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1.
麻竹不同造林方式对当年新竹生长的影响   总被引:2,自引:0,他引:2  
994~1996年在福建南靖县进行麻竹(DendrocalamuslatiflorusMunro)扦插苗造林和移栽母竹造林试验,扦插苗造林发笋数比移栽母竹造林发笋数多025个/丛,新竹直径大121cm。扦插苗造林后,当年萌动新竹越多,新竹直径呈增大的趋势,随着新竹萌发的先后顺序,扦插苗造林的新竹平均直径也有相应增大的趋势。移栽母竹造林当年,新竹的大小受新竹数和母竹直径的影响显著,新竹直径与母竹直径呈正相关,新竹越多,新竹直径呈减小的趋势,其新竹平均直径随萌发先后也呈依次减小的趋势。  相似文献   

2.
The behavioural response of the brown spiny mouse, Mus platythrix Bennett to new place and new object was studied in a plus (+) maze. The new place reaction was observed by allowing the mice to access an area which had previously been not exposed to them and the new object reaction was studied by introducing a change at the feeding point. The experiment suggested new place philia and new object philia in this species.  相似文献   

3.
2016 年5 月,美国、欧盟和日本共批准32 个新药,包括新分子实体、新有效成分、新生物制品、新增适应证及新剂型药物。 对全球首次获得批准的新分子实体、新有效成分、新生物制品进行分析,重点介绍这些药物的临床研究结果和研发历史进程。  相似文献   

4.
It is shown that in a diploid population at a genetic equilibrium with an uneven sex ratio the distribution of all (inertial) autosomal genes is symmetric between the two sexes. If several allelic genes occur in the population then the sex ratios of the various genotypes uniquely determine the uneven population sex ratio. The equilibrium is unstable to invasion by new genes which are relatively more frequent among the less numerous sex. A new proof is given to the fact that if genotype sex ratios do not change then, following an invasion by a new allele, a new stable polymorphic equilibrium can only correspond to a sex ratio which is more even than the old one. Application of these general results to a model of offspring sex determination by parents' autosomal genes shows the equilibrium to be unstable to invasion by new genes which tend to increase the production of offspring of the minority sex, as proposed by Fisher. The relevance of the Shaw-Mohler formula in this context is shown to derive from its role in describing the dynamics of autosomal genes in general. In connection with a model for offspring sex determination by one parent, a new proof is given to the fact that, following an invasion by a new allele, a new stable polymorphic equilibrium can only correspond to a sex ratio which is more even than the old one.  相似文献   

5.
Three new genera and three new species of Baetidae (Insecta: Ephemeroptera) are described from the Andes and Patagonia. Larvae of Andesiops, new genus, are distinguished by the apically bifid right prostheca and two rows of denticles on the tarsal claws. Larvae of Deceptiviosa, new genus, are distinguished by the apically bifid right prostheca and small subapical denticle on the tarsal claws. Larvae of Nanomis, new genus, are distinguished by the apically acute maxillary palp segment 2, smooth posterior margin of the terga, and paddle-shaped subapical seta on the hindtibiae. Adults of Andesiops and Deceptiviosa are similar, but distinguished from other South American baetids by having hindwings with a small costal process in the basal one third and three lon gitudinal veins with the middle vein being forked, and an elongate and ellipsoidal genital forceps segment 3. Larvae and adults of Andesiops peruvianus, new combination, are redescribed, and additional locale data are provided for Argentina, Bolivia, Ecuador, and Venezuela. Deceptiviosa ardua, new species, is described from larvae from Chile, and D. torrens, new species, is described from larvae and adults from Chile and Argentina. Nanomis galera, new species, is described from larvae from Argentina, Colombia, Ecuador, and Peru.  相似文献   

6.
A higher category is the result of a population's breaking-throuh into a new adaptive zone (attaining a new grade), and the subsequent adaptive radiation tiere. The taxonomic level of the new group is determined by the amount (quantitative and ualitative) of radiation that occurs; and tgis amount in turn is determined by the number of open sub-zones in the new zone and by the genetic plasticity of the new population. The more the new adaptive zone differs from the old one, the less likely a new population can survive in it. Should such survival occur, however, adaptations of the new population to the new zone will appear quickly. The new population will rapidly become quite different from the old one, minimizing the likelihood of finding intermediate forms, i. e., “missing links.” In addition, the intermediate population – the early entrants into the new zone – will be less well adapted to it than their descendents, and will become extinct. The combination of rapid extinction and an ephemeral transitional population explains the apparent gaps between higher-category taxa. These ideas do not help in solving such dilemmas of taxonomists as equivalence of taxa in different groups, and the taxonomic level at which to place a given group of species. But a higher taxonomic category itself is the result of a very real biological phenomenon, and that fact must influence systematicists.  相似文献   

7.
For the law, neuroscience changes nothing and everything   总被引:7,自引:0,他引:7  
The rapidly growing field of cognitive neuroscience holds the promise of explaining the operations of the mind in terms of the physical operations of the brain. Some suggest that our emerging understanding of the physical causes of human (mis)behaviour will have a transformative effect on the law. Others argue that new neuroscience will provide only new details and that existing legal doctrine can accommodate whatever new information neuroscience will provide. We argue that neuroscience will probably have a transformative effect on the law, despite the fact that existing legal doctrine can, in principle, accommodate whatever neuroscience will tell us. New neuroscience will change the law, not by undermining its current assumptions, but by transforming people's moral intuitions about free will and responsibility. This change in moral outlook will result not from the discovery of crucial new facts or clever new arguments, but from a new appreciation of old arguments, bolstered by vivid new illustrations provided by cognitive neuroscience. We foresee, and recommend, a shift away from punishment aimed at retribution in favour of a more progressive, consequentialist approach to the criminal law.  相似文献   

8.
On prediction of genetic values in marker-assisted selection.   总被引:13,自引:0,他引:13  
C Lange  J C Whittaker 《Genetics》2001,159(3):1375-1381
We suggest a new approximation for the prediction of genetic values in marker-assisted selection. The new approximation is compared to the standard approach. It is shown that the new approach will often provide substantially better prediction of genetic values; furthermore the new approximation avoids some of the known statistical problems of the standard approach. The advantages of the new approach are illustrated by a simulation study in which the new approximation outperforms both the standard approach and phenotypic selection.  相似文献   

9.
本文报道了黑蛋巢菌属Cyathus的三个新种、一个新变种和一个新记录种,它们分别是:四川黑蛋巢菌C.sichuanensis Liu et Y.M.Li,关帝山黑蛋巢菌C.guandishanensisLiu et Y.M.Li,云南黑蛋巢菌C.yunnanensis Liu et Y.M.Li,五台山黑蛋巢菌垣曲变种C.wutaishanensis Liu,Shangguan et Yuan var.yuanquensis Liu et Y.M.Li和栗褐黑蛋巢菌C.badius Kobayasi。模式标本除C.yunanensis Liu et Y.M.Li保存在中国科学院微生物研究所标本室外,其余均保存在山西大学真菌标本室。  相似文献   

10.
本文报道了黑蛋巢菌属Cyathus的三个新种、一个新变种和一个新记录种,它们分别是:四川黑蛋巢菌C.sichuanensis Liu et Y.M.Li,关帝山黑蛋巢菌C.guandishanensisLiu et Y.M.Li,云南黑蛋巢菌C.yunnanensis Liu et Y.M.Li,五台山黑蛋巢菌垣曲变种C.wutaishanensis Liu,Shangguan et Yuan var.yuanquensis Liu et Y.M.Li和栗褐黑蛋巢菌C.badius Kobayasi。模式标本除C.yunanensis Liu et Y.M.Li保存在中国科学院微生物研究所标本室外,其余均保存在山西大学真菌标本室。  相似文献   

11.
A new gene for a new purpose may be created by mutation of a pre-existing gene. But if that original gene is still required for its original purpose, and is to be retained side by side with the new, a spare copy is needed initially as raw material for the innovation. Thus in haploids the original gene must be duplicated before it is modified. But in diploids a spare copy of every gene is always available, and a mutant allele serving a new purpose can be easily established and maintained by heterosis in parallel with the old allele. Subsequent gene duplication will lead, via crossing-over, to insertion of the new gene in tandem with the old, as a permanent addition to the genome. Calculations show that diploids can thus enlarge their genomes with new genes for new purposes much more readily than haploids; in particular, they can more easily evolve the complex gene control systems characteristic of differentiated multicellular organisms. Sexual reproduction preserves diploidy, and so can be seen as the basis of these richer possibilities for evolutionary innovation.  相似文献   

12.
A new method for sampling meat surfaces was developed. Bacterial counts of beef carcasses by the cotton swab technique and by the new method showed that the latter gave higher counts. These counts were closely correlated with data obtained by using the swab method. Advantages of the new method are its simplicity, rapidity, and adaptability to routine use on any type of carcass.  相似文献   

13.
糖尿病是一种以高血糖为特征的慢性代谢性疾病,随着生活水平的提高,其发病率逐年上升,已成为危害人类健康的重要因素之 一。对于糖尿病的治疗药物研究,也从对传统机制的药物研究过渡到对具有新靶点和新作用机制的药物研究。其中基于这些新靶点设计 的新型非胰岛素类糖尿病治疗药物已进入临床研究阶段或已上市,给糖尿病的治疗带来了新的思路。按作用靶点和机制分类对较有开发 前景的非胰岛素类糖尿病治疗新药的研究进展进行综述。  相似文献   

14.
Over the years, agriculture across the world has been compromised by a succession of devastating epidemics caused by new viruses that spilled over from reservoir species or by new variants of classic viruses that acquired new virulence factors or changed their epidemiological patterns. Viral emergence is usually associated with ecological change or with agronomical practices bringing together reservoirs and crop species. The complete picture is, however, much more complex, and results from an evolutionary process in which the main players are ecological factors, viruses' genetic plasticity, and host factors required for virus replication, all mixed with a good measure of stochasticity. The present review puts emergence of plant RNA viruses into the framework of evolutionary genetics, stressing that viral emergence begins with a stochastic process that involves the transmission of a preexisting viral strain into a new host species, followed by adaptation to the new host.  相似文献   

15.
Three new species of Monocotyle were found on the gills of the coachwhip stingray, Himantura uarnak (Rajiformes: Dasyatidae) collected at Heron Island, Great Barrier Reef, Australia (23 degrees 27' S, 151 degrees 55 'E). Monocotyle helicophallus new species, Monocotyle multiparous new species and Monocotyle spiremae new species all have a single testis and are distinguished from other described Monocotyle species by size of body and hamulus and number of coils of the sclerotized male copulatory organ (21-22, three to four and 29-42, respectively). Monocotyle helicophallus new species is characterized by several muscular genital papillae, one of which is traversed by the ejaculatory duct; M. spiremae new species is distinguished by a sclerotized accessory structure associated with the distal end of the male copulatory organ, a vaginal sclerite and a conspicuous spherical, ejaculatory bulb; M. multiparous new species is distinguished by a large number of retained, thin-shelled eggs, many of which contain a fully developed oncomiracidium. A phylogenetic analysis of the 14 described species of Monocotyle utilizing 13 characters (11 binary and two multistate) produced the most parsimonious cladogram involving 18 steps with a consistency index of 0.78, two homoplasies and four unresolved polychotomies. Emended diagnoses of the Monocotylinae and Monocotyle are provided.  相似文献   

16.
分子生物学与进化的新理论   总被引:6,自引:0,他引:6  
孙毅  张伟 《生物学杂志》2004,21(5):16-18
论述了由于分子生物学取得的成就,而形成的生物进化的新理论,并阐述了若干新理论指导生产实践取得的巨大应用成果。  相似文献   

17.
Running increases the formation of new neurons in the adult rodent hippocampus. However, the function of new neurons generated from running is currently unknown. One hypothesis is that new neurons from running contribute to enhanced cognitive function by increasing plasticity in the adult hippocampus. An alternative hypothesis is that new neurons generated from running incorporate into experience-specific hippocampal networks that only become active during running. The purpose of this experiment was to determine if new neurons generated from running are selectively activated by running, or can become recruited into granule cell activity occurring during performance on other behavioral tasks that engage the hippocampus. Therefore, the activation of new 5-6 week neurons was detected using BrdU, NeuN, and Zif268 triple-label immunohistochemistry in cohorts of female running and sedentary adult C57BL/6J mice following participation in one of three different tasks: the Morris water maze, novel environment exploration, or wheel running. Results showed that running and sedentary mice displayed a nearly equivalent proportion of new neurons that expressed Zif268 following each task. Since running approximately doubled the number of new neurons, the results demonstrated that running mice had a greater number of new neurons recruited into the Zif268 induction in the granule cell layer following each task than sedentary mice. The results suggest that new neurons incorporated into hippocampal circuitry from running are not just activated by wheel running itself, but rather become broadly recruited into granule cell layer activity during distinct behavioral experiences. ? 2012 Wiley Periodicals, Inc.  相似文献   

18.
潘雪  刘冬 《生物多样性》2022,30(12):22193-80
甲螨是土壤动物主要的三大类群之一, 数量庞大且种类丰富。截至2020年, 中国已报道的甲螨仅占世界所有已知甲螨种类的7.6%, 这与我国已知甲螨种类真实物种状况仍有较大的差距。值此中国甲螨学开创100周年之际, 本研究以甲螨亚目为研究对象, 分别基于世界2020-2021年度和中国2007-2021年度发表的分类学文献资料, 编制了世界新增分类单元名录和近15年中国发表甲螨新种名录, 分析了新分类单元的地理分布、学者贡献和出版刊物情况。研究结果表明, 2020-2021年, 世界甲螨亚目共描述238个新分类单元, 包括新属及新亚属21个, 新种217个; 新分类单元发表的热点地区在埃塞俄比亚界、东洋界和新热带界; 描述的新分类单元由27位作者所贡献, 其中外国学者贡献占比高; 论文均发表在国外期刊上, Systematic and Applied Acarology是新分类单元发表的主要期刊。2007-2021年, 中国发表甲螨亚目新种183个, 无新科和新属发表; 新种发表的热点地区在华南区和西南区; 描述的新种由24位作者所贡献, 中国学者占主要贡献; 论文多发表在国外期刊上, Systematic and Applied AcarologyZootaxa是新分类单元发表的主要期刊。基于以上结果, 本文认为目前从事甲螨分类学研究的学者相对较少, 发表的新分类单元在类群分布和区域分布上均表现出极不均衡的现象。传统分类学未来的发展将面临机遇和挑战。  相似文献   

19.
Duplication of the single Golgi apparatus in the protozoan parasite Trypanosoma brucei has been followed by tagging a putative Golgi enzyme and a matrix protein with variants of GFP. Video microscopy shows that the new Golgi appears de novo, near to the old Golgi, about two hours into the cell cycle and grows over a two-hour period until it is the same size as the old Golgi. Duplication of the endoplasmic reticulum (ER) export site follows exactly the same time course. Photobleaching experiments show that the new Golgi is not the exclusive product of the new ER export site. Rather, it is supplied, at least in part, by material directly from the old Golgi. Pharmacological experiments show that the site of the new Golgi and ER export is determined by the location of the new basal body.  相似文献   

20.
基于特征属性的中国自然保护区分类体系   总被引:2,自引:0,他引:2  
基于114个自然保护区典型样本的特征属性,采用聚类分析方法建立了新的中国自然保护区分类体系.结果表明:与现行的国家分类标准相比,新的分类体系更具简明性和实用性;同时,新体系中的C1、C2、C3、C4类型分别与世界自然保护联盟(IUCN)分类体系中的Ⅰ、Ⅱ、Ⅳ、Ⅴ类保护区相对应.新体系保持了分类标准和尺度的一致性,一定程度上避免了主观分类的偏差,为中国自然保护区的分类提供了量化依据.  相似文献   

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