全文获取类型
收费全文 | 3066篇 |
免费 | 130篇 |
国内免费 | 9篇 |
专业分类
化学 | 2518篇 |
晶体学 | 22篇 |
力学 | 21篇 |
数学 | 165篇 |
物理学 | 479篇 |
出版年
2023年 | 27篇 |
2022年 | 13篇 |
2021年 | 42篇 |
2020年 | 71篇 |
2019年 | 61篇 |
2018年 | 20篇 |
2017年 | 15篇 |
2016年 | 69篇 |
2015年 | 67篇 |
2014年 | 80篇 |
2013年 | 170篇 |
2012年 | 184篇 |
2011年 | 203篇 |
2010年 | 112篇 |
2009年 | 93篇 |
2008年 | 208篇 |
2007年 | 201篇 |
2006年 | 206篇 |
2005年 | 212篇 |
2004年 | 192篇 |
2003年 | 142篇 |
2002年 | 147篇 |
2001年 | 43篇 |
2000年 | 46篇 |
1999年 | 48篇 |
1998年 | 40篇 |
1997年 | 44篇 |
1996年 | 30篇 |
1995年 | 25篇 |
1994年 | 19篇 |
1993年 | 18篇 |
1992年 | 19篇 |
1991年 | 16篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 12篇 |
1985年 | 32篇 |
1984年 | 28篇 |
1983年 | 16篇 |
1982年 | 23篇 |
1981年 | 22篇 |
1980年 | 19篇 |
1979年 | 21篇 |
1978年 | 21篇 |
1977年 | 16篇 |
1976年 | 17篇 |
1975年 | 11篇 |
1974年 | 10篇 |
1973年 | 9篇 |
1969年 | 7篇 |
排序方式: 共有3205条查询结果,搜索用时 15 毫秒
991.
992.
Dr. Ki-Young Lee Dr. Zhenhao Fang Dr. Masahiro Enomoto Dr. Genevieve Gasmi-Seabrook Le Zheng Prof. Shohei Koide Prof. Mitsuhiko Ikura Dr. Christopher B. Marshall 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(27):11130-11138
KRAS homo-dimerization has been implicated in the activation of RAF kinases, however, the mechanism and structural basis remain elusive. We developed a system to study KRAS dimerization on nanodiscs using paramagnetic relaxation enhancement (PRE) NMR spectroscopy, and determined distinct structures of membrane-anchored KRAS dimers in the active GTP- and inactive GDP-loaded states. Both dimerize through an α4–α5 interface, but the relative orientation of the protomers and their contacts differ substantially. Dimerization of KRAS-GTP, stabilized by electrostatic interactions between R135 and E168, favors an orientation on the membrane that promotes accessibility of the effector-binding site. Remarkably, “cross”-dimerization between GTP- and GDP-bound KRAS molecules is unfavorable. These models provide a platform to elucidate the structural basis of RAF activation by RAS and to develop inhibitors that can disrupt the KRAS dimerization. The methodology is applicable to many other farnesylated small GTPases. 相似文献
993.
994.
Hoang The Ban Masahiro Shigeta Tsutomu Nagamune Mitsugu Uejima 《Journal of polymer science. Part A, Polymer chemistry》2013,51(21):4584-4591
An efficient and environmentally benign synthetic method for the production of the stabilized cyclo‐olefin copolymer latexes and their carbon nanotube composite nanoparticles has been developed using an emulsion ring opening metathesis copolymerization catalyzed by the 2nd generation Grubbs catalyst in aqueous solution. Homopolymerizations of norbornene (NB) and dicyclopentadiene (DCPD) in aqueous solution yield unstable polymer latexes in combination with a large amount of their flocculation fractions. Copolymerizations of NB or DCPD with a selected liquid cyclo‐olefin comonomer dramatically improve not only the colloidal stability of the copolymer latexes but also the thermal stability of the copolymer nanoparticles. The liquid cyclo‐olefin comonomer plays a double role as a liquefied agent for the solid NB and DCPD monomers before the emulsification treatment, and a reactive comonomer itself to control entirely the copolymerization system. The as‐prepared cyclo‐olefin copolymer latexes exhibit an exceptionally high compatibility with a well‐dispersed carbon nanotube (CNT) in aqueous solution due to strong π–π interactions between the graphitic surfaces of the CNT with the C‐C double bonds located on the cyclo‐olefin copolymer main chains. Accordingly, a binary blending of these two well‐dispersed colloidal systems in aqueous solution led to the fabrication, for the first time, of the highly electrical conductive cyclo‐olefin copolymer/CNT composite nanoparticles. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4584–4591 相似文献
995.
996.
Dr. Masahiro Yamamoto Dr. Ryuhei Nakamura Dr. Takafumi Kasaya Dr. Hidenori Kumagai Dr. Katsuhiko Suzuki Dr. Ken Takai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):5819-5822
Deep-sea hydrothermal vents discharge abundant reductive energy into oxidative seawater. Herein, we demonstrated that in situ measurements of redox potentials on the surfaces of active hydrothermal mineral deposits were more negative than the surrounding seawater potential, driving electrical current generation. We also demonstrated that negative potentials in the surface of minerals were widespread in the hydrothermal fields, regardless of the proximity to hydrothermal fluid discharges. Lab experiments verified that the negative potential of the mineral surface was induced by a distant electron transfer from the hydrothermal fluid through the metallic and catalytic properties of minerals. These results indicate that electric current is spontaneously and widely generated in natural mineral deposits in deep-sea hydrothermal fields. Our discovery provides important insights into the microbial communities that are supported by extracellular electron transfer and the prebiotic chemical and metabolic evolution of the ocean hydrothermal systems. 相似文献
997.
998.
Shuji Ioka Dr. Tsuyoshi Saitoh Dr. Satoshi Iwano Prof. Dr. Koji Suzuki Dr. Shojiro A. Maki Prof. Dr. Atsushi Miyawaki Prof. Dr. Masaya Imoto Prof. Dr. Shigeru Nishiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9330-9337
Five new firefly luciferin ( 1 ) analogues were synthesized and their light emission properties were examined. Modifications of the thiazoline moiety in 1 were employed to produce analogues containing acyclic amino acid side chains ( 2 – 4 ) and heterocyclic rings derived from amino acids ( 5 and 6 ) linked to the benzothiazole moiety. Although methyl esters of all of the synthetic derivatives exhibited chemiluminescence activity, only carboluciferin ( 6 ), possessing a pyrroline‐substituted benzothiazole structure, had bioluminescence (BL) activity (λmax=547 nm). Results of bioluminescence studies with AMP‐carboluciferin (AMP=adenosine monophosphate) and AMP‐firefly luciferin showed that the nature of the thiazoline mimicking moiety affected the adenylation step of the luciferin–luciferase reaction required for production of potent BL. In addition, BL of 6 in living mice differed from that of 1 in that its luminescence decay rate was slower. 相似文献
999.
Jing Kong Wei Liu Fenglong Wang Xinzhen Wang Liqiang Luan Jiurong Liu Yuan Wang Zijun Zhang Masahiro Itoh Ken-ichi Machida 《Journal of solid state chemistry》2011,184(11):2994-3001
Monodispersed Ni flower-like architectures with size of 1–2 μm were synthesized through a facile solvent-thermal process in 1,2-propanediol solution in the presence of polyethylene glycol (PEG) and sodium alkali for electromagnetic absorption application. The Ni architectures are composed of nanoflakes, which assemble to form three dimensional flower-like structure, and the thickness of nanoflakes is about 10–40 nm. A possible formation mechanism for Ni flower-like architectures was proposed and it was confirmed by the control experiments. The Ni architectures exhibited a saturation magnetization (Ms) of 47.7 emu/g and a large coercivity (Hcj) of 332.3 Oe. The epoxy resin composites with 20 vol% Ni sample provided good electromagnetic wave absorption performance (reflection loss <−20 dB) in the range of 2.8–6.3 GHz over absorber thickness of 2.6–5.0 mm. 相似文献
1000.