全文获取类型
收费全文 | 435篇 |
免费 | 73篇 |
国内免费 | 25篇 |
专业分类
林业 | 47篇 |
农学 | 45篇 |
基础科学 | 21篇 |
48篇 | |
综合类 | 70篇 |
农作物 | 27篇 |
水产渔业 | 152篇 |
畜牧兽医 | 98篇 |
园艺 | 9篇 |
植物保护 | 16篇 |
出版年
2024年 | 3篇 |
2023年 | 5篇 |
2022年 | 17篇 |
2021年 | 14篇 |
2020年 | 19篇 |
2019年 | 19篇 |
2018年 | 13篇 |
2017年 | 38篇 |
2016年 | 39篇 |
2015年 | 23篇 |
2014年 | 28篇 |
2013年 | 31篇 |
2012年 | 39篇 |
2011年 | 39篇 |
2010年 | 24篇 |
2009年 | 27篇 |
2008年 | 25篇 |
2007年 | 18篇 |
2006年 | 23篇 |
2005年 | 16篇 |
2004年 | 8篇 |
2003年 | 2篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1954年 | 1篇 |
1951年 | 2篇 |
1948年 | 1篇 |
1947年 | 1篇 |
排序方式: 共有533条查询结果,搜索用时 0 毫秒
521.
Hiroki Takakuwa Tetsu Yamashiro Mai Q. Le Lien S. Phuong Hiroichi Ozaki Ryota Tsunekuni Tatsufumi Usui Hiroshi Ito Tsuyoshi Yamaguchi Toshihiro Ito Toshiyuki Murase Etsuro Ono Koichi Otsuki 《Comparative immunology, microbiology and infectious diseases》2013
Due to concerns that wild birds could possibly spread H5N1 viruses, surveillance was conducted to monitor the types of avian influenza viruses circulating among the wild birds migrating to or inhabiting in northern Vietnam from 2006 to 2009. An H5N2 virus isolated from a Eurasian woodcock had a close phylogenetic relationship to H5 viruses recently isolated in South Korea and Japan, suggesting that H5N2 has been shared between Vietnam, South Korea, and Japan. An H9N2 virus isolated from a Chinese Hwamei was closely related to two H9N2 viruses that were isolated from humans in Hong Kong in 2009, suggesting that an H9N2 strain relevant to the human isolates had been transmitted to and maintained among the wild bird population in Vietnam and South China. The results support the idea that wild bird species play a significant role in the spread and maintenance of avian influenza and that this also occurs in Vietnam. 相似文献
522.
在总面积为8867m^2的3口池塘中进行了罗氏沼虾高产高效养殖试验。全年放养2批虾苗共110万尾,平均放苗123尾/m^2;共收获罗氏沼虾7641kg,平均8617.5kg/hm^2;共消耗饲料16500kg,饲料系数2.16;总产值311630元,平均产值351462.45元/hm^2,总利润165373元,平均利润186510.90元/hm^2,利润率为113.07%。本试验获得高产高效的结果证明了所采取的技术措施是可行的。 相似文献
523.
罗氏沼虾饲料蛋白质最适含量的研究 总被引:2,自引:1,他引:2
试验采用蛋白质梯度法,以酪蛋白、糊精、豆油、鱼油、纤维素粉以及复合维生素和矿物质等精制饲料为原料,设置13.28%~62.45%共10个蛋白质水平。试验用罗氏沼虾(Macrobrachium rosenbergii)的初始体重为1.55g,试验期间水温为28.5~31.2℃。以增重率为指标,用直线回归方法和抛物线回归方法求得罗氏沼虾饲料蛋白质的最适含量分别为37.02%和46.67%。如果综合考虑 相似文献
524.
Mai INOUE Atsuhiko HASEGAWA Yuta HOSOI Katsuaki SUGIURA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2016,78(2):347-350
The association between breed, gender and age and cardiovascular disorders in the insured dog population in
Japan was investigated, using multiple logistic regression analysis and data from 299,555 dogs insured between
April 2010 and March 2011. The overall annual prevalence of cardiovascular disorder diagnosis was 2.1%. Using
the Miniature Dachshund as the reference breed, Cavalier King Charles Spaniel had the highest odds of
cardiovascular disorder with a ratio of 16.2 (95% confidence interval: 14.4–18.2), followed by Maltese,
Pomeranian, Chihuahua and Shih Tzu. Male dogs had increased odds of 1.2 (1.1–1.3). The dogs had increased odds
of having cardiovascular disorder by 1.5 times as their age increased by one year. 相似文献
525.
养鳗池塘的浮游生物及其与鳗摄食关系的初步研究 总被引:3,自引:0,他引:3
报道了养鳗池塘的浮游生物种量及其与鳗摄食的关系,论述了水质良好的养鳗池塘浮游生物优势种,养鳗池和传统家鱼池生态学特点和养鳗池水质的有效调控措施。养鳗池塘的浮游生物群落结构与我国传统家鱼高产池塘的游浮生物群落结构区别较大。黑仔鳗塘的浮游植物则以硅藻类和绿藻类占优势,生物量分别占浮游植物总量的40%和37%。浮游动物则以轮虫和桡足类为主,枝角类的比例很少。浮游生物的丰度和群落结构对鳗的摄食有很大的影响 相似文献
526.
以裸沙地为对照,研究了海岸退化沙地不同植被恢复模式(天然次生林、木麻黄+潺槁木姜子混交林、木麻黄人工纯林)的土壤微生物量及其与土壤养分的关系。结果表明:裸沙地植被恢复后,不同植被恢复模式的土壤微生物量碳、氮、磷含量均明显提高(P<0.05),增幅分别为103.966%-491.166%、89.352%-335.087%、65.536%-85.896%,土壤微生物量碳、氮、磷占土壤有机碳、全氮、全磷的比例分别为1.543%-3.113%、1.733%-2.870%、0.964%-1.447%,自然恢复的天然次生林高于人工恢复的木麻黄纯林和混交林;土壤微生物量碳、氮、磷与土壤有机质、全氮、全磷、全钾呈极显著正相关(P<0.05),土壤微生物量碳、氮均与有机质、全氮具有较强的线性关系。 相似文献
527.
Takakuwa H Yamashiro T Le MQ Phuong LS Ozaki H Tsunekuni R Usui T Ito H Morimatsu M Tomioka Y Yamaguchi T Ito T Murase T Ono E Otsuki K 《Preventive veterinary medicine》2012,103(2-3):192-200
Repeated epizootics of highly pathogenic avian influenza (HPAI) virus subtype H5N1 were reported from 2003 to 2005 among poultry in Vietnam. More than 200 million birds were killed to control the spread of the disease. Human cases of H5N1 infection have been sporadically reported in an area where repeated H5N1 outbreaks among birds had occurred. Subtype H5N1 strains are established as endemic among poultry in Vietnam, however, insights into how avian influenza viruses including the H5N1 subtype are maintained in endemic areas is not clear. In order to determine the prevalence of different avian influenza viruses (AIVs), including H5N1 circulating among poultry in northern Vietnam, surveillance was conducted during the years 2006-2009. A subtype H5N1 strain was isolated from an apparently healthy duck reared on a farm in northern Vietnam in 2008 and was identified as an HPAI. Although only one H5N1 virus was isolated, it supports the view that healthy domestic ducks play a pivotal role in maintaining and transmitting H5N1 viruses which cause disease outbreaks in northern Vietnam. In addition, a total of 26 AIVs with low pathogenicity were isolated from poultry and phylogenetic analysis of all the eight gene segments revealed their diverse genetical backgrounds, implying that reassortments have occurred frequently among strains in northern Vietnam. It is, therefore, important to monitor the prevalence of influenza viruses among healthy poultry between epidemics in an area where AIVs are endemic. 相似文献
528.
529.
用叶面残留试验方法,测定了10种农田常用杀虫剂对莲草直胸跳甲幼虫的影响实验结果表明:敌敌畏、功夫、高效鱼藤氰、乐斯本、好年冬、米乐尔、速扑杀的LC50分别为21613、0634、2410、7433、9769、9349、9909mg/L,均小于其常用浓度,说明上述农药在常用浓度下对此叶甲幼虫影响较大;而乐果、杀虫双、巴丹的LC50分别为36517、1550、3837mg/L,均大于其常用浓度,说明上述农药在常用浓度下对跳甲幼虫影响较小 相似文献
530.
通过架设防虫网、人工养蝇、引蝇访花并选择不同天气类型观察苍蝇、蜂和其他种类昆虫在杧果(Manglfera indica)花穗上的活动情况,研究杧果传粉的主导因子、人工养蝇和引蝇访花对提高丰亡果授粉受精率的效果,以及在不同天气类型情况下温度对主要传粉昆虫苍蝇访花活动的影响。结果表明,丰亡果主要传粉媒介为昆虫,其中苍蝇在杧果传粉中起主要作用,其次为蜂。苍蝇在杧果花穗上的活动主要受温度影响,不同天气类型对苍蝇访花活动也有影响,在晴天天气条件下苍蝇在花穗上的活动时间和温度范围都较大。人工养蝇和引蝇访花可大幅度提高杧果受精发育果的比例。 相似文献