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排序方式: 共有137条查询结果,搜索用时 15 毫秒
71.
Population Ecology - Adult populations of the sugi bark borer,Semanotus japonicus Lacordaire, which attacks the trunks of Japanese cedar and cypress, were studied in two cedar stands in 1981 and... 相似文献
72.
Defending Robert Rosen's claim that in every confrontation between physics and biology it is physics that has always had to give ground, it is shown that many of the most important advances in mathematics and physics over the last two centuries have followed from Schelling's demand for a new physics that could make the emergence of life intelligible. Consequently, while reductionism prevails in biology, many biophysicists are resolutely anti-reductionist. This history is used to identify and defend a fragmented but progressive tradition of anti-reductionist biomathematics. It is shown that the mathematico–physico–chemical morphology research program, the biosemiotics movement, and the relational biology of Rosen, although they have developed independently of each other, are built on and advance this anti-reductionist tradition of thought. It is suggested that understanding this history and its relationship to the broader history of post-Newtonian science could provide guidance for and justify both the integration of these strands and radically new work in post-reductionist biomathematics. 相似文献
73.
Claude Macquart‐Moulin Richard Kaïm‐Malka 《Marine and Freshwater Behaviour and Physiology》2013,45(3):151-164
L'Isopode profond Cirolana borealis présente en milieu expérimental un rythme circadien endogène net d'émergence du sédiment, de géonégativité, et d'activité natatoire. Le rythme a pu être enregistré durant plus de 60 jours consécutifs en obscurité constante. Il se manifeste chez les animaux conditionnés à un éclairement de surface (100 à 10‐5 μW.cm‐2), chez ceux conditionnés à éclairement très réduit (10‐4 à 10‐11 μW.cm‐2), et chez ceux prélevés à ‐ 400 m, et immédiatement expérimentés. La phase d'activité, de durée variable selon les individus, est centrée sur le crépuscule. La période et l'amplitude sont sujettes à de fortes variations individuelles. Généralement inférieure à 24 h chez les animaux conditionnés au laboratoire, la période est le plus souvent supérieure à 25 h chez les animaux provenant directement du milieu naturel. La synchronisation semble essentiellement assurée par les variations lumineuses nycthémérales: un éclairement de valeur diurne provoque une géopositivité permanente et, le plus souvent, un enfouissement au moins partiel des individus, même durant la phase d'activité. 相似文献
74.
目的:探讨蓝斑区(LC)去甲肾上腺素能神经元在orexin 促麻醉觉醒中作用。方法:应用异氟烷对成年SD 大鼠进行麻醉,15
分钟后,将SD 大鼠随机分为6 组,分别注射orexin-A/B (100pmol/0.3 滋L) 及其溶剂saline (0.3 滋L);orexin I 型受体拮抗剂
SB334867/ II型受体拮抗剂TCS-OX2-29(20 滋g/0.3 滋L及其溶剂DMSO(0.3 滋L),通过观察大鼠翻正反射的消失和恢复时间,研究
蓝斑区微注射orexin 及其拮抗剂对异氟烷麻醉的诱导和觉醒的影响。结果:蓝斑区(LC)微注射四种试剂或其溶剂均对SD 大鼠异
氟烷麻醉的诱导时间无明显影响;蓝斑区(LC)微注射orexin-A 能缩短SD 大鼠异氟烷麻醉觉醒时间(P<0.001),而微注射orexinI
型拮抗剂SB334867 能延长觉醒时间(P<0.001);orexin-B、orexin II型受体拮抗剂TCS-OX2-29 对大鼠异氟烷麻醉的觉醒无明显影
响。结论:蓝斑区(LC)的去甲肾上腺素能神经元介导了orexin 的促麻醉觉醒作用。 相似文献
75.
Jane Ching Svetlana A. Musheyev Dipabali Chowdhury Julie A. Kim Yoon Choi John J. Dennehy 《Evolution; international journal of organic evolution》2013,67(1):10-17
Migration between populations can be a major evolutionary force. However, some disagreement exists as to precisely how migration affects population adaptation. Some theories emphasize the inhibitory effects of gene flow between locally adapted populations, whereas others propose that migration can enhance adaptation. Migration has also been theorized to rescue sink populations from extinction. In our experiments, we serially passaged bacteriophage Φ6 host range mutants under sink conditions on a novel host while manipulating the source and number of migrants into these experimental populations. Migrants from two sources were used: mutant Φ6 phage able to infect a novel host (treatment) and wild‐type Φ6 phage unable to infect a novel host (control). We used quadratic regressions to determine the relationship between the number of migrants per passage and the absolute fitnesses of experimental populations following 30 passages. Our results showed that migration from a control population had no effect on absolute fitnesses of our serially passaged populations following 30 passages. By contrast, the relationship between migrants per passage and absolute fitnesses for populations receiving migrants able to infect the novel host was best described by an upwardly concave curve. These results suggest that intermediate levels of migration can have favorable impacts on evolutionary adaptation. 相似文献
76.
目的:统计全麻术后患者苏醒期躁动(EA)的发生率,并分析其影响因素。方法:本研究为回顾性研究,分析2021年5月~2021年6月期间我院收治的204例全麻手术患者的临床资料,采用躁动-镇静程度量表(RASS)评分评价患者术后是否发生EA,观察全麻术后患者EA发生率,并根据患者术后是否发生EA进行分组,采用logistic回归分析其影响因素。结果:204例患者中有47例发生EA,发生率为23.04%,纳为EA组,剩余的157例未发生EA,纳为非EA组。EA组、非EA组在性别、全麻方式、术前用药、苏醒时间方面对比差异无统计学意义(P>0.05)。EA组、非EA组在年龄、手术类型、手术时间、留置胃管/导尿管、麻醉时间、美国麻醉医师协会(ASA)分级、术后镇痛、术后疼痛方面对比差异有统计学意义(P<0.05)。logistic回归分析结果显示,年龄≥50岁、手术类型为妇科手术或泌尿外科手术、留置胃管/导尿管、ASA分级为Ⅱ级、术后疼痛是EA发生的危险因素,而术后镇痛是EA发生的保护因素(P<0.05)。结论:年龄、手术类型、留置胃管/导尿管、ASA分级、术后疼痛、术后镇痛是全麻术后患者EA发生的影响因素,临床需重点关注并给予相应防控措施。 相似文献
77.
Carlo Polidori Irene Giordani Pablo Mendiola Josep D. Asís José Tormos Jesús Selfa 《Comptes rendus biologies》2010,333(3):255-264
The position of the emerging point has rarely been investigated as a factor possibly affecting the future nest settlement behaviour in Hymenoptera, in particular within nest aggregations. We studied the emergence and dispersion patterns of the digger wasp Stizus continuus. Individuals emerged daily in clumped patterns, possibly revealing a certain synchrony of emergence from the same nests, and protandry appeared both at seasonal and daily level. Differences between the number of females that nested relatively close or far from their emergence holes (EH) were either significant or not, depending on the year, and observed dispersal distances from the natal nests did not differ from those obtained by random simulations. By contrast, females nested close to the nearest conspecific nest. Size did not affect the dispersion patterns. EH are thus not important cues for nest establishment, and conspecific nests are probably the key cue for nest-founding females. In addition, males did not prefer to establish territories close to their natal nest. 相似文献
78.
Grasslands worldwide have been invaded by woody species during the last200 years. Atmospheric CO2 enrichment may indirectly havefacilitatedinvasion by reducing soil water depletion by grasses. We used a two-stepcorrelative approach to test this hypothesis with the invasive and native shrubhoney mesquite (Prosopis glandulosa Torr. var.glandulosa). 1) Water content to 0.15 m depthwas measured in grassland exposed to a CO2 gradient from 200 to 550mol/mol to evaluate the prediction that CO2enrichment lessens soil water depletion by grasses. 2) Soil water content andemergence and survival of mesquite seedlings were measured in adjacentgrasslandplots from which grass roots were excluded to 0.15 m depth toreduce water depletion or that were irrigated to increase soil water levels.With these measurements, we tested the hypothesis that mesquite establishmentislimited by water.Excluding grass roots doubled emergence of mesquite and almost tripledthe fraction of emergent seedlings that survived for 12 weeks following thefirst of two plantings. Seedlings were taller, heavier, and had greater leafarea when grown without grass roots. Root exclusion did not measurably affectsoil water during the 3-week period of seedling emergence, but soilwatercontent over the 12 weeks that seedling survival was studied was higher inplotsfrom which grass roots were excluded and following an April than May planting.Survivorship of mesquite seedlings correlated positively with soil watercontent. Percentage survival of seedlings increased from 1.5% to15% and 28% at the soil water content measured in grasslandexposed to CO2 concentrations of 270 (preindustrial), 360 (current),and 550 mol/mol (future), respectively. We infer thatrecent and projected increases in atmospheric CO2 concentration maybe large enough to increase establishment of invading mesquite seedlings ingrasslands that are severely water-limited. 相似文献
79.
Prevailing water sources and/or regional climate are known to have an important influence on hydromorphology and chemistry of high alpine streams, affecting biology and phenology of aquatic insects considerably. Seven reaches in two different stream types (glacial and non-glacial) in the European Central Alps were investigated along a longitudinal gradient above the tree line to elucidate community structure and emergence patterns of aquatic insects. Aquatic insect emergence was dominated by chironomid taxa in both streams (95.0% in the glacial vs. 90.5% in the spring-fed stream). Emergence rate was much higher in the non-glacial stream, with Chironomidae 638.9 ind. m−2 d−1 and EPT (Ephemeroptera, Plecoptera, Trichoptera) 20.3 ind. m−2 d−1 (annual mean), compared to the glacial stream (Chironomidae 132 ind. m−2 d−1 and EPT 7.0 ind. m−2 d−1). Whereas, in the glacial stream a richer and more diverse species composition was found at lower elevations, emergence rate and emerging taxa numbers were higher at higher altitude in the non-glacial stream. Seasonal comparisons also showed a significant difference between the two streams. In the glacial stream maximum emergence was in April/May, whereas, in the non-glacial stream in July. A comparison with similar studies carried out in alpine streams showed that abundance and biomass of emerging insects were relatively low in the glacial stream. The continuous emergence throughout the summer is another example of insect life-cycle adaptation to the harsh environmental conditions in glacial streams: most likely, emergence during the warmer summer months, where the probability of experiencing favourable climate conditions on land is higher than for the rest of the year, was an evolutionary advantage for many glacial stream taxa. 相似文献
80.
Probably gypsophytes are the most interesting set of edaphic specialists of arid and semiarid climates. Despite they conform
a global biodiversity priority, there are almost no information about those adaptive traits that confer such a specialised
behaviour. Our broad hypothesis is that gypsophytes are “refuge-endemics” that are able to grow on gypsum soils due to their
ability to surpass extremely hard gypsum soil physical crust during emergence. With this in mind we have conducted an experimental
approach combining field and greenhouse assays. Seeds from two gypsophytes, genuine and widely distributed in the Iberian
Peninsula gypsophytes (Helianthemum squamatum and Lepidium subulatum) and one gypsovag (Teucrium capitatum), a generalist plant that can also grow on gypsum soils were used in our experiments. Two complementary experimental approaches
were conducted. The first involved a field experiment in which the presence or absence of the physical crust together with
the sowing date were manipulated and a greenhouse experiment in which the irrigation amount and the types of soil were controlled.
Variables of interest were the percentage of germination, growth and survival. In the field experiment we found a significant
decrease in the final germination of the gypsovag in the plots with intact crusts. On the other hand, H. squamatum is able to grow in the three tested soils, despite higher survival and growth on genuine gypsum soils. Our results confirm
the hypothesis that gypsum edaphic specialists base their behaviour to a great extent on the ability to surpass extremely
hard gypsum surface crusts, although this seems a marginal adaptive trait as shown by the capability to grow on a complete
array of soils and the negative effect of the crust along the earlier development life stages of gypsophytes. Furthermore,
a gypsovag such as Teucrium capitatum presents extreme difficulties to emerge on non-disturbed gypsum physical crusts but once surpassed its growth and survival
is not limited. 相似文献