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131.
The apparent molar volume and apparent molar isentropic compressibility of solutions of sodium di-hydrogen phosphate (NaH2PO4) in (1-propanol + water) mixed-solvent media with alcohol mass fractions of 0.00, 0.05, 0.10, and 0.15 are reported over the range of temperature (283.15 to 303.15) K at 5 K intervals. The results were fitted to a Redlich–Mayer type equation from which the apparent molar volume and apparent molar isentropic compressibility of the solutions at the infinite dilution were also calculated at the working temperature. The results show a positive transfer volume of NaH2PO4 from an aqueous solution to an aqueous 1-propanol solution. The apparent molar isentropic compressibility of NaH2PO4 in aqueous 1-propanol solutions is negative and it increases with increasing the concentration of NaH2PO4, 1-propanol, and temperature. Electrical conductivity and refractive index of the solutions are also studied at T = 298.15 K. The effects of the electrolyte concentration and relative permittivity of the medium on the molar conductivity were also investigated. 相似文献
132.
Petr Michalek Simona Dostalova Hana Buchtelova Natalia Cernei Ludmila Krejcova David Hynek Vedran Milosavljevic Ana Maria Jimenez Jimenez Pavel Kopel Zbynek Heger Vojtech Adam 《Electrophoresis》2016,37(14):2025-2035
Annual epidemics of influenza cause death of hundreds of thousands people and they also have a significant economic impact. Hence, a need for fast and cheap influenza diagnostic method is arising. The conventional methods for an isolation of the viruses are time‐consuming and require expensive instrumentation as well as trained personnel. In this study, we modified the surface of nanomaghemite (γ‐Fe2O3) paramagnetic core with tetraethyl orthosilicate and (3‐aminopropyl)triethoxysilane and the resulting particles were utilized for the isolation of H7N7 influenza virions. Consequently, we designed γ‐Fe2O3 paramagnetic core modified with calcium tripolyphosphate which was employed for the isolation of viral nucleic acid after virion's lysis. Both of these procedures can be performed rapidly in less than 10 min and, in combination with the RT‐PCR, the whole influenza detection can be shortened to few hours. Moreover, the whole protocol could be easily automated and/or miniaturized, and thus can serve as a basis for use in a lab‐on‐a‐chip device. We assume that magnetic isolation is an exceptional procedure which can significantly accelerate the diagnostic possibilities of a broad spectrum of diseases. 相似文献
133.
Veronika Šolínová Hana Mikysková Martin Maxmilián Kaiser Zlatko Janeba Václav Kašička 《Electrophoresis》2016,37(2):239-247
Affinity capillary electrophoresis (ACE) has been applied to estimation of apparent binding constant of complexes of (R,S)‐enantiomers of selected acyclic nucleoside phosphonates (ANPs) with chiral selector β‐cyclodextrin (βCD) in aqueous alkaline medium. The noncovalent interactions of five pairs of (R,S)‐enantiomers of ANPs‐based antiviral drugs and their derivatives with βCD were investigated in the background electrolyte (BGE) composed of 35 or 50 mM sodium tetraborate, pH 10.0, and containing variable concentration (0–25 mM) of βCD. The apparent binding constants of the complexes of (R,S)‐enantiomers of ANPs with βCD were estimated from the dependence of effective electrophoretic mobilities of (R,S)‐enantiomers of ANPs (measured simultaneously by ACE at constant reference temperature 25°C inside the capillary) on the concentration of βCD in the BGE using different nonlinear and linear calculation methodologies. Nonlinear regression analysis provided more precise and accurate values of the binding constants and a higher correlation coefficient as compared to the regression analysis of the three linearized plots of the effective mobility dependence on βCD concentration in the BGE. The complexes of (R,S)‐enantiomers of ANPs with βCD have been found to be relatively weak – their apparent binding constants determined by the nonlinear regression analysis were in the range 13.3–46.4 L/mol whereas the values from the linearized plots spanned the interval 12.3–55.2 L/mol. 相似文献
134.
Ivana Šrámková Burkhard Horstkotte Hana Sklenářová Petr Solich Spas D. Kolev 《Analytica chimica acta》2016
A novel approach to the automation technique Lab-In-Syringe, also known as In-Syringe Analysis, is proposed which utilizes a secondary inlet into the syringe void, used as a size-adaptable reaction chamber, via a channel passing through the syringe piston. This innovative approach allows straightforward automation of head-space single-drop microextraction, involving accurately controlled drop formation and handling, and the possibility of on-drop analyte quantification. 相似文献
135.
136.
The electrochemical oxidative behavior of terbutaline at the glassy carbon electrode was studied in a series of the Britton-Robinson buffer of pH 2--11. Cyclic and square-wave voltammograms of terbutaline at the pH values =9 exhibited a single irreversible anodic peak. A fully validated, simple, sensitive and precise square-wave adsorptive anodic stripping voltammetric procedure was described for the determination of terbutaline in bulk form, tablets and human serum. For 5x10(-8) M bulk terbutaline a mean recovery of 98.78+/-0.94% (n=5) was achieved following its preconcentration by adsorptive accumulation onto the glassy carbon electrode at a +0.15 V (vs. Ag/AgCl/KCl(s)) for 180 s. Limit of detection of 6x10(-9) M and limit of quantitation of 2x10(-8) M terbutaline were achieved in the bulk form or its formulations (Bricanyl tablets). The described square-wave adsorption anodic stripping voltammetric procedure was successfully applied for the determination of terbutaline in human serum following medium exchange. Limit of detection of 1.41x10(-8) M (3.173 ng ml(-1)) and limit of quantitation of 4.70x10(-8) M (10.575 ng ml(-1)) were achieved in human serum with a mean recovery of 98.11+/-1.13%. 相似文献
137.
Lubo Fical Maria Khalikova Hana Ko
ov Vl
kov Ivona Lhotsk Zuzana Hadysov Ivan Vokl Luk ervený Frantiek vec Lucie Novkov 《Molecules (Basel, Switzerland)》2021,26(8)
Two new ultra-high performance liquid chromatography (UHPLC) methods for analyzing 21 selected antivirals and their metabolites were optimized, including sample preparation step, LC separation conditions, and tandem mass spectrometry detection. Micro-solid phase extraction in pipette tips was used to extract antivirals from the biological material of Hanks balanced salt medium of pH 7.4 and 6.5. These media were used in experiments to evaluate the membrane transport of antiviral drugs. Challenging diversity of physicochemical properties was overcome using combined sorbent composed of C18 and ion exchange moiety, which finally allowed to cover the whole range of tested antivirals. For separation, reversed-phase (RP) chromatography and hydrophilic interaction liquid chromatography (HILIC), were optimized using extensive screening of stationary and mobile phase combinations. Optimized RP-UHPLC separation was carried out using BEH Shield RP18 stationary phase and gradient elution with 25 mmol/L formic acid in acetonitrile and in water. HILIC separation was accomplished with a Cortecs HILIC column and gradient elution with 25 mmol/L ammonium formate pH 3 and acetonitrile. Tandem mass spectrometry (MS/MS) conditions were optimized in both chromatographic modes, but obtained results revealed only a little difference in parameters of capillary voltage and cone voltage. While RP-UHPLC-MS/MS exhibited superior separation selectivity, HILIC-UHPLC-MS/MS has shown substantially higher sensitivity of two orders of magnitude for many compounds. Method validation results indicated that HILIC mode was more suitable for multianalyte methods. Despite better separation selectivity achieved in RP-UHPLC-MS/MS, the matrix effects were noticed while using both chromatographic modes leading to signal enhancement in RP and signal suppression in HILIC. 相似文献
138.
139.
The attempted O-tosylation of tetracyclo[3.2.0.02,7.04,6]heptan-3-one (quadricyclanone) oxime with p-toluenesulfonyl chloride in dichloromethane in the presence of triethylamine/DMAP or pyridine resulted in the Beckmann fragmentation to give a mixture of 4-exo-/4-endo-tosyloxy- and 4-exo-/4-endo-chlorobicyclo[3.1.0]hex-2-ene-6-endo-carbonitriles in 90% overall yield. Solvolysis of all four products in 2,2,2-trifluoroethanol afforded the corresponding 4-exo-trifluoroethoxy derivative as the sole product. Quadricyclanone itself undergoes the fragmentation reaction with hydroxylamine-O-sulfonic acid, selectively affording the 4-exo-hydroxy-6-endo-nitrile in 90% isolated yield. 相似文献
140.
An efficient two-step synthetic pathway toward the preparation of diversely substituted 5-aroyl-3,4-dihydropyrimidin-2-ones is realized. The protocol involves an initial trimethylsilyl chloride-mediated Biginelli multicomponent reaction involving S-ethyl acetothioacetate, aromatic aldehydes, and ureas as building blocks to generate a set of 3,4-dihydropyrimidine-5-carboxylic acid thiol esters. These thiol esters serve as starting materials for a subsequent Pd-catalyzed Cu-mediated Liebeskind-Srogl cross-coupling reaction with boronic acids to provide the desired 5-aroyl-3,4-dihydropyrimidin-2-one derivatives. Both steps were performed using microwave heating in sealed vessels, either in an automated sequential or parallel format using dedicated microwave reactor instrumentation. A diverse library of 30 5-aroyl-3,4-dihydropyrimidin-2-ones was prepared with commercially available aldehyde, urea, and boronic acid building blocks as starting materials. 相似文献