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961.
962.
963.
Reduced viscosity polymer matrices for microchip electrophoresis of double-stranded DNA 总被引:1,自引:0,他引:1
On a polymethylmethacrylate (PMMA) microchip, double-stranded DNA fragments with a wide size range from 50 bp to 20 kbp were separated by two polymer solutions. One was a hydroxypropylmethylcellulose-4000 (HPMC-4000) solution of 1.3% (w/v) to separate fragments below 590 bp, and another was a mixed four molecular weight poly(ethylene oxide) solution at a total concentration of 0.1% to separate fragments above 520 bp. The widths at half height (wh) of the fragments had a good relationship with their migration times (tR) in both polymer solutions. Such a relationship was suitable for obtaining the wh values of unresolved peaks, calculating the resolution of two adjacent fragments, and optimizing microchip separation matrices. Based on the relativity, a low viscosity medium containing 2% HPMC-50 and 8% glucose was optimized for high-performance separation of a phiX174 HaeIII restriction fragment digest. 相似文献
964.
A novel carrier of ultradispersed diamond black powder (UDDBP) was used to support metallocene catalyst. Al2O3 was also used as carrier in order to compare with UDDBP. Supported catalysts for ethylene polymerization were synthesized by two different reaction methods. One way was direct immobilization of the metallocene on the support, the other was adsorption of MAO onto the support followed by addition of the metallocene. Four supported catalysts Cp2ZrCl2/UDDBP, Cp2ZrCl2/Al2O3, Cp2ZrCl2/MAO/UDDBP and Cp2ZrCl2/Al2O3/MAO were obtained. The content of the zirconium in the supported catalyst was determined by UV spectroscopy. The activity of the ethylene polymerization catalyzed by supported catalyst was investigated. The influence of Al/Zr molar ratio and polymerization temperature on the activity was discussed. The polymerization rate was also observed. 相似文献
965.
Yao‐Cheng Shi Bei‐Bei Zhu Xiao‐Bi Jing 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(11):m559-m562
The molecules of N,N′‐bis(2‐pyridylmethyl)ferrocene‐1,1′‐diyldicarboxamide, [Fe(C12H11N2O)2], contain intramolecular N—H⋯N hydrogen bonds and are linked into sheets by three independent C—H⋯O hydrogen bonds. The molecules of the isomeric compound N,N′‐bis(3‐pyridylmethyl)ferrocene‐1,1′‐diyldicarboxamide lie across inversion centres, and the molecules are linked into sheets by a combination of N—H⋯N hydrogen bonds and π–π stacking interactions between pyridyl groups. 相似文献
966.
Thermochemistry of the solid complex Gd(Et<Subscript>2</Subscript>dtc)<Subscript>3</Subscript>(phen)
Summary A ternary solid complex Gd(Et2dtc)3(phen) has been obtained from reactions of sodium diethyldithiocarbamate (NaEt2dtc), 1,10-phenanthroline (phen) and hydrated gadolinium chloride in absolute ethanol. The title complex was described by chemical and elemental analyses, TG-DTG and IR spectrum. The enthalpy change of liquid-phase reaction of formation of the complex, ΔrHΘm(l), was determined as (-11.628±0.0204) kJ mol-1 at 298.15 K by a RD-496 III heat conduction microcalorimeter. The enthalpy change of the solid-phase reaction of formation of the complex, ΔrHΘm(s), was calculated as (145.306±0.519) kJ mol-1 on the basis of a designed thermochemical cycle. The thermodynamics of reaction of formation of the complex was investigated by changing the temperature of liquid-phase reaction. Fundamental parameters, the apparent reaction rate constant (k), the apparent activation energy (E), the pre-exponential constant (A), the reaction order (n), the activation enthalpy (ΔrHΘ≠), the activation entropy (ΔrSΘ≠), the activation free energy (ΔrGΘ≠) and the enthalpy (ΔrHΘ≠), were obtained by combination of the thermodynamic and kinetic equations for the reaction with the data of thermokinetic experiments. The constant-volume combustion energy of the complex, ΔcU, was determined as (-18673.71±8.15) kJ mol-1 by a RBC-II rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, ΔcHΘm, and standard enthalpy of formation, ΔfHΘm, were calculated to be (-18692.92±8.15) kJ mol-1 and (-51.28±9.17) kJ mol-1, respectively. 相似文献
967.
Patterned polyelectrolyte multilayer: surface modification for enhancing selective adsorption 总被引:4,自引:0,他引:4
Shi F Wang Z Zhao N Zhang X 《Langmuir : the ACS journal of surfaces and colloids》2005,21(4):1599-1602
This paper describes the use of surface chemical modification to enhance the difference of the surface charge on a patterned polyelectrolyte multilayer, which can be used for selectively adsorbing functional materials. We fabricated a patterned multilayer by combining the layer-by-layer self-assembly technique and photolithography and taking advantage of the different solubility of polyelectrolyte multilayers of diazo resins (DAR)/poly(acrylic acid) before and after UV irradiation. This patterned surface can be used as a matrix for selective adsorption of small molecular dyes, such as Methylene Blue. However the difference in surface charge on the patterned surface was not enough when we used it to selectively adsorb polystyrene (PS) nanoparticles using electrostatic force as the driving force. Therefore, we modified the patterned surface by interfacial chemistry. After modification, the patterned polyelectrolyte multilayer can be used as a good matrix for selective adsorption of PS nanoparticles with both positive and negative charges. 相似文献
968.
Qi‐Wei Zhang Yi‐Hang Wen Yun‐Long Feng 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(6):m255-m257
The title compound, [Zn2(C5H6O4)2(C13H14N2)]n or [Zn2(glu)2(bpp)]n, is a novel zinc polymer based on mixed flexible glutarate (glu) and 1,3‐di‐4‐pyridylpropane (bpp) ligands. The ZnII center has a distorted tetrahedral geometry and the central atom of the bpp ligand is located at a special site with a C2 axis passing through it. A layer is formed by Zn–glu bonding. Such layers are pillared by bpp ligands, forming a three‐dimensional framework with large channels. The inverted interpenetration of two three‐dimensional frameworks completes the molecular structure. 相似文献
969.
Ya-Guang Chen Fan-Xia Meng Hai-Jun Pang Dong-Mei Shi Yu Sun 《Journal of Cluster Science》2007,18(2):396-405
A novel uranyl complex with dimeric lacunary polyoxoanion like open-mouthed clam, Na5[(A-α-SiW9O33H3)2K{UO2(H2O)}2], was prepared and characterized by elemental analysis, infrared and ultraviolet–visible spectroscopy and single crystal
X-ray diffraction. In the anion, two A-α-SiW9O3410− groups share two terminal oxygen atoms Od′ derived from removal of three corner-shared W atoms from saturated α-Keggin anion, forming a dimeric anion with an open
mouth in which potassium ion and uranyl ions are coordinated. Uranium atom adopts a pentagonal bipyramidal geometry. The coordinating
anions are linked by sodium ions via coordination of terminal or bridging oxygen atoms, forming two-dimensional layer arrangement.
Between the layers are the hydrogen bonds from which a supramolecular architecture is created. UV–VIS spectrum gives W–O and
U–O charge transfer transitions at 230–265 and 432 nm, showing the change of geometry of the polyanion and weakening of the
U–O bonds of the uranyl cation.
Electronic supplementary material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
970.
Yan Xiao Jian Wang Wang Xia Guang Feng Huai You Wang 《Journal of Analytical Chemistry》2007,62(5):438-443
The maximum emission wavelength of dopamine is 317 nm with excitation at 290 nm. The relative fluorescence intensity of dopamine
decreased in the presence of enoxacin, which showed that fluorescence quenching occurred. The Stern-Volmer (S-V) plot showed
a nonlinear relationship between the relative fluorescence intensity of dopamine and the concentration of enoxain. The quenching
mechanism was studied and the results suggested that both dynamic and static quenching processes were responsible for the
observed positive deviation in the S-V plot. When the S-V plot was modified by logarithm, the linear relationship was obtained
between logF
0/F and C in the range of 0.10 to 13.0 μg/mL (where F
0 is the relative fluorescence intensity of dopamine, F is the relative fluorescence intensity of dopamine in the presence of enoxacin, and C is the concentration of enoxacin). The fluorescence quenching method for the determination of enoxacin was developed. The
linear regression equation of the calibration graph of enoxacin was C = 13.70 (logF
0/F) − 0.5836, with the correlation coefficient 0.9984. The detection limit was 2.0 ng/mL and the relative standard deviation
was 2.52%. The effects of pH, the stability of dopamine in the presence of enoxacin, and foreign ions on the determination
of enoxacin have been examined. The recovery of enoxacin was from 94.9 to 103.0% in a human serum sample and from 94.9 to
108.0% in a urine sample. The method is simple, rapid, and can be used for the determination of enoxacin in human serum and
urine samples with satisfactory results.
The text was submitted by the authors in English. 相似文献