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111.
Yasuyuki Takeda Yusuke Mochizuki Yasumasa Matsuzaki Shoichi Katsuta 《Journal of inclusion phenomena and macrocyclic chemistry》2000,37(1-4):179-195
Formation constants of 1 : 1 19-crown-6(19C6) complexes with alkali metal ions weredetermined conductometrically at 25 °Cin acetonitrile(AN), propylene carbonate (PC), methanol, DMF, andDMSO. 19C6 always forms the most stable complex withK+. The selectivity order of 19C6 forheavy alkali metal ions isK+ > Rb+ > Cs+.The selectivity for Na+ varies withthe solvent; that for Li+ is the second lowest(AN, DMSO) or the lowest (PC). Transfer activity coefficients(SH
2 O) of19C6 from water to the nonaqueous solvents (S) weremeasured at 25 °C. The contributions of a methylenegroup and an ether oxygen atom to thelog SH
2 Ovalue of a crown ether wereobtained. The SH
2 Ovalues of the 19C6–alkali metal ion complexes(SH
2 O (ML+)) werecalculated, M+ and L denoting an alkali metal ionand a crown ether, respectively. For AN, PC, andCH3OH, although the M+ ion is more stronglysolvated by water than by AN, PC, or CH3OH, thelog SH
2 O (ML+) islarger than the correspondinglog SH
2 O (L)expect for the case of M+ = Li+.The higher lipophilicity of the19C6 complex ion is attributed to an enforcement ofthe hydrogen-bonded structure of water for the complexion caused by the greatly decreased hydrogen bondingbetween ether oxygen atoms and water uponcomplexation. For DMF and DMSO, thelog SH
2 O (ML+) is also greater thanthe correspondinglog SH
2 O (L).It was concluded from thisfinding that the unexpectedly lowest stability of the19C6 complex ion in water is due to the hydrogenbonding between 19C6 and water. The stabilities and thelog SH
2 Oof 19C6–alkali metal ion complexes were compared with those of 18C6complexes. 相似文献
112.
Tanaka Y Kasai Y Mochizuki S Wakisaka A Morita EH Kojima C Toyozawa A Kondo Y Taki M Takagi Y Inoue A Yamasaki K Taira K 《Journal of the American Chemical Society》2004,126(3):744-752
We have studied the interaction between metal ions and the metal ion-binding motif in hammerhead ribozymes, as well as the functions of the metal ion at the motif, with heteronuclear NMR spectroscopy. In this study, we employed model RNA systems which mimic the metal ion-binding motif and the altered motif. In Co(NH3)6(III) titrations, we observed large 1H and 31P chemical shift perturbations for the motif and found that outer-sphere complexation of Co(NH3)6(III) is possible for this motif. From the reinvestigation of our previous 15N chemical shift data for Cd(II) binding, in comparison with those of organometallic compounds, we conclude that Cd(II) can form an inner-sphere complex with the nucleobase in the motif. Therefore, the A9/G10.1 site was found to accept both inner-sphere and outer-sphere complexations. The Mg(II) titration for a slightly different motif from the A9/G10.1 site (G10.1-C11.1 to A10.1-U11.1) revealed that its affinity to Mg(II) was drastically reduced, although the ribozyme with this altered motif is known to retain enzymatic activities. This observation suggests that the metal ion at these motifs is not a catalytic center of hammerhead ribozymes. 相似文献
113.
Koizumi T Harada K Asahara H Mochizuki E Kokubo K Oshima T 《The Journal of organic chemistry》2005,70(21):8364-8371
Bicyclic 3aH-cyclopentene[8]annulene-1,4-(5H,9aH)-diones underwent three types of acid-induced transannular reactions, Michael cyclization, [3 + 2] cycloaddition, and Friedel-Crafts ipso-alkylation, depending on the cyclopentenone ring substituent (Me or Ph) and the position of [8]annulenone substituent as well as the nature of acids (BF3, MeSO3H, CF3SO3H). The Me-substituent permitted the Michael reaction for all acids used to give tricyclic diones by the activation of cyclopentenone carbonyl group. However, the Ph-substituent inhibited the Michael reaction for BF3 and MeSO3H but allowed the [3 + 2] cycloaddition and Friedel-Crafts reaction for CF3SO3H depending on the position of annulenone substituent. These CF3SO3H reactions exhibited the following novel rearrangements, affording 2-naphthalenone and 7-acenaphthylene derivatives, respectively. The factors that control the reaction mode of these transannular cyclizations were discussed in view of the constraint twist-boat conformation of [8]annulenone ring as well as the ring substituent effects on the intramolecular cyclization. In addition, these [8]annulenone rings were found to easily undergo the intramolecular [2 + 2] photocyclization to provide the tetracyclic cage compounds which exhibited the facile cycloreversion under the influence of acid. 相似文献
114.
Nomura E Katsuta K Ueda T Toriyama M Mori T Inagaki N 《Journal of mass spectrometry : JMS》2004,39(2):202-207
Mass spectrometry (MS) together with genome database searches serves as a powerful tool for the identification of proteins. In proteome analysis, mixtures of cellular proteins are usually separated by sodium dodecyl sulfate (SDS) polyacrylamide gel-based two-dimensional gel electrophoresis (2-DE) or one-dimensional gel electrophoresis (1-DE), and in-gel digested by a specific protease. In-gel protein digestion is one of the critical steps for sensitive protein identification by these procedures. Efficient protein digestion is required for obtaining peptide peaks necessary for protein identification by MS. This paper reports a remarkable improvement of protein digestion in SDS polyacrylamide gels using an acid-labile surfactant, sodium 3-[(2-methyl-2-undecyl-1,3-dioxolan-4-yl)methoxy]-1-propanesulfonate (ALS). Pretreatment of gel pieces containing protein spots separated by 2-DE with a small amount of ALS prior to trypsin digestion led to increases in the digested peptides eluted from the gels. Consistently, treatment of gel pieces containing silver-stained standard proteins and those separated from tissue extracts resulted in the detection of increased numbers of peptide peaks in spectra obtained by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOFMS). Hence the present protocol with ALS provides a useful strategy for sensitive protein identification by MS. 相似文献
115.
Kawamoto M Mochizuki H Ikeda T Iino H Hanna J 《The journal of physical chemistry. B》2005,109(19):9226-9230
Steady-state and transient photocurrent measurements were carried out to study the charge carrier transport properties of polymer liquid crystal (LC) containing oxadiazole (OXD) and amine moieties in the same side chain. The steady-state photocurrent measurement with asymmetric electrodes of ITO and Al and a short penetration depth of the illumination light indicated that both electrons and holes can be transported in this film. The transient hole photocurrent observed by time-of-flight (TOF) experiments was dispersive at room temperature. The hole drift mobility significantly depended on temperature and electric field and was determined to be 6.1 x 10(-8) cm2/Vs at a field of 9.1 x 10(5) V/cm. According to the disorder formalism, the Gaussian width of the density of states was determined to be 170 meV for holes. Despite the indication of possible electron transport in this film, we could not determine the electron mobility by TOF experiments due to strong dispersive photocurrent. We discuss the present charge transport properties of the film in relation to a large dipole attributed to an electrical push-pull structure of p-dimethylaminophenyl-substitited OXD moiety in polymer LC and its electroluminescent properties. 相似文献
116.
Naito H Ohsuki S Atsumi R Minami M Mochizuki M Hirotani K Kumazawa E Ejima A 《Chemical & pharmaceutical bulletin》2005,53(2):153-163
A series of novel 3-[4-phenyl-1-piperazinyl]-1-[5-methyl-1-(2-pyrimidinyl)-4-pyrazolyl]-1-trans-propenes and related compounds were synthesized and evaluated by their cytotoxic activity against several tumor cell lines in vitro and in vivo antitumor activity against some tumor models when administered both intraperitoneally and orally. Compounds with the 3-chloropyridin-2-yl group (9g) and the 3-fluoro-5-substituted phenylpiperazinyl group (29b, c, and e) showed significantly potent cytotoxicity by in vitro testing. Among them, the 3-cyano-5-fluorophenyl derivative (29b) exhibited potent antitumor activity against several tumor cells including human carcinoma without causing undesirable effects in mice. 相似文献
117.
Cadmium sulfo-selenide Cd1+y(SxSe1?x) single crystals were grown by the sublimation method under controlled partial pressures of sulfur and selenium. The partial pressure control was achieved by amounts of sulfur and selenium introduced in a closed growth tube. To control the deviation from stoichiometry y for the specified compositions x, the sum of chalcogen partial pressures Pps(=pS2+PSe2) was regulated, holding the partial pressure ratio () constant. The comp osition x of single crystals, grown with appreciable growth rate, was found to be the same one as the source specimen but the electrical conductivity changed extremely from 1 to 10-12 (ω cm)-1 with increasing Pps. Hall effect and thermally stimulated current (TSC) were also measured on the high and low conductivity specimens respectively and found to depend upon the controlled Pps. From these experimental results, it was confirmed that the deviation from stoichiometry y was effectively controlled. The transport rate was also precisely measured as a function of controlled Pps. 相似文献
118.
Keisuke Fukumura Yuki Narimatsu Shogo Moriwaki Eiko Iwakoshi-Ukena Megumi Furumitsu Kazuyoshi Ukena 《Molecules (Basel, Switzerland)》2021,26(19)
We previously identified a novel small hypothalamic protein, neurosecretory protein GL (NPGL), which induces feeding behavior and fat accumulation in rodents depending on their diet. In the present study, we explored the effects of NPGL on feeding behavior and energy metabolism in mice placed on a long-term high-fat diet with 60% calories from fat (HFD 60). Overexpression of the NPGL precursor gene (Npgl) over 18 weeks increased food intake and weight. The weekly weight gain of Npgl-overexpressing mice was higher than that of controls until 7 weeks from induction of overexpression, after which it ceased to be so. Oral glucose tolerance tests showed that Npgl overexpression maintained glucose tolerance and increased blood insulin levels, and intraperitoneal insulin tolerance tests showed that it maintained insulin sensitivity. At the experimental endpoint, Npgl overexpression was associated with increased mass of the perirenal white adipose tissue (WAT) and decreased mass of the epididymal WAT (eWAT), resulting in little effect on the total WAT mass. These results suggest that under long-term HFD 60 feeding, Npgl overexpression may play a role in avoiding metabolic disturbance both by accelerating energy storage and by suppressing excess fat accumulation in certain tissues, such as the eWAT. 相似文献
119.
120.