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   282篇
  免费   47篇
  国内免费   2篇
林业   6篇
农学   2篇
  14篇
综合类   25篇
农作物   3篇
水产渔业   3篇
畜牧兽医   267篇
园艺   1篇
植物保护   10篇
  2023年   2篇
  2021年   2篇
  2020年   3篇
  2019年   5篇
  2018年   14篇
  2017年   7篇
  2016年   13篇
  2015年   7篇
  2014年   9篇
  2013年   47篇
  2012年   14篇
  2011年   12篇
  2010年   10篇
  2009年   10篇
  2008年   8篇
  2007年   2篇
  2006年   8篇
  2005年   2篇
  2004年   3篇
  2003年   8篇
  2002年   10篇
  2001年   6篇
  2000年   4篇
  1999年   3篇
  1998年   17篇
  1997年   8篇
  1996年   13篇
  1995年   8篇
  1994年   9篇
  1993年   9篇
  1992年   7篇
  1991年   10篇
  1990年   6篇
  1989年   6篇
  1988年   7篇
  1987年   2篇
  1986年   3篇
  1974年   1篇
  1970年   1篇
  1967年   1篇
  1966年   1篇
  1964年   1篇
  1957年   1篇
  1941年   1篇
  1934年   1篇
  1926年   1篇
  1925年   1篇
  1922年   2篇
  1913年   1篇
  1912年   1篇
排序方式: 共有331条查询结果,搜索用时 31 毫秒
61.
62.
AIMS: To determine the effect of contamination of urine with 0–5% blood, varying in haematocrit and protein concentrations, on the urine protein to creatinine ratio (UPC) in dogs, and to determine whether the colour of urine can be used to aid interpretation of UPC results.

METHODS: Urine samples were collected by free catch from 18 dogs, all of which had UPC?<0.2. Venous blood samples were also collected from each dog, and the blood from each dog was added to its own urine to produce serial concentrations of 0.125–5% blood. The colour of each urine sample was recorded by two observers scoring them as either yellow, peach, orange, orange/red or red. Protein and creatinine concentrations were determined, and dipstick analysis and sediment examination was carried out on each sample. Based on colour and dipstick analysis, samples were categorised as either having microscopic, macroscopic or gross haematuria. A linear mixed model was used to examine the effect of blood contamination on UPC.

RESULTS: The uncontaminated urine of all 18 dogs had a UPC?<0.2. Adding blood to the urine samples resulted in an increase in UPC at all contamination concentrations compared to the non-contaminated urine (p<0.001). None of the 54 samples with microscopic haematuria had UPC?>0.5. For 108 samples with macroscopic haematuria the UPC was >0.5 in 21 samples (19.4 (95% CI=13.1–27.9)%), and for 54 samples with gross haematuria 39 (72 (CI=59.1–82.4)%) had a UPC?>0.5. No samples had a UPC?>2.0 unless the blood contamination was 5% and only 3/18 (17%) samples at this blood contamination concentration had a UPC?>2.0.

CONCLUSIONS AND CLINICAL RELEVANCE: This study showed that while blood contamination of ≥0.125% does increase the UPC, if the urine remains yellow (microscopic haematuria), then there is negligible chance that a UPC?>0.5 will be solely due to the added blood. In that scenario, attributing the proteinuria present to the haematuria in the sample would be inappropriate. However blood contamination that results in discolouration of the urine sample from yellow (indicating macroscopic or gross haematuria) could increase the UPC above the abnormal range and would need to be considered as a differential for the proteinuria. Thus knowledge of urine colour, even if limited to simple colour scores (yellow, discoloured, red) could be utilised to aid interpretation of the UPC in samples with haematuria.  相似文献   

63.
A cross-sectional study was undertaken (October 2010 to August 2011) to estimate the prevalence of paratuberculosis in the small ruminant dairy industries in Ontario, Canada. Blood and feces were sampled from 580 goats and 397 sheep (lactating and 2 y of age or older) that were randomly selected from 29 randomly selected dairy goat herds and 21 convenience-selected dairy sheep flocks. Fecal samples were analyzed using bacterial culture (BD BACTEC MGIT 960) and polymerase chain reaction (Tetracore); serum samples were tested with the Prionics Parachek enzyme-linked immunosorbent assay (ELISA). Using 3-test latent class Bayesian models, true farm-level prevalence was estimated to be 83.0% [95% probability interval (PI): 62.6% to 98.1%] for dairy goats and 66.8% (95% PI: 41.6% to 91.4%) for dairy sheep. The within-farm true prevalence for dairy goats was 35.2% (95% PI: 23.0% to 49.8%) and for dairy sheep was 48.3% (95% PI: 27.6% to 74.3%). These data indicate that a paratuberculosis control program for small ruminants is needed in Ontario.  相似文献   
64.
AIM: To assess the effect of sedation and local anaesthesia (LA) at disbudding, and the addition of meloxicam or ketoprofen treatment, on weight gain in dairy calves following disbudding.

METHODS: Friesian-Jersey cross calves, from four dairy farms, were enrolled when 3–6 weeks old. All calves (n=271) were disbudded by veterinary personnel and randomly assigned to six groups: 136 were disbudded without sedation or LA, of which 31 received 20 mg meloxicam S/C and 75 received 150 mg ketoprofen I/M. A further 135 were disbudded with sedation (0.25 mg/kg xylazine I/M) and LA, of which 30 also received meloxicam and 75 received ketoprofen. Calves were weighed 3 days before, and 15 and 30 days after, disbudding (Day 0). Daily weight gain was analysed using mixed models and ANOVA.

RESULTS: Complete results were obtained from 263 calves. From Day ?3 to Day 15, the growth rate of calves disbudded without pain relief (0.53 (95% CI=0.47–0.60) kg/day) was less that of calves disbudded with some form of pain relief (0.65 (95% CI=0.62–0.68) kg/d; p=0.004). There was no difference between the effect of meloxicam or ketoprofen (p=1.00). An interaction between use of sedation and LA and additional non-steroidal anti-inflammatory drugs (NSAID) meant that NSAID treatment did not increase growth rates in calves disbudded with sedation and LA but did increase growth rates for calves disbudded without pain relief (p<0.05). From Day 16 to Day 30 there was no effect of NSAID treatment on growth rate, but calves receiving LA and sedation grew faster (0.74 (95% CI=0.69–0.80) kg/day) than calves disbudded without LA and sedation (0.66 (95% CI=0.61–0.71) kg/day; p=0.018). From Day ?3 to Day 30, calves disbudded with sedation and LA grew faster (0.71 (95%CI=0.64–0.77) kg/day) than calves disbudded without sedation and LA (0.60 (95% CI=0.55–0.65) kg/day; p=0.011). However, addition of NSAID to sedation and LA made no further difference to growth rates (p=0.69).

CONCLUSIONS: Dairy calves disbudded with no pain relief had slower growth rates than calves receiving pain relief. From Day 15 to 30 calves given no pain relief, or NSAID alone, grew more slowly than those receiving sedation and LA at disbudding. The addition of NSAID treatment to sedation and LA did not further increase growth rates.

CLINICAL RELEVANCE: This study adds to the evidence that pain management when disbudding is beneficial for calf productivity as well as calf welfare.  相似文献   
65.
Treatment of Goats Infected with the Lungworm Muellerius capillaris   总被引:1,自引:1,他引:0       下载免费PDF全文
Goats naturally infected with Muellerius capillaris were treated with ivermectin subcutaneously once or twice at the rate of 200 or 300 μg/kg body wt or with fenbendazole per os twice at 15 μg/kg body wt. Goats ceased passing larvae 11 to 20 days after treatment, and except for one doe, larvae reappeared in feces 34 to 59 days after treatment. In sections of lung of ivermectin-treated goats, adult Muellerius had swollen body walls and disrupted intestinal tracts. Granulomas, some mineralized, were present. It is suggested that immature Muellerius were not destroyed by either anthelmintic and that following destruction of the adults, immature Muellerius resumed development to the adult stage and produced more first-stage larvae. Treatment of Muellerius may be more effective if repeated after approximately a 35-day interval.  相似文献   
66.
AIM: To determine the impact of sodium molybdate treatment, given weekly, on concentrations of Cu in liver, activity of liver enzymes, and weight gain over 4 weeks, in yearling bulls with elevated concentrations of Cu in liver.

METHODS: The study was carried on two commercial grazing farms in the Otago region of New Zealand in yearling Friesian bulls (n=150 on Farm A and n=49 on Farm B) with mean concentration of Cu in liver >3,000 µmol/kg fresh weight. On Day 0, all animals were weighed and half were systematically allocated to treatment with sodium molybdate (3?mg/kg liveweight on Farm A and 7?mg/kg liveweight on Farm B); the remainder received no treatment (Control). Sodium molybdate was given as a drench weekly for 4 weeks and all animals were weighed again on Day 28. Ten animals on each farm (five from each treatment group) were systematically selected for blood sampling and liver biopsies on Days 0 and 28. Samples were analysed for concentrations of Cu in plasma, vitamin B12 in serum, activities of γ–glutamyl transferase, aspartate aminotransferase and glutamate dehydrogenase in serum, and concentrations of Cu and vitamin B12 in liver. Separate multivariable linear models were used to compare the change in outcome variables between Days 0 and 28 between bulls that had been drenched with sodium molybdate or not.

RESULTS: On Farm A, mean concentrations of Cu in liver on Day 28, as a percentage of concentrations on Day 0, for the control group was 55 (95% CI=40–73)% and for the treatment group was 73 (95% CI=43–111)%. On Farm B, the equivalent mean for the control group was 75 (95% CI=42–131)% and for the treatment group was 85 (95% CI=38–134)%. The multivariable linear models indicated that the changes in concentrations of Cu in liver, activities of liver enzymes and weight gain between Days 0 and 28 did not differ between the bulls treated or not with sodium molybdate (p>0.18).

CONCLUSIONS AND CLINICAL RELEVANCE: Treatment with sodium molybdate in one bolus at weekly intervals for 4 weeks did not affect concentrations of Cu in liver, activity of liver enzymes or weight gain in animals with high concentrations of Cu liver on two farms.  相似文献   
67.
68.
We hypothesized that antioxidants in organic amendments would control the rate of their decomposition in soil, such that those with more antioxidant capacity (AOC) would have slower rates of decomposition. This has been tested using materials from an incubation experiment, in which a Vertisol had been amended with a number of organic materials. Green waste compost, wheat straw, sugarcane trash and mineral fibre had been added to the soil and incubated for different periods of up to 84 days. Decomposition had been monitored by measuring cumulative carbon dioxide emissions. One and four m NaOH extracts of soil material from the experiment were analysed for their AOC by the Trolox equivalent method. The same method was used to characterize the organic amendments and the unamended soil. AOCs of the amendments were much greater than that of the soil and therefore we expected that the AOC of amended soils would be greater than the unamended control. However, this was not generally the case. A comparison of the AOC of amended soil measured after 7 days with that calculated from the components showed that the measured values of incubated amended soils were less than the calculated ones, particularly for wheat straw and sugarcane trash amendments. This suggests that some of the extractable antioxidants in the amendments were lost or transformed during the first 7 days of incubation. In the remainder of the incubation period there was a small increase in AOC with time in 4 m NaOH extracts of the amended soils, but this was not the case for 1 m NaOH extracts. There was some evidence that amendments with larger AOCs had slower rates of decomposition, especially during the first 7 days of the incubation. Other factors may have been responsible, but C:N ratio alone could not explain the differences. The results are encouraging, but more data are required to test our hypothesis thoroughly.  相似文献   
69.
Objective Describe the presence of arrhythmias in dogs with myxomatous mitral valve disease (MMVD) and the potential association with class of heart failure and left atrial enlargement. Compare the standard electrocardiogram (ECG) with Holter monitoring for assessing heart rate (HR). Experimental procedure The study group of 36 dogs weighing less than 20 kg was divided into MMVD and no clinical signs (preclinical) or MMVD and clinical signs (clinical). A standard echocardiogram, ECG and 24-h Holter recording were obtained in all dogs. Results Minimum and mean Holter HRs were higher in the clinical group than in the preclinical group. Clinical dogs had more ventricular arrhythmias than preclinical dogs. An enlarged left atrium was associated with the presence of more supraventricular arrhythmias. Conclusions Arrhythmias are a common finding in dogs with MMVD and Holter monitoring is a reliable tool for both HR monitoring and diagnosis.  相似文献   
70.
A nasal mass in a Domestic Shorthair cat was causing facial deformity, sneezing and intermittent epistaxis. Biopsy samples obtained previously had been non-diagnostic. Computed tomography images revealed an irregular, contrast-enhancing mass occupying a large portion of the righthand side of the nasal cavity. Previously described criteria for malignancy were not present. A ventral surgical approach combined with temporary, ipsilateral, common carotid arterial occlusion provided excellent access for debulking the lesion and collecting samples for histopathology. A nasal vascular hamartoma was diagnosed and clinical signs resolved postoperatively. This is the first documentation of this abnormality in the cat. Hamartomatous abnormalities should be included on the list of differential diagnoses for feline nasal mass lesions. The prognosis for hamartomatous lesions postoperatively is good, in keeping with their limited propensity for growth after maturity.  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