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51.
Matsuura H Nomura S Subeki Yamada K Yamasaki M Yamato O Maede Y Katakura K Trimurningsih Chairul Yoshihara T Nabeta K 《Natural product research》2007,21(4):328-333
Anti-babesial ingredients, (12R)- and (12S)-12,13-dihydro-12,13-dihydroxyxanthorrhizols, were isolated from Curcuma xanthorrhiza. The structures were established by the extensive NMR techniques. The assignments of (1)H NMR data of (12R)-12,13-dihydro-12,13-dihydroxyxanthorrhizol was revised, and (12S)-12,13-dihydro-12,13-dihydroxyxanthorrhizol was isolated as a pure form for the first time. The IC(50) of the active compounds were compared with that of commercial drug, diminazene aceturate (Ganaseg). IC(50) values of Ganaseg, (12R)-, and (12S)-12,13-dihydro-12,13-dihydroxyxanthorrhizols were 0.6 microg mL(-1), 8.3 microg mL(-1) and 11.6 microg mL(-1), respectively. 相似文献
52.
Polymersomes Prepared from Thermoresponsive Fluorescent Protein–Polymer Bioconjugates: Capture of and Report on Drug and Protein Payloads 下载免费PDF全文
Chin Ken Wong Alistair J. Laos Dr. Alexander H. Soeriyadi Prof. Jörg Wiedenmann Prof. Paul M. G. Curmi Prof. J. Justin Gooding Dr. Christopher P. Marquis Prof. Martina H. Stenzel Assoc. Prof. Pall Thordarson 《Angewandte Chemie (International ed. in English)》2015,54(18):5317-5322
Polymersomes provide a good platform for targeted drug delivery and the creation of complex (bio)catalytically active systems for research in synthetic biology. To realize these applications requires both spatial control over the encapsulation components in these polymersomes and a means to report where the components are in the polymersomes. To address these twin challenges, we synthesized the protein–polymer bioconjugate PNIPAM‐b‐amilFP497 composed of thermoresponsive poly(N‐isopropylacrylamide) (PNIPAM) and a green‐fluorescent protein variant (amilFP497). Above 37 °C, this bioconjugate forms polymersomes that can (co‐)encapsulate the fluorescent drug doxorubicin and the fluorescent light‐harvesting protein phycoerythrin 545 (PE545). Using fluorescence lifetime imaging microscopy and Förster resonance energy transfer (FLIM‐FRET), we can distinguish the co‐encapsulated PE545 protein inside the polymersome membrane while doxorubicin is found both in the polymersome core and membrane. 相似文献
53.
Carbazole Dendrimers as Solution‐Processable Thermally Activated Delayed‐Fluorescence Materials 下载免费PDF全文
Assist. Prof. Ken Albrecht Assist. Prof. Kenichi Matsuoka Assoc. Prof. Katsuhiko Fujita Prof. Kimihisa Yamamoto 《Angewandte Chemie (International ed. in English)》2015,54(19):5677-5682
Recently, thermally activated delayed fluorescence (TADF) materials have received increasing attention as effective emitters for organic light‐emitting diodes (OLEDs). However, most of them are usually employed as dopants in a host material. In this report, carbazole dendrimers with a triphenyl‐s‐triazine core are reported, which are the first solution‐processable, non‐doped, high‐molecular‐weight TADF materials. The dendrimers were obtained by a new and facile synthetic route using the tert‐butyldimethylsilyl moiety as a protecting group. All dendrimers showed TADF in toluene. Measurements of the temperature‐dependent luminescence lifetime revealed that spin‐coated neat films also showed TADF with moderate quantum yields. OLED devices incorporating these dendrimers as spin‐coated emitting layers gave external quantum efficiencies of up to a 3.4 %, which suggests that this device is harvesting triplet excitons. This result indicates that carbazole dendrimers with attached acceptors are potential TADF materials owing to their polarized electronic structure (with HOMO–LUMO separation). 相似文献
54.
Xin‐Gang Xie Dr. Xun‐Wei Wu Dr. Hing‐Ken Lee Dr. Xiao‐Shui Peng Prof. Dr. Henry N. C. Wong Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(23):6933-6941
Plakortone B is a naturally occurring bicyclic[3.3.0]furanolactone compound with attractive bioactivities. Although the relative configuration of plakortone B’s central core had been established by NMR spectroscopic methods, the absolute configuration of its four stereocenters remained unknown. In the present paper, all four possible isomers of plakortone B were synthesized and one of these molecules was found to be identical with the natural plakortone B on the basis of 1H, 13C NMR spectra and specific rotation comparisons. Thus, the absolute configuration of the natural plakortone B was determined to be (3S,4S,6R,10R). 相似文献
55.
56.
Dynamics of ice nucleation on water repellent surfaces 总被引:3,自引:0,他引:3
Alizadeh A Yamada M Li R Shang W Otta S Zhong S Ge L Dhinojwala A Conway KR Bahadur V Vinciquerra AJ Stephens B Blohm ML 《Langmuir : the ACS journal of surfaces and colloids》2012,28(6):3180-3186
Prevention of ice accretion and adhesion on surfaces is relevant to many applications, leading to improved operation safety, increased energy efficiency, and cost reduction. Development of passive nonicing coatings is highly desirable, since current antiicing strategies are energy and cost intensive. Superhydrophobicity has been proposed as a lead passive nonicing strategy, yet the exact mechanism of delayed icing on these surfaces is not clearly understood. In this work, we present an in-depth analysis of ice formation dynamics upon water droplet impact on surfaces with different wettabilities. We experimentally demonstrate that ice nucleation under low-humidity conditions can be delayed through control of surface chemistry and texture. Combining infrared (IR) thermometry and high-speed photography, we observe that the reduction of water-surface contact area on superhydrophobic surfaces plays a dual role in delaying nucleation: first by reducing heat transfer and second by reducing the probability of heterogeneous nucleation at the water-substrate interface. This work also includes an analysis (based on classical nucleation theory) to estimate various homogeneous and heterogeneous nucleation rates in icing situations. The key finding is that ice nucleation delay on superhydrophobic surfaces is more prominent at moderate degrees of supercooling, while closer to the homogeneous nucleation temperature, bulk and air-water interface nucleation effects become equally important. The study presented here offers a comprehensive perspective on the efficacy of textured surfaces for nonicing applications. 相似文献
57.
58.
Fukuzumi S Okamoto K Tokuda Y Gros CP Guilard R 《Journal of the American Chemical Society》2004,126(51):17059-17066
Dehydrogenation of 10-methyl-9,10-dihydroacridine (AcrH(2)) by dioxygen (O(2)) proceeds efficiently, accompanied by the two-electron and four-electron reduction of O(2) to produce H(2)O(2) and H(2)O, which are effectively catalyzed by monomeric cobalt porphyrins and cofacial dicobalt porphyrins in the presence of perchloric acid (HClO(4)) in acetonitrile (MeCN) and benzonitrile (PhCN), respectively. The cobalt porphyrin catalyzed two-electron reduction of O(2) also occurs efficiently by 9-alkyl-10-methyl-9,10-dihydroacridines (AcrHR; R = Me, Et, and CH(2)COOEt) to yield 9-alkyl-10-methylacridinium ion (AcrR+) and H(2)O(2). In the case of R = Bu(t) and CMe(2)COOMe, however, the catalytic two-electron and four-electron reduction of O(2) by AcrHR results in oxygenation of the alkyl group of AcrHR rather than dehydrogenation to yield 10-methylacridinium ion (AcrH+) and the oxygenated products of the alkyl groups, i.e., the corresponding hydroperoxides (ROOH) and the alcohol (ROH), respectively. The catalytic mechanisms of the dehydrogenation vs the oxygenation of AcrHR in the two-electron and four-electron reduction of O(2), catalyzed by monomeric cobalt porphyrins and cofacial dicobalt porphyrins, respectively, are discussed in relation to the C(9)-H or C(9)-C bond cleavage of AcrHR radical cations produced in the electron-transfer oxidation of AcrHR. 相似文献
59.
Yong S. Chong Dr. William R. Carroll William G. Burns Mark D. Smith Ken D. Shimizu Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(36):9117-9126
An atropisomeric molecular balance was developed to study face‐to‐face arene–arene interactions. The balance has a large central 1,4,5,8‐naphthalene diimide surface that forms intramolecular arene–arene interactions with two pendent arms. The balance adopts distinct syn and anti isomers with varying numbers of intramolecular interactions. Thus, the strength of the arene–arene interaction could be quantitatively measured by NMR spectroscopy from the anti/syn ratios. The size of the arene arms was easily varied, which allowed examination of the relationship between arene size and strength of the interaction. A nonlinear size dependence was observed in solution with larger arene arms having a disproportionately stronger arene–arene interaction. The intramolecular arene–arene interactions were also characterized in the solid state by X‐ray crystallography. These studies were facilitated by the kinetic stability of the syn and anti isomers at room temperature due to the high isomerization barrier (ΔG=27.0 kcal mol?1). Thus, the anti isomer could be selectively isolated and crystallized in its folded conformation. The X‐ray structures confirmed that the anti isomers formed two strong intramolecular arene–arene interactions with face‐to‐face geometries. The solid‐state structure analysis also reveals that the rigid framework may contribute to the observed nonlinear size trend. The acetate linker is slightly too long, which selectively destabilizes the balances with smaller arene arms. The larger arene arms are able to compensate for the longer linker and form effective intramolecular arene–arene interactions. 相似文献
60.
Hiroaki Aizawa Ken Hatano Hitoshi Saeki Nobuaki Honsho Tetsuo Koyama Koji Matsuoka Daiyo Terunuma 《Tetrahedron letters》2010,51(12):1545-6442
A new compound having a 2,3,4,5-tetraphenylsilole derivative on the center silicon of Dumbbell(1)6Gb3; Silole-Dumbbell(1)6Gb3 (1) was previously reported. It was found that 1 exhibited strongly increased fluorescence both in water and in a 96% acetone/water mixed solvent. The physical behavior of 1 in water and in the 96% acetone/water mixed solvent was investigated, and analyses including fluorescence quantum yields, dynamic-light-scattering (DLS), atomic-force-microscopy (AFM), and fluorescence microscopy were carried out. It was clarified that 1 dynamically formed different types of aggregates in water and in higher acetone concentrations to yield high aggregation-induced emission (AIE) effects due to the formation of micelle-like particles in water and inversion-type micelles in the acetone/water mixed solvent, respectively. 相似文献