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1.
Gábor Blaskó S.Fazal Hussain Alan J. Freyer Maurice Shamma 《Tetrahedron letters》1981,22(33):3127-3130
The dark yellow indenobenzazepine alkaloids lahorine () and lahoramine () have been found in Lam. (Fumariaceae). In a transformation with biogenetic implications, treatment of the spirobenzylisoquinolines dihydrofumariline () and dihydroparfumidine () with methanesulfonyl chloride and triethylamine in dry THF, followed by iodine oxidation, provided and , respectively. 相似文献
2.
Dihydroprotoberberine salts 5, 10, and 14, rearrange in base to the spirobenzylisoquinolines 8, 12, and 16, respectively. But the dihydroprotoberberine salt 18, which does not possess a phenolic function in ring D, rearranges to the dibenzocyclopent[b]azepine 21 through the intermediacy of the aziridinium ion 20. 相似文献
3.
S. G. Yunusova S. D. Gusakova A. I. Glushenkova U. K. Nadzhimov Sh. Turabekov SA. Musaev 《Chemistry of Natural Compounds》1991,27(2):147-150
A comparative analysis has been made of the amounts of lipids and their fatty-acid compositions in the seeds of the lines of agenetic collection of cotton plants of the speciesGossypium hirsutum and their hybrids and the variety Tashkent-1. The results obtained on the fatty-acid compositions of some hybrids make it possible to recommend the use of individual lines of cotton plants as donors for improving the food-value indices of cottonseed oil.Institute of Chemsitry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 173–176, March–April, 1991. 相似文献
4.
Berberine chloride (1) upon treatment with NaOAc-Ac2O yields naphthalene derivatives 4 and 5 In like fashion, 8 gives naphthalene 10; isoquinoline methiodide leads to β-naphthyl acetate; and 12 provides 14. The reaction has been extended to the 3-carbonyl pyridinium series where 3-acetylpyridine methiodide and 3-pyridinecarboxaldehyde methiodide furnish lactones 16 and 17, respectively. All these transformations proceed by initial nucleophilic attack of the acetic anhydride anion on the immonium carbon atom. 相似文献
5.
Speech processing in the auditory system. II: Lateral inhibition and the central processing of speech evoked activity in the auditory nerve 总被引:4,自引:0,他引:4
S A Shamma 《The Journal of the Acoustical Society of America》1985,78(5):1622-1632
A biologically realistic model of a uniform lateral inhibitory network (LIN) is shown capable of extracting from the complex spatio-temporal firing patterns of the cat's auditory nerve the formants and low-order harmonics of synthetic voiced speech stimuli. The model provides a realistic mechanism to utilize the temporal aspects of the firing and thus supports the hypothesis that the neural coding of complex sounds in terms of average rates can be supplemented by the information coded in the synchronous firing. At low levels of intensity the LIN can sharpen the average rate profiles. At moderate and high levels the LIN uses the cues available in the distribution of phases of the synchronous activity which exhibit rapid relative phase shifts at specific characteristic frequency (CF) locations (corresponding to the frequencies of the low-order harmonics in the stimulus). These temporal phase shifts manifest themselves at the input of the LIN as steep and localized spatial discontinuities in the instantaneous pattern of activity across the fiber array. The LIN enhances its output from these spatially steep input regions while suppressing its output from spatially smooth input regions (where little phase shifts occur). In this manner the LIN recreates from the response patterns a representation of the stimulus spectrum using the temporal cues as spatial markers of the stimulus components rather than as absolute measures of their frequencies. Similar results are obtained with various lateral inhibitory topologies, e.g., recurrent versus nonrecurrent, single versus double layer, and linear versus nonlinear. 相似文献
6.
The Dirichlet problem for the region of the plane inside closed smooth curve C for second-order elliptic equations is considered. It is shown that under certain circumstances the solution u can be written uniquely in the form u(P) = ∝cF(P, Q) g(Q) dsQ, where F(P, Q) is the fundamental solution of the elliptic equation, and g?L2 if the boundary value function f is absolutely continuous with square integrable derivative (f?W); and u(P) = p(F(P, ·)) where p is a unique bounded linear functional on W if f?L2. These representations are valid in the exterior of C also. As special cases with slight modifications, the exterior Dirichlet problems for the Helmholtz and Laplace equations are mentioned.It is shown also that if kernel F(P′, Q), with P′ and Q on C, has a complete set of eigenfunctions {ψk(P′)} then u(P) can be expanded in a series of their extensions {ψk(P)}, where ψk(P) = λk ∝cF(P, Q) ψk(Q) dsQ. 相似文献
7.
8.
(+)-Parviflorine (), found in Lam. (Fumariaceae), is the first known glycosidic spirobenzylisoquinoline alkaloid. Its acid hydrolysis yields (+)-parfumine () and D-glucose. Klyne's rule indicates that is a β-D-glucoside. The absolute configuration shown in expressions is predominant among spirobenzylisoquinolines. A generalization has been drawn between plant source and the oxygenation pattern of ring C for the spirobenzylisoquinoline alkaloids. 相似文献
9.
The complexes [Zn(phenylacetato)2(2-aminopyridin)2] (3), [Zn(phenylacetato)2(1,10-phenanthroline)]·H2O (4), and [Zn(phenylacetato)2(2,9-dimethyl-1,10-phenanthroline)]·0.5 H2O (5) were prepared and characterized by IR-, UV–Visible, 1H and 13C NMR spectroscopy, and single crystal X-ray diffraction. BNPP hydrolysis of the complexes and their parent nitrogen ligands showed that the hydrolysis rate of bis-(4-nitrophenyl) phosphate (BNPP) was 1.7 × 105 L mol?1 s?1 for 3, 3.1 × 105 L mol?1 s?1 for 4 and 4.3 × 104 L mol?1 s?1 for 5. Antibacterial activities show the effect of complexation on activity against Gram-positive (S. epidermidis, S. aureus, E. faecalis, M. luteus and B. subtilis) and Gram-negative (K. pneumonia, E. coli, P. mirabilis and P. aeruginosa) bacteria using the agar well diffusion method. Complex 4 showed good activity against G? bacteria except P. aeruginosa, and against G+ bacteria except E. ferabis. Complex 5 showed no activity against G? bacteria, low activity against M. luteus and B. subtilis bacteria and high activity against S. epidemidis and S. aureus. Complex 3 did not show any activity against G? or G+ bacteria. 相似文献
10.
利用溶液聚合和成酰胺反应合成了多功能梳状两亲性共聚物,聚(甲基丙烯酸-co-甲基丙烯酸十八酯)-(乙醇胺-乙二胺叶酸)(PSM-EE-FA).用红外光谱(FTIR),核磁共振(1H-NMR)及凝胶渗透色谱(GPC)表征了该聚合物的结构及分子量分布.实验结果证明合成了该聚合物,其数均分子量(Mn)为28600,多分散性为1.375.用该两亲梳状聚合物包覆油溶性CdSe/ZnS量子点,通过相转移作用,得到水溶性靶向量子点(PSM-EE-FA-QDs).该水溶性量子点溶液具有较好的稳定性.通过紫外-可见(UV-Vis)及荧光发射光谱分析对该量子点的光学性质进行研究.结果表明,PSM-EE-FA-QDs的紫外-可见光谱及荧光发射光谱峰形与原量子点基本一致.由于量子点表面聚合物层的形成,峰位发生少量红移.该量子点水溶液的荧光强度是原量子点氯仿溶液的98%,荧光产率是原量子点氯仿溶液的95%.动态光散射(DLS)及透射电镜(TEM)测试结果表明水溶性量子点分布均匀.合成的水溶性量子点不但光学性能稳定,而且聚合物及水溶性量子点的合成方法较为简便. 相似文献