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71.
The polymerization of isobutyl vinyl ether was studied in a heterogeneous system using iron (II) sulfate calcined in air at various temperatures as a catalyst. The maximum activity was shown by the catalyst calcined at 700°C, which effected the polymerization at room temperature in a few seconds, while the sulfate treated at 750°C was totally inactive. Poly(vinyl ethyl ether) was also obtained by the FeSO4 (700°C) catalyst at room temperature. This catalyst formed the crystalline polymer (melting temperature 135–138°C) when the reaction was performed in toluene as solvent at room temperature. Poisoning experiments with Hammett indicators were carried out with the FeSO4 (700°C) catalyst. The treatment with n-butylamine rendered it inactive in the reaction of isobutyl vinyl ether, while its catalytic activity was little affected by dicinnamalacetone. On the basis of the observed results, the nature of active sites of catalyst is discussed. 相似文献
72.
Makoto Minato Takefumi Kaneko Shogo Masauji Takashi Ito 《Journal of organometallic chemistry》2006,691(11):2483-2488
We describe the synthesis of a new asymmetric P,N,N′-tridentate ligand (bis(pyrid-2-ylethyl) menthylphosphine, BPEMP), containing two pyridyl rings and (1S,2R,5S)-menthylphosphino group. The ligand is obtained in five steps from natural abundant l-menthol. The coordination behavior of the ligand toward cationic (allylic)Pd(II) moiety and its first application in palladium-catalyzed asymmetric allylic alkylation are presented. Crystallographic and spectroscopic analyses reveal that [(η3-allylic)Pd(BPEMP)]+ complex forms only one isomer in the solid state as well as in solution. 相似文献
73.
A highly convergent total synthesis of gymnocin-A, a cyctotoxic polyether marine natural product, has been achieved. The synthesis features Suzuki-Miyaura coupling of the ABCD and FGHIJKLMN rings, stereoselective introduction of the C17 hydroxyl group, ring-closure of the F ring, and a late-stage incorporation of a 2-methyl-2-butenal side chain. 相似文献
74.
Post-biotinylation of the alkyl azide derivative of trifluoromethyl phenyldiazirine (TPD) was elucidated to apply a photoaffinity biotinylation technique. A photo-modified polyvinilidene difluoride (PVDF) membrane was used as a photolabeled component and we introduced biotin by Staudinger-Bertozzi ligation. The 15 pmol amount of biotinylated reagent was still effective for the visualization of cross-linked product on the matrix. The results show the potential utility of alkyl azide carrying TPD derivatives in the application of photoaffinity biotinylation, which could be useful for the ligands with tight structural requirements. 相似文献
75.
Takeo Miyazawa Takeshi Endo Makoto Okawara 《Journal of polymer science. Part A, Polymer chemistry》1985,23(5):1527-1535
Some hindered amine polymers containing 2,2,6,6-tetramethylpiperidine structure were synthesized. A new monomer, 4-O-vinylbenzyl-2,2,6,6-tetramethylpiperidine, was homopolymerized and copolymerized with some vinyl monomers in the presence of AIBN as an initiator. The obtained amine polymers were oxidized with hydrogen peroxide to obtain the polymers having nitroxyl radical moiety. 相似文献
76.
Homogeneous solutions are formed from equimolar amounts of Ce(NH4)2(NO3)6 and EDTA. These solutions hydrolyze single-stranded DNA far more efficiently than double-stranded DNA. In contrast, Ce(IV) hydroxide gel, obtained in the absence of EDTA, hydrolyzes both single-stranded and double-stranded DNAs at almost the same rates. In order to achieve this substrate-specificity sufficiently, the mole ratio of EDTA to Ce(NH4)2(NO3)6 must be 1.0 or greater. By using this remarkable specificity of Ce(IV)/EDTA complex, gap-site in substrate DNA is selectively hydrolyzed. The scission-site is modulated by use of appropriate combination of oligonucleotide additives. The reactions have been kinetically analyzed. 相似文献
77.
De-Qi Yuan Yuewei Zhao Makoto Fukudome Kahee Fujita 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):125-129
One or two coumarin units were incorporated to the primary face of γ-cyclodextrin (γ-CD), and the resultant coumarin derivatives
were employed to harvest the chemical energy generated in the reaction of bis(trichlorophenyl)oxalate with hydrogen peroxide.
In comparison with the coumarin without CD cavity for molecular recognition, the coumarin–CD conjugates demonstrated much
higher chemiluminescence inetensity, indicating that the CD moiety remarkably improves the chemical energy transfer. 相似文献
78.
Yoshizawa M Ono K Kumazawa K Kato T Fujita M 《Journal of the American Chemical Society》2005,127(31):10800-10801
Two molecules of planar MII(acac)2 complexes (M = Pt, Pd, and, Cu; acac = acetylacetonato) are efficiently stacked within an organic-pillared coordination cage, exhibiting characteristic spectroscopies (for M = Pt and Pd) and electron spin-spin coupling (for M = Cu) attributable to metal-metal interaction. 相似文献
79.
A series of parallel reactions were carried out for the tandem Ugi/Diels-Alder reaction on our MPEG-O-CH2- platform. Ninety-six out of a 100 entries were successful to give complex heterotricycles. The stereoselectivity was found not to be influenced by the building blocks used for amine and carboxylic acid components. An unexpected side pathway was found but was suppressed by employing appropriate reaction conditions. The reaction was also performed on solid phase, by which a larger library is potentially realized by employing the split-pool method. 相似文献
80.