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Since the fragmentation of natural habitats is one of the most serious problems for many endangered species, it is highly interesting to study the properties of fragmented landscapes. As a basic property, landscape connectivity and its effects on various ecological processes are frequently in focus. First, we discuss the relevance of some graph properties(More)
Several taxonomic problems arise in the group of small, white European truffles, probably due to the over-emphasized significance of certain morphological features of ascomata. The distinction between Tuber rapaeodorum Tul. & C. Tul. and Tuber borchii Vittad. and Tuber puberulum Berk. & Broome has not been accepted in several recent studies. Furthermore,(More)
Maize (Zea mays L.) seedlings were pretreated with 0.001 g dm−3 S-methylmethionine (SMM) in the nutrient solution for 24 h and then subjected to chilling (6 °C for 2, 4, 6, 10, and 24 h). Cold stress significantly decreased the maximum quantum yield of photosystem II (variable to maximum chlorophyll fluorescence ratio, Fv/Fm) during the whole experiment but(More)
The aim of this study was to investigate the influence of three chlorhexidine species, chlorhexidine base and its salts (diacetate and digluconate), on the physico-chemical features of liquid crystalline systems and on drug transport through lipophilic membranes. Nonionic surfactant, Synperonic A7 (PEG(7)-C(13--15)) was selected for the preparation of the(More)
A sensitive, specific high-performance liquid chromatographic procedure was developed for the determination of plasma drotaverine levels. Basic plasma samples were adjusted to pH 1.5 and extracted with chloroform. HPLC [n-heptane-dichloromethane-diethylamine (50:25:2)] on a microporous silica column, with a variable-wavelength UV detector set at 302 nm(More)
Pelletization is increasingly applied currently for the preparation of solid oral controlled-release dosage forms. The production of the particles, which are regular in shape and size, can be achieved with the application of the proper polymer auxiliary materials and new pharmaceutical technological methods (extrusion, spheronization). Regularity in shape(More)
S-methylmethionine (SMM), an important intermediate compound in the sulphur metabolism, can be found in various quantities in majority of plants. The experiments were designed to determine the extent to which SMM is able to preserve cell membrane integrity or reduce the degree of membrane damage in the course of low-temperature stress. By measuring(More)
The paper gives an overview of literature on paraquat resistance of weeds and the proposed mechanism of resistance. New results we achieved on horseweed (Conyza canadensis /L./, Cronq.) are discussed in detail. It was demonstrated that there is no significant constitutive difference related to the paraquat resistance between untreated susceptible and(More)
Six new ecdysteroids have been isolated from SERRATULA TINCTORIA; these are: the 2,22- and 3,22-diacetates of 20-hydroxyecdysone, 5beta-hydroxyrubrosterone, 3-epi-poststerone, 3-epi-rubrosterone, and 22-oxo-20-hydroxyecdysone. These minor compounds were found together with the known ecdysteroids, 20-hydroxyecdysone, its 2-, 3-, and 22-monoacetates,(More)
Studying the metabolism of drotaverin (No-Spa¿), we have elaborated a method for the isolation, purification and separation of metabolites and of drotaverin excreted in unchanged form in the urine and feces. The structure of the chief metabolites was cleared by t.l.c., polarography, UV spectrophotometry, and mass spectrometry. It was stated that beside(More)