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51.
Bare G. Jacques PH. Hubert J. B. Rikir R. Thonart PH. 《Applied biochemistry and biotechnology》1991,28(1):445-456
Applied Biochemistry and Biotechnology - The ability of the yeastSaccharomyces cerevisiae to bioconvert stereo-selectively octyl-4-chloroacetoacetate (OCA) into the corresponding chiral alcohol,... 相似文献
52.
J. Bystricky P. Chaumette J. Deregel J. Fabre F. Lehar A. De Lesquen L. Van Rossum J.M. Fontaine J. Gosset F. Perrot C.A. Whitten J. Ball PH. Chesny C.R. Newsom J. Yonnet T. Niinikoski M. Rieubland A. Michalowicz S. Dalla Torre-Colautti 《Nuclear Physics B》1985,262(4):727-743
The spin correlation parameter Aoonn and the analyzing powers Aoono and Aooon were measured simultaneously, in the energy range 0.5–0.8 GeV and in the angular region 40°–80° CM. The experiment used the polarized proton beam of SATURNE II and the Saclay frozen spin polarized target. 相似文献
53.
54.
The first 3-ethylenimino-1,2,4-triazines ( 9 ) have been synthesized from the corresponding 3-(β-chloroethyl)amino-1,2,4-triazines ( 8 ). In addition some 2,3-dihydroimidazo[1,2-b]-1,2,4-triazines and imidazo[1,2-b]-1,2,4-triazines were obtained. The stability, properties and potential therapeutic value of these compounds are discussed. 相似文献
55.
Anthony V. Galanti Franic Liotta Brian T. Keen Daniel A. Scole 《Journal of polymer science. Part A, Polymer chemistry》1982,20(1):233-239
Members of a series of N,N′-alkylene bisitaconamic acids were synthesized from the reaction between itaconic anhydride and a homologous group of aliphatic diamines with the general formula H2N (CH2)n NH2, where n = 4–12. Cyclodehydration of the acids in toluene gave the isomeric imides: bisitaconimide, biscitraconimide, and citra-itaconimide. The isomeric imides were isolated, purified, and characterized for each diaminoalkane studied. 相似文献
56.
Determination of titanium dioxide in foods using inductively coupled plasma optical emission spectrometry 总被引:4,自引:0,他引:4
Titanium dioxide is a common food additive of increasing interest in dietary intake studies and dietary exclusion studies. Food labelling for titanium dioxide is imprecise so a method was developed for its rapid determination in foods using acid digestion and inductively coupled plasma optical emission spectrometry (ICPOES). Twenty-five foods thought to contain titanium dioxide were obtained. Based on preliminary digestion studies, samples (500 mg) were digested in 18 mol l-1 H2SO4 at 250 degrees C for 1 h and then diluted to 5.9 mol l-1 H2SO4 before determination of titanium by ICPOES at 336.121 nm. Emission intensity was suppressed by H2SO4 so standards were matched for acid concentration. Titanium dioxide embedded in gelatine was used to assess accuracy. A standard reference material of known titanium concentration and six foods of known titanium dioxide content were used as external reference materials. Limits of detection were 2-7.5 ppb, depending on spectral integration times, and the signal was linear up to 5 ppm. Results for all control samples were in good agreement with the expected values. Twelve of the foods contained detectable titanium, ranging from 0.001 to 0.782% by weight, but only eight indicated this on their labels, four being exempt under food labelling regulations. Based on food portion sizes, an individual's daily intake of titanium dioxide could exceed 200 mg from just one of these products. This method may facilitate future studies on titanium dioxide intake, given the present limitations of food labelling. 相似文献
57.
Keen SP Cowden CJ Bishop BC Brands KM Davies AJ Dolling UH Lieberman DR Stewart GW 《The Journal of organic chemistry》2005,70(5):1771-1779
The development of a practical and highly convergent synthesis of an alpha(v)beta3 antagonist is described. The two key fragments present in this compound, a tetrahydropyrido[2,3-b]azepine ring system and a chiral 3-aryl-5-oxopentanoic acid, were constructed independently and then coupled at a late stage using a Wittig reaction. The pyridoazepine moiety was prepared from N-Boc 6-chloro-2-aminopyridine via directed ortho-metalation/alkylation followed by in situ cyclization. A Suzuki reaction was then used to attach the propionaldehyde side-chain required for Wittig coupling. The coupling partner was prepared from asymmetric methanolysis of a 3-substituted glutaric anhydride followed by elaboration of the acid moiety to the requisite beta-keto phosphorane. Using this route, kilogram quantities of the desired drug candidate were prepared. 相似文献
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X. -Q. Ding E. L. Bominaar E. Bill H. Winkler A. X. Trautwein S. Drüeke PH. Chaudhuri K. Wieghardt 《Hyperfine Interactions》1990,53(1-4):311-315
In this paper, we briefly summarize the main conclusions of the Mössbauer analysis of [L2Fe2(-OH)3] (ClO4)2·2CH3OH·2H2O with L=N,N',N"-trimethyl-1,4,7-triazacyclononane, a novel dimeric iron compound, which possesses a central exchange-coupled delocalized-valence Fe(II/III) unit. The complete delocalization of the excess electron in the dimeric iron center is concluded from the indistinguishability of the two iron sites in Mössbauer spectroscopy. The magnetic Mössbauer spectra imply a system spinS
t=9/2 for the dimer in its ground state. The values for hyperfine and spin-Hamiltonian parameters, obtained from simulations of the Mössbauer spectra, are =0.74 mms–1, E
Q=–2.14 mms–1,A
=–10.6 T,A
=–13.5 T andD=1.8 cm–1. The system spinS
t=9/2 is interpreted to be a consequence of double-exchange coupling. 相似文献
60.