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   559篇
  免费   36篇
  国内免费   1篇
林业   40篇
农学   26篇
  75篇
综合类   13篇
农作物   16篇
水产渔业   60篇
畜牧兽医   333篇
园艺   9篇
植物保护   24篇
  2023年   3篇
  2022年   3篇
  2021年   23篇
  2020年   9篇
  2019年   18篇
  2018年   20篇
  2017年   16篇
  2016年   28篇
  2015年   13篇
  2014年   28篇
  2013年   40篇
  2012年   38篇
  2011年   41篇
  2010年   12篇
  2009年   26篇
  2008年   33篇
  2007年   36篇
  2006年   39篇
  2005年   24篇
  2004年   18篇
  2003年   22篇
  2002年   15篇
  2001年   12篇
  2000年   13篇
  1999年   9篇
  1998年   3篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1992年   4篇
  1991年   4篇
  1990年   2篇
  1989年   7篇
  1988年   3篇
  1987年   5篇
  1986年   1篇
  1985年   8篇
  1984年   3篇
  1983年   1篇
  1980年   2篇
  1979年   3篇
  1977年   1篇
  1975年   2篇
  1974年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1966年   1篇
排序方式: 共有596条查询结果,搜索用时 706 毫秒
1.
Paddy and Water Environment - This paper revealed the irrigation rate by groundwater, evapotranspiration (ET), total water balance and yield in the experimental rice and mung bean fields in a...  相似文献   
2.
3.
4.
5.
The rumen microbiota comprises a vast range of bacterial taxa, which may affect the production of high-quality meat in Japanese Black cattle. The aim of this study was to identify core rumen microbiota in rumen fluid samples collected from 74 Japanese Black cattle raised under different dietary conditions using 16S rRNA gene amplicon sequencing. In the rumen of fattening Japanese Black cattle, 10 bacterial taxa, showing >1% average relative abundance and >95% prevalence, irrespective of the dietary conditions and the fattening periods, were identified as the core rumen bacterial taxa, which accounted for approximately 80% of the rumen microbiota in Japanese Black cattle. Additionally, population dynamics of the core rumen bacterial taxa revealed two distinct patterns: Prevotella spp. and unclassified Bacteroidales decreased in the mid-fattening period, whereas unclassified Clostridiales, unclassified Ruminococcaceae, Ruminococcus spp., and unclassified Christensenellaceae increased during the same period. Therefore, the present study reports the wide distribution of the core rumen bacterial taxa in Japanese Black cattle, and the complementary nature of the population dynamics of these core taxa, which may ensure stable rumen fermentation during the fattening period.  相似文献   
6.
Insulin‐like growth factor‐1 (IGF‐1) is one of the important factors for growth, milk production and reproductive functions and mainly released from the liver in response to growth hormone (GH) via GH receptor (GHR) in cattle. Recently, some single nucleotide polymorphisms (SNPs) were identified in the bovine GHR gene. Some GHR‐SNPs were shown to be related to plasma IGF‐1 concentration in cattle. Hence, the capacity to IGF‐1 production in the liver might be affected by GHR‐SNP and associated with performance in the future. This study examined whether GHR‐SNP is associated with IGF‐1 production in the liver of pre‐pubertal heifers. In 71 Holstein calves, blood samples for genomic DNA extraction were obtained immediately after birth. To genotype the GHR‐SNPs in the promoter region, polymerase chain reaction (PCR) products were digested with restriction enzyme NsiI (cutting sites: AA, AG and GG). All heifers at 4 months of age were intramuscularly injected with 0.4 mg oestradiol benzoate. Blood samples were obtained from the jugular vein just before (0 h) and 24 h after injection. The number of AA, AG and GG at the NsiI site was 0, 17 and 54 respectively. In AG and GG, plasma GH concentrations were higher pre‐injection than 24 h post‐injection (p < 0.01). Moreover, plasma GH concentrations in AG post‐injection were higher than in GG (p < 0.05). In contrast, the GG genotype exhibited higher plasma IGF‐1 concentrations in pre‐injection than post‐injection (p < 0.01), although oestradiol did not change IGF‐1 concentration in the AG genotype. We conclude that the GG polymorphism in the promoter region of GHR is associated with a higher potential capacity of IGF‐1 production in the liver of cattle.  相似文献   
7.
To clarify the contribution of autologous transplantation of mesenchymal stromal cells (MSCs), an atelocollagen gel containing or not containing fluorescently-labeled canine MSCs was transplanted into an osteochondral defect which did not repair spontaneously and the histological repair of the defect was compared. Although an early repair of the cartilage was not observed in either defect, the reproduction of subchondral bone was remarkable in the MSCs-implanted defect. Moreover, in 2 weeks after operation, the implanted MSCs were located in the deeper regions of the defect, suggesting the differentiation of osteoblasts. There was a possibility that the movement of the implanted MSCs was due to an increase in intra-articular pressure from postoperative inflammation.  相似文献   
8.
9.
10.
Four Holstein cows were used to determine the effect of timing of the feeding of a corn silage (CS)‐based supplement on the feed intake, milk production and nitrogen utilization of grazing dairy cows. The cows were fed the supplement 2 h before grazing (pre‐grazing) or immediately after grazing (post‐grazing). Cows were grazed for 5 h per day under a rotational grazing system. There was no difference in the herbage and total feed intake between treatments. The milk protein yield for pre‐grazing tended to be higher than that for post‐grazing, whereas the milk yield did not differ between treatments. The total nitrogen intake for pre‐grazing tended to be higher than that for post‐grazing (P = 0.06). There was no difference in the urinary nitrogen output between treatments, whereas the proportion of urinary nitrogen output : total nitrogen intake for pre‐grazing tended to be lower than that for post‐grazing (P = 0.06). The milk nitrogen output and nitrogen retention for pre‐grazing tended to be higher than that for post‐grazing (milk nitrogen, P = 0.06; nitrogen retention, P = 0.05). Nitrogen utilization of grazing dairy cows was improved by feeding a CS‐based supplement before grazing.  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