全文获取类型
收费全文 | 3404篇 |
免费 | 196篇 |
国内免费 | 2篇 |
专业分类
林业 | 126篇 |
农学 | 52篇 |
基础科学 | 16篇 |
309篇 | |
综合类 | 590篇 |
农作物 | 101篇 |
水产渔业 | 101篇 |
畜牧兽医 | 2121篇 |
园艺 | 49篇 |
植物保护 | 137篇 |
出版年
2021年 | 37篇 |
2020年 | 42篇 |
2019年 | 43篇 |
2018年 | 47篇 |
2017年 | 57篇 |
2016年 | 46篇 |
2015年 | 49篇 |
2014年 | 62篇 |
2013年 | 140篇 |
2012年 | 126篇 |
2011年 | 146篇 |
2010年 | 84篇 |
2009年 | 61篇 |
2008年 | 147篇 |
2007年 | 125篇 |
2006年 | 109篇 |
2005年 | 119篇 |
2004年 | 127篇 |
2003年 | 123篇 |
2002年 | 113篇 |
2001年 | 75篇 |
2000年 | 85篇 |
1999年 | 80篇 |
1998年 | 43篇 |
1997年 | 25篇 |
1992年 | 83篇 |
1991年 | 88篇 |
1990年 | 75篇 |
1989年 | 72篇 |
1988年 | 68篇 |
1987年 | 62篇 |
1986年 | 62篇 |
1985年 | 61篇 |
1984年 | 48篇 |
1983年 | 38篇 |
1982年 | 29篇 |
1981年 | 36篇 |
1979年 | 44篇 |
1978年 | 40篇 |
1977年 | 29篇 |
1976年 | 25篇 |
1975年 | 22篇 |
1974年 | 42篇 |
1973年 | 38篇 |
1972年 | 40篇 |
1971年 | 37篇 |
1970年 | 37篇 |
1969年 | 52篇 |
1967年 | 23篇 |
1966年 | 28篇 |
排序方式: 共有3602条查询结果,搜索用时 8 毫秒
101.
Johnson EH Al-Busaidy R Hameed MS 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2003,50(2):102-104
Stenotrophomonas maltophilia is a commonly isolated organism from human clinical specimens and is gaining significance as a pathogen in immunocompromised patients and nosocomial infections. In most cases it is difficult to establish the source of human infections. In veterinary medicine, S. maltophilia is not generally considered a primary pathogen. In the present study, we report the occurrence of 16 cases of caprine abscess from which S. maltophilia was isolated in pure culture from 15 animals. In six animals, the abscesses were confined to the pre-scapular lymph nodes but in the remaining nine, the cutaneous abscesses were multiple and extended from the neck to the inguinal area. The possibility is suggested that goats in Oman, which often live in close proximity to humans, might potentially serve as a reservoir of infection. 相似文献
102.
动物精子的性别可通过流式精子分选仪和DNA标识进行鉴定,而利用鉴定性别的精子(即性控精子)并借助人工授精技术或其它授精技术产生的后代,在过去5年中估计已多达30000个(其中大多数是母牛)。有关文献资料证明,能有效地区分X精子和Y精子的唯一标记物是精子染色体中的DNA。众所周知,目前世界各地采用的方法是Beltsville精子分选技术,该技术根据X精子群和Y精子群中DNA相对含量上的差异,用荧光染液(Hoechst33342染液)标记精子,随后利用流式细胞仪分选经荧光标记的精子,从而达到分离精子的目的。目前,X精子或Y精子正常的生产速度是每小时1500万个,该项技术已在家畜、实验动物和动物园动物中应用,如果将该技术应用在人上,在预选后代性别比例上可达90%~95%的成功率。因动物品种不同,性控精子在动物体内的授精部位也不相同。常规的人工授精技术、宫内授精技术、输卵管内授精技术、用于胚胎移植的体外受精(in-vitro fertilization,IVF)技术或子宫角深部授精技术均能有效地使动物怀孕,至于利用哪种技术进行性控精子的精则取决于动物品种。尽管所有动物都能获得高纯度的分选精子,但是在实际生产中利用低剂量精子还难以让母猪怀孕。子宫角深部授精技术每次授精0.5~1.00亿个性控精子已能产生可喜的效果:利用特制的输精管,输入常规人工授精所需精子量的五十分之一的性控精子,足以使动物怀孕。性控精子通过常规的授精技术能够被猪成功利用前,还需重新设计输精管,同时输精的次数和每次授精时精子数量也需作进一步的研究。分选精子的低温保存技术已被牛人工授精普遍采用。尽管已能利用冷冻的性别分选精子生产小猪,但是性别分选精子经冷冻和解冻处理后在常规生产中的应用还未达到最理想的效果。本文将讨论猪精子性别分选的最新研究成果及其发展趋势,并重点探讨将性别分选技术应用于养猪生产中必须对其进行必要的技术开发。 相似文献
103.
Tuntivanich N Petersen-Jones SM Steibel JP Johnson C Forcier JQ 《Veterinary ophthalmology》2007,10(1):2-5
OBJECTIVE: The objectives of this study were to document the development of axial globe length (AGL) in normal mesocephalic cross-bred dogs between 2 and 52 weeks of age, to determine a relationship between AGL and age, and derive an equation to predict AGL in normal mesocephalic cross-bred dogs. ANIMALS STUDIED AND PROCEDURE: The AGL of twenty normal mesocephalic cross-bred dogs was measured at 12 time points from 2 to 52 weeks of age using B-scan ultrasonography. RESULTS: The mean (+/- SEM) AGL increased from 12.65 mm (+/- 0.18) at 2 weeks of age to 19.52 mm (+/- 0.18) at 52 weeks of age. The correlation between AGL and age was evaluated by fitting possible variables to a regression pattern. A linear model of natural logarithmic-transformed value of AGL (mm) and age (week) was established. Side (left or right eye) and gender did not correlate with development of AGL. CONCLUSIONS: A reverse transformation of the formula can be used to predict AGL in mesocephalic cross-bred dogs: AGL = 10.847 * age in weeks 0.1653. 相似文献
104.
105.
Jane Oakey Judy Forbes-Faulkner Christopher Gilpin Bronwyn Murdoch Steven Johnson 《Journal of veterinary diagnostic investigation》2005,17(4):378-382
In 2003, a steer carcass was condemned at a Central Queensland abattoir because of metastatic tumors. In addition, a granulomatous lesion was found in the mediastinal lymph node. Histological examination showed this to be a pyogranuloma, typically associated with Rhodococcus or the Nocardia/Streptomyces group. However, in this case, the only etiological agent was an acid-fast bacillus, which would normally be associated with a more fibrous lesion. A number of nucleic acid-based techniques were used, and the isolate was identified as Mycobacterium asiaticum. This organism is a rarely encountered opportunistic pathogen of humans, associated with subtropical climates. This is the first report of this organism causing infection in cattle. The similarities between this case and cases of human disease are discussed. 相似文献
106.
Frye MA Johnson JS Traub-Dargatz JL Savage CJ Fettman MJ Gould DH 《Journal of the American Veterinary Medical Association》2001,218(4):560-566
OBJECTIVE: To determine historical, physical examination, clinicopathologic, and postmortem findings in horses with putative uremic encephalopathy. Design-Retrospective study. Animals-5 horses with renal failure and neurologic disease not attributable to abnormalities in any other organ system. PROCEDURE: Medical records from 1978 to 1998 were examined for horses with renal disease and neurologic signs not attributable to primary neurologic, hepatic, or other diseases. Signalment, history, physical examination findings, clinicopathologic data, renal ultrasonographic findings, and postmortem data were reviewed. RESULTS: Of 332 horses with renal disease, 5 met selection criteria. Historical findings, physical examination findings, clinicopathologic data, ultrasonographic data, and postmortem findings were consistent with chronic renal failure. Swollen astrocytes were detected in all 4 horses examined at necropsy. CONCLUSIONS AND CLINICAL RELEVANCE: A single criterion was not determined to be pathognomonic for uremic encephalopathy in horses. Uremic encephalopathy should be considered as a differential diagnosis in horses with evidence of chronic renal failure and encephalopathic neurologic sign not attributable to other causes. Astrocyte swelling, which was common to all 4 horses examined at necropsy, may serve as a microscopic indicator of uremic encephalopathy in horses. 相似文献
107.
An adult horse was euthanatized following a clinical diagnosis of cauda equina neuritis. Significant gross postmortem and histopathologic findings were limited to the sacral spinal cord and cauda equina. The sacral spinal cord, meninges, and spinal nerve roots were expanded and partially effaced by sclerosing granulomatous inflammation with necrosis. The lesion contained numerous nematode larvae and fewer adults with a rhabditiform esophagus having a corpus, isthmus, and valved bulb. Female nematodes were amphidelphic and didelphic with reflexed ovaries. These morphologic features confirm Halicephalobus gingivalis as a novel cause of clinical signs in this case of cauda equina neuritis. 相似文献
108.
109.
110.
Cecilia Rohdin Douglas Gilliam Caroline A. O’Leary Dennis P. O’Brien Joan R. Coates Gary S. Johnson Karin Hultin J?derlund 《Acta veterinaria Scandinavica》2015,57(1)