全文获取类型
收费全文 | 196386篇 |
免费 | 10362篇 |
国内免费 | 126篇 |
专业分类
林业 | 8220篇 |
农学 | 5904篇 |
基础科学 | 1302篇 |
22263篇 | |
综合类 | 36616篇 |
农作物 | 7481篇 |
水产渔业 | 9515篇 |
畜牧兽医 | 99938篇 |
园艺 | 2428篇 |
植物保护 | 13207篇 |
出版年
2018年 | 2322篇 |
2017年 | 2523篇 |
2016年 | 2378篇 |
2015年 | 2099篇 |
2014年 | 2567篇 |
2013年 | 7027篇 |
2012年 | 4804篇 |
2011年 | 6002篇 |
2010年 | 3815篇 |
2009年 | 3799篇 |
2008年 | 5929篇 |
2007年 | 5766篇 |
2006年 | 5513篇 |
2005年 | 5176篇 |
2004年 | 5045篇 |
2003年 | 5070篇 |
2002年 | 4892篇 |
2001年 | 5994篇 |
2000年 | 5843篇 |
1999年 | 4822篇 |
1998年 | 1928篇 |
1997年 | 1957篇 |
1995年 | 2263篇 |
1994年 | 1976篇 |
1993年 | 1954篇 |
1992年 | 4057篇 |
1991年 | 4247篇 |
1990年 | 4374篇 |
1989年 | 4345篇 |
1988年 | 4014篇 |
1987年 | 4080篇 |
1986年 | 4191篇 |
1985年 | 4070篇 |
1984年 | 3423篇 |
1983年 | 3059篇 |
1982年 | 2117篇 |
1981年 | 1952篇 |
1980年 | 1868篇 |
1979年 | 3134篇 |
1978年 | 2580篇 |
1977年 | 2212篇 |
1976年 | 2028篇 |
1975年 | 2191篇 |
1974年 | 2871篇 |
1973年 | 2955篇 |
1972年 | 2916篇 |
1971年 | 2649篇 |
1970年 | 2500篇 |
1969年 | 2273篇 |
1967年 | 1980篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
Disseminated Aspergillus terreus infection was diagnosed in ten previously healthy adult dogs--nine German shepherds and one dalmatian. The disease was characterized by the presence of multiple granulomas and infarcts in a wide range of organs. The kidney, spleen, and skeletal system were most commonly and severely affected. Fungal hyphae were demonstrated in large numbers within granulomas and thrombi, and A. terreus was readily isolated by culture. This disseminated mycosis appears unique; in this series of cases there was no apparent predisposing factor, portal of entry, or primary focus for dissemination of the infection. 相似文献
75.
B J Culliton 《Science (New York, N.Y.)》1989,245(4919):697-698
76.
M P Yang R Goitsuka H Tsujimoto M Onuma A Hasegawa 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1992,54(4):757-761
The association of tumor-associated antigen (TAA) on the proliferation of BLV-infected lymphoblastoid B-cell lines (BL2M3 and BL312) was investigated. Flow cytometric analysis of the expression of TAA with monoclonal antibody (mAb) c143 showed high expression of TAA on the surfaces of BL2M3 and BL312 cells. A large amount of TAA was found in the culture supernatant of BL2M3 and BL312 cells as well as in the lysates of BL2M3 and BL312 cells. Culture supernatant but not lysates of BL2M3 and BL312 cells promoted the growth of either BL2M3 cells or BL312 cells. Furthermore, this growth promoting activity in culture supernatants of BL2M3 and BL312 cells was inhibited in a dose-dependent manner when cultured with mAb c143. These results suggested that TAA may be involved in the growth factor-mediated cell growth of bovine B-lymphoblastoid cell lines expressing TAA on their cell surface. 相似文献
77.
J B Herrick 《Journal of the American Veterinary Medical Association》1992,201(12):1854-1855
78.
1. White blood cell responses of broilers, turkeys and ducks were examined at regular intervals after being subjected to various degrees of food restriction. 2. Restricted-fed broilers showed increases in heterophil and basophil numbers, together with a corresponding decrease in lymphocytes. The heterophil/lymphocyte ratio was raised. There were no differences between broiler strains. 3. After only one week of feeding restricted diets, heterophils were significantly raised in selected and unselected 2-week-old ducks. At 21 weeks of age, those ducks receiving 50% of food required to achieve their ad libitum-fed body weight had raised heterophils. 4. Ducks receiving food to achieve 25% of ad libitum-fed birds produced a marked basophilia, but no heterophilia. 5. After two weeks of food restriction, turkeys responded with significant heterophil/lymphocyte ratios following two degrees of restricted feeding. 6. It was concluded that in some poultry, a heterophilia may be the response to mild to moderate stress but a basophilia may result after severely stressing birds. 相似文献
79.
Xylazine and tiletamine-zolazepam anesthesia in horses 总被引:4,自引:0,他引:4
The cardiopulmonary and anesthetic effects of xylazine in combination with a 1:1 mixture of tiletamine and zolazepam were determined in 6 horses. Each horse was given xylazine IV or IM, as well as tiletamine-zolazepam IV on 4 randomized occasions. Anesthetics were administered at the rate of 1.1 mg of xylazine/kg of body weight, IV, 1.1 mg of tiletamine-zolazepam/kg, IV (treatment 1); 1.1 mg of xylazine/kg, IV, 1.65 mg of tiletamine-zolazepam/kg, IV (treatment 2); 1.1 mg of xylazine/kg, IV, 2.2 mg of tiletamine-zolazepam/kg, IV (treatment 3); and 2.2 mg of xylazine/kg, IM, 1.65 mg of tiletamine-zolazepam/kg, IV (treatment 4). Tiletamine-zolazepam doses were the sum of tiletamine plus zolazepam. Xylazine, when given IV, was given 5 minutes before tiletamine-zolazepam. Xylazine, when given IM, was given 10 minutes before tiletamine-zolazepam. Tiletamine-zolazepam induced recumbency in all horses. Duration of recumbency in group 1 was 31.9 +/- 7.2 (mean +/- 1 SD) minutes. Increasing the dosage of tiletamine-zolazepam (treatments 2 and 3) significantly (P less than 0.05) increased the duration of recumbency. Xylazine caused significant (P less than 0.05) decreases in heart rate and cardiac output and significant (P less than 0.05) increases in central venous pressure and mean pulmonary artery pressure 5 minutes after administration. Respiratory rate was decreased. Arterial blood pressures increased significantly (P less than 0.05) after xylazine was administered IV in treatments 1 and 3, but the increases were not significant in treatment 2. Xylazine administered IM caused significant (P less than 0.05) increases in central venous pressure and significant (P less than 0.05) decreases in cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
80.
Michael J. A. Young Arlo W. Fast Paul G. Olin 《Journal of the World Aquaculture Society》1989,20(1):7-11
Chinese catfish ( Clarias fuscus ) were successfully spawned in Hawaii using human chorionic gonadotropin (HCG) at dosage rates of two and four international units (IU) per gram body weight. Fish not injected with HCG did not produce viable eggs. Successful spawns with HCG occurred between May and October. Hatch rates of up to 80% were obtained during June, July, and August for those fish given either a 2 or 4 IU per gram body weight injection of HCG. Fish spawned in either May or October yielded significantly higher hatch rates when injected with 4 rather than 2 IU per gram body weight. Fish held at elevated temperatures (28 to 30 C) prior to the normal spawning season developed significantly larger oocyte diameters, 60 days earlier than fish held under ambient temperature conditions (21.5 to 24 C). Photoperiod manipulation at ambient temperature conditions was associated with earlier oocyte maturation, but photoperiod effects were much less important than temperature. 相似文献