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991.
Reiko Saito Toshifumi Kanahara Masahiro Oguchi Hiroshi Nakaseko 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(4):362-368
In order to control microphase separation of polystyrene-silica nanocomposites, perhydropolysilazane (PHPS), which is a preceramic of silica, and epoxidized poly(styrene-block-butadiene-block-styrene) triblock copolymer [E-SBS, Mw = 8.0 × 104, styrene: 40 mol%, degree of epoxidization of butadiene: 20 mol%] or poly(styrene-block-butadiene-block-styrene) triblock copolymer [SBS, Mw = 1.40 × 105, styrene: 30 mol%] as templates of microphase separation were blended, following the calcination of composites in steam at 60°C. Well-arranged microphase separation was formed with E-SBS, though the macrophase separation was formed with SBS. The morphology of the microphase separation of the composites with E-SBS and PHPS was widely controlled by varying the PHPS content based on Molau's law. Silica domains were formed in polybutadiene domains. NMR analysis indicated the interaction between silanyl group of PHPS and epoxy group in E-SBS. The composites on the substrate were highly transparent and the surface of the composite with 73.5 vol% of silica was harder than 4H. 相似文献
992.
Masaichi Saito Ryuta Haga Michikazu Yoshioka 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4-5):703-705
Reduction of 1-t-butyl-1,2,3,4,5-pentaphenylstannole by lithium gave the stannole dianion. Reduction of the bi(1,1-stannole) having a t-butyl group on the tin by lithium also gave the stannole dianion, the formation of which was evidenced by spectral analysis and chemical trapping reaction. 相似文献
993.
Ikue Homma Takuya Isogai Tsuguyuki Saito Akira Isogai 《Cellulose (London, England)》2013,20(2):795-805
The biodegradation behavior of 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized cellulose fibers (TOCs) suspended in water and TEMPO-oxidized cellulose nanofibrils (TOCNs) dispersed in water by a commercial crude cellulase was studied. Products crude cellulase-treated for 0–7 days were separated into water/ethanol-insoluble and -soluble fractions. Weight recovery ratios and viscosity-average degrees of polymerization of the water/ethanol-insoluble fractions clearly decreased with crude cellulase-treatment time, showing that both TOCs and TOCNs have biodegradability. Water/ethanol-soluble fractions were subjected to size-exclusion chromatography (SEC) with photodiode array (PDA) detection to obtain SEC elution patterns detected by reflective index and UV spectra of each SEC pattern elution slice. SEC–PDA and 13C-NMR analyses showed that glucuronosyl unit-containing molecules present on microfibril surfaces in TOCs and TOCNs were primarily cleaved by hydrolyzing enzymes present as contaminants in the crude cellulase to form glucuronic acid as one of the major water-soluble degradation compounds. After the glucuronosyl units in TOCs and TOCNs were degraded and removed from microfibril surfaces by the hydrolyzing enzymes, cellulose chains newly exposed on the microfibril surfaces were rapidly hydrolyzed by cellulases predominantly present in the crude cellulase to form cellobiose. Both TOCs and TOCNs having sodium carboxyl groups are thus biodegradable, but TOCN having free carboxyl groups had clearly low biodegradability by the crude cellulase. Thus, biodegradation behavior may be controllable by controlling the structure of carboxyl group counter ions in TOCs and TOCNs. 相似文献
994.
Benjamin Briois Tsuguyuki Saito Christian Pétrier Jean-Luc Putaux Yoshiharu Nishiyama Laurent Heux Sonia Molina-Boisseau 《Cellulose (London, England)》2013,20(2):597-603
Aqueous suspensions of dispersed Glaucocystis cellulose microfibrils were sonicated at 4 °C for 3 h, using 24 kHz ultrasonic waves. This treatment induced a variety of ultrastructural defects, as the microfibrils became not only shortened, but also presented substantial damage materialized by kinks and subfibrillation. Upon analysis by X-ray diffraction and 13C solid-state NMR spectroscopy, it was found that the initial sample that contained 90 % of cellulose Iα allomorph became, to a large extent, unexpectedly converted into the Iβ phase, while the loss of crystallinity was only moderate during the sonication treatment. 相似文献
995.
Sina Schwendemann Shunsuke Oishi Prof. Dr. Susumu Saito Dr. Roland Fröhlich Dr. Gerald Kehr Prof. Dr. Gerhard Erker 《化学:亚洲杂志》2013,8(1):212-217
D ‐(+)‐Camphor forms the enamine 2 with piperidine. Compound 2 adds HB(C6F5)2 at the enamine carbon atom C3 to form a Lewis acid/Lewis base adduct (exo‐/endo‐isomers of 3 ). Exposure of 3 to dihydrogen (2.5 bar, room temperature) leads to heterolytic splitting of H2 to form the H+/H? addition products ( 4 , two diastereoisomers) of the “invisible” frustrated Lewis pairs ( 5 , two diastereoisomers) that were apparently generated in situ by enamine hydroboration under equilibrium conditions. 相似文献
996.
Dr. Dmitri V. Konarev Prof. Sergey I. Troyanov Dr. Salavat S. Khasanov Dr. Akihiro Otsuka Prof. Hideki Yamochi Prof. Gunzi Saito Prof. Rimma N. Lyubovskaya 《化学:亚洲杂志》2013,8(6):1139-1143
A new salt, (PPN+)2(C702?) ? 2 C6H4Cl2 ( 1 ), which contains C702? dianions, has been obtained as single crystals (PPN+=bis(triphenylphosphine)iminium cation). The C702? dianions form polymeric zigzag (C702?)n chains, in which the fullerene units are bonded through single C? C bonds of length 1.581(5)–1.586(6) Å. The distance between the centers of neighboring C702? units is 10.441 Å. The optical and magnetic properties of (C702?)n have also been studied. Decreasing the symmetry of C70 in the polymer activate about 20 new IR bands in addition to the 10 IR‐active bands of the starting C70. The polymeric structure shows absorptions in the visible and NIR regions, with three main bands at 890, 1200, and 1550 nm, instead of one band of isolated C702? dianions at 1165–1184 nm. We concluded that the (C702?)n polymer was diamagnetic, with a negative molar magnetic susceptibility of ?3.82×10?4 emu mol?1 per C702? dianion. The polymer is EPR silent and a weak narrow EPR signal in salt 1 is due to impurities, which only constitute 0.84 % of spin S=1/2 of the total amount of fullerene C70. 相似文献
997.
Solid-phase oligopeptide synthesis has been well developed and most short oligopeptides can now be easily synthesized. However, when a desired oligopeptide forms a secondary structure or includes less reactive amino acids such as aminoisobutyric acid, its terminal amino groups become less reactive and synthesis of the desired oligopeptides becomes difficult. To expand the number of synthetic peptide sequences, we have developed efficient coupling conditions using 3-nitro-l,2,4-triazol-l-yl-tris(pyrrolidin-1-yl)phosphonium hexafluorophosphate (PyNTP) as a highly reactive condensing reagent on an unswellable solid support. PyNTP demonstrated higher reactivity than conventional condensing reagents and the optical purity of the synthesized oligopeptides was sufficiently high for application to general oligopeptide synthesis. 相似文献
998.
Eisaku Sumino Shougo Ise Tomoya Saito Masakazu Nishida Tsuyoshi Noguchi Hideo Sawada 《Colloid and polymer science》2014,292(2):369-379
Perfluoro-2-methyl-3-oxahexanoic acid/silica nanocomposites [RF-CO2H/SiO2] were prepared by the sol–gel reaction of tetraethoxysilane in the presence of silica nanoparticles and the corresponding fluorinated carboxylic acid under alkaline conditions. RF-CO2H/SiO2 nanocomposites were found to exhibit no weight loss in proportion to the contents of fluorinated carboxylic acid in the composites even after calcination at 800 °C. The modified glass surface treated with the RF-CO2H/SiO2 nanocomposites was shown to give a good oleophobicity with superhydrophilicity imparted by fluorinated carboxylic acid in the composites. RF-CO2H/SiO2 nanocomposites were also applied to the encapsulation of a variety of low molecular weight aromatic and aliphatic compounds such as bisphenol AF [BPAF], bisphenol A [BPA], 4,4′-biphenol [BPOH], octafluoro-4,4′-biphenol [FBPOH], 4,4′-bis(triethoxysilyl)-1,1′-biphenyl [BTSBP], 3-(trihydroxysilyl)propane-1-sulfonic acid [THSP], α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), and γ-cyclodextrin (γ-CD). Encapsulated aromatic compounds possessing acidic hydroxyl groups such as BPAF, BPA, and FBPOH in the RF-COOH/SiO2 nanocomposites were found to exhibit no weight loss corresponding to the contents of aromatic compounds in the composites even after calcination at 800 °C. On the other hand, encapsulated aromatic compounds possessing no acidic hydroxyl groups such as BTSBP and aliphatic compounds (THSP, α-, β-, and γ-CD) gave a clear weight loss corresponding to the contents of these compounds in the composites after calcination. In addition, the fluorinated silica nanocomposite-encapsulated these compounds were applied to the surface modification of glass to exhibit a good oleophobicity with superhydrophilicity imparted by fluorinated carboxylic acid on the surface. Figure
? 相似文献
999.
The imbibition of a solid island on a substrate with a square array of pillars is studied by means of kinetic Monte Carlo simulations. Imbibition is found to occur via an intermediate state where an island sits on the film. Two dynamical regimes are identified depending on the geometry of the substrate: a stochastic regime, where the dynamics are controlled by the nucleation-limited motion of the imbibition front across the array of pillars, and a deterministic regime limited by the diffusion of atoms on top of the imbibition film. 相似文献
1000.
Sakai K Stoychev S Ouchi T Higuchi I Schöffler M Mazza T Fukuzawa H Nagaya K Yao M Tamenori Y Kuleff AI Saito N Ueda K 《Physical review letters》2011,106(3):033401
We report the first observation of electron-transfer-mediated decay (ETMD) and interatomic Coulombic decay (ICD) from the triply charged states with an inner-valence vacancy, using the Ar dimer as an example. These ETMD and ICD processes, which lead to fragmentation of Ar(3+)-Ar into Ar(2+)-Ar(2+) and Ar(3+)-Ar+, respectively, are unambiguously identified by electron-ion-ion coincidence spectroscopy in which the kinetic energy of the ETMD or ICD electron and the kinetic energy release between the two fragment ions are measured in coincidence. 相似文献