全文获取类型
收费全文 | 173221篇 |
免费 | 9432篇 |
国内免费 | 120篇 |
专业分类
林业 | 7177篇 |
农学 | 5543篇 |
基础科学 | 1051篇 |
21557篇 | |
综合类 | 29004篇 |
农作物 | 6733篇 |
水产渔业 | 8582篇 |
畜牧兽医 | 89376篇 |
园艺 | 2330篇 |
植物保护 | 11420篇 |
出版年
2019年 | 1665篇 |
2018年 | 2554篇 |
2017年 | 2851篇 |
2016年 | 2575篇 |
2015年 | 2207篇 |
2014年 | 2710篇 |
2013年 | 7020篇 |
2012年 | 5096篇 |
2011年 | 6268篇 |
2010年 | 4073篇 |
2009年 | 4147篇 |
2008年 | 6093篇 |
2007年 | 5767篇 |
2006年 | 5440篇 |
2005年 | 5062篇 |
2004年 | 4797篇 |
2003年 | 4948篇 |
2002年 | 4509篇 |
2001年 | 5277篇 |
2000年 | 5313篇 |
1999年 | 4257篇 |
1998年 | 1890篇 |
1997年 | 1791篇 |
1996年 | 1662篇 |
1995年 | 1968篇 |
1994年 | 1777篇 |
1993年 | 1631篇 |
1992年 | 3421篇 |
1991年 | 3612篇 |
1990年 | 3457篇 |
1989年 | 3449篇 |
1988年 | 3153篇 |
1987年 | 3146篇 |
1986年 | 3244篇 |
1985年 | 3187篇 |
1984年 | 2584篇 |
1983年 | 2319篇 |
1982年 | 1569篇 |
1979年 | 2405篇 |
1978年 | 1943篇 |
1977年 | 1682篇 |
1976年 | 1732篇 |
1975年 | 1809篇 |
1974年 | 2145篇 |
1973年 | 2123篇 |
1972年 | 1998篇 |
1971年 | 1850篇 |
1970年 | 1825篇 |
1969年 | 1831篇 |
1967年 | 1627篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
121.
122.
123.
Colitis cystica profunda in dogs has been diagnosed in one case only. The two own cases were characterized by repeated, partly bloody diarrhea, vomitus, and painful defecation. The disease was diagnosed by clinical examination and colonoscopy with the ensuing histological examination of biopsy specimens. The disease could be managed by administration of a diet, sulfasalazine and corticosteroids. 相似文献
124.
Ariana M.P. Nap Yvonne W.E.A. Pollak Walter E. van den Brom Ad Rijnberk DVM PhD 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1994,8(4):302-303
Thyroidal 99m TcO4 (pertechnetate) uptake percentages were determined in unanesthetized euthyroid (n = 13) and hyperthyroid (n = 18) cats. Maximal uptakes were observed 60 minutes after IV injection of the radionuclide and ranged from 0.3 to 3.9% of the dose in euthyroid cats (median 2.23%) and from 5.2% to 23.9% of the dose in hyperthyroid cats (median 14.8%) ( P < .05). There were no overlaps in pertechnetate uptake percentages during any of the intervals evaluated. It is concluded that the optimal time for visualization of the thyroid by 99m TcO4 -scanning is 60 minutes after IV injection of the radionuclide. Calculation of the percentage uptake is of additional diagnostic value. 相似文献
125.
126.
Use of Echinococcus granulosus worm antigens for immunodiagnosis of E. granulosus infection in dogs.
Echinococcus granulosus worm excretory/secretory antigens (WES) were used in ELISA for diagnosis of E. granulosus infection in dogs and compared with protoscolex somatic antigens (PSM). Sera from 224 dogs were tested. There was no correlation between ELISA absorbance values and E. granulosus worm burdens using either antigen. There was a significant linear relationship between absorbance values of sera tested in the ELISA using WES (W-ELISA) and the ELISA using PSM (P-ELISA). However, there was a small but significant difference between the absorbance values of the sera tested against the two antigens. Western blot analysis of WES using sera from E. granulosus-infected and uninfected dogs revealed antigenic components of relative molecular mass (Mr) larger than 94,000, Mr 94,000-68,000 and Mr 43,000-39,000 in worms, and these were specific for E. granulosus and not identified in PSM; these antigenic differences may be responsible for differences in reactivity in ELISA. The sensitivities of W-ELISA and P-ELISA were 80.8% and 75.6%, respectively. The specificities of W-ELISA and P-ELISA were 93.7% and 97.9%, respectively. The reduced specificity in W-ELISA was mainly attributable to increased background reactivity of sera from Taenia hydatigena-infected dogs. Despite the reduction in specificity, both ELISAs are valuable epidemiological tools to determine the prevalence of antibody to E. granulosus in dog populations and to monitor the success of hydatid control campaigns. 相似文献
127.
128.
Holly L. Jordan DVM Carol B. Grindem DVM PhD Edward B. Breitschwerdt DVM 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1993,7(5):261-265
The prevalence of feline thrombocytopenia (<200,000 platelets/L) at North Carolina State University, College of Veterinary Medicine Teaching Hospital, from January 1985 to March 1990, was 1.2% (41/3300). Cats were divided into six categories based on clinical diagnoses: 29% (12/41) had infectious disease, 20% (8/41) had neoplasia, 7% (3/41) had cardiac disease, 2% (1/41) had primary immune-mediated disease, 22% (9/41) had multiple diseases, and 20% (8/41) had disorders of unknown etiology. The mean platelet count for all thrombocytopenic cats was 52,000/μL ± 46,000/μL (1 SD) with a range of 1000–190,000/μL. No significant differences were found between groups with respect to platelet count, packed cell volume, or white blood cell count, though anemia and leukopenia were common among the cats as a whole. Bleeding disorders (hemorrhage or thrombosis) were observed in 29% (12/41) of thrombocytopenic cats and were more likely to be associated with neoplasia, cardiac disease, and platelet counts less than or equal to 30,000/μL. Disseminated intravascular coagulopathy was diagnosed in 12% (5/41) of the cats. Infections and/or neoplasia affecting the bone marrow were the most common diseases associated with thrombocytopenia. Feline leukemia virus and myeloproliferative neoplasia accounted for approximately 44% (18/41) of the specific diagnoses in thrombocytopenic cats. (Journal of Veterinary Internal Medicine 1993; 7:261–265. Copyright © 1993 by the American College of Veterinary Internal Medicine.) 相似文献
129.
130.
Daniel J. Burba DVM Michael A. Collier DVM Lawrence E. Default PhD Olivia Hanson-Painton PhD Harold C. Thompson Jr. Claude L. Holder 《Journal of Equine Veterinary Science》1993,13(12):696-703
The uptake and distribution of intramuscularly (IM) administered tritium-labeled polysulfated glycosaminoglycan (3H-PSGAG) in serum, synovial fluid, and articular cartilage of eight horses was quantitated, and hyaluronic acid (HA) concentration of the middle carpal joint was evaluated in a pharmacokinetic study. A full-thickness articular cartilage defect, created on the distal articular surface of the left radial carpal bone of each horse served as an osteochondral defect model. 3H-PSGAG (500 mg) was injected IM, between 14 and 35 days after creation of the defects. Scintillation analysis of serum and synovial fluid, collected from both middle carpal joints at specific predetermined times up to 96 hours post-injection, revealed mean 3H-PSGAG concentrations peaked at 2 hours post-injection. 3H-PSGAG was detected in cartilage and subchondral bone 96 hours post-injection in samples from all eight horses. There were no statistically significant differences in 3H-PSGAG concentration of synovial fluid or cartilage between cartilage defect and control (right middle carpal) joints.
HA assay of synovial fluid revealed concentrations significantly increased at 24, 48, and 96 hours post-injection in both joints. The concentration nearly doubled 48 hours post-injection. However, no statistically significant differences were found between synovial concentrations of HA in cartilage defect and control joints.
3H-PSGAG administered IM to horses, was distributed in the blood, synovial fluid, and articular cartilage. HA concentrations in synovial fluid increased after IM administration of polysulfated glycosaminoglycan. 相似文献