全文获取类型
收费全文 | 139632篇 |
免费 | 7927篇 |
国内免费 | 77篇 |
专业分类
林业 | 5751篇 |
农学 | 4842篇 |
基础科学 | 913篇 |
17984篇 | |
综合类 | 19180篇 |
农作物 | 5264篇 |
水产渔业 | 7219篇 |
畜牧兽医 | 75030篇 |
园艺 | 1868篇 |
植物保护 | 9585篇 |
出版年
2020年 | 1218篇 |
2019年 | 1463篇 |
2018年 | 2291篇 |
2017年 | 2541篇 |
2016年 | 2361篇 |
2015年 | 2050篇 |
2014年 | 2518篇 |
2013年 | 6014篇 |
2012年 | 4513篇 |
2011年 | 5365篇 |
2010年 | 3604篇 |
2009年 | 3629篇 |
2008年 | 5356篇 |
2007年 | 5152篇 |
2006年 | 4803篇 |
2005年 | 4402篇 |
2004年 | 4260篇 |
2003年 | 4316篇 |
2002年 | 3936篇 |
2001年 | 4896篇 |
2000年 | 4768篇 |
1999年 | 3850篇 |
1998年 | 1501篇 |
1997年 | 1487篇 |
1996年 | 1369篇 |
1995年 | 1634篇 |
1994年 | 1347篇 |
1993年 | 1385篇 |
1992年 | 2817篇 |
1991年 | 2960篇 |
1990年 | 2945篇 |
1989年 | 2968篇 |
1988年 | 2671篇 |
1987年 | 2653篇 |
1986年 | 2595篇 |
1985年 | 2445篇 |
1984年 | 1996篇 |
1983年 | 1745篇 |
1982年 | 1174篇 |
1979年 | 1680篇 |
1978年 | 1304篇 |
1977年 | 1150篇 |
1976年 | 1121篇 |
1975年 | 1178篇 |
1974年 | 1376篇 |
1973年 | 1464篇 |
1972年 | 1406篇 |
1971年 | 1224篇 |
1970年 | 1265篇 |
1969年 | 1158篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Navicular disease is unlikely to be a single disease. The close anatomical and functional relationships between the navicular bone, collateral sesamoidean ligament, distal sesamoidean impar ligament, deep digital flexor tendon, navicular bursa and distal interphalangeal joint result in the frequent occurrence of combinations of injuries. There are a number of different pathological processes that affect the navicular bone, which probably have different aetiopathogeneses. While there is strong evidence that biomechanical forces may result in failure of functional adaptation and excessive modelling, it is likely that each disease or injury type has a multifactorial cause. 相似文献
992.
993.
994.
Evaluation of the agar-gel immunodiffusion test in the diagnosis of canine blastomycosis 总被引:4,自引:0,他引:4
The agar-gel immunodiffusion test was used to evaluated 35 dogs with histopathologically confirmed blastomycosis and 98 dogs without blastomycosis. The test had a sensitivity of 91% and a specificity of 96%. Thirteen of the dogs treated for blastomycosis were tested at 6 to 33 months after treatment with amphotericin B. Ten of 13 dogs became seronegative and 3, though clinically normal, remained seropositive at 19, 20, and 20 months, respectively, after amphotericin treatment. 相似文献
995.
JERRY A. GREENE D.V.M. M.S. CHARLES D. KNECHT V.M.D. M.S. † ‡ 《Veterinary surgery : VS》1980,9(1):27-33
This article presents a review of hemostasis and electrosurgery. The principles of electrosurgery, including the effect on tissue, vessels, and wound healing, are presented, as are the advantages and disadvantages of its use. 相似文献
996.
Two cases of urinary bladder eversion are described in association with third-degree perineal lacerations in the mare. One case of eversion followed surgical repair of the perineal defect. The other occurred spontaneously in a 5-month postpartum mare awaiting repair of a third-degree perineal laceration. Both everted bladders contained the pelvic flexure of the large colon, and in 1 case a bladder rent allowed evisceration. Surgical intervention was required, and was successful in one case. 相似文献
997.
T. M. Campbell P. M. Lording R. H. Wrigley R. B. Lavelle 《Australian veterinary journal》1980,56(12):593-598
SUMMARY Portal vein anomaly and associated hepatic encephalopathy was diagnosed in three dogs; a 2-year-old Old English Sheep Dog, a 14-week-old Old English Sheep Dog and a 20-week-old Corgi. The common clinical changes were anorexia, vomiting, depression, weakness and ataxia. The major laboratory findings were an elevated serum alanine amino transferase activity, hypoproteinaemia, hypoalbuminaemia, prolonged retention of sulphobromophthalein, fasting and postprandial hypeoammonaemia and ammonium biurate crystalluria. Angiographic studies demonstrated the presence of a patent ductus venosus in each case. The 2 Old English Sheep Dogs were destroyed at the owners' request and the necropsy findings in each case verified the presence of a portacaval shunt and hepatic encephalopathy. The Corgi is still alive, with conservative medical management, 28 months after the onset of signs. The dog is stunted and has mild, intermittent neurological disturbances. Clinical biochemistry indicates severe hepatic insufficiency and suggests a poor long term prognosis. 相似文献
998.
999.
R A Tudor M G Papich W R Redding 《Journal of the American Veterinary Medical Association》1999,215(4):503-506
OBJECTIVE: To evaluate pharmacokinetics of once daily i.v. administration of gentamicin sulfate to adult horses that had abdominal surgery. DESIGN: Prospective study. ANIMALS: 28 adult horses that underwent abdominal surgery for colic. PROCEDURE: 14 horses were treated with each dosage of gentamicin (i.e., 6.6 or 4 mg/kg, i.v., q 24 h) and blood samples were collected for pharmacokinetic analysis. Plasma gentamicin concentrations were measured by use of a fluorescence polarization immunoassay. Pharmacokinetic analysis measured the elimination half-life, volume of distribution, and gentamicin total systemic clearance. Treatment outcome, CBC, and serum creatinine concentrations were recorded. RESULTS: 1 horse in the high-dosage group died. All other horses successfully recovered, and did not develop bacterial infection or have evidence of drug toxicosis resulting in renal injury. Mean pharmacokinetic variables for gentamicin administration at a high or low dosage (i.e., 6.6 or 4 mg/kg, i.v., q 24 h) were half-life of 1.47 and 1.61 hours, volume of distribution of 0.17 and 0.17 L/kg, and systemic clearance of 1.27 and 1.2 ml/kg/min, respectively. Mean serum creatinine concentration was 1.74 and 1.71 for the high and low dosages, respectively, and serum creatinine concentration was not correlated with gentamicin clearance. CONCLUSIONS AND CLINICAL RELEVANCE: Gentamicin administration at a dosage of 4 mg/kg, i.v., every 24 hours, will result in plasma concentrations that are adequate against susceptible bacteria with a minimum inhibitory concentration (MIC) of < or = 2.0 micrograms/ml. Gentamicin administration at a calculated dosage of 6.8 mg/kg, i.v., every 24 hours will result in optimum plasma concentrations against susceptible bacteria with a MIC of < or = 4.0 micrograms/ml. 相似文献
1000.
G R Muraguri P K Gitau M N Mwangi S K Mbogo D P Kariuki 《The Onderstepoort journal of veterinary research》1999,66(2):119-122
Appraisal of the indirect fluorescent antibody test (IFAT) and antigen enzyme linked immunosorbent assay (ELISA) serological tests as carried out to detect cattle exposed to Theileria parva at the National Veterinary Research Centre, Muguga (NVRC), Kenya is reported. Using sera from T. parva naive cattle and cattle experimentally exposed to T. parva, the two tests were appraised in terms of their sensitivity and specificity. IFAT and ELISA had the same sensitivity of 90% while ELISA had a higher specificity (90%) than IFAT (80%). A comparison was also made of the capability of the two tests to detect exposure of dairy cattle to T. parva prior to immunization against East Coast fever (ECF). The positive outcome from the IFAT was significantly higher (chi 2 = 30.36; P < 0.001) than that from the ELISA. The agreement between the two tests was low (Kappa = 0.21). The two tests indicated a higher risk of ECF in the study area than was expected. Indications are that the ELISA has been effectively adopted at NVRC. 相似文献