全文获取类型
收费全文 | 170篇 |
免费 | 5篇 |
国内免费 | 19篇 |
专业分类
林业 | 2篇 |
农学 | 134篇 |
5篇 | |
综合类 | 24篇 |
农作物 | 20篇 |
水产渔业 | 2篇 |
畜牧兽医 | 1篇 |
园艺 | 3篇 |
植物保护 | 3篇 |
出版年
2024年 | 2篇 |
2021年 | 1篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2012年 | 8篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 2篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 8篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 9篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有194条查询结果,搜索用时 640 毫秒
1.
Variation was investigated in 110 doubled haploid (DH) lines of wheat derived from wheat × maize crosses. Field observation revealed visible variations in 15 DH2 lines such as extreme dwarfism, low seed fertility, alteration of spike type and stripes. Six agronomic traits, i.e., heading date, spike number/ plant, culm length, spike length, seed fertility and grain weight were statistically analyzed in the DH2 and DH3 generations. Out of the 88 DH2 lines/DH3 groups, 26 %/64 % showed significant differences from the parental variety in the means of one or more traits. Ranges of the DH3 lines were larger than those of the DH2 lines, except for spike number/plant. Furthermore, analyses of variance within and between DH lines showed the presence of heterogeneity/heterozygosity in the DH2 lines/plants. These results indicated the occurrence of gametoclonal variation in the DH lines. It is considered that most of the variations detected were due to the colchicine treatment rather than to the 2,4-D treatment or in vitro culture. 相似文献
2.
白羊草光合特性及非结构性碳水化合物含量对 CO2 浓度倍增和干旱胁迫的响应 总被引:1,自引:0,他引:1
3.
Development of sorghum hybrids can immensely benefit from an enhanced anther culture protocol since the resultant doubled haploids would accelerate, as in other major cereal crops, the attainment of homozygosity and fixation of alleles. Production of the hybrids that have got high yielding, stress tolerance and other traits of industrial significance in a shorter time as compared to the current trend can hence be realized. This review presents the advances that have been made in the development of such a protocol, with closer attention to androgenic induction components of pre-treatment, culture media composition and conditions as well as ploidy determination and eventual chromosome doubling. From the findings of this review, it is clear that further work is desired to ensure a protocol, that to a large degree, breaks the genotype dependency trend that has been widely cited to impede the usability of the tested protocols. 相似文献
4.
【目的】阐明影响小麦籽粒淀粉基因/QTL的时空表达和动态变化情况,为运用条件QTL更好地揭示小麦籽粒淀粉动态积累的基因表达提供参考。【方法】本研究以小麦品种花培3号和豫麦57构建的168个双单倍体(doubled haploid, DH)群体为材料,在6个不同的环境下种植,分别在花后12 d、17 d、22 d、27 d和32 d取样,对小麦籽粒淀粉含量(GSC)积累的条件和非条件QTL进行分析。【结果】在籽粒灌浆的5个时期,一共检测到7个非条件QTL和4个条件QTL,没有一个条件QTL能在测定的5个时期都有效应。7个非条件QTL分别分布在2A、3A、3B、4A、5D染色体上,其中QGsc4A在整个灌浆过程都能表达,5个时期的表型变异贡献率分别为13.57%、16.57%、21.96%、22.53%、22.90%。4个条件QTL中,QGsc4A在花后12 d、17 d、32 d均能检测到,总贡献率为21.80%,对籽粒淀粉积累的净增长量起主要作用。其它非条件QTL和条件QTL只在一个或几个阶段出现且效应值较小,花后27 d没有检测到条件QTL。【结论】控制GSC积累的数量性状基因以一定的时空方式表达,小麦籽粒淀粉积累的QTL动态分析,可以了解小麦籽粒淀粉积累的遗传规律及其对小麦籽粒发育的影响,为小麦产量和品质形成的分子基础的深入研究提供参考。 相似文献
5.
CO2浓度倍增下毛竹光合作用对光照强度的季节响应 总被引:2,自引:1,他引:1
采用Li-6400测定了在短期CO2浓度倍增下毛竹光合作用对光照强度的季节响应,并对比同一测定毛竹在相同时期大气CO2浓度下的光响应曲线特征,结果表明:CO2浓度的增加促使毛竹最大净光合速率和光饱和点升高,光补偿点下降,而对光合量子效率的影响因季节而异,在夏、秋两季光合量子效率升高,冬季持平,春季降低,但全年来看还是具有促进作用;在相同的光照强度下,CO2浓度的倍增会使毛竹的净光合速率和水分利用率升高,而蒸腾速率和暗呼吸速率下降。CO2浓度倍增后,各光合生理特征参数的季节变化基本和大气CO2浓度下的季节变化相同,均与毛竹叶片的生理活性密切相关;而在不同季节,毛竹对CO2浓度升高的响应差异性是造成季节变化规律稍有不同的主要原因之一,证实了植物对短期CO2浓度升高的光合生理响应行为。 相似文献
6.
P. Castagnone-Sereno M. Bongiovanni A. Palloix A. Dalmasso 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(6):585-590
Experiments were designed to analyze the relationships between the root-knot nematodeMeloidogyne incognita and resistant tomato and pepper genotypes. From a natural avirulent isolate, near-isogenic nematode lineages were selected with virulence either against the tomatoMi resistance gene or the pepperMe3 resistance gene. Despite the drastic selection pressure used, nematodes appeared unable to overcome the pepperMe1 gene, therefore suggesting some differences in the resistance conferred byMe1 andMe3 in this species. Nematodes virulent onMi-resistant tomatoes were not able to reproduce onMe1-resistant nor onMe3-resistant peppers, and nematodes virulent onMe3-resistant peppers were not able to reproduce onMi-resistant tomatoes nor onMe1-resistant peppers. These results clearly demonstrate the specificity ofM. incognita virulence against resistance genes from both tomato and pepper, and indirectly suggest that gene-for-gene relationships could occur between these two solanaceous crops and the nematode. 相似文献
7.
大白菜游离小孢子培养胚胎发生中的加倍机制 总被引:6,自引:0,他引:6
利用Leica体视显微镜, DAPI荧光染色观察比较大白菜小孢子正常发育为成熟花粉粒与游离小孢子培养胚胎发生细胞核的分裂方式, 探讨大白菜游离小孢子培养胚胎发生及其自然加倍的机理。观察结果显示以B途径为主要发育途径的大白菜小孢子, 胚胎发生的启动机制是热激诱导下单倍体小孢子体积膨大, 染色体发生自然加倍, 从而激发小孢子进入孢子体发育途径; 大白菜小孢子胚再生植株具有较高的自然加倍率, 这与小孢子培养热激诱导激发小孢子单核自然加倍为二倍体密切相关。 相似文献
8.
Paula Filomena Martins-Lopes Henrique Guedes-Pinto Olinda Pinto-Carnide John Snape 《Euphytica》2001,121(3):265-271
Barbela is an old Portuguese landrace of wheat that is highly genetically heterogeneous. Different Barbela populations when
subjected to aluminium stress show variable levels of tolerance. In order to study the inheritance of this character, doubled
haploid (DH) lines were developed. These DH were obtained by intergeneric crosses of 14 different lines of Barbela with maize.
During this process the efficiency of the technique was evaluated and suggestions for its improvement were obtained. Several
parameters were studied in the crosses: % of crossability, % of embryos per florets pollinated and % of embryos per seed set.
The different genotypes of Barbela showed significant variation for the parameters analysed. When the reciprocal crosses were
analysed, no differences were found, indicating that cytoplasm differences do not influence the parameters of DH production.
However, different spikelet positions (lower, middle and upper) gave highly significant differences in all parameters analysed.
Highest success frequencies were obtained for pollinated spikelets in the middle of the spike. This can indicate that concentrating
on the middle part of the spike can increase the frequency of DHs obtained using inter generic crosses of wheat with maize.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
Rong-Cai Yang Mohan R. Thiagarajah Vipan K. Bansal Gary R. Stringam M. Habibur Rahman 《Euphytica》2006,148(3):217-225
Summary The segregation and linkage between glufosinate (transgenes ‘Rf3’ and ‘T177’) and blackleg resistance genes in canola (Brassica napus L.) were assessed using F1 microspore-derived doubled haploid (DH) populations from four crosses including reciprocals, two involving the transgene ‘Rf3’ and the other two involving the transgene ‘T177’. To relax the assumption of no segregation distortion required for the conventional analysis of segregation and linkage, we employed Bailey's analysis that allows detecting segregation distortion at linked loci. The significant departures from the 1:1 segregation were detected in the crosses involving the transgene ‘T177’ but not in the crosses involving the transgene ‘Rf3’. The apparent deficit of the herbicide tolerant DH lines in the crosses with the transgene ‘T177’ is likely due to differential selection against the gametes carrying ‘T177’ during microspore culture. The linkage was strong between blackleg resistance and the transgene ‘Rf3’ but weak or absent between blackleg resistance and the transgene ‘T177’, suggesting that the two transgenes are probably inserted into distant regions of the genome. The observed linkage offers an opportunity to develop new canola cultivars with both glufosinate tolerance conferred by transgene ‘Rf3’ and blackleg resistance. 相似文献
10.
Enhanced anther culture efficiency of indica rice (Oryza sativa L.) through modification of the culture media 总被引:1,自引:0,他引:1
The production of microspore-derived green plants from anther culture of indica rice is generally very low compared with japonica cultivars. A modified anther culture medium, consisting of a higher KNO3 content (31 mm ) and casein hydrolysate (CH, 500 mg/1) but without ammonium salts, was tested in comparison with a medium consisting of the widely-used N6 medium nitrogen background, using four indica × indica F1 hybrids as test materials. Green plant regeneration frequency was at least three-fold higher in the microspore-calli derived from the former medium than in those derived from the modified N6 medium. More than 700 microspore-derived plants were raised in the field. Another study was carried out using indica × japonica and indica × javanica F1 hybrids. The results indicated that a medium with higher (3.5 mm ) ammonium sulphate may induce a higher frequency of anthers with microspore-calli but not necessarily lead to a larger number of green-plant regenerating calli. Subsequently, using the indica cv. ‘IR-43’ as the test material, use of a lower level (1.75 mm ) of (NH4)2SO4, in addition to KNO3 (31 mm ), was found to be better than CH (500 mg/l) for anther-response as well as green plant regenerability of the derived microspore-calli. Nitrate-nitrogen or ammonium-nitrogen alone elicited poor response. Twenty-five media involving combinations of KNO3 (20–34 mm ) and (NH4)2SO4 (1–3 mm ) were tested for their effects on anther response. Combinations involving KNO3 (31–34 mM) and (NH4)2SO4 (2.0–2.5 mm ) were found superior not only for achieving greater anther response but also, for subsequent green-plant regeneration. This contrasts with the 28 mm of KNO3 and 3.5 mm of (NH4)2SO4 in the widely-used N6 medium developed for japonica rice. Other than potassium nitrate and ammonium sulphate, and potassium phosphate to some extent, the levels of other inorganic salts tested did not make any significant difference to the process of anther response. Based on these results, modified media with three levels of ammonium sulphate were tested for anther culture efficiency of indica × japonica and indica × javanica derivatives (F3s). Microspore-calli derived from a medium of a lower (1.75 mm ) level of (NH4)2SO4 showed a higher regeneration potential overall than those derived from a higher (3.5 mm ) level. A revised medium has been suggested, on the basis of these results, for the realization of improved anther culture efficiency and, consequently, improved feasibility of using doubled haploids in genetic and breeding research with indica rice. 相似文献