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排序方式: 共有1909条查询结果,搜索用时 281 毫秒
991.
In this study the phytosociological structures of Pinuspinea L. forests occuring in K. Mara province in theeastern-mediterranean region have been investigated. The vegetation of theresearch area has been studied according to the Braun-Blanquet (1932) methodanda Gastridio ventricosi-Pinetum pineaeassociation has been recognised. 相似文献
992.
E. StÖcker 《Cell and tissue research》1962,58(5):790-797
Zusammenfassung Die unter dem Einfluß von TAA vergrößerten Leberzell-Nukleolen der Ratte inkorporieren in wesentlichem Umfang H3-Phenylalanin, wobei die Einbaurate der markierten Aminosäure in direkter Abhängigkeit zur Größe des Kernkörperchens steht. Die Resultate erlauben somit den Schluß, daß einmal in der Nukleolarsubstanz eine Synthese höherer EW-Körper bzw. eine Neubildung von Ribonukleoproteiden erfolgt, und daß zum andern eine Korrelation zwischen der Größe des Nukleolus und seiner synthetischen Aktivität im Hinblick auf seine EW-Syntheserate existiert. Der Tatbestand, daß die nukleoläre SK-Dichte (SK-Zahl/2) in unserem Experiment schon bei sehr kurzen Versuchszeiten (5 min nach Injektion der markierten Aminosäure) im Mittel etwa gleich der karyoplasmatischen SK-Dichte, im Einzelfalle aber ganz wesentlich höher als die karyoplasmatische ist, spricht für unser Beobachtungsgut weitgehend gegen eine alleinige Migration markierten Materials aus dem Karyoplasma in den Nukleolus. Dementsprechend stellt der Nukleolus als Funktionseinheit betrachtet einen selbständigen EW-Syntheseort dar.Die Untersuchungen wurden im Institut für Medizinische Isotopenforschung der Universität Köln (Leiter: Prof. Dr. W. Maurer) durchgeführt. 相似文献
993.
Various studies indicate that the mycotoxin ochratoxin A (OTA) is a carcinogenic, genotoxic, teratogenic, immunotoxic, and nephrotoxic agent. In the present study, the activities of some enzymes in the serum and liver of rats with ochratoxicosis and the effects of melatonin on these enzymes were investigated. Rats were divided into three equal groups, each consisting of eight rats; control, OTA (289 microg/kg per day) and OTA + melatonin groups for this study. In the OTA treated group, the level of lipid peroxidation (LPO) and the activities of glutathione peroxidase (GSH-Px) were increased in the liver and serum in comparison with the control group. The activities of catalase (CAT) and superoxide dismutase (SOD) were significantly changed in the serum when compared with controls. Our results showed structural tissue damage in the liver in OTA-treated rats. Melatonin decreased the OTA-induced damage to support the antioxidant defense system and/or with free radical scavenger action. 相似文献
994.
Cetin M Ozkul Y Unal A Eser B Oztürk O Kutlubay R Er O Burakgazi H 《Cell biology and toxicology》2000,16(6):385-390
The effect of medroxyprogesterone acetate (MPA) on the mitotic activity of bone marrow and testis during chemotherapy was
investigated experimentally in an animal study. A total of 120 male Swiss albino mice were included in this study. Six groups
were formed, each consisting of 20 mice. Low-dose MPA (LD-MPA) (15 mg/kg), high-dose MPA (HD-MPA) (100 mg/kg), LD-MPA plus
cyclophosphamide (CP) (65 mg/kg), HD-MPA plus CP (65 mg/kg), and CP (65 mg/kg) were administered to the test groups and no
drug was administered to the control group. Bone marrow samples and testis were examined for mitotic activity rate (MAR) on
days 0, 18, 22, 26, and 30. In groups with regimens containing CP, MAR of hematopoietic cells in bone marrow was suppressed
significantly (p<0.05). There was no difference in MAR of hematopoietic cells in bone marrow between the groups given MPA or not (p>0.05). Mitotic activity rate of the testis cells was significantly suppressed in groups with regimens containing MPA (p<0.05). In conclusion, MPA inhibited mitotic activity of testis, but there was no effect on the mitotic activity of bone marrow.
These data do not seem to confirm the hypothesis of a myeloprotective effect of MPA.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
995.
Cadmium-induced changes in epithelial cells of the rat stomach 总被引:1,自引:0,他引:1
Asar M Kayişli UA Izgüt-Uysal VN Oner G Kaya M Polat S 《Biological trace element research》2000,77(1):65-81
The aim of this study was to determine the changes in the function and fine structure of the gastric mucosa following exposure
to high cadmium (Cd) for 30 d in rats. In the present study, control antimals were fed with normal food and tap water and
the remaining animals received Cd (15 ppm CdCl2) in drinking water for the same period. Receiving Cd for 30 d increased the mean blood (p<0.01) and mucosa (p<0.001) Cd levels, while decreased mucus thickness, mucin content (p<0.01) significantly. Basal acid output fell significantly (p<0.01). Light and electron microscopic examination revealed the following: (1) Cd decreases the mean number of surface mucous,
isthmic-neck, parietal cells (p<0.05) and chief cells (p<0.001) per unit from the control value and (2) in some cells of zymogenic unit, the Cd-induced alterations were characterized
with dilated Golgi cisternae, focal enlarged endoplasmic reticulum, broken tubulovesicles, degenerated mitochondria, dense
nuclei, as well as lysosomal structures. We concluded that Cd augments the elimination rate of zymogenic unit’s cells by increasing
the alteration rate, and the reduced basal acid output, mucin content, and mucus thickness can be explained easily with the
loss of zymogenic unit’s cell population. 相似文献
996.
Şule Eryiğit Ali Gelir Esranur Budak Caner Ünlü Azize Gömleksiz İbrahim Özçeşmeci Ahmet Gül 《Luminescence》2022,37(2):268-277
Quantum dots (QDs) are significant fluorescent materials for energy transfer studies with phthalocyanines (Pcs) and phthalocyanine (Pc)-like biomolecules (such as chlorophylls). Carbon-based QDs, especially, have been used in numerous studies concerning energy transfer with chlorophylls, but the numbers of studies concerning energy transfer between phthalocyanines and carbon-based QDs are limited. In this study, peripherally, hydroxythioethyl terminal group substituted metal-free phthalocyanine (H2Pc) and zinc phthalocyanine (ZnPc) were noncovalently (electrostatic and/or π–π interaction) attached to carbon QDs containing boron and nitrogen to form QD-Pc nanoconjugates. The QD-Pc conjugates were characterized using different spectroscopic techniques (Fourier transform infrared spectroscopy and transmission electron microscopy). The absorption and fluorescence properties of QD-Pc structures in solution were studied. It was found that the quantum yields of the QDs slightly decreased from 30% to 25% upon doping the QDs with heteroatoms B and N. Förster resonance energy transfer efficiency was calculated as 33% for BCN-QD/ZnPc. For the other conjugates, almost no energy transfer from QDs to Pc cores was observed. It was shown that the energy transfer between QDs to Pc cores was completely different from the energy transfer between QDs and photosynthetic pigments, and therefore we concluded that heteroatom doping in the QD structure and the existence of zinc metal in the phthalocyanine structure is obligatory for an efficient energy transfer. 相似文献
997.
Sleep and Biological Rhythms - This study aimed to determine the frequency of restless leg syndrome (RLS) and other sleep-related movement disorders and their effects on sleep quality in epilepsy... 相似文献
998.
999.
Microalgae harvesting via pH induced flocculation along with utilization of recovered medium after flocculation is one of the most economical methods for separating the microalgal biomass in order to reduce the dewatering cost. In this study, optimization of marine and freshwater microalgae flocculation by pH adjustment was investigated via central composite design methodology. One molar of KOH and NaOH solutions were used to increase the pH level of the microalgal culture. Increasing pH value of the medium provided the highest flocculation efficiency up to 92.63 and 86.18% with pH adjusted to 10.5 with KOH and NaOH solutions for marine microalgae Nannochloropsis oculata and freshwater microalgae Chlorella minutissima, respectively. Also, it was revealed that microalgae cells were still alive after flocculation process and their biochemical composition was not changed, and flocculated medium can be used again for the next microalgal production. According to the results, it can be said that this method is cheap and effective, simple to operate and provides the utilization of flocculated medium again. 相似文献
1000.