全文获取类型
收费全文 | 314篇 |
免费 | 23篇 |
国内免费 | 47篇 |
专业分类
地球物理 | 30篇 |
地质学 | 24篇 |
海洋学 | 301篇 |
综合类 | 21篇 |
自然地理 | 8篇 |
出版年
2024年 | 2篇 |
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 12篇 |
2015年 | 7篇 |
2014年 | 20篇 |
2013年 | 27篇 |
2012年 | 7篇 |
2011年 | 10篇 |
2010年 | 12篇 |
2009年 | 17篇 |
2008年 | 15篇 |
2007年 | 17篇 |
2006年 | 35篇 |
2005年 | 19篇 |
2004年 | 16篇 |
2003年 | 18篇 |
2002年 | 12篇 |
2001年 | 13篇 |
2000年 | 8篇 |
1999年 | 15篇 |
1998年 | 11篇 |
1997年 | 29篇 |
1996年 | 6篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有384条查询结果,搜索用时 15 毫秒
1.
2.
3.
鱼类没有消化的食物通过粪便而排出体外.没有消化的食物、黏液、消化道脱落细胞、代谢酶以及细菌等就组成了鱼类的粪便.排粪后所保留的食物能可以通过吸收率来估算,其计算式为:A=C-FC/C×100%,式中A(吸收率)以百分数表示;C(摄食量)等于摄入的食物质量乘以食物比能值;F(粪便排出量)等于排出的粪便质量乘以粪便比能值.吸收率在营养学上又称为消化率.粪便比能值的测定在计算吸收率时是非常必要的,但在以往对鱼类吸收率的研究[1~6]中,由于粪便收集的困难及粪便的样品量通常很少,均没有对不同条件下鱼类所排出粪便的比能值进行单独的测定. 相似文献
4.
5.
6.
CHEN Yan KE Caihuan ZHOU Shiqiang LI FuxueDepartment of Oceanography Key Laboratory for Marine Environmental Science of the Ministry of Education Xiamen University Xiamen China 《海洋学报(英文版)》2004,(3)
The development of embryos and larvae of Babylonia formosae habei living along the southeast coast of China is observed under laboratory conditions. The egg masses are laid by females on hard substrate at night and each capsule contains 100-500 eggs. Each egg is 250-280 mm in diameter. The first two cleavages of the embryo are meridional and equal, and a polar lobe is produced. Larval kidney, which only consists of a single cell, appears during the gastrula stage on each side of the embryo. The right tentacle develops prior to the left one. At 25-27℃, an intracapsulate veliger stage is reached about 4.5 d after deposition. The larvae hatch on the fifth day as swimming veligers with a shell length of 360 -500 mm. The newly hatched larva can ingest suspended algal cells from the water column and remains in the pelagic stage for 8-10 d. The newly settled juveniles are 900-1 200 mm in shell length. 相似文献
7.
Friedland Kevin D.; Chaput Gerald; MacLean Julian C. 《ICES Journal of Marine Science》2005,62(7):1338-1349
8.
9.
Recent events concerning Atlantic salmon escapees in the Pacific 总被引:1,自引:0,他引:1
10.
The development of embryos and larvae of Babyloniaformosae habei living along the southeast coast of China is observed under laboratory conditions. The egg masses are laid by females on hard substrate at night and each capsule contains 100-500 eggs. Each egg is 250-280 mm in diameter. The fast two cleavages of the embryo are meridional and equal, and a polar lobe is produced. Larval kidney, which only consists of a single cell, appears during the gastrula stage on each side of the embryo. The right tentacle develops prior to the left one. At 25-27 ℃, an intracapsulate veliger stage is reached about 4.5 d after deposition. The larvae hatch on the fifth day as swimming veligers with a shell length of 360 -500 mm. The newly hatched larva can ingest suspended algal cells from the water column and remains in the pelagic stage for 8-10 d. The newly settled juveniles are 900-1 200 mm in shell length. 相似文献