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181.
Sekizaki H Itoh K Shibuya A Toyota E Kojoma M Tanizawa K 《Chemical & pharmaceutical bulletin》2008,56(5):688-691
Two series of inverse substrates, p- and m-(amidinomethyl)phenyl esters derived from N-(tert-butyloxycarbonyl)amino acid, were prepared as acyl donor components for enzymatic peptide synthesis. They were found to be readily coupled with an acyl acceptor such as L-alanine p-nitroanilide to produce dipeptide. An alpha-aminoisobutyric acid containing dipeptide was especially obtained in satisfactory yield. Streptomyces griseus trypsin was a more efficient catalyst than the bovine trypsin. The optimum condition for the coupling reaction was studied by changing the organic solvent, pH, and acyl acceptor concentration. It was found that the enzymatic hydrolysis of the resulting product was negligible. 相似文献
182.
Copper and manganese in water samples at levels at or below the μg kg?1 level are determined by graphite-furnace atomic absorption spectrometry, after coprecipitation with 8-quinolinol followed by direct measurements on precipitate in a specially-designed furnace. The two metal ions are coprecipitated quantitatively in the pH range 7.0–8.5 with magnesium ions as carrier. The detection limits for copper and manganese are 12 and 14 ng kg?1, respectively, for 300-ml portions of water samples analyzed. 相似文献
183.
Kenichiro Todoroki Tatsuki Nakano Yasuhiro Eda Kaname Ohyama Hideki Hayashi Daiki Tsuji Jun Zhe Min Koichi Inoue Naoki Iwamoto Atsushi Kawakami Yukitaka Ueki Kunihiko Itoh Toshimasa Toyo'oka 《Analytica chimica acta》2016
This study presents two simple and rapid methods for the quantification of therapeutic mAbs based on LC. Two mAbs (bevacizumab and infliximab) in plasma samples were purified using magnetic beads immobilized with a commercially-available idiotype antibody for each mAb. Purified mAbs were separated with HT-RPLC and detected with their native fluorescence. Using immunoaffinity beads, each mAb was selectively purified and detected as a single peak in the chromatogram. The HT-RPLC achieved good separation for the mAbs with sharp peaks within 20 min. The calibration curves of the two mAbs ranged from 1 to 20 μg mL−1 (bevacizumab) and 1–10 μg mL−1 (infliximab), and they had strong correlation coefficients (r2 > 0.998). The LOD of bevacizumab and infliximab was 0.07 and 0.15 μg mL−1, and the LLOQ of bevacizumab and infliximab was 0.12 and 0.25 μg mL−1, respectively. Thus, the sensitivities were sufficient for clinical analysis. Immunoaffinity purification with HT-RPLC produced a selective and accurate bioanalysis without an LC-MS/MS instrument. Both methods could become general-purpose analytical methods and complement the results obtained with conventional LBA. 相似文献
184.
Koji Kubono Kunihiko Yokoi 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(9):o535-o537
The title compound, C18H18Cl4N2O2, crystallizes as monoclinic and orthorhombic polymorphs from CHCl3–CH3OH solution. In both polymorphic forms, the molecule lies on a crystallographic centre of inversion (at the piperazine ring centroid) and exhibits an intramolecular O—H...N hydrogen bond. In the monoclinic polymorph (space group P21/c), the molecules are linked by intermolecular C—H...Cl hydrogen bonds into a ribbon sheet built from R88(34) rings. In the orthorhombic polymorph (space group Pbcn), the molecules are linked by intermolecular C—H...O hydrogen bonds into a ribbon sheet of R66(34) rings. The sheets in the orthorhombic polymorph are crosslinked into a three‐dimensional framework by π–π stacking interactions. 相似文献
185.
Kimio Imaizumi Takashi Ono Itaru Natori Shinichi Sakurai Kunihiko Takeda 《Journal of Polymer Science.Polymer Physics》2001,39(1):13-22
We report the effect of microphase‐separated structure on the mechanical and thermal properties of several poly(1,3‐cyclohexadiene‐block‐butadiene‐block‐1,3‐cyclohexadiene) triblock copolymers (PCHD‐block‐PBd‐block‐PCHD) and of their hydrogenated derivatives: poly(cyclohexene‐block‐ethylene/butylene‐block‐cyclohexene) triblock copolymers (PCHE‐block‐PEB‐block‐PCHE). Both mechanical strength and heat‐resistant temperature (ex. Vicat Softening Temperature: VSPT) tended to increase with an increase in the 1,3‐cyclohexadiene (CHD)/butadiene ratio. On the other hand, heat resistance of the hydrogenated block copolymer was found to be higher than that of the unhydrogenated block copolymer. However, the mechanical strength was lower than those of the unhydrogenated block copolymer with the same ratio of CHD to butadiene. To clarify the relationship between the higher order structures of those block copolymers and their properties, we observed the microphase‐separated structure by transmission electron microscope (TEM). Hydrogenated block copolymers were found to have more finely dispersed microphase‐separated structures than those of the unhydrogenated block copolymers with the same CHD/Bd ratios through the use of TEM and the small‐angle X‐ray scattering (SAXS) technique. Those results indicated that the segregation strength between the PCHE block sequence and the PEB block sequence increased, depending on hydrogenation of the unhydrogenated precursor. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 13–22, 2001 相似文献
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188.
Masashi Mizuno Kunihiko Fujii Kiyoshi Tomioka 《Angewandte Chemie (International ed. in English)》1998,37(4):515-517
The astonishingly simple chiral ligand 1 was used in the first asymmetric variant of the Horner–Wadsworth–Emmons reaction. The products of olefination of 4-substituted cyclohexanones with lithium phosphanates arise via the resulting hydroxyphosphonates, which are present in high enantiomeric excess (see scheme below). R=aryl, vinyl; R′=Me, tBu, Ph. 相似文献
189.
Henri Doucet Takeshi Ohkuma Kunihiko Murata Tohru Yokozawa Masami Kozawa Eiji Katayama Anthony F. England Takao Ikariya Ryoji Noyori 《Angewandte Chemie (International ed. in English)》1998,37(12):1703-1707
A turnover number (TON) of 2 400 000 and a turnover frequency (TOF) of 63 s−1 are achieved with the chiral RuII complex 1 (R=p-CH3C6H4) in the asymmetric hydrogenation of acetophenone. Carbonyl-selective asymmetric hydrogenation of α,β-unsaturated ketones proceeds in the presence of these RuII catalysts, and 4-substituted cyclohexanones are selectively converted into cis alcohols. 相似文献
190.