全文获取类型
收费全文 | 366篇 |
免费 | 12篇 |
国内免费 | 7篇 |
专业分类
林业 | 20篇 |
农学 | 16篇 |
基础科学 | 1篇 |
38篇 | |
综合类 | 70篇 |
农作物 | 22篇 |
水产渔业 | 32篇 |
畜牧兽医 | 157篇 |
园艺 | 7篇 |
植物保护 | 22篇 |
出版年
2024年 | 2篇 |
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 12篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 9篇 |
2015年 | 11篇 |
2014年 | 9篇 |
2013年 | 20篇 |
2012年 | 15篇 |
2011年 | 14篇 |
2010年 | 19篇 |
2009年 | 22篇 |
2008年 | 20篇 |
2007年 | 19篇 |
2006年 | 9篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 14篇 |
2002年 | 9篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 15篇 |
1984年 | 6篇 |
1983年 | 17篇 |
1982年 | 2篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 24篇 |
1978年 | 4篇 |
1977年 | 1篇 |
排序方式: 共有385条查询结果,搜索用时 156 毫秒
381.
Laura Prosdocimi Natalia S. Teryda Gabriela S. Navarro Raymond R. Carthy 《水产资源保护:海洋与淡水生态系统》2021,31(4):830-840
- Fisheries bycatch of non-target species in the commercial fleet is a major source of anthropogenic injury and mortality for sea turtles and marine megafauna.
- The Río de la Plata maritime front (RLPMF) and its adjacent international waters – comprising part of the Argentine and Uruguayan exclusive economic zones, is a highly important fishing ground in the south-western Atlantic Ocean as well as feeding and development grounds for sea turtles.
- This paper analyses the distribution of the bottom and pelagic trawling fishery within the RLPMF using information from Vessel Satellite Monitoring System. With this information, areas of highest trawling intensity were defined and further evaluated their overlap with sea turtle habitat-use areas from available sea turtle satellite tracking information.
- Results besides identifying high-susceptibility areas for sea turtle bycatch by the commercial trawler fleet along the RLPMF, provide predictive tools to identify vulnerable areas to interaction of sea turtles and the commercial fishing fleet.
- Implementation of bycatch mitigation measures, such as reduced fishing effort areas by the Argentine and Uruguayan fisheries management agencies has the potential to benefit the fisheries as well as marine megafauna. Furthermore, there is a need for additional research on the impact that this fleet can have on sea turtles present in the area.
382.
以无刺卡因、巴厘这两类品种的菠萝叶纤维为原料,对老叶和嫩叶所提取的纤维进行不同部位的纤维细度测定,结果表明:无刺卡因类菠萝叶老叶提取的纤维长度达到80~100 cm,尖部和根部的纤维平均细度分别为14.40、18.53 dtex,嫩叶提取纤维的长度一般在50~70 cm,纤维根部和尖部的纤维平均细度分别为13.27、14.77 dtex;巴厘类菠萝叶提取的纤维长度达到70~90 cm,尖部和根部的纤维平均细度分别为14.13、18.50 dtex,嫩叶提取纤维的长度一般在45~65 cm,纤维根部和尖部的纤维平均细度分别为13.09、15.03 dtex。经方差分析,卡因类和巴厘类菠萝叶老叶根部与尖部纤维细度存在显著差异(p<0.05)。 相似文献
383.
Sean C Anderson Joanna Mills Flemming Reg Watson Heike K Lotze 《Fish and Fisheries》2011,12(3):317-339
In recent decades, invertebrate fisheries have expanded in catch and value worldwide. One increasingly harvested group is sea cucumbers (class Holothuroidea), which are highly valued in Asia and sold as trepang or bêche‐de‐mer. We compiled global landings, economic data, and country‐specific assessment and management reports to synthesize global trends in sea cucumber fisheries, evaluate potential drivers, and test for local and global serial exploitation patterns. Although some sea cucumber fisheries have existed for centuries, catch trends of most individual fisheries followed boom‐and‐bust patterns since the 1950s, declining nearly as quickly as they expanded. New fisheries expanded five to six times faster in 1990 compared to 1960 and at an increasing distance from Asia, encompassing a global fishery by the 1990s. Global sea cucumber production was correlated to the Japanese yen at a leading lag. Regional assessments revealed that population declines from overfishing occurred in 81% of sea cucumber fisheries, average harvested body size declined in 35%, harvesters moved from near‐ to off‐shore regions in 51% and from high‐ to low‐value species in 76%. Thirty‐eight per cent of sea cucumber fisheries remained unregulated, and illegal catches were of concern in half. Our results suggest that development patterns of sea cucumber fisheries are largely predictable, often unsustainable and frequently too rapid for effective management responses. We discuss potential ecosystem and human community consequences and urge for better monitoring and reporting of catch and abundance, proper scientific stock assessment and consideration of international trade regulations to ensure long‐term and sustainable harvesting of sea cucumbers worldwide. 相似文献
384.
分离得到一株对黄瓜菌核病菌Sclerotinia sclerotiorum(Lib.)de Bary有拮抗作用的枯草芽孢杆菌G8,其无菌发酵液经硫酸铵沉淀得广谱抗菌粗蛋白。为明确枯草芽孢杆菌G8的理化性质,研究了温度、pH变化、UV照射、有机溶剂、蛋白酶和保存时间对抗菌蛋白稳定性的影响。结果表明:此粗蛋白耐酸,在pH值1~10范围内均有抑菌活性,将其pH值调为1.0作用16h后保持原有活性的69.2%;对温度有较高的稳定性,抗菌蛋白经100℃处理60min保持原有活性的80.8%;对蛋白酶K和有机溶剂不敏感;抗菌粗蛋白抑菌活性持久,在常温下120天保持原有活性的71.54%。初步研究了抗菌粗蛋白对黄瓜菌核病菌的抑制作用。结果显示,病菌菌丝消融、原生质渗漏、菌丝细胞泡囊化,并抑制病菌菌核萌发。 相似文献
385.