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61.
Dr. Baoyan Xing Dr. Sai Ge Prof. Jianguo Zhao Dr. Hui Yang Dr. Jie Song Dr. Yu Geng Dr. Yuying Qiao Prof. Ling Gu Prof. Peide Han Prof. Guibin Ma 《ChemistryOpen》2020,9(10):1018-1026
Solid-state NMR analysis on wurtzite alloyed CdSe1−xSx crystalline nanoparticles and nanobelts provides evidence that the 113Cd NMR chemical shift is not affected by the varying sizes of nanoparticles, but is sensitive to the S/Se anion molar ratios. A linear correlation is observed between 113Cd NMR chemical shifts and the sulfur component for the alloyed CdSe1−xSx (0<x<1) system both in nanoparticles and nanobelts (δCd=169.71⋅XS+529.21). Based on this correlation, a rapid and applied approach has been developed to determine the composition of the alloyed nanoscalar materials utilizing 113Cd NMR spectroscopy. The observed results from this system confirm that one can use 113Cd NMR spectroscopy not only to determine the composition but also the phase separation of nanomaterial semiconductors without destruction of the sample structures. In addition, some observed correlations are discussed in detail. 相似文献
62.
Márton Zwillinger Dr. Post Sai Reddy Dr. Barbara Wicher Dr. Pradeep K. Mandal Dr. Márton Csékei Dr. Lucile Fischer Dr. András Kotschy Prof. Dr. Ivan Huc 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(72):17366-17370
Helically folded aromatic oligoamide foldamers have a size and geometrical parameters very distinct from those of α-helices and are not obvious candidates for α-helix mimicry. Nevertheless, they offer multiple sites for attaching side chains. It was found that some arrays of side chains at the surface of an aromatic helix make it possible to mimic extended α-helical surfaces. Synthetic methods were developed to produce quinoline monomers suitably functionalized for solid phase synthesis. A dodecamer was prepared. Its crystal structure validated the initial design and showed helix bundling involving the α-helix-like interface. These results open up new uses of aromatic helices to recognize protein surfaces and to program helix bundling in water. 相似文献
63.
64.
人血清白蛋白多种结合位点的存在使其成为许多药物可能的结合靶点. 土贝母皂苷具有广泛的生理和药理活性, 它与蛋白质相互作用机制的研究对于深入了解其药理药效具有重要的意义. 采用荧光光谱法研究了土贝母皂苷II (TBMSⅡ)与人血清白蛋白(HSA)之间的相互作用, 根据Stern-Volmer荧光淬灭方程计算得293, 298, 303, 308 K时TBMSⅡ与HSA相互作用的结合常数分别为1.002×105, 0.701×105, 0.514×105, 0.411×105 L•mol-1. 由实验计算出热力学参数焓变ΔH为-44.829 kJ•mol-1, 熵变ΔS为-57.497 J•mol-1•K-1, 表明分子间的氢键及疏水作用是TBMSⅡ-HSA复合物的主要作用力, 结合位点位于HSA的亚结构ⅡA, 这与分子模拟方法的结果相一致. 依据能量转移原理求得TBMSⅡ与HSA间的距离为4.95 nm|三维、同步荧光光谱及圆二色谱的结果表明TBMSⅡ的加入使HSA构象发生变化, α-螺旋结构有所下降. 相似文献
65.
Rahul B. Kawthekar Sai Kumar Chakka Vivian Francis Pher G. Andersson Hendrik G. Kruger Glenn E.M. Maguire Thavendran Govender 《Tetrahedron: Asymmetry》2010,21(7):846-852
A novel family of eleven new tetrahydroisoquinoline (TIQ)–oxazoline intermediates and five corresponding copper(II) catalysts has been developed and applied to the catalytic asymmetric Henry reaction of various aldehydes with nitromethane to provide β-hydroxy nitroalkanes in high conversion (>99%). This paper describes the synthesis of the TIQ compounds from l-dihydroxyphenylalanine (l-DOPA) as the starting material. The chiral ligands were complexed in situ with various transition metals such as Cu, Sc, Co, Zn, Ni and Mn and tested as a chiral catalyst for the Henry reaction. The reaction was optimized in terms of the metal, counter ion, solvent, temperature and over a range of substrates. The corresponding catalyst with copper(II) acetate and 2-propanol as the solvent provides the best enantioselectivities (up to 77% ee) of the corresponding nitroalcohol for 4-chlorobenzaldehyde. 相似文献
66.
Byron K. Peters Sai Kumar Chakka Tricia Naicker Glenn E.M. Maguire Hendrik G. Kruger Pher G. Andersson Thavendran Govender 《Tetrahedron: Asymmetry》2010,21(6):679-687
The use of the tetrahydroisoquinoline scaffold is well documented in biologically active compounds. However, reports of the utilisation of tetrahydroisoquinoline compounds in asymmetric catalysis are limited. The synthesis of novel diamine ligands possessing the tetrahydroisoquinoline (tetrahydroisoquinoline) backbone and evaluation of their activity in the asymmetric transfer hydrogenation of acetophenone are presented. The diamine ligands in conjunction with i-PrOH as the hydrogen source and [RhCl2(Cp1)]2 as the metal precursor proved to be the most effective of the tetrahydroisoquinoline derivatives for this catalytic system. Water was found to have a profound influence on the enantioselectivity of the reaction. Optimisation of the amount water, i-PrOH and catalytic loading content rendered the best result of 70% enantioselectivity for the (S)-1-phenylethanol isomer product. 相似文献
67.
The effects of power ultrasound on four metal-nonmetal powdered systems: copper-sulphur iron-sulphur, zinc-sulphur and magnesium-sulphur in various solvents, such as hexane and carbon disulphide, are briefly examined here. For each system, a sonication time of 30 min was affected. The sonicated products are analysed by X-ray diffraction, X-ray fluorescence and atomic absorption spectrophotometry to determine their qualitative and quantitative compositions and the percentage yields of the products obtained are then compared and discussed. 相似文献
68.
研究了在pH 6 2 5~ 7 5 5KH2 PO4 Na2 HPO4 缓冲介质中 ,铜与邻菲咯啉形成配合物而使荧光熄灭的实验条件 ,建立了荧光熄灭法测定微量铜的新方法。该方法的λex =2 6 6nm ,λem =36 8nm ,铜含量在 8~ 30 0ng·mL- 1 范围内 ,有良好的线性关系 ,相关系数r=0 9996 ,检出下限为 10 4ng·mL- 1 。用本法经巯基棉分离测定了环境水样中的微量铜。 相似文献
69.
Li ZQ Podzorov V Sai N Martin MC Gershenson ME Di Ventra M Basov DN 《Physical review letters》2007,99(1):016403
We report on an infrared spectroscopy study of mobile holes in the accumulation layer of organic field-effect transistors based on rubrene single crystals. Our data indicate that both transport and infrared properties of these transistors at room temperature are governed by light quasiparticles in molecular orbital bands with the effective masses m* comparable to free electron mass. Furthermore, the m* values inferred from our experiments are in agreement with those determined from band structure calculations. These findings reveal no evidence for prominent polaronic effects, which is at variance with the common beliefs of polaron formation in molecular solids. 相似文献
70.
Catalytic Asymmetric Inverse‐Electron‐Demand Oxa‐Diels–Alder Reaction of In Situ Generated ortho‐Quinone Methides with 3‐Methyl‐2‐Vinylindoles 下载免费PDF全文
Jia‐Jia Zhao Si‐Bing Sun Sai‐Huan He Dr. Qiong Wu Prof. Dr. Feng Shi 《Angewandte Chemie (International ed. in English)》2015,54(18):5460-5464
The first catalytic asymmetric inverse‐electron‐demand (IED) oxa‐Diels–Alder reaction of ortho‐quinone methides, generated in situ from ortho‐hydroxybenzyl alcohols, has been established. By selecting 3‐methyl‐2‐vinylindoles as a class of competent dienophiles, this approach provides an efficient strategy to construct an enantioenriched chroman framework with three adjacent stereogenic centers in high yields and excellent stereoselectivities (up to 99 % yield, >95:5 d.r., 99.5:0.5 e.r.). The utilization of ortho‐hydroxybenzyl alcohols as precursors of dienes and 3‐methyl‐2‐vinylindoles as dienophiles, as well as the hydrogen‐bonding activation mode of the substrates met the challenges of a catalytic asymmetric IED oxa‐Diels–Alder reaction. 相似文献