收费全文 | 3386篇 |
免费 | 306篇 |
国内免费 | 60篇 |
林业 | 307篇 |
农学 | 152篇 |
基础科学 | 40篇 |
692篇 | |
综合类 | 159篇 |
农作物 | 236篇 |
水产渔业 | 533篇 |
畜牧兽医 | 1201篇 |
园艺 | 109篇 |
植物保护 | 323篇 |
2024年 | 8篇 |
2023年 | 50篇 |
2022年 | 73篇 |
2021年 | 151篇 |
2020年 | 146篇 |
2019年 | 171篇 |
2018年 | 198篇 |
2017年 | 192篇 |
2016年 | 192篇 |
2015年 | 130篇 |
2014年 | 168篇 |
2013年 | 220篇 |
2012年 | 253篇 |
2011年 | 269篇 |
2010年 | 173篇 |
2009年 | 146篇 |
2008年 | 192篇 |
2007年 | 158篇 |
2006年 | 137篇 |
2005年 | 105篇 |
2004年 | 85篇 |
2003年 | 100篇 |
2002年 | 125篇 |
2001年 | 96篇 |
2000年 | 65篇 |
1999年 | 33篇 |
1998年 | 11篇 |
1997年 | 17篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 4篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1970年 | 1篇 |
1965年 | 1篇 |
1934年 | 2篇 |
1930年 | 1篇 |
1926年 | 1篇 |
1925年 | 1篇 |
![点击此处可从《Journal of the World Aquaculture Society》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Context
The use of native species in ecological restoration is highly recommended but, in practice, it is often impaired by knowledge gaps in the germination ecology of suitable species.Aims
This study aimed to assess the role of storage conditions and seed source on the germination of three Mediterranean shrub species with contrasting types of dormancy.Methods
Ripe fruits were harvested at two or three distant locations in mainland Portugal. Seeds were subjected to three treatments consisting in different storage conditions: cold storage at low and high moisture conditions, plus a control. Five replicates of up to 30 seeds were placed under constant temperature conditions and germination was monitored weekly during 14 weeks.Results
The effect of cold storage at high moisture on germination differed between the three species and seed source played a significant role in the germination of all three species. In the case of the species with dormancy, the observed differences in germination could reflect changes in the species’ dormancy degree or sensitivity to dormancy breaking factors across their geographical range. In the case of Pistacia lentiscus (no dormancy), the results suggested a possible adaptation of the northern seed source to high moisture conditions.Conclusions
The observed differences between species agreed well with their dormancy types, and the seed source-related differences could be adaptive features, as they seemed related with local climate conditions. 相似文献2. A total of 200 Ross broiler breeder hens at 42 weeks of age were randomly divided into two groups: MS or control. Hens in the MS were fed 2 mg/hen/d CORT for 14 d. Eggs (648 and 635 eggs for MS and control, respectively) were collected from d 3 to 14 of dietary CORT supplementation and incubated. Weights of embryo, chicks and organs and body composition were determined during incubation and at hatch. Biochemical blood parameters were measured at internal pipping stage and day of hatch. Hatching performance and embryonic mortalities were recorded.
3. Hens fed a diet supplemented with CORT had lighter body weight and produced less eggs at the end of the 14-d treatment period. Although MS embryos were heavier than control from 12 to 18 d of incubation, chick weight was similar at the day of hatch. Lower relative weights for yolk sac and bursa were observed at 12 d of incubation for MS chicks compared to control. Chicks from both groups had similar body content in spite of higher fat content of MS embryos on d 18 of incubation.
4. MS had no effect on the duration of incubation or hatching performance but increased mortality at the pipping stage.
5. The results suggest that hormone-mediated MS might affect embryonic development during incubation without adverse effect on chick weight and body composition. 相似文献