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781.
Dr. Shuji Saito 《Colloid and polymer science》1968,226(1):10-14
Zusammenfassung Wasserunlösliche Copolymeren von Polyvinylalkohol-Azetat werden in wässerigen Lösungen nicht-ionischer Tenside optisch klar solubilisiert. Aus den Viskositätsmessungen ist zu schließen, daß sich die im Wasser eng gepackten Polymerenketten in den Tensidlösungen aufweiten. Die Trübungstemperatur der wässerigen Polymerenlösungen wird durch Zusatz der nicht-ionischen Tenside erhöht, doch ist der Effekt nicht so erheblich als durch Zusatz von ionischen Tensiden bei höheren Temperaturen. Die Lösungen von hydrophoben Polymeren und nicht-ionischen Tensiden zeigen andere Solubilisationsvermögen als die der Tensidlösungen allein. Diese Erscheinungen werden durch die Bindung der Tenside an die hydrophoben Teile der Polymeren oder, mit anderen Worten, durch Komplexbildung erklärt.
mit 7 Abbildungen und 1 Tabelle 相似文献
Summary Some water-insoluble copolymers of polyvinylalcohol-acetate are solubilized transparently in aqueous solutions of non-ionic surfactants. From viscosity measurements it is concluded that the copolymer chains, which areshrunken in water, are uncoiled in the aqueous non-ionic surfactant solutions. Clouding points of the aqueous polymer solutions are increased by addition of the non-ionic surfactants, but the effect is less remarkable than by ionic surfactants, especially at higher temperatures.The mixed solution of a hydrophobic copolymer and a non-ionic surfactant has a solubilisation power which is different from that of the surfactant alone. These phenomena are explained by binding of the non-ionic surfactants to the hydrophobic parts of the copolymers, i. e., by the complex formation.
mit 7 Abbildungen und 1 Tabelle 相似文献
782.
Toshio Tanaka Seizi Kurozumi Takeshi Toru Makiko Kobayashi Shuji Miura Sachio Ishimoto 《Tetrahedron》1977,33(10):1105-1112
Regiospecific α-acylation of β-alkenylated enolates generated by conjugate addition of lithium organocuprates to α,β-unsaturated ketones is described. Several new 7-oxoprostaglandin analogues, 7-oxoprostaglandin E1 (18), 11-deoxy-7-oxoprostaglandin E1 (23), and their 15-epi enantiomers 17 and 22, were synthesized by conjugate addition-acylation method. From optically active 4(R) -t - butyldimethylsiloxycyclopent - 2 - en - 1 - one (R-11), 7-oxoprostaglandin E1 (18) was synthesized. Determination of the absolute configuration of 11-deoxy-7-oxoprostaglandin E1 (23) and its 15-epi enantiomer (22) on the basis of CD study is described. Successful acylation of β-alkenylated lithium copper enolates with reactive acylating agents such as thiol esters and N-acyl imidazole as well as acyl halides is described. 相似文献
783.
784.
Kadish KM Autret M Ou Z Akiba Ky Masumoto S Wada R Yamamoto Y 《Inorganic chemistry》1996,35(19):5564-5569
The following five antimony(V) tetraphenylporphyrins with sigma-bonded antimony-carbon bonds were synthesized: [(TPP)Sb(CH(3))(2)](+)PF(6)(-), [(TPP)Sb(OCH(3))(OH)](+)PF(6)(-), [(TPP)Sb(CH(3))(OH)](+)ClO(4)(-), [(TPP)Sb(CH(3))(OCH(3))](+)ClO(4)(-), and [(TPP)Sb(CH(3))(F)](+)PF(6)(-). Each compound is stable toward air and moisture and has a high melting point (>250 degrees C). The electrochemistry and spectroelectrochemistry of these sigma-bonded porphyrins were examined in benzonitrile or dichloromethane containing 0.1 M tetrabutylammonium perchlorate as supporting electrolyte and the data compared to those for three previously synthesized OEP derivatives containing similar sigma-bonded and/or anionic axial ligands. Each porphyrin shows two reversible reductions and up to a maximun of one oxidation within the potential window of the solvent. Spectroelectrochemical data indicate formation of a porphyrin pi anion radical upon the first reduction as do ESR spectra of the singly reduced species. However, a small amount of the Sb(III) porphyrin products may be generated via a chemical reaction following electron tranfer. An X-ray crystallographic analysis of [(TPP)Sb(CH(3))(F)](+)PF(6)(-) is also presented: monoclinic, space group C2/c, Z = 8, a = 24.068(5) ?, b = 19.456(4) ?, c = 18.745(3) ?, beta = 94.69(2) degrees, R = 0.056. 相似文献
785.
Sumanta Bhattacharya Takanori Shimawaki Xiaobin Peng A. Ashokkumar Shuji Aonuma Takahide Kimura Naoki Komatsu 《Chemical physics letters》2006,430(4-6):435-442
We have tailored some interesting mono- and diporphyrins, viz., 5, 10, 15, 20-tetrakis(octadecyloxyphenyl)-21H,23H-porphyrin (TP), 5, 15-bis(3, 5-dioctylphenyl)-2, 8, 12, 18-tetramethyl-3, 7, 13, 17-tetradodecyl-21H,23H-porphyrin (AP) and 1, 3-bis(10′,20′-diundecyl-21′H,23′H-porphyrin-5′-yl)benzene (DP) as host molecules to study their complexation behavior with C60 and C70. Fluorescence spectroscopic measurements showed that emission of TP, AP and DP in toluene was quenched in the presence of C60 or C70. Large binding constants (K) in the magnitude of 1.5 × 104 dm3 mol−1 have been obtained for the 1:1 complexes of C70 with TP, AP and DP. However, the C60 complexes have exhibited 8.5 times smaller K compared to C70 complexes. Ab initio theoretical calculations give a good support in favor of strong complexation between C70 and porphyrins. 相似文献
786.
M Miwa T Ishikawa H Eda M Ryu K Fujimoto Y Ninomiya I Umeda K Yokose H Ishitsuka 《Chemical & pharmaceutical bulletin》1990,38(4):998-1003
N4-Trimethoxybenzoyl-5'-deoxy-5-fluorocytidine (Ro 09-1390), a new prodrug of 5'-deoxy-5-fluorouridine (5'-dFUrd), was synthesized for the purpose of finding a drug with less intestinal toxicity than the parent compound. The present study compared the antitumor activity and immunotoxicity of Ro 09-1390 with those of 5'-dFUrd, 5-fluorouracil (5-FUra) and tegafur in various transplantable tumor models. The antitumor efficacy of Ro 09-1390 was comparable to 5'-dFUrd and these two agents were much more effective than the others. However, Ro 09-1390 was much less toxic to the intestinal tract and less immunosuppressive in both humoral and cellular immune reactions than 5'-dFUrd. Consequently, Ro 09-1390 showed higher therapeutic indices and higher efficacy than 5'-dFUrd at high dosages. The antitumor spectrum of Ro 09-1390 was somewhat different from that of 5'-dFUrd, though it shows the efficacy after it converts to 5'-dFUrd. The activity of Ro 09-1390 was partly associated with cytidine deaminase in the tumors treated. Ro 09-1390 appeared to be more effective against tumors with a high concentration of the enzyme by which the major metabolite 5'-deoxy-5-fluorocytidine (5'-dFCyd) is metabolized to 5'-dFUrd. 相似文献
787.
Iwaoka M Komatsu H Katsuda T Tomoda S 《Journal of the American Chemical Society》2002,124(9):1902-1909
To evaluate weak intramolecular nonbonded Se...F interactions recently characterized for a series of o-selenobenzyl fluoride derivatives (Iwaoka et al., Chem. Lett. 1998, 969-970), the temperature dependence of the nuclear spin coupling between Se and F (J(Se...F)) was investigated for 2-(fluoromethyl)phenylselenenyl cyanate (1a) and bis[2-(fluoromethyl)phenyl] diselenide (1e) in CD2Cl2 and CD3CN. A significant increase in the magnitude of J(Se...F) was observed for both 1a and 1e upon lowering temperature, whereas the values of J(Se...F) for the corresponding trifluoromethyl compounds slightly reduced or remained unchanged at low temperatures. Application of the rapid equilibrium model between two possible conformers revealed that conformer A with an intramolecular Se...F interaction is more stable in enthalpy (DeltaH) by 1.23 kcal/mol for 1a (in CD2Cl2) and by 0.85 and 0.83 kcal/mol for 1e (in CD2Cl2 and CD3CN, respectively) than conformer B, which does not have close Se...F contact. The negligible solvent effects for 1e suggested marginal electrostatic nature of the Se...F interactions. Instead, importance of the n(F) -->sigma*(Se-X) orbital interaction was suggested by quantum chemical (QC) calculations and the natural bond orbital (NBO) analysis. 相似文献
788.
In situ chemical aminoacylation with amino acid thioesters linked to a peptide nucleic acid 总被引:1,自引:0,他引:1
Ninomiya K Minohata T Nishimura M Sisido M 《Journal of the American Chemical Society》2004,126(49):15984-15989
tRNA-specific chemical aminoacylation was achieved with nonnatural amino acids. A nonnatural amino acid was activated as a thioester derivative, and the latter was linked through a spacer to the N-terminal of a 9-mer peptide nucleic acid that is complementary to the 3'-terminal region of yeast phenylalanine tRNA. Efficient aminoacylation was observed when the amino acid thioester-spacer-PNA conjugate was mixed with the tRNA. The PNA-assisted aminoacylation was also successful in an Escherichia coli in vitro protein synthesizing system that contained an orthogonalized tRNA. The in situ aminoacylation/in vitro translation gave a mutant protein in which the nonnatural amino acid was incorporated into the position directed by a CGGG 4-base codon/anticodon pair. 相似文献
789.
Okawara T Ehara S Kagotani H Okamoto Y Eto M Harano K Yamasaki T Furukawa M 《The Journal of organic chemistry》1996,61(12):4125-4129
Hydrazinoethanols 1 were reacted with aldehydes 2 and 6 and glutaraldehyde (14) in aqueous solution to give dioxatetraazaperhydroanthracenes 3, 7, 12, and 13 and -perylenes 15 in yields of 19-88 and 42-72%, respectively. Compounds 3, 7, 12, and 15 were deduced by (13)C-NMR spectra to have two C(2) symmetry axes, while compound 12 was shown to have a symmetry axis by X-ray crystallography. The most favorable stereoisomers were consistent with predictions obtained by the semiempirical molecular orbital method AM1. The structure of compound 15 was confirmed by X-ray crystallography. 相似文献
790.