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61.
Hall DW Kirkpatrick M West B 《Evolution; international journal of organic evolution》2000,54(6):1862-1869
We introduce models for the runaway coevolution of female mating preferences and male display traits. The models generalize earlier results by allowing for direct natural selection on the preference, arbitrary forms of mate choice, and fairly general assumptions about the underlying genetics. Results show that a runaway is less likely when there is direct selection on the preference, but that it is still possible if there is a sufficiently large phenotypic correlation between the female's preference and the male's trait among mated pairs. Comparison of three preference functions introduced by Lande (1981) shows that open-ended preferences are particularly prone to a runaway, and that absolute preferences require very large differences between females in their preferences. We analyze the causes of the runaway seen in a model developed by Iwasa and Pomiankowski (1995). 相似文献
62.
为正确认识蕉木(Oncodostigma hainanense)内轮花瓣近轴面突起的发育和作用,采用扫描电子显微镜(SEM)观察蕉木内轮花瓣近轴面瘤状突起的形成过程,并采用光学显微镜(LM)观察经PAS染色反应的蕉木内轮花瓣半薄切片的结构。SEM观察发现,蕉木花蕾在发育Ⅰ期和Ⅱ期其内轮花瓣近轴面无明显瘤状突起形成,Ⅲ期有明显的瘤状突起形成,Ⅳ期瘤状突起发育成熟并布满整个内轮花瓣近轴面;LM观察发现,多糖类物质随蕉木内轮花瓣近轴面瘤状突起的发育而增多,并向瘤状突起周边细胞集中;体视显微镜下观察到有蓟马的幼虫在开放的花瓣瘤状突起间活动,但并没有发现瘤状突起表面有泌蜜孔及多糖类物质。推测蕉木内轮花瓣近轴面瘤状突起为访花者提供了繁殖、产卵和孵卵的场所并为它们提供了一定的食物来源(多糖物质)。 相似文献
63.
2005年3月至2006年3月,采取所有事件取样法,对成都动物园5只(2雄,3雌)圈养金钱豹(Panthera pardu)进行观察,旨在了解圈养金钱豹的交配情况。记录交配行为1 174次。结果显示,圈养金钱豹全年皆可发情。具有明显的交配模式,交配姿势仅有一种,为背腹式。平均交配持续天数为(4.75±1.26)d。昼夜都有交配行为,但白天交配次数较夜间多。日交配的高峰发生在08:00~10:00时,不同的雄性个体出现的交配高峰日不同。平均交配持续时间为(7.48±1.22)s。在交配持续时间(P=0.000)、总交配次数(P=0.04)上,不同的雄性个体间存在显著性差异;而同一雄性在与不同雌性交配时,其持续时间无显著差异。金钱豹交配的特点为,交配的频次多,但每次交配持续时间短。 相似文献
64.
65.
Organisms are exposed to various stresses caused by environmental fluctuations. One of the most common stresses is the shortage of food. Individuals of many species must survive periods of starvation. There appears to be a trade‐off between reproduction and survival. When residual reproductive value declines for an individual, life‐history theory predicts an increase in current reproductive investment. Current reproductive investment differs between virgin and mated individuals. It is likely that mating experience influences starvation tolerance. However, few studies have investigated sex differences in the effect of mating experience on starvation tolerance or clarified the causes of reductions in starvation tolerance in both sexes. In the present study, these questions are investigated using the seed bug Togo hemipterus (Heteroptera: Lygaeidae).The results of the present study demonstrate that mating is costly for both sexes. Mated males show very short survival times and a daily reduction in weight, and daily energy expenditures are significantly greater in mated males than in virgin males. It is possible that starvation increases the mating effort of males, such as behavioural activities and the amount of time spent searching for females. A trade‐off between survival duration and lifetime fecundity is found in virgin females. However, there is no trade‐off in mated females, which have very short survival times. Whether male seminal substances contribute to the short survival times of mated females is considered. This is the first report demonstrating the influence of sex and mating experience on starvation tolerance. Sex‐specific causes for reductions in starvation tolerance are discussed. 相似文献
66.
Mammalian mating systems are thought to be shaped by the spatial distribution and abundance of key resources, which in turn
influence the spacing behaviour of individuals. In particular, female home range size is predicted to reflect the availability
of key resources. We documented the availability and distribution of food and shelter resources for two neighbouring populations
of bobucks, or mountain brushtail possums, Trichosurus cunninghami, that were characterised by different mating systems: our “forest population” was socially monogamous, whereas the “roadside
population” was polygynous. Both silver wattle, Acacia dealbata, the main food resource for bobucks, and den-trees, which provided shelter, occurred at significantly higher density at the
roadside site. The pattern of distribution of these two resources also differed between the sites. Both food and den-trees
were scattered evenly throughout the roadside habitat. In contrast, den-trees were located predominantly at one end of the
forest site, while silver wattle trees were located at the other. There was no significant difference in the amount of silver
wattle, or in the number of den-trees, located within the home ranges of individual females at the two sites. However, forest
females had home ranges, on average, almost three times the size of those of roadside females. At the roadside site, the size
of female home ranges varied inversely with the density of silver wattle, indicating that these females ranged over as large
an area as necessary to gain access to sufficient silver wattle trees. There was no such relationship among forest females.
These populations provide a clear example of resource distribution determining female home range size. This influenced the
number of female home ranges a male’s home range overlapped with, which in turn determined the mating system. Such clear links
between resource availability and mating system have not previously been established in a marsupial. 相似文献
67.
Bateman’s principles of sexual selection predict that the sex with “cheaper” gametes may maximize reproductive efforts by
mating multiply and so display greater positive covariance between reproductive and mating success. We conducted a semi-controlled
breeding experiment to genetically quantify sexual selection in adult Ambystoma texanum, a sexually monomorphic salamander with simple courtship behaviors. We used four polymorphic microsatellite loci to genotype
57 adults enclosed in a breeding wetland and compared their multilocus profiles to that of 862 embryos collected from the
enclosure. The molecular data were used to assign parentage, investigate the mating system, and measure sexual selection intensity.
Parentage analyses indicated 36% of dams and 93% of sires were genetically sampled via their gametes but physically unsampled,
suggesting that a large number of breeders over-wintered within the enclosure and/or some females released into the enclosure
were already inseminated. We used the genetic data to generate estimates of individual reproductive and mating success and
we interpret these in light of salamander behavior and sexual selection theory. The incidence of multiple mating in females
(86%) was considerably higher than in males (32%) and the standardized variance in mating success was significantly greater
in females. The correlations between reproductive and mating success were significant and of similar magnitude between the
sexes, indicating that both sexes increased reproductive success through increased mating success. This pattern may be a function
of differential opportunities for mating success between the sexes.
Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
68.
Insect workers can increase their inclusive fitness by biasing colony sex allocation towards males when their mother queen is mated to multiple males and females when she is singly mated. Workers need heritable variation in odour diversity to assess queen mating frequency. Here we present a simple one-locus two-allele model, which shows that the sex ratio specialization itself will often select against rare alleles that would provide additional information for the assessment of queen mating frequency. However, under certain rather restricted conditions, such as when sex ratios are highly female biased, and when worker reproduction is rare, sex ratio specialization can select for rare alleles. This suggests that sex allocation biasing by workers will usually reduce the very information that workers need to assess queen mating frequency. Our model is an example where an explicit treatment of underlying genetics and mechanisms of behaviour, such as information use, is necessary to fully understand the evolution of an adaptive behavioural strategy. 相似文献
69.
Mark van Kleunen 《Evolutionary ecology》2007,21(2):185-199
The optimal allocation to sexual and vegetative reproduction as well as the optimal values of other life-history characteristics
such as phenology, growth and mating system are likely to depend on the life-cycle of the organism. I tested whether plants
of Mimulus guttatus originating from temporarily wet populations where the species has an enforced annual life-cycle have higher allocation to
sexual reproduction, lower allocation to vegetative reproduction, more rapid phenology, faster growth, and floral traits associated
with a self-fertilizing mating system than plants from permanently wet populations where the species has a perennial life-cycle.
I grew a total of 1377 plants originating from three populations with an annual life-cycle and 11 populations with a perennial
life-cycle in a greenhouse under permanently and temporarily wet conditions. Plants of M. guttatus in permanently wet conditions had significantly more vegetative reproduction and tended to have a faster growth than plants
in the temporarily wet conditions, indicating plasticity in these life-history traits. Plants from populations with an annual
life-cycle invested significantly more in sexual reproduction and significantly less in vegetative reproduction than the ones
from populations with a perennial life-cycle. Moreover, this study showed that plants originating from populations with an
annual life-cycle have a significantly faster development and floral traits associated with autonomous self-fertilization.
In conclusion, this study suggests that there has been adaptive evolution of life history traits of M. guttatus in response to natural watering conditions that determine the life span of the species. 相似文献
70.
Colin J. Yates David J. Coates Carole Elliott Margaret Byrne 《Biodiversity and Conservation》2007,16(5):1379-1395
In this study we investigate the composition of the potential honeyeater pollinator community, patterns of honeyeater visitation,
pollination and the mating system in a range of population fragments for the bird-pollinated mixed mating system shrub Calothamnus quadrifidus R.Br. Specifically, we aimed to answer the following questions. For smaller and more isolated population fragments are honeyeater
species lost from the pollinator community, patterns of visitation different, levels of pollination lower and rates of selfing,
biparental inbreeding and correlated paternity higher. The composition of the honeyeater community was similar across population
fragments and there was no relationship between the abundance of birds and population fragment size. Honeyeaters were most
commonly observed visiting numerous inflorescences within single plants in all populations, but as population fragments became
larger movements between plants were more commonly observed. Our observations of honeyeater visitation were generally consistent
with our measurements of pollination and patterns in the mating system across population fragments. We found no significant
relationship between population fragment size and levels of pollination. Mating system studies showed outcrossing rates (t
m) comparable to those found in other bird-pollinated Myrtaceae, and ranged from 0.54 to 0.90 across populations. Outcrossing
rates were not significantly correlated with log population size, but correlations of outcrossed paternity indicate a clear
trend from low correlated paternity in larger populations to significantly higher correlated paternities in smaller populations.
As a consequence mating in small populations will occur between much smaller groups of plants, and this may affect population
fitness in subsequent generations. 相似文献