantioselectivity ( E > 200). Two types of optically active binaphthol derivatives, 1-(2-hydroxy-6-(naphthalen-1-yl)naphthalen-1-yl)-6-(naphthalen-1-yl)naphthalen-2-ol and 6-butyl-1-(6-butyl-2-hydroxynaphthalen-1-yl)naphthalen-2-ol, were prepared by this chemo-enzymatic reaction protocol and were used as chiral templates for symmetric reactions. 相似文献
809.
Tsuyoshi Taniguchi 《Tetrahedron》2008,64(37):8773-8779
A total synthesis of (±)-stemonamide and (±)-isostemonamide has been achieved by using a radical cascade that involves two endo-selective cyclizations. (±)-Stemonamine and (±)-isostemonamine are synthesized by chemoselective reduction of (±)-stemonamide and (±)-isostemonamide, respectively. 相似文献
810.
Poly(amidoamine) (PAMAM) dendrimers showed high CO2 separation properties and were successfully immobilized in a poly(ethylene glycol) (PEG) network upon photopolymerization of PEG dimethacrylate. The PAMAM dendrimer incorporation ratio was readily controlled, and a stable self-standing membrane containing up to 75 wt.% PAMAM dendrimer was obtained. The CO2 separation properties over smaller H2 were investigated by changing the PAMAM dendrimer content or generation and CO2 partial pressure (ΔPCO2) under atmospheric conditions. Especially, a polymeric membrane containing 50 wt.% PAMAM dendrimer (0th generation) exhibited an excellent CO2/H2 selectivity of 500 with CO2 permeability of 2.74 × 10−14 m3(STP)m/(m2 s Pa) or 3.65 × 103 barrer (1 barrer = 7.5 × 10−18 m3(STP)m/(m2 s Pa)) when a mixture gas (CO2/H2: 5/95 by vol.) was fed at 25 °C and 100 kPa with 80% relative humidity. This polymeric materials are promising for a novel CO2 separation membrane. 相似文献