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101.
Akiko Tanaka Haruhiko Yashiro Asako Ishigaki Hisao Murai 《Applied magnetic resonance》2010,37(1-4):581-593
The photochemical reactions of methylene blue (MB) included in water-soluble sulfonated calix[n]arenes (n = 4, 6, 8) are studied using a time-resolved electron spin resonance method. The chemically induced dynamic electron polarization (CIDEP) spectra show the formation of the complex radical pair composed of the MB monocation radical and calixarene (phenoxyl-type) radical. The lifetime and broadened spectral shape are dependent on the size of the calixarene and are due to the longitudinal and transverse relaxation mainly induced by the tumbling motion of the radical pair with the spin dipole–dipole interaction. The pair dissociates in a few hundreds of nanoseconds in cases of n = 6 and 8. 相似文献
102.
Sato S Tsunoda M Suzuki M Kutsuna M Takido-uchi K Shindo M Mizuguchi H Obara H Ohya H 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,71(5):2030-2039
Various hybrid compounds comprised of two types of nitroxide radicals and either a pentamethine (Cy5) or trimethine cyanine (Cy3) were synthesized. The nitroxide radicals were linked either via an ester-bond to one or two N-alkyl carboxyl-terminated groups of Cy5, or via two amido-bonds (aminocarbonyl or carbonylamino group) to the 5-position of the indolenine moieties of Cy5 and Cy3. Changes in fluorescence and ESR intensities of the hybrid compounds were measured before and after addition of Na ascorbate in PBS (pH 7.0) to reduce the radicals. Among the hybrid compounds synthesized, those that linked the nitroxide radicals via an aminocarbonyl residue at the 5-position of the indolenine moieties on Cy5 and Cy3 exhibited a 1.8- and 5.1-fold increase in fluorescence intensity with the reduction of the nitroxide segment by the addition of Na ascorbate, respectively. In contrast, fluorescence intensity was not enhanced in the other hybrid compounds. Thus, the hybrid compounds which exhibited an increase in fluorescent intensity with radical reduction can be used in the quantitative measurement of reducing species such as Fe(2+) and ascorbic acid, and hydroxyl radicals. Because these hybrid compounds have the advantage of fluorescing at longer wavelengths-661 (Cy5) or 568 (Cy3)nm, respectively, they can be used to measure radical-reducing species or radicals either in solution or in vivo. 相似文献
103.
Akihiro Hirao Shunichi Sato Daizoh Saitoh Nariyoshi Shinomiya Hiroshi Ashida Minoru Obara 《Photochemistry and photobiology》2010,86(2):426-430
For efficient antibacterial photodynamic therapy for wounds, information on the distribution of a photosensitizer in tissue is important, but conventional fluorescence measurement does not provide depth-resolved information. We previously proposed in vivo photoacoustic (PA) depth profiling of a photosensitizer, but the contrast of PA signals was not sufficiently high, mainly due to light absorption by blood in tissue. In this study, we performed dual-wavelength PA measurement; green light and red light were used to excite blood and photosensitzer, respectively, and the former signal was subtracted from the latter signal to compensate a blood-associated component. Methylene blue or porfimer sodium solution was injected into subcutaneous tissue in rats with deep dermal burn and two-dimensional PA measurement was performed. The signal subtraction diminished not only the signal originating from blood but also the signal originating from the stratum corneum and acoustic reflection noise, creating a high-contrast PA image. The distribution of PA signals was confirmed to coincide well with the distribution of photosensitizer-originating fluorescence measured for tissue biopsied after the PA measurement, demonstrating the validity of this method for in vivo photosensitizer dosimetry. On the basis of this method, temporal behaviors of two photosensitizers were compared. 相似文献
104.
T. Sumiyoshi Y. Ninomiya H. Ogasawara M. Obara H. Tanaka 《Applied Physics A: Materials Science & Processing》1994,58(5):475-479
Organic polymer (PES: PolyEther Sulphone and PEEK: PolyEther Ether Ketone) ablation with oscillation-line selected TEA CO2 lasers is successfully demonstrated. With different irradiation conditions the ablative etch-rate slopes were varied, which means that the ablation process is dependent on the ablation conditions such as incident laser intensity and ambient gas. In perforation processing of the PEEK film, the TEA CO2 laser had a higher etch rate of 42 m/pulse at a fluence of 70 J/cm2 in vacuum than the XeCl laser. 相似文献
105.
Toshiaki Morimoto Nobuhiro Obara Iku Yoshida Kiyoshi Tanaka Toshiyuki Kan 《Tetrahedron letters》2007,48(17):3093-3095
New axially chiral P,O,N-type ligands bearing both a diphenylphosphino group and 2-(dialkylamino)ethyloxy (or 2-pyridylmethyloxy) groups were designed and prepared along with P,O,O-type ligands by employing an easily available chiral component, (R)-2-hydroxy-2′-diphenylphosphinyl-1,1′-binaphthyl. Among the ligands the simplest P,O,N-type one bearing a 2-(dimethylamino)ethyloxy group was found to be the most efficient in copper-catalyzed enantioselective conjugate addition of diethylzinc to a cyclic enone, 2-cyclohexen-1-one, providing high enantioselectivity up to 99% ee. 相似文献
106.
Guo Qunhui Haruhiko Ohya Yuan Xuejing Chen Liankai Huang Jicai 《Journal of membrane science》1995,100(3):217-228
Blends of high cyanoethylated cellulose (HCEC) (Ds = 2.5) and cellulose triacetate (CTA) (Ds = 2.8) were prepared for evaluation as ultrafiltration membranes. The rejection Ra and water permeability (Pw) of these membranes with respect to bovine serum albumin (BSA), were measured with the variations in composition and conditions of preparation. It was possible to define the reaction conditions and compositions that offered optimum performance with respect to Ra and Jw, and resistance to microbial degradation as well as acid and alkali hydrolysis. The morphology of membrane thereby obtained was characterized by scanning electron microscopy (SEM). The UF membrane cast from a solution of 1,4-dioxane: 12.5 g, acetone: 12.5 g, HCEC: 1.5 g, CTA: 3 g and PEG (MW = 1000): 10.5 g showed the optimum performance of Pw = 10 × 10−10 m3/(m2 s Pa), BSA Rejection (Ra) = 99%, (Jw = 17.3 m3/(m2 day) at ΔP = 0.2 MPa) and a molecular weight cut off at 4.9 × 104 Da. After immersion in mud for 170 days, reduction of Ra was only 8% for UF membrane containing 10 wt% HCEC blend, and was not observed to be obviously different from the membrane containing more than 30 wt% HCEC blend. The higher permeability and rejection of blend membrane may be attributable to the network structure formed via CTA and HCEC penetration. 相似文献
107.
Noritaka Abe Haruhiko Matsuda Yoshikazu Sugihara Akikazu Kakehi 《Journal of heterocyclic chemistry》1996,33(4):1323-1331
Reaction of 2-amino-1-azaazulene with phenyl isocyanate gave 3-phenyl-2H-3,4-dihydro-1,3,4a-triazabenz[5,4-a]azulene-2,4-dione. Reactions of 2-alkylamino-1-azaazulenes with aryl isocyanates gave 2-(N-ethyl-N′-arylureido)-1-azaazulenes initially, which rearranged to N-aryl-2-alkylamino-1-azaazulene-3-carboxamides and successive reaction with another molar amount of aryl isocyanate furnished uracil-fuzed 1-azaazulenes. Reaction of 2-piperidino-1-azaazulene with aryl isocyanate gave N-aryl-2-piperidino-1-azaazulene-3-carboxamide. Reaction of 2-(substituted amino)-1-azaazulenes with chlorosulfonyl isocyanate gave 3-cyano- and 3-chloro-2-(substituted amino)-1-azaazulenes. 相似文献
108.
Yashiro H White RC Yurkovskaya AV Forbes MD 《The journal of physical chemistry. A》2005,109(26):5855-5864
A comprehensive high resolution electron paramagnetic resonance (EPR) characterization of the l-methionine radical cation and its N-acetyl derivative in liquid solution at room temperature is presented. The cations were generated photochemically in high yield by excimer laser excitation of a water soluble dye, anthraquinone sulfonate sodium salt, the excited triplet state of which is quenched by electron transfer from the side chain sulfur atom of methionine or N-acetylmethionine. The radicals were detected by continuous wave (CW) time-resolved electron paramagnetic resonance (TREPR) spectroscopy at X-band (9.5 GHz) and Q-band (35 GHz) microwave frequencies. At pH values well below the pK(a) of the protonated amine nitrogen, the cation forms a dimer with another ground-state methionine molecule through a S-S three-electron bond. In basic solution, the lone pair on the nitrogen of the amino acid is available to make an intramolecular S-N three-electron bond with the side chain sulfur atom, leading to a five-membered ring structure for the cation. When the amino acid nitrogen is unsubstituted (methionine itself), rapid deprotonation to an aminyl radical takes place at high pH values. If the nitrogen is substituted (N-acetylmethionine), the cyclic structure is observed within its electron spin relaxation time at about 1 micros. Spectral simulation provides chemical shifts (g-factors) and hyperfine coupling constants for all structures, and isotopic labeling experiments strongly support the assignments. 相似文献
109.
The kinetics of the thermal decompositions of CaC2O4, SrC2O4 and BaC2O4 to their carbonates were studied by thermogravimetry at constant and at linearly increasing temperatures. Isothermally, the three oxalates decompose according to A1.43, R1.54 and R1 laws, respectively. Dynamically, the decompositions of the first two oxalates proceed in a similar way as under the isothermal conditions, whereas BaC2O4 decomposes according to a different law.Kinetic compensation laws were established for the decomposition of CaC2O4 and SrC2O4 under both isothermal and non-isothermal conditions. Such a compensation law is considered to result if correct kinetic model functionsF () are used when the isothermal and non-isothermal decompositions are regulated by the sameF().
Zusammenfassung Die Kinetik der thermischen Zersetzung von CaC2O4, SrC2O4 und BaC2O4 zu den entsprechenden Carbonaten wurde durch Thermogravimetrie bei konstanter und linear ansteigender Temperatur untersucht. Isotherm werden die drei Oxalate entsprechend A1.43, R1.54 bzw. R1 zersetzt. Dynamisch verläuft die Zersetzung der ersten zwei Oxalate auf ähnlichem Wege, während BaC2O4 nach einem davon verschiedenem Gesetz abgebaut wird. Kinetische Kompensationsgesetze wurden sowohl unter isothermen als auch unter nicht-isothermen Bedingungen für die Zersetzung von CaC2O4 und SrC2O4 ermittelt. Ein solches Kompensationsgesetz wird als Ergebnis eines solchen Vorgehens angesehen, bei dem richtige kinetische ModellfunktionenF() benutzt werden, wenn die nicht-isothermen Zersetzungen durch die gleichenF() bestimmt sind.
- , . , , A1.43, R1.54 · R1- , . , . F() «» , F().相似文献
110.
M. Kakehata R. Ueda H. Takada K. Torizuka M. Obara 《Applied physics. B, Lasers and optics》2000,70(7):S207-S213
Time-dependent polarization pulses are generated by combining two perpendicularly polarized, high-intensity laser pulses. The time evolution of the polarization state of the combined laser pulse is measured by the POLLIWOG technique. We observed changes in the polarization state while varying the relative delay. In order to investigate the effect of pulse combination on the ionization of atoms, the electron signals and the ion signals are measured by irradiating combinations of two perpendicularly polarized pulses or two parallel polarized pulses. With the two parallel polarized pulses, high-order fringe-resolved autocorrelations are obtained by measuring the time-integrated ion signals as a function of the time delay. When two perpendicularly polarized pulses are combined, the fringe period of the time-integrated electron signal as a function of the time delay is different from that of the time-integrated ion signal. This is due to the fact that the electron signal depends on the direction of the field vibration and the number of generated electrons. We also measured the electron energy distributions at different relative delays and confirmed that these depend on the polarization state of generated pulses. 相似文献