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331.
Ohnuki H Saiki T Kusakari A Endo H Ichihara M Izumi M 《Langmuir : the ACS journal of surfaces and colloids》2007,23(8):4675-4681
Glucose oxidase (GOx) was immobilized in the organic-inorganic Langmuir-Bldogett (LB) films consisting of octadecyltrimethylammonium (ODTA) and nanosized Prussian blue (PB) clusters. The amperometric glucose biosensors based on the LB films were fabricated and tested. It was found that the sensors exhibited a clear response current under an applied voltage of 0.0 V (vs Ag/AgCl). The linearity of current density versus glucose concentration was confirmed below 15 mmol/L concentration. This is the first observation of biosensor function of the hybrid organic-inorganic LB films. The successful preparation of glucose sensors operating at the very low potential indicates that the adsorbed PB clusters in the LB films act as an electrocatalyst for the electrochemical reduction of hydrogen peroxide, which is the final product of the enzymatic reaction sequence. The observed low potential applicability is estimated to inhibit the responses of interferants such as ascorbic acid, uric acid, and acetominophen. It was also found that an electrostatic interaction between positively charged ODTA+ and the adsorbed species of both GOx and PB provided a stabilized adsorption state in the LB films. Such stable immobilization contributes to the steady amperometric response current observed in the present ODTA/PB/GOx LB films. 相似文献
332.
DNA is a genetic material found in all life on Earth. DNA is composed of four types of nucleotide subunits, and forms a double-helical one-dimensional polyelectrolyte chain. If we focus on the microscopic molecular structure, DNA is a rigid rod-like molecule. On the other hand, with coarse graining, a long-chain DNA exhibits fluctuating behavior over the whole molecule due to thermal fluctuation. Owe to its semiflexible nature, individual giant DNA molecule undergoes a large discrete transition in the higher-order structure. In this folding transition into a compact state, small ions in the solution have a critical effect, since DNA is highly charged. In the present article, we interpret the characteristic features of DNA compaction while paying special attention to the role of small ions, in relation to a variety of single-chain morphologies generated as a result of compaction. 相似文献
333.
Synthesis and positive‐imaging photosensitivity of soluble polyimides having pendant carboxyl groups
Takafumi Fukushima Katsumoto Hosokawa Toshiyuki Oyama Takao Iijima Masao Tomoi Hiroshi Itatani 《Journal of polymer science. Part A, Polymer chemistry》2001,39(6):934-946
Polyimides having pendant carboxyl groups were prepared by a direct one‐pot polycondensation of 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) with 3,5‐diaminobenzoic acid (DABz) and bis[4‐(3‐aminophenoxy)phenyl]sulfone (m‐BAPS) in the presence of a γ‐valerolactone/pyridine catalyst system using N‐methyl‐2‐pyrrolidone (NMP)/toluene mixture as a solvent at 180 °C. The obtained polyimides were soluble in dipolar aprotic solvents such as dimethylformamide, dimethyl sulfoxide, and NMP as well as in tetrahydrofuran and aqueous basic solution. The solubility of the polyimides was dependent on the diamine composition. Photosensitve polyimide (PSPI) systems composed of the polyimides and diazonaphthoquinone compound as a photosensitive material gave positive‐tone behavior by UV irradiation, followed by development with aqueous tetramethylammonium hydroxide (TMAH) solution. The scanning electron microscopic photograph of the resulting image showed 10‐μm line/space resolution with about 15 μm of film thickness. The PSPIs baked at 350 °C for a short time had excellent thermal resistance comparable to the original polyimides. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 934–946, 2001 相似文献
334.
335.
Youngji Cho Jun-Seok Ha Mina Jung Hyun-Jae Lee Seunghwan Park Jinsub Park Katsushi Fujii Ryuichi Toba Samnyung Yi Gyung-Suk Kil Jiho Chang Takafumi Yao 《Journal of Crystal Growth》2010,312(10):1693-1696
The present study focused on the effect of an intermediate-temperature (IT; ∼900 °C) buffer layer on GaN films, grown on an AlN/sapphire template by hydride vapor phase epitaxy (HVPE). In this paper, the surface morphology, structural quality, residual strain, and luminescence properties are discussed in terms of the effect of the buffer layer. The GaN film with an IT-buffer revealed a relatively lower screw-dislocation density (3.29×107 cm−2) and a higher edge-dislocation density (8.157×109 cm−2) than the GaN film without an IT-buffer. Moreover, the IT-buffer reduced the residual strain and improved the luminescence. We found that the IT-buffer played an important role in the reduction of residual strain and screw-dislocation density in the overgrown layer through the generation of edge-type dislocations and the spontaneous treatment of the threading dislocation by interrupting the growth and increasing the temperature. 相似文献
336.
T. Kitazawa Mi. Takahashi Ma. Takahashi M. Enomoto A. Miyazaki T. Enoki M. Takeda 《Journal of Radioanalytical and Nuclear Chemistry》1999,239(2):285-290
The coordination polymer Fe(3-chloropyridine)2Ni(CN)4 (2) has been prepared by a method similar to that for Fe(pyridine)2Ni(CN)4 (1). The complex (2) has been characterized by57Fe Mössbauer spectroscopy and a SQUID technique.57Fe Mössbauer and magnetic susceptibility data show that complex (2) exhibits spin-crossover behavior. The spin transition of (2) occurs between 120 and 80 K with very small hysteresis or without hysteresis. The temperature range of the spin transition in (2) is lower than that in (1). A residual high spin iron(II) fraction is observed at low temperatures in (2), being different from (1). SQUID data also show that samples treated differently yield different spin transition curves. 相似文献
337.
Dragoe N. Nakahara K. Xiao L. Shimotani H. Kitazawa K. 《Journal of Thermal Analysis and Calorimetry》1999,56(1):167-173
The thermal decomposition of methano-fullerene derivatives such as ethoxycarbonyl methano[60] fullerene and various isomers
of bis-(ethoxycarbonyl methano)[60] fullerene leads to new fullerene derivatives, which have been preliminary characterized.
The analysis of separated species was performed by UV-VIS, IR, H- and C-NMR, STM, FAB, LDI and MALDI-TOF MS spectroscopy.
One of the isolated phases is a C122 molecule with a dumbbell-like structure.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
338.
Kazuhiro Higuchi Kazunori Matsumura Takafumi Arai Motoki Ito Shigeo Sugiyama 《Molecules (Basel, Switzerland)》2022,27(1)
Propellanes are polycyclic compounds in which tricyclic systems share one carbon–carbon single bond. Propellane frameworks that consist of larger sized rings are found in a variety of natural products. As an approach to the stereoselective synthesis of the propellane framework, one of the efficient methods is forming several rings in a single operation. Lapidilectine B (1) is composed of a propellane framework and was synthesized through the oxidative cyclization of trisubstituted alkenes. When the alkene with an ester moiety was treated with N-iodosuccinimide (NIS), iodocyclization proceeded to give the cyclic carbamate. On the other hand, when PhI(OAc)2 was allowed to react in the carboxyl form, a furoindolin-2-one structure corresponding to the A-B-C ring of lapidilectine B (1) was produced. Furthermore, when Pd(OAc)2 catalyst was used for cyclization under oxidative conditions, the product yield was improved. 相似文献
339.
Yu Koizumi Xiongjie Jin Takafumi Yatabe Ray Miyazaki Jun‐ya Hasegawa Kyoko Nozaki Noritaka Mizuno Kazuya Yamaguchi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(32):11009-11013
Dehydrogenative aromatization is one of the attractive alternative methods for directly synthesizing primary anilines from NH3 and cyclohexanones. However, the selective synthesis of primary anilines is quite difficult because the desired primary aniline products and the cyclohexanone substrates readily undergo condensation affording the corresponding imines (i.e., N‐cyclohexylidene‐anilines), followed by hydrogenation to produce N‐cyclohexylanilines as the major products. In this study, primary anilines were selectively synthesized in the presence of supported Pd nanoparticle catalysts (e.g., Pd/HAP, HAP=hydroxyapatite, Ca10(PO4)6(OH)2) by utilizing competitive adsorption unique to heterogeneous catalysis; in other words, when styrene was used as a hydrogen acceptor, which preferentially adsorbs on the Pd nanoparticle surface in the presence of N‐cyclohexylidene‐anilines, various structurally diverse primary anilines were selectively synthesized from readily accessible NH3 and cyclohexanones. The Pd/HAP catalyst was reused several times though its catalytic performance gradually declined. 相似文献