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71.
Yuge R Yudasaka M Miyawaki J Kubo Y Ichihashi T Imai H Nakamura E Isobe H Yorimitsu H Iijima S 《The journal of physical chemistry. B》2005,109(38):17861-17867
We succeeded in large-scale preparation of single-wall carbon nanohorns (SWNH) encapsulating C60 molecules in a liquid phase at room temperature using a "nano-precipitation" method, that is, complete evaporation of the toluene from a C60-SWNH-toluene mixture. The C60 molecules were found to occupy 6-36% of the hollow space inside the SWNH, depending on the initial quantity of C60. We showed that the C60 in C60@SWNHox was quickly released in toluene, and the release rate decreased by adding ethanol to toluene. Numerical analysis of the release profiles indicated that there were fast and slow release processes. We consider that the incorporation quantity and the release rate of C60 were controllable in/from SWNHs because SWNHs have large diameters, 2-5 nm. 相似文献
72.
Bagasse, corn husk, and switchgrass were pretreated with ammonia water to enhance enzymatic hydrolysis. The sample (2 g) was
mixed with 1–6 mL ammonia water (25–28% ammonia) and autoclaved at 120°C for 20 min. After treatment, the product was vacuum-dried
to remove ammonia gas. The dried solid could be used immediately in the enzymatic hydrolysis without washing. The enzymatic
hydrolysis was effectively improved with more than 0.5 and 1 mL ammonia water/g for corn husk and bagasse, respectively. In
bagasse, glucose, xylose, and xylobiose were the main products. The adsorption of CMCase and xylanase was related to the initial
rate of enzymatic hydrolysis. In corn husks, arabinoxylan extracted by pretreatment was substantially unhydrolyzed because
of the high ratio of arabinose to xylose (0.6). The carbohydrate yields from cellulose and hemicellulose were 72.9% and 82.4%
in bagasse, and 86.2% and 91.9% in corn husk, respectively. The ammonia/water pretreatment also benefited from switchgrass
(Miscanthus sinensis and Solidago altissima L.) hydrolysis. 相似文献
73.
Thermal decomposition of dolomite into CaCO3 and MgO under CO2 was investigated by isothermal kinetic measurements, X-ray diffraction analysis, and electron diffraction. The decomposition was described as an interfacial reaction. Crystalline CaCO3 is formed in an extremely orientated state even if the temperature is higher than the decomposition temperature of calcite, at least at the earlier stage of the decomposition. The crystallites of MgO grow with time and temperature, while the grain size of CaCO3 remains constant during the isothermal decomposition. The CaCO3 crystallite size is minimal at about 750°C. The classical theories of the mechanism of the formation of CaCO3 from dolomite were reexamined, and a direct formation theory was suggested on the basis of the results of X-ray analysis. 相似文献
74.
Ueda M Miyabe H Teramachi M Miyata O Naito T 《The Journal of organic chemistry》2005,70(17):6653-6660
The intermolecular radical addition to chiral nitrones 2, 4, 5, and 16 was studied. The isopropyl radical addition to Oppolzer's camphorsultam derivative 2 of glyoxylic nitrone proceeded with excellent diastereoselectivity to give the desired isopropylated product 3a accompanied by the diisopropylated product 3b. A high degree of stereocontrol in the reaction of cyclic nitrone 4 was achieved. The ethyl radical addition to nitrone 4 with triethylborane afforded the desired ethylated product 9a accompanied by the diethylated product 10a and the ethylated nitrone 11a. To evaluate the utility of cyclic nitrone 4, several alkyl radicals were employed in the addition reaction, which afforded the alkylated products 9b-d with excellent diastereoselectivities. In the presence of Mg(ClO(4))(2), the ethyl radical addition to BIGN 16 afforded selectively syn isomers. In contrast, the alkyl radical addition to 16 took place even in the absence of Lewis acid to give anti isomers. 相似文献
75.
76.
Issei Kasahara Masami Kanai Masako Taniguchi Ayako Kakeba Noriko Hata Shigeru Taguchi Katsumi Goto 《Analytica chimica acta》1989
The singly charged complex anion bis[2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulphopropylamino)phenolato]cobaltate(III) is intensely purple-violet and is stable over the pH range 1–13. Its absorption spectrum remains the same over this pH range. At pH2, it forms extractable ion pairs with long-chain quaternary ammonium ions and protonated alkylamines. Only the quaternary ammonium ions are extracted into chloroform at pH 11, hence separate extractions allow both types to be determined. The absorbance of the organic phase is measured at 594 nm. The apparent molar absorptivity is 7.0 × 104 l mol?1 cm?1. Calibration graphs for zephiramine, benzethonium and hexadecylpyridinium ions are linear over the range 0.1–2 × 10?6 M. The only interference found was from anionic surfactants. The method is applied to hair and fabric conditioners. 相似文献
77.
Abstract— We have found that clay acts as a novel model matrix for the amphiphilic protein-opsin to mimic the visible absorption spectrum of a protonated retinal Schiff base (RSB) in vivo. Without strong acids at ambient temperature, a visible broad absorption spectrum with a LDmax at 530 nm covering the range from 400 to 680 nm was achieved for the protonated RSB with cationic surfactant-modified montmorillonite clay. The interlayers of the dimethyloctadecylamine (DOA) modified clay were found to provide amphiphilic space allowing the amphiphilic RSB to be intercalated easily and sequentially and protonated by the DOA. It is proposed that the visible absorption spectrum at LD, 530 nm was attributable to electrostatic effects, permitting the appropriate distance between the nitrogen of the protonated RSB and the negatively charged clay interlayers and also to the anisotropic orientation of the RSB molecules in the interlayers. 相似文献
78.
NMR measurements coupled with pattern-recognition analysis offer a powerful mixture-analysis tool for latent-feature extraction and sample classification. As fundamental applications of this analysis for mixtures, the 1H spectra of 176 kinds of green, black, oolong and other tea infusions were acquired by a 500 MHz NMR spectrometer. Each spectrum pattern was analyzed by a multivariate statistical pattern-recognition method where Principal Component Analysis (PCA) was used in combination with Soft Independent Modeling of Class Analogy (SIMCA). SIMCA effectively selected variables that contribute to tea categorization. The final PCA resulted in clear classification reflecting the fermentation and processing of each tea, and revealed marker variables that include catechin and theanine peaks. 相似文献
79.
Takahiro Hirotsu Shunsaku Katoh Kazuhiko Sugasaka Masako Sakuragi Kunihiro Ichimura Yoshio Suda Mitsugi Fujishima Yoshimoto Abe Takahisa Misonoo 《Journal of polymer science. Part A, Polymer chemistry》1986,24(8):1953-1966
Preparation of new chelating polymers bearing dihydroxamic acid groups and the adsorptive ability for uranium in sea water are described. Chloromethylated polystyrene crosslinked with divinylbenzene was treated with diethyl malonate in N, N-dimethylformamide to give the polymer having diethyl malonate groups. This polymer was then treated with hydroxylamine in methanol to afford the dihydroxamic acid polymer. The presence of hydroxamic acid groups was confirmed by the appearance of IR absorption band at 1680 cm?1. The dihydroxamic acid polymer contained carboxylic acid groups as well as hydroxamic acid ones, and the contents of carboxylic acid and hydroxamic acid groups were estimated from elemental analysis to be 2–3 and 2–4 mmol/g, respectively. The polymer showed the adsorptive ability of 40 μg-U/g in 8 days for uranium in sea water. In addition, the polymer showed the selective adsorptivity for iron, nickel, copper, and zinc as well as uranium. The macroreticular-type polymer showed much higher adsorption rate for uranium in sea water than the gel-type ones did, suggesting that the rate depends on the diffusion of the uranium in the polymer support. 相似文献