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101.
102.
Matsui J Mitsuishi M Aoki A Miyashita T 《Journal of the American Chemical Society》2004,126(12):3708-3709
We describe here a polymer nanosheet assembly that serves as a molecular photoswitching and optical exclusive OR (EXOR) logic gate. Separate polymer nanosheets (monolayers) containing phenanthrene, anthracene, and dinitrobenzene chromophore were prepared by the Langmuir-Blodgett technique (LB films). A bilayer-couple, consisting of phenanthrene (sensitizer) monolayer and dinitrobenzene (acceptor) monolayer, and the other couple, of anthracene monolayer and dinitrobenzene monolayer, were confirmed to function as a photodiode showing current rectification on light irradiation. The two photodiodes are connected as each photocurrent direction becomes opposite. In the polymer photodiode array (LB films), anodic photocurrent was observed when the anthracene was selectively excited. On the other hand, cathodic photocurrent was observed by selective excitation of the phenanthrene. Moreover, the output photocurrent displayed a very small value when the phenanthrene and anthracene were excited simultaneously. The performance is discussed for this gate's application to an optical EXOR logic gate. 相似文献
103.
104.
As a chemiluminescent chemosensor that emits yellow light on reacting with a superoxide radical anion (O2−) and has a lipophilic character, a 6-phenylimidazo[1,2-a]pyrazin-3(7H)-one derivative possessing a boradiazaindacene (BODIPY) at the para position of 6-phenyl (1) was synthesized. The lipophilicity of 1 was investigated by reversed-phase liquid chromatography, and its log Pow value was found to be 3.57. This value was much higher than that of 2-methyl-6-(4-methoxypheyl)imidazo[1,2-a]pyrazin-3(7H)-one (MCLA, log Pow=1.19) and 6-[4-[2-{N′-(5-fluoresceinyl)thioureido}ethoxy]phenyl]-2-methylimidazo[1,2-a]pyrazin-3(7H)-one (FCLA, log Pow=−0.08), and it was comparable to that of benzenoid hydrocarbons. The O2−-induced chemiluminescence of 1 was investigated using the hypoxanthine/xanthine oxidase system as the source of O2−, and as a result, yellow emission was observed. The maximum wavelength was observed at 542 nm, and it was longer than that of FCLA. 相似文献
105.
106.
Saphwan Al-Assaf Makoto Sakata Catherine McKenna Hiromitsu Aoki Glyn O. Phillips 《Structural chemistry》2009,20(2):325-336
The tendency of polysaccharides to associate in aqueous solution has long been recognised. Molecular associations can profoundly
affect their performance in a given application due to its influence on the molecular weight, shape and size. This will ultimately
determine how the molecules will interact with each other, with other molecules and with water. There are several factors,
such as hydrogen bonding, hydrophobic association, ion mediated association, electrostatic interaction, concentration dependence
and the presence of proteinaceous components, which affect this behaviour. Our objective is to highlight the role of the proteinaceous
component, present in acacia gum, to promote associations when the gum is subjected to various processing treatments such
as maturation, spray drying and irradiation. The results demonstrate the ability of the proteinaceous component to promote
hydrophobic associations which influence the size and proportion of the arabinogalactan high molecular weight component (AGP).
Heat treatment in solid state (maturation) increases the hydrophobic character of the gum and hence its emulsification performance.
Spray drying also involves aggregation through hydrophobic association but changes the surface properties of peptide moieties
to become more hydrophilic compared to the association promoted by the maturation treatment in the solid state. Irradiation
induced cross-linking, in the presence of unsaturated gas, was used to introduce C–C bonds into the carbohydrate moiety and
thus confirms the hydrophobic association prompted by the heat used in the maturation and spray drying. This association can
be reversed by treatments, such as filtration or high pressure homogenisation. The results reported here reconcile the contradiction
about structure of gum arabic proposed by the wattle-blossom and twisted hairy rope models and shows that the AGP fraction
is basically an aggregated fraction made up of AG units stabilized by low molecular weight highly proteinaceous components.
相似文献
Saphwan Al-AssafEmail: |
107.
108.
Tsuda M Izui N Shimbo K Sato M Fukushi E Kawabata J Katsumata K Horiguchi T Kobayashi J 《The Journal of organic chemistry》2003,68(13):5339-5345
A novel cytotoxic 16-membered macrodiolide, amphidinolide X (1), has been isolated from a marine dinoflagellate Amphidinium sp. (strain Y-42). The gross structure of 1 was elucidated on the basis of spectroscopic data including one-bond and long-range (13)C-(13)C correlations. The relative and absolute stereochemistries were determined by combined analyses of NOESY data and (1)H-(1)H and (1)H-(13)C coupling constants of 1 and NMR data of the degradation products. Amphidinolide X (1) is the first macrodiolide consisting of polyketide-derived diacid and diol units from natural sources. The biosynthetic origins of 1 were investigated by means of feeding experiments with (13)C-labeled acetates. 相似文献
109.
Eri Sano Weihua Li Hitomi Yuki Xinli Liu Tomomi Furihata Kaoru Kobayashi Kan Chiba Saburo Neya Tyuji Hoshino 《Journal of computational chemistry》2010,31(15):2746-2758
Cytochrome P450 (CYP) is deeply involved in the metabolism of chemicals including pharmaceuticals. Therefore, polymorphisms of this enzyme have been widely studied to avoid unfavorable side effects of drugs in chemotherapy. In this work, we performed computational analysis of the mechanism of the decrease in enzymatic activity for three typical polymorphisms in CYP 2C9 species: *2, *3, and *5. Based on the equilibrated structure obtained by molecular dynamics simulation, the volume of the binding pocket and the fluctuation of amino residues responsible for substrate holding were compared between the wild type and the three variants. Further docking simulation was carried out to evaluate the appropriateness of the binding pocket to accommodate substrate chemicals. Every polymorphic variant was suggested to be inferior to the wild type in enzymatic ability from the structural viewpoint. F‐G helices were obviously displaced outward in CYP2C9*2. Expansion of the binding pocket, especially the space near F′ helix, was remarkable in CYP2C9*3. Disappearance of the hydrogen bond between K helix and β4 loop was observed in CYP2C9*5. The reduction of catalytic activity of those variants can be explained from the deformation of the binding pocket and the consequent change in binding mode of substrate chemicals. The computational approach is effective for predicting the enzymatic activity of polymorphic variants of CYP. This prediction will be helpful for advanced drug design because calculations forecast unexpected change in drug efficacy for individuals. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
110.
Takuji Hirose Kumiko Naito Megumi Nakahara Hiroaki Shitara Yoshio Aoki Hiroyuki Nohira Bruce W. Baldwin 《Journal of inclusion phenomena and macrocyclic chemistry》2002,43(1-2):87-93
Two Kemp's acid diamides were synthesized and applied to chiral amine recognition using 1H NMR analysis. One derivative based on 1-(1-naphthyl)ethylamine had good chiral recognition of six amines and was useful to determine the optical purity for three amines, i.e., methylbenzylamine, 1-(1-naphthyl)ethylamine and 1- henylpropylamine,however, the cyclohexylethylamine derivative showed little discrimination for the amines studied. Together with the results for alkylamines, it was shown that aromatic structure was important for aromatic shielding anisotropy and –– interactions between host and guest. The structure of the 1-(1-naphthyl)ethylamine derivative in solution was also considered based on 1H NMR data and computer simulation. 相似文献