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   101篇
  免费   15篇
  国内免费   3篇
林业   3篇
  3篇
综合类   33篇
水产渔业   1篇
畜牧兽医   69篇
植物保护   10篇
  2023年   2篇
  2021年   1篇
  2020年   5篇
  2019年   2篇
  2018年   3篇
  2017年   7篇
  2016年   2篇
  2015年   5篇
  2014年   8篇
  2013年   12篇
  2012年   2篇
  2011年   2篇
  2010年   2篇
  2009年   7篇
  2008年   1篇
  2007年   3篇
  2005年   4篇
  2004年   1篇
  2003年   3篇
  2002年   1篇
  2001年   2篇
  2000年   2篇
  1999年   4篇
  1998年   6篇
  1997年   3篇
  1996年   2篇
  1995年   2篇
  1994年   1篇
  1993年   4篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1986年   1篇
  1982年   2篇
  1979年   1篇
  1978年   1篇
  1974年   2篇
  1970年   2篇
  1969年   1篇
  1966年   1篇
  1941年   1篇
  1933年   1篇
  1932年   1篇
  1930年   1篇
  1920年   1篇
排序方式: 共有119条查询结果,搜索用时 31 毫秒
1.
2.
3.
Effects of adding different concentrations of melatonin (10?7, 10?9 and 10?11 M) to maturation (Experiment 1; Control, IVM  + 10?7, IVM  + 10?9, IVM  + 10?11) and culture media (Experiment 2; Control, IVC  + 10?7, IVC  + 10?9, IVC  + 10?11) were evaluated on in vitro bovine embryonic development. The optimal concentration of melatonin (10?9 M) from Experiments 1–2 was tested in both maturation and/or culture media of Experiment 3 (Control, IVM  + 10?9, IVC  + 10?9, IVM /IVC  + 10?9). In Experiment 1, maturated oocytes from Control and IVM  + 10?9 treatments showed increased glutathione content, mitochondrial membrane potential and percentage of Grade I blastocysts (40.6% and 43%, respectively). In Experiment 2, an increase in the percentage of Grade I blastocysts was detected in IVC  + 10?7 (43.5%; 56.7%) and IVC  + 10?9 (47.4%; 57.4%). Moreover, a lower number and percentage of apoptotic cells in blastocysts were observed in the IVC  + 10?9 group compared to Control (3.8 ± 0.6; 3.6% versus 6.1 ± 0.6; 5.3%). In Experiment 3, the IVC  + 10?9 treatment increased percentage of Grade I blastocysts with a lower number of apoptotic cells compared to IVM /IVC  + 10?9 group (52.6%; 3.0 ± 0.5 versus 46.0%; 5.4 ± 1.0). The IVC  + 10?9 treatment also had a higher mRNA expression of antioxidant gene (SOD 2) compared to the Control, as well as the heat shock protein (HSPB 1) compared to the IVM  + 10?9. Reactive oxygen species production was greater in the IVM /IVC  + 10?9 treatment group. In conclusion, the 10?9 M concentration of melatonin and the in vitro production phase in which it is used directly affected embryonic development and quality.  相似文献   
4.
This study evaluated the reproductive performance of gilts inseminated at three intervals before ovulation (0-12, 13-23, 24-30 h) with sperm doses (SD) stored for 0-48 and 96-120 h. A total of 218 PIC Camborough 22 gilts were inseminated once with SD of 1.5 x 10(9) sperms. Pregnant gilts (n = 166) were slaughtered 30.8 +/- 3.7 days after artificial insemination. The number of corpora lutea (CL) and total embryos (TE) was counted. Pregnancy rates (PR) were analysed by chi-square test. TE and embryonic survival (ES), obtained as the ratio between viable embryos and CL, were analysed by GLM procedure (SAS) and mean values were compared by Tukey's test. Pregnancy rate was similar among artificial insemination-ovulation (AIOV) intervals when semen was stored for 0-48 h. However, the lowest PR was observed in the 24-30 h AIOV interval with storage time (ST) of 96-120 h (p < 0.05). There was a significant effect of the interaction between ST and AIOV (p < 0.05) on TE and ES variables. Total embryos and ES did not differ (p > 0.05) among AIOV intervals in ST of 0-48 h. However, gilts inseminated at 24-30 h AIOV interval with ST of 96-120 h showed a reduction of 6.7 embryos (p < 0.05) compared with gilts in the same interval inseminated with semen stored for 0-48 h. ES for the 24-30 h AIOV interval and ST of 96-120 h was lower than that observed in the other groups (p < 0.05).  相似文献   
5.
6.
复方泛菌克是(犬毒必治)一种新型高效复方抗菌、抗病毒药物,能迅速消除动物肠毒素和内毒素,增强胃肠吸收能力,提高机体免疫功能。试验用犬毒必治对30只患犬细小病毒的病犬进行治疗,治愈28只,死亡2只,治愈率为93.3%。  相似文献   
7.
ABSTRACT Hydathodes of tomato leaves served as extremely efficient infection courts for the bacterial canker pathogen, Clavibacter michiganensis subsp. michiganensis. Chlorotic lesions developed at the tips of leaflet lobes about 2 weeks after inoculation of guttation droplets. Lesions expanded along the leaflet margins and became necrotic. Movement of C. michiganensis subsp. michiganensis from the inoculated leaflet into the rachis was slow and erratic. Histological observations revealed that pathogen populations first developed within large intercellular spaces lying beneath the stomata, which serve as water pores in tomato hydathodes. Bacteria were first observed within vessels of the large marginal fimbriate veins 7 days after inoculation. By 14 days after inoculation, large populations could be seen within the vessels; and by 21 days after inoculation, tissue collapse was widespread and masses of bacteria could be seen in the intercellular spaces and within necrotic cells.  相似文献   
8.
9.
10.
The study evaluated the reproductive performance of primiparous sows submitted to post‐cervical insemination (PCAI) compared with cervical artificial insemination (CAI). Difficulty with catheter introduction, the occurrence of bleeding or semen backflow during insemination, and volume and sperm cell backflow up to 60 min after insemination were also evaluated. Sows were homogenously distributed, according to body weight loss in lactation, lactation length, weaned piglets, weaning‐to‐oestrus interval and total born in previous farrowing, in two treatments: PCAI (n = 165) with 1.5 × 109 sperm cells in 45 ml (2.4 ± 0.04 doses per sow) and CAI (n = 165) with 3 × 109 sperm cells in 90 ml (2.5 ± 0.04 doses per sow). During PCAI, sows were inseminated in the absence of boars. Transabdominal real‐time ultrasonography was performed at oestrus onset, immediately before the first insemination and at 24 h after last insemination. There was no difference (P > 0.05) between treatments in farrowing rate (91.5% × 89.1%) and litter size (12.5 × 11.9 piglets born, respectively for PCAI and CAI sows). Successful passage of the intrauterine catheter in all the inseminations was possible in 86.8% (165/190) of sows initially allocated to PCAI treatment. Difficulty of introducing the catheter in at least one insemination did not affect the reproductive performance of PCAI sows (P > 0.05). Bleeding during insemination did not affect (P > 0.05) the farrowing rate in both treatments, but litter size was reduced in CAI and PCAI sows (P ≤ 0.06). Percentage of spermatozoa present in backflow within 1 h after insemination was greater in CAI than PCAI sows (P < 0.01). More than 85% of primiparous sows can be successfully post‐cervical inseminated with doses containing 1.5 × 109 sperm cells in the absence of the boar during insemination without impairing the reproductive performance.  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