Search results for " ASTER"
showing 10 items of 60 documents
Zvaigžņotā Debess: 2008, Pavasaris
2008
Latvijas Zinātņu akadēmija, Latvijas Universitāte
Zvaigžņotā Debess: 2016, Vasara (232)
2016
Contents: “ZVAIGŽŅOTĀ DEBESS” FORTY YEARS AGO: A.Balklavs. New Studies and Conclusions on Nucleus of the Galaxy (abridged) ; U.Dzērvītis. Discussion on Planetary System of Barnard’s Star Continues (abridged) ; M.Eliāss. Meeting of Solar Radio Radiation Section (abridged) ; DEVELOPMENTS in SCIENCE: O.Dumbrājs. Neutrino Oscillations: from the Outset to the Nobel Prize ; R.Misa. Conversation with Andris Ambainis on Quantum Computing Science ; DISCOVERIES: F.Gahbauer. First Direct Detection of Gravitational Waves ; I.Pundure. ATLASGAL Survey of Milky Way Completed ; SPACE RESEARCH and EXPLORATION: J.Jaunbergs. The Story of Pluto’s Satellites ; K.Schwartz. Conducting Ice and Magnetic Field of Ur…
Cytotoxic activity of some natural and synthetic guaianolides
2005
Several natural guaianolides and synthetic derivatives of repin (1) were tested and found to be active against tumor cell replication. Repin (1) and both mono- and di-halohydrin analogues (2, 7-9, 11, 12) showed significant antitumor potency. A more effective compound (17) was obtained by esterificating repin with the paclitaxel side chain.
Volatile components of aerial parts of Centaurea nigrescens an C. stenolepis growing wild in the Balkans
2010
The volatile constituents of the aerial parts of Centaurea nigrescens Willd, collected in Romania and of two samples of C. stenolepis A. Kerner from Bulgaria and Romania were obtained by hydrodistillation and analyzed. The main components of C. stenolepis were caryophyllene oxide (6.9-15.6%), hexahydrofarnesyl acetone (6.5-4.4%), heptacosane (6.0-4.9%) and p-vinyl guiacol (4.3-5.0%). The main components of C. nigrescens were caryophyllene oxide (9.9%), β-eudesmol (9.5%), spathulenol (7.6%), heptacosane (6.1%) and p-vinyl guiacol (5.5%). The chemotaxonomic significance with respect to their co-location in Sections Lepteranthus and Nigrescentes, respectively, is discussed.
ASTEROID SEARCH RESULTS FOR DIGITIZED ASTROPLATES OF 1.2m TELESCOPE IN BALDONE
2019
The work on the mass search for asteroids on astroplate images and the determination of their coordi- nates was begun in 2016. The basis for current search was the processing results of digitized photographic plates and films obtained at the observatory in Baldone in 1967-1993. Observations with a single exposure in different spectral bands were carried out using the 1.2m Schmidt telescope in Baldone. We used all observations in the U Johnson's spec- tral band (on plates) and significant part of them in V band (on films). Photometric band U was realized by combining emulsion ORWO Zu1 (Zu2 or Zu21 or Kodak 103aO or IIaO) with UG1 filter. For films with A600 emulsion and filter ZS17 a photome…
LA VALORIZZAZIONE DELLA FLORA SPONTANEA ATTRAVERSO LO STUDIO DI NUOVI BIOPESTICIDI: ARTEMISIA ARBORESCENS L.
2012
Il termine “biopesticidi” identifica un vasto insieme di molecole, sintetizzate naturalmente da piante od altri organismi vegetali, in grado di manifestare un’attività biologica nei confronti di agenti fitopatogeni di diversa origine, quali virus, batteri, funghi, artropodi ed altri. Tale attività può spaziare dalla semplice repressione di un particolare stadio di sviluppo del patogeno (sporulazione, crescita vegetativa, riproduzione) fino alla induzione di reazioni e processi metabolici che ne determinano la morte. Negli ultimi anni sono stati proposti molti nuovi formulati con queste caratteristiche, la cui diffusione, pur se ancora contenuta, si presenta in continua espansione. Verso que…
Morfologia, cariologia e anatomia fogliare nel genere Dittrichia Greuter (Asteraceae)
2004
All five species of the genus Dittrichia were examined as regards their morphology, karyology and anatomy particularly referred to the leaf istology and micromorphology. Two different analytical keys were elaborated basing on morphological features and leaf anatomy and micromorphology characters.
BIOTECHNOLOGICAL APPROACHES TO THE GENETIC IMPROVEMENT OF CHRYSANTHEMUM CINERARIAEFOLIUM L.
2011
The interest in sustainable agriculture has increased the demand of plant-derived compounds which can be less toxic both to mammals and to the environment than the synthetic agrochemicals. Chrysanthemum cinerariaefolium L. (Asteraceae), commonly termed pyrethrum, is an economically important crop from highlands of tropical and subtropical regions of the world. It is grown for the extraction of pyrethrins, natural insect repellents of plant origin. Pyrethrins are a mixture of six compounds produced by esterification of two acids (chrysanthemic and pyrethric acid) with three mono-terpene-alcohols (pyrethrolone-5, jasmolone-3 and cinerolone-4). The principale source of pyrethrins are the dried…
BALDONE OBSERVATORY IN THE CIRCLES OF TIME
2019
1957 – The first laboratory building, known as the White House, was built near Baldone on the Riekstu hill, in the territory of the next Observatory. 01.01.1958 – The Astronomy Sector was separated from the Institute of Physics and commenced independent activi- ty as the Laboratory of Astrophysics at the Latvian Acade- my of Sciences (LAS). In 1967, with the decision of the Presidium of the Latvian SSR LAS the Laboratory of As- trophysics was transformed into the Radioastrophysic Ob- servatory at LAS. Under the leadership of the first director, Janis Ikaunieks, an instrumental observation base develops – a 1.2m Schmidt telescope was installed in 1966 for opti- cal observations. The project …
Chemical composition of the essential oil of Jacobaea maritima (L.) PelserMeijden and Jacobaea maritima subsp. bicolor (Willd.) B. Nord.Greuter (Aste…
2015
In this study, the chemical compositions of the essential oils from aerial parts (JmA) and radices (JmR) of Jacobaea maritima (L.) Pelser & Meijden, collected in Croatia, and of Jacobaea maritima subsp. bicolor (Willd.) B. Nord. & Greuter, collected in Sicily, were evaluated by using gas chromatography and gas chromatography–mass spectrometry. The main components of the essential oil from J. maritima, both in JmA and JmR, were pentacosane (15.7%), heptacosane (13.1%) and nonacosane (8.1%) whereas the essential oil from J. maritima subsp. bicolor was characterised by the presence of hexadecanoic acid (14.6%), caryophyllene oxide (9.3%) and hexahydrofarnesylacetone (6.5%). The comparison of t…