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   220篇
  免费   7篇
  国内免费   1篇
林业   14篇
农学   14篇
基础科学   1篇
  35篇
综合类   10篇
农作物   12篇
水产渔业   13篇
畜牧兽医   110篇
园艺   4篇
植物保护   15篇
  2023年   2篇
  2022年   14篇
  2021年   16篇
  2020年   7篇
  2019年   3篇
  2018年   4篇
  2017年   6篇
  2016年   7篇
  2015年   10篇
  2014年   19篇
  2013年   20篇
  2012年   15篇
  2011年   24篇
  2010年   10篇
  2009年   12篇
  2008年   20篇
  2007年   13篇
  2006年   12篇
  2005年   4篇
  2004年   3篇
  2003年   4篇
  2002年   1篇
  2000年   1篇
  1998年   1篇
排序方式: 共有228条查询结果,搜索用时 15 毫秒
51.
A male Holstein-Friesian calf was born with multiple, cauliflower-like, pale pink cutaneous masses on the head and limbs. On histopathological examination, the cutaneous masses were diagnosed as congenital cutaneous fibropapillomatosis. Those lesions involved focal proliferation of sebaceous gland in the dermis. There were no histological findings to suggest bovine papillomavirus infection, such as the presence of intranuclear inclusion bodies, large keratohyalin granules, and koilocytosis. Furthermore, papillomaviral antigens and DNA were not detected by immunohistochemistry and polymerase chain reaction, respectively. These results suggested that there was no association between these cutaneous lesions and bovine papillomavirus infection, and the lesions were considered as harmartomatous changes.  相似文献   
52.
To provide useful information on how to moderate post‐handling stress, Angus heifers (n = 157) were individually allowed to enter a choice area after 2 min of restraint in a crush and to choose between two pens. After the animal had chosen a pen, free access was given to both test pens and the choice area for a further 5 min. The behaviors during choice and after the first choosing were observed. In experiment 1, each heifer was given one of the following choices: pen with three familiar heifers (peers) versus pen with six sheep (sheep; n = 30); peers versus the bare pen (bare; n = 30); sheep versus bare (n = 30). When the choice combination was peers versus bare, more heifers than expected by chance chose the peers pen (χ2 = 4.80; P < 0.05). However, when one of the other choice combinations was given, there was no significant difference between the number choosing a pen and the expected value. After the first choice, more heifers entered the peers pen than the bare pen (P < 0.05) or the sheep pen (P < 0.10). In experiment 2, another 67 heifers were given one of the following choices: peers versus pen with a novel object (NO; n = 19); sheep versus NO (n = 22); bare versus NO (n = 26). There was no significant difference between the number of heifers choosing a pen and the expected value in any choice combination. However, more heifers entered the peers pen than the NO pen (P < 0.01). It is concluded that sheep were not as attractive as peers, but sheep were not fearful animals for cattle.  相似文献   
53.
Adzuki bean is an important legume crop originating in temperate regions, with photoperiod in sensitivity being a key factor in its latitudinal adaptation. The Flowering Date1 (FD1) gene has a large effect on the photoperiodic response of flowering time, but the molecular basis for the effect of this locus is undetermined. The present study delimited the FD1 locus to a 17.1 kb sequence, containing a single gene, an E1 ortholog (VaE1). A comparison between Vigna angularis ‘Shumari’ (photoperiod insensitive) and ‘Acc2265’ (photoperiod sensitive) identified 29 insertions/deletions and 178 SNPs upstream of VaE1 in the FD1 locus. VaE1 expression in ‘Acc2265’ was greater under long-day than short-day conditions, whereas VaE1 expression in ‘Shumari’ was lower regardless of day length. These findings suggested that responsible gene of FD1 is a VaE1, which acts as a floral repressor by being upregulated in response to long-day conditions. The inability to upregulate VaE1 under long-day conditions was linked to its ability to flower under these conditions. These results provide greater understanding of the molecular control of a flowering date and clues enabling the breeding of adzuki bean at higher latitudes.  相似文献   
54.
基于PCA和聚类分析的茶树F1代茶多酚遗传分析   总被引:1,自引:0,他引:1  
高效液相色谱检测茶树(Camellia sinensis (L.) O.Kuntze) 14个红富贵×红交27的F1代单株、7个红交27×F95181 F1代单株及其亲本中各儿茶素组分含量,利用主成分分析和聚类分析研究了茶多酚在品种间杂交F1代的遗传规律.结果显示,红富贵×红交27 F1代14个单株茶多酚的表型以3:1...  相似文献   
55.
Deepwater rice possesses internode elongation ability to avoid drowning under deepwater conditions. Previous studies identified three QTLs regulating internode elongation ability on chromosomes 1, 3 and 12 using different populations. However, these QTLs only induce internode elongation in response to deepwater conditions from the 7-leaf stage and not during the early leaf stage. In this study, we detected two novel QTLs, qTIL2 and qTIL4 regulating deepwater response at the early leaf stage using an F2 population derived from the cross between NIL1-3-12 carrying the three QTLs regulating deepwater response in T65 (O. sativa ssp. japonica) genetic background and C9285 (O. sativa ssp. indica, deepwater rice). Plants of the BC2F2 population derived from NIL1-3-12/C9285 and the RILs of T65/Bhadua (O. sativa ssp. indica, deepwater rice) possessing these QTLs as well as the three QTLs previously identified also showed internode elongation during the early leaf stage. These results indicate that qTIL2 and qTIL4 regulate early internode elongation and function in coordination with the three major QTLs under deepwater conditions. The results presented here would not only help define the mechanism of deepwater response in rice but also contribute in the breeding of deepwater tolerant rice that is adapted to various water depths.  相似文献   
56.
干旱区制种玉米农田蒸散研究   总被引:1,自引:1,他引:1  
在黑河流域中游的张掖绿洲区建立了大田环境下的制种玉米农田蒸散研究观测点,以气象观测资料为基础,采用波文比能量平衡法(BREB)和参考作物蒸散量作物系数法(ET0Kc)对制种玉米的蒸散进行了计算。结果表明,在一个完整的生长期内,利用波文比能量平衡法得到的蒸散量为513.2 mm,日均3.2 mm/d,用参考作物蒸散量作物系数法得到的作物蒸散量为486.2 mm,日均3.1 mm/d,2种计算方法得到的蒸散量总值差别小。利用波文比能量平衡法所得结果的分析表明,试验地在不同生长阶段,ET变化剧烈,生长初期、发育期、中期、末期分别为2.3、2.9、4.1和3.0 mm/d,其蒸散量分别约占全年蒸散总量的13%、22%、50%和16%。ET月变化显示,4月和5月维持在一个较低水平,平均为2.1-2.3 mm/d;6月剧烈增加到3.6 mm/d;7月达到最大,平均为4.6mm/d;8月蒸散有所降低,为3.3 mm/d;9月,随着作物进入生长末期,蒸散急剧减小到2.8 mm/d。  相似文献   
57.
Journal of Soils and Sediments - In modern times, farmlands in Japan have been reconstructed at a large-scale through the cutting and filling of soils. In principle, such reconstruction should be...  相似文献   
58.
Optimization of the solid-phase extraction cleanup procedure enabled the GC-MS analysis of acrylamide in tea samples without the interference of bromination by tea catechins. Although polyvinylpolypyrrolidone (PVPP) is available for removing tea catechins from tea extract, the peaks derived from PVPP had the same retention time as brominated acrylamide in mass chromatograms obtained by GC-MS. A considerable amount of acrylamide was formed at roasting temperatures of > or =120 degrees C; the highest acrylamide level was observed when tea samples were roasted at 180 degrees C for 10 min. Higher temperatures and longer processing times caused a decrease in the acrylamide content. Furthermore, an analysis of 82 tea samples showed that rather than the reducing sugar content, the asparagine content in tea leaves was a significant factor related to acrylamide formation in roasted products. The acrylamide level in roasted tea products was controlled by asparagine in the presence of reducing sugars.  相似文献   
59.
Abstract

The synthetic activity of protein and changes in the activity profiles of enzymes during cold acclimation were studied in leaves, stems, and crowns of a hardy winter wheat cultivar ( Triticum aestivum L. cv. Horoshirikomugi) and a less hardy winter wheat cultivar (Triticum aestivum L. cv. Norin 61). The results showed that one of the genetic differences between the two cuitivars is found in the activities of protein synthesis under low temperatures. The profiles of the changes in enzymatic activities showed that the adjustment of enzymatic activities was a tissue-specific event to accommodate environmental changes. The synthesis of the enzymes involved in a peroxide scavenging system such as hexokinase, glucose-6-phosphate dehydrogenase, dehydroascorbate reductase, ascorbate peroxidase, and so on started at the acclimation stage, while the phosphoglucose isomerase, which appears to be a maintenance-type enzyme in the wintering wheat, showed a small increase in the activity at later stages of acclimation period in their stems of both cuitivars. When the field was covered with snow, the catalase activity in the leaves started to decrease abruptly, while catalase activities in the stems and crowns did not exhibit appreciable changes during the life under snow. The life-cycle dependent changes in enzymatic activities appear to occur in late March or early April under snow.  相似文献   
60.
The soil temperature regime map provides for utilitarian classification that can be superimposed on soil classification to permit more precise interpretations and assessments of land use. The objects of this study are (1) to clarify the relationship between soil temperature and meteo-geographical factors, and then (2) to delineate detailed soil temperature regime map (1?km grid) as Japanese land resources inventory. There was a parallel relationship between mean annual soil temperature (MAST) and mean annual air temperature (MAAT), but this relationship was affected to some extent by the mean annual wind speed and mean annual global irradiation in this study. Furthermore, the difference between MAST and MAAT [Diff(MAST–MAAT)] showed the highest correlation with elevation. The map of RK_Diff(MAST–MAAT) was computed using this meteo-geographical relationship with the regression-kriging approach, and then the map of MAST and the soil temperature regime map were delineated using the map of MAAT and the RK_Diff(MAST–MAAT). The root mean square error of this delineation procedure was 0.47°C. It was clear that the majority of the Japanese soils had “mesic” soil temperature regime, and Japanese agricultural land was mainly distributed at “mesic” area and followed by “thermic”, “frigid”, and “hyperthermic” area. For promoting this land resource inventory, the soil temperature regime map will be uploaded on “Soil Information Web Viewer (http://agrimesh.dc.affrc.go.jp/soil_db/)”, which is provided by the National Institute for Agro-Environmental Sciences.  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