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排序方式: 共有620条查询结果,搜索用时 15 毫秒
611.
Summary The authors examined the karyotypes of the men 183 cm (6 ft.) tall or more among the 320 male residents of two Swedish institutions for the long-term care of epilepsy. All 14 men meeting this criterion proved to have the normal chromosome constitution-46, XY. 相似文献
612.
Olof Ryding 《Economic botany》1994,48(1):65-67
Artificial crossing experiments were made with three taxa of Ocimum. Plants ofO. forskolei Benth. andO. basilicum L. var. purpurascens Benth. were found to be interfertile, butO. americanum L. var.pilosum (Willd.) Paton was found to be reproductively isolated from the other two taxa. The new chromosome number 2n = 48 was counted inO. forskolei. These results suggest thatO. forskolei might be the closest relative of the Sweet Basil. The origin of the Sweet Basil is also discussed. 相似文献
613.
Effects of food availability on fledging condition and post-fledging survival in king penguin chicks 总被引:1,自引:0,他引:1
Olof Olsson 《Polar Biology》1997,18(3):161-165
Effects of summer food shortage on king penguin Aptenodytes patagonicus chicks were studied at South Georgia. Two cohorts were compared, fledging in the austral summers of 1992 (n = 32) and 1994 (n = 33) when availability of food was judged good and poor, respectively. The former cohort had a higher pre-fledging mean
mass (12.78 kg vs ≤ 10.03 kg), fledged earlier (median 5 January vs 21 January), and a higher proportion was re-sighted within
2 years of fledging (28% vs 0%). Within 4 years, 47% of the former cohort had been re-sighted (i.e. post-fledge survival);
in addition, one was observed at the Falkland Islands, and 22% had bred (i.e. recruitment) in their colony of origin. The
re-sighted chicks of the 1992 cohort fledged earlier than those not re-sighted (median 24 December vs 10 January), but it
remain unclear if they were heavier at fledging. All chicks in this study (n = 65) were marked with both transponders (subcutaneously implanted) and flipper bands (on one flipper), and no losses of
any markings were found (controlled up to 4 years afterwards). Therefore, data on chick post-fledging survival and recruitment
were not adjusted for losses of markings, as has been done in other studies.
Received: 21 October 1996 / Accepted: 2 February 1997 相似文献
614.
The effect of changed O2 - and CO2 -concentrations in air on oscillations in the transpiration rate of young oat plants in darkness has been investigated. Lowering the O2 -concentration to 5% did not affect the oscillations. When the CO2 in the air was removed, the transpiration rate increased, and the oscillations ceased. When the CO2 -concentration was raised to 0.3 or 3% the transpiration rate temporarily decreased, but the period of the oscillations was not changed. Further increase of the CO2 -concentration caused, after a temporary decrease, an increased transpiration rate, and the oscillations eventually ceased. The period of the oscillations was influenced by the temperature: a lower temperature gave a longer period. It is concluded that substomatal O2 -deficit or high CO2 -concentration do not play a crucial role in the origin of these oscillations. 相似文献
615.
Olof Ryding 《Nordic Journal of Botany》2009,27(4):257-265
Pericarp and seed structure was investigated in 13 out of the 16 species of the old Caryopteris s.l. and in a few species of the related Rubiteucris , Amethystea , Trichostema and Ajuga . The pericarp structure was found to be very variable, and the variation largely matches the most recent classification where Caryopteris s.l. is divided into six genera: Caryopteris s.s., Discretitheca , Pseudocaryopteris , Rubiteucris , Schnabelia and Tripora . All the six genera but Rubiteucris and Schnabelia can be distinguished from each other by differences in pericarp structure, and Caryopteris s.s. was found to have a particularly divergent structure. Similarities in pericarp structure also suggest that Schnabelia , Rubiteucris and Tripora may be closely related. 相似文献
616.
Donglin Jia Jingxuan Chen Siyu Zheng Dibya Phuyal Mei Yu Lei Tian Jianhua Liu Olof Karis Hkan Rensmo Erik M. J. Johansson Xiaoliang Zhang 《Liver Transplantation》2019,9(44)
Liquid‐state ligand exchange provides an efficient approach to passivate a quantum dot (QD) surface with small binding species and achieve a QD ink toward scalable QD solar cell (QDSC) production. Herein, experimental studies and theoretical simulations are combined to establish the physical principles of QD surface properties induced charge carrier recombination and collection in QDSCs. Ammonium iodide (AI) is used to thoroughly replace the native oleic acid ligand on the PbS QD surface forming a concentrated QD ink, which has high stability of more than 30 d. The ink can be directly applied for the preparation of a thick QD solid film using a single deposition step method and the QD solid film shows better characteristics compared with that of the film prepared with the traditional PbX2 (X = I or Br) post‐treated QD ink. Infrared light‐absorbing QDSC devices are fabricated using the PbS‐AI QD ink and the devices give a higher photovoltaic performance compared with the devices fabricated with the traditional PbS‐PbX2 QD ink. The improved photovoltaic performance in PbS‐AI‐based QDSC is attributed to diminished charge carrier recombination induced by the sub‐bandgap traps in QDs. A theoretical simulation is carried out to atomically link the relationship of QDSC device function with the QD surface properties. 相似文献
617.
Olof Joakim Pettersson Lars Aagaard Thomas Gryesten Jensen Christian Kroun Damgaard 《Nucleic acids research》2015,43(4):2433-2441
Myotonic dystrophy type 1 is caused by abnormal expansion of a CTG-trinucleotide repeat in the gene encoding Dystrophia Myotonica Protein Kinase (DMPK), which in turn leads to global deregulation of gene expression in affected individuals. The transcribed mRNA contains a massive CUG-expansion in the 3′ untranslated region (3′UTR) facilitating nucleation of several regulatory RNA-binding proteins, which are thus unable to perform their normal cellular function. These CUG-expanded mRNA–protein aggregates form distinct, primarily nuclear foci. In differentiated muscle cells, most of the CUG-expanded RNA remains in the nuclear compartment, while in dividing cells such as fibroblasts a considerable fraction of the mutant RNA reaches the cytoplasm, consistent with findings that both nuclear and cytoplasmic events are mis-regulated in DM1. Recent evidence suggests that the nuclear aggregates, or ribonuclear foci, are more dynamic than previously anticipated and regulated by several proteins, including RNA helicases. In this review, we focus on the homeostasis of DMPK mRNA foci and discuss how their dynamic regulation may affect disease-causing mechanisms in DM1. 相似文献
618.
Csaba Koncz William H. R. Langridge Olof Olsson Jeff Schell Aladar A. Szalay 《Genesis (New York, N.Y. : 2000)》1990,11(3):224-232
Genes encoding light-emitting luciferase were recently isolated from luminous marine bacteria and fireflies. Expression of luciferase genes in diverse organisms is a unique way for studying gene expression by simple and sensitive measurement of light. Recent advances in application of luciferase reporter genes are reviewed and documented by examples of in vivo visualization of their expression in transgenic plants. 相似文献
619.
The brain has been suggested to be especially sensitive to damage by reactive oxygen species. In this study, we examined the effects of hyperoxic conditions on the activities and mRNA levels of antioxidant enzymes in reaggregation cultures of rat forebrain cells. Cultures were exposed to 80% oxygen for 12–60 h starting on Days 17 and 33 in culture. Superoxide dismutase activities and mRNA levels were not affected by hyperoxia, whereas catalase activity was slightly decreased after 24 h in 80% oxygen at Day 17. Glutathione peroxidase activity was markedly decreased already after 12 h of hyperoxia, and decreased activities of glutathione reductase and glucose-6-phosphate dehydrogenase were also noted. The glutathione peroxidase mRNA levels were increased in hyperoxic cultures at Day 17 but not at Day 33. These results suggest that the enzymatic defense mechanisms against reactive oxygen species in the brain are rather weak and deteriorate during oxidative stress but that a potential for compensatory upregulation exists at least during the first postnatal weeks. 相似文献
620.
To develop and test a system for computer-assisted image analysis, repeated video recordings of reed canary-grass roots (Phalaris arundinacea L.) were made in an 18-window rhizotron. The images were digitized and processed using a Unix computer and the Khoros software development environment.Two image sizes, 126×95 mm and 61×46 mm, both comprising 650 × 490 pixels, were compared. Among image processing techniques used were median filtering, segmentation and skeletonization. Root area and length in both the topsoil and subsoil were estimated using the two image sizes. The resolution (image size) strongly affected the calculated root lengths. The results were compared with root length measurements obtained manually.Statistically significant differences in root length and area in the topsoil were detected between the sampling dates using the computer-assisted methods. Possible sources of error and methods for reducing them are discussed. 相似文献