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791.
Shokyoku Kanaoka Masanori Sueoka Mitsuo Sawamoto Toshinobu Higashimura 《Journal of polymer science. Part A, Polymer chemistry》1993,31(10):2513-2521
Amphiphilic graft polymers of vinyl ethers (VEs) ( 6 ) where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(alkyl vinyl ether) segment were prepared on the basis of living cationic polymerization, and their properties and functions were compared with the corresponding amphiphilic star-shaped polymers. In toluene at ?15°C, the HI/ZnI2-initiated living block polymer 2 of an ester-containing VE (CH2? CHOCH2CH2OCOCH3) and isobutyl VE (IBVE) was terminated with the diethyl 2-(vinyloxy)ethylmalonate anion [ 3 ; ΦC(COOEt)2CH2CH2OCH ? CH2] ( 2/3 = 1/2 mole ratio) to give a macromonomer ( 4 ), H[CH2CH(OCH2CH2OCOCH3)] m-[CH2CH(OiBu)]n? C(COOEt)2CH2CH2OCH ? CH2 (m = 5, n = 15; M?n = 2600, M?w/M?n = 1.13, 1.10 vinyl groups/chain). Subsequently, 4 was homopolymerized with HI/ZnI2 in toluene at ?15°C. In 3 h, 85% of 4 was consumed and a graft polymer ( 5 ) was obtained [M?w = 15000, DPn (for 4 ) = 6]. The apparent M?w (10,900) of 5 by size-exclusion chromatography (SEC) is smaller than that by light scattering as well as that (18,300) by SEC of the corresponding linear polymer with the almost same molecular weight, indicating the formation of a multi-branched structure. Hydrolysis of the pendant esters in 5 gave the amphiphilic graft polymer 6 where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(IBVE) segment. The graft polymer 6 was found to interact specifically with small organic molecules (guests) with polar functional groups, and 6 differed in solubility and host-guest interaction from the corresponding star-shaped polymer. © 1993 John Wiley & Sons, Inc. 相似文献
792.
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
793.
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
794.
Hideyuki Katsumata Hiroshi Kojima Satoshi Kaneco Tohru Suzuki Kiyohisa Ohta 《Microchemical Journal》2010,96(2):348-351
A sensitive and selective preconcentration method using solid-phase extraction (SPE) disk, namely multiwalled carbon nanotubes (MWCNTs) disk, is proposed for the determination of atrazine and simazine in water samples. Atrazine and simazine were extracted on MWCNTs disk and then determined by gas chromatography–mass spectrometry (GC/MS). Several parameters on the enrichment factor of the analytes were investigated. The experimental results showed that it was possible to obtain quantitative analysis when the solution pH was 5 using 200 mL of validation solution containing 0.1 μg of triazines and 5 mL of acetone as an eluent. The maximum enrichment factors for atrazine and simazine were 3900 ± 250 and 4000 ± 110, respectively when 200 mL of sample solution volume was used. Relative standard deviations for seven determinations were 6.9% (atrazine) and 3.0% (simazine) under optimum conditions. The linear range of calibration curves were 0.1 to 1 ng mL− 1 for each analyte with good correlation coefficients. The detection limits (3S/N) were 2.5 and 5.0 pg mL− 1 for atrazine and simazine, respectively. The proposed method was successfully applied to the determination of atrazine and simazine in environmental water samples with high precision and accuracy. 相似文献
795.
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
796.
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
797.
The transport properties of a novel porous fluorinated polyimide membrane fabricated by a wet phase inversion process were studied with a stirred dead‐end filtration cell. The porous membrane‐forming solvents were tetrahydrofuran (THF), acetone, N,N‐dimethylacetamide (DMAc), N‐methylpyrrolidone (NMP), N,N‐dimethylformamide (DMF), and dimethylsulfoxide (DMSO). The phase separation phenomena in a ternary system of polyimide/solvent/water were investigated from cloud point curves by a titration method and binary interaction parameters. Solvent–water demixing in the system has been found to play very important roles in determining the structure and surface morphology of the polyimide membrane. The porous fluorinated polyimide membranes showed pore sizes from 4 to 500 nm and permeation properties from ultrafiltration to a microfiltration range. In this study, we particularly focused on fouling of the polyimide membranes, because fouling decreases the flux and increases the resistance. Interestingly, the porous polyimide membrane showed excellent water flux recovery after water cleaning compared with that of the polyethersulfone (PSf) membrane, which suggest that for a 6FDA‐6FAP membrane, the protein–membrane and protein–protein interaction was not so strong compared with those in a PSf membrane. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
798.
Morphological studies of a hydrogen-bonded LC polymer obtained by photopolymerization in LC solvents 总被引:1,自引:0,他引:1
Hideyuki Kihara Toshiaki Miura Ryoichi Kishi Takashi Yoshida Mitsuhiro Shibata Ryutoku Yosomiya 《Liquid crystals》2003,30(7):799-809
Anisotropic morphologies and the phase behaviour of a hydrogen-bonded LC polymer obtained by photopolymerization in two kinds of LC solvent are discussed. The hydrogen-bonded LC monomer, 4-(6-acryloyloxyhexyloxy) benzoic acid (A6OBA), was photopolymerized in 4-cyano-4'-hexyloxybiphenyl (6OCB) and in 4-cyano-4'-undecyloxybiphenyl (11OCB), which show a nematic phase and a smectic A phase, respectively. After photo-polymerization, the LC media were removed by extraction and the pure polymer was observed by scanning electron microscopy. SEM images showed that the polymer possessed fibrous morphology with a fibre diameter of a few micrometers, based on polymerization-induced phase separation. The overall geometries reflected typical LC characteristics such as schlieren and focal-conic fan textures. It was found that the hydrogen bond between benzoic acid groups in the monomer was rigid enough to fix the anisotropic phase-separated structure forming during the early stage of phase separation; however, it could not permanently maintain the fibre structure due to dissociation at elevated temperature. X-ray measurements revealed that a well developed layer structure of the hydrogen-bonded mesogen existed in the polymer obtained from the smectic phase of 11OCB, whereas a polymer layer structure could develop only partially from the nematic phase of 6OCB. 相似文献
799.
Hideyuki Yoshizawa Takashi Mihara Naoyuki Koide Corresponding author 《Liquid crystals》2013,40(1):143-149
We have synthesized liquid crystalline polymers containing an imidazolium salt moiety and a mesogenic group by the in situ photopolymerization of a liquid crystalline vinylimidazole monomer in order to investigate the relationship between their thermal properties and ionic conductivity. A smectic phase was shown by the vinylimidazole monomer. The in situ photopolymerization of the monomer was carried out in the temperature range of the smectic phase. The polymer thus prepared displayed a highly ordered smectic phase in the temperature range between room temperature and about 200°C. The ionic conductivity of the polymer increased with increasing temperature. Anisotropic ionic conductivity behavior was observed for the polymer. The ionic conductivity of the polymer aligned homogeneously is larger than when homeotropically aligned. 相似文献
800.
A naked-eye detection method for a trace amount of arsenic in aqueous samples has been newly developed. The proposed method is based on the formation of a hetero poly acid in a chelating resin phase. Molybdenum loaded on a chelating resin having β-hydroxypropyl-di(β-hydroxyethyl) amino moiety reacts with arsenic(V) to form the hetero poly acid, which makes the resin beads greenish blue in the presence of a reducing agent under acidic conditions. It was also found that the intensity of the color of the resin depends on the concentration of arsenic(V) in the sample solutions. Since the development of the color occurs in 20 min by heating of the mixture at 40 °C, this system can provide a simple, rapid and low-cost detection method of a trace amount of arsenic(V) in an aqueous media. The detection limit of this method is 1 × 10−6 mol dm−3. A longer preconcentration time with the same resin gave the higher sensitivity of 1 × 10−7 mol dm−3 that is comparable with that of the instrumental analysis. The present method comprises both the concentration and detection step with the same solid material, and hence it gives higher sensitivity and easier handling than the ordinary colorimetric methods using a liquid medium. 相似文献