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   104篇
  免费   10篇
  国内免费   1篇
林业   12篇
农学   6篇
  24篇
综合类   8篇
农作物   5篇
水产渔业   17篇
畜牧兽医   37篇
园艺   1篇
植物保护   5篇
  2021年   6篇
  2018年   3篇
  2017年   5篇
  2016年   11篇
  2015年   4篇
  2014年   1篇
  2013年   11篇
  2012年   6篇
  2011年   6篇
  2010年   1篇
  2009年   3篇
  2008年   9篇
  2007年   8篇
  2006年   6篇
  2005年   8篇
  2004年   5篇
  2003年   9篇
  2002年   1篇
  2001年   3篇
  2000年   5篇
  1999年   2篇
  1998年   1篇
  1993年   1篇
排序方式: 共有115条查询结果,搜索用时 15 毫秒
111.
In the present study, we examined the effect of high water temperature on brain-pituitary-gonad (B-P-G) axis of a perciform fish red seabream, Pagrus (Chrysophrys) major during its spawning season (April-May). High water temperature negatively affected all levels in B-P-G axis and turned out to be the termination factor of the spawning season of this species.  相似文献   
112.
It has been reported that mature adipocyte-derived dedifferentiated fat (DFAT) cells show multilineage differentiation potential similar to that observed in mesenchymal stem cells. Since DFAT cells can be prepared from a small quantity of adipose tissue, they could facilitate cell-based therapies in small companion animals such as cats. The present study examined whether multipotent DFAT cells can be generated from feline adipose tissue, and the properties of DFAT cells were compared with those of adipose-derived stem cells (ASCs). DFAT cells and ASCs were prepared from the floating mature adipocyte fraction and the stromal vascular fraction, respectively, of collagenase-digested feline omental adipose tissue. Both cell types were evaluated for growth kinetics, colony-forming unit fibroblast (CFU-F) frequency, immunophenotypic properties, and multilineage differentiation potential.DFAT cells and ASCs could be generated from approximately 1 g of adipose tissue and were grown and subcultured on laminin-coated dishes. The frequency of CFU-Fs in DFAT cells (35.8%) was significantly higher than that in ASCs (20.8%) at passage 1 (P1). DFAT cells and ASCs displayed similar immunophenotypes (CD44+, CD90+, CD105+, CD14?, CD34? and CD45?). Alpha-smooth muscle actin-positive cells were readily detected in ASCs (15.2 ± 7.2%) but were rare in DFAT cells (2.2 ± 3.2%) at P1. Both cell types exhibited adipogenic, osteogenic, chondrogenic, and smooth muscle cell differentiation potential in vitro. In conclusion, feline DFAT cells exhibited similar properties to ASCs but displayed higher CFU-F frequency and greater homogeneity. DFAT cells, like ASCs, may be an attractive source for cell-based therapies in cats.  相似文献   
113.
The aim of the present study was to describe the temperature of the different portions of the female genital tract and their relation to rectal temperature and to investigate the effect of steroid hormones profiles on these variables over the estrous cycle in cattle. Four nonpregnant Japanese Black cows were investigated daily over two successive estrous cycles using a digital thermometer with a long probe and rounded-end sensor to record the temperature of the rectum (RT), vagina (VT), cervix (CT), uterine body (UBT) and uterine horns (UHT). Blood samples were collected immediately before temperature recording to assay peripheral levels of progesterone (P4) and estradiol-17β (E2). Moreover, transrectal ultrasonography was carried out after temperature recording to monitor the ovulatory follicle and track ovulation. During the experiment, the ambient temperature and relative humidity were recorded for further calculation of the temperature humidity index (THI). The temperature within the genital tracts in these cows progressively increased towards the uterine horns from the vagina. The VT, CT, UBT and UHTs were significantly higher in association with peripheral P4 concentrations greater than 4 ng/ml (mid-luteal phase) when compared with lower peripheral P4 concentrations. The VT was more significantly (P<0.01) correlated to the CT, UBT and UHTs than RT. In conclusion, a temperature gradient was present among the vagina, cervix and uterus over the estrous cycle, and changes in peripheral P4 concentrations were associated with the thermal variations within these portions. The VT could be more beneficial than RT in monitoring temperature of deeper portions of the female genital tract in bovine.  相似文献   
114.
Compositions of the xylem fluid of arsenic (As)-stressed hydroponic barley (Hordeum vulgare L. cv. Minorimugi) were investigated. The seedlings were treated with 0, 6.7, 33.5, and 67???M As in the form of arsenite. The xylem fluids were collected from the cut surface of plants 14?days after treatments and analyzed. Arsenic toxicity reduced the flow rate of xylem fluid. Mineral concentrations of the xylem fluid were measured with particle-induced X-ray emission system, but organic solutes were measured with high-performance liquid chromatography. Arsenic did not influence the concentrations of phosphorus (P), potassium (K), magnesium (Mg), and iron (Fe) very much. However, the concentrations of manganese (Mn), zinc (Zn), and copper (Cu) increased resulting in fairly stable translocation of the elements. The concentration and translocation of Ca decreased in the xylem fluid with increasing As concentrations in the medium. Arsenic concentration increased with increasing As in the nutrient solution, but its translocation decreased. Arsenic treatments did not affect phytosiderophore concentration very much, but their translocation decreased. The concentration of citrate increased but that of malate and succinate decreased in 33.5???M As-treated plants.  相似文献   
115.
比较了NaOH和Na2CO3对水冬瓜油(酸值22 mg/g)的碱炼效果,并应用正交和单因子试验,分析了Na2CO3溶液浓度、反应温度、反应搅拌强度和水洗温度4种因子对水冬瓜油碱炼降酸效果的影响,确定了碱炼降酸的最佳Na2CO3用量和Na2CO3碱炼水冬瓜油的最优工艺条件。结果表明,Na2CO3碱炼效果优于NaOH;以碱炼油的得率和酸值为指标,Na2CO3碱炼水冬瓜油的最佳反应条件为:Na2CO3水溶液浓度为170 g/L,反应温度为75℃,搅拌速度为100 r/min,水洗温度为80℃,固体Na2CO3用量为105 g/kg;在此条件下,水冬瓜毛油的酸值可降至1mg/g以下,可作为碱催化酯交换法制备生物柴油的原料。  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