全文获取类型
收费全文 | 188378篇 |
免费 | 10162篇 |
国内免费 | 147篇 |
专业分类
林业 | 7460篇 |
农学 | 5797篇 |
基础科学 | 1221篇 |
23220篇 | |
综合类 | 32511篇 |
农作物 | 7412篇 |
水产渔业 | 9242篇 |
畜牧兽医 | 96999篇 |
园艺 | 2446篇 |
植物保护 | 12379篇 |
出版年
2019年 | 1764篇 |
2018年 | 2601篇 |
2017年 | 3018篇 |
2016年 | 2742篇 |
2015年 | 2308篇 |
2014年 | 2910篇 |
2013年 | 7338篇 |
2012年 | 5302篇 |
2011年 | 6718篇 |
2010年 | 4262篇 |
2009年 | 4454篇 |
2008年 | 6519篇 |
2007年 | 6153篇 |
2006年 | 5828篇 |
2005年 | 5371篇 |
2004年 | 5106篇 |
2003年 | 5232篇 |
2002年 | 4750篇 |
2001年 | 5773篇 |
2000年 | 5887篇 |
1999年 | 4664篇 |
1998年 | 1985篇 |
1997年 | 1933篇 |
1996年 | 1827篇 |
1995年 | 2202篇 |
1994年 | 1966篇 |
1993年 | 1830篇 |
1992年 | 3862篇 |
1991年 | 4047篇 |
1990年 | 3889篇 |
1989年 | 3889篇 |
1988年 | 3623篇 |
1987年 | 3649篇 |
1986年 | 3782篇 |
1985年 | 3641篇 |
1984年 | 2934篇 |
1983年 | 2603篇 |
1982年 | 1781篇 |
1979年 | 2744篇 |
1978年 | 2226篇 |
1977年 | 1857篇 |
1976年 | 1887篇 |
1975年 | 1999篇 |
1974年 | 2446篇 |
1973年 | 2475篇 |
1972年 | 2324篇 |
1971年 | 2173篇 |
1970年 | 2082篇 |
1969年 | 2016篇 |
1967年 | 1803篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
D Rüedi 《Berliner und Münchener tier?rztliche Wochenschrift》1991,104(3):79-83
The existence of the elephant is heavily threatened. It is of great importance--for saving our largest land mammal on earth--to research into biology of the elephant quickly and thoroughly. Keeping elephants in Zoos and circus should be improved, breeding efforts must be enhanced and veterinary treatment has to be intensified. This is imperative for all zoo veterinarians. 相似文献
992.
Cerebellar degeneration in dairy calves: clinical, pathologic, and serologic features of an epizootic caused by bovine viral diarrhea virus 总被引:1,自引:0,他引:1
T M Wilson A deLahunta L Confer 《Journal of the American Veterinary Medical Association》1983,183(5):544-547
Three of nine dairy calves born in the spring/summer wee severely ataxic at birth. Necropsy of the 3 affected calves revealed severe cerebellar degeneration (hypoplasia). Clinical signs were inapparent in the adult cows. Serum neutralization titers of the cows and calves indicated high bovine viral diarrhea titers. 相似文献
993.
994.
Genetic diversity,anti‐microbial resistance,plasmid profile and frequency of the Vi antigen in Salmonella Dublin strains isolated in Brazil 下载免费PDF全文
F. P. Vilela M. R. Frazão D. P. Rodrigues R. G. Costa M. R. T. Casas S. A. Fernandes J. P. Falcão F. Campioni 《Zoonoses and public health》2018,65(1):e34-e43
Salmonella Dublin is strongly adapted to cattle causing enteritis and/or systemic disease with high rates of mortality. However, it can be sporadically isolated from humans, usually causing serious disease, especially in patients with underlying chronic diseases. The aim of this study was to molecularly type S. Dublin strains isolated from humans and animals in Brazil to verify the diversity of these strains as well as to ascertain possible differences between strains isolated from humans and animals. Moreover, the presence of the capsular antigen Vi and the plasmid profile was characterized in addition to the anti‐microbial resistance against 15 drugs. For this reason, 113 S. Dublin strains isolated between 1983 and 2016 from humans (83) and animals (30) in Brazil were typed by PFGE and MLVA. The presence of the capsular antigen Vi was verified by PCR, and the phenotypic expression of the capsular antigen was determined serologically. Also, a plasmid analysis for each strain was carried out. The strains studied were divided into 35 different PFGE types and 89 MLVA‐types with a similarity of ≥80% and ≥17.5%, respectively. The plasmid sizes found ranged from 2 to >150 kb and none of the strains studied presented the capsular antigen Vi. Resistance or intermediate resistance was found in 23 strains (20.3%) that were resistant to ampicillin, ciprofloxacin, chloramphenicol, imipenem, nalidixic acid, piperacillin, streptomycin and/or tetracycline. The majority of the S. Dublin strains studied and isolated over a 33‐year period may descend from a common subtype that has been contaminating humans and animals in Brazil and able to cause invasive disease even in the absence of the capsular antigen. The higher diversity of resistance phenotypes in human isolates, as compared with animal strains, may be a reflection of the different anti‐microbial treatments used to control S. Dublin infections in humans in Brazil. 相似文献
995.
996.
I. Hajek F. Kettner V. Simerdova C. Rusbridge P. Wang B. A. Minassian V. Palus 《The Journal of small animal practice》2016,57(11):650-652
Lafora disease is a fatal genetic disorder characterised by neurotoxic deposits of malformed insoluble glycogen. In humans it is caused by mutation in the EPM2A or NHLRC1 genes. There is a known mutation in miniature wirehaired dachshunds which has not been documented in other dog breeds, including beagles, in which the disease is relatively commonly reported. This case report describes the causative defect in two affected beagles, namely the same massive expansion as in miniature wirehaired dachshunds of a 12‐nucleotide repeat sequence that is unique to the canine NHLRC1 gene. This is the first mutation described in beagles with Lafora disease, and so far the only Lafora disease genetic variant in dogs. 相似文献
997.
998.
Endothelin‐1 Immunoreactivity and its Association with Intramedullary Hemorrhage and Myelomalacia in Naturally Occurring Disk Extrusion in Dogs 下载免费PDF全文
999.
K. E. O'Neill M. A. Labato M. H. Court 《Journal of veterinary pharmacology and therapeutics》2016,39(2):202-204
Fenoldopam is a selective dopamine‐1 receptor agonist that improves diuresis by increasing renal blood flow and perfusion and causing peripheral vasodilation. Fenoldopam has been shown to induce diuresis and be well‐tolerated in healthy cats. It is used clinically in cats with oliguric kidney injury at doses extrapolated from human medicine and canine studies. The pharmacokinetics in healthy beagle dogs has been reported; however, pharmacokinetic data in cats are lacking. The goal of this study was to determine pharmacokinetic data for healthy, awake cats receiving an infusion of fenoldopam. Six healthy, awake, client‐owned cats aged 2–6 years old received a 120‐min constant rate infusion of fenoldopam at 0.8 μg/kg/min followed by a 20‐min washout period. Ascorbate stabilized plasma samples were collected during and after the infusion for the measurement of fenoldopam concentration by HPLC with mass spectrometry detection. This study showed that the geometric mean of the volume of distribution, clearance, and half‐life (198 mL/kg, 46 mL/kg/min, and 3.0 mins) is similar to pharmacokinetic parameters for humans. No adverse events were noted. Fenoldopam at a constant rate infusion of 0.8 μg/kg per min was well tolerated in healthy cats. Based on the results, further evaluation of fenoldopam in cats with kidney disease is recommended. 相似文献
1000.
Comparative plasma and milk dispositions,faecal excretion and efficacy of per os ivermectin and pour‐on eprinomectin in horses 下载免费PDF全文
C. Gokbulut M. Ozuicli D. Aksit E. Aksoz O. Korkut M. Yalcinkaya V. Y. Cirak 《Journal of veterinary pharmacology and therapeutics》2016,39(6):584-591
The horse milk gains increasing interest as a food product for sensitive consumers, such as children with food allergies or elderly people. We investigated the plasma and milk disposition, faecal excretion and efficacy of per os ivermectin (IVM) and pour‐on eprinomectin (EPM) in horses. Ten mares were divided into two groups. The equine paste formulation of IVM and bovine pour‐on formulation of EPM were administered orally and topically at dosage of 0.2 and 0.5 mg/kg bodyweight. Blood, milk and faecal samples were analysed using high‐performance liquid chromatography. The plasma concentration and persistence of IVM were significantly greater and longer compared with those of EPM. Surprisingly, EPM displayed a much higher disposition rate into milk (AUCmilk/plasma: 0.48) than IVM (AUCmilk/plasma: 0.19). IVM exhibited significantly higher faecal excretion (AUCfaeces: 7148.54 ng·d/g) but shorter faecal persistence (MRTfaeces: 1.17 days) compared with EPM (AUCfaeces: 42.43 ng·d/g and MRTfaeces: 3.29 days). Faecal strongyle egg counts (EPG) were performed before and at weekly intervals after treatment. IVM reduced the EPG by 96–100% for up to 8 weeks, whereas the reduction in the EPM group varied from 78 to 99%. In conclusion, due to the relatively low excretion in milk, EPM and IVM may be used safely in lactating mares if their milk is used for human consumption. Nevertheless, much lower plasma and faecal availabilities of EPM could result in subtherapeutic concentrations, which may increase the risk of drug resistance in nematodes after pour‐on EPM administration compared with per os IVM. 相似文献