全文获取类型
收费全文 | 132491篇 |
免费 | 7269篇 |
国内免费 | 93篇 |
专业分类
林业 | 5390篇 |
农学 | 4269篇 |
基础科学 | 831篇 |
17045篇 | |
综合类 | 21482篇 |
农作物 | 5394篇 |
水产渔业 | 6688篇 |
畜牧兽医 | 67971篇 |
园艺 | 1801篇 |
植物保护 | 8982篇 |
出版年
2020年 | 1177篇 |
2019年 | 1375篇 |
2018年 | 2032篇 |
2017年 | 2330篇 |
2016年 | 2096篇 |
2015年 | 1742篇 |
2014年 | 2227篇 |
2013年 | 5292篇 |
2012年 | 4116篇 |
2011年 | 5093篇 |
2010年 | 3245篇 |
2009年 | 3392篇 |
2008年 | 4971篇 |
2007年 | 4668篇 |
2006年 | 4354篇 |
2005年 | 4091篇 |
2004年 | 3850篇 |
2003年 | 3975篇 |
2002年 | 3542篇 |
2001年 | 4150篇 |
2000年 | 4253篇 |
1999年 | 3373篇 |
1998年 | 1475篇 |
1997年 | 1387篇 |
1996年 | 1289篇 |
1995年 | 1531篇 |
1994年 | 1358篇 |
1993年 | 1232篇 |
1992年 | 2584篇 |
1991年 | 2700篇 |
1990年 | 2591篇 |
1989年 | 2611篇 |
1988年 | 2368篇 |
1987年 | 2348篇 |
1986年 | 2427篇 |
1985年 | 2340篇 |
1984年 | 1881篇 |
1983年 | 1677篇 |
1982年 | 1149篇 |
1979年 | 1748篇 |
1978年 | 1397篇 |
1977年 | 1152篇 |
1976年 | 1212篇 |
1975年 | 1292篇 |
1974年 | 1500篇 |
1973年 | 1514篇 |
1972年 | 1405篇 |
1971年 | 1304篇 |
1970年 | 1251篇 |
1969年 | 1283篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Canola PA Perotta JH Laskoski LM Escobar A Melo e Silva CA Canola JC Johnson PJ Valadão CA 《Equine veterinary journal》2011,43(4):446-450
Reasons for performing study: Standing surgical procedures are being employed to an ever‐greater extent in horses. Pneumoperitoneum during abdominal surgery might adversely affect the work of breathing. Objectives: To determine whether development of pneumoperitoneum during abdominal surgery adversely influences the work of breathing. Methods: Eight healthy mature horses were equipped with carotid artery and thoracic vena cava catheters and an intraluminal manometry system. The following measurements were obtained before and at +5, +10, +15 and +30 min following establishment of pneumoperitoneum by paralumbar puncture using an 8 gauge needle: vital signs, oesophageal pressure, gastric pressure, arterial and central venous blood pressures, and arterial and mixed venous blood gas analyses. Results: Significant changes in oesophageal pressure, central venous pressure and results of arterial and mixed venous blood gas analysis were not detected. Arterial diastolic and mean pressures and rectal temperature increased slightly (P≤0.05). Conclusions: Passive pneumoperitoneum did not adversely affect breathing mechanics or haemodynamic variables under experimental conditions. Changes in arterial pressure could have occurred as a response to the passive pneumoperitoneum or be related to handling stress. Subtle variations in rectal temperature were not clinically relevant and likely resulted from stress associated with restraint. Potential relevance: It is unlikely that mature horses will develop signs of respiratory difficulty as a result of the development of passive pneumoperitoneum during standing laparoscopy. 相似文献
992.
Abattoir data collected from three British pig health monitoring schemes were combined to investigate the associations between Salmonella infection and the presence of gross lesions detected in slaughtered pigs. Each set of results was linked back to the farm from which the pigs were submitted, and the Salmonella results and lesions reports were connected at farm level. Salmonella infection was determined through meat juice ELISA (MJE), and the health conditions were assessed by postmortem inspection. The final dataset contained 873 slapmarks, with an average of 215 samples tested by MJE, and 355 pigs that were assessed for health conditions, per slapmark. Each of the health assessment conditions was individually analysed by regression models to investigate associations with the MJE results, accounting for clustering at the slapmark level and also for seasonality. A multivariable model was also used to estimate the strength of association with MJE results when all the health conditions were entered into the model. The results showed positive associations between Salmonella and enzootic pneumonia-like lesions, milk spots, peritonitis and pericarditis. 相似文献
993.
994.
995.
V. Albanese B. Credille A. Ellis L. Baldwin P. O. E. Mueller A. Woolums 《Equine Veterinary Education》2011,23(6):281-285
The purpose of this report is to describe the clinical course and pathological findings in a horse admitted to the emergency service of the University of Georgia Large Animal Teaching Hospital for evaluation of colic, fever and diarrhoea of several days' duration. A presumptive historical diagnosis of colitis was made initially, but, due to the lack of faecal output during the first 12 h of hospitalisation and subsequent examination findings, an impaction of the ascending colon was suspected. Initial therapy consisted of rehydration with oral fluids and management of the abdominal pain with analgesic therapy. The horse did not respond to medical therapy and because of signs of persistent abdominal pain and financial constraints, the owner elected euthanasia after several days of supportive care. At necropsy, the horse was diagnosed with a colocolic intussusception. 相似文献
996.
R. Vivancos D. Showell B. Keeble S. Goh M. Kroese A. Lipp J. Battersby 《Zoonoses and public health》2011,58(2):126-130
Avian influenza is a highly infectious disease in poultry and although the risk of human infection is low, concerns exist that it could evolve into a new human strain of pandemic potential if reassortment with a human influenza virus occurs. In January 2007, the UK government introduced a programme to vaccinate poultry workers to reduce the potential of such an event. This study evaluates the delivery, uptake and costs of the programme in three counties of England. A questionnaire survey was completed by consultants in public health in all the Primary Care Trusts in Norfolk, Suffolk and Cambridgeshire in May 2007. The delivery of the programme varied between Primary Care Trusts, including being delivered in some cases by clinics in primary care, by general practitioners and occupational health services in others. The uptake of vaccination was low ranging from 7% to 29% at a cost of £29 to £132 per person vaccinated. Vaccination of poultry workers as a public health measure to prevent an influenza pandemic is likely to be ineffective with the level of coverage found in this evaluation in our region. 相似文献
997.
Summary Rabies incidence is high in the State of Morelos, Mexico. The present study is based on the data obtained from relevant Government institutions. The results from 1980 to 1990 show an average of 3·3 human, and from 1985 to 1990 a total of 3,173 animal rabies positive reports. It was concluded that the anti-rabies programme in Mexico, particularly in the State of Morelos, has not produced adequate results.
Rabia En El Estado De Morelos, Mexico
Resumen La rabia tiene una alta incidencia en el estado de Morelos, México. El presente estudio está basado en datos obtenidos de instituciones del Gobierno. Los datos de 1980 a 1990 indican una media anual de 3·3 casos de rabia en personas y los datos de 1985 a 1990 muestran un total de 3173 casos de rabia en animales. Se concluyó que el programa de control de rabia en Mexico, particularmente en el estado de Morelos, no ha dado resultados satisfactorios.
La Rage Dans L'etat De Moralos, Au Mexique
Résumé L'incidence de la rage est élevée dans l'Etat de Morelos, en Mexique. L'étude est basée sur des données obtenues d'institutions gouvernementales appropriées. De 1980 à 1990, on a noté une moyenne de 3,3 cas humains et de 1985 à 1990 un total de 3173 cas de rage animale. On en conclut que le programme antiabique en Mexique, en particulier dans l'Etat de Morelos, n'a pas produit de résultats satisfaisants.相似文献
998.
999.
RODNEY S. BAGLEY DVM TIMOTHY V. BASZLER DVM PhD MICHAEL L. HARRINGTON DVM G. ELIZABETH PLUHAR DVM MS MICHAEL P. MOORE DVM MS ROBERT D. KEEGAN DVM STEPHEN A. GREENE DVM MS 《Veterinary surgery : VS》1995,24(2):122-127
Longitudinal division of the corpus callosum was performed in six normal beagles to determine surgical morbidity. The corpus callosum was divided sagittally on the midline and the effect on neurological function was determined. Five of six dogs were clinically normal within 14 days or less after surgery. One dog had persistent but improving clinical signs consistent with a forebrain disturbance at 30 days after surgery. Overall, minimal morbidity and no mortality was associated with this surgical procedure. Further study is indicated to determine the efficacy of this surgical treatment for seizure control in dogs with idiopathic epilepsy. 相似文献
1000.
ROGER B. FINGLAND DVM MS Diplomate ACVS CANDACE I. LAYTON DVM MS Diplomate ACVS GEORGE A. KENNEDY DVM PhD Diplomate ACVP JOHN C. GALLAND PhD 《Veterinary surgery : VS》1995,24(4):320-330
Two suture techniques for tracheal anastomosis after large-segment tracheal resection were compared. Eight cartilages were resected from the trachea of each of 12 dogs; anastomoses with 4-0 polydioxanone suture were created using a simple continuous suture technique in six dogs and a simple interrupted suture technique in six dogs. Surgical time was shorter but apposition of tracheal segments at the time of surgery was less precise with the simple continuous suture technique. The dogs were evaluated for 150 days after surgery. Clinical abnormalities after tracheal resection and anastomosis were not observed. Percent dorsoventral luminal stenosis was calculated by measuring the tracheal lumen diameter on lateral cervical radiographs. Percent luminal stenosis was calculated planimetrically using a computerized digitizing tablet. Anastomotic stenosis was mild in all dogs; however, the mean percent luminal stenosis determined planimetrically was significantly greater for dogs that had the simple continuous suture technique. Planimetric measurements of cross-sectional area made before and after formalin fixation were not significantly different. Radiographic determination of percent dorsoventral luminal stenosis was a poor predictor of diminution of cross-sectional area determined planimetrically. 相似文献