全文获取类型
收费全文 | 78304篇 |
免费 | 4433篇 |
国内免费 | 36篇 |
专业分类
林业 | 4081篇 |
农学 | 2556篇 |
基础科学 | 481篇 |
9786篇 | |
综合类 | 12430篇 |
农作物 | 2969篇 |
水产渔业 | 3716篇 |
畜牧兽医 | 40487篇 |
园艺 | 960篇 |
植物保护 | 5307篇 |
出版年
2018年 | 1124篇 |
2017年 | 1225篇 |
2016年 | 1139篇 |
2015年 | 972篇 |
2014年 | 1201篇 |
2013年 | 3078篇 |
2012年 | 2216篇 |
2011年 | 2585篇 |
2010年 | 1683篇 |
2009年 | 1708篇 |
2008年 | 2561篇 |
2007年 | 2479篇 |
2006年 | 2295篇 |
2005年 | 2205篇 |
2004年 | 2061篇 |
2003年 | 2226篇 |
2002年 | 1990篇 |
2001年 | 2397篇 |
2000年 | 2329篇 |
1999年 | 1842篇 |
1998年 | 749篇 |
1997年 | 806篇 |
1996年 | 725篇 |
1995年 | 937篇 |
1994年 | 775篇 |
1993年 | 759篇 |
1992年 | 1522篇 |
1991年 | 1660篇 |
1990年 | 1626篇 |
1989年 | 1628篇 |
1988年 | 1516篇 |
1987年 | 1469篇 |
1986年 | 1559篇 |
1985年 | 1481篇 |
1984年 | 1292篇 |
1983年 | 1080篇 |
1982年 | 762篇 |
1979年 | 1186篇 |
1978年 | 901篇 |
1977年 | 859篇 |
1976年 | 816篇 |
1975年 | 844篇 |
1974年 | 1040篇 |
1973年 | 1083篇 |
1972年 | 1032篇 |
1971年 | 962篇 |
1970年 | 938篇 |
1969年 | 907篇 |
1968年 | 766篇 |
1967年 | 857篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
G. Sahoo T. More V.K. Singh 《Comparative immunology, microbiology and infectious diseases》1998,21(4):319-325
In the present study the level of enzyme hydrolases (alkaline phosphatase, myeloperoxidase, elastase, arginase, lysozyme and β-galactosidase) of polymorphonuclear cell (PMN) granules in different ruminant species and their release in response to activation was studied. Buffalo PMN alkaline phosphatase activity was higher (P < 0.01) than in PMNs of cattle and goats. Interestingly, myeloperoxidase was higher in cattle PMNs and least in goat PMNs (P < 0.01), a similar pattern was observed in the distribution of enzyme arginase. As far as lysozyme is concerned, its activity was significantly higher (P < 0.01) in PMNs of buffaloes than in the case of cattle and goat PMNs. On activation, these cells released MPO and elastase, in all the species studied, while lysozyme was secreted only in buffalo PMN cells. Activity of certain enzymes related to oxidant defence systems such as glutathione peroxidase and glutathione reductase were higher in cattle and goats compared to that in buffaloes. These observations are likely to have bearing on immunodefense roles played by PMNs and reflected differences among the ruminant species studied. 相似文献
192.
193.
194.
A RETROSPECTIVE STUDY OF OSTEOMYELITIS IN DOGS AND CATS 总被引:1,自引:0,他引:1
Thirty-nine cases of osteomyelitis in dogs and cats were recorded at the Sydney University Veterinary Hospital and Clinic over a three and a half year period. In 36 cases osteomyelitis was established prior to admission. Three cases of osteomyelitis became established from a total of 502 orthopaedic surgery cases seen at the hospital in this period. In the dog the most common source of infection was open reduction of closed fractures, while in the cat, the most common source of infection was an extension from soft tissue infection. More males than females were affected. Ten cases of osteomyelitis were treated successfully, twelve cases required amputation, while euthanasia was performed on thirteen other cases. The problems and principles of treatment of active osteomyelitis as reflected in the treatment of this series of cases have been described. 相似文献
195.
196.
A.L. Soraci D.S. Perez G. Martinez S. Dieguez M.O. Tapia F. Amanto R. Harkes O. Romano 《Research in veterinary science》2011,90(3):498-502
Disodium-fosfomycin pharmacokinetics has been studied in different species after oral, intravenous, intramuscular and subcutaneous administration. At present there are neither documented clinical experiences of the use of fosfomycin in pigs nor any published studies in weaning piglets, although it is a period of high incidence of infectious diseases. The pharmacokinetics and the bioavailability of sodium fosfomycin were studied in post weaning piglets after intravenous and intramuscular administration of 15 mg/kg of body weight. Plasma concentrations were measured by a high-performance liquid ms/ms. After IV administration the area under the fosfomycin concentration:time curve in plasma was AUC(0–12) of 120.00 ± 23.12 μg h/ml and the volume of distribution (Vd) of 273.00 ± 40.70 ml/kg. The elimination was rapid with a plasma clearance of 131.50 ± 30.07 ml/kg/h and a T1/2 of 1.54 ± 0.40 h. Peak serum concentration (Cmax), Tmax, AUC(0–12) and bioavailability for the IM administration were 43.00 ± 4.10 μg/ml, 0.75 ± 0.00 h, 99.00 ± 0.70 μg h/ml and 85.5 ± 9.90% respectively. Different authors have determined a minimum inhibitory concentration (MIC90) ranging from 0.25 μg/ml for Streptococcus sp. and 0.5 μg/ml for Escherichia coli. Considering the above, and according to the values of plasma concentration vs time profiles observed in this study, effective plasma concentrations of fosfomycin for sensitive bacteria can be obtained following IV and IM administration of 15 mg/kg in piglets. 相似文献
197.
A gray-cheeked parakeet, approximately 3 years of age, was submitted for necropsy. Clinical signs included diarrhea, decreased feed consumption, fluffing of feathers, shivering, weight loss, and limping. Necropsy revealed enlargement and pale discoloration of the spleen and intestines. The liver contained multifocal pale foci. Granulomas, some of which had necrotic centers, were present along the subserosa of the intestinal tract. Microscopic examination revealed diffuse granulomatous splenitis, enteritis, and multifocal granulomatous hepatitis. Numerous acid-fast bacteria were demonstrated in the spleen, liver, and intestine. 相似文献
198.
OBJECTIVE: To evaluate the use of arthroscopy as the primary method for removal of large patellar fracture fragments. DESIGN: Retrospective study. ANIMALS: 5 performance horses of various breeds with patellar fractures. PROCEDURE: Clinical signs of lameness, external evidence of injury, and radiography were used to diagnose and determine fracture orientation. Arthroscopy of the stifle joint was performed on the affected limb with the horse positioned in dorsal recumbency and under general anesthesia. Progress after surgery was determined by evaluating medical records and via telephone conversations with owners. RESULTS: 4 of 5 horses had fractures of the medial aspect of the patella and 1 horse had a fracture of the lateral aspect of the patella. There were no postoperative complications with the joint or the arthroscopic portal incisions. Recovery periods ranged from 3 to 5 months. All horses recovered completely from surgery, and performed at the same or higher level of competition as before arthroscopy. CONCLUSIONS AND CLINICAL RELEVANCE: Femoropatellar joint arthroscopy is a favorable means by which evaluation of the stifle joint and removal of large fracture fragments can be achieved with negligible postoperative complications. 相似文献
199.
Müller U Kappeler A Zanoni RG Breitenmoser U 《Schweizer Archiv für Tierheilkunde》2000,142(8):431-438
The rabies epidemic that reached Switzerland in 1967 developed in response to landscape factors as long as no efficient control strategies were available. The landscape acted either as barrier to the spread of rabies, or it influenced the density of red foxes and thus the habitat of the epidemic. Following the first cases in the canton of Schaffhausen, the whole northwestern Switzerland was infected followed by the eastern Alps, large parts of the Plateau and the Jura mountains. In 1978, in the canton of Valais, the first campaigns of oral immunization of foxes against rabies started. The design of vaccination campaigns during the next two decades was always closely linked to landscape features. Thus, it was possible to free first the Alps and then the Plateau from rabies and finally, at the end of the 1990s, to eliminate it completely within the country. We describe the entire development of the epidemic within the period of 30 years from the first infection up to the last registered case and the final vaccination campaign. 相似文献