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1.
Picking battles wisely: plant behaviour under competition 总被引:2,自引:0,他引:2
ARIEL NOVOPLANSKY 《Plant, cell & environment》2009,32(6):726-741
Plants are limited in their ability to choose their neighbours, but they are able to orchestrate a wide spectrum of rational competitive behaviours that increase their prospects to prevail under various ecological settings. Through the perception of neighbours, plants are able to anticipate probable competitive interactions and modify their competitive behaviours to maximize their long-term gains. Specifically, plants can minimize competitive encounters by avoiding their neighbours; maximize their competitive effects by aggressively confronting their neighbours; or tolerate the competitive effects of their neighbours. However, the adaptive values of these non-mutually exclusive options are expected to depend strongly on the plants' evolutionary background and to change dynamically according to their past development, and relative sizes and vigour. Additionally, the magnitude of competitive responsiveness is expected to be positively correlated with the reliability of the environmental information regarding the expected competitive interactions and the expected time left for further plastic modifications. Concurrent competition over external and internal resources and morphogenetic signals may enable some plants to increase their efficiency and external competitive performance by discriminately allocating limited resources to their more promising organs at the expense of failing or less successful organs. 相似文献
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一品红试管苗移栽驯化期叶片的解剖结构变化 总被引:3,自引:0,他引:3
对一品红试管苗移栽驯化,同时研究了驯化过程中叶片结构的变化,结果表明,一品红在珍珠岩基质中成活率达98%,随着移栽时间的延长,表皮细胞增大,排列紧密;叶肉细胞间隙减小,栅栏组织细胞长度增加,主脉增厚,导管数目增加,保水,输水和抗逆能力增强。 相似文献
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OBJECTIVE: To discover cancer patients'' views about disclosure of information to their family, their family''s influence over the information given them, and their preferences for doctors'' behaviour if they and their family disagree, as a complement to applied ethical theory. DESIGN: Semistructured interviews followed by qualitative content analysis. SETTING: Mainly urban British general practice. SUBJECTS: 30 patients in whom cancer, excluding basal and squamous cell skin carcinomas, was diagnosed 1-7 years earlier. RESULTS: All subjects wished doctors to respect their views rather than those of their family, should they differ. With their consent, subjects favoured close family receiving information about their illness, all but one mentioning advantage to their family. Without such consent, six unconditionally favoured disclosure of information to their family while seven unconditionally opposed disclosure. Seventeen participants restricted their approval for such disclosure to specific circumstances. Only two participants approved of their family influencing the information that they received about their illness; all but seven wished to receive full information, the exceptions relating to information about bad prognosis. CONCLUSIONS: Subjects favoured openness with their family but most rejected unconditional disclosure of information without their consent and their family influencing what information they would be given. They valued respect for their autonomy more highly than beneficence and considered that their own needs took priority over those of their family. 相似文献
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《Animal behaviour》1986,34(2):444-459
A ‘Monte Carlo’ method was developed for characterizing matrilines of rhesus monkey infants (Macaca mulatta) born to their mothers within six similar captive social groups, according to behavioural measures, and for characterizing social groups according to their matrilines' median scores. Eight- and 16-week-old infants differed according to their groups, but not according to their matrilines, in measures of their activity in the vicinity of their mothers, and the frequencies with which social companions other than the mother initiated social contacts with them while they were out of contact with their mothers. Sixteen-week-olds differed according to their groups in the frequencies with which their mothers rejected them, and 8-week-olds in the frequencies of the social contacts they initiated with companions other than mother while off their mothers. When tested with their mothers, in a mildly disturbing situation away from other social companions, 52-week-olds differed according to their group of origin in time spent out of contact with their mothers. Different groups were seen as producing infants differing in ‘enterprise’ from their eighth week, in the sense of being ready to initiate social contacts with others while off their mothers at 8 weeks, and of being off their mothers in the test at 52 weeks. Cases where the 8-week measures did not reflect infant enterprise could be explained in terms of other aspects of the relationships involving the infants and their mothers in the social group. In particular, matrilines differed consistently in dominance status, and some mothers also received high levels of aggression from other adults. Mothers receiving high levels of aggression were more responsible for maintaining proximity with their 8-week-old infants, and their 8-week-olds were less often involved in social contacts with others. 相似文献
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Function and structure of inherently disordered proteins 总被引:2,自引:0,他引:2
The application of bioinformatics methodologies to proteins inherently lacking 3D structure has brought increased attention to these macromolecules. Here topics concerning these proteins are discussed, including their prediction from amino acid sequence, their enrichment in eukaryotes compared to prokaryotes, their more rapid evolution compared to structured proteins, their organization into specific groups, their structural preferences, their half-lives in cells, their contributions to signaling diversity (via high contents of multiple-partner binding sites, post-translational modifications, and alternative splicing), their distinct functional repertoire compared to that of structured proteins, and their involvement in diseases. 相似文献
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《Ethnic and racial studies》2012,35(3):516-532
ABSTRACTWe critically review and discuss several methodological problems with their analysis. Their definition of the occupational hierarchy is unclear, and their inadequate statistical models exacerbate the vagueness of their results. They ignore gender interactions, and the age range of their target population seems too narrow for their research concerns. Their interpretation of their own statistical findings on occupational attainment is fundamentally flawed although they refuse to acknowledge it. Their reported results cannot be replicated based on the information that they are willing to reveal about their analysis which suggests additional, undisclosed errors. In our reanalysis of their data using more appropriate methods, we find that rather than being systematically disadvantaged, the occupational attainment of most second-generation Asian Americans has either achieved parity with whites or has exceeded them after controlling for age, educational level, and survey year. 相似文献
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The effects of partner togetherness on salivary testosterone in women in long distance relationships
Lisa Dawn Hamilton 《Hormones and behavior》2010,57(2):198-202
The present study examined whether women's testosterone levels are influenced by being with a sexual and romantic partner after a period of sexual abstinence. Women in long distance relationships (n = 15) provided five saliva samples: at least 1 week before seeing their partner (and at least 2 weeks since their last visit), the day before seeing their partner, when they were with their partner but prior to engaging in sexual activity, the day after their first sexual activity, and 3 days after they were separated from their partners. Salivary testosterone was lowest when participants had been away from their partners for at least 2 weeks and highest the day before they were to see their partners and the day after sexual activity. Results from this study indicated that women's testosterone increased both the day before they were with their partners and they day after they first engaged in sexual activity. However, something about initially reuniting with their partners returned their testosterone to baseline levels, which may be an effect of being in the same location as a partner, or just a state fluctuation due to nervousness or other psychological state. 相似文献
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Moshe Shokeid 《Ethnos》2013,78(2):219-238
Ethnographic texts preserve the historicity and losses of both the people observed and their observer. However, anthropologists rarely inform their readers about the circumstances of their departure from a fieldwork project. Without formally indicating the completion of their research goals, they usually move on to a new field and cease publishing on their former site. This procedure seemed natural enough when anthropologists conducted their studies in remote Third World locations. The constraints of distance, time, and budget made that abrupt separation seemingly inevitable and self-explanatory. But when anthropologists choose fieldwork sites that are close to home or easy to revisit, or conduct long-term research, their relationships with their subjects change radically, both during fieldwork and during the stages of writing and publishing the ethnographic text. Consequently, their eventual exit from the field involves a different process. Based on the experience of a fifteenyear engagement in the study of a gay synagogue in New York, this paper explores the latter process. The issue of exiting presents a methodological, emotional, and ethical problem meriting serious professional consideration. 相似文献
10.
The ability to perform predictive genetic testing of children raises ethical concerns regarding whether and when to test and the disclosure of results. Semi-structured interviews with a convenience sample of pediatricians (12) and geneticists (13) were conducted to see how they would react to parental requests for predictive genetic testing of their children, and their attitudes about testing their own children. We also asked about disclosure attitudes and practices for their patients' relatives and within their own families. Respondents would provide predictive genetic testing for most conditions, yet were less likely to seek this information about their own children. Respondents believed it was very important for patients to share some types of genetic information with relatives, and were directive in their counseling about intrafamilial disclosure, especially within their own families. Although respondents would almost never breach patient confidentiality, many would breach confidentiality within their own families. Health care professionals distinguish between their professional and personal roles with regard to issues of access and confidentiality in predictive testing of children. They are willing to provide greater access and more confidentiality for their patients than within their own families. 相似文献
11.
Jean-Etienne Bassard 《Phytochemistry》2010,71(16):1808-1824
Phenolamides constitute a diverse and quantitatively major group of secondary metabolites resulting from the conjugation of a phenolic moiety with polyamines or with deaminated aromatic aminoacids. This review summarizes their bioactivities and their reported roles in plant development, adaptation and defence compared to those of their polyamine precursors. The most conclusive recent developments point to their contribution to cell-wall reinforcement and to direct toxicity for predators and pathogens, either as built-in or inducible defence. Phenolamides were often considered as accumulated end-chain products. Recent data bring a light on their biosynthesis and suggests their possible contribution in the branching of the phenylpropanoid metabolism. 相似文献
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Johnson et al. (2013) found that morphometric measurements of dragonfly wings taken from actual specimens and measurements taken from whole-drawer images of those specimens were equally accurate. We do not believe that their conclusions are justified by their data and analysis. Our reasons are, first, that their study was constrained in ways that restrict the generalisability of their results, but second, and of far greater significance, their statistical approach was entirely unsuited to their data and their results misled them to erroneous conclusions. We offer an alternative analysis of their data as published. Our reanalysis demonstrates, contra Johnson et al., that measurements from scanned images are not a reliable substitute for direct measurement. 相似文献
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壳聚糖作为药物缓释控释载体的研究进展 总被引:4,自引:0,他引:4
壳聚糖因其具有良好的生物学特性而成为多种药物载体研究的热点。药物经过壳聚糖负载后,不仅能够达到缓释控释的目的,还能够改变药物的给药方式,以此减少给药次数,降低药物不良反应,提高药物生物利用度。本文就壳聚糖和改性壳聚糖作为普通药物和生物大分子药物载体的研究进展作一综述。 相似文献
15.
Vanesa Nahir?ak Natalia Inés Almasia Horacio Esteban Hopp Cecilia Vazquez-Rovere 《Plant signaling & behavior》2012,7(8):1004-1008
Snakin/GASA proteins are widely distributed among plant species. They are expressed in different plant organs with high tissue and temporal specificity, and their subcellular localization varies among the different members. Interestingly, all of them maintain 12 cysteines of the C-terminus in highly conserved positions of the aminoacid sequences that are essential for their biochemical activity and probably responsible for their protein structure. Despite their common features, their functions are not completely elucidated and little is known about their mode of action. This review focuses on the current knowledge about this intriguing family of peptides and advances comprising gene regulation analyses, expression pattern studies and phenotypic characterization of mutants and transgenic plants. Furthermore, we discuss the roles of Snakin/GASA proteins in several aspects of plant development, plant responses to biotic or abiotic stress and their participation in hormone crosstalk and redox homeostasis. 相似文献
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北京地区蕨类植物区系分析 总被引:10,自引:3,他引:10
对北京地区蕨类植物区系进行了初步分析,研究表明,北京共有蕨类植物77种,隶属于19科34属,以蹄盖蕨科、岩蕨科、鳞毛蕨科、卷柏科等为优势科,以岩蕨属、卷柏属、铁角蕨属等为优势属,科内及属内分化程度较低,种类组成贫乏;地理成分以温带成分占优势,有11属为温带分布属,占非世界分布属总数的61.11%,除世界种和中国特有种外,全为温带性质的种;生境特点以石生为主,大多数种类分布在北京西部和北部的山区;与河北的关系最为密切,其次为山西、内蒙、辽宁、山东,与秦岭也有一定的联系,与西藏的关系疏远。 相似文献
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This paper is the fourth of an annual series reviewing the research concerning the endogenous opiate peptides. This installment covers only work published during 1981 and attempts to provide a comprehensive, but not exhaustive, survey of the area. Previous papers in the series have dealt with research done before 1981. Topics concerning endogenous opiates reviewed here include a delineation of their receptors, their distribution, their precursors and degradation, behavioral effects resulting from their administration, their possible involvement in physiological responses, and their interactions with other peptides and hormones. Due to the burgeoning literature in this field, the comprehensive nature of this review in the future will be limited to considerations of behavioral phenomena related to the endogenous opiates. 相似文献
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Oxytocin (OT) has been shown to play an important role in social bonding in animals. However, it is unclear whether OT is related to inter-species social bonding. In this study, to examine the possibility that urinary OT concentrations of owners were increased by their “dog's gaze”, perhaps representing social attachment to their owners, we measured urinary OT concentrations of owners before and after interaction with their dogs. Dog owners interacted with their dogs as usual for 30 min (interaction experiment) or were instructed not to look at their dogs directly (control experiment). We observed the behaviors of owners and their dogs during the experiments, and measured OT concentrations by radioimmunoassay in urine samples from the owners collected just before and 20 min after interaction with their dogs. Using a cluster analysis, owners could be divided into two groups: one received a longer duration of gaze from their dogs and reported a higher degree of relationship with their dogs (LG); the other received a shorter duration of gaze and reported a lower degree of relationship (SG). Urinary OT was higher in LG than SG after usual interaction with their dogs, but not in the control experiment. In the interaction experiment, a high correlation was found in LG between the frequency of behavioral exchanges initiated by the dog's gaze and the increase in urinary OT. We conclude that interactions with dogs, especially those initiated by the dog's gaze, can increase the urinary OT concentrations of their owners as a manifestation of attachment behavior. 相似文献