全文获取类型
收费全文 | 100篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
102篇 |
出版年
2022年 | 1篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 8篇 |
2008年 | 5篇 |
2007年 | 12篇 |
2006年 | 3篇 |
2005年 | 1篇 |
2004年 | 7篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 19篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有102条查询结果,搜索用时 15 毫秒
101.
P. E. Hertz 《Oecologia》1992,90(1):127-136
Summary The field thermal biology of sympatric Anolis cooki and A. cristatellus were evaluated in January and in August in desert scrub forest at Playa de Tamarindo near Guanica, Puerto Rico. Data on randomly positioned copper models of lizards, each equipped with a built-in thermocouple, established null hypotheses about basking frequency and operative temperatures (T
e) against which the behavior and body temperatures (T
b) of live lizards were evaluated. Both species exhibited non-random hourly basking rates (more marked in cristatellus than in cooki), and cristatellus was virtually inactive during the warm mid-day hours. The relationship between lizards' T
b and randomly sampled T
e differed between the species: cristatellus's mean T
b was 2° to 3° C lower than randomly sampled mean T
e in both months, whereas cooki's mean T
b was slightly higher than mean T
e in January and slightly lower in August. Although cooki's mean T
b was higher than that of cristatellus in both months, the T
b's of the two species overlapped substantially over an annual cycle. Given the similarities in their field active T
b and the low thermal heterogeneity among microsites at Playa de Tamarindo, these species appear not to partition the thermal environment there in a coarse-grained way. Instead, the relatively small differences in their field active T
b probably result from small differences in their use of similar microhabitats within their mutually exclusive territories. Thermal resource partitioning by territorial animals is unlikely unless thermal heterogeneity is coarse-grained in relation to territory size. 相似文献
102.
Jenny M. Dauer Jon Chorover Oliver A. Chadwick Jacek Oleksyn Mark G. Tjoelker Sarah E. Hobbie Peter B. Reich David M. Eissenstat 《Biogeochemistry》2007,86(2):175-187
Four-fold variation in leaf-litter Ca concentration among 14 tree species growing in a common garden in central Poland was
linked to variation in soil pH, exchangeable Ca, soil base saturation, forest floor turnover rates, and earthworm abundance.
Given the potential importance of tissue Ca to biogeochemical processes, in this study we investigated potential controls
on leaf Ca concentrations using studies of both laboratory seedlings and 30-year-old trees in the field. We first assessed
whether species differences in Ca concentration of green leaves and leaf litter were due to differences in Ca uptake, plant
growth, or Ca translocation to different organs, by measuring seedlings of 6 of the 14 species grown under controlled conditions
of varying Ca supply. We also investigated whether trees species with high Ca concentrations in green leaves and leaf litter
access soil Ca to a greater extent than low-Ca species by growing more fine roots in high-Ca soil horizons. Root distribution
in the field was determined in all 14 tree species by profile wall mapping and soil sampling of excavated pits. There was
no correlation between horizon root count density (number of roots m−2) and exchangeable soil Ca, nor was there a correlation of stand-level leaf litter Ca with density of roots 45–100 cm deep
in the soil, suggesting that a deeper root distribution does not result in greater Ca acquisition among these species. Variation
among species in leaf Ca concentration of greenhouse seedlings was positively correlated with leaf Ca concentrations of mature
trees, indicating that the same ranking in leaf Ca among species existed under controlled Ca supply. Species also differed
in seedling growth response to Ca supply. Tilia, the species with the highest leaf Ca in the field, generated only 10% as much biomass and height at low relative to high
Ca supply, whereas the other species exhibited no significant differences. Species exhibited differences in (i) partitioning
of whole plant Ca and biomass to leaf, stem and root organs and (ii) the pattern of such partitioning between high and low
Ca treatments. Our data support the hypothesis that although soil Ca supply can contribute to variation among trees in leaf
and litter Ca concentration, innate physiological differences among species also can be a major cause for species variation. 相似文献