全文获取类型
收费全文 | 1307篇 |
免费 | 75篇 |
国内免费 | 3篇 |
专业分类
林业 | 29篇 |
农学 | 15篇 |
基础科学 | 11篇 |
103篇 | |
综合类 | 237篇 |
农作物 | 30篇 |
水产渔业 | 93篇 |
畜牧兽医 | 706篇 |
园艺 | 9篇 |
植物保护 | 152篇 |
出版年
2023年 | 10篇 |
2022年 | 23篇 |
2021年 | 29篇 |
2020年 | 24篇 |
2019年 | 23篇 |
2018年 | 18篇 |
2017年 | 31篇 |
2016年 | 22篇 |
2015年 | 22篇 |
2014年 | 17篇 |
2013年 | 53篇 |
2012年 | 54篇 |
2011年 | 47篇 |
2010年 | 45篇 |
2009年 | 44篇 |
2008年 | 58篇 |
2007年 | 56篇 |
2006年 | 45篇 |
2005年 | 34篇 |
2004年 | 33篇 |
2003年 | 37篇 |
2002年 | 35篇 |
2001年 | 28篇 |
2000年 | 20篇 |
1999年 | 26篇 |
1998年 | 22篇 |
1997年 | 15篇 |
1996年 | 23篇 |
1995年 | 17篇 |
1994年 | 14篇 |
1993年 | 23篇 |
1992年 | 21篇 |
1991年 | 22篇 |
1990年 | 20篇 |
1989年 | 22篇 |
1988年 | 14篇 |
1987年 | 20篇 |
1986年 | 11篇 |
1985年 | 16篇 |
1984年 | 13篇 |
1981年 | 15篇 |
1980年 | 15篇 |
1979年 | 18篇 |
1978年 | 12篇 |
1976年 | 16篇 |
1974年 | 9篇 |
1973年 | 9篇 |
1972年 | 11篇 |
1971年 | 12篇 |
1969年 | 9篇 |
排序方式: 共有1385条查询结果,搜索用时 15 毫秒
101.
102.
B. M. Freeman 《British poultry science》1985,26(2):141-145
The first issue of British Poultry Science was published in April 1960. In this paper the origin and development of the Journal and the organisations with which it has been associated are traced. 相似文献
103.
An international effort (sponsored by the Australian Centre for International Agricultural Research) is being made to develop oral vaccines that will protect village chickens against Newcastle disease. The vaccines being used are derivatives of the avirulent Australian V4 strain that have been selected for enhanced heat resistance. The present study, undertaken in Sri Lanka, used local processed (parboiled) rice as a vehicle for the vaccine. Chickens receiving two doses of vaccine on cooked, parboiled rice were completely protected against contact challenge with the virulent SL 88/1 Sri Lankan strain of Newcastle disease virus Chickens kept in contact with these vaccinated chickens were similarly protected. Lower levels of protection were achieved with vaccine given on uncooked parboiled rice. V4 vaccine administered intranasally also gave complete protection. Serums from vaccinated chickens that survived challenge were tested for haemagglutination-inhibition antibodies, using both vaccine virus and challenge virus as antigens. Titres were higher against vaccine virus. 相似文献
104.
T S Ford D E Freeman M W Ross D W Richardson B B Martin J B Madison 《Journal of the American Veterinary Medical Association》1990,196(1):121-126
The case records of 26 horses with ileocecal intussusception over a 7-year period were reviewed to determine clinical features of the disease and response to treatment. The median age of horses with ileocecal intussusception was 1 year and ranged from 2 weeks to 19 years. There was no apparent gender or breed predisposition to this disease. An acute form of ileocecal intussusception was diagnosed in 19 horses with signs of moderate to severe abdominal pain of less than or equal to 24 hours' duration, and a chronic form was diagnosed in 7 horses with signs of intermittent, mild to moderate abdominal pain of more than 3 days' duration. Horses with chronic ileocecal intussusception had a history of weight loss or failure to gain weight, slow growth, poor appetite, low-grade pyrexia, and postprandial signs of abdominal pain. At surgery, the involved segments of intestine (intussusceptum and intussuscipiens) in chronic cases were 2 to 10 cm long, and the ileum and much of the distal portion of the jejunum were flaccid, dilated, and thick walled. In the acute cases, the length of involved intestine ranged from 6 to 457 cm. Whereas only 1 of 7 chronic intussusceptions (14%) could be reduced, 9 of 19 (47%) acute intussusceptions were reducible. Surgical treatment included resection and jejunocecostomy (6 horses), partial resection through a cecotomy and a side-to-side jejunocecostomy (2 horses), and a side-to-side ileocecostomy or jejunocecostomy without resection (12 horses, 7 of which had chronic intussusception). Six horses with acute intussusception were euthanatized before or during surgery.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
105.
106.
107.
Development of cytoplasmic male sterile 《分子植物育种》2007,5(2):215-216
Development of cytoplasmic male sterile (CMS) lines with elongated uppermost internode (EUI) trait provides a genetic option to eliminate the use of GA3 in hybrid rice. During the past two decades, extensive work has been carried out on the subject that resulted in identification of several mutants with EUI trait for use in developing cytoplasmic/thermo-sensitive genic male-sterile lines with complete panicle exsertion (Okuno and Kawai, 1978; Rutger and Carnahan, 1981; Shen et al., 1987; Yang et al., 2000; 2002; Gangashetti et al., 2004). Two recessive genes (eui-1 and eui-2) mapped on chromosome 5 and 10 respectively have so far been reported to control the internode elongation in rice (Librojo and Khush, 1986; Yang et al., 2001; Ma et al., 2004). Considerable progress has been made in China in exploiting 'eur gene for development of hybrid rice parental lines (Yang et al., 2000; 2002; Zhang et al., 2002). 相似文献
108.
A survey of Iowa farmers was conducted to assess the farmers' perceptions and beliefs regarding auger safety and how these perceptions are put into practice. A questionnaire was designed to obtain information on the following auger-related topics: recognition of safe practices and appropriate shielding, personal practices and behaviors, risk perception, and personal beliefs. A random sample of 400 Iowa farmers (arrayed by county) was selected to be representative of Iowa farms. The response to the mailed survey was 23%. Some returned surveys were eliminated because the respondent was retired or did not own/operate augers, resulting in 57 usable questionnaires. Survey responses indicate that the majority of Iowa farmers who participated in this study can correctly identify appropriate shielding for auger intake that meet or exceed ASAE standards. Survey responses suggest that it is common practice in Iowa for youth (age 13 to 19) to operate augers. Iowa farmers in this study perceive the most important contributing factors to auger-related injuries to be operating an auger without shielding, failure to pay attention on the job, moving augers in a raised position, and using hand or feet to redirect the flow of grain. Survey results also indicate that carelessness is perceived to be the leading cause of auger-related injuries, and that auger related injuries can be avoided by having respect for the equipment, being careful, and using common sense. The results also show that the Iowa farmers who participated in this study commonly perform auger-related practices (e.g., moving an auger in a raised position) that they identify as being unsafe. 相似文献
109.
110.