首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   859篇
  免费   81篇
  国内免费   91篇
林业   19篇
农学   111篇
基础科学   6篇
  53篇
综合类   311篇
农作物   78篇
水产渔业   98篇
畜牧兽医   259篇
园艺   40篇
植物保护   56篇
  2024年   1篇
  2023年   14篇
  2022年   36篇
  2021年   35篇
  2020年   50篇
  2019年   47篇
  2018年   41篇
  2017年   45篇
  2016年   49篇
  2015年   39篇
  2014年   49篇
  2013年   63篇
  2012年   55篇
  2011年   63篇
  2010年   67篇
  2009年   50篇
  2008年   46篇
  2007年   49篇
  2006年   32篇
  2005年   32篇
  2004年   35篇
  2003年   28篇
  2002年   23篇
  2001年   20篇
  2000年   17篇
  1999年   10篇
  1998年   3篇
  1997年   7篇
  1996年   7篇
  1995年   6篇
  1994年   6篇
  1993年   2篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1955年   1篇
排序方式: 共有1031条查询结果,搜索用时 19 毫秒
51.
52.
To assess the role of muscle fiber type in beef taste‐traits, we analyzed cooked meats from bovine masseter, diaphragm, psoas major, longissimus thoracis, and semitendinosus muscles with an electric taste sensing system (INSENT SA402B). The system is composed of five taste sensors of polymer membranes fixing different lipids. The sensors, CT0, CA0, AAE, C00 and AE1 are designed to respond to the individual tastes of salty, sour, umami, bitter and astringent, respectively. The system found significant differences in the converted outputs of CA0 (cvCA0), C00 (cvC00) and AE1 (cvAE1) among the bovine muscles. The slow‐type muscles (masseter and diaphragm) showed lower cvCA0, higher cvC00, and higher cvAE1 than did the fast‐type muscles (psoas major, longissimus thoracis, and semitendinosus). Lactic acid content was different among muscle types and was highly related to the cvCA0 output and pH. carbonyl compounds and free fatty acids were higher in the slow‐type muscles. Free fatty acids were major components causing the difference in the C00 output among the muscle types. Iron content was also different among the muscle types and related to the cvC00 and cvAE1 outputs. These results suggested that the muscle fiber type affects the beef taste characteristics.  相似文献   
53.
This study describes the development of efficient single nucleotide polymorphism (SNP) markers for individual identification and parentage tests in a Japanese Black cattle population. An amplified fragment length polymorphism method was employed to detect informative candidate markers, and yielded 44 SNP markers from 220 primer combinations. 29 unlinked SNPs were finally selected as diagnostic markers. The allelic frequencies for each marker were estimated by using PCR‐RFLP in the Japanese Black population. Based on the frequency data, the estimated identity power of these markers was 2.73 × 10?12. Parentage exclusion probabilities, when both suspected parents' genotypes were known and when only one suspected parent was genotyped, were estimated as 0.96929 and 0.99693, respectively. This panel of SNP markers is theoretically sufficient for individual identification, and would also be a powerful tool for a parentage test in Japanese Black cattle. The markers could contribute to the management of the beef industry in Japan.  相似文献   
54.
单核苷酸多态性(sNP),被称为第三代遗传标记,广泛存在于植物基因组中,其位点丰富,遗传稳定性高,在遗传图谱构建、生物多样性研究、基因定位、关联分析等方面都具有重要的作用,目前已经成为医学研究的重要工具,而在木育种研究中的使用尚处于起步阶段.综述了用于植物SNP研究的主要方法和当前SNP分子标记技术在林木育种中应用的研究进展.并展望了其在林木育种中的应用前景.  相似文献   
55.
利用PCR-SSCP与测序相结合,分析海南黑山羊GH基因第2外显子exon2的多态性,SSCP结果出现3种基因型,分别定义为AA、AB、BB;3种基因型频率分别为28.3%、63.0%、8.7%,A、B等位基因频率分别为59.8%和40.2%,以A等位基因为优势基因,经Hardy-Weinberg平衡卡方适合性检验结果表明,exon2在此群体中处于Hardy-Weinberg不平衡状态(X2=0.000,P〈0.01),该位点群体遗传结构及多态指标分析结果显示,该位点表现为中度多态。AA和BB基因型进行测序结果发现,exon2第11位点发生G→C突变,将核苷酸序列翻译成氨基酸序列进行同源性比较,结果exon2第11位G→C突变位点引起编码的氨基酸改变,所编码的氨基酸由原来的精氨酸变为脯氨酸。  相似文献   
56.
小米食味(适口性)评价方法研究   总被引:1,自引:0,他引:1  
常规化学分析测试方法和百分制感观评定方法是目前小米进行适口性评价的二种主要方法。笔者以小米的色泽、芳香、味道、粘性、回生以及综合评价等六项感观性状为评定指标,设3、2、1、0、-1、-2、-3共7个评判值,以统一对照(晋谷21号)为参照,对参评品种的评判平均数进行T测验统计评价分析。评价分析结果:长农35号食味值为1.389,长农39号食味值为1.000,两个品种品尝食味值高,与晋谷21号达到95%水平上的显著差异,是适口性好的优质小米品种。该分析结果与前二种方法基本一致,分析方法方便科学,可以作为一种新的小米适口性评价方法。  相似文献   
57.
文昌鸡促卵泡素受体基因外显子区域SNPs分析   总被引:1,自引:1,他引:0  
寻找与鸡繁殖性能相关的遗传标记,为高繁殖力的标记辅助选择提供科学依据。本研究以促卵泡素受体(FSHR)基因作为影响鸡繁殖性状的候选基因,采用PCR-SSCP技术结合测序对FSHR基因部分包括所有外显子区域进行单核苷酸多态性检测和分析。结果发现,在区域2、区域4、区域6、区域9共4个区域存在SNPs位点。exon4编码区43 bp处T→C突变,但没有导致翻译后氨基酸序列的改变,在exon2中编码区5′端—49 bp处的C→T突变;exon6 编码区3′端+12 bp处的A→G突变;exon8编码区3′端+38 bp处的 G→T突变。促卵泡素受体(FSHR)是促卵泡素(FSH)的特异性受体,这些位点的单核苷酸多态性为下一步研究探讨FSHR基因对文昌鸡繁殖性能的遗传效应奠定了基础。  相似文献   
58.
59.
《农业科学学报》2019,18(10):2351-2360
As a member of the Frizzled family, Frizzled3(FZD3) is a receptor of the canonical Wnt signaling pathway and plays a vital role in mammalian hair follicle developmental processes. However, its effects on wool traits are not clear. The objectives of this study were to identify the single nucleotide polymorphisms(SNPs) and the expression patterns of FZD3 gene, and then to determine whether it affected wool traits of Chinese Merino sheep(Xinjiang Type) or not. PCR-single stranded conformational polymorphism(PCR-SSCP) and sequencing were used to identify mutation loci, and general linear model(GLM) with SAS 9.1 was used for the association analysis between wool traits and SNPs. Quantitative real-time PCR(q RTPCR) was used to investigate FZD3 gene expression levels. The results showed that six exons of FZD3 gene were amplified and two mutation loci were identified in exon 1(NC_019459.2: g.101771685 TC(SNP1)) and exon 3(NC_019459.2: g.101810848, AC(SNP2)), respectively. Association analysis showed that SNP1 was significantly associated with mean fiber diameter(MFD)(P=0.04) and live weight(LW)(P=0.0004), SNP2 was significantly associated with greasy fleece weight(GFW)(P=0.04). The expression level of FZD3 gene in skin tissues of the superfine wool(SF) group was significantly lower(P0.05) than that of the fine wool(F) group. Moreover, it had a higher expression level(P0.01) in skin tissues than in other tissues of Chinese Merino ewes. While, its expression level had a fluctuant expression in skin tissues at different developmental stages of embryos and born lambs, with the highest expression levels(P0.01) at the 65 th day of embryos. Our study revealed the genetic relationship between FZD3 variants and wool traits and two identified SNPs might serve as potential and valuable genetic markers for sheep breeding and lay a molecular genetic foundation for sheep markerassisted selection(MAS).  相似文献   
60.
Salinity is a common abiotic stress causing soybean [Glycine max (L.) Merr.] yield loss worldwide. The use of tolerant cultivars is an effective and economic approach to coping with this stress. Towards this, research is needed to identify salt‐tolerant germplasm and better understand the genetic and molecular basis of salt tolerance in soybean. The objectives of this study were to identify salt‐tolerant genotypes, to search for single‐nucleotide polymorphisms (SNPs) and QTLs associated with salt tolerance. A total of 192 diverse soybean lines and cultivars were screened for salt tolerance in the glasshouse based on visual leaf scorch scores after 15–18 days of 120 mM NaCl stress. These genotypes were further genotyped using the SoySNP50K iSelect BeadChip. Genomewide association mapping showed that 62 SNP markers representing six genomic regions on chromosomes (Chr.) 2, 3, 5, 6, 8 and 18, respectively, were significantly associated with salt tolerance (p < 0.001). A total of 52 SNP markers on Chr. 3 are mapped at or near the major salt tolerance QTL previously identified in S‐100 (Lee et al., 2014). Three SNPs on Chr. 18 map near the salt tolerance QTL previously identified in Nannong1138‐2 (Chen, Cui, Fu, Gai, & Yu, 2008). The other significant SNPs represent four putative minor QTLs for salt tolerance, newly identified in this study. The results above lay the foundation for fine mapping, cloning and molecular breeding for soybean salt tolerance.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号