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91.
Sakata M Nakayama M Kamada T Kunitake M Mizokami H Hirayama C 《Journal of chromatography. A》2004,1030(1-2):117-122
To remove nucleic acids from cellular products as drugs, cross-linked N,N-dimethylaminopropylacrylamide (DMP) particles with cationic functional groups were prepared. The particle's hydrophobicity and its anion-exchange capacity were easily adjusted by changing the cross-linking agent and the DMP ratio in the cross-linking, respectively. When divinylbenzene (DVB) was used as a cross-linking agent and the DMP ratio (in the cross-linking) was adjusted to 90 mol%, the particles (DMP-DVB, 90:10) showed the highest adsorbing activity of DNA (salmon spermary). Its adsorption capacity was 54 mg/ml adsorbent. On the other hand, the adsorption of bovine serum albumin (BSA) to the DMP-DVB extremely increased with increase in the adsorbent's pore size (molecular mass exclusions; M(lim)) from 2 x 10(3) to 1 x 10(4), but decreased with increase in the buffer's ionic strength (mu) to 0.2 or stronger. As a result, when the DMP-DVB (80:20) with M(lim) 2 x 10(3) was used as adsorbent by a column method at pH, 7.2 and mu = 0.17, it only selectively removed DNA from a BSA solution, including 1000 microg/ml of BSA and 10 microg/ml of DNA. The adsorbent decreased the concentration of DNA in the BSA solution to < 10 ng/ml, and the recovery rate of BSA was more 98%. 相似文献
92.
Hirayama Y Nakamura T Uehara S Sakamoto Y Yamaguchi K Sei Y Iwamura M 《Organic letters》2005,7(4):525-528
New aliphatic polyester-type dendrimers were synthesized using a new AB2-type building block 3, prepared from benzyl acetoacetate and 2 equiv of tert-butyl acrylate by acetoacetic acid ester synthesis. The reiterative [deprotection by HCO2H, then EDCI/DMAP coupling] sequence using divergent growth method gave [G1]-4tBu-[G5]-64tBu dendrimers. 13C NMR relaxation time (T1) measurements on the carboxy carbons show that the extended chain conformations are predominant in CDCl3. [structure: see text] 相似文献
93.
Lacie C. Hirayama 《Tetrahedron letters》2005,46(13):2315-2318
We report a general method for the indium-mediated Barbier-type enantioselective allylation of both aromatic and aliphatic aldehydes using commercially available (1S,2R)-(+)-2-amino-1,2-diphenylethanol as a chiral auxiliary. Using only two equivalents of allyl bromide, excellent yields and very good to excellent enantioselectivities are obtained. To our knowledge, the enantioselectivities reported herein are the highest obtained for indium-promoted allylations of carbonyl compounds. 相似文献
94.
Procedures are described for the determination of arsenite, arsenate and monomethylarsonic acid in aqueous samples. The arsenicals (after reduction of arsenic to the tervalent state) readily react with 2,3-dimercaptopropanol (BAL) to yield their BAL complexes. The products are extracted with benzene and introduced into a gas Chromatograph equipped with a flame-photometric detector for sulphur. One aliquot of sample is treated with stannous chloride solution and potassium iodide solution to reduce arsenate and monomethylarsonic acid, then BAL is added and the complexes are extracted with benzene. The extract is analysed for total inorganic As plus monomethylarsonic acid. Magnesia mixture and phosphate solution are added to another aliquot to remove arsenate by co-precipitation with magnesium ammonium phosphate. The precipitate is filtered off and arsenite determined in the filtrate. The detection limits are 0.02 ng of As for arsenate and arsenite and 0.04 ng of As for monomethylarsonic acid. 相似文献
95.
The π→π* absorption bands of azulene show circular dichroism in the presence of (+)-nopinone. 相似文献
96.
Ryoichi Hirayama Masahiro Kawase Tetsutaro Kimachi Kiyoshi Tanaka Fumio Yoneda 《Journal of heterocyclic chemistry》1989,26(5):1255-1259
Various 8-hydroxy-5-deazaflavin derivatives were synthesized as the model compounds of coenzyme F420-These compounds oxidized benzylamine to benzaldehyde more efficiently than the corresponding 8-unsubstituted 5-deazaflavins. 相似文献
97.
98.
T. Machida S. Ishizuka K. Muraki Y. Hirayama S. Komiyama 《Physica E: Low-dimensional Systems and Nanostructures》2000,6(1-4)
We have studied the resistance fluctuations (RF) in integer quantum-Hall transitions for high-mobility two-dimensional electron gas systems. The role of coherence in RF is examined by investigating the conductance through two scattering regions, that are spatially separated but interfere quantum-mechanically with each other. The phase coherence does not play a substantial role in determining the pattern of RF, whereas it affects the amplitude of RF. 相似文献
99.
Kazuki Sada Kazunori Nakano Kiyoshi Hirayama Mikiji Miyata Satoshi Sasaki Kiichi Takemoto 《Supramolecular chemistry》2013,25(1):35-44
Abstract Molecular recognitions of medium size lactones by enclathration of cholic acid (CA) are described. Size and location of the substituents on the lactone rings play an important role for enclathration. Lactones within the limited steric dimensions are included in CA, and larger or smaller ones are not included to give guest-free crystals of CA. Moreover, CA partially separates one enantiomer from racemic lactones by recystallization. X-ray crystallographic studies reveal that all included lactones form the β-trans type bilayer structure having a pentagonal void channel with a side pocket. The cross-sections illustrate that the lactone rings are incorporated in the center of the channel and that the substituents of the guests are fixed in the side pockets. The asymmetric channel enables CA to discriminate size and chirality of medium size lactones. 相似文献
100.
The interaction of atomic H with Ag(1 1 1)/Si(1 1 1)7 × 7 surfaces was studied by thermal desorption (TD) spectroscopy and scanning tunneling microscopy (STM) at room temperature. TD spectroscopy revealed an intense peak from mono H–Si bonds, even though the Si surface was covered by the Ag atoms. This peak was not observed from Ag-coated SiO2/Si substrates. STM observation showed no clear change of the Ag surface morphology resulting from H exposure. All these results indicate that the atomic H adsorbs at neither the Ag surfaces nor Ag bulk sites, but at the Ag/Si interface by diffusing through the Ag film. 相似文献