全文获取类型
收费全文 | 121992篇 |
免费 | 6892篇 |
国内免费 | 66篇 |
专业分类
林业 | 5240篇 |
农学 | 3885篇 |
基础科学 | 720篇 |
14131篇 | |
综合类 | 20427篇 |
农作物 | 4500篇 |
水产渔业 | 5820篇 |
畜牧兽医 | 64765篇 |
园艺 | 1463篇 |
植物保护 | 7999篇 |
出版年
2018年 | 1665篇 |
2017年 | 1786篇 |
2016年 | 1639篇 |
2015年 | 1466篇 |
2014年 | 1712篇 |
2013年 | 4839篇 |
2012年 | 3249篇 |
2011年 | 3870篇 |
2010年 | 2575篇 |
2009年 | 2577篇 |
2008年 | 3794篇 |
2007年 | 3699篇 |
2006年 | 3428篇 |
2005年 | 3208篇 |
2004年 | 3030篇 |
2003年 | 3243篇 |
2002年 | 2995篇 |
2001年 | 3625篇 |
2000年 | 3556篇 |
1999年 | 2899篇 |
1998年 | 1231篇 |
1997年 | 1264篇 |
1995年 | 1382篇 |
1994年 | 1211篇 |
1993年 | 1200篇 |
1992年 | 2450篇 |
1991年 | 2710篇 |
1990年 | 2568篇 |
1989年 | 2633篇 |
1988年 | 2428篇 |
1987年 | 2363篇 |
1986年 | 2521篇 |
1985年 | 2417篇 |
1984年 | 2028篇 |
1983年 | 1803篇 |
1982年 | 1232篇 |
1979年 | 1881篇 |
1978年 | 1460篇 |
1977年 | 1398篇 |
1976年 | 1360篇 |
1975年 | 1405篇 |
1974年 | 1732篇 |
1973年 | 1760篇 |
1972年 | 1689篇 |
1971年 | 1555篇 |
1970年 | 1561篇 |
1969年 | 1520篇 |
1968年 | 1308篇 |
1967年 | 1391篇 |
1966年 | 1143篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
191.
Design and performance information on a filtered-air positive-pressure (FAPP) housing system for disease-free poultry flocks is presented. The system includes many special features that result in excellent biological security, easy cleanup and maintenance, efficient control of environment, and a centralized alarm in the event of problems. The system has now housed eight flocks without any major problems. Based on its performance thus far, it should be useful as a reliable housing system for disease-free poultry. 相似文献
192.
Intraperitoneal Circulation and Drainage in the Dog 总被引:1,自引:0,他引:1
GISELLE HOSGOOD BVSc MS FACVSc S. KATHLEEN SALISBURY DVM MS DiplomateACVS H. DAN CANTWELL DVM MS DiplomateACVR DENNIS B. DENICOLA DVM PhD DiplomateACVP 《Veterinary surgery : VS》1989,18(4):261-268
The patterns of dispersion and drainage of a low viscosity, oil-based contrast medium within the peritoneal cavity were examined in 12 normal dogs. Intraperitoneal injection of contrast medium was cranial or caudal and drainage was by the sump-Penrose or open peritoneal method. Radiographs were made over a 96 hour period, before and after peritoneal drainage was established. Each dog was euthanatized and necropsied. The contrast medium was dispersed throughout the peritoneal cavity 15 to 30 minutes after cranial injection and 1 to 2 hours after caudal injection. Most of the contrast medium drained within 6 hours after open peritoneal drainage and within 24 to 48 hours after sump-Penrose drainage. At necropsy, there was complete encasement of all sump-Penrose drains and partial occlusion of all open peritoneal incisions by omentum adhered to the abdominal wound edges. Peritonitis was not grossly evident, but all dogs showed histologic evidence of an acute inflammatory reaction associated with the drain or wound edge. 相似文献
193.
2 groups of 20 cocks each were selected at random from non-dwarf White Leghorn (28 weeks post-hatch) and dwarf Krishna-J (38 weeks post-hatch) genotypes. The treated groups comprised 10 White Leghorn and 10 Krishna-J cocks. The remaining birds served as controls. 8 weeks prior to furazolidone treatment, semen was collected from both control groups at regular 4-day intervals, for 4 weeks. Cocks of the treated groups of both genotypes were administered furazolidone (0.14 g/bird/day) for 7 consecutive days. Semen was collected from all cocks at regular 4-day intervals for 4 weeks. Semen from the cocks of the same group was pooled. The pooled ejaculate volume and sperm density did not differ significantly in the 2 genotypes. The semen output as well as sperm density increased along with progressive attainment of sexual maturity. Furazolidone treatment caused significant reduction in semen volume as well as sperm concentration in either genotype. 相似文献
194.
Gastro-oesophageal reflux together with sliding hiatus hernia is reported in a dog, associated with laryngeal paralysis. Diagnosis was made following endoscopy and fluoroscopy. Surgical treatment of the laryngeal paralysis resulted in complete remission of clinical signs. 相似文献
195.
196.
The management of guttural pouch mycosis 总被引:1,自引:0,他引:1
J G Lane 《Equine veterinary journal》1989,21(5):321-324
197.
198.
199.
The structure of the shell of the egg of Trichuris trichiura was examined using light microscopy as well as scanning and transmission electron microscopy. The results confirmed its three-layered structure and provided evidence that the cores of the polar plugs, which could be seen to be extensions of the shell's middle layer, could be lost en bloc, either mechanically or chemically, and in this way probably provided an exit for the first stage larva at hatching. 相似文献
200.
M A Albassam B J Houston P Greaves N Barsoum 《Journal of the American Veterinary Medical Association》1989,194(11):1595-1597
A 13-month-old Beagle became anorectic and had fever, stiff gait, and tenderness in the inguinal region. Clinical signs of disease were associated with neutrophilia and a decrease in the albumin-to-globulin ratio. The dog became clinically normal for 5 days after 3 days of treatment with penicillin G and dihydrostreptomycin. Clinical signs of disease recurred, and the dog was euthanatized after failing to respond to administration of a trimethoprim-sulfamethoxazole combination for 9 days. Disseminated arteritis was seen in the testes, epididymides, mesentery, coronary arteries, aorta, and thyroid gland. Lesions were seen in large and medium-sized arteries and varied from acute necrotizing arteries to a chronic lesion with organization and recanalization of thrombi. The clinical signs of disease resembled those of Beagle pain syndrome, described in laboratory Beagles. 相似文献