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   208篇
  免费   4篇
林业   16篇
农学   7篇
  26篇
综合类   5篇
农作物   4篇
水产渔业   13篇
畜牧兽医   102篇
园艺   1篇
植物保护   38篇
  2022年   4篇
  2021年   19篇
  2020年   4篇
  2018年   1篇
  2017年   2篇
  2016年   9篇
  2015年   12篇
  2014年   10篇
  2013年   15篇
  2012年   8篇
  2011年   8篇
  2010年   6篇
  2009年   6篇
  2008年   10篇
  2007年   17篇
  2006年   15篇
  2005年   9篇
  2004年   13篇
  2003年   13篇
  2002年   16篇
  2001年   7篇
  2000年   4篇
  1993年   1篇
  1992年   3篇
排序方式: 共有212条查询结果,搜索用时 15 毫秒
81.
82.
A 31-month-old Japanese Black cow (Bos taurus) aborted at 5 months of gestation with no clinical symptoms. Histopathological examination of the placenta and fetus revealed severe necrotic placentitis associated with numerous irregular degenerative fungi and inflammatory cells. Regular filamentous fungi were also detected, without inflammatory response in the fetal digestive and respiratory organs. Both fungi had aleurioconidia and septa in the placenta and fetal organs and immunohistochemically stained with antibodies against Aspergillus spp. Aspergillus terreus was isolated from the fetal lung and abomasal contents as confirmed using mycological and molecular methods. This is the first immunohistochemical, morphological, and molecular identification of A. terreus in bovine placenta and aborted fetuses.  相似文献   
83.
This study aimed to apply radar technology to a large quadruped animal. We first developed a non-contact respiration measurement system using millimeter-wave array radar for a horse in standing position. Specifically, we measured the respiration of a stationary domestic horse in stables. Simultaneously, we measured the respiration rate using infrared thermography and developed a method for analyzing the radar information while verifying the rate of agreement. Our results suggested that the radar technology detected breathing and accurately measured the respiration of a horse, despite variation in the breathing frequency. To the best of our knowledge, this is the first study to apply a non-contact respiration measurement system using millimeter-wave array radar has been applied to large animals in an upright position, thereby demonstrating its potential application in animal husbandry and welfare.  相似文献   
84.
The incidence of different types of luteal activity postpartum and their effect on reproductive performance were studied in 21 postpartum dairy cows. Progesterone concentrations in defatted milk collected 3 times a week were determined by EIA. Reproductive tract examination was undertaken every other week postpartum. Body weight and body condition score (BCS) were measured before and after calving and the average 100-day milk yield was calculated. Nine (42.9%) cows had normal ovarian activity (first luteal activity < or = 50 days postpartum followed by regular cycles), 5 (23.8%) had prolonged luteal phase (PLP; ovarian cycle with luteal activity > or = 20 days pre-service) and in 7 (33.3%) cows the first luteal activity was shown later than 50 days postpartum (DOV). When compared with normal cows, both PLP and DOV had longer interval to first insemination (63.1 +/- 22.0 days versus 77.6 +/- 21.6 and 93.0 +/- 22.3 days, P<0.05 and P<0.01, respectively), lower first insemination conception rate (88.9% versus 0.0% and 57.1%, P<0.01 and P<0.05, respectively) and greater BCS loss (0.81 +/- 0.2 versus 1.05 +/- 0.21 and 1.04 +/- 0.10, respectively, P<0.01). Cows with PLP showed longer interval to uterine involution than normal and DOV groups (54.0 +/- 8.3 days versus 42.4 +/- 5.5 and 43.3 +/- 8.3 days, respectively, P<0.01) and higher 100-day milk yield (38.8 +/- 2.7 kg versus 33.6 +/- 4.7 and 29.9 +/- 6.1 kg, respectively, P<0.01). In conclusion, more than half of the cows had abnormal luteal activity postpartum, which adversely affected reproductive performance.  相似文献   
85.
Degeneration of the optic pathway has been reported in various animal species including cattle. We experienced a case of bilateral optic tract degeneration characterized by severe gliosis in a Japanese black cattle without any obvious visual defects. To evaluate the significance, pathological nature and pathogenesis of the lesions, we examined the optic pathway in 60 cattle (41 Japanese black, 13 Holstein and 6 crossbreed) with or without ocular abnormalities. None of these animals had optic canal stenosis. Degenerative changes with severe gliosis in the optic pathway, which includes the optic nerve, optic chiasm and optic tract, were only observed in 8 Japanese black cattle with or without ocular abnormalities. Furthermore, strong immunoreactivity of glial fibrillary acidic protein was observed in the retinal stratum opticum and ganglion cell layer in all 5 cattle in which the optic pathway lesions could be examined. As etiological research, we also examined whether the concentrations of vitamin A and vitamin B12 or bovine viral diarrhea virus (BVDV) infection was associated with optic pathway degeneration. However, our results suggested that the observed optic pathway degeneration was probably not caused by these factors. These facts indicate the presence of optic pathway degeneration characterized by severe gliosis that has never been reported in cattle without bilateral compressive lesions in the optic pathway or bilateral severe retinal atrophy.  相似文献   
86.
Advanced reproductive technologies are being applied for the propagation of squirrel monkeys, to ensure their preservation as a genetic resource and the effective use of their gametes in the future. In the present study, oocytes and spermatozoa were collected from live squirrel monkeys, following which piezo intracytoplasmic sperm injection (ICSI) was performed using these gametes. Follicular development was induced by administering equine chorionic gonadotropin (eCG) containing inhibin antiserum to an immature squirrel monkey female. The unilateral ovary was excised after the administration of human chorionic gonadotropin (hCG), to induce ovulation, following which the larger developed follicular oocytes were collected. Follicular oocytes were prepared for ICSI using sperm from the epididymal tail of a unilateral testis extracted from a mature male. The embryos were continuously incubated in CMRL 1066 medium supplemented with 10% (v/v) fetal bovine serum. Embryo culture was performed with cumulus cells. Two experiments of ICSI carried out with three females resulted in 14 mature oocytes from the 49 cumulus-oocyte complexes collected and five embryos, three of which developed into blastocysts. These blastocysts were vitrified, thawed, and transferred to recipient monkeys, but no pregnancies resulted. In conclusion, the present study is the first to successfully produce ICSI-derived blastocysts from MII oocytes obtained by means of hormone administration (a combination of eCG+inhibin antiserum and hCG) and in vitro maturation in immature squirrel monkeys.  相似文献   
87.
建立了超高效液相色谱-质谱联用检测五氟磺草胺在水稻植株、稻田土壤、田水和糙米中残留的分析方法,结合田间试验研究了五氟磺草胺在稻田环境中的消解及残留特性,并对稻米中五氟磺草胺残留的膳食暴露进行了初步评估。结果表明:在0.005~0.5 mg/L范围内,五氟磺草胺的质量浓度与对应的峰面积间呈良好线性关系,检出限(LOD)为0.001~0.002 mg/kg,定量限(LOQ)为0.003~0.005 mg/kg。在0.005~0.5 mg/kg添加水平下,五氟磺草胺在水稻植株、稻田土壤、田水和糙米中的平均回收率在89%~106%之间,相对标准偏差在2.8%~8.5%之间。浙江、福建和黑龙江2年3地的田间试验表明:0.025%五氟磺草胺颗粒剂在水稻植株、稻田土壤和田水中的消解半衰期分别为1.5~3.3,3.0~4.7和1.6-3.0 d,说明该药剂在稻田环境中消解速率较快。以五氟磺草胺有效成分含量37.5和56.3 g/hm2分别施药1次,于水稻成熟期采样检测,发现其在糙米中的残留量低于0.005 mg/kg,表明其膳食摄入风险很低,该研究结果可为五氟磺草胺风险评估提供一定参考。  相似文献   
88.
ABSTRACT:   Ten newly hatched phyllosoma of Panulirus japonicus were cultured individually to monitor body length ( BL ) and intermolt period, and 2000 were cultured in groups to sample specimens for measurement of body weight. Phyllosoma were fed with Artemia and mussel gonad; the culture seawater temperature was 24–26°C. The individually cultured phyllosoma showed an increment in body length by the first molt of approximately 0.5 mm, and the molt increment increased to approximately 1 mm at 5 mm BL ; it was constant to 15 mm BL . Thereafter, the molt increment increased exponentially. The duration of the first instar was 6–7 days. Instar duration increased with development up to approximately 2 weeks at the 20th instar (∼16 mm BL ) and then became constant. Of the 10 larvae reared individually, five metamorphosed to the puerulus stage. The entire phyllosoma life ranged from 245–326 days (mean 289.0 days), and the number of instars ranged from 22–29 (mean 26.2). Body length in the final instar ranged from 28.50–33.10 mm (mean 30.280 mm). For the phyllosoma cultured in groups, relationships between BL and wet/dry body weights ( WW / DW , mg) were expressed as exponential equations: WW  = 0.0686 BL 2.2023 and DW  = 0.0209 BL 2.1905.  相似文献   
89.
In order to investigate the possible influence of estrogenic environmental endocrine disruptors on the reproductive activity of fish in Lake Kasumigaura, plasma levels of vitellogenin (VTG), a biomarker of estrogen exposure, were measured in wild and cultured male common carp Cyprinus carpio and wild crucian carp Carassius cuvieri . Testicular histology and plasma steroid hormone levels were also examined. Fish were collected from June 1998 to August 1999. Plasma VTG levels in most fish examined were below a detection limit (40 ng/mL) throughout the sampling period, and a small amount of VTG (43.5 ng/mL–1680 ng/mL) compared to that in females was detected in some fish. Active spermatogenesis in the testis and increased levels of plasma sex steroids were observed in most of the fish examined. Thus, no marked influence of estrogenic chemicals was detected in the reproductive activity of male common carp and crucian carp in Lake Kasumigaura collected from the sampling sites in the present investigation.  相似文献   
90.
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