全文获取类型
收费全文 | 1176篇 |
免费 | 51篇 |
国内免费 | 1篇 |
专业分类
林业 | 69篇 |
农学 | 37篇 |
基础科学 | 10篇 |
180篇 | |
综合类 | 164篇 |
农作物 | 96篇 |
水产渔业 | 115篇 |
畜牧兽医 | 471篇 |
园艺 | 28篇 |
植物保护 | 58篇 |
出版年
2023年 | 9篇 |
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 19篇 |
2019年 | 25篇 |
2018年 | 25篇 |
2017年 | 25篇 |
2016年 | 22篇 |
2015年 | 17篇 |
2014年 | 30篇 |
2013年 | 47篇 |
2012年 | 43篇 |
2011年 | 82篇 |
2010年 | 53篇 |
2009年 | 50篇 |
2008年 | 82篇 |
2007年 | 72篇 |
2006年 | 80篇 |
2005年 | 67篇 |
2004年 | 65篇 |
2003年 | 61篇 |
2002年 | 55篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 17篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 16篇 |
1992年 | 9篇 |
1991年 | 17篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 13篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1966年 | 4篇 |
排序方式: 共有1228条查询结果,搜索用时 0 毫秒
21.
Cazabon EP Adogwa AO 《The Canadian veterinary journal. La revue veterinaire canadienne》2003,44(1):56-58
A case of cephalothoracopagus in sheep complicated with several defects of skeletal, cardiovascular, respiratory, gastrointestinal, and urogenital systems is reported. 相似文献
22.
OBJECTIVE: To determine the effect of histamine on the contractile elements of the respiratory tract in neonatal calves and young adult cattle. SAMPLE POPULATION: Samples of trachealis muscle, bronchi, and intrapulmonary arteries and veins dissected from the respiratory tracts of healthy bovids (2 to 8 days and 16 to 20 months old). PROCEDURE: Histamine cumulative concentration-effect curves (10(-6) to 10(-3) M) were constructed in duplicate smooth muscle samples mounted in organ baths. Contractile responses to histamine were compared with reference contractions elicited by methacholine (10(-5) M) for airways or KCl (127 mM) for vessels. RESULTS: In young adult cattle, trachealis muscle had a substantial contractile response to histamine (84% of methacholine-induced contraction), whereas bronchi reacted slightly (15 and 20% for large and small bronchi, respectively). Although contractile responses to KCl were comparable in arteries and veins, histamine-induced contractions were greater for intrapulmonary veins than for arteries (202 vs 48% of KCl-induced contraction). In neonatal calves, histamine-induced contraction of veins also exceeded that of arteries (230 vs 54% of KCl-induced contraction); however, unlike in young adult cattle, histamine produced notable contraction of large and small bronchi (48 and 60% of methacholine-induced contraction, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Compared with intrapulmonary arteries, intrapulmonary veins have greater contractile responses to histamine in neonatal and young adult cattle. Data suggest loss of histamine responsiveness in bronchial smooth muscle as neonatal calves grow to young adults. Venodilation may be useful in treatment of lung edema in cattle. 相似文献
23.
Pressler BM Hardie EM Pitulle C Hopwood RM Sontakke S Breitschwerdt EB 《Journal of the American Veterinary Medical Association》2002,220(9):1336-40, 1313-4
A 3-year-old spayed female Whippet was examined for cough and respiratory distress. Lung lobe torsion with pleural effusion was diagnosed, and lung lobectomy was performed. Pleural effusion recurred during the following 27 months; conventional bacteriologic cultures of pleural effusion did not result in bacterial growth. A second lung lobectomy, pleuroperitoneal shunt placement. and pericardectomy were subsequently performed. Mycobacterium kansasii was eventually isolated from pleural fluid and identified by polymerase chain reaction amplification and DNA sequencing. The dog was euthanatized before therapeutic response could be evaluated. To our knowledge, this is the first report of M. kansasii infection in a dog. Additionally, this is the first report of mycobacterial isolation from pleural fluid, and one of few reports of antemortem mycobacterial isolation from a body fluid, as opposed to identification in specimens during histologic examination. Routine bacteriologic culture methods are insufficient to isolate mycobacterial agents, and special methods are indicated in dogs with persistent pleural effusion. 相似文献
24.
Holcombe SJ Cornelisse CJ Berney C Robinson NE 《American journal of veterinary research》2002,63(12):1617-1621
OBJECTIVE: To determine whether the hyoepiglotticus muscle has respiratory-related electromyographic activity and whether electrical stimulation of this muscle changes the position and conformation of the epiglottis, thereby altering dimensions of the aditus laryngis. ANIMAL: 6 Standardbred horses. PROCEDURE: Horses were anesthetized, and a bipolar fine-wire electrode was placed in the hyoepiglotticus muscle of each horse. Endoscopic images of the nasopharynx and larynx were recorded during electrical stimulation of the hyoepiglotticus muscle in standing, unsedated horses. Dorsoventral length and area of the aditus laryngis were measured on images obtained before and during electrical stimulation. Electromyographic activity of the hyoepiglotticus muscle and nasopharyngeal pressures were measured while horses exercised on a treadmill at 50, 75, 90, and 100% of the speed that produced maximum heart rate. RESULTS: Electrical stimulation of the hyoepiglotticus muscle changed the shape of the epiglottis, displaced it ventrally, and significantly increased the dorsoventral length and area of the aditus laryngis. The hyoepiglotticus muscle had inspiratory activity that increased significantly with treadmill speed as a result of an increase in phasic and tonic activity. Expiratory activity of the hyoepiglotticus muscle did not change with treadmill speed in 4 of 6 horses. CONCLUSIONS AND CLINICAL RELEVANCE: Findings reported here suggest that contraction of the hyoepiglotticus muscle increases dimensions of the airway in horses by depressing the epiglottis ventrally during intense breathing efforts. The hyoepiglotticus muscle may be an important muscle for dilating the airway in horses, and contraction of the hyoepiglotticus muscle may induce conformational changes in the epiglottis. 相似文献
25.
Lugo J Stick JA Peroni J Harkema JR Derksen FJ Robinson NE 《American journal of veterinary research》2002,63(9):1232-1240
OBJECTIVE: To evaluate the safety and efficacy of thoracoscopically guided pulmonary wedge resection in horses. ANIMALS: 10 horses (5 control horses and 5 horses affected with recurrent airway obstruction [ie, heaves]). PROCEDURE: Each horse underwent a thoracoscopically guided pulmonary wedge resection. Before, during, and after surgery, heart rate, respiratory rate, arterial blood gases, and systemic and pulmonary arterial pressures were measured. Physical examination, CBC, and thoracic radiography and ultrasonography were performed 24 hours before and 2 and 48 hours after surgery. Pulmonary specimens were assessed by histologic examination. A second thoracoscopic procedure 14 days later was used to evaluate the resection site. RESULTS: The technique provided excellent specimens for histologic evaluation of the lung. Heart and respiratory rates decreased significantly after horses were administered sedatives. A significant transient decrease in Pao2 was detected immediately after pulmonary wedge resection, but we did not detect significant effects on arterial pH, Paco2, or mean arterial and pulmonary arterial pressures. All horses except 1 were clinically normal after thoracoscopic surgery; that horse developed hemothorax attributable to iatrogenic injury to the diaphragm. The second thoracoscopy revealed minimal inflammation, and there were no adhesions. CONCLUSIONS AND CLINICAL RELEVANCE: Thoracoscopically guided pulmonary wedge resection provides a minimally invasive method for use in obtaining specimens of lung tissues from healthy horses and those with lung disease. This technique may be useful for the diagnosis of diseases of the lungs and thoracic cavity. 相似文献
26.
27.
Roth JA Hibbard B Frank DE Kesl L Robb EJ 《Veterinary therapeutics : research in applied veterinary medicine》2002,3(3):347-353
Holstein steer calves received a single injection of Miglyol (Sasol Chemical Industries, Ltd.) subcutaneously as a placebo, dihydroheptaprenol (DHP) (4 mg/kg) emulsified with lecithin subcutaneously, DHP in solution in Miglyol (4 mg/kg) subcutaneously, or DHP in solution in Miglyol (4 mg/kg) intranasally. The DHP emulsified in lecithin emulsion administered subcutaneously caused a substantial increase in body temperature, total leukocyte count, total neutrophil count, neutrophil cytochrome-c reduction, and neutrophil iodination 24 hours after administration and, for some of the parameters, at 48 hours. The DHP formulation in Miglyol did not have any of these effects when administered subcutaneously or intranasally. The carrier and formulation of DHP apparently have major effects on the biologic activity of DHP. 相似文献
28.
Neer TM Breitschwerdt EB Greene RT Lappin MR 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2002,16(3):309-315
Within the past several decades, the number of Ehrlichia spp. recognized to infect cats, dogs, and human beings has expanded substantially. The recent application of advanced techniques in molecular biology has changed how ehrlichiosis is diagnosed and has provided new tools for the assessment of treatment. As these techniques are applied, the numerous questions that relate to the management of dogs and cats with ehrlichiosis ultimately will be answered. We hope this consensus statement will assist veterinarians in the management of their patients. 相似文献
29.
Julia H Wilson Erik J Olson Edward W Haugen Luanne M Hunt Jennifer L Johnson David W Hayden 《Journal of veterinary diagnostic investigation》2006,18(6):615-619
Progressive multisystemic disease caused by Blastomyces dermatitidis was diagnosed in a 17-year-old Quarter horse broodmare. The mare had been treated unsuccessfully with antibiotics for mastitis 3 months postpartum. The disease progressed to exudative cutaneous lesions affecting the ventrum, pectoral region, and limbs accompanied by weight loss across several months. Yeast bodies were observed in swabs of the cutaneous exudate, suggesting a clinical diagnosis of blastomycosis. Following referral, pleural effusion, cavitated lung lesions, and hyperproteinemia were identified, and the mare was euthanized because of poor prognosis. Necropsy revealed extensive pyogranulomas in the mammary gland, skin, subcutaneous tissues, and lungs, accompanied by thrombi in major blood vessels of the lungs and hind limbs. Histologically, pyogranulomatous inflammation was evident in many tissues, and fungal organisms were seen in sections of mammary gland, skin, subcutis, pericardium, and lung. Blastomyces dermatitidis was cultured from mammary tissue, lungs, lymph node, and an inguinal abscess. Although blastomycosis is endemic in the area of origin of the mare in northwestern Wisconsin, the disease is extremely rare in horses and hence easily misdiagnosed. Unique features of this case included the extent of mammary gland involvement and the presence of thrombi in multiple sites. 相似文献
30.
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