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991.
The influence of nine small organic molecules on the phosphorescence properties of β-cyclodextrin (β-CD)/1-naphthol/1,2-dibromoethane (DBE) and β-CD/2-naphthol/DBE ternary inclusion complexes are examined by means of room temperature phosphorescence (RTP) measurements. It was demonstrated that the rigidity of β-CD/naphthol inclusion complex, RTP intensity and lifetime could be enhanced when different small organic molecules (less than 1% v/v) were added respectively; the analytical characters of two kinds of naphthols in host-guest stabilized-RTP were improved. The linear range of 1-naphthol become broad in the presence of n-propanol, methanol, ethanol or 2-propanol and its detection limit was reduced from 4×10−6 to 7.5×10−8 mol l−1 in the presence of 0.6% (v/v) methanol. Likewise, for 2-naphthol, the detection limit was reduced from 2.0×10−6 to 2.8×10−7 mol l−1 and to 8.1×10−7 mol l−1 after 0.5% (v/v) glycol and 0.2% (v/v) 2-propanol being added, respectively. 相似文献
992.
Derivative spectrophotometric determination of praseodymium in rare earth mixtures with lomefloxacin
Praseodymium forms a Pr(LMFX)(3) complex with lomefloxacin. In this paper, the absorption spectra of the complex has been investigated by applying conventional and derivative spectrophotometric methods. It was found that lomefloxacin could form a stable complex with praseodymium in the pH 6.5-8.5 media. The absorption intensity of the complex is 4.5-fold more than PrCl(3). Using the second derivative spectra, the sensitivity is 7.4 times higher for Pr than in the normal method (zero derivative spectra). The second derivative spectrophotometry for determination of praseodymium in the presence of other rare earths has been developed. The calibration curves were linear in the range of 3.5-65 mug ml(-1) for Pr. The detection limit is 0.85 mug ml(-1). The method is satisfactory for the determination of praseodymium in mixed rare earths. 相似文献
993.
敌鼠钠盐—TritonX—100荧光光度法测定铕 总被引:2,自引:0,他引:2
敌鼠是一种广泛应用的高效抗凝血类杀鼠剂,其化学名称为2-(2,2-二苯基乙酰基)-1,3-茚满二酮,结构式为: 相似文献
994.
995.
996.
997.
7,7,8,8-四氰基对苯醌二甲烷(TCNQ)的CT复合物是良好的导电材料,具有许多超常的特性,我们曾用表面光电压技术(SPV)首次观察到TCNQ多晶内部既有施主基团又有受主基团,TCNQ与探针分子(CO,O_2,No_2)作用,其光电压谱发生2类不同的变化。为从理论上阐明产生不同光电压谱的原因,本文用CNDO法研究了TCNQ的电子结构及其与探针分子的相互作用,讨论了气敏特性与机理。 相似文献
998.
999.
Zheng Y Orbulescu J Ji X Andreopoulos FM Pham SM Leblanc RM 《Journal of the American Chemical Society》2003,125(9):2680-2686
Monolayers of several peptide lipids at air-water and air-solid interfaces were prepared using Langmuir and Langmuir-Blodgett (LB) film techniques, and tested as fluorescent sensors for copper ions in aqueous phase. In one method, both the ionophore and the fluorophore were in the same molecule (lipid A), so intramolecular interaction was responsible for the fluorescence quenching of monolayers of this lipid. In the other method, ionophore and fluorophore were located on two different molecules (lipids B and C) so the intramolecular coupling does not exist; instead the fluorescence quenching was realized by a through-space interaction mechanism. Several experimental techniques, including pi-A isotherm, epifluorescence microscopy, and absorption and emission spectroscopies were used to study the different characteristics of copper ion effect on the properties of the lipid monolayers. Additionally, the fluorescence quenching properties of the Langmuir monolayers were found to be transferred to the one-layer LB films. On LB films, the fluorescence response presented a clear selectivity for copper ions in comparison with several other transition metal ions. Further, an excellent reversibility was observed: the fluorescence was switched OFF by immersing the solid substrate in copper ion solution and ON by washing with HCl solution. The intermolecular approach used here seems to be a very flexible and general method to design surface-oriented fluorescent sensors to meet different analytic purposes. 相似文献
1000.
A new lanthanide-sensitized luminescence system: europium–sparfloxacin–1,10-phenanthroline–sodium dodecyl sulfate has been discovered. The spectrofluorimetric properties of the system were studied. The effect of experimental conditions on the fluorescence intensity was defined. Under the optimum conditions, the fluorescence intensity of the system is a linear function of the concentration of europium in the range 5.0×10–9–1.0×10–6 mol L–1 and the detection limit is 1.0×10–10 mol L–1. The system was used for the determination of trace amounts of europium in rare earth samples with satisfactory results. 相似文献