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1.
Molecular Biology Reports - Diabetic nephropathy (DN) is among the main complications of diabetes mellitus and has been a major factor of renal failure. This study was designed to address the...  相似文献   

2.

Background

Although being a simple and effective index that has been widely used to evaluate academic output of scientists, the h-index suffers from drawbacks. One critical disadvantage is that only h-squared citations can be inferred from the h-index, which completely ignores excess and h-tail citations, leading to unfair and inaccurate evaluations in many cases.

Methodology /Principal Findings

To solve this problem, I propose the h’-index, in which h-squared, excess and h-tail citations are all considered. Based on the citation data of the 100 most prolific economists, comparing to h-index, the h’-index shows better correlation with indices of total-citation number and citations per publication, which, although relatively reliable and widely used, do not carry the information of the citation distribution. In contrast, the h’-index possesses the ability to discriminate the shapes of citation distributions, thus leading to more accurate evaluation.

Conclusions /Significance

The h’-index improves the h-index, as well as indices of total-citation number and citations per publication, by possessing the ability to discriminate shapes of citation distribution, thus making the h’-index a better single-number index for evaluating scientific output in a way that is fairer and more reasonable.  相似文献   

3.
The ‘New Zealand flatworm’, Arthurdendyus triangulatus, is a native of the South Island of New Zealand, which has established in the UK, Ireland and the Faroe Islands. In its introduced range, it is a predator of lumbricid earthworms. To assess the impact of A. triangulatus on earthworm species, flatworm distributions were manipulated into ‘high’, control and ‘low’ densities within a replicated field experiment. Earthworm biomass in the ‘high’ flatworm density treatment was significantly lower than the control or ‘low’ treatments. This was due to a reduction in the anecic species Lumbricus terrestris and, to a lesser extent, Aporrectodea longa. There was little evidence of negative effects on other earthworm species, with even a weakly positive relationship between flatworm density and epigeic biomass. Principal components analysis showed a clear separation of anecic species from A. triangulatus, but the epigeic species Lumbricus festivus and Lumbricus rubellus grouped with A. triangulatus, suggesting that they could be benefitting from reduced intraguild competition. Flatworm densities of 0.8 per m2, comparable to natural infestations in grassland, were predicted to give a reduction in total earthworm biomass of c. 20 %. The bulk of this was comprised of a reduction in anecic species biomass. In particular, it is considered that A. triangulatus poses a serious risk to L. terrestris populations, with implications for soil functioning and indigenous earthworm-feeding wildlife.  相似文献   

4.
Dark grown Scenedesmus obliquus strain PG1 accumulated -carotene and phytoene as its major carotenoids. On illumination of dark-grown cultures in air/CO2, cyclic carotenes and xanthophylls were formed, apparently at the expense of the accumulated phytoene and -carotene. This interconversion of carotenoids was accompanied by chlorophyll synthesis. In an atmosphere of nitrogen/CO2 the light-induced changes occurred more slowly and in nitrogen alone the changes were incomplete. No massive production of cyclic carotenes from the accumulated -carotene was observed in cultures illuminated under anaerobic conditions.  相似文献   

5.
One-third of public school students are racial and/or ethnic minorities. Yet only 14 per cent of teachers represent these groups. Frequently lost in broader debates concerning this disparity is the paradoxical contribution of the 1954 Brown v. Board of Education decision. Schools were mandated under Brown to desegregate the student body. But the law did not necessarily protect the jobs of black teachers and administrators. Using a unique database of court orders, we examine the impact of mandated desegregation on black teachers. Findings indicate regional differences. Mandated desegregation created conditions that resulted in decreases in the black teaching force in the South. The opposite occurred in the non-south, with mandated desegregation positively associated with increases (although small) in the black teaching force. Our findings suggest that the legacy of mandated desegregation may have created broader institutional conditions in which black and other minority teachers remain underrepresented in the teaching force.  相似文献   

6.
The good,the bad and the ugly?   总被引:3,自引:0,他引:3  
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7.
The human interleukin-6 receptor chain (IL6R) gene was regionally mapped to chromosome 1 bridization probes, partially overlapping lambda clones encompassing 28 kb of the genomic region of the gene were used. These clones were isolated using a polymerase chain reaction (PCR)-generated fragment of the 3 noncoding region of the gene. This localization confirms and extends the provisional assignment of the IL6R gene to chromosome 1, for which a panel of somatic cell hybrids was used.  相似文献   

8.
Interleukin-15 receptor alpha (IL-15R alpha) is a high affinity IL-15 binding protein that is crucial for mediating IL-15 functions such as memory CD8 T cell proliferation and NK, NK/T cell, and intestinal intraepithelial lymphocyte development. However, the mechanism by which IL-15R alpha mediates IL-15 functions is unique among cytokines. Originally, IL-15R alpha was thought to be a component of a heterotrimeric receptor complex containing the IL-2/IL-15R beta and common gamma chains (gammaC) that were required for mediating signaling. Although IL-15R alpha may in some cases act as a component of this receptor complex, more recent evidence indicates that IL-15R alpha predominately functions by presenting IL-15 to opposing cells expressing the IL-15R betagamma signaling components. This theory is consistent with the broad, non-lymphoid expression pattern of IL-15R alpha and the evidence that IL-15R alpha expression by lymphocytes is dispensable for IL-15 action in vivo. This new concept of cytokine delivery will allow us to better understand the regulation and function IL-15.  相似文献   

9.
In the literature there appears to be variability in reported levels of certain hormones during haemorrhage, specifically adrenocorticotrophic hormone (ACTH) and β-endorphin. It is possible that this variability may be due to the choice of anaesthetic. Therefore, the effect of 3 common research-only anaesthetic agents (alphaxalone-alphadolone, propofol, and pentobarbitone) on ACTH and β-endorphin levels during haemorrhage was assessed in pigs. Animals were divided into 3 groups: group I received alphaxalone-alphadolone (n = 5), group II received propofol (n = 6), and group III received pentobarbitone (n = 6). Pigs were subjected to a continuous fixed-volume haemorrhage under one of the above anaesthetics while being mechanically ventilated. ACTH and β-endorphin levels increased significantly during haemorrhage under propofol and pentobarbitone anaesthesia but not with alphaxalone-alphadolone. For ACTH there was no significant difference between the groups, whereas for β-endorphin there was a significant difference between the propofol- and pentobarbitone-anaesthetized pigs. The increase in heart rate during haemorrhage was significantly different between the alphaxalone-alphadolone and propofol as well as between the propofol and pentobarbitone groups. The drop in blood pressure was only significantly different between the alphaxalone-alphadolone- and propofol-anaesthetized pigs. These results indicate that the choice of anaesthetic agent can affect the hormone response to haemorrhage and may account for the variable hormone levels reported in the published literature to date.  相似文献   

10.
Summary An attempt has been made to find out the productivity and periodicity of the phytoplankton in relation to the physical and chemical characteristics of the river Ganges, between University Ghat and Raj Ghat at Varanasi. The observations were taken during a single year (i.e., March 1957 to March 1958). The chemical analyses of the water and estimates of the number of phytoplankton were made on samples collected fortnightly.The phytoplankton has proved to be eutrophic and polymixic in nature. Diatoms formed the largest bulk, blue-greens being the second major constituent while the green algae formed the third in order of abundance with, however, large number of species. A definite phytoplankton periodicity has been noticed and found to be seasonal in character.Correlations between the phytoplankton periodicity and population maxima, with the habitat factors revealed depletion of nutrients like, nitrogen, phosphate, silica, carbon, magnesium and sulphates.Changes in the phytoplankton populations were clearly evident more in relation to physical than to chemical conditions of the water. Changes in water-level, transparency and temperature affected the growth of the phytoplankton.High alkalinity and buffering capacity resulted in preferential growth of diatoms and blue-green algae. Rich phosphates and silicates coupled with moderate nitrogen contents were responsible for high phytoplankton yields in summer and winter seasons.The abundance of blue-greens may be due to the higher values of pH, temperature, dissolved organic matter, phosphate, nitrogen, and relatively high values of dissolved oxygen. Green algae showed a wide range of adaptability but could not develop in any abundance.  相似文献   

11.
The lion’s share of studies on regeneration in Plathelminthes (flatworms) has been so far carried out on a derived taxon of rhabditophorans, the freshwater planarians (Tricladida), and has shown this group’s outstanding regeneration capabilities in detail. Sharing a likely totipotent stem cell system, many other flatworm taxa are capable of regeneration as well. In this paper, we present the regeneration capacity of Macrostomum lignano, a representative of the Macrostomorpha, the basal-most taxon of rhabditophoran flatworms and one of the most basal extant bilaterian protostomes. Amputated or incised transversally, obliquely, and longitudinally at various cutting levels, M. lignano is able to regenerate the anterior-most body part (the rostrum) and any part posterior of the pharynx, but cannot regenerate a head. Repeated regeneration was observed for 29 successive amputations over a period of almost 12 months. Besides adults, also first-day hatchlings and older juveniles were shown to regenerate after transversal cutting. The minimum number of cells required for regeneration in adults (with a total of 25,000 cells) is 4,000, including 160 neoblasts. In hatchlings only 1,500 cells, including 50 neoblasts, are needed for regeneration. The life span of untreated M. lignano was determined to be about 10 months.An erratum to this article can be found at  相似文献   

12.
This paper explores the relationship between the economic turmoil generated by the Great Recession and the increase of secessionism. Some authors have stressed that the Great Recession triggered changes in territorial preferences and, in the context of a conflict between the centre and the periphery, fuelled secessionism as a radical shift of the institutional setup. Nevertheless, other researchers have remarked that a recession may enhance the status quo bias and decrease the likelihood of changes. Our paper aims at contributing to this debate by analysing the case of Catalonia. We use an aggregate and an individual-level empirical design to explore the relationship between the deterioration of the economic situation and the increase of preferences for secession among the Catalan population. The findings from the analysis of our empirical models do not support the hypothesis that the effects of the Great Recession had any significant impact on political preferences in Catalonia.  相似文献   

13.
Small β-hairpin peptides have been widely used as models for the folding of β-sheets. But how applicable is the folding of such models to β-structure in larger proteins with conventional hydrophobic cores? Here we present multiple unfolding simulations of three such proteins that contain the WW domain double hairpin β-sheet motif: cold shock protein A (CspA), cold shock protein B (CspB) and glucose permease IIA domain. We compare the behavior of the free motif in solution and in the context of proteins of different size and architecture. Both Csp proteins lost contacts between the double-hairpin motif and the protein core as the first step of unfolding and proceeded to unfold with loss of the third β-strand, similar to the isolated WW domain. The glucose permease IIA domain is a larger protein and the contacts between the motif and the core were not lost as quickly. Instead the unfolding pathway of glucose permease IIA followed a different pathway with β1 pulling away from the sheet first. Interestingly, when the double hairpin motif was excised from the glucose permease IIA domain and simulated in isolation in water it unfolded by the same pathway as the WW domain, indicating that it is tertiary interactions with the protein that alter the motif’s unfolding not a sequence dependent effect on its intrinsic unfolding behavior. With respect to the unfolding of the hairpins, there was no consistent order to the loss of hydrogen bonds between the β-strands in the hairpins in any of the systems. Our results show that while the folding behavior of the isolated WW domain is generally consistent with the double hairpin motif’s behavior in the cold shock proteins, it is not the case for the glucose permease IIA domain. So, one must be cautious in extrapolating findings from model systems to larger more complicated proteins where tertiary interactions can overwhelm intrinsic behavior.  相似文献   

14.
15.
Testes removed from Schistocerca gregaria, injected with 5 or 7&mgr;g azadirachting(-1) body wt on day 0-2 of the Vth instar and killed by decapitation 20days after treatment, showed significant reductions between the widths, lengths and volumes of the treated groups, compared to control insects. Under cytological examination these testes, from insects exhibiting classical signs of azadirachtin poisoning, showed arrested spermatogenic meiosis at Metaphase I.  相似文献   

16.
17.
《Acta Oecologica》1999,20(3):147-158
Sample sites of `brousse tigrée' and related vegetation types are described for Mali and Niger. Species composition and physical structure of the herbaceous layer as well as woody plant population were recorded at all sites together with data on soils and natural resource management. Herbage yield was measured whereas foliage yield and wood mass were calculated using allometry equation calibrated for each species. `Brousse tigrée' is characterized by the regularly alternating bare-soil stripes with dense linear thickets arranged perpendicularly to the slope. There was no clear superiority in total plant production of `brousse tigrée' when compared to neighbouring site with diffuse vegetation. However, the pattern of `brousse tigrée' tended to favour woody plant yield to the detriment of herbage yield. The number of herbaceous species recorded per site (22–26) was slightly above Sahelian vegetation average despite low number of species per 1-m2 quadrat (6–9), bare soil excluded. This species richness reflects the diversity in edaphic niches resulting from the redistribution and local concentration of water resources and shade. The high spatial heterogeneity and species richness of the herbaceous layer in `brousse tigrée' did not attenuate the interannual variation in herbage yield despite low yields. Except for the herb layer, little evidence was found of grazing influence on the vegetation structure and yield a few hundred metres away from livestock concentration points. On the other hand, the clearing of thickets for cropping led to severe soil erosion which threaten the resilience of `brousse tigrée'. These observations and the well-defined climatic, soiland topographic situations under which the `brousse tigrée' occurs invalidate the hypothesis of an anthropic origin of that vegetationpattern.  相似文献   

18.
Dinoflagellates in the genus Symbiodinium are among the most abundant and important group of eukaryotic microbes found in coral reef ecosystems. Recent analyses conducted on various host cnidarians indicated that Symbiodinium assemblages in the Caribbean Sea are genetically and ecologically diverse. In order to further characterize this diversity and identify processes important to its origins, samples from six orders of Cnidaria comprising 45 genera were collected from reef habitats around Barbados (eastern Caribbean) and from the Mesoamerican barrier reef off the coast of Belize (western Caribbean). Fingerprinting of the ribosomal internal transcribed spacer 2 identified 62 genetically different Symbiodinium. Additional analyses of clade B Symbiodinium using microsatellite flanker sequences unequivocally characterized divergent lineages, or “species,” within what was previously thought to be a single entity (B1 or B184). In contrast to the Indo-Pacific where host-generalist symbionts dominate many coral communities, partner specificity in the Caribbean is relatively high and is influenced little by the host’s apparent mode of symbiont acquisition. Habitat depth (ambient light) and geographic isolation appeared to influence the bathymetric zonation and regional distribution for most of the Symbiodinium spp. characterized. Approximately 80% of Symbiodinium types were endemic to either the eastern or western Caribbean and 40–50% were distributed to compatible hosts living in shallow, high-irradiance, or deep, low-irradiance environments. These ecologic, geographic, and phylogenetic patterns indicate that most of the present Symbiodinium diversity probably originated from adaptive radiations driven by ecological specialization in separate Caribbean regions during the Pliocene and Pleistocene periods.  相似文献   

19.
BackgroundMindfulness as a mode of sustained and receptive attention promotes openness to each incoming stimulus, even if repetitive and/or aversive. Mindful attention has been shown to attenuate sensory habituation in expert meditators; however, others were not able to replicate this effect. The present study used acoustic startle reflex to investigate the effect of mindfulness practice intensity on sensory habituation.MethodsAuditory Startle Response (ASR) to 36 startling probes (12 trials x 3 block with 40ms inter-block intervals), was measured using electromyography (EMG) in three groups of participants (N = 12/group): meditation-naïve, moderate practice, and intensive practice.ResultsIntensive practice group showed attenuated startle habituation as evidenced by significantly less habituation over the entire experiment relative to the meditation-naïve and moderate practice groups. Furthermore, there was a significant linear effect showing between-block habituation in meditation-naïve and moderate practice groups, but not in the intensive practice group. However, the Block x Group interaction between the intensive practice and the meditation-naive groups was not significant. Moderate practice group was not significantly different from the meditation-naïve in the overall measure of habituation, but showed significantly stronger habituation than both meditation-naïve and intensive practice groups in Block 1. Greater practice intensity was significantly correlated with slower overall habituation and habituation rate in Blocks 2 and 3 in the intensive, but not in the moderate, practice group.ConclusionsThe study provides tentative evidence that intensive mindfulness practice attenuates acoustic startle habituation as measured by EMG, but the effect is modest. Moderate practice, on the other hand, appears to enhance habituation, suggesting the effect of mindfulness practice on startle habituation might be non-liner. Better understanding of the effect of mindful attention on startle habituation may shed new light on sensory information processing capacity of the human brain and its potential for de-automatisation of hard-wired processes.  相似文献   

20.
The supplementation with 50, 100 and 150μg/mL potassium chloride to the fifth instar larvae of the silkworm Bombyx mori on fat body glycogen, protein, total lipids and haemolymph protein and trehalose were analyzed. The fat body glycogen and protein and haemolymph protein were increased significantly in all the treated groups; whereas fat body total lipids increased only in 100 and 150μg/mL and haemolymph trehalose increased only in 150μg/mL potassium chloride-treated groups when compared with those of the corresponding parameters of the carrier controls.  相似文献   

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