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   57篇
  免费   4篇
  2021年   1篇
  2020年   2篇
  2018年   2篇
  2017年   2篇
  2016年   3篇
  2015年   6篇
  2014年   3篇
  2013年   4篇
  2012年   7篇
  2011年   4篇
  2008年   5篇
  2007年   2篇
  2006年   6篇
  2005年   1篇
  2004年   3篇
  2003年   1篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1979年   1篇
  1977年   1篇
  1976年   2篇
  1974年   1篇
排序方式: 共有61条查询结果,搜索用时 15 毫秒
1.
To conduct laboratory studies in unsedated animals that were similar anatomically and physiologically to man, five full term baboons (four Papio cynocephalus anubis, one Papio cynocephalus cynocephalus) were hand-reared. These infants were used as unsedated animal models in short-term lung clearance studies conducted from birth to 2 years of age. The hand-rearing techniques described here encouraged the formation of an infant-human rearer bond that permitted us to control the level of expressed aggressive behavior as the infant matured. These techniques resulted in baboons which displayed subordinate behavior, showed positive reception to human contact (without evidence of negative stereotypic behavioral anomalies) and remained cooperative subjects for our investigations of short-term pulmonary clearance. The baboons generally were above average in weight in comparison to conspecifically-reared baboons of similar age, sex and species. Representative lung retention curves presented on one baboon demonstrate the feasibility of lung clearance studies in these hand-reared animals. Due to its suitability for unsedated studies, this baboon model may be considered for other types of laboratory investigations.  相似文献   
2.
3.
BACKGROUND: Many types of differentiated eukaryotic cells display microtubule distributions consistent with nucleation from noncentrosomal intracellular microtubule organizing centers (MTOCs), although such structures remain poorly characterized. In fission yeast, two types of MTOCs exist in addition to the spindle pole body, the yeast centrosome equivalent. These are the equatorial MTOC, which nucleates microtubules from the cell division site at the end of mitosis, and interphase MTOCs, which nucleate microtubules from multiple sites near the cell nucleus during interphase. RESULTS: From an insertional mutagenesis screen we identified a novel gene, mod20+, which is required for microtubule nucleation from non-spindle pole body MTOCs in fission yeast. Mod20p is not required for intranuclear mitotic spindle assembly, although it is required for cytoplasmic astral microtubule growth during mitosis. Mod20p localizes to MTOCs throughout the cell cycle and is also dynamically distributed along microtubules themselves. We find that mod20p is required for the localization of components of the gamma-tubulin complex to non-spindle pole body MTOCs and physically interacts with the gamma-tubulin complex in vivo. Database searches reveal a family of eukaryotic proteins distantly related to mod20p; these are found in organisms ranging from fungi to mammals and include Drosophila centrosomin. CONCLUSIONS: Mod20p appears to act by recruiting components of the gamma-tubulin complex to non-spindle pole body MTOCs. The identification of mod20p-related proteins in higher eukaryotes suggests that this may represent a general mechanism for the organization of noncentrosomal MTOCs in eukaryotic cells.  相似文献   
4.
Individuals learn which of their actions are likely to be rewarded through trial and error. This form of learning is critical for adapting to new situations, which adolescents frequently encounter. Adolescents are also greatly influenced by their peers. The current study tested the extent to which adolescents rely on peer advice to guide their actions. Adolescent and young adult participants completed a probabilistic learning task in which they chose between four pairs of stimuli with different reinforcement probabilities, with one stimulus in each pair more frequently rewarded. Participants received advice about two of these pairs, once from a similarly aged peer and once from an older adult. Crucially, this advice was inaccurate, enabling the dissociation between experience-based and instruction-based learning. Adolescents and adults learned equally well from experience and no age group difference was evident in the overall influence of advice on choices. Surprisingly, when considering the source of advice, there was no evident influence of peer advice on adolescent choices. However, both adolescents and adults were biased toward choosing the stimulus recommended by the older adult. Contrary to conventional wisdom, these data suggest that adolescents may prioritize the advice of older adults over that of peers in certain decision-making contexts.  相似文献   
5.
Joubert syndrome (JBTS) is a recessive ciliopathy in which a subset of affected individuals also have the skeletal dysplasia Jeune asphyxiating thoracic dystrophy (JATD). Here, we have identified biallelic truncating CSPP1 (centrosome and spindle pole associated protein 1) mutations in 19 JBTS-affected individuals, four of whom also have features of JATD. CSPP1 mutations explain ∼5% of JBTS in our cohort, and despite truncating mutations in all affected individuals, the range of phenotypic severity is broad. Morpholino knockdown of cspp1 in zebrafish caused phenotypes reported in other zebrafish models of JBTS (curved body shape, pronephric cysts, and cerebellar abnormalities) and reduced ciliary localization of Arl13b, further supporting loss of CSPP1 function as a cause of JBTS. Fibroblasts from affected individuals with CSPP1 mutations showed reduced numbers of primary cilia and/or short primary cilia, as well as reduced axonemal localization of ciliary proteins ARL13B and adenylyl cyclase III. In summary, CSPP1 mutations are a major cause of the Joubert-Jeune phenotype in humans; however, the mechanism by which these mutations lead to both JBTS and JATD remains unknown.  相似文献   
6.
The central arbiter of cell fate in response to DNA damage is p53, which regulates the expression of genes involved in cell cycle arrest, survival and apoptosis. Although many responses initiated by DNA damage have been characterized, the role of actin cytoskeleton regulators is largely unknown. We now show that RhoC and LIM kinase 2 (LIMK2) are direct p53 target genes induced by genotoxic agents. Although RhoC and LIMK2 have well-established roles in actin cytoskeleton regulation, our results indicate that activation of LIMK2 also has a pro-survival function following DNA damage. LIMK inhibition by siRNA-mediated knockdown or selective pharmacological blockade sensitized cells to radio- or chemotherapy, such that treatments that were sub-lethal when administered singly resulted in cell death when combined with LIMK inhibition. Our findings suggest that combining LIMK inhibitors with genotoxic therapies could be more efficacious than single-agent administration, and highlight a novel connection between actin cytoskeleton regulators and DNA damage-induced cell survival mechanisms.  相似文献   
7.
We studied the reaction between vinyl butyrate and 2-phenyl-1-propanol in acetonitrile catalyzed by Fusarium solani pisi cutinase immobilized on zeolites NaA and NaY and on Accurel PA-6. The choice of 2-phenyl-1-propanol was based on modeling studies that suggested moderate cutinase enantioselectivity towards this substrate. With all the supports, initial rates of transesterification were higher at a water activity (a(w)) of 0.2 than at a(w) = 0.7, and the reverse was true for initial rates of hydrolysis. By providing acid-base control in the medium through the use of solid-state buffers that control the parameter pH-pNa, which we monitored using an organo-soluble chromoionophoric indicator, we were able, in some cases, to completely eliminate dissolved butyric acid. However, none of the buffers used were able to improve the rates of transesterification relative to the blanks (no added buffer) when the enzyme was immobilized at an optimum pH of 8.5. When the enzyme was immobilized at pH 5 and exhibited only marginal activity, however, even a relatively acidic buffer with a pK(a) of 4.3 was able to restore catalytic activity to about 20% of that displayed for a pH of immobilization of 8.5, at otherwise identical conditions. As a(w) was increased from 0.2 to 0.7, rates of transesterification first increased slightly and then decreased. Rates of hydrolysis showed a steady increase in that a(w) range, and so did total initial reaction rates. The presence or absence of the buffers did not impact on the competition between transesterification and hydrolysis, regardless of whether the butyric acid formed remained as such in the reaction medium or was eliminated from the microenvironment of the enzyme through conversion into an insoluble salt. Cutinase enantioselectivity towards 2-phenyl-1-propanol was indeed low and was not affected by differences in immobilization support, enzyme protonation state, or a(w).  相似文献   
8.
This paper investigates the commonalities in ethnoveterinary medicine used for horses between Trinidad (West Indies) and British Columbia (Canada). These research areas are part of a common market in pharmaceuticals and are both involved in the North American racing circuit. There has been very little research conducted on medicinal plants used for horses although their use is widespread. The data on ethnoveterinary medicines used for horses was obtained through key informant interviews with horse owners, trainers, breeders, jockeys, grooms and animal care specialists in two research areas: Trinidad and British Columbia (BC). A participatory validation workshop was held in BC. An extensive literature review and botanical identification of the plants was also done. In all, 20 plants were found to be used in treating racehorses in Trinidad and 97 in BC. Of these the most-evidently effective plants 19 of the plants used in Trinidad and 66 of those used in BC are described and evaluated in this paper. Aloe vera, Curcuma longaand Ricinus communisare used in both research areas. More research is needed in Trinidad to identify plants that respondents claimed were used in the past. Far more studies have been conducted on the temperate and Chinese medicinal plants used in BC and therefore these ethnoveterinary remedies reflect stronger evidence of efficacy.  相似文献   
9.

Background

Avoidance of allergens is still recommended as the first and best way to prevent allergic illnesses and their comorbid diseases. Despite a variety of attempts there has been very limited success in the area of environmental control of allergic disease. Our objective was to identify a non-invasive, non-pharmacological method to reduce indoor allergen loads in atopic persons' homes and public environments. We employed a novel in vivo approach to examine the possibility of using aluminum sulfate to control environmental allergens.

Methods

Fifty skin test reactive patients were simultaneously skin tested with conventional test materials and the actions of the protein/glycoprotein modifier, aluminum sulfate. Common allergens, dog, cat, dust mite, Alternaria, and cockroach were used in the study.

Results

Skin test reactivity was significantly reduced by the modifier aluminum sulfate. Our studies demonstrate that the effects of histamine were not affected by the presence of aluminum sulfate. In fact, skin test reactivity was reduced independent of whether aluminum sulfate was present in the allergen test material or removed prior to testing, indicating that the allergens had in some way been inactivated.

Conclusion

Aluminum sulfate was found to reduce the in vivo allergic reaction cascade induced by skin testing with common allergens. The exact mechanism is not clear but appears to involve the alteration of IgE-binding epitopes on the allergen. Our results indicate that it may be possible to diminish the allergenicity of an environment by application of the active agent aluminum sulfate, thus producing environmental control without complete removal of the allergen.  相似文献   
10.
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