全文获取类型
收费全文 | 186404篇 |
免费 | 10136篇 |
国内免费 | 187篇 |
专业分类
林业 | 8815篇 |
农学 | 6028篇 |
基础科学 | 1219篇 |
23783篇 | |
综合类 | 30578篇 |
农作物 | 7329篇 |
水产渔业 | 9254篇 |
畜牧兽医 | 94524篇 |
园艺 | 2593篇 |
植物保护 | 12604篇 |
出版年
2019年 | 1753篇 |
2018年 | 2711篇 |
2017年 | 3019篇 |
2016年 | 2811篇 |
2015年 | 2401篇 |
2014年 | 2945篇 |
2013年 | 7373篇 |
2012年 | 5465篇 |
2011年 | 6652篇 |
2010年 | 4345篇 |
2009年 | 4420篇 |
2008年 | 6512篇 |
2007年 | 6218篇 |
2006年 | 5763篇 |
2005年 | 5415篇 |
2004年 | 5152篇 |
2003年 | 5322篇 |
2002年 | 4828篇 |
2001年 | 5614篇 |
2000年 | 5609篇 |
1999年 | 4494篇 |
1998年 | 1974篇 |
1997年 | 1911篇 |
1996年 | 1766篇 |
1995年 | 2128篇 |
1994年 | 1850篇 |
1993年 | 1756篇 |
1992年 | 3582篇 |
1991年 | 3842篇 |
1990年 | 3741篇 |
1989年 | 3785篇 |
1988年 | 3466篇 |
1987年 | 3389篇 |
1986年 | 3529篇 |
1985年 | 3382篇 |
1984年 | 2828篇 |
1983年 | 2482篇 |
1982年 | 1723篇 |
1979年 | 2630篇 |
1978年 | 2071篇 |
1977年 | 1807篇 |
1976年 | 1826篇 |
1975年 | 1939篇 |
1974年 | 2306篇 |
1973年 | 2367篇 |
1972年 | 2215篇 |
1971年 | 2094篇 |
1970年 | 2028篇 |
1969年 | 2004篇 |
1967年 | 1802篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
891.
892.
F.W.G. Hill B.A. Christie W.T. Reynolds R.B. Lavelle 《Australian veterinary journal》1979,55(4):184-187
An 11-month-old male Miniature Poodle was found to regurgitate small volumes of fluid and food particles due to a diverticulum in the thoracic oesophagus. The diverticulum was removed surgically. Histologically the wall contained extensive scar tissue. Longterm recovery was uneventful and 5 months after surgery the dog is in good health 相似文献
893.
894.
The effects of sufficient milk intake as well as of 32 hours of fasting after birth, administration of actinomycin D (intraperitoneal application of 1 mg/kg five weight), and fasting in combination with actinomycin D on the development of body and liver weights, crude protein levels in homogenate and supernatant of liver, kidneys, and M. semitendinosus as well as on the activities of certain tissue enzymes were analysed with four groups of piglets (n = 4). Fasting, administration of actinomycin, and fasting in combination with actinomycin D resulted in rapid reduction in body and liver weights, while the crude protein levels in those tissues were not affected with significance. GOT and fructose-1,6-diphosphatase activities in supernatant from liver tended to decline under fasting conditions. The ATPase activity in the homogenate of the above tissues did not change in response to differentiated treatment. 相似文献
895.
896.
J L Shupe N C Leone A E Olson E J Gardner 《American journal of veterinary research》1979,40(6):751-757
Investigation of hereditary multiple exostoses in horses under controlled research conditions for 10 years and epidemiologic studies that have spanned up to five generations of human families contain notable similarities. The present study demonstrated that a single dominant autosomal gene is responsible for hereditary multiple exostoses in horses and man. Affected individuals transmit this trait to approximately 50% of their progeny, whereas nonaffected individuals do not transmit the condition to their offspring. The tumors in affected horses are most often present at birth. They tend to be bilaterally symmetrical and vary in size, shape, and texture. Those on the legs generally do not appear to enlarge as the animal matures, but others, notably those on the ribs and scapulae, enlarge until skeletal maturity, Histologically, the tumors appear as typical ostosteochondromas in both horse and man. Sarcomatous transformations have not yet been detected after 10 years in horses, although such changes are occasionally reported in the similar disease condition in man. The remarkable similarities of hereditary multiple exostoses in the horse to that in man provide an opportunity for comparative biomedical study. 相似文献
897.
Two experiments, using the ligated intestinal segment technique, were conducted to determine whether the pituitary hormone prolactin (PRL) could reduce Escherichia coli-induced fluid loss into the small intestine of 2- to 3-week-old pigs. Inoculation of 10(6) to 10(8) enteropathogenic E coli organisms into ligated jejunal segments caused a significant accumulation of luminal fluid within 12 hours. In the first experiment, intraluminal inoculation with 0.5 mg of ovine PRL along with the bacteria did not have any effect on fluid accumulation. Systemic IV treatment of the animals with 1.0 mg of ovine PRL at 3-hour intervals, beginning either immediately after or 9 to 10 hours before intestinal ligation, did not significantly (P less than 0.05) reduce fluid accumulation as compared with control animals. In the second experiment, IM administration of 100 microgram of thyrotropin-releasing hormone (TRH) at 3-hour intervals, beginning 6 hours before intestinal ligation, significantly (P less than 0.05) increased circulating PRL concentrations, as measured by radioimmunoassay. However, TRH treatment did not reduce the accumulation of luminal fluid in E coli-inoculated segments. 相似文献
898.
Intranuclear cisternal and vesicular structures, bound by a single membrane, were observed for the first time in some glandular "bird's eye" cells of canine circummanal gland carcinomas. The role of these intranuclear structures is not clear. It is suggested that they may be involved in cellular adaptation to an environment of nutrient deficiency, as a result of cell overcrowding. 相似文献
899.
900.