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691.
Yoshio Nakahara Tsutomu Takeuchi Shoutaro Yokoyama Keiichi Kimura 《Surface and interface analysis : SIA》2011,43(4):809-815
Quantitative analysis of reacted silanol groups in silica nanoparticles modified chemically with monochlorosilanes was performed by 1H NMR after treatment with cesium fluoride. Silica nanoparticles were modified chemically by the reaction between the silanol groups and monochlorosilanes, and the structure of the organic moiety anchored onto the silica surface was confirmed with solid‐state 13C NMR. As monochlorosilanes react with silanol groups at 1:1 ratio unlike di‐ or trichlorosilanes, the number of the silanes introduced into silica nanoparticles equals that of reacted silanol groups. Organically modified silica nanoparticles were dissolved using cesium fluoride, and the amount of the soluble organic compounds originated from the introduced silanes was determined by a 1H NMR internal standard method using pyrene as the reference. Those values determined by 1H NMR were in good agreement with those determined by elemental analysis. Thus, the number of reacted silanol groups per one particle was calculated on the basis of the results obtained by the 1H NMR method, and the values were highly dependent on the steric structure of the introduced silanes. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
692.
We developed a novel hybrid sample injection mode (HSIM) that presents the combination of electrokinetic injection and vacuum injection to enhance detection sensitivity in CZE. Samples were introduced using both vacuum and electrokinetic injections simultaneously, with a water plug injected into the capillary prior to sample introduction (i.e. similarly to field-amplified sample injection, FASI). Using a sample mixture containing an anti-fouling agent applied to ship hulls, pyridine-triphenylborane and its degradation products (diphenylborinic acid, phenylboronic acid, and phenol) dissolved in ACN, the length of water plug, time, and voltage for sample introduction were optimized. The signal intensity (peak height) was found to be up to a 30-fold increased using HSIM by applying 4 kV for 4 s at the inlet end of the capillary as the cathode with supplementary vacuum in comparison with only vacuum injection for 4 s. The LODs (at a S/N of 3) for pyridine-triphenylborane, diphenylborinic acid, phenylboronic acid, and phenol were 0.88, 1.0, 21, and 23 μg/L, respectively. At the level of 0.04 mg/L, the RSDs (n=4, intra-day) for the above analytes were in the ranges of 1.9-11, 4.3-9.2, and 0.34-0.66% for peak area, peak height, and migration time, respectively. The HSIM is a simple and promising procedure useful for enhancing the sensitivity for both low-and high-mobility ions in CZE. 相似文献
693.
694.
In this paper, we propose new Euler flux functions for use in a finite-volume Euler/Navier–Stokes code, which are very simple, carbuncle-free, yet have an excellent boundary-layer-resolving capability, by combining two different Riemann solvers into one based on a rotated Riemann solver approach. We show that very economical Euler flux functions can be devised by combining the Roe solver (a full-wave solver) and the Rusanov/HLL solver (a fewer-wave solver), based on a rotated Riemann solver approach: a fewer-wave solver automatically applied in the direction normal to shocks to suppress carbuncles and a full-wave solver applied, again automatically, across shear layers to avoid an excessive amount of dissipation. The resulting flux functions can be implemented in a very simple and economical manner, in the form of the Roe solver with modified wave speeds, so that converting an existing Roe flux code into the new fluxes is an extremely simple task. They require only 7–14% extra CPU time and no problem-dependent tuning parameters. These new rotated fluxes are not only robust for shock-capturing, but also accurate for resolving shear layers. This is demonstrated by an extensive series of numerical experiments with standard finite-volume Euler and Navier–Stokes codes, including various shock instability problems and also an unstructured grid case. 相似文献
695.
Infrared spectrum of the cobalt carbonyl radical CoCO produced by the 193 nm excimer laser photolysis of cobalt tricarbonyl nitrosyl Co(CO)3NO was observed by time-resolved diode laser spectroscopy. More than 600 lines were identified as belonging to the ν1 (C-O stretch) fundamental band, consisting of the Ω=5/2 and 3/2 subbands, and the associated hot bands , , , and . The 2Δi electronic ground state of CoCO was experimentally confirmed. The ν1 band origins are 1974.172582(93) cm−1 and 1973.53178(14) cm−1 for the Ω=5/2 and 3/2 subbands, respectively. The rotational constant in the ground state was determined as B0=4427.146(50) MHz. The centrifugal distortion constant D0=1.1243(68) kHz was obtained for the Ω=5/2 substate of the ground state. The equilibrium rotational constant Be=4435.44(14) MHz was derived, together with the vibration-rotation interaction constants. 相似文献
696.
Naokazu Yoshikawa Shinichi Yamabe Nobuko Kanehisa Tsuyoshi Inoue Hiroshi Takashima Keiichi Tsukahara 《Journal of Physical Organic Chemistry》2010,23(5):431-439
A series of new metal‐free blue emission compounds, i.e., diprotonated terpyH2ClPF6 ( 1 ), tterpyH2ClPF6 ( 2 ), ClterpyH2ClPF6 ( 3 ), and BterpyH2(PF6)2 ( 4 ), were prepared and characterized by electrospray ionization mass spectrometry, UV–vis spectroscopy, and cyclic voltammetry (CV). Abbreviations used are terpy = 2,2′:6′,2″‐terpyridine, tterpy = 4′‐(4‐tolyl)‐2,2′:6′,2″‐terpyridine, Clterpy = 4′‐chloro‐2,2′:6′,2″‐terpyridine, and Bterpy = 4,4′,4″‐tert‐butyl‐2,2′:6′,2″‐terpyridine. The X‐ray crystal structures of the three new compounds 1, 2, and 4 were determined. Both protonated pyridine rings of the terpyridine derivatives are hydrogen bonded intermolecularly to the adjacent Cl? ion in compounds 1 , 2, and 3 . The π–π* absorption bands in the UV region for 1, 2, 3, and 4 in acetonitrile were red‐shifted relative to those of the corresponding neutral compounds. All the compounds exhibited stronger emissions (around 400 nm) than their neutral counterparts. All the CVs for the diprotonated species, terpyH, tterpyH, ClterpyH, and BterpyH, showed the first reduction waves around ?0.6 V, which were more positive than those of the neutral ones. Density functional theory was applied to interpret the remarkable differences in the interaction of the Cl? ion. The attachment of two protons to the two terminal Bterpy nitrogens in 4 elicits remarkable characteristics. Both positive charges on the nitrogens are delocalized over the conjugated pyridine systems and the tertiary carbonium ions are stabilized to lead to stronger emission (Φ = 0.35) than the corresponding neutral Bterpy (Φ = 0.045). CCDC 732045–732047 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
697.
Toshiyuki Takayanagi Yuzuru Kurosaki Keiichi Yokoyama 《International journal of quantum chemistry》2000,79(3):190-197
The geometry of the transition state for the N(2D) + CH4 reaction has been reoptimized at the complete‐active‐space self‐consistent field theory with a large active space and we have confirmed that the N(2D) atom initially inserts into a CH bond to form adiabatically an intermediate radical, CH3NH(2A″). Extensive single‐point calculations at the multireference configuration interaction level of theory have also been carried out to understand the feature of the potential energy surface for the C–H insertion reaction. In addition, we have found that the N(2D)+CH4 reaction dynamics on the second lowest doublet state (2A′) is dominated by C–H insertion although the barrier height is somewhat larger in energy than the corresponding insertion barrier associated with the lowest doublet state. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 79: 190–197, 2000 相似文献
698.
Keiichi Moriya Takahiro Seki Masaru Nakagawa Guoping Mao Christopher K. Ober 《Macromolecular rapid communications》2000,21(18):1309-1312
The UV and V spectral features of an AB diblock copolymer composed of polystyrene and a poly(1,2 & 3,4)isoprene‐based polymer with a pendant liquid crystalline 4‐cyanophenylazobenzene (Az) group in comparison with those of a corresponding LC polyisoprene homopolymer are reported. The orientational and photochromic behavior of an AB diblock copolymer in thin films shows distinct differences from that of a corresponding Az homopolymer. This can be attributed to the influence of the phase separated polymer coil microdomain of polystyrene in the AB block copolymer film. 相似文献
699.
Junde Wei Mengmeng Zhu Ben Liu Nan Wang Jieyi Liu Keiichi Tomishige Sibao Liu Guozhu Liu 《Angewandte Chemie (International ed. in English)》2023,62(46):e202310505
To address the global plastic pollution issues and the challenges of hydrogen storage and transportation, we report a system, based on the hydrodeoxygenation (HDO) of oxygen-containing aromatic plastic wastes, from which organic hydrogen carriers (LOHCs) can be derived. We developed a catalytic system comprised of Ru-ReOx/SiO2+HZSM-5 for direct HDO of polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene oxide (PPO), and their mixtures, to cycloalkanes as LOHCs, with high yields up to 99 %, under mild reaction conditions. The theoretical hydrogen storage capacity reaches ca. 5.74 wt%. The reaction pathway involves depolymerization of PC into C15 aromatics and C15 monophenols by direct hydrogenolysis of the C−O bond between the benzene ring and ester group, and subsequent parallel hydrogenation of C15 aromatics and HDO of C15 monophenols. HDO of cyclic alcohol is the rate-determining step. The active site is Ru metallic nanoparticles with partially covered ReOx species. The excellent performance is attributed to the synergetic effect of oxophilic ReOx species and Ru metallic sites for C−O hydrogenolysis and hydrogenation, and the promotion effect of HZSM-5 for dehydration of cyclic alcohol. The highly efficient and stable dehydrogenation of cycloalkanes over Pt/γ-Al2O3 confirms that HDO products can act as LOHCs. 相似文献
700.