全文获取类型
收费全文 | 1046篇 |
免费 | 36篇 |
国内免费 | 83篇 |
出版年
2023年 | 6篇 |
2022年 | 19篇 |
2021年 | 25篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 10篇 |
2017年 | 11篇 |
2016年 | 17篇 |
2015年 | 24篇 |
2014年 | 44篇 |
2013年 | 53篇 |
2012年 | 40篇 |
2011年 | 36篇 |
2010年 | 18篇 |
2009年 | 46篇 |
2008年 | 63篇 |
2007年 | 53篇 |
2006年 | 68篇 |
2005年 | 55篇 |
2004年 | 45篇 |
2003年 | 43篇 |
2002年 | 25篇 |
2001年 | 35篇 |
2000年 | 23篇 |
1999年 | 33篇 |
1998年 | 25篇 |
1997年 | 20篇 |
1996年 | 30篇 |
1995年 | 43篇 |
1994年 | 28篇 |
1993年 | 21篇 |
1992年 | 11篇 |
1991年 | 23篇 |
1990年 | 28篇 |
1989年 | 13篇 |
1988年 | 14篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1971年 | 1篇 |
1970年 | 3篇 |
排序方式: 共有1165条查询结果,搜索用时 15 毫秒
71.
The inhibition of 2,4-D-induced elongation growth by galactoglucomannan oligosaccharides (GGMOs) in pea stem segments (Pisum sativum L. cv. Tyrkys) after 18 h of incubation results in changes of extracellular, intracellular and cell wall glycosidase activities (beta-D-glucosidase, beta-D-mannosidase, beta-D-galactosidase, beta-D-xylosidase, alpha-D-galactosidase, and alpha-L-arabinosidase). GGMOs lowered the glycosidase activities in the extracellular fraction, while in the cell wall fractions their activities were markedly increased. The intracellular enzyme alpha-d-galactosidase increased while the beta-d-galactosidase decreased in activity in response to the GGMO treatment. Extracellular enzymes showed low values of activities in comparison with intracellular and cell wall glycosidases. It is evident that GGMOs can alter auxin induced elongation and glycosidase activities in different compartments of the cell, however, the mode and site of their action remains unclear. 相似文献
72.
Cui?Yu Dongwei?Hu Jiahong?Dong Xiaofeng?Cui Junjie?Wu Jialin?Yu Xueping?ZhouEmail author 《中国科学C辑(英文版)》2004,47(6):503-509
Tobacco mosaic virus (TMV) and Tomato mosaic virus (ToMV) are two closely related viruses in the genus Tobamovirus, but they induce obviously different sizes of necrotic lesions in tobacco plants containing the N gene. Comparison of the symptoms produced by TMV, ToMV and a chimaeric virus (T/OMP), in which the TMV movement protein (MP)
gene was replaced by the ToMV MP gene, showed T/OMP caused necrotic lesions that were similar in size to those of ToMV in tobacco plants containing the N gene. The coat protein and MP of the three viruses accumulated in planta with similar levels, and the replication level of TMV and T/OMP in protoplasts also had no difference. Comparison of the
activities of defense-related enzymes (PAL, POD and PPO) induced by the three viruses also showed that the variability of
enzyme activity induced by T/OMP was similar to that induced by TMV, but different from that induced by ToMV. The results
indicate that the size difference of necrotic lesions induced by TMV and ToMV in tobacco plants containing the N gene results from the functional difference of their MP genes. 相似文献
73.
Coordinate induction of glutathione biosynthesis and glutathione-metabolizing enzymes is correlated with salt tolerance in tomato 总被引:2,自引:0,他引:2
Mittova V Theodoulou FL Kiddle G Gómez L Volokita M Tal M Foyer CH Guy M 《FEBS letters》2003,554(3):417-421
The acclimation of reduced glutathione (GSH) biosynthesis and GSH-utilizing enzymes to salt stress was studied in two tomato species that differ in stress tolerance. Salt increased GSH content and GSH:GSSG (oxidized glutathione) ratio in oxidative stress-tolerant Lycopersicon pennellii (Lpa) but not in Lycopersicon esculentum (Lem). These changes were associated with salt-induced upregulation of gamma-glutamylcysteine synthetase protein, an effect which was prevented by preincubation with buthionine sulfoximine. Salt treatment induced glutathione peroxidase and glutathione-S-transferase but not glutathione reductase activities in Lpa. These results suggest a mechanism of coordinate upregulation of synthesis and metabolism of GSH in Lpa, that is absent from Lem. 相似文献
74.
Expression in Nicotiana tabaccum L. plants containing the -glucuronidase (GUS) gene under the control of the 35S (CaMV promoter) was affected by tissue type and ontogenic development of the leaves. GUS activity in ontogenetically younger leaves was 1003–1022 nmol 7-hydroxy-4-methylcoumarin (MU) formed mg–1 (protein) min–1 and in ontogenetically older leaves was only 140–198 nmol (MU) mg–1 (protein) min–1. 相似文献
75.
In glasshouse tests, sap from plants infected with 15 different isolates of tomato spotted wilt tospovirus (TSWV) from three Australian states was inoculated to nine genotypes of tomato carrying TSWV resistance gene Sw-5 or one of its alleles. A further two resistant tomato genotypes were inoculated with four isolates each. The normal response in resistant genotypes was development of necrotic local lesions in inoculated leaves without systemic invasion, but 22/752 plants also developed systemic reactions in addition to local hypersensitive ones. Using cultures from two of these systemically infected plants and following four cycles of subculture in TSWV resistant tomato plants, two isolates were obtained that gave susceptible type systemic reactions but no necrotic spots in inoculated leaves of resistant tomatoes. When these two isolates, DaWA-1d and ToTAS-1d, were maintained by repeated subculture for 10 successive cycles in Nicotiana glutinosa or a susceptible tomato genotype, they still induced susceptible type systemic reactions when inoculated to resistant tomato plants. They were therefore stable resistance breaking isolates as regards overcoming gene Sw-5. When resistance-breaking isolate DaWA-1ld multiplied together with original isolate DaWA-l in susceptible tomato, it was fully competitive with the original isolate. However, when DaWA-ld and ToTAS-ld were inoculated to TSWV resistant Lycopersicon peruvianum lines PI 128660R and PI 128660S and to TSWV resistant Capsicum chinense lines PI 152225, PI 159236 and AVRDC CO0943, they failed to overcome the resistance, producing only necrotic local lesions without systemic infection. Thus, although the ease of selection, stability and competitive ability of resistance breaking isolates of TSWV is cause for concern, L. peruvianum and C. chinense lines are available which are effective against them. The effectiveness of the resistance to TSWV in nine tomato genotypes was examined in a field experiment. Spread was substantial in the susceptible control genotype infecting 42% of plants. Resistance was ineffective in cv. Bronze Rebel, 26% of plants developing infection. In contrast, it held up well in the other eight resistant genotypes with only 1–3 or no plants of each becoming infected. Accumulated numbers of Thrips tabaci, Frankliniella occidentalis and F. schultzei were closely correlated with TSWV spread. 相似文献
76.
番茄抗病基因Cf9的3′UTR区含有内含子序列 总被引:2,自引:0,他引:2
从番茄(LycopersiconesculentumMil.)抗病品种“中杂9号”基因组DNA中扩增并克隆了番茄抗叶霉病基因Cf9。序列分析结果表明,该基因全长2751bp,含有一个编码863个氨基酸的开放阅读框架。在该基因的3′UTR区发现了一段未曾报道的内含子序列,长115bp,它所处的位置与番茄另一个抗叶霉病基因Cf2内含子的位置相似,其5′和3′边界序列为一重复序列,TCCAGG(T)ATTC,并与Cf2基因内含子边界序列高度同源。与已报道的Cf9的cDNA序列相比,它的第371位的核苷酸T突变成了C,从而使其编码蛋白的LRR区第121位的亮氨酸突变为脯氨酸。 相似文献
77.
M. M. M. Miranda M. Pican o J. C. Zanuncio R. N. c. Guedes 《Biocontrol Science and Technology》1998,8(4):597-606
An ecological life table was constructed, aiming to determine the critical stages and key mortality factors of Tuta absoluta (Lepidoptera: Gelechiidae). The total population mortality of this tomato leafminer was 92.3%. During the egg stage the mortality was 58.7%, mainly due to egg inviability. A total of 8.6% egg parasitism by Trichogramma pretiosum (Riley) (Hymenoptera: Trichogrammatidae) and 5.0% egg predation by Xylocoris sp. (Heteroptera: Anthocoridae), Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae) and members of the family Phlaeothripidae (Thysanoptera) was observed. The mortality of the larval stage was 33.0%. This was considered to be the critical stage as it showed the highest apparent mortality (79.8%). Larval parasitism was low (0.1%), and was only found with Goniozus nigrifemur Ashmead (Hymenoptera: Bethylidae). Predators were responsible for 79.4% of larval mortality. Therefore, their attraction to and maintenance in the target area are important management tactics to be considered for T. absoluta control. The first and second instars were considered to be the most critical, and predation by the above mentioned species was the key mortality factor. The mortality at the pupal stage was low (0.6%) and was due to malformation. 相似文献
78.
79.
Henryk Pospieszny Marta Budziszewska Beata Hasiów‐Jaroszewska Aleksandra Obrępalska‐Stęplowska Natasza Borodynko 《Journal of Phytopathology》2010,158(1):56-62
Three isolates of Tomato torrado virus (ToTV) were found in Poland. The isolates were characterized on the basis of their symptomatology on plant species, serological reactions, electron microscopy, and nucleotide and amino acid sequence analyses of coat protein subunit genes. In comparative tests, the Polish ToTV isolates were shown to be closely related to each other and also to the isolate from Spain. 相似文献
80.
Maurice O. Ouko Adrian Sambade Katrin Brandner Annette Niehl Eduardo Peña Abdul Ahad Manfred Heinlein Peter Nick 《The Plant journal : for cell and molecular biology》2010,62(5):829-839
A panel of seven SR1 tobacco mutants (ATER1 to ATER7) derived via T‐DNA activation tagging and screening for resistance to a microtubule assembly inhibitor, ethyl phenyl carbamate, were used to study the role of microtubules during infection and spread of tobacco mosaic virus (TMV). In one of these lines, ATER2, α‐tubulin is shifted from the tyrosinylated into the detyrosinated form, and the microtubule plus‐end marker GFP–EB1 moves significantly slower when expressed in the background of the ATER2 mutant as compared with the SR1 wild type. The efficiency of cell‐to‐cell movement of TMV encoding GFP‐tagged movement protein (MP‐GFP) is reduced in ATER2 accompanied by a reduced association of MP‐GFP with plasmodesmata. This mutant is also more tolerant to viral infection as compared with the SR1 wild type, implying that reduced microtubule dynamics confer a comparative advantage in face of TMV infection. 相似文献