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   1138篇
  免费   166篇
  国内免费   23篇
林业   1篇
农学   7篇
  6篇
综合类   97篇
农作物   3篇
水产渔业   20篇
畜牧兽医   1192篇
植物保护   1篇
  2024年   1篇
  2023年   16篇
  2022年   55篇
  2021年   38篇
  2020年   26篇
  2019年   32篇
  2018年   57篇
  2017年   87篇
  2016年   52篇
  2015年   76篇
  2014年   111篇
  2013年   80篇
  2012年   56篇
  2011年   89篇
  2010年   64篇
  2009年   82篇
  2008年   70篇
  2007年   69篇
  2006年   58篇
  2005年   39篇
  2004年   30篇
  2003年   24篇
  2002年   23篇
  2001年   14篇
  2000年   17篇
  1999年   21篇
  1998年   7篇
  1997年   7篇
  1996年   5篇
  1995年   6篇
  1994年   3篇
  1993年   7篇
  1992年   1篇
  1987年   1篇
  1982年   1篇
  1978年   1篇
  1977年   1篇
排序方式: 共有1327条查询结果,搜索用时 15 毫秒
991.
为快速检测犬细小病毒(CPV)、犬冠状病毒(CCV)和贾第鞭毛虫(Giardia),研究利用胶体金免疫层析技术制备CPV+CCV+Giardia抗原三合一胶体金检测卡并评价其各项指标.结果显示,该三合一胶体金检测卡与CDV、CPV、CAV、CRV、CCV和Giardia(自身样本除外)无交叉反应;可检测浓度低至10.0...  相似文献   
992.
The recommended treatment for canine ehrlichiosis is tetracycline or its analog doxycycline, although recent reports have documented ineffective clearing of Erchlichia canis after doxycycline administration. Imidocarb dipropionate is used as an alternative treatment to tetracycline or is used in conjunction with doxycycline. The effectiveness of imidocarb dipropionate in clearing Ehrlichia species from the blood and tissues of dogs with E. canis infection has not been thoroughly evaluated. Fifteen dogs were experimentally infected with E. canis. Ten dogs were treated with imidocarb dipropionate (6.6 mg/kg, IM, 2 injections given 2 weeks apart). Five infected control dogs were not treated. Blood samples from all 15 dogs were E. canis DNA positive by PCR assay by 3 weeks after inoculation (PI), and E. canis antibodies were detected by IFA assay by 1 week PI. Blood platelet counts in all dogs were below the reference interval by 4 weeks PI. E. canis DNA was detected in bone marrow and splenic aspirates by PCR assay 4 weeks PI but not before infection. Bone marrow aspirates were E. canis DNA positive by PCR assay in 14/15 dogs, and splenic aspirates were E. canis DNA positive by PCR assay in 13/15 dogs. Blood samples from all treated and control dogs remained positive for E. canis DNA by PCR assay, and platelet counts remained below preinoculation values 13 weeks PI (6 weeks after 2nd treatment). As administered in this study, imidocarb dipropionate did not clear experimental E. canis infection in dogs.  相似文献   
993.
A 12‐year‐old spayed female miniature Poodle presented for coughing, respiratory distress, and anorexia. After thoracentesis for pleural effusion, radiography revealed an enlarged cardiac silhouette with a bulge in the area of the body of the right atrium. Echocardiography revealed an anechoic chamber‐like cavity lateral to the right atrium that communicated with the right atrium through a 13 mm defect in the right atrial free wall. Contrast echocardiography and color flow Doppler were used to prove that the cavity communicated with the right atrium. The cavity was diagnosed as a giant right atrial diverticulum.  相似文献   
994.
Background: Choroid plexus tumors (CPTs) comprise approximately 10% of all primary brain tumors in dogs. The clinical utility of magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) analysis, or both in the presumptive diagnosis of CPTs has not been determined.
Objectives: To report MRI and CSF findings in dogs with CPT and determine if there are distinguishing features that allow clinical discrimination between the tumor grades.
Animals: Fifty-six client-owned dogs with naturally occurring CPT.
Methods: Retrospective case series. The inclusion criterion was histologically confirmed CPT. Blinded review of cranial MRI and cisternal CSF analysis was performed.
Results: Thirty-six of 56 dogs had a choroid plexus carcinoma (CPC) and 20 had a choroid plexus papilloma (CPP). Golden Retrievers were overrepresented compared with the hospital population (frequency 3.7 times that expected, confidence interval 95%= 2.0–6.7, P < .0002). Median CSF protein concentration in CPCs (108 mg/dL, range 27–380 mg/dL) was significantly higher than in CPPs (34 mg/dL, range 32–80 mg/dL) ( P = .002). Only dogs with CPCs had a CSF protein concentration >80 mg/dL. Cytological evidence of malignancy in CSF was seen in 7 of 15 CPCs. Only CPCs had evidence of intraventricular or subarachnoid metastases on MRI.
Conclusions and Clinical Importance: MRI, CSF analysis or both can help to differentiate between CPPs and CPCs, and may provide valuable prognostic and pretreatment information.  相似文献   
995.
A 5-year-old male English Bulldog was presented with a 1-year history of paroxysmal supraventricular tachycardia (SVT) partially responsive to amiodarone. At admission the surface ECG showed sustained runs of a narrow QRS complex tachycardia, with a ventricular cycle length (R–R interval) of 260 ms, alternating with periods of sinus rhythm. Endocardial mapping identified the electrogenic mechanism of the SVT as a circus movement tachycardia with retrograde and decremental conduction along a concealed postero-septal atrioventricular pathway (AP) and anterograde conduction along the atrioventricular node. These characteristics were indicative of a permanent junctional reciprocating tachycardia (PJRT). Radiofrequency catheter ablation of the AP successfully terminated the PJRT, with no recurrence of tachycardia on Holter monitoring at 12 months follow-up.  相似文献   
996.
为获得高亲和力抗犬细小病毒单链抗体,构建抗犬细小病毒(CPV)细菌展示单链抗体文库。研究提取犬脾脏总RNA,反转录c DNA,以此为模板,分别扩增犬抗体VH和VL编码序列,插入克隆载体p Tlinker。利用SfiⅠ酶切位点将sc Fv基因构建至细菌展示载体p BSD中,将重组质粒电转化入E.coli DH5α构建p BFD-sc Fv细菌展示库。通过标记FITC的VP2蛋白,利用流式细胞术筛选12株阳性sc Fv。将12株sc Fv基因分别插入p ET-28a,构建重组表达质粒p ET28a-sc Fv。转化到E.coli Rosetta中诱导表达,获得约28 ku目的蛋白。经ELISA检测,纯化sc Fv对VP2蛋白P/N值均大于2.1,其中sc Fv-23、sc Fv-33、sc Fv-34对VP2蛋白亲和力较强。研究通过免疫本动物源动物,在获得高价抗体同时,避免传统单克隆抗体的免疫排斥现象;结合流式细胞术和细菌展示技术可对单链抗体文库高效、快速筛选。抗犬细小病毒同源单链抗体研究在填补市场同源基因工程抗体空白的同时,可为研制具有中和活性全长抗体奠定基础。  相似文献   
997.
AIM: To estimate the heritability of the New Zealand Veterinary Association (NZVA) elbow phenotype, obtain estimated breeding values (EBV) for the worst-elbow score and estimate the genetic trends for this trait in four populous breeds of dogs, using the records from the NZVA Canine Elbow Dysplasia Scheme database (1992–2013).

METHODS: Overall, 4,070 elbow records from a pedigree of 11,311 dogs were available for animals scored between 1992 and 2013. The worst elbow score between the left and right elbows was identified for each dog and used for EBV analysis. Estimates of heritability and EBV for the elbow score of dogs from German Shepherd dog, Labrador Retriever, Golden Retriever and Rottweiler breeds were obtained using restricted maximum likelihood procedures with a within-breed linear animal model. The model included the fixed effects of sex and birth year, with age at scoring as a covariable, and the random effect of animal. Genetic trends for the worst-elbow score were calculated as the regression coefficient of the EBV, weighted by reliabilities, on year of birth.

RESULTS: The estimates of heritability for worst-elbow score were 0.25 (SE 0.06) in German Shepherd dogs, 0.46 (SE 0.06) in Labrador Retrievers, 0.18 (SE 0.07) in Golden Retrievers and 0.29 (SE 0.11) in Rottweilers. The genetic trend for German Shepherd dogs was ?0.0082 (SE 0.0015), for Labrador Retrievers was ?0.0016 (SE 0.0016), for Golden Retrievers was ?0.0033 (SE 0.0010) and for Rottweilers was ?0.0070 (SE 0.0023) units per annum, which were different from zero (p<0.01) in all breeds except Labrador Retrievers.

CONCLUSIONS AND CLINICAL RELEVANCE: A small but favourable response to selection was achieved by three of the four breeds in the study period; during which selection for elbow traits has been largely voluntary. While the magnitude of genetic change in terms of elbow units per annum may appear small, it must be remembered that elbow scoring grades only range from 0–3. Greater improvement may be possible if compulsory screening was a requirement for pedigree breeding stock, and if greater selection pressure were applied on the basis on an individual’s EBV, rather than the worst-elbow score alone. The maintenance of an open registry, with transparency of EBV information made available to all breeders, may enhance selection intensity opportunities and potentially assist with the process and progress of breeding selection.  相似文献   
998.
以新分离的两种不同亚型CPV为毒种制备浓缩灭活苗和未浓缩灭活苗,通过与商品化弱毒苗的比较评价灭活疫苗的免疫效果。将CPV-S5(New CPV-2a)与CPV-1401(New CPV-2b)毒株扩大培养后浓缩灭活,制备了两种浓缩与两种未浓缩水溶剂灭活疫苗;将灭活疫苗和商品化二联弱毒苗分别接种5周龄HI阴性幼犬,分别在免疫后7 d、14 d、21 d、28 d测定HI抗体效价;首免36 d后取其中4只犬二免,其他犬进行攻毒。结果显示,各免疫组在第7天HI均高于1∶80,浓缩组显著高于未浓缩组,初步表明CPV灭活苗效果与抗原的浓度有直接的关系;灭活疫苗组与商品化弱毒苗组均差异显著;免疫组的犬均存活,而HI阴性犬死亡,经检测死亡犬CPV为阳性,表明制备的CPV灭活苗产生的特异性免疫应答均能抵抗强毒的攻击,对犬起到良好的免疫保护;二免后其HI抗体效价极显著提高,有效抗体能维持5个月,更有效的对免疫犬群进行保护。  相似文献   
999.

Objectives

To evaluate tricuspid annular plane systolic excursion (TAPSE) in dogs with myxomatous mitral valve disease (MMVD) with or without pulmonary hypertension (PH) and to study the correlations with clinical and echocardiographic parameters.

Animals

The study population included 99 dogs with MMVD and tricuspid regurgitation.

Methods

This is a prospective clinical study. All dogs received a transthoracic echocardiographic evaluation, including 2D, M-mode, echo-Doppler, and tissue Doppler measurements. The TAPSE was measured from the left apical four-chamber view and normalized for the effect of body weight (nTAPSE). The dogs were grouped according to the severity of MMVD (American College of Veterinary Internal Medicine guidelines) and presence/absence and severity of PH. Significant differences between TAPSE or nTAPSE and echocardiographic parameters were analyzed among the MMVD and PH severity groups. Correlations between TAPSE or nTAPSE and echocardiographic parameters were calculated.

Results

Tricuspid annular plane systolic excursion or nTAPSE were not significantly different among dogs of the MMVD or PH severity groups. Significant correlations were obtained between TAPSE and body weight, left ventricular and atrial dimensions, early diastolic septal and early diastolic and systolic tricuspid annulus velocity (p<0.001); nTAPSE was significantly correlated with normalized end-diastolic left ventricular dimension and fractional shortening (p<0.001).

Conclusions

The results show that neither TAPSE nor nTAPSE are reduced in dogs with MMVD with or without PH. It remains unclear if the right ventricle function is not reduced or if a reduced right ventricle function is masked by the contraction of the left ventricle through ventricular interdependence.  相似文献   
1000.
We evaluated the long-term effect of early angiotensin-converting enzyme (ACE) inhibition (enalapril maleate) as monotherapy to postpone or prevent congestive heart failure (CHF) in asymptomatic dogs with mitral regurgitation (MR) attributable to myxomatous valvular disease (MVD) in a prospective, randomized, double-blinded, placebo-controlled multicenter trial involving 14 centers in Scandinavia. Two hundred twenty-nine Cavalier King Charles (CKC) Spaniels with MR attributable to MVD but no signs of CHF were randomly allocated to treatment with enalapril 0.25-0.5 mg daily (n = 116) or to placebo groups (n = 113). Each dog was evaluated by physical examination, electrocardiography, and thoracic radiography at entry and every 12 months (+/-30 days). The number of dogs developing heart failure was similar in the treatment and placebo groups (n = 50 [43%] and n = 48 [42%], respectively; P = .99). The estimated means, adjusted for censored observations, for the period from initiation of therapy to heart failure were 1,150 +/- 50 days for dogs in the treatment group and 1,130 +/- 50 days for dogs in the placebo group (P = .85). When absence or presence of cardiomegaly at the entrance of the trial was considered, there were still no differences between the treatment and placebo groups (P = .98 and .51, respectively). Multivariate analysis showed that enalapril had no significant effect on the time from initiation of therapy to heart failure (P = .86). Long-term treatment with enalapril in asymptomatic dogs with MVD and MR did not delay the onset of heart failure regardless of whether or not cardiomegaly was present at initiation of the study.  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