全文获取类型
收费全文 | 1192篇 |
免费 | 74篇 |
国内免费 | 3篇 |
专业分类
林业 | 60篇 |
农学 | 15篇 |
基础科学 | 2篇 |
111篇 | |
综合类 | 170篇 |
农作物 | 28篇 |
水产渔业 | 135篇 |
畜牧兽医 | 687篇 |
园艺 | 18篇 |
植物保护 | 43篇 |
出版年
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 19篇 |
2018年 | 19篇 |
2017年 | 14篇 |
2016年 | 21篇 |
2015年 | 18篇 |
2014年 | 16篇 |
2013年 | 54篇 |
2012年 | 36篇 |
2011年 | 53篇 |
2010年 | 29篇 |
2009年 | 37篇 |
2008年 | 48篇 |
2007年 | 45篇 |
2006年 | 48篇 |
2005年 | 31篇 |
2004年 | 37篇 |
2003年 | 31篇 |
2002年 | 55篇 |
2001年 | 29篇 |
2000年 | 42篇 |
1999年 | 39篇 |
1998年 | 18篇 |
1997年 | 18篇 |
1996年 | 11篇 |
1992年 | 24篇 |
1991年 | 23篇 |
1990年 | 36篇 |
1989年 | 15篇 |
1988年 | 26篇 |
1987年 | 17篇 |
1986年 | 18篇 |
1985年 | 20篇 |
1984年 | 15篇 |
1983年 | 17篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 12篇 |
1979年 | 20篇 |
1978年 | 14篇 |
1977年 | 11篇 |
1975年 | 16篇 |
1974年 | 8篇 |
1973年 | 15篇 |
1972年 | 15篇 |
1971年 | 10篇 |
1970年 | 16篇 |
1969年 | 8篇 |
1968年 | 7篇 |
排序方式: 共有1269条查询结果,搜索用时 0 毫秒
21.
22.
L G Adams D J Polzin C A Osborne T D O'Brien 《American journal of veterinary research》1991,52(5):718-722
The influence of induced chronic renal failure on 24-hour urinary excretion and fractional excretion of sodium and potassium was studied in cats. Induction of chronic renal failure significantly increased fractional excretion of potassium (P less than 0.0001) and sodium (P less than 0.05); however, 24-hour urinary excretion of sodium and potassium decreased slightly following induction of chronic renal failure. Fractional excretion and 24-hour urinary excretion of sodium and potassium were compared by linear regression in clinically normal cats, cats with chronic renal failure, and clinically normal and affected cats combined. In clinically normal cats, linear regression revealed only moderate correlation between fractional excretion and 24-hour urinary excretion for sodium and potassium. Linear regression of these same relationships in cats with chronic renal failure, and in clinically normal cats and cats with chronic renal failure combined, indicated low correlation. Fractional excretions of sodium and potassium were not reliable indicators of 24-hour urinary excretion of these electrolytes in cats with chronic renal failure or unknown glomerular filtration rate. Fractional excretion of potassium and sodium correlated only moderately with 24-hour urinary excretion in clinically normal cats. 相似文献
23.
E W Adams 《Journal of the American Veterinary Medical Association》1979,175(2):207-209
A prototype for the implementation of a comprehensive health maintenance program is described in which the expertise of veterinary medicine is brought to bear on preventive medicine and on special generic environmental disease factors as they impact on human health. For the sake of organization and the ease of presentation, certain specific activities have been divided into two overlapping categories: environmental health and health education. The implementation of a comprehensive health care delivery system will become a reality only when the full array of health resources is matched with health needs. It cannot be overemphasized that the delivery of health care services is not exclusively within the purview of any one profession; rather, interdependence and sharing of responsibilities and activities in a team approach are characteristics of the human health system. 相似文献
24.
25.
26.
27.
28.
29.
Myoelectrical and myomechanical activities of the distal portion of the jejunum and pelvic flexure were studied in 7 ponies, using permanently implanted monopolar and bipolar stainless steel electrodes. Dental acrylic embedded recording electrodes were surgically sutured to the serosal surface of the distal portion of the jejunum and pelvic flexure. Myoelectrically, regular spike bursts and irregular spike bursts were observed in the jejunum. Short spike bursts and long spike bursts were recorded and associated with spike potentials, using impedance recording techniques. Electrical and mechanical data could be monitored simultaneously from the same recording electrode, using separate channels on a physiograph. This method proved effective to monitor periodically myomechanical activity at the same time that myoelectrical activity was being evaluated. The recording system required fewer recording devices to be attached to the intestinal tract, was an inexpensive method of obtaining myomechanical recordings, and did not alter markedly the myoelectrical activity when mechanical activity was being monitored. 相似文献
30.
Aggressive behavior is reduced in bulls actively immunized against gonadotropin-releasing hormone 总被引:5,自引:0,他引:5
The purpose of this research was to compare the frequency of aggressive behavior's in beef bulls actively immunized against gonadotropin-releasing hormone relative to contemporary nonimmunized control bulls and surgically castrated steers. Eight males were assigned to each ofthese treatments in each of 4 yr. Immunized males were treated with a GnRH-keyhole-limpet hemocyanin (KLH) conjugate at approximately 4 mo of age. A secondary (booster) immunization was administered at 12 mo. Steers were castrated at 4 mo of age. Animals in each treatment in each year were housed as a single group prior to testing. At approximately 16 mo of age, each group of eight animals was placed in a 10- x 16-m enclosure for 20 min on five occasions at 2 to 3 d intervals. An observer recorded butts initiated by each animal as well as participation in bouts of sparring. Relative to control bulls, immunocastration reduced the frequency of butts initiated (P < 0.05) and participation in sparring bouts (P < 0.05) to levels typically observed in steers (P > 0.05). These observations indicate that active immunization against GnRH reduces the incidence of aggressive behavior in male beef cattle and are consistent with our postulate that immunoneutralization of GnRH is an effective alternative to surgical castration in the management of beef cattle. 相似文献