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101.
The historical background of and the incentive for using ruthenium carbonyl clusters as homogeneous catalysts are outlined.
Keeping in view the possible solutions the uncertainties arising from declusterification and metal colloid formation are discussed.
All ruthenium cluster-catalysed reactions are broadly classified as reactions with or without carbon monoxide as one of the
reactants and the basic differences between such reactions are highlighted. Some of the factors of special relevance to cluster-catalysed
reaction systems are mentioned. The reactions involving carbon monoxide are then discussed. These include water-gas-shift
reaction, carbon monoxide hydrogenation, hydroformylation, reductive carbonylation of nitrobenzene and other carbonylation
reactions. Hydrogenation, transfer hydrogenation, isomerisation and a few other reactions are then discussed. For all these
reactions, special emphasis is laid on well-characterised cluster complexes that have been proposed as catalytic intermediates.
Finally an attempt has been made to identify the path that future research in cluster catalysis is likely to follow. 相似文献
102.
The oxidation of glycolic, lactic, malic, and a few substituted mandelic acids by 2,2′‐bipyridinium chlorochromate (BPCC) in dimethylsulphoxide leads to the formation of corresponding oxoacids. The reaction is first order each in BPCC and the hydroxy acids. The reaction is catalyzed by the hydrogen ions. The hydrogen ion dependence has the form: kobs = a + b [H+]. The oxidation of α‐deuteriomandelic acid exhibited a substantial primary kinetic isotope effect (kH/kd = 5.29 at 303 K). Oxidation of p‐methylmandelic acid was studied in 19 different organic solvents. The solvent effect has been analyzed by using Kamlet's and Swain's multiparametric equations. A mechanism involving a hydride ion transfer via a chromate ester is proposed. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 248–254, 2002 相似文献
103.
Effects of nutrients and temperature on lipid and fatty acid production in the diatomHantzshia DI-60
Sriharan Shobha bagga Davinderjit Sriharan T. P. 《Applied biochemistry and biotechnology》1990,24(1):309-316
Applied Biochemistry and Biotechnology - The ability of microalgae to accumulate considerable amounts of lipids has led to an increase in research on the cultivation of these organisms for the... 相似文献
104.
Eng William Palumbo Anthony V. Sriharan Shobha Strandberg G. W. 《Applied biochemistry and biotechnology》1991,(1):887-899
The effect of methanol on trichloroethylene (TCE) degradation by mixed and pure methylotrophic cultures was examined in batch
culture experiments. Methanol was found to relieve growth inhibition ofMethylosinus trichosporium (OB3b) at high (14 mg/L) TCE concentrations. Degradation of TCE was determined by both radiolabeling and gas chromatography
techniques. When cultures were grown on methanol over 10 to 14 d with 0.3 mg/L TCE, OB3b degraded 16.89 ±0.82% (mean± SD)
of the TCE, and a mixed culture (DT type II) degraded 4.55±0.11%. Mixed culture (JS type I) degraded 4.34±0.06% of the TCE.
When grown on methane with 0.3 mg/L TCE, 32.93±2.01% of the TCE was degraded by OB3b, whereas the JS culture degraded 24.3
±1.38% of the TCE, and the DT culture degraded 34.3 ±2.97% of the TCE. The addition of methanol to cultures grown on methane
reduced TCE degradation to 16.21 ±1.17% for OB3b and to 5.08±0.56% for JS. Although methanol reduces the toxicity of TCE to
the cultures, biodegradation of TCE cannot be sustained in methanol-grown cultures. Since high TCE concentrations appear to
inhibit methane uptake and growth, we suggest the primary toxicity of TCE is directed towards the methane monooxygenase. 相似文献
105.
106.
107.
Fulton R Jensen T Johnson DR Kagan H Kass R Morrow F Whitmore J Wilson P Bortoletto D Chen W Dominick J McIlwain RL Miller DH Ng CR Schaffner SF Shibata EI Shipsey IP Yao W Battle M Sparks K Thorndike EH Wang C Alam MS Kim IJ Li WC Romero V Sun CR Wang P Zoeller MM Goldberg M Haupt T Horwitz N Jain V Mestayer MD Moneti GC Rozen Y Rubin P Sharma V Skwarnicki T Thulasidas M Zhu G Csorna SE Letson T Alexander J Artuso M Bebek C Berkelman K Browder T Cassel DG Cheu E Coffman DM Crawford G DeWire JW 《Physical review D: Particles and fields》1991,43(3):651-663
108.
Pentafluoropyridine has been analysed in the frequency range of 8 to 18 GHz at dry ice temperature, using a conventional 100 kHz Stark modulated microwave spectrometer. The rotational constants and centrifugal distortion constants are A = 1481.539 ± 0.003 MHz, B = 1075.348 ± 0.004 MHz and C = 623.101 ± 0.001 MHz; and dJ = ?0.39 ± 0.06 kHz, dJK = 1.86 ± 0.27 kHz, dK = 0.70 ± 0.1 kHz, dEJ = (0.3 ± 0.03) × 10?6 and dEK = (?1.5 ± 0.2) × 10?6. The electric dipole moment has been found to be 0.98 ± 0.08 D and the values of the quadrupole coupling constants are xaa = 1.94 ± 0.22 MHz, xbb = ?4.08 ± 0.06 MHz and xcc = 2.14 ± 0.22 MHz. A simple analysis based on Townes and Dailey theory points to a considerable increase in the π-electron density and excess charge on the nitrogen site. 相似文献
109.
A systematic quantum mechanical study of the possible conformations, their relative stabilities, vibrational and electronic
spectra and thermodynamic parameters of methyl-3-methoxy-2-propenoate has been reported for the electronic ground (S0) and first excited (S1) states using time-dependent and time-independent Density Functional Theory (DFT) and RHF methods in extended basis sets.
Detailed studies have been restricted to the E-isomer, which is found to be substantially more stable than the Z-isomer. Four
possible conformers c′Cc, c′Tc, t′Cc, t′Tc, of which the first two are most stable, have been identified in the S0 and S1 states. Electronic excitation to S1 state is accompanied with a reversal in the relative stability of the c′Cc and c′Tc conformers and a substantial reduction
in the rotational barrier between them, as compared with the S0 state. Optimized geometries of these conformers in the S0 and S1 states are being reported. Based on suitably scaled RHF/6-31G** and DFT/6-311G** calculations, assignments have been provided to the fundamental vibrational bands of both these conformers in terms of frequency,
form and intensity of vibrations and potential energy distribution across the symmetry coordinates in the S0 state. A complete interpretation of the electronic spectra of the conformers has been provided. 相似文献
110.
A series of compositions with the general formula RE2Hf2O7 (RE=Dy, Ho, Er, Tm, Y and Lu) was prepared by a standard solid-state route and characterized by powder X-ray diffraction (XRD) and Raman spectroscopy. As per theoretical modeling reported in literature, some of these materials were predicted to exist in pyrochlore lattice. However, a careful X-ray diffraction, Raman spectroscopic and synchrotron radiation-XRD study revealed that under the experimental conditions used in the present investigation, out of all the RE2Hf2O7 samples only Dy2Hf2O7 has got a tendency to form a pyrochlore structure. All the other (Ho, Er, Tm, Lu, Y) hafnates crystallize in a defect-fluorite structure. In order to further ascertain these inferences, a few more RE2Hf2O7 samples (La, Nd, Sm) i.e., with larger RE3+ ions were also prepared and the results were compared. 相似文献