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The preparation of polymer microcapsules of well defined size in the range of 10–50 μm with different shell thickness to
core diameter ratios is described. An aerosol of monodisperse droplets of a homogeneous ternary liquid system which contained
a hydrophobic component and a hydrophilic component dissolved in a high-volatile mutual solvent, was produced by dispersing
with a vibrating-orifice aerosol generator. After the evaporation of the solvent in a nitrogen atmosphere the particles demix
and form a two-phase droplet of core-shell type. These droplets were illuminated with UV light and polymerized to highly monodisperse
microcapsules with a solid polymer shell and a liquid core. The properties of the resulting particles (size, size distribution,
shell thickness, shape and surface characteristics) were investigated by scanning electron microscopy, Raman spectroscopy
on single optically levitated particles, and confocal Raman micro spectroscopy. The microcapsules were highly monodisperse
and have spherical shape.
Received: 24 July 1996 Accepted: 29 August 1996 相似文献
44.
A novel PBI/P84 co-polyimide dual-layer hollow fiber membrane has been specifically fabricated through the dry-jet wet phase inversion process, for the first time, for the dehydration pervaporation of tetrafluoropropanol (TFP). Polybenzimidazole (PBI) was chosen as the outer selective layer because of its superior hydrophilic nature and excellent solvent-resistance together with robust thermal stability, while P84 co-polyimide was employed as the inner supporting layer because of its good solvent-resistance and thermal stability. The PBI/P84 membrane exhibits superior water selectivity and relatively high permeation flux. At 60 °C, the PBI/P84 dual-layer hollow fiber membrane shows a permeation flux of 332 g/(m2 h) and a separation factor of 1990 for a feed solution containing of 85 wt% TFP. The preferential water sorption and the significant diffusivity difference between TFP and water are the main causes of high separation factor. However, an increase in feed temperature will greatly increase the permeation flux but seriously decrease the water selectivity. The activation energy data verify that water can preferentially permeate the PBI membrane due to the strong water affinity of PBI and a much smaller molecular size of water. 相似文献
45.
Ya Wen TANG Shuang CAO Ling Ling ZHANG Jian Chun BAO Ping ZHOU Tian Hong LU 《中国化学快报》2006,17(12):1623-1626
The performance of the direct formic acid fuel cell (DFAFC) is considerably higher than the direct methanol fuel cell (DMFC) because of some characteristics of formic acid1. For example, formic acid is non-toxic. Formic acid has two orders of magnitude smaller crossover flux through a Nafion membrane than methanol2. In DFAFC, the concentration of formic acid can be as high as 20 mol/L, while the best concentration of methanol in DMFC is only about 2 mol/L3. Thus, the power density of … 相似文献
46.
Xiao‐Hong Fu 《Electroanalysis》2007,19(17):1831-1839
A new electrochemical immunosensor for the detection of carbohydrate antigen‐125 (CA125), a carcinoma antigen, was developed by immobilization CA125 antibody (anti‐CA125) on gold hollow microspheres and porous polythionine (PTH) modified glassy carbon electrodes (GCE). The gold hollow microspheres provided a biocompatible microenvironment for proteins, and greatly amplified the coverage of anti‐CA125 molecules on the electrode surface. The performance and factors influencing the immunosensor were investigated in detail. The detection is based on the current change before and after the antigen‐antibody interaction. Under optimal conditions, the amperometric changes were proportional to CA125 concentration ranging from 4.5 to 36.5 U/mL with a detection limit of 1.3 U/mL (at 3σ). The CA125 immunosensor exhibited good precision, high sensitivity, acceptable stability, accuracy and reproducibility. The as‐prepared immunosensors were used to analyze CA125 in human serum specimens. Analytical results suggest that the developed immunoassay has a promising alternative approach for detecting CA125 in the clinical diagnosis. 相似文献
47.
Development of hollow fiber‐supported liquid‐phase microextraction and HPLC‐DAD method for the determination of pyrethroid metabolites in human and rat urine
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Wielgomas Bartosz Wiśniewski Marcin Czarnowski Wojciech 《Biomedical chromatography : BMC》2014,28(5):708-716
A simple hollow fiber liquid‐phase microextraction method for the determination of synthetic pyrethroid metabolites, 3‐phenoxybenzoic acid and 4‐hydroxy‐3‐phenoxybenzoic acid, in human and rat urine was developed and validated. A polypropylene hollow fiber tightly fitted onto a Nylon rod and impregnated with organic solvent served as a disposable extraction device. Desorption of analytes was carried out in NaOH solution, analyzed further by gradient HPLC and diode array detection method. Important factors were identified using Taguchi OA16 (45) orthogonal array design and further optimized using univariate approach. The optimum method performance was observed when 1 mL of urine hydrolyzed with 0.2 mL of concentrated HCl was further supplemented with 100 mg of NaCl and extracted for 120 min into dihexyl ether immobilized in the pores of the hollow fiber. Metabolites were desorbed into 0.1 mL of 0.1 M NaOH for another 120 min. Limits of detection and quantitation of 15 and 50 ng/mL were obtained for both analytes. Relative standard deviations of 1.6–12.6% over the linear range (50–10,000 ng/mL, r > 0.9906) were observed. Intra‐ and inter‐day accuracies of the method ranged from 98.3 to 109.5% and from 93.3 to 110.9%, respectively. The optimized method was applied to the analysis of real urine samples collected from rats exposed orally to cypermethrin. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
48.
Gadolinium‐Decorated Silica Microspheres as Redox‐Responsive MRI Probes for Applications in Cell Therapy Follow‐Up
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Dr. Monica Muñoz Úbeda Dr. Fabio Carniato Dr. Valeria Catanzaro Sergio Padovan Dr. Cristina Grange Dr. Stefano Porta Dr. Carla Carrera Prof. Lorenzo Tei Dr. Giuseppe Digilio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7716-7720
The redox microenvironment within a cell graft can be considered as an indicator to assess whether the graft is metabolically active or hypoxic. We present a redox‐responsive MRI probe based on porous silica microparticles whose surface has been decorated with a Gd‐chelate through a disulphide bridge. Such microparticles are designed to be interspersed with therapeutic cells within a biocompatible hydrogel. The onset of reducing conditions within the hydrogel is paralleled by an increased clearance of Gd, that can be detected by MRI. 相似文献
49.
Saeed Nojavan Tayebeh Gorji Saied Saeed Hosseiny Davarani Amin Morteza-Najarian 《Analytica chimica acta》2014
There are numerous published reports about dispersive liquid phase microextraction of the wide range of substances, however, till now no broadly accepted systematic and purpose oriented selection of extraction solvent has been proposed. Most works deal with the optimization of available solvents without adequate pre-consideration of properness. In this study, it is tried to compare the performances of low- and high-density solvents at the same conditions by means of novel type of extraction vessel with head and bottom conical shape. Extraction efficiencies of seven basic pharmaceutical compounds using eighteen common organic solvents were studied in this work. It was much easier to work with high-density solvents and they mostly showed better performances. This work shows that although exact predicting the performance of the solvents is multifaceted case but the pre-consideration of initial selection of solvents with attention to the physiochemical properties of the desired analytes is feasible and promising. Finally, the practicality of the method for extraction from urine and plasma samples was investigated. 相似文献