全文获取类型
收费全文 | 6384篇 |
免费 | 356篇 |
国内免费 | 295篇 |
专业分类
林业 | 1208篇 |
农学 | 458篇 |
基础科学 | 64篇 |
529篇 | |
综合类 | 2763篇 |
农作物 | 293篇 |
水产渔业 | 89篇 |
畜牧兽医 | 421篇 |
园艺 | 316篇 |
植物保护 | 894篇 |
出版年
2024年 | 37篇 |
2023年 | 98篇 |
2022年 | 135篇 |
2021年 | 149篇 |
2020年 | 185篇 |
2019年 | 198篇 |
2018年 | 112篇 |
2017年 | 202篇 |
2016年 | 282篇 |
2015年 | 253篇 |
2014年 | 310篇 |
2013年 | 382篇 |
2012年 | 518篇 |
2011年 | 505篇 |
2010年 | 433篇 |
2009年 | 450篇 |
2008年 | 363篇 |
2007年 | 387篇 |
2006年 | 329篇 |
2005年 | 252篇 |
2004年 | 206篇 |
2003年 | 164篇 |
2002年 | 135篇 |
2001年 | 92篇 |
2000年 | 109篇 |
1999年 | 108篇 |
1998年 | 93篇 |
1997年 | 73篇 |
1996年 | 93篇 |
1995年 | 56篇 |
1994年 | 59篇 |
1993年 | 55篇 |
1992年 | 33篇 |
1991年 | 34篇 |
1990年 | 32篇 |
1989年 | 31篇 |
1988年 | 18篇 |
1987年 | 21篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1955年 | 6篇 |
排序方式: 共有7035条查询结果,搜索用时 15 毫秒
1.
Resistance to Leveillula taurica in the genus Capsicum 总被引:1,自引:0,他引:1
One hundred and sixty-two Capsicum genotypes were evaluated for powdery mildew (Leveillula taurica) resistance, following inoculations with a suspension of 5 × 104 conidia mL−1 on 10-leaved to 12-leaved plants. Genotypes were graded into five resistance classes, based on the areas under the disease progress curves calculated from disease incidence (percentage infected leaves per plant) and severity (total number of colonies per plant). Results revealed a continuum from resistance to susceptibility, with the majority (70%) of C. annuum materials being classified as moderately to highly susceptible to L. taurica. Conversely, C. baccatum, C. chinense and C. frutescens were most often resistant, indicating that resistance to L. taurica among Capsicum species is found mainly outside the C. annuum taxon. Nevertheless, some resistant C. annuum material was identified that may be useful for resistance breeding. Eight genotypes were identified as immune to the pathogen: H-V-12 and 4638 (previously reported), and CNPH 36, 38, 50, 52, 279 and 288. Only H-V-12 and 4638 are C. annuum, while all others belong to the C. baccatum taxon. Latent period of disease on a set of commercial sweet pepper genotypes varied, indicating diverse levels of polygenic resistance. The latent period progressively reduced with plant maturity, from 14·3 days in plants at the mid-vegetative stage to 8·6 days in plants at the fruiting stage. Young plants of all commercial genotypes tested at the early vegetative stage were immune, irrespective of the reaction of the genotype at later stages, demonstrating widespread juvenile resistance to L. taurica in the Capsicum germplasm. Inoculation of plants of different botanical taxa with a local isolate indicated a wide host range. Some hosts, including tomato (Lycopersicon esculentum), artichoke (Cynara scolymus) and poinsettia (Euphorbia pulcherrima), produced large amounts of secondary inoculum. Other hosts included okra (Abelmoschus esculentus), eggplant (Solanum melongena), cucumber (Cucumis sativus), Solanum gilo, Chenopodium ambrosioides and Nicandra physaloides. 相似文献
2.
嘉兴城区公园木本观赏植物调查研究 总被引:1,自引:0,他引:1
对嘉兴市城区10个公园的绿地木本观赏植物的种类、生长状况、景观配置等调查结果显示:共有观赏树木157种,乔木∶灌木∶藤本比例为82∶64∶11,落叶树种与常绿树种之比为86∶71,各树种生长良好,但存在养护管理技术跟不上,树种配置时对立地条件考虑不充分等问题。 相似文献
3.
不同寄主来源的葡萄霜霉病菌致病力测定及孢子囊大小比较 总被引:2,自引:0,他引:2
对采自我国不同地区、不同主栽葡萄品种‘红地球’、‘巨峰’及‘赤霞珠’上的12份葡萄霜霉病菌的致病力及孢子囊大小进行了比较和分析,结果表明:采自不同葡萄品种的病原菌对感病葡萄品种‘奥迪亚无核’叶片的致病力具有明显差异,其中‘巨峰’及‘红地球’来源的病原菌致病性较强,明显大于‘赤霞珠’来源的病原菌致病力;采自不同葡萄品种的霜霉病菌孢子囊大小存在一定的差异,‘赤霞珠’来源的病原菌孢子囊明显大于‘巨峰’及‘红地球’来源的霜霉病菌孢子囊。上述结果表明,采自不同寄主的葡萄霜霉病菌的致病力及孢子囊大小均存在一定程度的分化。 相似文献
4.
在用棉花、大豆、花生功能叶饲养棉铃虫幼虫的基础上,测定各寄主功能叶的营养成分、木质素和纤维素含量,研究棉铃虫在取食不同寄主叶片后的生物学和营养效应。结果表明:1、取食棉花叶的生物学效应较好,取食花生叶的幼虫成活率下降,取食大豆叶的幼虫体重偏轻;2、取食棉花叶的营养效应较好,大豆叶最次;3、棉铃虫幼虫的食物转化率和食物利用率以棉花叶最高,棉铃虫嗜食棉花叶,在3种作物田同时存在的情况下,棉田被害最重。 相似文献
5.
Oded Cohen Ozgur Batuman Yoni Moskowits Alexander Rozov Elisha Gootwine Munir Mawassi Moshe Bar-Joseph 《Phytoparasitica》2005,33(2):141-148
Mechanical inoculations with contaminating tools and propagation of infected budwood were considered the main causes for the
omnipresence of multiple viroid species among citrus and other Middle Eastern and Mediterranean fruit trees and grapevines.
However, neither means could explain viroid infections of wild trees — scattered on terrains inaccessible to humans — nor
the finding of similar viroids among graft-incompatible plants. Northern hybridization of RNA extracts made of scrapings from
the surfaces of goat (Capra hircus) horns that were rubbed against etrog (Citrus medica) stems infected with a citrus viroids complex, revealed accumulation of considerable amounts ofCitrus exocortis viroids (CEVd) andHop stunt viroids (HSVd). Experimental transmission of both CEVd and HSVd was obtained by rubbing healthy citrus plants with goat horns that
had been rubbed 24 h earlier on infected etrog stems. These results implicate goats as possible vectors of viroids. Transmissionvia goats could have facilitated the long-range spread of viroids among cultivated and wild plants andvice versa and also among graft-incompatible plants. 相似文献
6.
7.
8.
在室内研究了豌豆潜蝇姬小蜂对4种寄主植物上美洲斑潜蝇2龄末-3龄初幼虫的选择性和寄生蜂子代生长发育及存活情况。结果表明,豌豆潜蝇姬小蜂雌蜂对不同寄主植物具有选择性差异,对菜豆选择性最强,对番茄选择性最低,斑潜蝇被致死率和被寄生率分别为96.1%、71.4%和73.4%、52.1%;在4种寄主植物上,寄生蜂对寄主的寄生数与致死数比值无显著差异。寄生不同寄主植物上斑潜蝇幼虫的豌豆潜蝇姬小蜂从卵发育到成虫的历期存在差异,在黄瓜上历期最长,为10.21d;寄生蜂蛹期稍短于卵期与幼虫期之和;但寄生不同寄主植物上斑潜蝇幼虫的寄生蜂卵孵化率、幼虫存活率、羽化率无显著差异。 相似文献
9.
Karel?PetrzikEmail author 《European journal of plant pathology / European Foundation for Plant Pathology》2005,111(4):355-360
Apple mosaic virus (ApMV, genus Ilarvirus) was detected in pears, a previously non-reported virus host. No symptoms were visible on the hosts leaves. Seventeen out of 22 randomly selected pear trees in Italy (Lombardy) and in three regions in the Czech Republic were ApMV-infected. All nine newly sequenced ApMV isolates from pears had a 15-nucleotide insertion in the capsid protein gene in identical position of that of apple isolates compared with isolates from hop and prunes. The insertion is the most prominent (but not essential) modification of the capsid protein gene, which results in a phylogenetic separation of ApMV isolates into three clusters. Sequence analysis data of an additional 15 isolates revealed a sequence correlation with kernelled fruit trees (apple and pear). 相似文献
10.
A. P. Sclavounos A. E. Voloudakis Ch. Arabatzis P. E. Kyriakopoulou 《European journal of plant pathology / European Foundation for Plant Pathology》2006,115(2):163-172
A severe strain of Cucumber mosaic virus (CMV) originating from an infected tomato plant (Gastouni-Olympia, Greece) was isolated in tobacco (Nicotiana tabacum cv. Xanthi nc), after three serial local lesion passages in Chenopodium quinoa and designated CMV-G. CMV-G induces yellow mosaic (YM) symptoms in tobacco. When CMV-G was passed mechanically through C. quinoa, phenotypic variants inducing YM or green mild mosaic (MM) in tobacco were isolated. Aphid transmission, from different hosts, appears to be an effective approach for separating MM variants of CMV-G from YM variants. In particular, aphid transmission from zucchini proved to be very efficient in selecting for MM variants. In contrast, aphids transmitted only YM variants from tomato plants. Molecular characterization of CMV-G and its progeny resulted in their classification in the CMV subgroup IB, free of satellite RNA, being the first discovery of the subgroup IB in Greece. In the Solanaceae family (tobacco, tomato, pepper) YM variants induced more severe symptoms than the MM variants. YM and MM phenotype was stable in tobacco for all seven passages tried using the obtained YM and MM variants. Cross-protection experiments showed that an isolated MM variant was able to protect tobacco plants against a challenge infection by a YM variant. 相似文献