首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   29篇
  免费   0篇
  2019年   2篇
  2018年   1篇
  2017年   1篇
  2010年   1篇
  2007年   1篇
  2006年   1篇
  2003年   1篇
  2002年   2篇
  1995年   1篇
  1984年   2篇
  1983年   5篇
  1982年   2篇
  1981年   2篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1977年   2篇
  1973年   1篇
排序方式: 共有29条查询结果,搜索用时 15 毫秒
11.
Fifty-seven lichens were documented in Hooker's Supplement to the English Botany , published in five volumes from 1829 to 1866, when British lichenology was, until 1851, largely in a state of stagnation. These included 26 new lichens described by William Borrer, one of which, Verrucaria Hookeri (now Dacampia hookeri ), has proved to be a lichenicolous lichen. The merit of his work is discussed. One new species, namely Strigula Babingtonii , was described by the Reverend Miles Joseph Berkeley, but this is now regarded as a non-lichenized ascomycete fungus. An attempt was made to trace the whereabouts of all the type specimens, and only one could not be located. The current taxonomic status of the new species was investigated by the critical study of original references. No names require correction, but the authorities for Bacidia incompta (Borrer) Anzi and Verrucaria fuscella (Turner) Winch & Thornhill need emendation. The copyright dates of the plates are given, which should be accepted as those of publication.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 154 , 381–392.  相似文献   
12.
The transformation of testosterone into estradiol in the brain plays a key role in several behavioral and physiological processes, but it has been so far impossible to localize precisely the cells of the mammalian brain containing the relevant enzyme, viz., aromatase. We have recently established an immunohistochemical technique that allows the visualization of aromatase-immunoreactive cells in the quail brain. In this species, a marked increase in the optical density of aromatase-immunoreactive cells is observed in subjects that have been treated with the aromatase inhibitor, R76713 or racemic Vorozole. This increased immunoreactivity, associated with a total blockade of aromatase activity, has been used as a tool in the present study in which the distribution of aromatase-immunoreactive material has been reassessed in the brain of mice pretreated with R76713. As expected, the aromatase inhibitor increases the density of the immunoreactive signal in mice. Strongly immunoreactive cells are found in the lateral septal region, the bed nucleus of the stria terminalis, the central amygdala, and the dorso-lateral hypothalamus. A less dense signal is also present in the medial preoptic area, the nucleus accumbens, several hypothalamic nuclei (e.g., paraventricular and ventromedial nuclei), all divisions of the amygdala, and several regions of the cortex, especially the cortex piriformis. These data demonstrate that, contrary to previous claims, aromatase-immunoreactive cells are present in all brain regions that have been shown previously to contain high aromatase activity.  相似文献   
13.
Leukotriene D4 (5 μg/ml) aerosol constricts airways of dogs with nonspecific airway hyperreactivity but not of mongrel dogs which lack nonspecific airway hyperreactivity. RL increased 200 + 25% and Cdyn decreased to 77 ± 5% of the pre-challenge value. LTD4 (10 μg/ml) produced no further increase. Atropine (0.2 mg/kg) prevented the increase in RL and decrease in Cdyn, suggesting that part of the effect of LTD4 on airways is neurally mediated.  相似文献   
14.
A novel species of non-histone protein having a molecular weight of approximately 20,000 (20K), abundantly localized in the dorsolateral prostate, was found to be decreased in the content by castration and to be restored by replacement of androgen, in addition to non-histone proteins of molecular weights ≥ 34,000. The content of 20KDNA was more rapidly decreased by castration, but more slowly restored by replacement of androgen, with the dorsolateral prostate than the ventral prostate. Of other nuclear proteins, non-histone proteins of molecular weights ≥ 90,000 in the dorsolateral prostate were more susceptible to the decrease by castration, whereas those of all kinds of histones were hardly dependent on the androgen level.  相似文献   
15.
The appearance of plasma cells, specific for antigen or autologous idiotypic antibody, in rabbits immunized systemically, orally, or orally-systemically was determined using immunofluorescence techniques. Oral or parenteral immunizations alone did not lead to the appearance of anti-idiotypic cells in mucosal tissues, although IgA antigen-binding cells were observed in these sites after the oral administration of antigen. However, when rabbits were primed with orally administered antigen, followed by a regimen of concurrent oral—parenteral immunizations, IgG anti-idiotypic plasma cells were demonstrated in mucosal lymphoid tissues.  相似文献   
16.
Close membrane associations between the endoplasmic reticulum and the plasma membrane (ER-PM) occur in specialized regions of the rat Sertoli cell cytoplasm. They are characterized, in freeze fracture replicas, as mesa-like modifications of E membrane fracture faces or as corresponding discoid depressions on P membrane fracture faces. When these structures lie along transitional regions in the membrane fracture plane, they are seen to be complementary, and the space between them to be greatly reduced. These specialized close membrane associations may represent adhesive sites between the endoplasmic reticulum and the plasma membrane. However, their resemblance to vascular endothelial fenestrae which are known to be sites of increased membrane permeability may suggest other functional roles.  相似文献   
17.
Gap junctions between sertoli and germ cells of rat seminiferous tubules   总被引:2,自引:0,他引:2  
Ultrastructural observations of rat seminiferous tubules show clearly the presence of plasma membrane junctions between Sertoli and germ cells in the basal and adluminal compartments. Results obtained from the freeze fracture and thin section techniques were correlated in order to elucidate the nature of these intercellular junctions. We suggest that these intercellular membrane specializations are gap junctions which occur within regions of plasma membrane that also exhibit adherens-like modifications.  相似文献   
18.
Distinguishing the factors that influence activity within a species advances understanding of their behavior and ecology. Continuous observation in the marine environment is not feasible but biotelemetry devices provide an opportunity for detailed analysis of movements and activity patterns. This study investigated the detail that calibration of accelerometers measuring root mean square (RMS) acceleration with video footage can add to understanding the activity patterns of male and female Port Jackson sharks (Heterodontus portusjacksoni) in a captive environment. Linear regression was used to relate RMS acceleration output to time‐matched behavior captured on video to quantify diel activity patterns. To validate captive data, diel patterns from captive sharks were compared with diel movement data from free‐ranging sharks using passive acoustic tracking. The RMS acceleration data showed captive sharks exhibited nocturnal diel patterns peaking during the late evening before midnight and decreasing before sunrise. Correlation analysis revealed that captive animals displayed similar activity patterns to free‐ranging sharks. The timing of wild shark departures for migration in the late breeding season corresponded with elevated diel activity at night within the captive individuals, suggesting a form of migratory restlessness in captivity. By directly relating RMS acceleration output to activity level, we show that sex, time of day, and sex‐specific seasonal behavior all influenced activity levels. This study contributes to a growing body of evidence that RMS acceleration data are a promising method to determine activity patterns of cryptic marine animals and can provide more detailed information when validated in captivity.  相似文献   
19.
A rapid semi-quantitative ecological risk assessment method (productivity and susceptibility analysis) indicated that, despite its low biological productivity, the Port Jackson shark Heterodontus portusjacksoni is at low risk to all fishing methods in far-eastern Victoria, Australia, under the present fishing practices, because of its low catch susceptibility. The risk to this population, however, would increase if the shark gillnet fishery operating in the region were to retain the species as a by-product. Demographic analysis indicated that the species has medium intrinsic population growth rate and potential rebound in comparison with other chondrichthyan species, juveniles have higher elasticity than mature females and both juvenile and mature females have higher elasticities than hatchlings. Because of its low biological productivity and moderate resilience to the effects of fishing, cautious management measures will be necessary to ensure the sustainable use of H. portusjacksoni if its marketing increases in the future. Information on the dynamics of a population that is valuable to provide management advice can be obtained through demographic methods, but rapid assessment methods can also provide complementary information on the effects of fishing by considering the catch susceptibility of the population to each fishing method.  相似文献   
20.
Børge Diderichsen (Fig. 1) is the President of the European Federation of Biotechnology (EFB) and Vice President at Novo Nordisk (Denmark). After a master's degree in biochemistry, followed by a Ph.D. in microbiology, both from the University of Copenhagen, he joined Novo Industry as part of a small team of researchers who were to examine whether genetically modified organisms (GMOs) could be used in the production of insulin and industrial enzymes. Since then he has played an important role in Novo Nordisk's efforts to resolve many of the problems that arise in connection with the production of GMOs and was a pioneer in bringing some of the first industrial enzymes from GMOs onto the market. Diderichsen has many honorary titles and has served on a large number of boards and commissions. Most recently he was invited to join the Commissioner's Advisory Group for Life Sciences, Genomics and Biotechnology for Health corresponding to the 6th Framework Programme. For more than 20 years he has contributed to the public debate concerning genetic engineering and ethics, biotechnology and society, conditions for universities and public research among others. He has been a major force in reforming the EFB, of which he was elected president in January 2002.
Full-size image (6K)
Fig. 1. Børge Diderichsen.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号