全文获取类型
收费全文 | 190328篇 |
免费 | 10606篇 |
国内免费 | 122篇 |
专业分类
林业 | 7619篇 |
农学 | 6149篇 |
基础科学 | 1289篇 |
23702篇 | |
综合类 | 29988篇 |
农作物 | 7166篇 |
水产渔业 | 9562篇 |
畜牧兽医 | 100808篇 |
园艺 | 2444篇 |
植物保护 | 12329篇 |
出版年
2019年 | 1805篇 |
2018年 | 2785篇 |
2017年 | 3122篇 |
2016年 | 2909篇 |
2015年 | 2516篇 |
2014年 | 3088篇 |
2013年 | 7605篇 |
2012年 | 5558篇 |
2011年 | 6729篇 |
2010年 | 4489篇 |
2009年 | 4535篇 |
2008年 | 6591篇 |
2007年 | 6372篇 |
2006年 | 5977篇 |
2005年 | 5484篇 |
2004年 | 5328篇 |
2003年 | 5423篇 |
2002年 | 4977篇 |
2001年 | 6314篇 |
2000年 | 6247篇 |
1999年 | 5014篇 |
1998年 | 1995篇 |
1997年 | 1995篇 |
1996年 | 1870篇 |
1995年 | 2244篇 |
1994年 | 1951篇 |
1993年 | 1932篇 |
1992年 | 4017篇 |
1991年 | 4228篇 |
1990年 | 4152篇 |
1989年 | 4142篇 |
1988年 | 3840篇 |
1987年 | 3887篇 |
1986年 | 3885篇 |
1985年 | 3696篇 |
1984年 | 2977篇 |
1983年 | 2634篇 |
1982年 | 1763篇 |
1979年 | 2628篇 |
1978年 | 2129篇 |
1977年 | 1864篇 |
1976年 | 1776篇 |
1975年 | 1872篇 |
1974年 | 2281篇 |
1973年 | 2415篇 |
1972年 | 2288篇 |
1971年 | 2075篇 |
1970年 | 2064篇 |
1969年 | 1888篇 |
1967年 | 1654篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Testicular regrowths were observed in 10 of 21 tom turkeys between 28 and 32 weeks old, which was between 19 and 23 weeks after surgical caponization at 9 weeks of age. Regrowths were not observed in younger caponized toms. Two types of histologic patterns that differed from the normal pattern were observed in these regrowths. The first pattern was observed in seven regrowths and was characterized by a higher density of seminiferous tubules and more interstitial cells. The second pattern was seen in three regrowths and was characterized by extensive intertubular fibrosis, tubular detachment, and an increased number of interstitial cells. No correlation was found between the presence of these regrowths and plasma testosterone levels. The interstitial cell hyperplasia in all regrowths possibly was related to a diminished negative feedback by the endogenous testosterone on the release of luteinizing hormone from the pituitary. The appearance of regrowths at this age probably was related to the onset of normal physiological puberty. 相似文献
962.
S D White R A Rosychuk T A Janik P Denerolle P Schultheiss 《Journal of the American Veterinary Medical Association》1992,200(9):1377-1380
Clinical signs, laboratory findings, and treatment results of 40 cats with the histologic diagnosis of plasma cell stomatitis-pharyngitis are discussed. Median age was 7.1 years, with no discernable sex predilection. Anorexia and difficulty prehending food were the most common clinical signs. Hyperproteinemia with associated hyperglobulinemia was the most common laboratory finding. Of various treatments, administration of corticosteroids or injectable gold (aurothioglucose) proved most effective in controlling the clinical signs. 相似文献
963.
964.
Fourteen cases of intrapericardial neoplasia seen over a three year period are reviewed. The clinical details and the electrocardiographic, radiographic and laboratory findings are summarised. The usefulness of two-dimensional echocardiography in the diagnosis of intrapericardial mass lesions is emphasised. The prognosis was generally very poor, even in cases in which surgery was performed. 相似文献
965.
Two adult male labrador dogs had short clinical histories of congestive cardiac failure lasting only six weeks. Cardiac function deteriorated rapidly in both dogs, in spite of symptomatic treatment with cardiac glycoside, diuretic and p-adrenergic blocker. Necropsies revealed ascites and pulmonary congestion, but no macroscopic evidence of valvular or myocardial disease adequate to account for the cardiac dysfunction. Both dogs had extensive stenosis of extramural coronary arteries. This unusual vascular lesion comprised fibroelastic intimal thickening, discontinuity of internal elastic lamella and focal atrophy of medial smooth muscle. It seems likely that cardiac failure in these dogs was associated with myocardial underperfusion caused by extensive non-thrombotic, non-atherogenic stenosis of extramural coronary arteries. 相似文献
966.
967.
968.
Unsuccessful attempts to transmit scrapie by nematode parasites 总被引:2,自引:0,他引:2
969.
D W Tarry 《British poultry science》1968,9(4):323-328
The lesser house fly Fannia canicularis and other species of fly of animal health and public health importance, were shown to be attracted to “ black‐light “ traps in semi‐open poultry houses permitting free access and strong daylight competition. The fly populations were reduced and the number of ovipositions in the droppings pit apparently decreased. It is shown that the use of these traps, normally reserved for indoor insect control, can be extended to include certain farm situations. 相似文献
970.