全文获取类型
收费全文 | 208610篇 |
免费 | 7604篇 |
国内免费 | 110篇 |
专业分类
林业 | 8141篇 |
农学 | 6803篇 |
基础科学 | 1502篇 |
24919篇 | |
综合类 | 34582篇 |
农作物 | 7732篇 |
水产渔业 | 10555篇 |
畜牧兽医 | 105357篇 |
园艺 | 2614篇 |
植物保护 | 14119篇 |
出版年
2018年 | 2819篇 |
2017年 | 3174篇 |
2016年 | 2967篇 |
2015年 | 2543篇 |
2014年 | 3114篇 |
2013年 | 8008篇 |
2012年 | 5687篇 |
2011年 | 7023篇 |
2010年 | 4536篇 |
2009年 | 4493篇 |
2008年 | 6890篇 |
2007年 | 6483篇 |
2006年 | 6349篇 |
2005年 | 5678篇 |
2004年 | 5542篇 |
2003年 | 5593篇 |
2002年 | 5335篇 |
2001年 | 6631篇 |
2000年 | 6454篇 |
1999年 | 5146篇 |
1998年 | 2087篇 |
1997年 | 2190篇 |
1996年 | 1983篇 |
1995年 | 2388篇 |
1994年 | 2165篇 |
1993年 | 2073篇 |
1992年 | 4252篇 |
1991年 | 4422篇 |
1990年 | 4451篇 |
1989年 | 4413篇 |
1988年 | 4010篇 |
1987年 | 4094篇 |
1986年 | 4159篇 |
1985年 | 4017篇 |
1984年 | 3353篇 |
1983年 | 2966篇 |
1982年 | 2065篇 |
1981年 | 1900篇 |
1979年 | 3035篇 |
1978年 | 2465篇 |
1977年 | 2087篇 |
1976年 | 1954篇 |
1975年 | 2129篇 |
1974年 | 2698篇 |
1973年 | 2704篇 |
1972年 | 2606篇 |
1971年 | 2399篇 |
1970年 | 2268篇 |
1969年 | 2140篇 |
1967年 | 1876篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Examinations were made of three sections of trachea obtained from eight dogs. The sections examined were at the regions of the second ring caudal to the larynx, the thoracic inlet, and the origin of the brachiocephalic trunk. Measurements were made of the lateral and ventrodorsal diameters, the lumen area of the trachea, the width and thickness of the tracheal cartilages, and the thickness of the trachealis muscle. Cell counts-per-square-micrometer of the cartilage and trachealis muscle were made. The results of these measurements were subjected to statistical analyses by means of one-way and two-way analyses of variance. The tracheal diameters, cartialge thickness, muscle thickness, and tracheal lumen area had significantly different measurements among the areas compared with both statistical methods. Ventrodorsal tracheal diameter and lumen area were not found to have significantly different measurements between the levels of the thoracic inlet and the brachiocephalic trunk. The cell counts did not have significantly different values among the areas considered when body weight was not a factor, but the values were significant when weight was a factor. 相似文献
993.
B. J. Aarons 《Australian veterinary journal》1979,55(3):146-148
SUMMARY: Modern treatment of hydatid disease of man depends on confirmation of active disease by use of modern serological tests, accurate identification of anatomical sites followed by complete removal of the parasite without spillage, and sterilisation of the remaining cavity. To avoid spillage use of a hydatid cone is recommended. 相似文献
994.
SURGICAL repair of the patent ductus arteriosus (PDA) is one of the most common cardiovascular procedures performed in veterinary and human medicine.1–3 The techniques have been well documented and used successfully.2–5 相似文献
995.
A progressive axonopathy of Boxer dogs affecting the central and peripheral nervous systems 总被引:1,自引:0,他引:1
Five Boxer dogs with a new neurological disease are described. There is a progressive ataxia and weakness, initially in the hind-legs but later involving forelegs. The onset of signs is usually around 6 months of age although an older dog was affected. Proprioceptive function, muscle tone and tendon reflexes are diminished or absent while pedal reflexes and pain sensation are preserved. Muscle atrophy is minimal. The peripheral nerves are depleted in myelinated fibres. Nerve roots and, to a lesser extent, peripheral nerves show demyelination/remyelination changes and in the cervical ventral roots in particular, regenerative clusters are present. Forelimb muscles show evidence of re-innervation. In the CNS numerous swollen axons are present. The dorsolateral and ventral columns of the spinal cord are affected throughout their length. In the brain a number of nuclei and tracts, particularly in the lower brain stem, are affected and the superior olives are severely involved. The cerebral cortex and subcortical white matter appear normal. Various portions of the auditory and optic pathways are affected pathologically as are a number of cranial nerves. The axonal swellings contain a number of organelles including smooth endoplasmic reticulum, disordered neurofilaments, vesicles and mitochondria. The disease may be specific to Boxer dogs and may be inherited. 相似文献
996.
Epidemiologic study of campylobacteriosis in Iowa cattle and the possible role of unpasteurized milk as a vehicle of infection 总被引:3,自引:0,他引:3
Bile samples were collected from 477 Iowa dairy cows and were cultured for thermophilic campylobacters. The prevalence of thermophilic campylobacters in the bile was 15.5%. Campylobacter jejuni and C coli from dairy cattle, chickens, pigs, sheep, and human beings were serotyped to develop host-species profiles. Human and cattle serologic profiles were the most similar, and human and chicken profiles shared several similarities. Epidemiologic data from 168 human cases of campylobacteriosis indicated that 23% of the cases were associated with consumption of unpasteurized milk. 相似文献
997.
998.
999.
1000.