全文获取类型
收费全文 | 661篇 |
免费 | 42篇 |
国内免费 | 3篇 |
专业分类
化学 | 571篇 |
晶体学 | 2篇 |
力学 | 3篇 |
数学 | 19篇 |
物理学 | 111篇 |
出版年
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 10篇 |
2020年 | 11篇 |
2019年 | 23篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 25篇 |
2015年 | 16篇 |
2014年 | 24篇 |
2013年 | 37篇 |
2012年 | 37篇 |
2011年 | 61篇 |
2010年 | 22篇 |
2009年 | 25篇 |
2008年 | 34篇 |
2007年 | 41篇 |
2006年 | 33篇 |
2005年 | 43篇 |
2004年 | 33篇 |
2003年 | 21篇 |
2002年 | 28篇 |
2001年 | 18篇 |
2000年 | 22篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 13篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1975年 | 2篇 |
1973年 | 5篇 |
1968年 | 3篇 |
1966年 | 2篇 |
1965年 | 2篇 |
排序方式: 共有706条查询结果,搜索用时 15 毫秒
121.
Extended pi-conjugated molecules are interesting materials that have been studied theoretically and experimentally with applications to conducting nanowire, memory, and diode in mind. Chemical understanding of electron transport properties in molecular junctions, in which two electrodes have weak contact with a pi-conjugated molecule, is presented in terms of the orbital concept. The phase and amplitude of the HOMO and LUMO of pi-conjugated molecules determine essential properties of the electron transport in them. The derived rule allows us to predict single molecules' essential transport properties, which significantly depend on the type of connection between a molecule and electrodes. Qualitative predictions based on frontier orbital analysis about the site-dependent electron transport in naphthalene, phenanthrene, and anthracene are compared with density functional theory calculations for the molecular junctions of their dithiolate derivatives, in which two gold electrodes have strong contact with a molecule through two Au-S bonds. 相似文献
122.
Asymmetric Induction by a Nitrogen 14N/15N Isotopomer in Conjunction with Asymmetric Autocatalysis 下载免费PDF全文
Dr. Arimasa Matsumoto Hanae Ozaki Shunya Harada Kyohei Tada Tomohiro Ayugase Hitomi Ozawa Prof. Dr. Tsuneomi Kawasaki Prof. Dr. Kenso Soai 《Angewandte Chemie (International ed. in English)》2016,55(49):15246-15249
Chirality arising from isotope substitution, especially with atoms heavier than the hydrogen isotopes, is usually not considered a source of chirality in a chemical reaction. An N2,N2,N3,N3‐tetramethyl‐2,3‐butanediamine containing nitrogen (14N/15N) isotope chirality was synthesized and it was revealed that this isotopically chiral diamine compound acts as a chiral initiator for asymmetric autocatalysis. 相似文献
123.
Size‐Dependence of the Activity of Gold Nanoparticle‐Loaded Titanium(IV) Oxide Plasmonic Photocatalyst for Water Oxidation 下载免费PDF全文
Miwako Teranishi Masataka Wada Dr. Shin‐ichi Naya Prof. Hiroaki Tada 《Chemphyschem》2016,17(18):2813-2817
Mesoporous TiO2 nanocrystalline film was formed on fluorine‐doped tin oxide electrode (TiO2/FTO) and gold nanoparticles (NPs) of different sizes were loaded onto the surface with the loading amount kept constant (Au/TiO2/FTO). Visible‐light irradiation (λ>430 nm) of the Au/TiO2/FTO photoanode in a photoelectrochemical cell with the structure of photoanode|0.1 m NaClO4 aqueous solution|Ag/AgCl (reference electrode)|glassy carbon (cathode) leads to the oxidation of water to oxygen (O2). We show that the visible‐light activity of the Au/TiO2/FTO anode increases with a decrease in Au particle size (d) at 2.9≤d≤11.9 nm due to the enhancement of the charge separation and increasing photoelectrocatalytic activity. 相似文献
124.
Imaging of Oxygen Diffusion in Individual Platinum/Ce2Zr2Ox Catalyst Particles During Oxygen Storage and Release 下载免费PDF全文
Dr. Hirosuke Matsui Dr. Nozomu Ishiguro Kaori Enomoto Dr. Oki Sekizawa Prof. Dr. Tomoya Uruga Prof. Dr. Mizuki Tada 《Angewandte Chemie (International ed. in English)》2016,55(39):12022-12025
The spatial distribution of Ce3+ and Ce4+ in each particle of Ce2Zr2Ox in a three‐way conversion catalyst system was successfully imaged during an oxygen storage/release cycle by scanning X‐ray absorption fine structure (XAFS) using hard X‐ray nanobeams. For the first time, nano‐XAFS imaging visualized and identified the modes of non‐uniform oxygen diffusion from the interface of Pt catalyst and Ce2Zr2Ox support and the active parts in individual catalyst particles. 相似文献
125.
[structure: see text] The addition of oligothiophene into a dendritic structure causes a self-association behavior by intermolecular pi-pi interactions in a solution and in a solid state. Increasing the generation of the dendritic structure gives not only a high association constant but also sufficient field-effect hole mobility, which indicates that the charge-transporting passes are formed by the strong pi-pi interactions. 相似文献
126.
Since 1985, AOAC Method 985.29 has been globally adopted as a standard method for determination of total dietary fiber in foods. Nevertheless, an aspect of AOAC Method 985.29 that needs to be improved is the laborious process to treat 3 enzymes separately at their individual proper pH, which is quite time-consuming. Several examinations have been carried out to resolve this problem. The characteristics of newly developed thermostable alpha-amylase, neutral protease, and amyloglucosidase were evaluated based on the pH-activity profile and the property of starch hydrolysis in comparison with those of the conventional enzyme reagents. These 3 developed enzymes were found to work under the same pH condition and to accomplish sufficient digestion for the typical 3 starches: soluble starch, corn starch, and wheat starch. The experimental results revealed that the dietary fiber determination in foods could be performed without pH adjustment in the enzymatic digestion process. The modified method will be greatly helpful in determining the total dietary fiber contents in food materials with less laborious work and with an accuracy equivalent to that of AOAC Method 985.29. 相似文献
127.
Vision begins when light is absorbed by visual pigments. It is commonly believed that the absorption spectra of visual pigments are modulated by interactions between the retinal and amino acids within or near 4.5 angstroms of the retinal in the transmembrane (TM) segments. However, this dogma has not been rigorously tested. In this study, we show that the retinal-opsin interactions extend well beyond the retinal binding pocket. We found that, although it is positioned outside of TM segments, the C-terminus of the rhodopsin in the rockfish longspine thornyhead (Sebastolobus altivelis) modulates its lambda(max) by interacting mainly with the last TM segment. Our results illustrate how amino acids in the C-terminus are likely to interact with the retinal. We anticipate our analyses to be a starting point for viewing the spectral tuning of visual pigments as interactions between the retinal and key amino acids that are distributed throughout the entire pigment. 相似文献
128.
Yamada K Mukaihata N Kawahara T Tada H 《Langmuir : the ACS journal of surfaces and colloids》2007,23(16):8593-8596
The synergy of an anodic-biased alpha-Fe2O3 film and a cationic surfactant molecular assembly leads to a high visible light induced activity for 2-naphthol oxidation and high stability. An abrupt increase in the photocatalytic activity at a surfactant concentration of ca. 0.2 mmol dm(-3) results from the adsolubilization of 2-naphthol into the hydrophobic nanospace of the surfactant bilayer formed on the alpha-Fe2O3 surface. Also, the surfactant bilayer provides sustainable photocurrent during the reaction. 相似文献
129.
M. Tada H. Yokoyama Y. Toyoda H. Ohya T. Ito T. Ogata 《Applied magnetic resonance》2000,18(4):575-582
Three kinds of surface-coil-type resonators (SCRs) operating at 720 MHz were fabricated for in vivo temporal electron spin resonance (ESR) measurements. The inner diameter of the singleturn coil of the SCRs was 3, 4, or 10 mm. ResonatorQ increases and the detection limit decreases with coil diameter. The distance across which the microwave magnetic field can penetrate in the direction facing to the coil was about the same (about 2 mm) for all SCRs. In vivo kinetic studies of intravenously injected 4-hydroxy-2,2,6,6-tetramethylpiperidin-l-oxyl (TEMPOL) were performed at the liver, kidney, stomach, rectum, vein, and skin of rats with SCRs suited to the target areas. The halflife of TEMPOL was estimated from the exponential decay of the ESR signal intensity (the peak-to-peak height). Different sites in the rat showed apparent differences in the half-life of TEMPOL. This suggests that the apparent differences in the reducing ability of TEMPOL are related to the organ or tissue where measurement is taken because no excretion of TEMPOL was observed. 相似文献
130.
Chifei Wu Tada‐Aki Yamagishi Yoshiaki Nakamoto Shin‐Ichiro Ishida Saburo Kubota Koh‐Hei Nitta 《Journal of Polymer Science.Polymer Physics》2000,38(11):1496-1503
The viscoelastic properties and stabilities of those properties of organic hybrids consisting of chlorinated polyethylene (CPE) and tetrakis[methylene‐3‐(3‐5‐di‐tert‐butyl‐4‐hydroxy phenyl)propionyloxy]methane (AO‐60) and triethylene glycol bis[3‐(3‐tert‐butyl‐4‐hydroxy‐5‐methyl phenyl)propionyloxy] (AO‐70) were investigated. The CPE/AO‐70 hybrids show only one transition, whereas for the CPE/AO‐60 hybrids, one novel relaxation appears above the glass‐transition temperature of CPE. This relaxation on the higher temperature side in the mechanical spectrum for CPE/AO‐60 is associated with the appearance of the AO‐60‐rich phase. Furthermore, the stabilities of the viscoelastic properties and microstructures of the organic hybrids consisting of CPE and multifunctional hindered phenols are dominated by the strength of the intermolecular interaction between CPE and phenols and the conformations of the middle skeletal parts of hindered phenols. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1496–1503, 2000 相似文献