全文获取类型
收费全文 | 6128篇 |
免费 | 278篇 |
国内免费 | 1篇 |
专业分类
林业 | 450篇 |
农学 | 139篇 |
基础科学 | 49篇 |
1037篇 | |
综合类 | 1146篇 |
农作物 | 351篇 |
水产渔业 | 383篇 |
畜牧兽医 | 2150篇 |
园艺 | 231篇 |
植物保护 | 471篇 |
出版年
2023年 | 34篇 |
2022年 | 42篇 |
2021年 | 118篇 |
2020年 | 118篇 |
2019年 | 127篇 |
2018年 | 112篇 |
2017年 | 94篇 |
2016年 | 121篇 |
2015年 | 109篇 |
2014年 | 143篇 |
2013年 | 266篇 |
2012年 | 327篇 |
2011年 | 391篇 |
2010年 | 210篇 |
2009年 | 176篇 |
2008年 | 403篇 |
2007年 | 395篇 |
2006年 | 397篇 |
2005年 | 403篇 |
2004年 | 414篇 |
2003年 | 401篇 |
2002年 | 362篇 |
2001年 | 78篇 |
2000年 | 60篇 |
1999年 | 67篇 |
1998年 | 49篇 |
1997年 | 39篇 |
1996年 | 68篇 |
1995年 | 53篇 |
1994年 | 48篇 |
1993年 | 50篇 |
1992年 | 52篇 |
1991年 | 32篇 |
1990年 | 49篇 |
1989年 | 42篇 |
1988年 | 33篇 |
1987年 | 34篇 |
1986年 | 29篇 |
1985年 | 42篇 |
1984年 | 43篇 |
1983年 | 39篇 |
1982年 | 24篇 |
1981年 | 21篇 |
1980年 | 20篇 |
1979年 | 17篇 |
1978年 | 22篇 |
1977年 | 29篇 |
1976年 | 20篇 |
1975年 | 22篇 |
1974年 | 25篇 |
排序方式: 共有6407条查询结果,搜索用时 31 毫秒
191.
Dystocia in the class Reptilia is a common problem. In turtles, it is often difficult to distinguish between a normal gravid state and dystocia. This case report describes nonobstructive dystocia in a free-living freshwater chelonian, Chelodina longicollis, complicated by traumatic injuries to the head, bridge, and plastron. Medical treatment of the dystocia and external fixation of the facial injuries provided a successful outcome. 相似文献
192.
The nutritional development of heifers from birth to the time they become pregnant with their second calf is a critical component of cowherd management. Veterinarians can use targeted body weights and condition scores to monitor progress and gauge future reproductive success throughout heifer development. Meeting Nutrient Requirements of Beef Cattle recommendations for net energy and metabolizable protein is the single most successful strategy for maximizing reproductive performance from birth through the second pregnancy. Supplementation with fat, minerals, and additional undegraded intake protein has not been consistently reported to enhance the reproductive function of heifers. 相似文献
193.
John M Sykes Michael M Garner Leah L Greer Nancy P Lung Rob L Coke Frank Ridgley Mitch Bush Richard J Montali Ben Okimoto Robert Schmidt Jack L Allen Bruce A Rideout Patricia A Pesavento Edward C Ramsay 《Journal of zoo and wildlife medicine》2007,38(2):300-308
Oral eosinophilic granulomas were diagnosed in 16 tigers (Panthera tigris). All lesions were located on the hard or soft palate and typically consisted of flat or slightly raised circular ulcers. Histologic features of these lesions were essentially identical to those seen in oral eosinophilic granulomas of domestic cats and dogs. No clinical signs were noted in eight cases, though various degrees of inappetence, excessive salivation, and dysphagia were noted in the other eight tigers. Six cases were not treated. Treatment for the remaining 10 cases centered on corticosteroids and additional treatments included surgical removal, cryotherapy, antibiotics, and chlorpheniramine. Treatment with corticosteroids did appear to be effective in some cases, though lesions would worsen after cessation of therapy and no cases were cured. In addition, three cases developed complications possibly related to this corticosteroid therapy. The etiology of these lesions remains unknown, though an underlying allergic condition is likely. 相似文献
194.
Prevalence of resistance to 11 antimicrobials among Campylobacter coill isolated from pigs on 80 grower-finisher farms in Ontario. 下载免费PDF全文
Norma P Varela Robert Friendship Cate Dewey 《Canadian journal of veterinary research》2007,71(3):189-194
We carried out a cross-sectional study to investigate antimicrobial resistance patterns of Campylobacter coli isolated from Ontario grower-finisher pigs. From January to June 2004, 1200 samples were collected from 80 farms by obtaining a constant number (15) of fecal samples per farm. Susceptibility of the isolates to 11 antimicrobial drugs was determined by the agar-dilution technique. The overall prevalence of resistance to 1 or more antimicrobials among the isolates was 99.2%. High levels of resistance were observed for azithromycin, clindamycin, erythromycin, streptomycin, and tetracycline: 91.7%, 82.5%, 81.4%, 70.7%, and 63.7%, respectively. For sulfamethoxazole, ampicillin, and nalidixic acid, resistance was observed in 40.3%, 26.6%, and 22.7% of the isolates, respectively. Although at very low levels, resistance was observed for ciprofloxacin (a fluoroquinolone), chloramphenicol, and gentamicin: in 2.4%, 1.7%, and 0.2%, respectively. Many of the isolates (29.7%) were resistant to 5 antimicrobials, the most common being azithromycin, clindamycin, erythromycin, streptomycin, and tetracycline. Isolates from the same farm showed at least 5 patterns of resistance. Results from this study indicate high levels of resistance to the antimicrobial drugs most commonly used in the Canadian swine industry (macrolides, lincosamides, and tetracyclines) among C. coli isolated from grower-finisher pigs in Ontario. Macrolides and fluoroquinolones are the drugs most commonly used to treat severe human campylobacteriosis. Fortunately, at present, there is little resistance to fluoroquinolones among C. coli from pigs in Ontario. 相似文献
195.
Robert N Streeter D L Step 《Veterinary Clinics of North America: Food Animal Practice》2007,23(3):541-74, vii
The use of diagnostic ultrasound equipment is becoming widespread within various sectors of veterinary practice. Ultrasonographic examination has several advantages over other imaging modalities and it can be applied in hospital and ambulatory settings. It has the potential for widespread use in the diagnosis of disorders of several body systems in food animal species. This article describes its application to gastrointestinal, hepatobiliary, cardiothoracic, urogenital, and umbilical disorders. Normal and abnormal findings are portrayed and discussed. Accurate and timely use of this diagnostic modality requires a modest amount of training and practice, but it allows for relatively rapid, inexpensive, and noninvasive acquisition of clinically relevant data. 相似文献
196.
Assessment of melamine and cyanuric acid toxicity in cats. 总被引:30,自引:0,他引:30
Birgit Puschner Robert H Poppenga Linda J Lowenstine Michael S Filigenzi Patricia A Pesavento 《Journal of veterinary diagnostic investigation》2007,19(6):616-624
The major pet food recall associated with acute renal failure in dogs and cats focused initially on melamine as the suspect toxicant. In the course of the investigation, cyanuric acid was identified in addition to melamine in the offending food. The purpose of this study was to characterize the toxicity potential of melamine, cyanuric acid, and a combination of melamine and cyanuric acid in cats. In this pilot study, melamine was added to the diet of 2 cats at 0.5% and 1%, respectively. Cyanuric acid was added to the diet of 1 cat at increasing doses of 0.2%, 0.5%, and 1% over the course of 10 days. Melamine and cyanuric acid were administered together at 0%, 0.2%, 0.5%, and 1% to 1 cat per dose group. No effect on renal function was observed in cats fed with melamine or cyanuric acid alone. Cats dosed with a combination were euthanized at 48 hours after dosing because of acute renal failure. Urine and touch impressions of kidneys from all cats dosed with the combination revealed the presence of fan-shaped, birefringent crystals. Histopathologic findings were limited to the kidneys and included crystals primarily within tubules of the distal nephron, severe renal interstitial edema, and hemorrhage at the corticomedullary junction. The kidneys contained estimated melamine concentrations of 496 to 734 mg/kg wet weight and estimated cyanuric acid concentrations of 487 to 690 mg/kg wet weight. The results demonstrate that the combination of melamine and cyanuric acid is responsible for acute renal failure in cats. 相似文献
197.
Gretchen D. Statz DVM Kari E. Moore DVM DACVECC Robert J. Murtaugh DVM MS DACVIM DACVECC 《Journal of Veterinary Emergency and Critical Care》2007,17(1):77-85
Objective: To describe the surgical repair and pre‐ and postoperative management of a peritoneopericardial diaphragmatic hernia (PPDH) in a pregnant dog. Case summary: A pregnant dog was presented for vomiting, lethargy, and pale mucous membranes. Pulsus paradoxus was noted on physical examination. The dog was diagnosed with a PPDH via thoracic radiographs, abdominal ultrasound, and an echocardiogram. The hernia was surgically repaired and the dog received supportive medical care until the puppies were old enough to be delivered via cesarean section. The mother and all puppies survived. New or unique information provided: This is the first report that describes the surgical repair and postoperative management of a PPDH in a pregnant dog. 相似文献
198.
199.
Dr.Robert Knox 《今日养猪业》2007,(4):3-6
一、诱导母猪发情与发情检测
发情是后备母猪受胎能力和筛选的标记,是经产母猪受胎能力的标记,以及输精时间的标记。[第一段] 相似文献
200.
Hlne Amory DVM PhD Dip. ECEIM Daniel Jean DMV MSc PhD Dip. ACVIM R. Leveille DVM Dip. ACVR Robert Higgins DVM MSc DSc Andr Vrins DVM 《Journal of Equine Veterinary Science》2006,26(8):364-369
Retropharyngeal infections in horses normally induce local painful swelling of the retropharyngeal area, which may lead to dyspnea, dysphagia, and systemic manifestations. Differential diagnosis of local painful swelling of the retropharyngeal area includes retropharyngeal lymph node infection, neoplasm, cellulitis, hematoma, guttural pouch empyema, parotiditis, and jugular thrombosis. Apart from Streptococcus equi ssp. equi, other bacteria are rarely reported as a cause of retropharyngeal abscesses. The reason for this might be a lack of specific sampling to identify the causative agent. This work deals with a case of retropharyngeal infection in an 11-year-old Standardbred stallion with acute depression, fever, tachycardia, asymmetric painful swelling in the throat area, ptyalism, and respiratory distress. Endoscopy, radiography, ultrasonography, blood analysis, and cytological examination of a puncture sample taken from the throat mass were consistent with a pyogenic to pyogranulomatous retropharyngeal inflammation. The clinical evolution was initially satisfactory in response to treatment with nonsteroidal anti-inflammatory drugs and antibiotics, but clinical signs relapsed twice, each time a few weeks after cessation of antibiotic therapy. The bacteriologic finding in this case was unusual and consisted of the isolation of a Pasteurella multocida strain that was obtained after the second relapse (ie, 79 days after initial admission), using a brain heart infusion (BHI) medium, and after two successive negative bacteriological cultures performed on day one of clinical signs and at the first relapse of clinical signs, respectively. 相似文献