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991.
To exploit the photoluminescent behavior of CdS at nanoscale with different doping concentration of europium—a rare earth element, we report the synthesis of Eu-doped CdS nanorods by using low temperature solvothermal process by using ethylenediamine. The outcomes can have future applications as phosphors, photovoltaic cells, lasers, light emitting diodes, bio-imaging, and sensors. The doping was confirmed by electron dispersive spectroscopy supported by X-ray diffraction. From scanning electron microscopy and transmission electron microscopy analysis it was observed that the average diameter of the Cd1−x Eu x S nanorods is about 10–12 nm having lengths in the range of 50–100 nm. UV–Visible spectroscopy study was carried out to determine the band gap of the nanorods and the absorbance peaks showed blue shift with respect to the bulk CdS. The blue shift was also observed as the doping concentration of Eu increases. From photoluminescence (PL) studies at λex = 450 nm, peaks at 528 and 540 nm were observed due to CdS, peak at 570 nm is due to defects related transitions, while the peak at 613 nm is due to Eu. As the doping concentration of Eu is increased the intensity of the luminescent peak at 613 nm is increased. Thermogravimetric analysis showed the nanorods are thermally stable up to 300 °C. The traces of impurities adsorbed on the nanorods were confirmed by Fourier transform infrared spectroscopy.  相似文献   
992.
Origin of flow asymmetry in planar nozzles with separation   总被引:1,自引:0,他引:1  
An experimental investigation was conducted to study the mechanisms that lead to the origin of flow asymmetry in overexpanded planar nozzles, especially at low nozzle pressure ratios. Three Mach 2 planar nozzles with different divergent wall angles but same area-ratio were tested. For all three nozzles, a large portion of the dimensional pressure rise data across the separation shock shows the nature of boundary layer to be in the laminar/transitional state. Depending upon the local flow conditions, the flow can, therefore, experience either an early or a delayed separation on either wall. This can result in a free or a restricted shock separation condition on either wall which can initiate the beginning of flow asymmetry in nozzles at low nozzle pressure ratio. However, a higher nozzle wall angle was observed to prevent initiation of such a flow asymmetry. The present tests, therefore, indicate that in addition to the state of the boundary layer along the nozzle wall, the proximity of the separated shear layer to the nozzle walls also seems to play a dominant role in initiating conditions that favor the origin of flow asymmetry in nozzles. A significant drop in the shock unsteadiness levels was also indicated by increasing the wall angle.  相似文献   
993.
A tandem approach for the synthesis of fused naphthyridines and isoquinolines via preferential regio- and stereoselective addition of indoles/pyrroles onto o-haloarylalkynes over N-arylation is described. Inexpensive hydroxymethyl benzotriazole has been used as ligand under microwave irradiation. The structure of the product was confirmed by the X-ray crystallographic studies.  相似文献   
994.
Operando X‐ray absorption experiments and density functional theory (DFT) calculations are reported that elucidate the role of copper redox chemistry in the selective catalytic reduction (SCR) of NO over Cu‐exchanged SSZ‐13. Catalysts prepared to contain only isolated, exchanged CuII ions evidence both CuII and CuI ions under standard SCR conditions at 473 K. Reactant cutoff experiments show that NO and NH3 together are necessary for CuII reduction to CuI. DFT calculations show that NO‐assisted NH3 dissociation is both energetically favorable and accounts for the observed CuII reduction. The calculations predict in situ generation of Brønsted sites proximal to CuI upon reduction, which we quantify in separate titration experiments. Both NO and O2 are necessary for oxidation of CuI to CuII, which DFT suggests to occur by a NO2 intermediate. Reaction of Cu‐bound NO2 with proximal NH4+ completes the catalytic cycle. N2 is produced in both reduction and oxidation half‐cycles.  相似文献   
995.
In the recent article, Darwish and Odah (2010) develop a scheme that allows for identical replenishment cycles for all the retailers, in the context of a single vendor supplying a group of retailers under VMI partnership. This paper proposes an alternative replenishment scheme allowing for different replenishment cycles for each retailer. An example has been shown to illustrate the cost savings under the proposed model.  相似文献   
996.
Under certain conditions on the coefficients, we derive asymptotic formulas for the number of representations of zero and of large positive integers by the cubic forms that can be written as $L_{1}(x_{1},x_{2},x_{3}) Q_{1}(x_{1},x_{2},x_{3})+ L_{2}(x_{4},x_{5},x_{6}) Q_{2}(x_{4},x_{5}, x_{6}) + a_{7} x_{7}^{3}$ , where L 1 and L 2 are linear forms, Q 1 and Q 2 are quadratic forms, and a 7 is a nonzero integer.  相似文献   
997.
Epithelial tissue lining the inner side of the urinary bladder is the most common target for bladder cancer-related diseases. Bladders of freshly slaughtered pigs were utilised for a comprehensive analysis of the proteome and phosphoproteome of bladder epithelial cells. Following protein separation by 2-D gel electrophoresis and identification by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) the first proteome and phosphoproteome maps of pig urinary bladder epithelial cells (PUBEC) were established. A total of 120 selected protein spots were identified. By using the La(3+) enrichment method further developed in our laboratory we identified 31 phosphoproteins with minimal contamination by non-phosphopeptides. The 2-DE map of pig urothelial cells may prove as a useful tool for studies on uroepithelial biology, and the analysed phosphoproteins expression pattern, together with the whole cell proteome, will be helpful for identifying the proteins involved in bladder-related diseases.  相似文献   
998.
999.
Herein, design and synthesis of ternary gold nanoparticles@ sulfourea‐functionalized reduced graphene oxide (Gold‐NPs@SFG) is reported. It involves interaction of ‘sulfourea’ to the graphene sheets via amidation of edged carboxyls of graphene oxide with N‐terminals of sulfourea followed by association of Gold‐NPs. Sulfourea not only reduced the graphene oxide but interestingly, it is functionalized to graphene sheets via carbodiimide covalent junctions, which gives it local effect to increase the active surface area and excellent electrocatalytic properties. The prepared nanocomposite was characterized with SEM, TEM, FTIR, Raman, XRD, XPS and CV. Gold‐NPs@SFG was found to be more efficient electrocatalyst for the electrocatalytic oxidation of a drug ‘Acetaminophen’ using differential pulse voltammetry and it was employed as a highly sensitive and selective electrochemical sensor for the quantification of ‘Acetaminophen’ with the detection limit of 0.09 μM in the wide linear range of 1.2 to 300 μM.  相似文献   
1000.
An expeditious straightforward synthesis of sesquiterpene-cored arenes functionalized with electron-withdrawing or electron-donating substituents is described and illustrated by Michael addition of S-(−)-citronellal on functionalized 2H-pyran-2-one in a single step at room temperature. The reaction was further generalized by synthesizing isoprenylated 9,10-dihydrophenanthrene-2-carbonitrile using 5,6-dihydro-2-oxo-4-sec-amino-2H-benzo[h]chromene-3-carbonitriles and S-(−)-citronellal under similar reaction conditions.  相似文献   
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