全文获取类型
收费全文 | 409篇 |
免费 | 35篇 |
国内免费 | 60篇 |
专业分类
林业 | 8篇 |
农学 | 32篇 |
26篇 | |
综合类 | 139篇 |
农作物 | 10篇 |
水产渔业 | 117篇 |
畜牧兽医 | 144篇 |
园艺 | 6篇 |
植物保护 | 22篇 |
出版年
2024年 | 3篇 |
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 14篇 |
2020年 | 13篇 |
2019年 | 12篇 |
2018年 | 8篇 |
2017年 | 18篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 13篇 |
2013年 | 11篇 |
2012年 | 18篇 |
2011年 | 42篇 |
2010年 | 45篇 |
2009年 | 40篇 |
2008年 | 43篇 |
2007年 | 42篇 |
2006年 | 36篇 |
2005年 | 22篇 |
2004年 | 20篇 |
2003年 | 13篇 |
2002年 | 12篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有504条查询结果,搜索用时 15 毫秒
131.
Amani S.Y. Al-Zaidan Abrar Akbar Hussain Bahbahani Salim Y. Al-Mohanna Biju Kolattukudy Varun Balakrishna 《水产资源保护:海洋与淡水生态系统》2021,31(4):802-817
- To our knowledge, this is the first inclusive assessment of the status of Sparidae fisheries in the territorial waters of Kuwait, integrating information on catch trends, consumer preferences, recreational fishing behaviour, and molecular based identification of fish species by DNA barcoding
- Fisheries landing data were obtained from the official fisheries bulletin released by the Kuwait Central Statistical Bureau. Surveys were conducted to assess consumer preferences on seabream species, landed seabream species, and the behaviour of recreational anglers towards seabream species. DNA barcodes were generated to authenticate commercial seabream using the mitochondrial cytochrome c oxidase subunit I (COXI) gene and then compared with GenBank sequence entries; these sequences were then used to construct a neighbour-joining (NJ) phylogenetic tree.
- Yellowfin seabream Acanthopagrus latus was the prime and most favoured commercial seabream species (45%), followed by Sparidentex hasta, which was the top-rated secondary, unassessed seabream species. Approximately 54% of households conduct recreational fishing more than twice a month, and most (77%) primarily target S. hasta and Ac. latus. Consumer demand for secondary seabreams, which were not assessed and are listed in the bulletin under the category ‘others’, was evident.
- The NJ phylogenetic tree revealed that Arabian Gulf seabreams, including those of Kuwait, are genetically different from their counterparts inhabiting neighbouring waters.
- The data presented here highlight the urgency to modify the existing fisheries list using accurate identification tools, such as DNA barcoding, for the sustainable and conservation-oriented management of local fisheries, which are in decline.
132.
海南三亚斑节对虾野生种群mtDNA 16S rRNA基因和控制区序列的多态性 总被引:1,自引:0,他引:1
采用聚合酶链式反应(PCR)技术对海南三亚野生斑节对虾(Penaeus monodon)20个个体的mtDNA 16S rRNA基因和控制区序列进行扩增,PCR产物经纯化后进行测序,得到16S rRNA基因的495 bp的核苷酸序列和控制区序列470 bp的核苷酸片段。用Clustal X软件对16S rRNA和控制区序列进行了比对,通过ARLEQUIN 2000软件对所得线粒体16S rRNA基因片段和控制区序列进行了比较分析。16S rRNA序列检测出17个多态位点,8种单倍型;控制区序列检测出100个多态位点,17种单倍型。该种群16S rRNA序列基因多样度(H)和碱基多样度(π)分别为0.700和0.0045;控制区序列的H和π分别为0.984和0.0480。研究结果表明:16S rRNA序列不适应斑节对虾的种群遗传多样性分析;控制区序列适应斑节对虾种群遗传多样性研究。 相似文献
133.
鲤属鱼类mtDNA控制区(D—环区)序列的变异性分析 总被引:17,自引:0,他引:17
采用PCR-测序技术对我国鲤属7个种,亚种和2个品种共62个个体(其中鲤的样品包括采自长江,黄河,松花江三个水系的共4个种群)。进行了mtDNA控制区(D-环区)始自3‘端共459bp碱基的序列测定。发现其D-环区3‘端至中央保守区之间不似其他鱼类和哺乳类是一个单一的高变区,而是在其内部还插有一段长约110bp的保守区,这很可能是鲤属鱼类mtDNAD-环区自身的一个特点。 相似文献
134.
本研究通过对玉米螟赤眼蜂Trichogramma ostriniae不同地理种群的线粒体DNA COⅠ、COⅡ和Cytb基因进行序列分析,研究了我国玉米螟赤眼蜂不同地理种群的遗传分化程度.结果发现,玉米螟赤眼蜂群体内线粒体基因具有丰富的遗传多态性,且各地理种群之间已产生不同程度的遗传分化.中性检测结果表明,玉米螟赤眼蜂进化遵循中性模型,且在过去呈现种群扩张趋势.玉米螟赤眼蜂不同地理种群之间的遗传距离在0.002~0.020之间.种群系统聚类树分支结构和Mantel相关性分析结果表明,玉米螟赤眼蜂各地理种群的遗传距离与地理距离间不具有显著的相关性. 相似文献
135.
Identifying earthworms through DNA barcodes 总被引:1,自引:0,他引:1
With almost 3000 species, earthworms provide important model systems for studying soil fauna. However, species identification of earthworms is difficult and therefore limiting. The use of DNA barcodes, which are short sequences from standardized regions of the genome, has been regarded as a promising approach to resolve this taxonomic dilemma. We evaluated sequence diversity in the mitochondrial cytochrome-c oxidase I (COI) gene as a tool for resolving differences among species of Chinese earthworms. Members of six genera and 28 species were examined, and species were successfully discriminated in all cases. Sequence divergence within species was generally less than 1%, whereas divergence between species was greater than 15% in all cases. Divergence among individuals of Eisenia fetida were much higher (up to 7.8%); however, this may represent the presence of unrecognized sibling species or subspecies. We conclude that although it cannot completely replace taxonomy, the DNA barcode is a powerful tool for identifying species of earthworms and provides a useful complement to traditional morphological taxonomy. 相似文献
136.
天蚕、柞蚕线粒体DNA(mtDNA)的限制性酶切电泳图谱 总被引:2,自引:0,他引:2
采用差速离心和碱变性法,以9种限制性内切核酸酶对天蚕和柞蚕mtDNA进行了单酶切分析,发现这两种蚕的mtDNA在分子长度和酶切类型上存在明显差异。还对天蚕、柞蚕、蓖麻蚕和家蚕的mtD-NA限制性酶切电泳图谱进行了比较研究。 相似文献
137.
Allele‐specific polymerase chain reaction typing and sequencing of mitochondrial D‐loop region in broiler chickens in Japan
下载免费PDF全文
![点击此处可从《Animal Science Journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This study aimed to comprehend a feature of single nucleotide polymorphism (SNP) in mitochondrial DNA (mtDNA) mainly of general broiler chickens in Japan. We typed two SNP sites (199C/T and 792A/G) of the D‐loop region in mtDNA by allele‐specific PCR (AS‐PCR) in 359 broiler (182 chunky and 177 cobb) and 506 layer (233 White Leghorn, 140 Barred Plymouth Rock and 133 Rhode Island Red) chickens. The SNP of 199C or 792A by AS‐PCR was observed in the chunky and cobb chickens, and not in the layers. The haplotype 199T/792G was observed in a part of cobb and all layers. By the result of AS‐PCR haplotyping and the broiler brands, the D‐loop region was sequenced in 44 broiler chickens (20 chunky and 24 cobb) and compared with the layers’ sequence data. Among the broiler and layer chickens, 21 SNP sites (including one insertion) and 11 sequence haplotypes were observed. Haplotype variation or correspondence was observed in and between the broiler brands. This study provides important information to establish a chicken meat traceability system by SNP haplotyping of mtDNA in Japan. 相似文献
138.
In order to compare the genetic diversity and phylogenetic relationships between Guangxi pig breeds and three exotic pig breeds,one pair of primers was used to amplify 85 mtDNA D-loop sequences of five Guangxi pig breeds (Bama Xiang pig,Dongshan pig,Guizhong spotted pig,Luchuan pig,Huanjiang Xiang pig),and we downloaded 45 mtDNA D-loop sequences of three exotic pig breeds (Duroc,Yorkshire,Landrace) from GenBank.Then the haplotype,genetic diversity and phylogenetics analysis were carried out.The results showed that 38 haplotypes were identified in 130 sequences,and the mean distances among Guangxi pig breeds were smaller than that among Duroc,Landrace and Guangxi pig breeds.The NJ phylogenetic tree classified all samples into two clusters.One contained all of Guangxi pig breeds and partial Yorkshire,the other was composed wholly of exotic pig breeds,which mean there were two distinct maternal origins.In the cluster of Guangxi pig breeds,Luchuan pig were clustered,and the others were rather dispersive.It indicated that Luchuan pig had simple maternal bloods,and the other breeds had complex maternal bloods,and they had gene flow with each other.The maternal pig resources in Guangxi were not affected by the introduction of exotic pig breeds,and they were still suitable for use as a female parent in their development and utilization. 相似文献
139.
Xianglong Li Zengli Zhang Yuanfang Gong Zhengzhu Liu Qing Jia Lize Wang 《Frontiers of Agriculture in China》2007,1(3):352-356
The polymorphism of mitochondrial DNA (mtD-NA) D-loop of 83 individuals from nine Chinese indigenous sheep breeds and two
imported sheep breeds was studied with five endonucleases, Hinf I, Msp I, Sau3 A I, Xsp I and Taq I, using PCR-RFLP. The results indicated that there existed two basic haplotypes in the region of mtDNA D-loop. It could
be inferred that Chinese indigenous sheep breeds originated from two maternal ancestors. The average polymorphic degree (π value = 0.0421%) of mtDNA D-loop showed that the genetic diversity of mtDNA of Chinese indigenous sheep breeds was very low.
Translated from Hereditas, 2006, 28(2): 165–170 [译自: 遗传] 相似文献
140.