全文获取类型
收费全文 | 13736篇 |
免费 | 1048篇 |
国内免费 | 3篇 |
专业分类
林业 | 1177篇 |
农学 | 535篇 |
基础科学 | 113篇 |
3592篇 | |
综合类 | 440篇 |
农作物 | 674篇 |
水产渔业 | 1391篇 |
畜牧兽医 | 5439篇 |
园艺 | 232篇 |
植物保护 | 1194篇 |
出版年
2023年 | 105篇 |
2022年 | 157篇 |
2021年 | 341篇 |
2020年 | 321篇 |
2019年 | 262篇 |
2018年 | 649篇 |
2017年 | 659篇 |
2016年 | 657篇 |
2015年 | 514篇 |
2014年 | 608篇 |
2013年 | 933篇 |
2012年 | 1057篇 |
2011年 | 990篇 |
2010年 | 562篇 |
2009年 | 489篇 |
2008年 | 786篇 |
2007年 | 785篇 |
2006年 | 638篇 |
2005年 | 612篇 |
2004年 | 543篇 |
2003年 | 511篇 |
2002年 | 417篇 |
2001年 | 296篇 |
2000年 | 305篇 |
1999年 | 261篇 |
1998年 | 64篇 |
1997年 | 52篇 |
1996年 | 41篇 |
1995年 | 31篇 |
1994年 | 31篇 |
1993年 | 31篇 |
1992年 | 75篇 |
1991年 | 63篇 |
1990年 | 63篇 |
1989年 | 85篇 |
1988年 | 49篇 |
1987年 | 70篇 |
1986年 | 58篇 |
1985年 | 63篇 |
1984年 | 48篇 |
1983年 | 48篇 |
1982年 | 26篇 |
1981年 | 27篇 |
1979年 | 39篇 |
1978年 | 33篇 |
1977年 | 34篇 |
1974年 | 30篇 |
1973年 | 52篇 |
1972年 | 38篇 |
1971年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
2.
Pedro A. Castrillo Catuxa Varela-Dopico Paz Ondina María Isabel Quiroga Roberto Bermúdez 《Journal of fish diseases》2020,43(1):69-80
Freshwater mussels of the order Unionida encyst into the fish mucosa to metamorphose and complete their life cycle, causing a parasitic disease known as glochidiosis. This parasitic stage represents a bottleneck for the survival of naiads, particularly for critically endangered species as Margaritifera margaritifera; however, little is known about the events occurring during this critical stage. Therefore, this study aimed to histologically characterize the development of M. margaritifera glochidiosis in Atlantic salmon to get insight into the pathogenesis of this interaction. Fish exposed to glochidia were sampled during the first 44 days post-exposure, and organs were observed by stereomicroscopy and light microscopy. Glochidia attached to the gills by pinching the lamellar epithelium, whereupon an acute proliferative branchitis engulfed most of the larvae. However, during the first 14 days, a severe detachment of unviable glochidia occurred, associated with the presence of pleomorphic inflammatory infiltrate and epithelial degeneration. In the cases where larvae remained attached, a chronification of the lesions with none to scarce inflammation was observed. These results provide key information to better understand the complex host–parasite interaction during the early stages of glochidiosis and provide valuable information to optimize artificial rearing of naiads in conservation of threatened freshwater mussel populations. 相似文献
3.
Andrés F. Sánchez-Restrepo Nadia L. Jiménez Viviana A. Confalonieri Luis A. Calcaterra 《国际虫害防治杂志》2019,65(3):244-257
AbstractLeaf-cutting ants (LCA) are considered one of the main herbivores and one of the most destructive pest insects of the Neotropics. Northeastern Argentina harbors the greatest species richness of these ants and in turn comprises the highest surface with forest plantations. Our aim was to establish which species of leaf-cutting ants are most commonly associated with forest plantations by analyzing their geographic distribution using published and unpublished species occurrence data. Also, estimate their potential areas of distribution along a latitudinal gradient that entirely encompasses northeastern Argentina using Ecological Niche Modeling. Only seven of the 20 species recorded were strongly associated with productive systems along the gradient, but only 2–3 species in each region could be considered high-risk species for forest plantations. High-risk species composition shows a turnover between regions. Our models show the potential distribution areas where LCA could become more abundant and dominant, and possibly causing a detrimental effect on the forest plantations in the studied region. We find that ecological niche models are useful tools to assess the environmental suitability of important LCA. 相似文献
4.
5.
Mattana Efisio Peguero Brígido Di Sacco Alice Agramonte Wilvin Encarnación Castillo Wilkin Rafael Jiménez Francisco Clase Teodoro Pritchard Hugh W. Gómez-Barreiro Pablo Castillo-Lorenzo Elena Terrero Encarnación Marianny Way Michael J. García Ricardo Ulian Tiziana 《New Forests》2020,51(4):705-721
New Forests - Native trees from the Caribbean were tested for seed desiccation responses, by adapting the “100-seed test” protocol. Ninety-seven seed lots of 91 species were collected... 相似文献
6.
da Silva Isadora Gonçalves Castoldi Renata de Oliveira Charlo Hamilton César de Souza Miranda Mateus Nunes Thaíssa Dias Cardoso Costa Luciene Lacerda Lemes Ernane Miranda 《Journal of Crop Science and Biotechnology》2020,23(2):191-196
Journal of Crop Science and Biotechnology - The cultivation of sweet corn is expanding in Brazil, but there are serious constraints about the availability of commercial cultivars. The selection of... 相似文献
7.
Morlin Carneiro Franciele Angeli Furlani Carlos Eduardo Zerbato Cristiano Candida de Menezes Patricia da Silva Gírio Lucas Augusto Freire de Oliveira Mailson 《Precision Agriculture》2020,21(5):979-1007
Precision Agriculture - Crop monitoring through remote sensing techniques enable greater knowledge of average variability in crop growth. Canopy sensors help provide information on the variability... 相似文献
8.
Luis Daniel Jimnez‐Martínez Dariel Tovar‐Ramírez Carlos Alfonso lvarez‐Gonzlez Emyr Pea‐Marín Susana Camarillo‐Coop Rafael Martínez‐García Elena Palacios‐Mechetnov Rosario Martínez‐Yaez Bartolo Concha‐Frías 《Aquaculture Research》2020,51(7):2629-2640
Five experimental diets containing different lipid sources, fish oil (D1), soybean lecithin (D2), corn oil (D3), canola oil (D4) and olive oil (D5), were evaluated in Atractosteus tropicus larvae for the relative gene expression of the enzymes fatty acid synthase (fas), acetyl‐CoA carboxylase 1 (acc1) and carnitine palmitoyltransferase 1C (cpt1c), in addition to their effects on larval growth, survival and cannibalism during a 30‐day feeding trial. Higher growth and survival were obtained in treatments D1 and D2, and lower performance in diets D3, D4 and D5. The highest levels of expression of fas and acc1 occurred in larvae fed with D1, which contained high amounts of n‐3 long‐chain polyunsaturated fatty acids (LC‐PUFA), mainly DHA and EPA FA are regulators of lipogenesis. The higher cpt1c expression in plant‐based diets is attributed to the fact that these diets are rich in α‐linolenic acid (ALA) and low DHA, EPA and ARA levels that favour ß‐oxidation. In conclusion, the diets with fish oil (D1) and soybean lecithin (D2) were the best treatments for larval growth, survival and cannibalism and thus appear to meet both lipid and energy requirements of A. tropicus larvae, meanwhile the use of vegetable oils influences the expression of intermediary lipogenic genes. 相似文献
9.
F. J. Gómez-Gálvez V. Vega-Macías J. C. Hidalgo-Moya J. J. Hidalgo-Moya D. Rodríguez-Jurado 《Plant pathology》2020,69(2):272-283
The application of disinfectants through drip irrigation could be a feasible practice against verticillium wilt (Verticillium dahliae) of olive. OX-VIRIN (activated peroxide) and OX-AGUA AL25 (quaternary ammonium compounds) are two disinfectants that have shown efficacy against V. dahliae in irrigation water and potential for reducing the disease in young olive plants. In this work, various post-planting application strategies incorporating OX-VIRIN (once a month, or twice a month on alternate or successive weeks) or OX-AGUA AL25 (once a month, or twice a month on alternate weeks) were assessed for their effect on V. dahliae in soil, disease in olive trees, and olive yield, in a 2-year pot-experiment under natural environmental conditions. The disinfectants were injected via metering pumps into a drip irrigation system that irrigated olive trees planted in V. dahliae-inoculated soil. All the application strategies significantly reduced the total inoculum density in soil compared to controls with no disinfectants and noninoculated soil. The microsclerotia density was also significantly reduced in disinfested soils by 73.6–86.8%, depending on the strategy. The symptoms and infection incidence were always lower in treatments subjected to disinfestation. The treatment with OX-AGUA AL25 applied twice a month on alternate weeks most reduced the symptoms (by 53.0%) and colonization index (by 70.8%) with respect to untreated water control. This soil disinfestation also significantly strengthened the symptom remission. Tree growth and production were negatively affected by soil inoculation (reduced by 45.6% and 88.7%, respectively), but not so by disinfectants, which even relieved the reduction in inoculated soils, especially when OX-AGUA AL25 was applied. 相似文献
10.
Manuel Soto-Dávila Danixa Martinez Ricardo Oyarzún Juan P. Pontigo Carolina Vargas-Lagos Francisco J. Morera Julia Saravia Fábio Zanuzzo Luis Vargas-Chacoff 《Journal of fish diseases》2020,43(1):111-127
Pathogen interactions with cultured fish populations are well studied, but their effects on native fishes have not been characterized. In Chile, the disease caused by bacterial species Piscirickettsia salmonis represents one of the main issues and is considered to be one of the important pathogens in the field of aquaculture. They have been found to infect native fish. Therefore, it is necessary to understand the impact of P. salmonis on native species of local commercial value, as well as the potential impact associated with the emergence of antibiotic-resistant strains of P. salmonis. Due to this purpose, the native fish Eleginops maclovinus was used in our study. Fish were randomly distributed in tanks and intraperitoneally inoculated with two strains of P. salmonis. No mortality was recorded during the experiment. Cortisol, glucose and total α-amino acid levels increased in fish injected with AUSTRAL-005 strain compared to sham-injected and LF-89-inoculated fish. Moreover, results showed an increase in the activity of carbohydrates and lipids metabolism in liver; and an increase in the carbohydrates, lipids and total α-amino acid metabolism in muscle after injection with AUSTRAL-005. Our results suggest that P. salmonis modulates the physiology of E. maclovinus and the physiological impact increase in the presence of the antibiotic-resistant strain AUSTRAL-005. 相似文献