全文获取类型
收费全文 | 1194篇 |
免费 | 71篇 |
国内免费 | 16篇 |
专业分类
林业 | 140篇 |
农学 | 48篇 |
基础科学 | 9篇 |
216篇 | |
综合类 | 138篇 |
农作物 | 50篇 |
水产渔业 | 80篇 |
畜牧兽医 | 423篇 |
园艺 | 40篇 |
植物保护 | 137篇 |
出版年
2023年 | 11篇 |
2022年 | 25篇 |
2021年 | 31篇 |
2020年 | 39篇 |
2019年 | 24篇 |
2018年 | 42篇 |
2017年 | 66篇 |
2016年 | 52篇 |
2015年 | 33篇 |
2014年 | 50篇 |
2013年 | 62篇 |
2012年 | 81篇 |
2011年 | 83篇 |
2010年 | 65篇 |
2009年 | 62篇 |
2008年 | 70篇 |
2007年 | 65篇 |
2006年 | 60篇 |
2005年 | 51篇 |
2004年 | 43篇 |
2003年 | 33篇 |
2002年 | 36篇 |
2001年 | 18篇 |
2000年 | 13篇 |
1999年 | 10篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1984年 | 3篇 |
1981年 | 3篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1973年 | 8篇 |
1972年 | 5篇 |
1970年 | 4篇 |
1959年 | 2篇 |
1957年 | 2篇 |
1956年 | 2篇 |
1925年 | 2篇 |
1858年 | 3篇 |
1857年 | 2篇 |
排序方式: 共有1281条查询结果,搜索用时 15 毫秒
1.
2.
Fritz Hervé Saïd Sonia Renaud Pierre-Cyril Mutake Snoden Coid Craig Monicat François 《Landscape Ecology》2003,18(3):293-302
After the eradication of the Tse-Tse fly in the Mid-Zambezi valley, human settlements and fields extended mainly along the main rivers. In order to investigate the consequences of this human development on wildlife diversity we monitored three rivers of the Mid-Zambezi valley in Zimbabwe: Angwa, Manyame and Kadzi. The rivers were divided in segments of 200 m which were checked for spoors in order to assess the number of species and the number of individuals that used the segments. Human settlements were also recorded. We used a GIS to define the spatial characteristics of the fields present along the rivers, and related them to the distribution and abundance of wild species spoors in the river beds and banks. Our results show that the number of species in one segment of the river decreased with the increasing size of the field area bordering the segment. For all the major ungulate species, the numbers of individuals recorded per segment decreased with increasing field area. A similar trend was observed for small and medium-sized carnivores, though they were in lower numbers when present. Our analyses thus confirm that the extension of human agriculture in wildlife areas has an impact on most wild species, but we also define some threshold value of field size above which there seem to be an acceleration of the decrease in wildlife density and diversity: 3.2 ha for medium and small herbivores and carnivores; only the elephant seem to tolerate larger field area with a threshold value of 32 ha.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
3.
4.
Alan Mario Zuffo Fábio Steiner Tiago de Oliveira Sousa Jorge González Aguilera Paulo Eduardo Teodoro Francisco de Alcântara Neto Rafael Felippe Ratke 《Journal of Agronomy and Crop Science》2020,206(6):837-850
The effects of water and salt stress on rate of germination and seedling growth were investigated under laboratory conditions in 46 soya bean genotypes from Central-West region of Brazil to verify how these stresses may limit crop establishment during the initial growth stage and also to identify the most tolerant genotypes to drought and salinity. Mild water and salt stresses were imposed by seed exposure to –0.20 MPa iso-osmotic solutions with polyethylene glycol—PEG 6000 (119.57 g/L) or NaCl (2.357 g/L) for 12 days at 25°C. The germination percentage, seedling length and seedling dry matter were measured, and then, salt or drought tolerance indexes were calculated. The “NS 5909 RG,” “NS 7000 IPRO,” “NS 7338IPRO,” “FPS Solimões RR,” “NS 5151 IPRO,” “SYN 13610 IPRO,” “LG 60177 IPRO,” “NS 6909 IPRO” and “BMX Desafio RR” were identified as the most drought-tolerant genotypes, whereas under salinity conditions, the genotypes “5D 615 RR,” “BMX Desafio RR,” “5D 6215 IPRO” and “BMX Ponta IPRO” were identified as tolerant. The “BMX Desafio RR” is the genotype most adapted to both stress conditions and, therefore, should be used under conditions of water shortage and excess salt in the soil at sowing time. 相似文献
5.
Composition and fatty acid profile of milk from cows supplemented with pressed oilseed cake
下载免费PDF全文
![点击此处可从《Animal Science Journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ronaldo Lopes Oliveira Severino Gonzaga Neto Francisco Helton Sa de Lima Ariosvaldo Nunes de Medeiros Leilson Rocha Bezerra Elzania Sales Pereira Adriana Regina Bagaldo Caius Barcellos de Pellegrini Braulio Rocha Correia 《Animal Science Journal》2016,87(10):1225-1232
This study compared the productive and nutritional parameters of milk from crossbred lactating cows managed on Panicum maximum Jacq. cv. Tanzania and with a diet supplemented with different pressed oilseed cakes. The supplements used were as follows: peanut cake, sunflower cake and palm kernel cake for replacement of soybean meal. Sixteen cows with an average weight of 544 ± 57 kg and producing 8 ± 1.4 L of milk per day were used in this study. The animals were randomly assigned to the treatments according to a Latin square design repeated over time, with four treatments, 16 animals and four experimental periods. Supplementation of the diet with peanut cake, sunflower cake and palm kernel cake compared with soybean meal in the diet of cows did not affect the average daily production or composition of the milk. The palm kernel cake promoted an increase in lauric fatty acids (C12:0) and palmitoleic acids (C16:1) (5.02 and 1.65%, respectively) compared with peanut cake and sunflower cake (4.13 and 4.01%, respectively). The levels of oleic fatty acids (C18:1) were higher for the sunflower cake and palm kernel cake supplements (26.01 and 25.01%, respectively) compared with peanut cake (23.11%). The replacement of soybean meal with sunflower cake and palm kernel cake improved the nutritional quality of the milk, with lower concentrations of saturated fatty acids and higher concentrations of unsaturated fatty acids, without compromising the production or nutritional composition of the milk. © 2015 Japanese Society of Animal Science 相似文献
6.
In Tunisia both Psammomys obesus and P. vexillaris are found. These taxa have been the subject of taxonomic controversy for some time, due to variability in the classical morphological characters used for taxonomic recognition. In this study we investigated skull size and shape variation in the genus Psammomys by using geometric morphometrics to evaluate the extent of intra- and interspecific shape variation and explicitly tested for the impact of allometric shape variation on species discrimination. Eleven populations of the two species from 10 localities in Tunisia were studied. Statistical analyses of size and shape showed large size variation within P. obesus, but no shape differences were revealed among populations of this species. Interspecific analysis revealed that P. vexillaris had the smallest skull. Principal component analysis and Procrustes distances showed good discrimination between the two species after removal of the allometric component of shape variation. The results obtained show that allometric-related shape variation could mask discrimination between the two Psammomys species. This finding might explain the uncertainty in classification of these species in the past. The interspecific allometric-free phenotypic differences observed may be associated with adaptive processes linked to the different environmental and trophic preferences of the two species. 相似文献
7.
Comparison of 4 point‐of‐care blood gas analyzers for arterial blood gas analysis in healthy dogs and dogs with cardiopulmonary disease
下载免费PDF全文
![点击此处可从《Journal of Veterinary Emergency and Critical Care》网站下载免费的PDF全文](/ch/ext_images/free.gif)
8.
9.
10.
Aguiar PH Barrouin-Melo SM Franke CR dos Santos RR Silva TM Mengel JO dos-Santos WL Pontes-de-Carvalho L 《Veterinary journal (London, England : 1997)》2007,173(1):158-166
This report describes the characterisation of a monoclonal antibody (mAb), AB6, which recognises specifically a cluster of canine leukocyte surface molecules. The immunogen used for obtaining the AB6 mAb was a lysate of canine peripheral blood mononuclear cells (PBMC). This novel mAb belongs to the IgG2a isotype, and reacted in Western blot with four different canine leukocyte glycoproteins with apparent molecular weights of 180, 190, 205 and 220 kDa. The AB6 mAb recognised the majority of canine peripheral blood leukocytes as determined by flow cytometry (97%). It also exhibited a broad reactivity pattern against lymphoid and myeloid cells, inhibited the proliferation of mitogen-stimulated canine PBMC and did not recognise human PBMC and murine splenocytes. The biochemical properties, cell and tissue specificity, and in vitro biological activity of the AB6 mAb indicate that it recognises a canine CD45 homologue. The mAb could become a valuable diagnostic and research tool for the evaluation of immune functions in dogs. 相似文献