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91.
AbstractA new phenanthropyran, dioscorone B (1), and a new phenanthrene (2), together with seven known compounds (3–9), were isolated from the 75% ethanol extract of Dioscorea septemloba rhizomes. The chemical structures of these compounds were elucidated by comprehensive spectroscopic methods including NMR, HRESIMS, IR, and UV spectra. Compounds 1–5 were first isolated from genus Dioscorea. The proton and carbon chemical shifts of compounds 1–9 were unambiguously assigned based on the 1D-NMR and 2D-NMR data. Compounds 1–5 and 8–9 were first tested for their antioxidant activities. Compounds 1 and 2 showed excellent activities with IC50 values of 0.07?±?0.10?μM and 0.13?±?0.09?μM, respectively. 相似文献
92.
Yan-Hong Liu Tong-Lai Zhang Jian-Guo Zhang Li Yang Wen-Guang Yu Rui-Feng Wu Kai-Bei Yu 《Structural chemistry》2006,17(4):351-357
We reported in this study the synthesis, culture of crystal, and single-crystal X-ray crystallography of the 2,4,6-trinitro-trimethylbenzene (TNTM) compound. We found the crystal belongs to the Triclinic system with space group P-1. The compound was also characterized by FT-IR,1H NMR, and MS spectroscopy techniques. Density functional theory (DFT) B3LYP was employed to optimize structure and calculate frequencies of TNTM. The calculated geometrical parameters are close to the corresponding experimental ones. The thermal decomposition of TNTM was investigated by DSC and TG–DTG methods at heating rate 10°C/min. The results indicate that TNTM has high heat-resistant ability.1
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93.
主要讨论了A-B效应所产生的动力学机制,指出运动电子所产生的磁场和外磁场的相互叠加是产生A-B效应的动力学原因。如果能够屏蔽掉运动电子所产生的磁场使之不能和外磁场相互叠加,那么A-B效应也将随之消失。为了验证这一结论,提出了一种新的实验方案,该方案可以对A-B效应的动力学机制做出明确的判断。
关键词:
A-B效应
超导电性
迈斯纳效应
介观物理 相似文献
94.
95.
The cobalt(II) complex with (quinolin-8-yloxy)acetate, [CoCl(C11H8NO3)]n (1), has been prepared via the solvothermal method and characterized by IR, elemental analysis, UV- Vis diffuse-reflection spectra and single-crystal X-ray diffraction analysis. Complex 1 is a novel carboxylate-bridged one-dimensional helical cobalt(II) polymer, and the Co(II) centre exhibits an approximately square pyramidal CoClNO3 coordination geometry. It crystallizes in monoclinic, space group P21/n, with a = 9.1594(10), b = 6.8864(7), c = 17.290(2) , β = 102.629(3)o, C11H8ClCoNO3, Mr = 296.56, V = 1064.2(2) 3, Z = 4, Dc = 1.851 g/cm3, F(000) = 596, μ = 1.856 mm-1, the final R = 0.0308 and wR = 0.0807. Interestingly, the chain complexes are assembled to form two-dimensional networks through intermolecular face-to-face π-π stacking interactions with the centroid-to-centroid distance of 3.559(1) and the dihedral angle of 8.4(1)° between the aromatic rings. 相似文献
96.
97.
The electron paramagnetic resonance parameters D, g ∥ and g ⊥ for V3+ ions in α-Al2O3 crystals are calculated on the basis of the complete diagonalization method and the superposition model. In the calculation, the contributions of the variation of the cation–ligand bond lengths and bond angles are taken into consideration. The calculated results agree well with the experimental data. Our investigation shows that the local structure around the V3+ ions possesses a compressed trigonal distortion above the O2?-triangle and an elongated trigonal distortion in the lower one. 相似文献
98.
光波导横向耦合模理论包含正交耦合模理论和非正交耦合模理论两大类, 为了追求形式上的完美, 两类理论没有统一的解析解, 并且都没有对非匹配耦合系统中耦合功率的非对称性进行深入研究. 本文一方面由Helmholtz方程出发推导出了一种新型的非正交耦合模方程, 并对两类理论中的耦合模方程进行了统一处理和求解, 得到了一种统一的解析解; 另一方面根据所得到的统一的解析解对非匹配耦合系统中耦合功率的非对称性进行了详细研究, 计算结果表明非匹配耦合系统中的最大互耦合功率和最小自耦合功率均可用统一的解析解进行近似计算.
关键词:
光波导
耦合模理论
耦合器
最大耦合功率 相似文献
99.
100.
采用自由配体法将(1S,2S)-DPEN(1,2-diphenyl-1,2-ethylene-diamine)-Ru(TPP)2(TPP=三苯基膦,triphenylphosphine)配合物封装于NaY沸石分子筛超笼中,制备了(1S,2S)-DPEN-Ru(TPP)2/Y主客体材料(1S,2S)-DPEN=1,2-二苯基-1,2-乙二胺).采用等离子体发射光谱ICP、粉末X射线衍射(XRD)、紫外光谱(UV-Vis)、氮吸附等物理化学手段对所制备材料进行了表征.结果表明,(1S,2S)-DPEN-Ru(TPP)2配合物封装于Y型分子筛超笼中保持了原有的物理化学性能;作为苯乙酮不对称加氢催化剂,在优化条件下,苯乙酮的转化率可达100%,(R)-苯乙醇的对映体过量值(ee值)可达61.0%.该催化剂具有良好的稳定性和重复使用性. 相似文献