全文获取类型
收费全文 | 84591篇 |
免费 | 4719篇 |
国内免费 | 65篇 |
专业分类
林业 | 2990篇 |
农学 | 2310篇 |
基础科学 | 572篇 |
9375篇 | |
综合类 | 15005篇 |
农作物 | 3116篇 |
水产渔业 | 3953篇 |
畜牧兽医 | 45990篇 |
园艺 | 898篇 |
植物保护 | 5166篇 |
出版年
2018年 | 1050篇 |
2017年 | 1178篇 |
2016年 | 1100篇 |
2015年 | 954篇 |
2014年 | 1190篇 |
2013年 | 3103篇 |
2012年 | 2173篇 |
2011年 | 2762篇 |
2010年 | 1681篇 |
2009年 | 1783篇 |
2008年 | 2660篇 |
2007年 | 2468篇 |
2006年 | 2464篇 |
2005年 | 2182篇 |
2004年 | 2139篇 |
2003年 | 2131篇 |
2002年 | 2008篇 |
2001年 | 2716篇 |
2000年 | 2814篇 |
1999年 | 2144篇 |
1998年 | 825篇 |
1997年 | 837篇 |
1996年 | 813篇 |
1995年 | 1025篇 |
1994年 | 900篇 |
1993年 | 855篇 |
1992年 | 1936篇 |
1991年 | 2086篇 |
1990年 | 1929篇 |
1989年 | 1941篇 |
1988年 | 1830篇 |
1987年 | 1932篇 |
1986年 | 1983篇 |
1985年 | 1882篇 |
1984年 | 1488篇 |
1983年 | 1308篇 |
1982年 | 884篇 |
1979年 | 1373篇 |
1978年 | 1131篇 |
1977年 | 982篇 |
1976年 | 941篇 |
1975年 | 986篇 |
1974年 | 1273篇 |
1973年 | 1299篇 |
1972年 | 1234篇 |
1971年 | 1147篇 |
1970年 | 1088篇 |
1969年 | 965篇 |
1968年 | 833篇 |
1967年 | 869篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Disseminated histoplasmosis and disseminated intravascular coagulopathy were diagnosed in a 7 mo old, female spayed mixed-breed dog. The dog improved transiently with supportive care, but deteriorated shortly after initiation of antifungal therapy. The dog was subsequently euthanized. At necropsy, marked granulomatous vasculitis was identified in all affected organs. The tunicae and laminae of the arteries and arterioles were obscured by epithelioid macrophages and multinucleated giant cells admixed with necrotic material. Intracytoplasmic yeast were present within some of these macrophages. To the authors' knowledge, this is the first reported case of granulomatous vasculitis associated with Histoplasma capsulatum in a dog. 相似文献
952.
The aim of this investigation was to determine the efficacy of milbemycin oxime in preventing the oesophageal encapsulation of Spirocerca lupi, following the experimental infection of dogs. Two studies were conducted which involved a total of 21 purpose-bred Beagles. Each dog was infected with approximately 40, third stage infective S. lupi larvae. The larvae were dissected from scarabaeid beetles that had been collected from areas endemic for spirocercosis. In the first study, milbemycin oxime (minimum dose 0.5mg/kg body weight) was administered to seven dogs on day 30 post-infection. Seven other dogs served as untreated controls. In the second study, milbemycin oxime (also at a minimum dose of 0.5mg/kg body weight) was administered to four of seven infected dogs on day 28 post-infection. Treatment was repeated at 14- or 28-day intervals. All of the dogs, from both studies, were euthanized 168 or 169 days after infection. All S. lupi were recovered, and lesions in the thoracic aorta and oesophagus were described and quantified. A single treatment with milbemycin oxime was 79.8% effective in preventing the establishment of S. lupi in the oesophagus. This treatment significantly (p<0.05) reduced both the number of S. lupi within the oesophagus and the size of the oesophageal nodules. The efficacy of anthelmintic treatment was increased to 100% when repeat doses of milbemycin oxime were administered at 14- or 28-day intervals. These repeat treatments completely prevented the establishment of S. lupi within the oesophagus and thereby averted the development of oesophageal nodules. As expected, none of the treatment protocols reduced S. lupi related damage within the aorta because the administration of milbemycin oxime only began after the larvae had completed their first stage of migration. 相似文献
953.
954.
Deeming DC 《British poultry science》2011,52(1):40-47
1. The possible role of the presence of the yolk in stimulating secretion of albumen was investigated. 2. Double-yolked and single-yolked pheasant (Phasianus colchinus) eggs were opened to determine the masses of the shell, albumen and yolk(s). 3. In double-yolked eggs, the two yolk masses were not significantly different. Albumen mass was increased above that expected from an egg with a single-yolk of comparable size but below that expected from an egg having a mass of the combined yolks. The mass of shell per unit area reflected the mass of the initial mass of the egg irrespective of the number of yolks. 4. The additional mass of albumen is unrelated to yolk or initial egg mass. It is postulated that in double-yolked eggs the oviduct is mechanically stimulated by the presence of both yolks, which empties the stores of water-soluble albumen proteins in the magnum wall. Such stores are insufficient to provide the same amount of protein for the two yolks. 相似文献
955.
Holtkamp DJ Polson DD Torremorell M Morrison B Classen DM Becton L Henry S Rodibaugh MT Rowland RR Snelson H Straw B Yeske P Zimmerman J;American Association of Swine Veterinarians;United States Department of Agriculture PRRS-Coordinated Agricultural Project 《Tier?rztliche Praxis. Ausgabe G, Grosstiere/Nutztiere》2011,39(2):101-112
Standardized terminology for the porcine reproductive and respiratory syndrome virus (PRRSV) status of swine herds is necessary to facilitate communication between veterinarians, swine producers, genetic companies, and other industry participants. It is also required for implementation of regional and national efforts towards PRRSV control and elimination. The purpose of this paper is to provide a herd classification system for describing the PRRSV status of herds, based upon a set of definitions reflecting the biology and ecology of PRRSV. The herd classification system was developed by a definitions committee formed jointly by the American Association of Swine Veterinarians (AASV) and the United States Department of Agriculture PRRS-Coordinated Agricultural Project, and was approved by the AASV Board of Directors on March 9, 2010. The committee included veterinarians from private practice and industry, researchers, and representatives from AASV and the National Pork Board. Breeding herds, with or without growing pigs on the same premises, are categorized as Positive Unstable (Category I), Positive Stable (Category II), Provisional Negative (Category III), or Negative (Category IV) on the basis of herd shedding and exposure status. Growing-pig herds are categorized as Positive or Negative. Recommended testing procedures and decision rules for herd classification are detailed. 相似文献
956.
957.
958.
Eberts MD Vissotto de Paiva Diniz PP Beall MJ Stillman BA Chandrashekar R Breitschwerdt EB 《Journal of the American Animal Hospital Association》2011,47(6):e86-e94
Eighteen clinically ill dogs, naturally infected with Anaplasma phagocytophilum, were examined at a veterinary practice in Baxter, Minnesota. A clinical examination, complete blood cell count, enzyme- linked immunosorbent assay (ELISA) for A phagocytophilum, Borrelia burgdorferi, and Ehrlichia canis antibodies and Dirofilaria immitis antigen, and a polymerase chain reaction test for A phagocytophilum DNA were obtained for all dogs. Physical examination findings included fever, arthropathy, lymphadenopathy, epistaxis, acute gastritis, cervical hyperpathia, and central nervous system dysfunction. Complete blood cell count abnormalities included thrombocytopenia, morulae in neutrophils, anemia, leukopenia, eosinopenia, lymphopenia, and monocytosis. Seroreactivity to A phagocytophilum was found in 61%, B burgdorferi antibodies in 17%, and D immitis antigen in 5% of the dogs. Fever, arthropathy, neurologic dysfunction, and epistaxis are clinical syndromes that can be associated with A phagocytophilum infection. Treatment with doxycycline resulted in rapid resolution of clinical signs in all dogs. 相似文献
959.
960.
F. L. Pollari B. N. Bonnett D. G. Allen S. C. Bamsey S. W. Martin 《Preventive veterinary medicine》1996,27(3-4):141-154
This study was designed to evaluate the quality of data from computerized medical record abstracts at the Veterinary Teaching Hospital, Ontario Veterinary College. Information in the paper medical record (registration, physical exam, daily progress, laboratory, radiology, anaesthesia and surgery forms), the summary sheet, and the computerized record were compared. A random sample of 100 patient visits from a subset of visits that were identified as all possible dog or cat elective-surgery visits in the computerized records from 1983 through 1991 were used. Clinicians were responsible for summarizing the medical record on the summary sheet and health record technicians entered the information from the summary sheet into the computer record. Most of the discrepancies (n = 33) noted for diagnoses, procedures or complications were due to the lack of transfer of information from the paper forms to the summary sheet. Although the medical record technicians detected and entered some of these (n = 10), most were not entered into the computerized records. The next most-common discrepancies (n = 5) were due to the clinician writing a different entry on the summary sheet than was present on the other paper record forms. Only one record had a miscoded diagnosis and three had miscoded procedures. Misfiled forms in the medical record folders of two patients resulted in one incorrect diagnosis and one incorrect procedure recorded in the computer record. When any discrepancy between the paper and computer record for diagnoses, procedures or complications was considered, 41% of the visits had discrepancies (46% dogs; 36% cats). The percentage varied by surgery status: non-elective surgeries 82%, elective surgeries 37% and non-surgical visits 29%. There was no obvious time trend. The completeness and accuracy of information in the database was inadequate for the intended research on post-operative complications following elective surgeries. 相似文献