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81.
Stacking of Benzene with Metal Chelates: Calculated CCSD(T)/CBS Interaction Energies and Potential‐Energy Curves 下载免费PDF全文
Dušan P. Malenov Dragan B. Ninković Dr. Dušan N. Sredojević Prof.Dr. Snežana D. Zarić 《Chemphyschem》2014,15(12):2458-2461
Accurate values for the energies of stacking interactions of nickel‐ and copper‐based six‐membered chelate rings with benzene are calculated at the CCSD(T)/CBS level. The results show that calculations made at the ωB97xD/def2‐TZVP level are in excellent agreement with CCSD(T)/CBS values. The energies of [Cu(C3H3O2)(HCO2)] and [Ni(C3H3O2)(HCO2)] chelates stacking with benzene are ?6.39 and ?4.77 kcal mol?1, respectively. Understanding these interactions might be important for materials with properties that are dependent on stacking interactions. 相似文献
82.
A sensitive square‐wave voltammetry method was developed to determine cholecalciferol (vitamin D3) in pharmaceutical products at boron‐doped diamond electrode as a working electrode. Vitamin D3 provided a well‐defined voltammetric peak at around +1.00 V (vs. Ag/AgCl, 3.5 mol dm?3) in 0.02 mol dm?3 Britton‐Robinson buffer pH 5.0 prepared in 50 % ethanol. The influence of various factors such as type and pH of the supporting electrolyte, scan rate and square‐wave parameters were studied and optimized. Under optimum conditions, the oxidation peak current increased linearly with the concentration of vitamin D3 over the range of 2 to 200 μmol dm?3. The calculated limit of detection and limit of quantitation were 0.17 μmol dm?3 and 0.51 μmol dm?3, respectively. The boron‐doped diamond electrode exhibited specific recognition capability for cholecalciferol amongst possible interferences, and the determination of vitamin D3 was possible in samples such as commercial pharmaceutical products without complicated sample pretreatments. 相似文献
83.
A combined study of2H nuclear magnetic resonance lineshape and spin-lattice and spin-spin relaxation times as functions of temperature and the amount of hydration water in a cross-linked copolymer of sucrose and 1,4-butadienol diglycidyl ether in the hydrogel phase is reported. The results show strong evidence that the onset of the relaxation mechanisms is driven by anomalous water molecule diffusion depending on both temperature and the hydration degree of the hydrogel. In addition, these results are correlated with the transitions observed by differential thermal analysis. 相似文献
84.
The theory of point estimation treating the initial conditions for the safe convergence of iterative processes for the simultaneous
determination of polynomial zeros is considered. A general approach which makes use of corrections appearing in iterative
formulas is given and demonstrated in the case of three well known methods without derivatives and based on Weierstrass’ corrections.
The established convergence conditions are of practical importance since they depend only on available data: coefficients
of a polynomial and initial approximations to the zeros.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
85.
Miljanić S Dijanošić A Piantanida I Meić Z Albelda MT Sornosa-Ten A García-Espana E 《The Analyst》2011,136(15):3185-3193
Raman and surface-enhanced Raman spectra of new DNA/RNA-binding compounds consisting of three imidazole (Im) and three pyridine (Py) rings connected by tripodal polyaminomethylene linkages were obtained by the near-infrared excitation at 1064 nm. Study of interactions of Im and Py polyamines with single-stranded RNA polynucleotides (poly?A, poly?G, poly?C, poly?U), double-stranded DNA polynucleotides (poly?dAdT-poly?dAdT, poly?dGdC-poly?dGdC) and calf thymus DNA (ct-DNA) by surface-enhanced Raman spectroscopy (SERS) reveals unambiguous enhancement of the Raman scattering from the small molecules as well as appearance of new bands in spectra associated mainly with nucleobases. The SERS experiments point toward comparable interactions of Im and Py polyamines with single-stranded purine and pyrimidine polynucleotides. Furthermore, SERS experiments with double stranded polynucleotides reveal the base-pair dependent selectivity of Im and Py, whereby interactions within both, major and minor groove are indicated for poly?dAdT-poly?dAdT, at variance to preferred binding of Im and Py to only major groove of poly?dGdC-poly?dGdC. SERS spectra of Im and Py with ct-DNA imply that protonated amino groups of these compounds preferentially interact with N7 atoms (adenine, guanine) while nitrogen in aromatic rings of polyamines might be attracted to C6-NH(2) (adenine), all sites being located at the major groove of the DNA helix. Wavenumber downshift of the imidazole (Im) and pyridine (Py) ring vibrations supports aromatic stacking interactions of imidazole and pyridine aromatic moieties with DNA base-pairs. 相似文献
86.
An analytical solution for the two-dimensional non-isothermal compressible gas flow in a slider microbearing is presented in this paper. The solutions enable analysis of the relevant parameters influences on the load carrying capacity of the micro-bearing. Hence, the influences of the flow conditions expressed by Mach, Reynolds and Knudsen numbers, the ratio of the inlet to outlet heights, bearing number, as well as temperature field are investigated. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
87.
Assaleh Mohamed H. Božić Aleksandra R. Bjelogrlić Snežana Milošević Milena Simić Milena Marinković Aleksandar D. Cvijetić Ilija N. 《Structural chemistry》2019,30(6):2447-2457
Structural Chemistry - Thiocarbohydrazones (TCHs) and structurally related molecules are versatile organic compounds which exert antioxidant, anticancer, and other beneficial health effects. The... 相似文献
88.
Carlos Ezquer‐Garin Rafael Ferriols‐Lisart Manuel Als‐Almiana 《Biomedical chromatography : BMC》2019,33(7)
Stability studies are necessary in healthcare settings as they facilitate fast, cost‐effective and efficient work related to batch manufacturing and availability of supplies. We studied the stability of 1–10 mg/mL mycophenolate mofetil (MMF) in polypropylene 5% dextrose infusion bags prepared from Cellcept® and with a generic brand name (Micofenolato de Mofetilo Accord) at different storage temperatures. To ensure chemical compatibility during preparation, we also tested MMF sorption to the Equashield® closed‐system drug transfer device used in this step. For this, a validated stability‐indicating high‐performance liquid chromatography method was developed for the quantification and identification of MMF in the infusion bags. The analytical selectivity of the assay was determined by subjecting an MMF sample to extreme values of pH, oxidative stress and heat conditions to force degradation. Protected from light, 1–10 mg/mL MMF in infusion polypropylene bags prepared from reconstituted Cellcept® 500 mg or Accord 500 mg in 5% dextrose was stable for at least 35 days when stored at 2–8°C or between ?15 and ?25°C, and for 14 days when stored at 25°C. MMF loss owing to chemical sorption to the Equashield® closed‐system drug transfer device set was negligible. 相似文献
89.
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