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Now showing items 11-20 of 44
Guaianolides from Centaurea sinaica
(
Elsevier
, 1990 , Article & Report)
Three sesquiterpene lactones were isolated from the aerial parts of Centaurea sinaica: amberboin, chlorohyssopifolin A and sinaicin. The latter is reported for the first time.
Major sterol composition of some algae from Qatar
(
Elsevier Science Ltd.
, 1995 , Article)
Thirteen macroscopic algae belonging to the three main divisions Chlorophyceae, Rhodophyceae and Phaeophyceae from the coast of Qatar (Arabian Gulf) were investigated for their sterol composition by using GC-MS coupling ...
Guaianolides from Picris radicata
(
Elsevier Science Ltd.
, 1996 , Article)
The methylene chloride-methanol (1:1) extract of the aerial parts of Picris radicata Forssk afforded two new guaianolides. The structures were established from spectral data.
Solid-State Ac-Conductivity Analysis For The Long Debated Catalytic Activity Of The Boralite Sieve
(
Qatar University
, 1996 , Article)
The ac-phase dependent impedance, capacitance and dielectric loss of boralite are measured and correlated with those of a similar history HZSM-5 as a function of frequency (0.1-100 kHz) and temperature (373-638 K) at 0.8 ...
Possible evidence for the existence of a hairy layer at the surface of polymer latex particles
(
John Wiley & Sons, Ltd.
, 1998 , Article)
In this work, an attempt is made to verify the existence of a hairy layer at the surface of polymer latex particles, and determine its thickness under different conditions. Two systems have been studied. In one system, ...
Mercury pollution in doha (Qatar) coastal environment
(
Wiley Periodicals, Inc.
, 1994 , Article)
Surface water and sediment samples were collected from the Doha coastal area and analyzed for content of physico-chemical forms of mercury. Dissolved reactive Hg (2.9 ng L?1) represented 81.0% of the total dissolved Hg ...
Ac-conductivity analysis of the effects of partial dealumination and γ-irradiation on the electric features of HZSM-5
(
Elsevier
, 1996 , Article)
For illustrating such titled effects, analysis of the electric impedance, capacitance, and dielectric loss dependences on the frequency W (0.1–100 kHz) and temperature T (373–673 K) is correlated at 0.8 V for γ-irradiated ...
Evidence by ac-conductivity for the higher mobility of boron (over aluminium)-associated Brønsted sites in boron-modified HZSM-5
(
Elsevier
, 1996 , Article)
A correlation ac-conductivity analysis is performed at 102–105 Hz, 373–613 K and 0.8 V for characterizing the effect of increasing boron incorporation in HZSM-5 lattice on altered electric features in BZSM-5 samples of ...
Flavonoids from Centaurea sinaica
(1992 , Article)
Four Newly isolated flavonoids from Centaurea sinaica
Fatty acid composition of twelve algae from the Coastal Zones of Qatar
(
Kluwer Academic Publishers
, 1997 , Article)
Fatty acid composition of twelve algal species from two different classes were determined. Three Chlorophyta species(Axetabularia calyxulux, Cladophors sericoides and Dictyosphaeria cavernosa) and nine Phaephyta species ...