全文获取类型
收费全文 | 32851篇 |
免费 | 4591篇 |
国内免费 | 1572篇 |
专业分类
林业 | 2846篇 |
农学 | 2948篇 |
基础科学 | 1244篇 |
6584篇 | |
综合类 | 5456篇 |
农作物 | 1644篇 |
水产渔业 | 3931篇 |
畜牧兽医 | 10418篇 |
园艺 | 804篇 |
植物保护 | 3139篇 |
出版年
2024年 | 98篇 |
2023年 | 315篇 |
2022年 | 709篇 |
2021年 | 1085篇 |
2020年 | 1393篇 |
2019年 | 1833篇 |
2018年 | 1742篇 |
2017年 | 1946篇 |
2016年 | 1831篇 |
2015年 | 1775篇 |
2014年 | 1837篇 |
2013年 | 2270篇 |
2012年 | 2169篇 |
2011年 | 2285篇 |
2010年 | 1886篇 |
2009年 | 1530篇 |
2008年 | 1704篇 |
2007年 | 1499篇 |
2006年 | 1326篇 |
2005年 | 1279篇 |
2004年 | 891篇 |
2003年 | 770篇 |
2002年 | 724篇 |
2001年 | 594篇 |
2000年 | 705篇 |
1999年 | 681篇 |
1998年 | 441篇 |
1997年 | 407篇 |
1996年 | 364篇 |
1995年 | 307篇 |
1994年 | 334篇 |
1993年 | 279篇 |
1992年 | 274篇 |
1991年 | 238篇 |
1990年 | 214篇 |
1989年 | 202篇 |
1988年 | 128篇 |
1987年 | 122篇 |
1986年 | 92篇 |
1985年 | 82篇 |
1984年 | 62篇 |
1983年 | 62篇 |
1982年 | 43篇 |
1981年 | 33篇 |
1980年 | 33篇 |
1979年 | 45篇 |
1978年 | 41篇 |
1977年 | 41篇 |
1973年 | 50篇 |
1972年 | 36篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Detection of the Defoliating Pathotype of Verticillium dahliae in Infected Olive Plants by Nested PCR 总被引:2,自引:0,他引:2
Jesús Mercado-Blanco Dolores Rodríguez-Jurado Encarnación Pérez-Artés Rafael M. Jiménez-Díaz 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(1):1-13
Spread of Verticillium wilt into newly established olive orchards in Andalucía, southern Spain, has caused concern in the olive industry in the region. This spread may result from use of Verticillium dahliae-infected planting material, which can extend distribution of the highly virulent, defoliating (D) pathotype of V. dahliae to new areas. In this study, a molecular diagnostic method for the early in planta detection of D V. dahliae was developed, aimed especially at nursery-produced olive plants. For this purpose, new primers for nested PCR were designed by sequencing a 992-bp RAPD marker of the D pathotype. The use of the specific primers and different nested-PCR protocols allowed the detection of V. dahliae pathotype D DNA in infected root and stem tissues of young olive plants. Detection of the pathogen was effective from the very earliest moments following inoculation of olive plants with a V. dahliae pathotype D conidia suspension as well as in inoculated, though symptomless, plants. 相似文献
92.
Carmen García-Limones Ana Hervs Juan A. Navas-Corts Rafael M. Jimnez-Díaz Manuel Tena 《Physiological and Molecular Plant Pathology》2002,61(6):325
To ascertain if active oxygen species play a role in fusarium wilt of chickpea caused by Fusarium oxysporum f. sp. ciceris, the degree of lipid peroxidation (malondialdehyde formation) and the activity levels of diamine oxidase (DAO), an apoplastic H2O2-forming oxidase, and several antioxidant enzymes, namely ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), guaiacol-dependent peroxidase (GPX) and superoxide dismutase (SOD), were determined spectrophotometrically in roots and stems of ‘WR315’ (resistant) and ‘JG62’ (susceptible) chickpea cultivars inoculated with the highly virulent race 5 of the pathogen. Moreover, APX, CAT, GPX and SOD were also analysed in roots and stems by gel electrophoresis and activity staining; and the protein levels of APX and SOD in roots were determined by Western blotting. In roots, infection by the pathogen increased lipid peroxidation and CAT and SOD activities, although such responses occurred earlier in the incompatible compared with the compatible interactions. APX, GPX and GR activities were also increased in infected roots, but only in the compatible interaction. In stems, infection by the pathogen increased lipid peroxidation and APX, CAT, SOD and GPX activities only in the compatible interaction, and DAO activity only in the incompatible one. In general, electrophoregrams agreed with the activity levels determined spectrophotometrically and did not reveal any differences in isoenzyme patterns between cultivars or between infected and non-infected plants. Further, Western blots revealed an increase in the root protein levels of APX in the compatible interaction and in those of SOD in both compatible and incompatible interactions. In conclusion, whereas enhanced DAO activity in stems, and earlier increases in lipid peroxidation and CAT and SOD activities in roots, can be associated with resistance to fusarium wilt in chickpea, the induction of the latter three parameters in roots and stems along with that of APX, GR (only in roots) and GPX (only in stems) activities are rather more associated with the establishment of the compatible interaction. 相似文献
93.
94.
龙白 3号大白菜为矮桩牛心型一代杂种。亲本P 2 0自交不亲和系由通化×胶二叶 60 Coγ辐射诱变群体中选出 ,亲本 2 36自交弱亲和系以龙白 1号大白菜为试材经连续自交育成。龙白 3号高抗病毒病 ,兼抗霜霉病 ,品质优良 ,净菜率高 ,产量为 4 2 2 3.5~ 5 2 0 0 .8kg·(6 6 7m2 ) -1,较对照品种增产 2 0 %左右。 相似文献
95.
96.
Marlene Cordero Pedro L. Ramos Lester Hernández Ana I. Fernández Ana L. Echemendía Rudy Peral Gloria González Daniel García Surey Valdés Ana Estévez Keren Hernández 《Phytoparasitica》2003,31(5):478-489
The presence of a begomovirus in potato plants with yellow mottle symptoms was determined for the first time in Cuba. The
incidence of typical begomovirus-like symptoms in potato plants in some regions of Havana province (Güira de Melena, San José
de las Lajas, Güines and Boyeros) during the growing seasons from 1992 to 1998 was in general low. However, in some cultivars
belonging to the National Program for Potato Genetic Improvement, the incidence reached 100%. Yield losses, determined in
1992 and 1994, ranged as high as 19% to 56.33% depending on the cultivar. Characterization of the causal agent was done by
light microscopy, host range (graft and mechanical transmission), DNA hybridizations, polymerase chain reaction, and restriction
fragment length polymorphism analysis. Nucleotide sequence of the amplified fragments revealed the presence ofTomato mottle Taino virus. The virus was transmittedvia tubers and has been detected in mixed infections withPotato virus X and withPotato leaf roll virus.
http://www.phytoparasitica.org posting Oct. 20, 2003. The first two authors contributed equally to this work. 相似文献
97.
98.
99.
三种暖季型草坪草在干旱条件下脯氨酸含量和抗氧化酶活性的变化 总被引:47,自引:2,他引:47
测定了土壤干旱条件下矮生狗牙根、沟叶结缕草和地毯草相对含水量和相对电导率的变化。结果表明,矮生狗牙根的耐旱性较强,沟叶结缕草次之,而地毯草对干旱敏感。干旱胁迫下,地毯草积累脯氨酸最多,沟叶结缕草次之,矮生狗牙根最少,草坪草的脯氨酸的积累与耐旱性呈负相关。地毯草超氧化物歧化酶(SOD)活性持续升高,过氧化氢酶(CAT)活性在短暂升高后降低,过氧化物酶(POD)活性降低;矮生狗牙根和沟叶结缕草的SOD活性先升后降,CAT和POD活性则维持较高水平,表明草坪草的耐旱性与抗氧化酶活性有关。 相似文献
100.