全文获取类型
收费全文 | 155篇 |
免费 | 3篇 |
出版年
2016年 | 3篇 |
2015年 | 2篇 |
2013年 | 3篇 |
2011年 | 5篇 |
2009年 | 2篇 |
2007年 | 4篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2002年 | 2篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1980年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1959年 | 4篇 |
1958年 | 5篇 |
1957年 | 4篇 |
1956年 | 7篇 |
1955年 | 3篇 |
1954年 | 8篇 |
1953年 | 2篇 |
1952年 | 5篇 |
1951年 | 10篇 |
1950年 | 7篇 |
1949年 | 4篇 |
1948年 | 5篇 |
1946年 | 3篇 |
排序方式: 共有158条查询结果,搜索用时 15 毫秒
81.
82.
There are presently two hypotheses concerning the modulationof avian vocalizations, one holding that resonance phenomenaplay an important role, the other that modulations are sourcegenerated. A wide variety of data tend to question the formerand support the latter. The Greenewalt model is examined in the light of recent findings,many of which support its major contentions and implications.On the other hand, the model seems to have certain weaknessesin describing the interactions of pressure, tension, and membranemovement, hence the linkage of AM and FM. Mathematical expressionsof these relationships are developed. They show that the amplitudeof oscillation will vary with the magnitude of the driving pressureperturbation and with the interaction of the frequencies ofthe perturbation and the resonant frequency of the membrane.This suggests an alternative mechanism for the AM-FM linkage. Caution is advised in the development of generalized models.Although all birds may exploit certain fundamental principles,the possibility remains that a variety of techniques may beemployed. A major difference between the techniques utilizedby oscines and non-oscines is especially probable. 相似文献
83.
84.
85.
The existing network of Protected Areas (PAs) in India is the major effort aimed at biodiversity conservation at the national level. The sustainability of PAs is heavily influenced by local people who are largely dependent on natural resources (fuel, fodder, minor forest products) for their livelihood. While all PAs are surrounded by historically resource-dependent communities, several of them have villages within their core areas, too. This has necessitated an alternative approach to natural resource management which aims to integrate the interests of conservation with those of the nearby resource dependent communities. The case of the Great Himalayan National Park illustrates and incorporates the lessons from Integrated Conservation and Development Projects (ICDPs) implemented elsewhere in the world. 相似文献
86.
87.
88.
89.
Aquaporins (AQP) 1, 2, 3 and 4 belong to the aquaporin water channel family and play an important role in urine concentration by reabsorption of water from renal tubule fluid. Renal AQPs have not been reported in the yak (Bos grunniens), which resides in the Qinghai Tibetan Plateau. We investigated AQPs 1?4 expressions in the kidneys of Yak using immunohistochemical staining. AQP1 was expressed mainly in the basolateral and apical membranes of the proximal tubules and descending thin limb of the loop of Henle. AQP2 was detected in the apical plasma membranes of collecting ducts and distal convoluted tubules. AQP3 was located in the proximal tubule, distal tubule and collecting ducts. AQP4 was located in the collecting ducts, distal straight tubule, glomerular capillaries and peritubular capillaries. The expression pattern of AQPs 1?4 in kidney of yak was different from other species, which possibly is related to kidney function in a high altitude environment. 相似文献
90.