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661.
662.
Kyu Hyung Park Pyosang Kim Woojae Kim Hideyuki Shimizu Minwoo Han Eunji Sim Masahiko Iyoda Dongho Kim 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(43):12902-12906
Excited‐state dynamic planarization processes play a crucial role in determining exciton size in cyclic systems, as reported for π‐conjugated linear oligomers. Herein, we report time‐resolved fluorescence spectra and molecular dynamics simulations of π‐conjugated cyclic oligothiophenes in which the number of subunits was chosen to show the size‐dependent dynamic planarization in the vicinity of a ring‐to‐linear behavioral turning point. Analyses on the evolution of the total fluorescence intensity and the ratio between 0–1 to 0–0 vibronic bands suggest that excitons formed in a cyclic oligothiophene composed of six subunits fully delocalize over the cyclic carbon backbone, whereas those formed in larger systems fail to achieve complete delocalization. With the aid of molecular dynamics simulations, it is shown that distorted structures unfavorable for efficient exciton delocalization are more easily populated as the size of the cyclic system increases. 相似文献
663.
High‐Power Electrochemical Energy Storage System Employing Stable Radical Pseudocapacitors 下载免费PDF全文
Hitoshi Maruyama Dr. Hideyuki Nakano Dr. Masaaki Nakamoto Prof. Dr. Akira Sekiguchi 《Angewandte Chemie (International ed. in English)》2014,53(5):1324-1328
The development of electrical energy storage devices that can operate at high charge and discharge rates is fundamentally important, however although electrochemical capacitors (ECs) can charge and discharge at high rates, their electrochemical storage capacity remains an order of magnitude lower than that of conventional lithium‐ion batteries. Novel pseudocapasitors are developed, based on the stable persilyl‐susbtituted free radicals of the heavy group 14 elements, (tBu2MeSi)3E. [E=Si ( 1 ), Ge ( 2 ), and Sn ( 3 )], as anode materials for energy storage system. Such systems showed a remarkable cycle stability without significant loss of power density, in comparison with similar characteristics of the known organic radical batteries, the dual carbon cell, and the electrochemical capacitor. Particularly important is that these novel electrochemical energy storage systems employing stable heavy group 14 element radicals are lithium‐free. The electrochemical properties and structures of the reduced and oxidized species were studied by the cyclic voltammetry (CV), electron paramagnetic resonance (EPR) spectroscopy, and X‐ray diffraction (XRD). 相似文献
664.
Cobalt Phenanthroline–Indole Macrocycles as Highly Active Electrocatalysts for Oxygen Reduction 下载免费PDF全文
Martin Quernheim Dr. Haiwei Liang Dr. Qi Su Prof. Dr. Martin Baumgarten Dr. Nobuyoshi Koshino Dr. Hideyuki Higashimura Prof. Dr. Klaus Müllen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14178-14183
The replacement of scarce and expensive platinum species poses a challenge in fuel‐cell development. The design and synthesis of a novel type of CoII–N4 macrocyclic complex, [CoN4], based on the phenanthroline–indole macrocyclic ligand (PIM) is reported. This unique ligand allows the formation of mono‐ and dinuclear complexes with defined active sites that facilitate the direct four‐electron reduction of oxygen. Electrochemical measurements revealed that the [CoN4]/C (20 wt %) catalysts have a high activity and long‐term stability for the oxygen‐reduction reaction (ORR) under alkaline conditions, similar to the Pt/C catalyst. These structurally well‐defined complexes represent a nonprecious alternative to platinum species for future fuel‐cell applications. 相似文献
665.
Frontispiece: Cobalt Phenanthroline–Indole Macrocycles as Highly Active Electrocatalysts for Oxygen Reduction 下载免费PDF全文
666.
Katsuhiro Shirono Masanori Shiro Hideyuki Tanaka Kensei Ehara 《Accreditation and quality assurance》2014,19(5):377-389
The gravimetric method specified by ISO 8655-6 is a standard method for calibrating piston pipettes (micropipettes). The quality of the calibration can be assessed by uncertainty evaluation, the procedure for which is described in ISO/Technical Report (TR) 20461. However, the existence of “method uncertainty” due to ambiguity in the calibration operation, which is not described in the TR, has been found in various experiments, such as the interlaboratory comparison of CCM.FF-K4.2.2011. In this report, the “method standard uncertainty” is quantified as exp(?4.51 + 0.36 ln(V nom/μL) + 0.05{ln(V nom/μL)}2) μL for a nominal volume, V nom, in the range from 2 μL to 10000 μL. Furthermore, the reported values in an interlaboratory comparison are confirmed to be consistent using the quantified method standard uncertainty. 相似文献
667.
Prof. Hoon Hyun Eric A. Owens Dr. Hideyuki Wada Andrew Levitz GwangLi Park Prof. Min Ho Park Prof. John V. Frangioni Prof. Maged Henary Prof. Hak Soo Choi 《Angewandte Chemie (International ed. in English)》2015,54(30):8648-8652
A novel class of near‐infrared fluorescent contrast agents was developed. These agents target cartilage with high specificity and this property is inherent to the chemical structure of the fluorophore. After a single low‐dose intravenous injection and a clearance time of approximately 4 h, these agents bind to all three major types of cartilage (hyaline, elastic, and fibrocartilage) and perform equally well across species. Analysis of the chemical structure similarities revealed a potential pharmacophore for cartilage targeting. Our results lay the foundation for future improvements in tissue engineering, joint surgery, and cartilage‐specific drug development. 相似文献
668.
Enzymatic Synthesis of a DNA Triblock Copolymer that is Composed of Natural and Unnatural Nucleotides 下载免费PDF全文
Prof. Hideyuki Mitomo Yukie Watanabe Prof. Yasutaka Matsuo Prof. Kenichi Niikura Prof. Kuniharu Ijiro 《化学:亚洲杂志》2015,10(2):455-460
DNA molecules have come under the spotlight as potential templates for the fabrication of nanoscale products, such as molecular‐scale electronic or photonic devices. Herein, we report an enhanced approach for the synthesis of oligoblock copolymer‐type DNA by using the Klenow fragment exonuclease minus of E. coli DNA polymerase I (KF?) in a multi‐step reaction with natural and unnatural nucleotides. First, we confirmed the applicability of unnatural nucleotides with 7‐deaza‐nucleosides—which was expected because they were non‐metalized nucleotides—on the unique polymerization process known as the “strand‐slippage model”. Because the length of the DNA sequence could be controlled by tuning the reaction time, analogous to a living polymerization reaction on this process, stepwise polymerization provided DNA block copolymers with natural and unnatural bases. AFM images showed that this DNA block copolymer could be metalized sequence‐selectively. This approach could expand the utility of DNA as a template. 相似文献
669.
Sumikazu Ogata Hideyuki Tagaya Jun-Ichi Kadokawa Koji Chiba 《Molecular Crystals and Liquid Crystals》2013,570(2):419-424
Abstract A new preparation method of the fibrous organic-inorganic nanohybrids was established by the reaction of Zn(OH)2 with various organic carboxylic acids. Interlayer spacings of the reaction products of Zn(OH)2 with benzoic acid and p-phenyl azobenzoic acid were 1.46 and 2.04 nm, and these reaction products have layered structure. In IR spectra, new peaks of RCOO-Zn band appeared at around 1400 cm?1 and 1550 cm?1 indicating that hydroxyl groups reacted with organic carboxylic acids. SEM images of these reaction products showed fibrous morphology. The TEM image showed that the layer structure was constructed along the fiber direction. 相似文献
670.
Norio Kashiwa Tomoaki Matsugi Shin-Ichi Kojoh Hideyuki Kaneko Nobuo Kawahara Shingo Matsuo Tadahito Nobori Jun-Ichi Imuta 《Journal of polymer science. Part A, Polymer chemistry》2003,41(22):3657-3666
The control of hydroxylated polyethylene (PE) structures was investigated in the copolymerization of ethylene with allyl alcohol or 10-undecen-1-ol with a specific metallocene, methylaluminoxane, and trialkyl aluminum catalyst system through changes in the copolymerization conditions. The incorporation of allyl alcohol into the PE backbones was controllable through changes in the trialkyl aluminum, leading to terminally hydroxylated PE or a copolymer possessing hydroxyalkyl side chains. The copolymerization of ethylene with 10-undecen-1-ol gave copolymers with hydroxyalkyl side chains of various contents with a variety of molecular weights through changes in the copolymerization conditions. The obtained copolymers were useful as macroinitiators that allowed polar polymer segments to grow on the PE backbones, leading to the creation of graft copolymers that possessed PE and polar polymer segments. In this way, polyethylene-g-poly(propylene glycol) (PE-g-PPG) and polyethylene-g-poly(ϵ-caprolactone) (PE-g-PCL) were synthesized. The 13C NMR analysis of PE-g-PPG suggested that all the hydroxyl groups were consumed for propylene oxide polymerization, and transmission electron microscopy demonstrated nanoorder phase separation and indistinct phase boundaries. 13C NMR and gel permeation chromatography analyses indicated the formation of PE-g-PCL, in which 36–80 mol % of the hydroxyl groups worked as initiators for ϵ-caprolactone polymerization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3657–3666, 2003 相似文献