全文获取类型
收费全文 | 207篇 |
免费 | 5篇 |
专业分类
林业 | 7篇 |
农学 | 4篇 |
16篇 | |
综合类 | 72篇 |
农作物 | 2篇 |
水产渔业 | 7篇 |
畜牧兽医 | 89篇 |
园艺 | 3篇 |
植物保护 | 12篇 |
出版年
2022年 | 3篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 20篇 |
2012年 | 6篇 |
2011年 | 14篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 13篇 |
2007年 | 7篇 |
2006年 | 13篇 |
2005年 | 10篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1996年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1977年 | 2篇 |
1928年 | 2篇 |
1927年 | 3篇 |
1925年 | 2篇 |
1921年 | 2篇 |
1917年 | 2篇 |
1916年 | 1篇 |
1914年 | 1篇 |
1912年 | 1篇 |
1911年 | 1篇 |
1908年 | 1篇 |
1905年 | 2篇 |
1904年 | 4篇 |
1903年 | 2篇 |
1902年 | 2篇 |
1900年 | 2篇 |
1899年 | 2篇 |
1898年 | 1篇 |
1895年 | 2篇 |
1893年 | 1篇 |
1892年 | 2篇 |
1889年 | 2篇 |
1887年 | 1篇 |
1884年 | 1篇 |
排序方式: 共有212条查询结果,搜索用时 46 毫秒
11.
Christy A McKnight Annabel G Wise Roger K Maes Christopher Howe Annabel Rector Marc Van Ranst Matti Kiupel 《Journal of zoo and wildlife medicine》2006,37(2):193-196
A 5-yr-old female Egyptian fruit bat (Rousettus aegyptiacus) had a small raised pigmented mass removed from the lateral canthus of the left eye. Six additional variably sized, raised, smooth to cauliflower-like skin masses were observed randomly distributed throughout the left wing membranes. Four masses were removed and diagnosed microscopically as basosquamous carcinomas and papillomas. Additional masses, removed 6 mo and 1 yr later, showed bony invasion and squamous differentiation. Immunohistochemistry detected positive intranuclear staining for bovine papillomavirus antibody in all samples. Polymerase chain reaction done on DNA extracts from formalin-fixed, paraffin-embedded tumor tissue amplified a 450 base-pair segment analogous to the L1 region of human papillomavirus types 96 and 5. Basic Local Alignment Search Tool analysis of sequenced amplicons suggests a novel chiropteran papillomavirus. To our knowledge, this is the first report of papillomavirus-associated carcinoma in a chiropteran species. 相似文献
12.
13.
14.
15.
16.
17.
18.
Managing small remnants of native forest to increase biodiversity within plantation landscapes in the south west of Western Australia 总被引:1,自引:0,他引:1
Robert D. Archibald Michael D. Craig Katarzyna Bialkowski Chris Howe Treena I. Burgess Giles E.St.J. Hardy 《Forest Ecology and Management》2011,261(7):1254-1264
Recent expansion of industrial-scale plantations into agricultural areas in Australia has the potential to assist biodiversity conservation by rehabilitating ecosystems at the landscape scale and reducing edge effects, isolation and disturbance within remnants of native vegetation. However, the efficient management of remnants for biodiversity within a plantation estate requires knowledge of both the causes and the consequences of remnant degradation. With this in mind, we examined key ecosystem features and processes relating to soil chemistry, decomposition, native tree health and regeneration and vertebrate abundance, within small forest remnants (1-4 ha) embedded within Eucalyptus globulus plantations in south west Western Australia. Soil nutrient enrichment was significantly associated with a scale of vegetation modification in order from: (1) intact forest, (2) remnants with native understorey (UDN), (3) remnants with exotic understorey (UDE), (4) plantation and (5) pasture. We propose that, in this region, UDE remnants will often remain in a degraded state even after plantation establishment and the cessation of stock grazing. This is due, in part, to more rapid rates of nutrient turnover sustaining higher nutrient availability in the soil following the replacement of ligneous understorey plants with annual ones. Cotton strips placed in surface soils were often disintegrated in UDE remnants and largely intact in UDN remnants, indicating that decomposition was accelerated in the former. Continued tree decline and regeneration failure within UDE remnants will also reinforce the UDE condition. There was less canopy seed set and little or no seedling establishment in UDE remnants compared to UDN remnants. Therefore, management interventions to assist native tree regeneration in UDE remnants are needed. Fauna trapping highlighted the desirability of retaining, and preferably restoring, small remnants in plantations. Small native mammals were found exclusively in remnants and fewer introduced Mus musculus were present in UDN remnants. Higher numbers of native lizards were found in UDN remnants, but this result was not significant (marginally). 相似文献
19.
Coleman JN Lotya M O'Neill A Bergin SD King PJ Khan U Young K Gaucher A De S Smith RJ Shvets IV Arora SK Stanton G Kim HY Lee K Kim GT Duesberg GS Hallam T Boland JJ Wang JJ Donegan JF Grunlan JC Moriarty G Shmeliov A Nicholls RJ Perkins JM Grieveson EM Theuwissen K McComb DW Nellist PD Nicolosi V 《Science (New York, N.Y.)》2011,331(6017):568-571
If they could be easily exfoliated, layered materials would become a diverse source of two-dimensional crystals whose properties would be useful in applications ranging from electronics to energy storage. We show that layered compounds such as MoS(2), WS(2), MoSe(2), MoTe(2), TaSe(2), NbSe(2), NiTe(2), BN, and Bi(2)Te(3) can be efficiently dispersed in common solvents and can be deposited as individual flakes or formed into films. Electron microscopy strongly suggests that the material is exfoliated into individual layers. By blending this material with suspensions of other nanomaterials or polymer solutions, we can prepare hybrid dispersions or composites, which can be cast into films. We show that WS(2) and MoS(2) effectively reinforce polymers, whereas WS(2)/carbon nanotube hybrid films have high conductivity, leading to promising thermoelectric properties. 相似文献
20.
Nutmeg dispersal by tropical birds 总被引:1,自引:0,他引:1
Frugivorous birds preferentially remove fruits from Panamanian Virola trees where the ratio of edible aril to indigestible seed is high. A negative correlation between the proportion of the crop removed and mean seed size explains 59 percent of the variance in removal, suggesting that birds minimize ingestion of useless bulk. 相似文献