全文获取类型
收费全文 | 160篇 |
免费 | 6篇 |
出版年
2018年 | 1篇 |
2017年 | 3篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 12篇 |
2012年 | 3篇 |
2011年 | 9篇 |
2010年 | 15篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 2篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 6篇 |
1999年 | 1篇 |
1998年 | 5篇 |
1997年 | 10篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1966年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有166条查询结果,搜索用时 15 毫秒
11.
The K+/H+ antiporter LeNHX2 increases salt tolerance by improving K+ homeostasis in transgenic tomato 总被引:1,自引:0,他引:1
RAÚL HUERTAS LOURDES RUBIO OLIVIER CAGNAC MARÍA JESÚS GARCÍA‐SÁNCHEZ JUAN DE DIOS ALCHÉ KEES VENEMA JOSÉ ANTONIO FERNÁNDEZ MARÍA PILAR RODRÍGUEZ‐ROSALES 《Plant, cell & environment》2013,36(12):2135-2149
The endosomal LeNHX2 ion transporter exchanges H+ with K+ and, to lesser extent, Na+. Here, we investigated the response to NaCl supply and K+ deprivation in transgenic tomato (Solanum lycopersicum L.) overexpressing LeNHX2 and show that transformed tomato plants grew better in saline conditions than untransformed controls, whereas in the absence of K+ the opposite was found. Analysis of mineral composition showed a higher K+ content in roots, shoots and xylem sap of transgenic plants and no differences in Na+ content between transgenic and untransformed plants grown either in the presence or the absence of 120 mm NaCl. Transgenic plants showed higher Na+/H+ and, above all, K+/H+ transport activity in root intracellular membrane vesicles. Under K+ limiting conditions, transgenic plants enhanced root expression of the high‐affinity K+ uptake system HAK5 compared to untransformed controls. Furthermore, tomato overexpressing LeNHX2 showed twofold higher K+ depletion rates and half cytosolic K+ activity than untransformed controls. Under NaCl stress, transgenic plants showed higher uptake velocity for K+ and lower cytosolic K+ activity than untransformed plants. These results indicate the fundamental role of K+ homeostasis in the better performance of LeNHX2 overexpressing tomato under NaCl stress. 相似文献
12.
ELENA V. ERMILOVA ZHANNETA M. ZALUTSKAYA MAXIM M. NIKITIN TATYANA V. LAPINA EMILIO FERNÁNDEZ 《Plant, cell & environment》2010,33(6):1049-1056
The unicellular green alga Chlamydomonas reinhardtii is able to take up methylammonium/ammonium from the medium at different stages of its sexual life cycle. Vegetative cells and pre‐gametes mostly used a low‐affinity system (LATS) component, but gametes obtained after light treatment of N‐deprived pre‐gametes expressed both LATS and high‐affinity system (HATS) components for the uptake of methylammonium/ammonium. The activity of the LATS component was stimulated by light in only 5 min in a process independent of protein synthesis. By using the lrg6 mutant that produces sexually competent gametes in the dark, light effects on ammonium transport and gamete differentiation have been separately analysed. We have found light regulation of four Amt1 genes: Amt1; 1, Amt1; 2, Amt1; 4 and Amt1; 5. Whereas light‐dependent expression of Amt1; 1, Amt1; 2 and Amt1; 4 was independent of gametogenesis, and that of Amt1; 5 was activated in the lrg6 mutant, suggesting a connection between this transporter and the subsequent events taking place during gametogenesis. 相似文献
13.
EDUARDO CIRES CANDELA CUESTA MARÍA ÁNGELES REVILLA JOSÉ ANTONIO FERNÁNDEZ PRIETO 《Biological journal of the Linnean Society. Linnean Society of London》2010,101(2):251-271
The aim of this study was to assess genome size variation and multivariate morphometric analyses to ascertain cytotype distribution patterns and the morphological differentiation within the Ranunculus parnassifolius group in the Pyrenees and the Alps. Although divergences in nuclear DNA content among different species within a genus are widely acknowledged, intraspecific variation is still a somewhat controversial issue. Holoploid and monoploid genome sizes (C‐ and Cx‐values) were determined using propidium iodide flow cytometry in 125 plants of R. parnassifolius s.l. distributed across four European countries. Three different DNA ploidy levels were revealed in the study area: diploid (2n ~ 2x, 57.14%), triploid (2n ~ 3x, 1.19%), and tetraploid (2n ~ 4x, 41.67%). The mean population 2C‐values ranged from 8.15 pg in diploids to 14.80 pg in tetraploids, representing a ratio of 1 : 1.8. Marked intraspecific/interpopulation differences in nuclear DNA content were found. Diploid populations prevail in the Pyrenees, although tetraploid cytotypes were reported throughout the distribution area. In general, mixed‐cytotype populations were not found. The Spearman correlation coefficient did not reveal significant correlations between genome size and altitude, longitude, or latitude. Morphometric analyses and cluster analyses based on genome size variation revealed the presence of three major groups, which exhibited a particular biogeographical pattern. A new cytotype, DNA triploid, was found for the first time. Tetraploid populations showed constant nuclear DNA levels, whereas diploid populations from the Pyrenees, in which introgressive hybridization is suggested as a presumable trigger for genome size variation, did not. Scenarios for the evolution of geographical parthenogenesis in R. parnassifolius s.l. are discussed. Finally, the different levels of effectiveness between plant and animal reference standards are analysed. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 251–271. 相似文献
14.
15.
JEANETT CHAVEZ-ONTIVEROS ALFREDO D. MARTINEZ-ESPINOZA & JOSE RUIZ-HERRERA 《The New phytologist》2000,146(2):335-341
Using genetic crosses between single chs mutants of Ustilago maydis inoculated into maize ( Zea mays ) seedlings, two classes of double mutants affected in genes coding for chitin synthetases were isolated: chs3 / chs4 , and chs4 / chs5 . Analysis of the mutants showed almost no change in their phenotype compared with wild-type strains. Growth rate, effect of stress conditions, dimorphic transition and mating were not affected. The only salient differences were increased sensitivity to osmotics at acid pH, and decrease in chitin synthetase activity, especially when measured with CO2+ , and in chitin content. Most significant was a decrease in virulence, although this appeared to be due a factor unrelated to CHS genes. These data can be taken as further evidence that multigenic control of chitin synthetase in fungi operates as a safety mechanism to guarantee fungal viability in changing and hostile environmental conditions. 相似文献
16.
Hydrophilins from distant organisms can protect enzymatic activities from water limitation effects in vitro 总被引:2,自引:0,他引:2
17.
The lack of a comparative approach makes it impossible to determine the main factors influencing colonization and evolution in plants. Here we conducted the first comparative study of a characteristic Mediterranean lineage (white‐flowered Cistus) taking advantage of its well‐known phylogenetic relationships. A two‐scale approach was applied to address the hypothesis of higher levels of isolation in mountain than in lowland species. First, a time‐calibrated phylogeny using plastid sequences of Cistaceae suggested that the origin of Cistus species postdated both the refilling of the Mediterranean Sea (5.59–5.33 Ma) and the onset of the Mediterranean climate (3.2 Ma). Two hundred and sixty‐three additional, plastid sequences from 111 populations showed different numbers of haplotypes in C. laurifolius (7), C. monspeliensis (2) and C. salviifolius (7). Although haplotype sharing among disjunct populations was observed in all species, phylogeographic analyses revealed haplotype lineages exclusive to Europe or Africa only in the mountain species (C. laurifolius). Isolation by either geographical distance or sea barriers was not significantly supported for the lowland species (C. monspeliensis; C. ladanifer from a previous study). The same is true for the less habitat‐specific species of the lineage (C. salviifolius). Comparative phylogeography of the Cistus species leads us to interpret a general pattern of active colonization surpassing Mediterranean barriers. In contrast, ecological conditions (precipitation, temperature, soils) appear to have determined the distribution of the Cistus species of Mediterranean mountains. This study further provides molecular evidence for multiple colonization patterns in the course of successful adaptation of Cistus species to Mediterranean habitats. 相似文献
18.
JOSÉ ANTONIO FERNÁNDEZ PRIETO CARLOS AGUIAR EDUARDO DIAS MARÍA DE LOS ÁNGELES FERNÁNDEZ CASADO JUAN HOMET 《Botanical journal of the Linnean Society. Linnean Society of London》2008,158(3):522-533
The taxonomy and nomenclature of the genus Huperzia Bernh. in the Azores and Madeira have been reviewed. Plants collected in the Azores and Madeira were characterized morphologically. The independence between two endemic species common to Madeira and the Azores Islands –Huperzia suberecta (Lowe) Tardieu and Huperzia dentata (Herter) Holub – is clearly shown. A clear‐cut morphological separation between these taxa and Huperzia selago (L.) Bernh. ex Schrank & Mart. of continental Europe is established. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 522–533. 相似文献
19.
ZAMORANO JOSE Unidad de Investigacion Hospital San Pedro de Alcantara Avda Millan Astray Caceres ANN E KELLY JONATHAN AUSTRIAN HELEN Y WANG ACHSAH D KEEGAN 《Cell research》2001,(1)
INTRODUCTIONThe inappropriate enhancement of lymphocytesurviVal due to a block in programmed cell deathand/or an enhancement of entry into the cell cyclecan contribute to the abnormal expansion of clonesresulting in tumorigenesis or the breakdown of pe-ripheral self-toleranced, 2]. Proper lymphocytehomeostasis is critical for normal immune functionand is maintained by a complex series of cellularinteractions and the action of secreted cytokines.Illterleukin-4 (IL-4), a cytokine produced … 相似文献
20.
ANASS TERRAB JUAN L. GARCÍA-CASTAÑO JOSE M. ROMERO REGINA BERJANO CLARA DE VEGA SALVADOR TALAVERA 《Botanical journal of the Linnean Society. Linnean Society of London》2007,155(1):49-56
Nectar samples were collected from Silene colorata Poiret (Caryophyllaceae), in three different populations from south-western Spain: Zahara de la Sierra (Cádiz), Bornos (Cádiz) and Bormujos (Seville). Samples were analysed for amino acids by reverse-phase high-performance liquid chromatography with precolumn phenylisotiocyanate (PITC) derivatization. The method has the advantage of being highly sensitive, capable of detecting nanogram (ng) quantities of amino acids. Eighteen amino acids were identified and quantified. The mean number of amino acids in a nectar sample was 14 (SD = 2.8). Six amino acids (threonine, alanine, arginine, proline, tyrosine and methionine) were detected in all samples, accounting for 83% of the total amino acids content; proline and arginine were the most abundant amino acids, accounting for 40% and 20% of the total amino acids, respectively. The mean amounts of amino acids in nectar samples per population were 824, 782 and 356 µ m in Zahara de la Sierra, Bornos and Bormujos, respectively. Environmental variations such as temperature and sunlight are factors influencing the metabolic processes of nectar production. Our results may contradict the theory that the chemical constituents of floral nectar vary according to the kinds of pollinators. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 49–56. 相似文献