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31.
We studied the effects of kinship, age, sex, and other factors on patterns of spatial proximity among group members in a wild group of moor macaques (Macaca maurus) in Sulawesi, Indonesia. We assessed the importance of each factor via multiple linear regression analyses. Moor macaques stay close to their matrilineal relatives more frequently when the group moves or rests than when they feed. Subjects of similar age, sex, or rank tended to stay close to each other. Females were in the proximity of females with newborn infants regardless of the phase of activity of the group. Kinship may have less effect on proximity during feeding in moor macaques than in Japanese macaques. Weak effects of kinship during feeding may result from weak contest competition for food within the group.  相似文献   
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33.
Studies of fertility behavior in the Third World have relied heavily on two variables, income and education, to explain variations in fertility rates. If the socio-economic variables traditionally employed to account for variations in fertility rates are invariant, what other factors could influence fertility rates and child spacing? On the basis of data from 180 slum households in Calcutta, India, the paper indicates that in a situation where material and social conditions are comparable, cultural and demographic variables play a major role in influencing reproductive behavior. In this case study, caste and family type are shown to have a significant effect on the numbers of surviving children. As regards child spacing, the woman's age is of paramount importance.  相似文献   
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35.
Sexual selection has received a great deal of attention from field and laboratory researchers for over a century, but hard evidence of female choice of mates in mixed-sex groups remains scarce. Dominant males typically mate much more often than subordinants but evidence that females “choose” such males is elusive. In Gallus, which includes junglefowl and their domestic fowl descendants, females stay near and mate with dominant, territorial males. We demonstrate here that Gallus females in mixed-sex flocks who have no information about the social dominance status of males orient to, approach and stay near males with larger than average combs whereas females which do not have information about male dominance orient toward and stay near high ranking males. We verify that comb size correlates with male social rank. Hence, Gallus females do actively respond to “high quality” males; they apparently identify such males by male physical characteristics and, if available, information concerning male-male interactions.  相似文献   
36.
Ultrasound scatter-spacing based diagnosis of focal diseases of the liver   总被引:1,自引:0,他引:1  
Ultrasound returns from liver shows periodicity arising from periodic scattering centers within tissue. Focal diseases such as tumors interrupt this structure. In this paper, we propose the use of a wavelet transform based technique to estimate the inter-scatterer-distribution (ISS) in diagnosing focal diaseases of the liver. The efficacy of the method is illustrated with simulated and clinical ultrasound images. The mean value (MSS) of the ISS has been proposed as a signature for focal diseases, but its effectiveness has not been established yet. We show that the ISS distribution may function as a feature to characterize focal diseases even when its mean value MSS fails. The method proposed in this paper works even when data is non-stationary.  相似文献   
37.
以引进禾草柳枝稷为材料,在半干旱黄土丘陵区人工梯田设置20cm(L20)、40cm(L40)和60cm(L60)3种种植行距,比较研究了其光合生理参数日变化、地上部分生物量及土壤水分剖面分布特征,探讨其光合生理和水分利用特征与种植行距的关系。结果表明:(1)不同行距下,柳枝稷叶片净光合速率(Pn)日变化均呈双峰曲线,第一峰值均出现在10:00,第二峰值L40出现在14:00,L20和L60出现在16:00,具有明显的光合"午休"现象,且均由非气孔因素限制引起;柳枝稷叶片Pn日均值大小依次为:L60>L40>L20,且两两间差异显著。(2)柳枝稷叶片水分利用效率(WUE)日变化与Pn相似,分别在10:00和14:00达到峰值,日均值大小依次为:L60>L40>L20。(3)不同行距下,土壤体积含水量均随土层深度增加呈先增加后减少再增加的趋势,除0~50cm土层外,其它各土层土壤储水量均存在较大差异,0~380cm土层总土壤储水量表现为:L20>L40>L60。(4)柳枝稷地上生物量大小依次为:L20>L60>L40。研究发现,20cm行距的柳枝稷个体虽光合速率较低,但群体生物量和土壤储水量较高,所以柳枝稷在黄土丘陵区梯田的较优行距为20cm。  相似文献   
38.
Chromatin as an oxygen sensor and active player in the hypoxia response   总被引:1,自引:0,他引:1  
  相似文献   
39.
Abstract .1. The spatial patterning of nests in ten aggregations of a ground-nesting bee Halictus rubicundus (Christ) was examined using nearest-neighbour distance analysis.
2. Large scale aggregation was demonstrated and attributed to a preference for nesting in limited areas of the most suitable substrate in conjunction with natal site fidelity of nest-founding females.
3. Within patches of high nest density, there was a fine-scale regularity resulting from competition for sufficient substrate to maintain the structural integrity of the nest.
4. The appropriateness of four statistical tests is discussed with respect to analysing the spatial arrangement of nests in populations with both aggregated and regular components.  相似文献   
40.
Healthy seed tubers and seed tubers with gangrene or inoculated with Rhizoctonia solani to induce stem canker were planted 38 or 76 cm apart or alternately at 38 cm spacing in 2-row (1985) or 4-row (1986) plots at Rothamsted.
At 38 cm spacing, stem canker decreased yield by 5% and 8% respectively in 1985 and 1986 and gangrene by 5% and 14%, but usually by twice these amounts when seed was spaced at 76 cm. In all experiments, yields from plots with alternate healthy and inoculated seed (50% disease) were similar to yields from healthy seed, although within these mixed populations individual plant yields from healthy seed were larger and those from diseased seed were smaller than from plots of healthy or inoculated seed respectively. Samples in August showed a similar effect on fresh weight of foliage.
Disease usually decreased the number of stemdplant but in 1985 gangrene increased stem numbers and probably accounted for small amounts of compensatory growth from neighbouring healthy plants.  相似文献   
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