全文获取类型
收费全文 | 370篇 |
免费 | 37篇 |
出版年
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 3篇 |
2013年 | 17篇 |
2012年 | 15篇 |
2011年 | 11篇 |
2010年 | 7篇 |
2009年 | 13篇 |
2008年 | 10篇 |
2007年 | 11篇 |
2006年 | 13篇 |
2005年 | 13篇 |
2004年 | 9篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 6篇 |
1996年 | 3篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 14篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 14篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 17篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 4篇 |
1968年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有407条查询结果,搜索用时 531 毫秒
401.
402.
Benthic marine algal flora of the north shore of Prince Edward Island (Gulf of St. Lawrence), Canada
A seaweed community along 60 km of shoreline in the southern Gulf of St. Lawrence has been studied for 5 years. Because of severe ice action along the shores, the algal flora is largely restricted to subtidal levels, which are accessible only during the ice-free months, April to early December. A total of 52 Rhodophyta, 50 Phaeophyta, 19 Chlorophyta and 5 Cyanophyta was identified, mostly occurring between mean low water and 10 m depth. The normally intertidal dominants Focus vesiculosus L. and Chondrus crispus Stackh. flourish at depths of 0–2.5 m and 2.5–5 m, respectively. Chondrus and Furcellaria lumbricalis (Huds.) Lamour. co-dominate the algal benthos at 5–7.5 m, and F. lumbricalis becomes prevalent at 7.5–10 m. Phyllophora truncata (Pallas) A. Zin. and Phyllophora pseudoceranoides (Gmel.) Newr. & A. Tayl. are the main perennials at 10–15 m, and often at 15–20 m as well. Below 15 m, the flora diminishes markedly, and at 20–25 m consists chiefly of Agarum cribrosum (Mert.) Bory, crustose corallines and Polysiphonia urceolata (Lightf. ex Dillw.) Grev. Laminarians other than Chorda occur only as scattered plants or small patches and do not exceed 1 m length. The algal community is relatively undiversified and is especially deficient in green algae. Despite higher surface-water temperatures during summer, the flora is essentially a cold-water one as is indicated by both composition and low R/P and (R+C)/P ratios of 1.06 and 1.45, respectively. 相似文献
403.
Alaria grandifolia is recorded from Nova Scotia for the first time and is briefly compared with A. esculenta from this area. 相似文献
404.
405.
406.
G. J. McLachlan 《Biometrical journal. Biometrische Zeitschrift》1980,22(2):125-129
Some numerical results are presented for generalized ridge regression where the additive constants are based on the data. The adaptive estimator so obtained is compared with the least-squares estimator on the basis of mean square error (MSE). It is shown that the MSE of each component of the vector of ridge estimators may be as low as 47.1% of the variance of the corresponding component of the least squares vector or as high as 125.2%. 相似文献
407.
Hydrophobicity and amphiphilicity in protein structure 总被引:5,自引:0,他引:5