全文获取类型
收费全文 | 7701篇 |
免费 | 50篇 |
国内免费 | 14篇 |
专业分类
林业 | 750篇 |
农学 | 239篇 |
基础科学 | 49篇 |
976篇 | |
综合类 | 341篇 |
农作物 | 519篇 |
水产渔业 | 481篇 |
畜牧兽医 | 3673篇 |
园艺 | 201篇 |
植物保护 | 536篇 |
出版年
2022年 | 14篇 |
2019年 | 18篇 |
2018年 | 122篇 |
2017年 | 189篇 |
2016年 | 174篇 |
2015年 | 244篇 |
2014年 | 214篇 |
2013年 | 181篇 |
2012年 | 462篇 |
2011年 | 326篇 |
2010年 | 121篇 |
2009年 | 81篇 |
2008年 | 87篇 |
2007年 | 56篇 |
2006年 | 53篇 |
2005年 | 793篇 |
2004年 | 659篇 |
2003年 | 451篇 |
2002年 | 120篇 |
2001年 | 132篇 |
2000年 | 33篇 |
1999年 | 146篇 |
1992年 | 117篇 |
1991年 | 145篇 |
1990年 | 168篇 |
1989年 | 147篇 |
1988年 | 172篇 |
1987年 | 113篇 |
1986年 | 143篇 |
1985年 | 117篇 |
1984年 | 91篇 |
1983年 | 81篇 |
1982年 | 33篇 |
1981年 | 17篇 |
1980年 | 23篇 |
1979年 | 133篇 |
1978年 | 96篇 |
1977年 | 91篇 |
1976年 | 77篇 |
1975年 | 137篇 |
1974年 | 129篇 |
1973年 | 116篇 |
1972年 | 138篇 |
1971年 | 118篇 |
1970年 | 88篇 |
1969年 | 102篇 |
1968年 | 113篇 |
1967年 | 125篇 |
1966年 | 102篇 |
1965年 | 70篇 |
排序方式: 共有7765条查询结果,搜索用时 15 毫秒
1.
大豆抗菌核病的全基因组关联研究 总被引:2,自引:0,他引:2
找到大豆与抗菌核病强关联的候选位点或候选基因,为抗病基因克隆和抗病分子标记开发提供借鉴,服务大豆抗菌核病育种。对126个加拿大大豆品种的基因组DNA用ApekⅠ酶消化后Illumina Hiseq2000平台测序进行基因分型,供试的126个材料用棉垫接种核盘菌菌丝体进行表型鉴定。采用Structure 2.3.4、SPSS 20.0、TASSEL 5.0和PLINKv 1.07软件分别模拟群体遗传结构、二元主成分分析、邻接法聚类,进行SNP-phenotype和Haplotype-phenotype的关联分析(只考虑加性效应)。最小等位基因频率0.01过滤,得到30 125个SNPs。主成分及群体结构聚类结果中度一致,将126个供试材料划分为2个组群,Kappa聚类一致度检验K=0.44。邻接法(The neighbor-joining algorithm,NJ)聚为3个组群。α≤0.05时,在单个SNP-phenotype的关联研究中,最强关联在3号染色体物理位置34387780、34387823和34387841处(P值都为8.669E-7),可分别解释表型变异的17.80%,其次在20,1,4,17号染色体上。Haplotype-phenotype的关联分析中,最强关联在17号染色体物理位置5575883/5647814/5648648/5734897处(P值为1.038E-6),可解释表型变异的17.56%。200 kb范围内,3号染色体上的候选基因有Glma.03g129100、Glma.03g129200、Glma.03g129300、Glma.03g129500、Glma.03g129800、Glma.03g129900。17号染色体上为Glma.17g071300、Glma.17g072200、Glma.17g073300。 相似文献
2.
3.
Shinya Kasajima Chidori Katagiri Toshikazu Morishita Tatsuro Suzuki Yuji Mukasa 《Plant Production Science》2017,20(4):384-388
Common buckwheat is a self-incompatible, insect-pollinated allogamous plant. This study examined growth and yield of the common buckwheat self-compatible and hybrid lines pollinated with and without flies. Self-compatible ‘IH3’, hybrid ‘IP2/IH3’, and standard self-incompatible ‘Kitawasesoba’ were used in field and pot experiments. Self-compatibility of ‘IH3’ was shown to be of high purity. Approximately 10% segregation of pin plants from ‘IP2/IH3’ was observed. The harvest index of ‘Kitawasesoba’ pollinated without flies was considerably lower than that pollinated with flies in both field and pot experiments. The harvest index values of ‘IH3’ and ‘IP2/IH3’ were hardly affected by the presence or absence of flies. The morphological traits of ‘IH3’ were significantly lower than those of the other two genotypes. Large differences in these traits between ‘IP2/IH3’ and ‘Kitawasesoba’ were not observed in either the field or pot experiments. The seed yield of ‘Kitawasesoba’ pollinated without flies tended to be lower than that pollinated with flies. The seed yield of ‘IP2/IH3’ tended to be higher than that of ‘IH3’. The hybrid line ‘IP2/IH3’ showed a high fertilization rate, which was nearly as high as that of ‘IH3’. Rate of fertilization and percentage of ripe seeds were higher in ‘IH3’ and ‘IP2/IH3’, wherein they were hardly affected by the presence or absence of flies, than in ‘Kitawasesoba’. The ‘IP2/IH3’ hybrid line will be useful for understanding the stable high-yielding ability of self-compatibility common buckwheat. 相似文献
4.
Filipe?Selau?CarlosEmail author Bruno?Loss?dos?Santos Robson?Andreazza Marino?José?Tedesco Lawrence?Morris Flávio?Anastácio?de?Oliveira Camargo 《Paddy and Water Environment》2017,15(1):133-144
Treated industrial effluents have high levels of nutrients and dissolved organic matter. The irrigation of rice by flooding can increase nutrient uptake and grain yield. Therefore, this study evaluated the nutrient contents in the shoots and grain of the rice crop and also the chemical of the soil after irrigation of the crop with leachate of the treated industrial effluent. A greenhouse experiment was conducted using pots filled with 20 kg of soil in a randomized block design with three replications. The treatments consisted of control (irrigation with distilled water) and four concentrations of the leachate (25, 50, 75, and 100 %) for irrigation. At the end of the experiment, the nutrient contents in tissues of rice plants, sterility of spikelets, and grain mass were evaluated. Results showed that irrigation with the leachate at 25 % content increased the macro- and micronutrients’ concentrations in the shoot biomass and grain, except for potassium and iron. Irrigation with the industrial leachate decreased tillering and grain yield; however, it increased chlorophyll content, sterility of spikelets, and sodium intake at this leachate concentration. The potassium and sodium levels and the electrical conductivity values of soils irrigated with treated industrial leachate were increased. The use of the treated leachate from industrial effluents is an alternative that reuses the nutritional load, but the volume of leachate should be limited and monitored to prevent the sodicity in the soil and problemsdue to eutrophication. 相似文献
5.
水稻机械化插秧能够大幅度提高劳动生产率,减轻劳动强度,降低生产成本,达到增产增收的效果。试验结果表明:水稻机插栽培有效穗数多,有利于形成较为合理的群体结构,从而穗粒数较多,结实率提高,产量高,增产效果明显。 相似文献
6.
7.
8.
Fisheries Science - The changes in volatile compounds of living oysters Crassostrea gigas with shells under air-exposed storage for 7 days at 5 and 20 °C were investigated... 相似文献
9.
Estelle C.C. ?gren Jan Johansson Jenny Fr?ssling Helene Wahlstr?m Ulf Emanuelson Susanna Sternberg-Lewerin 《Acta veterinaria Scandinavica》2015,57(1)
Background
The Swedish control program for salmonella includes restrictions and on-farm control measures when salmonella is detected in a herd. Required control measures are subsidised by the government. This provides an opportunity to study costs for on-farm salmonella control. The aim of this study was to describe the costs for on-farm salmonella control in Swedish cattle herds and to investigate the effects of herd factors on these costs in dairy herds.Results
During the 15 years studied there had been a total of 124 restriction periods in 118 cattle herds; 89 dairy herds, 28 specialised fattening herds and three suckler herds. The average costs per herd for on-farm salmonella control was 4.60 million SEK with a median of 1.06 million SEK corresponding to approximately 490 000 and 110 000 EUR. The range was 0.01 to 41 million SEK corresponding to 1080 EUR to 4.44 million EUR per farm. The costs cover measures required in herd-specific control plans, generally measures improving herd hygiene. A mixed linear model was used to investigate associations between herd factors and costs for on-farm salmonella control in dairy herds. Herd size and length of the restriction period were both significantly associated with costs for on-farm control of salmonella with larger herds and longer periods of restrictions leading to higher costs. Serotype detected and administrative changes in the Swedish Board of Agriculture aiming at reducing costs were not associated with costs for on-farm salmonella control.Conclusions
On-farm control of salmonella in Swedish cattle herds incurred high costs but the costs also varied largely between herds. Larger herds and longer restriction periods increased the costs for on-farm control of salmonella in Swedish dairy herds. This causes concern for future costs for the Swedish salmonella control program as herd sizes are increasing. 相似文献10.