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11.
Cristiana Vitale Giuseppe Mercuro Carlotta Castiglioni Alessandra Cornoldi Arianna Tulli Massimo Fini Maurizio Volterrani Giuseppe MC Rosano 《Cardiovascular diabetology》2005,4(1):1-8
Background
Metabolic syndrome is a cluster of common cardiovascular risk factors that includes hypertension and insulin resistance. Hypertension and diabetes mellitus are frequent comorbidities and, like metabolic syndrome, increase the risk of cardiovascular events. Telmisartan, an antihypertensive agent with evidence of partial peroxisome proliferator-activated receptor activity-gamma (PPARγ) activity, may improve insulin sensitivity and lipid profile in patients with metabolic syndrome.Methods
In a double-blind, parallel-group, randomized study, patients with World Health Organization criteria for metabolic syndrome received once-daily doses of telmisartan (80 mg, n = 20) or losartan (50 mg, n = 20) for 3 months. At baseline and end of treatment, fasting and postprandial plasma glucose, insulin sensitivity, glycosylated haemoglobin (HBA1c) and 24-hour mean systolic and diastolic blood pressures were determined.Results
Telmisartan, but not losartan, significantly (p < 0.05) reduced free plasma glucose, free plasma insulin, homeostasis model assessment of insulin resistance and HbAic. Following treatment, plasma glucose and insulin were reduced during the oral glucose tolerance test by telmisartan, but not by losartan. Telmisartan also significantly reduced 24-hour mean systolic blood pressure (p < 0.05) and diastolic blood pressure (p < 0.05) compared with losartan.Conclusion
As well as providing superior 24-hour blood pressure control, telmisartan, unlike losartan, displayed insulin-sensitizing activity, which may be explained by its partial PPARγ activity. 相似文献12.
Individuals of some species of Mammillaria (Cactaceae) store some seeds on the plant over periods exceeding 1 year (serotiny). We examined the phenomenon of serotiny and germination behaviour of three rare and endangered Mammillaria species that occur in central Mexico. The species with the highest seed retention was Mammillaria solisioides, whose individuals kept on average 24% of their total seed crop throughout their observable lifetime. Individuals of Mammillaria napina and Mammillaria hernandezii did not differ in their degree of seed retention (about 5%). In M. solisioides and M. hernandezii, seed germination declined significantly with seed age, whereas in M. napina germination increased slightly. In all three species, over 70% of retained seeds were still alive after 8 years. Increasing fractions of dormant seeds were observed with seed age in M. solisioides and M. hernandezii, whereas in M. napina this fraction followed the opposite trend. All three species showed strict light dependence for germination. Serotiny was positively correlated with the harshness of the environment when species and populations were assumed independent. However, these correlations were not significant at the 5% level when the degree of relatedness of species and populations was taken into account using phylogenetically independent constrasts. We hypothesise that serotiny in these species represents a mechanism by which they can cope with a harsh, unpredictable environment. To our knowledge, this is the first assessment of serotiny in cacti. 相似文献
13.
Clark Tapia Ricardo Cecilia Alfonso Corrado María C. Mandujano Francisco Molina-Freaner 《Evolutionary ecology》2006,20(2):131-142
Stenocereus eruca is a prostrated, self-incompatible cactus endemic to the Sonoran Desert that regenerates primarily through clonal propagation.
Clonal growth is expected to affect mate availability by influencing the number and spatial distribution of mating types.
In this paper we examine the role of clonal growth on female fecundity through a series of pollination experiments in a population
of S. eruca. We set up a pollen supplementation experiment using five distance treatments with pollen collected at 1, 10, 100, 1000 and
25000 m from receptor flowers during the years 2001 and 2002 and evaluated genetic sifmilarities between pairs of receptor-donor
ramets through RAPD markers. Our data on fruit set, number of seeds/fruit, germination and overall fecundity revealed that
S. eruca show a significant reduction in female fecundity when pollination occurs between ramets located at short distances (1 and
10 m), while genetic data showed high levels of similarity at those distances. The reduction in female fecundity is apparently
a consequence of geitonogamy and inbreeding depression. Our data suggest that clonal growth and geitonogamy are likely to
be partially responsible for the low levels of sexual reproduction and seedling recruitment observed in populations of S. eruca.
Co-ordinating editor: H. Kudoh 相似文献
14.
Patrick LJM Zeeuwen Jos Boekhorst Ellen H van den Bogaard Heleen D de Koning Peter MC van de Kerkhof Delphine M Saulnier Iris I van Swam Sacha AFT van Hijum Michiel Kleerebezem Joost Schalkwijk Harro M Timmerman 《Genome biology》2012,13(11):R101
Background
Recent advances in sequencing technologies have enabled metagenomic analyses of many human body sites. Several studies have catalogued the composition of bacterial communities of the surface of human skin, mostly under static conditions in healthy volunteers. Skin injury will disturb the cutaneous homeostasis of the host tissue and its commensal microbiota, but the dynamics of this process have not been studied before. Here we analyzed the microbiota of the surface layer and the deeper layers of the stratum corneum of normal skin, and we investigated the dynamics of recolonization of skin microbiota following skin barrier disruption by tape stripping as a model of superficial injury.Results
We observed gender differences in microbiota composition and showed that bacteria are not uniformly distributed in the stratum corneum. Phylogenetic distance analysis was employed to follow microbiota development during recolonization of injured skin. Surprisingly, the developing neo-microbiome at day 14 was more similar to that of the deeper stratum corneum layers than to the initial surface microbiome. In addition, we also observed variation in the host response towards superficial injury as assessed by the induction of antimicrobial protein expression in epidermal keratinocytes.Conclusions
We suggest that the microbiome of the deeper layers, rather than that of the superficial skin layer, may be regarded as the host indigenous microbiome. Characterization of the skin microbiome under dynamic conditions, and the ensuing response of the microbial community and host tissue, will shed further light on the complex interaction between resident bacteria and epidermis. 相似文献15.
The demographic costs of nectar production in the desert perennial Prosopis glandulosa (Mimosoideae): a modular approach 总被引:1,自引:0,他引:1
Golubov Jordan Mandujano María C. Montaña Carlos López-Portillo Jorge Eguiarte Luis E. 《Plant Ecology》2004,170(2):267-275
Nectar production in angiosperms is considered to represent a reproductive cost, and has been associated with a decrease in
fruit set or an overall decrease in the energetic budget of the plant. Populations of Prosopis glandulosa var. torreyana (honey mesquite) are a suitable system to evaluate the demographic costs of nectar production, as populations are composed
of a 1:1 proportion of nectarful to nectarless individuals. The study was carried out in a population of 404 individuals of
Prosopis g1andulosa var. torreyana found in an area with differing water availability in the Southern Chihuahuan Desert. The possible costs of nectar production
were assessed on 1212 shoots of the honey mesquite that were tagged in 1994 and followed until 1998. We used two methods of
analysis to describe the effect of nectar production on modular population dynamics: matrix analysis and log-xlinear models.
Water availability and the varying environmental conditions affected plant growth, but nectar production did not have an effect
on the demographic parameters we measured. The values of λ did not differ between nectar morphs and the only important effects
we detected were the year to year variation in precipitation and microclimate differences at each site. Furthermore, the elasticity
of each demographic process (growth, fecundity, retrogression and stasis) between nectar morphs did not differ. The log-linear
models suggested a similar pattern but could discriminate the importance of each factor (nectar morph, year and site) on module
fate. We were not able to detect a demographic cost of nectar production in the honey mesquite. The absence of a demographic
response could be due to the negligible cost of producing nectar for this species or that the resources allocated for growth
are different from those allocated for reproduction. Our results suggest that the modular fates of mesquites are mainly determined
by environmental factors.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
Omar Díaz-Segura Jordan Golubov María C. Mandujano José Alejandro Zavala-Hurtado 《Plant Species Biology》2020,35(4):270-282
Reproductive systems are life attributes important in defining the demography and genetic constitution of invasive alien species populations. We describe the phenology, floral behavior and floral visitors in Mexican populations of Leonotis nepetifolia considered invasive in America, Asia and Oceania. The mating system was determined through pollination experiments and, with a morphological analysis of flowers (outcrossing index, OCI) and pollen/ovule ratio, the breeding system was evaluated. Germination of 1 and 2-year-old seeds was tested to assess the potential characteristics of germination. Leonotis nepetifolia was reproductive for 7 months (June to December) and tended towards a specific season during autumn. Anthesis lasted 36 hr with protogyny and no hercogamy, with floral visitors of Apodiformes, Hymenoptera, Lepidoptera and Thysanoptera. Pollination experiments indicated a mixed mating system, whereas the OCI and the pollen/ovule ratio pointed towards a facultative xenogamous breeding system. Seed production was high (1,445 ± 132 seeds/plant); the seeds had potential longevity and were neutral photoblastic. One-year-old seeds germinated slightly later ( = 2.6 ± 0.11 days) than 2-year-old seeds ( = 1.9 ± 0.02 days), both synchronously (IS1yr = 0.88 ± 0.03 and IS2yr = 0.82 ± 0.02). Germination percentage for 1-year-old seeds was lower (55.33 ± 4.40%) than that of 2-year-old seeds (94.18 ± 0.59%), suggesting a potential longevity of the seeds in an optimal environment. Reproductive characteristics, such as wide reproductive period, mixed breeding system, copious seed production, seeds with potential longevity, and quick and synchronic germination in different light conditions, favor the invasive capacity of Leonotis nepetifolia. 相似文献
17.
18.
Josiah MC Heyman 《The journal of the Royal Anthropological Institute》2000,6(4):635-652
High-scale morality is the study of moral ideas and sentiments deployed in relations that encompass multiple, geographically or socially distant populaces. The envisioning of distant people, their attributed moral personhood, the evaluation of their perceived behaviour, and the rectification of wrongs through the use of powerful organizations are key topics in high-scale morality. High-scale morality differs from existing anthropological approaches that emphasize local ethnography or contrastive moral ideas; it addresses the moralization of issues like world hunger, the drug trade, or international migration. The officers of the US Immigration and Naturalization Service understand and evaluate legal and illegal immigrants, as well as directly enacting moral rectification for the US polity. As they resolve moral dilemmas on their job, they utilize pervasive models for moral thought and action in capitalist, individualist, stratified, and bureaucratized societies. The article finishes by considering directions in which anthropology can contribute to understanding the moral dimension of global issues. 相似文献
19.
20.
The dynamics of plant populations in arid environments are largely affected by the unpredictable environmental conditions
and are fine-tuned by biotic factors, such as modes of recruitment. A single species must cope with both spatial and temporal
heterogeneity that trigger pulses of sexual and clonal establishment throughout its distributional range. We studied two populations
of the clonal, purple prickly pear cactus, Opuntia macrocentra, in order to contrast the factors responsible for the population dynamics of a common, widely distributed species. The study
sites were located in protected areas that correspond to extreme latitudinal locations for this species within the Chihuahuan
Desert. We studied both populations for four consecutive years and determined the demographic consequences of environmental
variability and the mode of reproduction using matrix population models, life table response experiments (LTREs), and loop
and perturbation analyses. Although both populations seemed fairly stable (population growth rate, λ∼1), different demographic parameters and different life cycle routes were responsible for this stability in each population.
In the southernmost population (MBR) LTRE and loop and elasticity analyses showed that stasis is the demographic process with
the highest contributions to λ, followed by sexual reproduction, and clonal propagation contributed the least. The northern population (CR) had both higher
elasticities and larger contributions of stasis, followed by clonal propagation and sexual recruitment. Loop analysis also
showed that individuals in CR have more paths to complete a life cycle than those in MBR. As a consequence, each population
differed in life history traits (e.g., size class structure, size at sexual maturity, and reproductive value). Numerical perturbation
analyses showed a small effect of the seed bank on the λ of both populations, while the transition from seeds to seedlings had an important effect mainly in the northern population.
Clonal propagation (higher survival and higher contributions to vital rates) seems to be more important for maintaining populations
over long time periods than sexual reproduction. 相似文献