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   480篇
  免费   46篇
林业   11篇
农学   7篇
基础科学   3篇
  56篇
综合类   30篇
农作物   11篇
水产渔业   37篇
畜牧兽医   348篇
园艺   8篇
植物保护   15篇
  2024年   3篇
  2023年   18篇
  2022年   12篇
  2021年   22篇
  2020年   14篇
  2019年   23篇
  2018年   21篇
  2017年   21篇
  2016年   12篇
  2015年   16篇
  2014年   27篇
  2013年   13篇
  2012年   32篇
  2011年   34篇
  2010年   18篇
  2009年   13篇
  2008年   24篇
  2007年   20篇
  2006年   20篇
  2005年   37篇
  2004年   33篇
  2003年   35篇
  2002年   39篇
  2001年   4篇
  2000年   2篇
  1998年   1篇
  1997年   3篇
  1996年   3篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1983年   1篇
  1888年   1篇
排序方式: 共有526条查询结果,搜索用时 31 毫秒
61.
Risk-based surveillance is becoming increasingly important in the veterinary and public health fields. It serves as a means of increasing surveillance sensitivity and improving cost-effectiveness in an increasingly resource-limited environment. Our approach for developing a tool for the risk-based geographical surveillance of contagious diseases of swine incorporates information about animal density and external biosecurity practices within swine herds in southern Ontario. The objectives of this study were to group the sample of herds into discrete biosecurity groups, to develop a map of southern Ontario that can be used as a tool in the risk-based geographical surveillance of contagious swine diseases, and to identify significant predictors of biosecurity group membership. A subset of external biosecurity variables was selected for 2-step cluster analysis and latent class analysis (LCA). It was determined that 4 was the best number of groups to describe the data, using both analytical approaches. The authors named these groups: i) high biosecurity herds that were open with respect to replacement animals; ii) high biosecurity herds that were closed with respect to replacement animals; iii) moderate biosecurity herds; and iv) low biosecurity herds. The risk map was developed using information about the geographic distribution of herds in the biosecurity groups, as well as the density of swine sites and of grower-finisher pigs in the study region. Finally, multinomial logistic regression identified heat production units (HPUs), number of incoming pig shipments per month, and herd type as significant predictors of biosecurity group membership. It was concluded that the ability to identify areas of high and low risk for disease may improve the success of surveillance and eradication projects.  相似文献   
62.
As a result of the growing need for public-health veterinarians, novel educational programs are essential to train future public-health professionals. The University of Minnesota School of Public Health, in collaboration with the College of Veterinary Medicine, initiated a dual DVM/MPH program in 2002. This program provides flexibility by combining distance learning and on-campus courses offered through a summer public-health institute. MPH requirements are completed through core courses, elective courses in a focus area, and an MPH project and field experience. Currently, more than 100 students representing 13 veterinary schools are enrolled in the program. The majority of initial program graduates have pursued public-practice careers upon completion of the program. Strengths of the Minnesota program design include accessibility and an environment to support multidisciplinary training. Continued assessment of program graduates will allow for evaluation and adjustment of the program in the coming years.  相似文献   
63.
Objective— To report the diagnosis and treatment of a branchial apparatus anomaly (BAA) associated with a mandibular malformation in a foal.
Design— Clinical report.
Animal— Haflinger foal.
Methods— A 6-day-old foal had a fluctuating cystic mass in the pharyngeal (throatlatch) region, which changed in appearance after ingestion of milk. Upper airway endoscopy and diagnostic imaging (ultrasonography, radiography, computed tomography) permitted identification of the anatomic location of a communicating tract between the lumen of the cystic mass and the pharynx. The mass was surgically removed and communication with the pharynx ligated. Histologic appearance of this mass was consistent with a branchial cyst or sinus. The mandibular malformation was managed conservatively.
Results— Surgical resection of a third branchial sinus resulted in an excellent functional and cosmetic outcome. There was no evidence of any mandibular deformity 2 years later.
Conclusion— BAA may induce secondary mandibular deformation in utero and may cause respiratory compromise postpartum. Careful surgical dissection and removal of BAA resulted in an excellent outcome.
Clinical Relevance— BAAs should be included in the differential diagnosis of a throatlatch region mass in equine neonates. Complete surgical excision is recommended and full recovery of any associated mandibular deformity may be anticipated without additional treatment in very young patients.  相似文献   
64.
65.
Background: Low‐molecular‐weight heparin (LMWH) is being used increasingly in veterinary medicine for both treatment and prophylaxis of thromboembolic disease, but no predictable patient‐side method exists to monitor its effect. Objectives: The aim of this study was to evaluate thromboelastography (TEG) and prothombinase‐induced clotting time (PiCT) assays for detecting hemostatic alterations following in vitro heparinization of canine whole blood with dalteparin (Fragmin). Methods: Citrated whole‐blood samples were collected from 7 clinically healthy dogs. Dalteparin was added at concentrations of 0, 0.156, 0.625, 1.25, and 2.5 U/mL of whole blood. TEG was performed using heparinase cups with tissue factor (TF, 1:50,000) and kaolin as activators. Reaction time (R), clotting time (K), angle (α), and maximum amplitude (MA) were recorded. PiCT and anti‐FXa activity were measured in plasma. Results: With TF, increasing concentrations of dalteparin significantly prolonged R and K and significantly decreased α and MA. K, α, and MA ratios were significantly different from baseline at all dalteparin concentrations and R was significantly different from baseline at concentrations of 0.625, 1.25, and 2.5 U/mL. With kaolin, only R was significantly different from baseline at dalteparin concentrations of 0.625 and 2.5 U/mL. PiCT detected dalteparin concentrations ≤ 0.625 U/mL, with a good linear correlation (r2=.96, P<.0001). Conclusion: These results suggest that TF‐activated TEG and PiCT assays should be further evaluated as promising new methods for evaluating the effect of LMWH, using doses in the recommended clinical range and prospective clinical studies.  相似文献   
66.

Objective

To describe a novel ultrasound-guided posterior extraconal block in the dog.

Study design

Prospective experimental cadaveric study.

Animals

A total of 13 Beagle Cross cadaver heads.

Methods

After describing the ultrasound bony landmarks and posterior extraconal local regional technique in one head, 12 heads were used to evaluate the spreading of contrast and evaluate potential complications. A 5–8 MHz microconvex ultrasound probe was positioned caudal to the orbital ligament, with the beam orientated transversely, and then tilted caudally until the orbital fissure was visualized. After identifying the bony structures consistent with the orbital fissure, a needle was advanced using an in-plane technique and 0.5 mL of a 50:50 mixture of iohexol and methylene blue was injected. Computed tomography (CT) and dissection were used to evaluate successful injections and potential complications. The injection was considered successful if radiopaque contrast medium was 5 mm from the orbital fissure. Potential complications were defined as the presence of radiopaque contrast within the globe or the intracalvarial tissues.

Results

The CT images confirmed contrast at the target site in 15/24 (63%) of the injections. Only two injections were found in the temporalis muscle; the rest of the injections were located in the extraconal space. No potential complications such as intracranial spreading of contrast, intravascular or intraocular injection were found.

Conclusions and clinical relevance

The technique can deliver contrast close to the main nerves which provide sensory and motor innervation to the eye. Further studies are needed to evaluate this technique in clinical cases.  相似文献   
67.
68.
69.
OBJECTIVE: To evaluate the isoflurane-sparing and clinical effects of two constant rate infusions of remifentanil in healthy dogs undergoing orthopaedic surgery. STUDY DESIGN: Prospective, randomized clinical study. ANIMALS: Forty-one American Society of Anesthesiologists I-II client-owned dogs (age, 7 months-9 years; body mass 11-59 kg). METHODS: Dogs were randomly assigned to one of three groups and received either: intramuscular (IM) meperidine 2 mg kg(-1) every 2 hours throughout surgery (control group (C); n = 13); remifentanil infused intravenously (IV) at 0.1 microg kg(-1) minute(-1) (low remifentanil group (L); n = 14) or remifentanil infused at 0.25 microg kg(-1) minute(-1) IV (high remifentanil group (H); n = 14). Anaesthesia was induced with thiopental administered to effect and maintained using isoflurane in 100% oxygen. During controlled ventilation when the end-tidal CO(2) was maintained between 4.65 and 5.98 kPa [35-45 mmHg], the end-tidal isoflurane concentration (e'iso%), mean arterial blood pressure (MAP) and heart rate (HR) were measured every 5 minutes. Bradycardia (HR < 40 minute(-1) lasting >5 minutes) was corrected with 0.01 mg kg(-1) IV glycopyrrolate. Data were analysed using the Kruskal-Wallis test with a post-hoc Mann-Whitney U-test and Bonferroni correction. Statistical significance was accepted at < or = 0.05. Data are expressed as mean +/- standard deviation. RESULTS: The e'iso% was reduced in a dose-dependent manner by remifentanil. In C, e'iso% was 1.28 +/-0.13 and was significantly different from L (0.78 +/- 0.17, p < 0.001) and H (0.65 +/- 0.16, p < 0.001). HR was significantly different between groups (p < 0.001). There were no significant differences in MAP between groups. Glycopyrrolate was required in two, three and six dogs in the C, L and H groups respectively. CONCLUSIONS: Remifentanil infusion reduced the isoflurane concentration required for surgical anaesthesia during orthopaedic surgery. CLINICAL RELEVANCE: Remifentanil infusions may be a useful additive to isoflurane anaesthesia in healthy dogs.  相似文献   
70.
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