全文获取类型
收费全文 | 256篇 |
免费 | 23篇 |
出版年
2021年 | 3篇 |
2016年 | 6篇 |
2015年 | 8篇 |
2014年 | 7篇 |
2013年 | 16篇 |
2012年 | 6篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2008年 | 6篇 |
2007年 | 8篇 |
2006年 | 12篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 7篇 |
1998年 | 6篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1992年 | 3篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1987年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1978年 | 3篇 |
1973年 | 5篇 |
1971年 | 5篇 |
1970年 | 4篇 |
1969年 | 7篇 |
1968年 | 5篇 |
1966年 | 2篇 |
1964年 | 3篇 |
1963年 | 5篇 |
1962年 | 4篇 |
1961年 | 5篇 |
1960年 | 3篇 |
1959年 | 3篇 |
1958年 | 5篇 |
1957年 | 7篇 |
1956年 | 4篇 |
1955年 | 2篇 |
1954年 | 2篇 |
1953年 | 3篇 |
1951年 | 2篇 |
1950年 | 4篇 |
1949年 | 2篇 |
1944年 | 2篇 |
1936年 | 2篇 |
排序方式: 共有279条查询结果,搜索用时 15 毫秒
141.
142.
143.
B. L. Barthel S. J. Cooke J. H. Svec C. D. Suski C. M. Bunt F. J. S. Phelan D. P. Philipp 《Journal of fish biology》2008,73(4):829-852
Annual reproductive surveys monitored nesting location, reproductive success and the age and size of individually tagged male smallmouth bass Micropterus dolomieu that reproduced in Millers Lake, a 45 ha widening of the Mississippi River, Ontario, and in a 1·5 km pool and riffle section of the river directly upstream. The vast majority of males displayed fidelity to either the river or the lake as reproductive habitat throughout their lifetimes. Nearly, half of the males that reproduced in successive years exhibited strong nest‐site fidelity by nesting within 20 m of their previous year’s nest site. In most years, when compared to those in the lake, reproductive males in the river differed significantly in reproductive characteristics including age and size at maturation and nesting success rates. A 3 year telemetry project identified two distinct habitat use patterns: lake‐resident fish remained in the lake throughout the year and potamodromous individuals migrated from the lake to upriver spawning habitat in the spring and then returned to the lake prior to the onset of winter. Integration of habitat use and reproductive data suggests that there are significant differences in the life‐history strategies of fish that reproduce in the river v. the lake. 相似文献
144.
145.
146.
Ultrastructural study of previtellogenic oocytes found in cystlike clusters scattered throughout the length of the bilobed ovary of the hermit crab Coenobita clypeatus shows a high nuclear:cytoplasm ratio. Large, round nuclei containing synaptinemal complexes serve as good temporal markers for identification of previtellogenic oocytes. The cytoplasm contains many smooth-membraned vesicles filled with granules and probably of nuclear origin. In addition to its complement of Golgi complexes, endoplasmic reticulum, mitochondria, and free ribosomes, the cytoplasm also contains stacks of annulate lamellae, a feature not previously described for decapod oocytes. Typically, the previtellogenic oocyte with its accumulation of ribosomes has the appearance of a nonsynthetic cell preparing to go through a metabolic transition. 相似文献
147.
148.
149.
Christopher M. Bunt Nicholas E. Mandrak Dana C. Eddy Stephanie A. Choo-Wing Thomas G. Heiman Emily Taylor 《Environmental Biology of Fishes》2013,96(10-11):1281-1287
Black Redhorse (Moxostoma duquesnei) larval and juvenile habitat was characterized in the Grand River, Ontario from June to September 2007–2012. Similar to adult Black Redhorse and their congeners, larval Black Redhorse were most likely to be located in clean, clear, stable runs with low to moderate flow, over pebble, gravel and cobble substrate, mixed with sand. Areas (n?=?22) where 0+ Black Redhorse were observed and collected were 1.4?±?0.2 m from shore, with a mean water temperature of 22.0?±?0.5 °C, mean depth of 0.20?±?0.02 m and mean water velocity of 0.12?±?0.05 m/s. Larval and juvenile Black Redhorse occupied riffles, runs, pools and backwater areas; however, there was a strong preference for runs. Juvenile Black Redhorse moved upstream in the early evening and at night to overwintering areas in the Grand River in November when water temperature approached 5 °C. The persistence of Black Redhorse populations in the Grand River may be related to the presence of groundwater, which provides refuge from extreme temperature and poor water quality during the summer. 相似文献
150.
Patricia Akweongo Maxwell A. Dalaba Mary H. Hayden Timothy Awine Gertrude N. Nyaaba Dominic Anaseba Abraham Hodgson Abdulai A. Forgor Rajul Pandya 《PloS one》2013,8(11)