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71.
72.
73.
The distribution ratio (DM) of Pd(II) by the extraction with 2-methyl-8-quinolinol (HMQ) was determined using the supercritical carbon dioxide medium (SF-CO2) and organic solvent media such as perfluoro-methylcyclohexane, heptane, cyclohexane, carbon tetrachloride and benzene. From experimental results of the slopes of log DM versus pH plot and log DM versus HMQ concentration plot, the extracted species both in the SF-CO2 extraction (SFE) and the solvent extraction (SE) were determined to be Pd(MQ)2. The distribution constant of HMQ (KD,HMQ) in the SFE and SE systems were determined from the dependence of the distribution ratio of HMQ (DHMQ) on the pH. A linear relationship was observed between log KD,HMQ and the solubility parameter (δ) of the extraction medium based on the regular solution theory in both the SFE using SF-CO2 at the pressure of 8.5–40 MPa and the SE systems. The difference in the slope of the log KD,HMQ versus δ plot between the SFE and the SE systems is attributable to the extent of the specific interaction of the solute HMQ with the solvent molecules, i.e. CO2 molecules and the organic solvent molecules. The DM versus δ plot obtained under a given extraction condition using SF-CO2 (11–40 MPa) and organic solvents showed clear linearity. The DM obtained using SF-CO2 at relatively low pressure range from 8.5 to 11 MPa was independent of the pressure and the δ of SF-CO2, which coincides with the experimental fact that the solubility of Pd(MQ)2 in the SF-CO2 at 8.5–11 MPa was practically constant. 相似文献
74.
Yahachi Saito Motonori Inagaki Hisanori Shinohara
Hideo Nagashima
Masato Ohkohchi
Yoshinori Ando 《Chemical physics letters》1992,200(6):643-648The yields of toluene-soluble material from carbon soot depend on the buffer gas as well as the pressure. Helium was more effective for yielding fullerenes than argon, and the optimum pressure was 20 Torr, under which a maximum yield of about 13 wt% was obtained. C60 showed a maximum abundance at 20 Torr, while C70 and higher fullerenes (C76, C78 and C84) at a slightly higher pressure between 20 and 50 Torr. Raw soot was also studied by electron microscopy. The pressure dependence of the fullerene yield is discussed in terms of the cooling rate and diffusion of carbon vapor around the evaporation source. 相似文献
75.
Seiichiro Imamura Yo-ichi Taniguchi Yoshio Ikeda Saburo Hosokawa Hiroyoshi Kanai Hisanori Ando 《Reaction Kinetics and Catalysis Letters》2002,76(2):201-206
Three kinds of Ru/CeO2 catalysts were prepared. The mobility of the oxygen on Ru and their catalytic activity in the wet oxidation of acetic acid was investigated. Ru was present in the form of RuO2, and TPR experiment showed that the reaction, RuO2 + 2H2 Ru + 2H2O, took place in different temperature ranges depending upon the kind of the catalysts. The catalyst with easily reducible oxygen on Ru had high activity in wet oxidation, and the importance of the release of oxygen from Ru to the reactant was suggested. 相似文献
76.
Benten H Ohkita H Ito S Yamamoto M Tohda Y Tani K 《The Journal of chemical physics》2005,123(8):084901
Photoinduced intramolecular charge separation (CS) in a polar polymer glass, cyanoethylated pullulan (CN-PUL), was studied below the glass transition temperature (Tg=395 K). A series of three carbazole (Cz: donor)-cyclohexane (S: spacer)-acceptor (A: acceptor) molecules (Cz-S-A) was used as intramolecular donor-acceptor dyads. The photoinduced CS rate was evaluated by the fluorescence decay measurement at temperatures from 100 to 400 K. The CS rate (kCS) increased above 200 K even far below Tg where micro-Brownian motions of the whole polymer chain are frozen. Below 200 K, on the other hand, kCS showed weak dependence on temperature. The temperature dependence of kCS is discussed in terms of the dielectric relaxation time of the polymer matrix. Consequently, CS below Tg was well explained by a thermally nonequilibrium electron transfer (ET) formula above 200 K and by a two-mode quantum-mechanical ET formula below 200 K. The increase in kCS above 200 K is mainly caused by a thermally activated low-frequency matrix mode originating from the side-chain relaxation of polar cyano groups. The weak temperature dependence of kCS can be explained by a nuclear-tunneling effect caused by a high-frequency matrix mode (variant Planck's over 2piomegH=250 cm-1) and an intramolecular vibrational mode (variant Planck's over 2piomegaQ=1300 cm-1). The high-frequency mode of the polymer matrix was attributed to a vibrational or librational motion of polar groups in the CN-PUL glassy solid. 相似文献
77.
Tani K Tohda Y Takemura H Ohkita H Ito S Yamamoto M 《Chemical communications (Cambridge, England)》2001,(19):1914-1915
Syn- And anti-[3.3](3,9)carbazolophanes, which are suitable model compounds for sandwich and partial-overlap excimers, respectively, have been synthesized and characterized; the structures of both singlet and triplet carbazole excimer have been described. 相似文献
78.
Takanori Mizushima Kazumi Matsumoto Hironobu Ohkita Noriyoshi Kakuta 《Plasma Chemistry and Plasma Processing》2007,27(1):1-11
Plasma synthesis of ammonia was studied at atmospheric pressure using a dielectric-barrier-discharge-plasma reactor equipped
with a metal-loaded membrane-like alumina tube as a catalyst between the electrodes. Introducing the pure alumina into N2–H2 plasma resulted in an increase in the ammonia yield and the further improvement was achieved by loading the alumina with
Ru, Pt, Ni, and Fe. These results clearly demonstrate the catalytic effects of the alumina and the metals in the plasma reaction.
Temperature-programmed desorption and isotope exchange reaction of nitrogen revealed that plasma-excited N2 molecules were subjected to dissociative adsorptions mainly on the alumina to form atomic N(a) (The suffix “(a)” denotes
adsorbed species) species, which were converted into ammonia by H2 plasma. A role of the metals is considered to be acceleration of ammonia formation by the reaction of the alumina-adsorbed
N(a) atoms with plasma-activated hydrogen species. 相似文献
79.
Igarashi Y Kumazawa H Ohshima T Satomi H Terabayashi S Takeda S Aburada M Miyamoto K 《Chemical & pharmaceutical bulletin》2005,53(9):1088-1091
We describe the synthesis of 2-[(4-hydroxyphenyl)thio]-7-isopropoxy-5,6-dimethoxy-4H-chromen-4-one 2 from 3,4,5-trimethoxyphenol 6 via the key intermediate, 3-iodo-7-isopropoxy-5,6-dimethoxy-4H-chromen-4-one 3. An important feature of this synthetic scheme involves selective alkylation, which can be achieved by two different routes. One route involves the selective isopropylation of a triacetate derivative 4 under basic conditions. The second route employs the selective demethylation of a trimethoxy derivative 5 under acidic conditions followed by isopropylation. The product of these alternative routes, compound 3, is then converted to a capillarisin sulfur analogue 2 in a one-pot reaction via the imidazolyl intermediate 22. 相似文献
80.
[Reaction: see text]. Regio- and stereoselectivity in reactions of gem-difluorinated vinyloxiranes with heteronucleophiles were successfully controlled. Halogen atoms were introduced regioselectively at the allylic epoxide carbon with an inversion in stereochemistry using MgBr2*Et2O or Li2CuCl4 to produce anti-vic-halohydrine. The other diastereomers were obtained selectively using LiBr/AcOH or BCl3, and SN2' type products were formed selectively with excellent E preference by changing the reaction temperature. Moreover, a further investigation led us to find that a regio- and stereoselective SN2' addition of several Brnsted acids was dependent on the pKa values of the acids. Under strong acidic conditions, we exclusively obtained E allylic alcohols. 相似文献