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   103篇
  免费   23篇
林业   6篇
农学   1篇
  9篇
综合类   8篇
农作物   1篇
畜牧兽医   98篇
植物保护   3篇
  2023年   1篇
  2022年   1篇
  2021年   2篇
  2020年   3篇
  2018年   10篇
  2017年   6篇
  2016年   7篇
  2015年   3篇
  2014年   6篇
  2013年   9篇
  2012年   1篇
  2011年   3篇
  2010年   9篇
  2009年   5篇
  2008年   5篇
  2007年   3篇
  2006年   3篇
  2005年   4篇
  2004年   7篇
  2003年   4篇
  2002年   2篇
  2001年   3篇
  2000年   3篇
  1998年   6篇
  1997年   4篇
  1996年   2篇
  1995年   1篇
  1994年   2篇
  1991年   2篇
  1990年   4篇
  1989年   1篇
  1984年   2篇
  1981年   1篇
  1974年   1篇
排序方式: 共有126条查询结果,搜索用时 0 毫秒
101.
Zoospore suspensions ofPhytophthora infestans applied to potato cultivars in the field with an exponential inoculum sprayer resulted in defoliation within a range of severity that was log-normal with respect to inoculum concentration. Regression lines for different cultivars differed in position and, depending upon moisture conditions, slope, indicating that the cultivars differed in resistance to penetration and to invasion of tissue by the pathogen.  相似文献   
102.
Glycerol is used as a bovine semen osmotic cryoprotectant that greatly improves the quality of frozen and thawed bovine sperm. However, high glycerol concentrations can have a toxic effect on frozen and thawed bovine sperm. Therefore, this experiment investigated the effect of replacing a portion of the glycerol in a cryoprotectant solution with crocin on the sperm apoptosis, protamine deficiency and membrane lipid oxidation of frozen and thawed Yanbian yellow cattle sperm. The experiment included a control group (6% glycerol) and four treatment groups: I (3% glycerol), II (3% glycerol +0.5 mM crocin), III (3% glycerol + 1 mM crocin) and IV (3% glycerol + 2 mM crocin). Computer assisted semen analysis was used to detect sperm motility, Hoechst 33,342, propidium iodide, and JC-1 staining were used to analyse sperm viability and mitochondrial membrane potential, chromomycin A3 staining was used to detect protamine deficiency and DNA damage, flow cytometry was used for sperm membrane lipid disorder detection and analysis, and real-time quantitative RT-qPCR was used to detect the mRNA expression levels of protamine-related genes (PRM2, PRM3), sperm acrosome-associated genes (SPACA3), oxidative stress-related genes (ROMO1) and apoptosis-related genes (BCL2, BAX). Compared to the control group, replacing a portion of glycerol with 1 mM crocin significantly improved sperm motility, plasma membrane integrity, membrane lipid disorders (p < .05) and viability, mitochondrial membrane potential, protamine deficiency (p < .01). The expression level of PRM2, PRM3, SPACA3 and BCL2 significantly increased (p < .05), while the expression levels of ROMO1 and BAX significantly decreased (p < .05). Accordingly, the BCL2/BAX ratio significantly increased (p < .05). In summary, the substitution of a portion of glycerol with crocin in cryoprotective solution improved the quality of Yanbian yellow cattle sperm after freezing and thawing.  相似文献   
103.
CASE HISTORY: A 6-year-old, spayed, female, domestic short-haired cat presented with severe erythroderma and scaling skin. She showed disturbed gait and mild behavioural changes.

CLINICAL FINDINGS: The cat had a generalised, erythematous, scurfy dermatitis with marked, multifocal crusting and skin thickening. The skin was painful and contracted, which appeared to prevent normal freedom of movement.

DIAGNOSIS: The cat was suspected to have a paraneoplastic syndrome. A mediastinal mass was located and histologically confirmed as thymoma. The cat was diagnosed with a thymoma-associated cutaneous paraneoplastic syndrome.

CLINICAL RELEVANCE: This is a rare condition with few reports in the literature. The skin changes, both grossly and histologically, were considered to be different from those described in cases of paraneoplastic dermatosis associated with pancreatic neoplasia. The clinical presentation was characteristic and more cases may occur in practice than are recognised. In this case, as in previous reports, the tumour was grossly resectable, which could lead to cure of the clinical condition.  相似文献   
104.
105.
The mare exhibits nocturnal uterine contractions in the last 6 days of gestation. It is hypothesized that estradiol 17β (O17β) may be associated with the nightly increase in uterine contractions. The 24‐h secretion pattern of plasma O17β was measured in 3 pony mares in late gestation to identify changes in release as the mare neared parturition. Blood was collected weekly at 08:00 hours beginning on day 240 and every third day from day 330 until delivery. Serial blood samples were collected from each mare every 30‐min for 24‐h beginning on gestation day 310 and every sixth day thereafter until parturition. Concentrations of O17β were elevated at night with lowest concentrations occurring directly before sunset (p < 0.01). The natural log of the variance was increased at sunset (p < 0.01) and was decreased during the 6‐h period immediately after sunrise. This pattern was especially evident in the 6 days that preceded parturition. The contrast between nocturnal and daytime concentrations of O17β in the last 6 days of gestation may contribute to night‐time delivery in the mare.  相似文献   
106.
Reproductive management of male donkeys employed for artificial breeding has been poorly studied. The aim of this study was to evaluate the effect of housing system, with the animals grouped together in a paddock or kept in individual boxes, on sexual behaviour, cortisol and testosterone concentration and seminal characteristics of adult male donkeys. The study included four Amiata donkey jacks (stallions) from which ejaculates, saliva and blood were collected during two distinct 3 weeks periods, one in the group and one in the box housing system. Time needed for semen collection was shorter when donkeys were kept in paddocks compared to when they were kept in single boxes (14:57 ± 07:27 and 20:52 ± 09:31 min, p < .05). Native semen characteristics were not influenced by housing system, while cooled preservation in an Equitainer® showed that sperm motility parameters were significantly higher during the paddock period compared to the box period. Salivary cortisol was influenced by housing system, both before and 60 min after ejaculation, being statistically higher when donkeys were housed in paddocks. On the contrary, overall and basal testosterone concentrations were significantly higher when animals were kept in boxes. In conclusion, in the present study, good quality semen could be successfully collected from donkeys irrespective of the housing system despite some differences in hormone concentrations.  相似文献   
107.
This study examined the effect of acute bull exposure around the time of artificial insemination (AI) on oxytocin and progesterone concentrations, and pregnancy rates in dairy cows. Ninety six dairy cows, stratified according to parity into primiparous and pluriparous, were divided into three groups; short bull exposure (SBE; 10 min, n = 32), long bull exposure (LBE; 4 h, n = 32) or no bull exposure (NBE; n = 32). On day 45 post‐partum, all cows were treated with PGF2α on three occasions 11–14 days apart to synchronize oestrus. They were submitted to fixed time AI 80 h after the third PGF2α injection. Cows in the SBE and LBE groups were artificially inseminated 5 min after the introduction of the bull. From a subset of cows (n = 6 per group; three primiparous and three pluriparous), blood samples were collected once every 5 min starting 15 min before AI until 15 min after AI and analysed for oxytocin concentrations. Additional blood samples were collected for measurements of progesterone (P4) concentrations once daily for 4 days starting on the day of AI and once every 3 days thereafter until day 22. The effects of bull exposure, time, parity, difficulty of AI, and pregnancy on oxytocin and P4 concentrations were analysed using the mixed linear model procedure. Mean oxytocin concentrations or change in oxytocin concentrations after bull exposure or AI were not different among groups. Pregnancy rates for the NBE, SBE and LBE groups were 55.5%, 33.3% and 44.4%, respectively, and were not different among groups. In conclusion, acute bull exposure around the time of AI did not affect oxytocin and progesterone concentrations and did not improve pregnancy rates in dairy cattle under these farms conditions.  相似文献   
108.
OBJECTIVE: To determine intraocular pressure (IOP) in cats > or = 7 years of age undergoing a routine comprehensive geriatric health examination. DESIGN: Prospective study. ANIMALS: 538 cats (1,068 eyes). PROCEDURE: IOP was measured by applanation tonometry following instillation of 0.5% proparacaine. RESULTS: Mean +/- SD IOP for all eyes was 12.3 +/- 4.0 mm Hg (range, 4 to 31 mm Hg). Mean age was 12.3 +/- 2.9 years. Intraocular pressure did not vary significantly cross-sectionally with age. However, in 78 cats, IOP was measured more than once, and follow-up measurements were significantly less than initial measurements (mean time between measurements, 9.4 +/- 3.0 months). The most useful tonometric criteria for identifying ocular abnormalities on the basis of IOP was an IOP > or = 25 mm Hg (mean + 3 SD) or a difference in IOP between eyes > or = 12 mm Hg. Eight cats met these criteria, and 5 of these cats had ophthalmic abnormalities. Low IOP was a nonspecific indicator of the presence of ocular abnormalities, as 111 cats had an IOP < or = 8 mm Hg, but only 2 had uveitis. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that IOP measurements can be a useful addition to a comprehensive geriatric health examination in cats > or = 7 years of age, especially when combined with an ophthalmic examination. Cats without ocular abnormalities that have lOP > or = 25 mm Hg or a > or = 12 mm Hg difference in IOP between eyes should have tonometry repeated or be referred to an ophthalmologist for further evaluation before beginning antiglaucoma treatment.  相似文献   
109.
The finding of Alzheimer type II astrocytes, in addition to the pathognomonic combination of laminar cerebrocortical necrosis and eosinophil infiltration, in the brains of pigs is reported for the first time in cases of indirect salt poisoning following water deprivation.  相似文献   
110.
Studies were conducted under experimental and field conditions to determine the effect of infection with M. hyopneumoniae on the immune response in serum as measured by ELISA. Following intratracheal challenge or contact exposure, serologically negative pigs derived from mycoplasma-free piggeries developed an immune response within 10 days. This response continued to rise for a further 50 days. In a field study in a commercial piggery, no animals (0/44) were observed to have M. hyopneumoniae antibodies at day 86 of life. However between day 86 and day 144, 97.7% (42/43) animals sero-converted. These results are discussed in terms of infection spread, particularly in the grower/finisher shed.  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