全文获取类型
| 收费全文 | 126篇 |
| 免费 | 6篇 |
专业分类
| 林业 | 11篇 |
| 农学 | 4篇 |
| 基础科学 | 1篇 |
| 15篇 | |
| 综合类 | 36篇 |
| 农作物 | 6篇 |
| 水产渔业 | 7篇 |
| 畜牧兽医 | 34篇 |
| 园艺 | 5篇 |
| 植物保护 | 13篇 |
出版年
| 2024年 | 1篇 |
| 2023年 | 1篇 |
| 2022年 | 1篇 |
| 2021年 | 3篇 |
| 2019年 | 2篇 |
| 2018年 | 5篇 |
| 2017年 | 3篇 |
| 2016年 | 4篇 |
| 2015年 | 1篇 |
| 2014年 | 7篇 |
| 2013年 | 7篇 |
| 2012年 | 8篇 |
| 2011年 | 10篇 |
| 2010年 | 5篇 |
| 2008年 | 5篇 |
| 2007年 | 5篇 |
| 2006年 | 8篇 |
| 2005年 | 4篇 |
| 2003年 | 6篇 |
| 2002年 | 4篇 |
| 2000年 | 2篇 |
| 1999年 | 5篇 |
| 1998年 | 2篇 |
| 1997年 | 2篇 |
| 1996年 | 2篇 |
| 1995年 | 3篇 |
| 1993年 | 1篇 |
| 1992年 | 1篇 |
| 1990年 | 1篇 |
| 1989年 | 1篇 |
| 1988年 | 1篇 |
| 1985年 | 1篇 |
| 1984年 | 1篇 |
| 1963年 | 1篇 |
| 1944年 | 2篇 |
| 1943年 | 1篇 |
| 1942年 | 1篇 |
| 1935年 | 1篇 |
| 1932年 | 1篇 |
| 1931年 | 2篇 |
| 1930年 | 2篇 |
| 1929年 | 2篇 |
| 1928年 | 3篇 |
| 1925年 | 1篇 |
| 1924年 | 1篇 |
| 1923年 | 1篇 |
排序方式： 共有132条查询结果，搜索用时 15 毫秒
41.
de la Sancha Noé U. Boyle Sarah A. McIntyre Nancy E. Brooks Daniel M. Yanosky Alberto Cuellar Soto Ericka Mereles Fatima Camino Micaela Stevens Richard D. 《Landscape Ecology》2021,36(10):2997-3012
Landscape Ecology - The Dry Chaco spans more than 87 million hectares across Argentina, Bolivia, and Paraguay. This unique forest system has experienced extensive loss and fragmentation due to... 相似文献
42.
对西南大学图书馆的部分借书未还数据进行统计归类,并且将借书超期不还的原因归为3类,即无意错过归还期限、科研需要长期使用、罚款数目少而故意不还.建立层次分析结构模型,应用迭代法计算出权向量;然后根据权向量找出最可能的借书超期不还的原因;最后根据所得结果为图书馆提出合理的建议. 相似文献
43.
No��mie Gaudio Philippe Balandier Gwena?l Philippe Yann Dumas Fr��d��ric Jean Christian Ginisty 《European Journal of Forest Research》2011,130(1):77-89
Depending on its developmental and morphological characteristics, shrubby or herbaceous understorey vegetation interacts differently with tree seedlings during the regeneration process. In acidic temperate forests, three common understorey plant species??Calluna vulgaris (L.) Hull, Pteridium aquilinum (L.) Kuhn in Kersten, Molinia caerulea (L.) Moench??are known to rapidly colonize forest gaps. Therefore, they often develop at the expense of light-demanding Scots pine (Pinus sylvestris L.) seedlings. An experiment was set up in a nursery in central France to mimic early competition occurring in a newly created gap between Scots pine seedlings and these three common understorey species (young forest-harvested individuals planted at 5 densities from 0 to 57 plants m?2). Pine seedling survival and growth (height, diameter, shoot and root biomass) and a functional trait (leaf mass on an area basis, LMA) were measured for 2 years, and cross-analysed against plant density, plant cover and available light. When understorey plant density increased, pine seedling diameter growth and biomass were negatively affected by all three plant species; height growth only slowed beneath Pteridium. These negative effects were closely linked to competition for light beneath Pteridium and Molinia. The application of the Beer?CLambert law gave an extinction coefficient k that was high for Pteridium, intermediate for Molinia and much lower for Calluna. LMA was confirmed as an effective foliar trait to reflect the degree of stress undergone by pine seedlings. 相似文献
44.
• Introduction
Size-density relationships define the maximum number of stems that even-aged stands of a given species can hold in relation to the mean size of trees. They are used to derive stand density measures and are useful tools used to control tree mortality. 相似文献45.
Jung Soo Kim Hyo Jin An Ki Young Kim Won Young Jeong No Hyung Park Dae Young Lim Dong Hyun Kim 《Fibers and Polymers》2013,14(12):2128-2134
To study the effects of short carbon fiber (SCF) on the properties of the polyolefin elastomers (POEs), we prepared the poly(ethylene-co-1-hexene) (PEH)/SCF composites at different percentages of SCF. We also prepared polyethylene (PE)/SCF composites to compare with PEH/SCF composites. PEH was synthesized by the copolymerization of ethylene and 1-hexene using metallocene catalyst/cocatalyst system. Optimum stirring speed, Al/Zr feeding molar ratio, polymerization time, and polymerization temperature were 700 rpm, 600, 30 min, and 60 °C, respectively. We investigated the morphology of the composites using scanning electron microscopy (SEM) and found that the wettability of SCF in PEH/SCF composites was fairly better than that of SCF in PE/SCF composites. It was observed from mechanical tests that the ultimate tensile strength and tensile modulus of PEH/SCF composites were remarkably enhanced as the SCF content increased, whereas those of PE/SCF composites were a little increased. PEH/SCF composites exhibited lower crystallinity than PE/SCF ones. Thermal stability of the composites was enhanced by the addition of SCF. 相似文献
46.
47.
48.
Aleš Lebeda Barbora Mieslerová Marek Petřivalský Lenka Luhová Martina Špundová Michaela Sedlářová Vladimíra Nožková-Hlaváčková David A. C. Pink 《European journal of plant pathology / European Foundation for Plant Pathology》2014,138(3):569-596
Tomato powdery mildew (Oidium neolycopersici) is one of the most devastating diseases of cultivated tomatoes worldwide. Although the first epidemics were recorded more than 25 years ago many aspects of this host-pathogen interaction are still not well understood. Detailed morphological and molecular studies of the anamorphs confirmed that O. neolycopersici is phylogeneticaly close to Erysiphe aquilegiae var. ranunculi. Host range is rather broad, apart from Solanaceae hosts were found in the families Apocynaceae, Campanulaceae, Crassulaceae, Cistaceae, Cucurbitaceae, Linaceae, Malvaceae, Papaveraceae, Pedialiaceae, Scrophulariaceae, Valerianaceae a Violaceae. Non-host resistance within these families is not based on inhibition of formation of primary haustorium, however, on post-haustorial hypersensitive reponse and another type of non-hypersensitive resistance. Screening of wild Solanum species (previous Lycopersicon spp.) germplasm revealed valuable sources of resistance (S. habrochaites, S. pennellii, S. cheesmaniae, S. chilense, S. peruvianum). The main resistance mechanism was found to be a hypersensitive response (HR), in some cases followed by limited development of the pathogen. However, there is a broad variation in resistance response on the histological and cytological level. Interaction between many wild Solanum spp. and O. neolycopersici is race-specific, at least three races were differentiated. In some interspecific crosses (S. lycopersicum × S. habrochaites) adult plant resistance was observed. Biochemical studies focusing on production of reactive oxygen species (ROS) and peroxidase activity during infection of O. neolycopersici showed that production of ROS and activity of corresponding enzymes is related to activation of defence responses in genotypes of wild Solanum sect. Lycopersicon. The significance of nitric oxide (NO) in O. neolycopersici pathogenesis was supported by experiments with NO donors and scavengers. In moderately resistant genotype S. chmielewskii, treatment by heat stress caused slight deceleration of pathogen development, increased production of jasmonic acid (JA) and abscisic acid (ABA) and increased peroxidase activity in infected plants. The different degree of tomato resistance/susceptibility did not markedly change the rate and extent of photosynthetic response to O. neolycopersici; only minimal impairment of photosynthesis was found in both susceptible and moderately resistant genotypes during the first 9 days after inoculation. The accumulated evidence confirm a crucial role of localised increased production of ROS and reactive nitrogen species (RNS) in response to pathogen penetration into plant tissue and its involvement in the plant resistance responses including the initiation and progression of plant cell death in host wild Solanum species. Crucial points of further research are discussed. 相似文献
49.
50.
