全文获取类型
收费全文 | 115224篇 |
免费 | 5870篇 |
国内免费 | 77篇 |
专业分类
林业 | 5051篇 |
农学 | 3659篇 |
基础科学 | 589篇 |
12790篇 | |
综合类 | 21725篇 |
农作物 | 4292篇 |
水产渔业 | 5604篇 |
畜牧兽医 | 59144篇 |
园艺 | 1393篇 |
植物保护 | 6924篇 |
出版年
2018年 | 1462篇 |
2017年 | 1568篇 |
2016年 | 1486篇 |
2015年 | 1260篇 |
2014年 | 1540篇 |
2013年 | 4054篇 |
2012年 | 2723篇 |
2011年 | 3434篇 |
2010年 | 2287篇 |
2009年 | 2172篇 |
2008年 | 3364篇 |
2007年 | 3325篇 |
2006年 | 3067篇 |
2005年 | 2926篇 |
2004年 | 2851篇 |
2003年 | 2859篇 |
2002年 | 2651篇 |
2001年 | 3642篇 |
2000年 | 3664篇 |
1999年 | 2959篇 |
1998年 | 1156篇 |
1997年 | 1119篇 |
1995年 | 1316篇 |
1994年 | 1081篇 |
1993年 | 1068篇 |
1992年 | 2380篇 |
1991年 | 2531篇 |
1990年 | 2589篇 |
1989年 | 2493篇 |
1988年 | 2339篇 |
1987年 | 2359篇 |
1986年 | 2366篇 |
1985年 | 2281篇 |
1984年 | 1871篇 |
1983年 | 1673篇 |
1982年 | 1085篇 |
1979年 | 1732篇 |
1978年 | 1372篇 |
1977年 | 1198篇 |
1976年 | 1131篇 |
1975年 | 1271篇 |
1974年 | 1619篇 |
1973年 | 1636篇 |
1972年 | 1679篇 |
1971年 | 1547篇 |
1970年 | 1439篇 |
1969年 | 1379篇 |
1968年 | 1157篇 |
1967年 | 1221篇 |
1966年 | 1097篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
H J Bengelsdorff 《Berliner und Münchener tier?rztliche Wochenschrift》1989,102(6):193-198
In the course of vaccine controls, the potency of 25 foot-and-mouth disease (FMD) vaccines was tested quantitatively in parallel in cattle using the intradermal infection and the determination of the SN titres. More than 95% of the vaccinated cattle with SN titres of greater than 1:20 were protected from generalized FMD, regardless of the virus type tested. 61.5% of the vaccinated cattle with SN titres less than or equal to 1:20 were not protected and developed generalized FMD. Comparison of the PD50 values calculated from the results of the intradermal infection and the corresponding SN titres (minimum protection titre greater than 1:20) showed that the results were in complete agreement in 56% of the tested vaccines. In a further 32% of vaccines, the PD50 calculated from the SN titre was slightly below that for the intradermal infection, in the remaining 12% it was somewhat above. The possibility of using the minimum titre determination for testing a vaccine and the significance of this titre as an expression of protection by vaccination are discussed. 相似文献
122.
123.
Blomquist HL 《Science (New York, N.Y.)》1938,88(2272):59-60
124.
125.
126.
127.
128.
L C Savon M Alonso J Rodriguez-Diego T Blandino 《Revue d'élevage et de médecine vétérinaire des pays tropicaux》1992,45(1):30-31
The attenuation of a Babesia bovis strain depends on its protease content. The present work evaluates this parameter on a virulent strain, before and after attenuation by quick passages on splenectomized calves. The protease activity at different pH values was determined in protein fractions from the blood of calves. The enzymatic test showed marked differences between the protease content of both substrains. 相似文献
129.
L Mishu G Callahan Z Allebban J M Maddux T C Boone L M Souza C D Lothrop 《Journal of the American Veterinary Medical Association》1992,200(12):1957-1964
Recombinant canine granulocyte colony-stimulating factor (rcG-CSF) was administered to clinically normal dogs, cyclic-hematopoietic dogs, and dogs undergoing autologous bone marrow transplantation, to determine whether rcG-CSF could be used to stimulate WBC production and function in normal and neutropenic dogs. To the normal dogs, rcG-CSF was administered by SC injection at rates of 1 microgram/kg of body weight, q 12 h; 2 micrograms/kg, q 12 h; or 5 micrograms/kg, q 12 h. A significant dose-dependent increase in the WBC count resulted from the stimulation of bone marrow progenitor cells. The increased WBC count was characterized by mature neutrophilia and monocytosis. Neutrophil myeloperoxidase and phagocytic activity were normal in rcG-CSF-treated normal dogs, demonstrating the production of normal functional neutrophils in response to rcG-CSF treatment. Recombinant canine G-CSF prevented neutropenia and associated clinical signs but did not completely eliminate the cycling of neutrophils in cyclic-hematopoietic dogs when it was administered at rates of 1 microgram/kg, q 12 h, and 2.5 micrograms/kg, q 12 h. The time to bone marrow reconstitution was not decreased in dogs treated with rcG-CSF at a rate of 2.5 micrograms/kg, q 12 h, for 13 days following autologous bone marrow transplantation. On the basis of our findings, we suggest that treatment with rcG-CSF is an effective way to stimulate myelopoiesis in dogs, but that the dose of rcG-CSF required to stimulate WBC production will vary depending on the cause of neutropenia. Recombinant canine G-CSF should be useful in stimulating production and maintaining function of WBC for treatment of clinical diseases seen commonly in veterinary practice. 相似文献
130.
Russell T. Greene Gregory C. Troy 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1995,9(2):86-91
Coccidioidomycosis was diagnosed in 48 cats. Forty-one cases were identified within a period of 3 years. Coccidioides immitis was revealed by cytological or histopathological examinations, or culture in 70% of cats. The remaining 30% of cases were diagnosed by appropriate clinical signs, radiographic lesions, and serological test results. The average age of affected cats was 6.2 years with a median age of 5.0 years. Fifty-four percent (n = 26) were female and 46% (n = 22) were male. Domestic shorthaired and longhaired breeds comprised 89% (n = 41) of affected cats. Sixty-seven percent of cases were diagnosed during the 6-month period of December through May. Cats infected with C immitis were presented for evaluation of dermatologic (56%), respiratory (25%), musculoskeletal (19%), and neurological or ophthalmologic signs (19%). Fever, inappetence, and weight loss were present in 44% of the cats. Duration of clinical signs before diagnosis was less than 4 weeks in 85% (n = 42) of cats, with an average of 3.8 weeks and a median of 2 weeks. Agar gel immunodiffusion tests were positive in all 39 cats tested at sometime during the course of their disease. Hyperproteinemia (greater than 7.9 g/dL) was present in 52% (10/23) of cases. The majority of cats (n = 39) were negative for feline leukemia virus. Antibodies to feline immunodeficiency virus were absent in the 19 cats tested. Ketoconazole was the most common antifungal agent used to treat cats with Coccidioidomycosis. Duration of treatment ranged from less than 1 week to 43 months. Thirty-two cats are currently asymptomatic, with or without treatment. Eleven cats died or were euthanized. Five cats were lost to follow-up. Ketoconazole likely is more suppressive than curative because relapses were common after discontinuing therapy. 相似文献