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81.
Fluorine substituted Li1.27Cr0.2Mn0.53O2 electrode, prepared by sol–gel method, was investigated in the present work. Thermal analysis was done on this cathode material
and found to be thermally stable with a loss of weight near 300 °C. Influence of fluorine substitution on the structural and
electrochemical properties of the Li1.27Cr0.2Mn0.53O2 electrode was studied by X-ray diffraction (XRD) and field emission scanning electron microscope. XRD pattern of the fluorine-doped
Li1.27Cr0.2Mn0.53O2 cathode material quenched at 900 °C indicates a phase pure material. The charge–discharge profile of the prepared cathode
material showed that the fluorine substitution for oxygen in the cathode material resulted in improved capacity retention.
Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, December 7–9,
2006. 相似文献
82.
Chetan R. Singh Gaurav Gupta Ruth Lohwasser Sebastian Engmann Jens Balko Mukundan Thelakkat Thomas Thurn‐Albrecht Harald Hoppe 《Journal of Polymer Science.Polymer Physics》2013,51(12):943-951
A series of well‐defined poly(3‐hexylthiophene)s (P3HT) of different molecular weight (MW) and high regioregularity was investigated for charge transport properties in as‐cast and melt‐crystallized films. The semicrystalline structure of the P3HT was characterized by X‐ray scattering and Atomic force microscopy. Crystallization by cooling from the melt led to a substantial increase in crystallinity and a stronger alignment of the crystals in comparison to as‐cast films. The increase in crystallinity went along with an increase in hole mobility of up to an order of magnitude as measured by the space charge limited current method. Additionally, the hole mobility depended on the long period of P3HT lamellae and consequently on the MW. In compliance with the long period, the charge carrier mobility first increased with the MW before decreasing again at the onset of chain folding. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 943–951 相似文献
83.
The chromatographic behaviour of a recombinant human antibody (IgG1-subtype, κ-light chain, MW: 149.5 kD, pI: 9.3) was investigated as a function of the buffer pH and buffer type (HEPES, phosphate, borate) on fluoroapatite and hydroxyapatite stationary phases. HEPES buffer was used at pH 7.0, phosphate buffer at pH 8.2 and borate buffer between pH 8.5 and 11. Elution was by a double gradient method of first a salt gradient from 0 to 1 M NaCl in the corresponding buffer, followed by a step gradient to 0.4 M sodium phosphate. Regardless of the pH and buffer type, the antibody eluted in the NaCl gradient; capacity factors decreased with increasing pH. At pH 11 the antibody eluted in the flow-through. Retention was thus dominated by electrostatic interaction throughout the investigated pH-range. Investigation of antibody fragments obtained by papain digestion (fc- and fab-fragments) and deglycosylated fc-fragments showed that the sugar structures had no influence on the chromatographic behaviour. Instead the chromatographic behaviour was dominated by that of the fab-fragment. ζ-Potential measurements verified that the apatite surface bore a negative surface charge in the investigated pH range, while the antibody net surface charge switched from positive to negative as the pH increased. The corresponding isoionic point was a function of both the buffer concentration and the buffer species. However, above a pH of 8.3 the ζ-potential of the antibody generally was negative. Simulations of the molecular electrostatic potential of the antibody and the two fragments revealed the presence of a positively charged patch within the fab-fragment, which only disappeared above a pH of 10. Most likely this patch was responsible for the observed behaviour. 相似文献
84.
85.
This study evaluates the potential use of stable zinc isotopes in toxicity studies measuring zinc uptake by the gills of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss). The use of stable isotopes in such studies has several advantages over the use of radioisotopes, including cost, ease of handling, elimination of permit requirements, and waste disposal. A pilot study using brown trout was performed to evaluate sample preparation methods and the ability of a quadrupole inductively coupled plasma mass spectrometer (ICP-MS) system to successfully measure changes in the 67Zn/66Zn ratios for planned exposure levels and duration. After completion of the pilot study, a full-scale zinc exposure study using rainbow trout was performed. The results of these studies indicate that there are several factors that affect the precision of the measured 67Zn/66Zn ratios in the sample digests, including variations in sample size, endogenous zinc levels, and zinc uptake rates by individual fish. However, since these factors were incorporated in the calculation of the total zinc accumulated by the gills during the exposures, the data obtained were adequate for their intended use in calculating zinc binding and evaluating the influences of differences in water quality parameters. 相似文献
86.
Ruth Müller Christian Wiencke Kai Bischof Bernd Krock 《Photochemistry and photobiology》2009,85(4):970-977
Phlorotannins have often been considered to act as UV-protective compounds in zoospores of brown algae. However, only the absorption characteristics of zoospores under UV exposure have been determined and no data are available on the actual content of phlorotannins or on temperature–UV interactions. Therefore, we determined the absorbance spectra and the phlorotannin contents in zoospore suspensions of three Arctic species ( Saccharina latissima , Laminaria digitata , Alaria esculenta ), and in the media surrounding zoospores after exposure to different radiation (400–700, 320–700, 295–700 nm) and temperature (2–18°C) conditions for 8 h. Absorption typical of phlorotannins with a maximum at 276 nm was monitored in zoospore suspensions as well as in the media surrounding zoospores, but the results depended strongly on radiation treatments and on zoospore densities. Surprisingly, the content of UV-absorbing phlorotannins subsequent to different exposures did not change in any of the three species. The observed exceptional absorption properties could, therefore, not be related to phlorotannin contents. These findings are discussed in light of a strong phlorotannin investment from sporophytes during spore release and a minor UV-protective role of phlorotannins for zoospores of Arctic kelp species. 相似文献
87.
The effect of microstructure on the rheology of clay/polymer nanocomposites is investigated using dispersions of organically
treated clay in nearly Newtonian poly(dimethylsiloxane). Degree of dispersion and floc size are altered by using two different
dispersion procedures and by changing the shear history. The scaling for dynamic moduli of attractive colloids applies, except
for a possible relaxation mechanism at very low frequencies. The time to reach the crossover at a given frequency is found
to be extremely sensitive to the dispersion procedure used. Hydrodynamic and elastic components of the steady state stress,
on the other hand, evolve in a very similar fashion for the different systems. Although the relaxation times of the elastic
stress components change drastically with flow-induced changes in structure, the dispersion process hardly has an effect at
all. Intermittent start-up flows in the forward and reverse directions show that anisotropy persists long after the flow has
been arrested, even at shear rates where no large reversible flocs are present. The degree of dispersion only had a limited
effect on the anisotropy. Finally, the effect of shear on structure recovery has been studied. Very low shear rates are found
to increase the rate of recovery, even for small strains. 相似文献
88.
The use of municipal solid waste (MSW) compost as a sorbent for tributyltin (TBT) in seawater was investigated. TBT‐contaminated seawater, both artificially prepared and that collected from Msida Creek yacht marina (Malta), was allowed to percolate through untreated and water‐washed columns of compost and then analysed for organotins using gas chromatography‐flame photometric detection. About 90% of dissolved TBT ranging in concentration from about 800 to 8000 ngSnl?1 was sorbed by treating 500 ml solutions with 100 g untreated compost. On the other hand, no detectable breakthrough of TBT was observed from compost that had previously been washed by water to remove soluble organic matter. Breakthrough of TBT from unwashed compost is thought to be due to formation of complexes between the soluble organic matter in compost and aquated TBT, which renders the organotin more hydrophilic. The use of washed MSW compost as sorbent for the purification of TBT‐contaminated waters generated in large quantity during hull‐cleaning activities in drydocks is suggested as a mitigatory measure against the impact of TBT on the coastal marine environment. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
89.
90.