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1.
A high-performance liquid chromatographic procedure is described for the quantitative determination of epinephrine, norepinephrine, and dopamine in human plasma. The method, which is based on adsorption of the catecholamines to alumina and, after liberation, separation on a microparticulate bonded strong cation-exchange resin and amperometric detection, has been optimized to give complete baseline separation of the substances of interest. Dihydroxybenzylamine, a nonendogenous catecholamine, is used as the internal standard. The detection limit is about 0.1 pmol for dopamine. Analysis of data obtained for norepinephrine and epinephrine from a total of 59 plasma samples showed a good correlation to the corresponding values obtained with a radioenzymatic method. Some results from normal and pathological conditions are compared. 相似文献
2.
Dr. Karin Mannerstedt Dr. Narendra Kumar Mishra Dr. Ebbe Engholm Dr. Morten Lundh Dr. Charlotte S. Madsen Dr. Philip J. Pedersen Dr. Priska Le-Huu Dr. Søren L. Pedersen Dr. Nina Buch-Månson Dr. Björn Borgström Dr. Thomas Brimert Dr. Lisbeth N. Fink Dr. Keld Fosgerau Prof. Niels Vrang Prof. Knud J. Jensen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(9):3166-3176
A glucose responsive insulin (GRI) that responds to changes in blood glucose concentrations has remained an elusive goal. Here we describe the development of glucose cleavable linkers based on hydrazone and thiazolidine structures. We developed linkers with low levels of spontaneous hydrolysis but increased level of hydrolysis with rising concentrations of glucose, which demonstrated their glucose responsiveness in vitro. Lipidated hydrazones and thiazolidines were conjugated to the LysB29 side-chain of HI by pH-controlled acylations providing GRIs with glucose responsiveness confirmed in vitro for thiazolidines. Clamp studies showed increased glucose infusion at hyperglycemic conditions for one GRI indicative of a true glucose response. The glucose responsive cleavable linker in these GRIs allow changes in glucose levels to drive the release of active insulin from a circulating depot. We have demonstrated an unprecedented, chemically responsive linker concept for biopharmaceuticals. 相似文献
3.
4.
Zusammenfassung -Ketophosphoniumsalze der allgemeinen Struktur
können mit Alkylnitriten zu Triphenylphosphinoxid und -Ketonitrilen RCOCN oxydiert werden. Ähnlich werden Alkylenphosphorane A umgesetzt: Für R1=H, R2=Alkyl entstehen Nitrile, während für R1=Alkyl, R2=Alkyl Ketoximäther gebildet werden.
Mitt.:E. Zbiral, Mh. Chem.96, 1967 (1965). 相似文献
-Ketophopshonium salts of the general structure can be oxidized by alkylnitrites to form triphenylphosphinoxid and -ketomitriles. Alkylenphosphoranes triphenylphosphinoxid and -ketonitriles. Alkylenphosphoranes (A) can be oxidized in the same manner. For R1=H, R2=alkyl the reaction product is nitrile whereas for R1=alkyl, R2-alkyl the products are ketoxime ethers.
Mitt.:E. Zbiral, Mh. Chem.96, 1967 (1965). 相似文献
5.
Jane McDougall Lisbeth Schaubroeck 《Journal of Mathematical Analysis and Applications》2008,340(1):721-738
A JS surface is a minimal graph over a polygonal domain that becomes infinite in magnitude at the domain boundary. Jenkins and Serrin characterized the existence of these minimal graphs in terms of the signs of the boundary values and the side-lengths of the polygon. For a convex polygon, there can be essentially only one JS surface, but a non-convex domain may admit several distinct JS surfaces. We consider two families of JS surfaces corresponding to different boundary values, namely JS0 and JS1, over domains in the form of regular stars. We give parameterizations for these surfaces as lifts of harmonic maps, and observe that all previously constructed JS surfaces have been of type JS0. We give an example of a JS1 surface that is a new complete embedded minimal surface generalizing Scherk's doubly periodic surface, and show also that the JS0 surface over a regular convex 2n-gon is the limit of JS1 surfaces over non-convex stars. Finally we consider the construction of other JS surfaces over stars that belong neither to JS0 nor to JS1. 相似文献
6.
Nils Carlsson Hanna Gustafsson Christian Thörn Lisbeth Olsson Krister Holmberg Björn Åkerman 《Advances in colloid and interface science》2014
Mesoporous materials as support for immobilized enzymes have been explored extensively during the last two decades, primarily not only for biocatalysis applications, but also for biosensing, biofuels and enzyme-controlled drug delivery. The activity of the immobilized enzymes inside the pores is often different compared to that of the free enzymes, and an important challenge is to understand how the immobilization affects the enzymes in order to design immobilization conditions that lead to optimal enzyme activity. This review summarizes methods that can be used to understand how material properties can be linked to changes in enzyme activity. Real-time monitoring of the immobilization process and techniques that demonstrate that the enzymes are located inside the pores is discussed by contrasting them to the common practice of indirectly measuring the depletion of the protein concentration or enzyme activity in the surrounding bulk phase. We propose that pore filling (pore volume fraction occupied by proteins) is the best standard for comparing the amount of immobilized enzymes at the molecular level, and present equations to calculate pore filling from the more commonly reported immobilized mass. Methods to detect changes in enzyme structure upon immobilization and to study the microenvironment inside the pores are discussed in detail. Combining the knowledge generated from these methodologies should aid in rationally designing biocatalyst based on enzymes immobilized in mesoporous materials. 相似文献
7.
Lisbeth Fajstrup 《K-Theory》1998,14(1):43-77
On algebraic K-theory of a finite-dimensional semisimple real algebra the involution induced by an antistructure is studied. After Bousfield–Kan completion at 2, a component of the homotopy fixed point set is homotopy-equivalent to the fixed point set. The fixed point set is calculated. 相似文献
8.
Ausra Peciulyte Juris Kiskis Per Tomas Larsson Lisbeth Olsson Annika Enejder 《Cellulose (London, England)》2016,23(3):1521-1536
Enzymatic hydrolysis of cellulose provides a renewable source of monosaccharides for production of variety of biochemicals and biopolymers. Unfortunately, the enzymatic hydrolysis of cellulose is often incomplete, and the reasons are not fully understood. We have monitored enzymatic hydrolysis in terms of molecular density, ordering and autofluorescence of cellulose structures in real time using simultaneous CARS, SHG and MPEF microscopy with the aim of contributing to the understanding and optimization of the enzymatic hydrolysis of cellulose. Three cellulose-rich substrates with different supramolecular structures, pulp fibre, acid-treated pulp fibre and Avicel, were studied at microscopic level. The microscopy studies revealed that before enzymatic hydrolysis Avicel had the greatest carbon-hydrogen density, while pulp fibre and acid-treated fibre had similar density. Monitoring of the substrates during enzymatic hydrolysis revealed the double exponential SHG decay for pulp fibre and acid-treated fibre indicating two phases of the process. Acid-treated fibre was hydrolysed most rapidly and the hydrolysis of pulp fibre was spatially non-uniform leading to fractioning of the particles, while the hydrolysis of Avicel was more than an order of magnitude slower than that of both fibres. 相似文献
9.
DL Thomsen T Kurtén S Jørgensen TJ Wallington SB Baggesen C Aalling HG Kjaergaard 《Physical chemistry chemical physics : PCCP》2012,14(37):12992-12999
The gas phase hydrogen abstraction reaction between OH and CY(2)XH, where X = H, F, OH, or NH(2) and Y = H, CH(3) or F, in the absence and presence of a single water molecule is investigated using both density function theory, B3LYP, and explicitly correlated coupled cluster theory, CCSD(T)-F12. We find that a single water molecule could have a catalytic effect at low temperatures possible in laboratory experiments, but does not seem to catalyze these reactions at 298 K, and will not play a role under relevant atmospheric conditions. 相似文献
10.
Franz J. Schmied Christian Teichert Lisbeth Kappel Ulrich Hirn Robert Schennach 《Cellulose (London, England)》2012,19(3):1013-1021
A method is presented which enables analysis of lignin precipitated on the surface of kraft pulp fibers. As experimental input,
high-resolution atomic force microscopy phase images of the fiber surfaces have been recorded in tapping mode. A digital image
analysis procedure—based on the watershed algorithm—is applied to distinguish between cellulose fibrils and the precipitated
lignin. In this way, size distributions for the diameter of lignin precipitates on pulp fiber surfaces can be obtained. In
an initial application of the method, three softwood kraft pulps were analyzed: a black liquor cook with a very high content
of precipitated lignin, a bleached pulp where nearly no precipitated lignin is visible and an unbleached industrial pulp.
The proposed method is suggested as an appropriate tool to investigate the kinetics of lignin precipitation and the structure
of lignin precipitates in pulping and bleaching. 相似文献