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151.
Akane Agui Hiroshi Sakurai Takuro Tamura Toshitaka Kurachi Masahito Tanaka Hiromichi Adachi Hiroshi Kawata 《Journal of synchrotron radiation》2010,17(3):321-324
An application of magnetic Compton scattering as a new tool to measure a spin‐specific magnetic hysteresis (SSMH) loop is introduced and its validity demonstrated. The applied magnetic field dependence of the integrated intensity of magnetic Compton scattering spectra, which reflect only the spin‐dependent magnetic properties of magnetically active electrons, was interpreted as the spin‐specific hysteresis. The spin magnetization of amorphous Tb33Co67 film was observed and its SSMH loop exhibited qualitative agreement with the ordinal magnetic hysteresis loop measured using a conventional vibrating sample magnetometer. 相似文献
152.
Yukio Hitotsuyanagi Masahito Hirai Masumi Odagiri Miho Komine Tomoyo Hasuda Haruhiko Fukaya Koichi Takeya 《化学:亚洲杂志》2019,14(1):205-215
Two RA‐series bicyclic hexapeptides, RA‐XXV ( 4 ) and RA‐XXVI ( 5 ), which have no N‐methyl group at Tyr‐5, were isolated from the roots of Rubia cordifolia L. Their amino acid compositions and sequences were determined by interpretation of MS, and 1D and 2D NMR data and their relative structures were elucidated by XRD analysis of 4 and RA‐XXVI acetate ( 6 ). The absolute stereochemistry of 4 was established by the total synthesis of 4 , and that of 5 , by the chemical correlation with 4 . Peptides 4 and 5 exhibited cytotoxicity toward human promyelocytic leukemia HL‐60 (IC50=0.062 and 0.066 μm , respectively) and human colonic carcinoma HCT‐116 (IC50=0.028 and 0.051 μm , respectively) cell lines. Analysis of the conformational structures of 4 and 6 in the crystalline state and those of 4 and 5 in solution revealed that the N‐methyl group at Tyr‐5 functions to make this series of peptides preferentially adopt the active conformation. 相似文献
153.
Masahito Hayashi 《Communications in Mathematical Physics》2009,289(3):1087-1098
We construct a universal code for a stationary and memoryless classical-quantum channel as a quantum version of the universal coding by Csiszár and Körner. Our code is constructed utilizing a combination of irreducible representations, a decoder introduced through the quantum information spectrum, and the packing lemma. 相似文献
154.
M Kodera Y Kawahara Y Hitomi T Nomura T Ogura Y Kobayashi 《Journal of the American Chemical Society》2012,134(32):13236-13239
The conversion of peroxodiiron(III) to high-spin S = 2 oxodiiron(IV) via reversible O-O bond scission in a diiron complex with a bis-tpa dinucleating ligand, 6-hpa, has been characterized by elemental analysis; kinetic measurements for alkene epoxidation; cold-spray ionization mass spectrometry; and electronic absorption, M?ssbauer, and resonance Raman spectroscopy to gain insight into the O(2) activation mechanism of soluble methane monooxygenases. This is the first synthetic example of a high-spin S = 2 oxodiiron(IV) species that oxidizes alkenes to epoxides efficiently. The bistability of the peroxodiiron(III) and high-spin S = 2 oxodiiron(IV) moieties is the key feature for the reversible O-O bond scission. 相似文献
155.
Masahito Ochiai Prof. Dr. Masao Naito Kazunori Miyamoto Prof. Dr. Satoko Hayashi Prof. Dr. Waro Nakanishi Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(29):8713-8718
Exposure of sulfides and sulfoxides to trifluoromethanesulfonylimino(aryl)‐λ3‐bromane in dichloromethane at 0 °C results in a facile transfer of the sulfonylimino group to sulfur atoms and affords N‐triflylsulfilimines and ‐sulfoximines in high yields under transition‐metal‐free conditions. Imination of (R)‐methyl p‐tolyl sulfoxide proceeded with predominant retention of configuration at the stereogenic sulfur center. The Hammett plot afforded ρ values of ?0.58 for para‐substituted thioanisoles and ?0.49 for their equivalent sulfoxides, which suggests a buildup of positive charge on the sulfur atoms of sulfides and sulfoxides in the transition state. Calculations suggest a bimolecular nucleophilic‐substitution mechanism on the negatively charged nitrogen atom of the sulfonylimino‐λ3‐bromane, which involves the attack of a sulfide from the opposite side to bromine(III). 相似文献
156.
Gridnev ID Watanabe M Wang H Ikariya T 《Journal of the American Chemical Society》2010,132(46):16637-16650
The mechanism of Michael addition reactions of 1,3-dicarbonyl compounds to cyclic enones catalyzed by bifunctional Ru catalysts bearing N-sulfonylated (R,R)-DPEN ligands (DPEN = (R,R)-1,2-diphenylethylenediamine) was studied by NMR and DFT computational analyses. NMR investigation of the stoichiometric reactions of chiral amido Ru complexes, Ru(N-sulfonylated dpen)(η(6)-arene) 1a-c, with dimethyl malonate 2 and β-keto ester 3 revealed that at decreased temperatures deprotonation proceeds in a stereoselective manner to provide amine complexes. The reaction with malonic ester 2 provided exclusively C-bound amino Ru complexes 6a,c, while the reaction of β-keto ester 3 gave an equilibrium mixture of rapidly interconverting C- and O-bound complexes. The structures of C-bound Ru complex 6c and O-bound Ru complex 9c were determined by single crystal X-ray analysis. A computational study showed that the enatioselective C-C bond formation proceeds through intermediate formation of chelating ion pairs that coordinate a molecule of enone via the Ru metal center producing a highly organized environment for the C-C bond formation, yielding selectively only one enantiomer of the product. Systematic study of a series of the catalyst-substrate combinations revealed that the experimentally observed sense of enantioselection was consistently explained by computational analysis. The tendency of increasing ee with the bulk of the coordinated arene in Ru complex is reproduced computationally by changes in the difference of either ZPPE-corrected energies or Gibbs free energies for S- and R-pathways. 相似文献
157.
A novel palladium- and copper-catalyzed one-pot multicomponent synthesis of hetero α,α'-dimers of heterocycles via Sonogashira coupling and double cyclization cascade involving imine formation has been developed. This reaction cascade proceeded under mild conditions, providing a powerful synthetic tool for the assembly of π-conjugated systems with a combination of palladium-catalyzed post-direct C-H bond arylations. 相似文献
158.
Kazuaki Ito Ryosuke Nomura Takuya Fujii Masahito Tanaka Tomoaki Tsumura Hiroyuki Shibata Takeshi Hirokawa 《Analytical and bioanalytical chemistry》2012,404(8):2513-2517
A method was developed for determination of inorganic anions, including nitrite (NO 2 ? ), nitrate (NO 3 ? ), bromide (Br?), and iodide (I?), in seawater by ion chromatography (IC). The IC system used two dilauryldimethylammonium bromide (DDAB)-coated monolithic ODS columns (50?×?4.6?mm i.d. and 100?×?4.6?mm i.d.) connected in series for separation of the ions. Aqueous NaCl (0.5?mol/L; flow rate, 3?mL/min) containing 5?mmol/L phosphate buffer (pH 5) was used as the eluent, and detection was with a UV detector at 225?nm. The monolithic ODS columns were coated and equilibrated with a 1-mmol/L DDAB solution (in H2O/methanol, 90:10 v/v). The hydrophilic ions (NO 2 ? , NO 3 ? , and Br?) were separated within 3?min and the retention time of I? was 16?min. No interferences from matrix ions, such as chloride and sulfate ions, were observed in 35?‰ artificial seawater. The detection limits were 0.6?μg/L for NO 2 ? , 1.1?μg/L for NO 3 ? , 70?μg/L for Br?, and 1.6?μg/L for I? with a 200-μL sample injection. The performance of the coated columns was maintained without addition of DDAB in the eluent. The IC system was successfully applied to real seawater samples with recovery rates of 94–108?% for all ions. Figure
The hydrophilic ions (NO 2 ? , NO 3 ? , and Br?) and I? in seawater was determined by a single run using the IC system consisting of two dilauryldimethylammonium bromide (DDAB)-coated monolithic ODS columns (50?×?4.6?mm i.d. and 100?×?4.6?mm i.d.) connected in series, NaCl (0.5?mol/L; flow rate, 3?mL/min) containing 5?mmol/L phosphate buffer (pH 5) as the eluent, and a UV detector (225?nm). No interferences from matrix ions, such as chloride and sulfate ions, were observed in 35?‰ artificial and real seawaters. 相似文献
159.
Okamoto K Mashida A Watanabe M Ohe K 《Chemical communications (Cambridge, England)》2012,48(29):3554-3556
An unprecedented nickel-catalysed disproportional reaction of 2,3-diaryl-2H-azirines forming azabutadienes and aromatic nitriles was discovered. This reaction involves the cleavage of two bonds of the 2H-azirine framework, which provides a novel type of transformation of 2H-azirines. 相似文献
160.
Okamoto K Watanabe M Murai M Hatano R Ohe K 《Chemical communications (Cambridge, England)》2012,48(25):3127-3129
A gallium-catalysed, direct cyanation reaction of aromatic and heteroaromatic C-H bonds with cyanogen bromide was developed as a practical synthetic method for the preparation of aromatic nitriles. 相似文献