全文获取类型
收费全文 | 321篇 |
免费 | 17篇 |
国内免费 | 24篇 |
专业分类
362篇 |
出版年
2024年 | 4篇 |
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 16篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 5篇 |
2017年 | 12篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2014年 | 16篇 |
2013年 | 27篇 |
2012年 | 9篇 |
2011年 | 9篇 |
2010年 | 7篇 |
2009年 | 11篇 |
2008年 | 12篇 |
2007年 | 11篇 |
2006年 | 18篇 |
2005年 | 18篇 |
2004年 | 5篇 |
2003年 | 11篇 |
2002年 | 6篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1996年 | 12篇 |
1995年 | 3篇 |
1994年 | 11篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有362条查询结果,搜索用时 0 毫秒
101.
Vitamin C, E. carotenes and major economic characters in hips of 38 species of Rosa from China were studied. There were considerable variations in vitamin C contents in the genus. The maximum amount was found in the hips of R. tsinglingensis (2576 mg/100 g), and the minimum in these of R. deqenensis (49 mg/100 g). Carotene contents varied from 0.06 to 19.24 mg/100 g. being lowest in R. xanthina, and highest in R. henryi. Difference was slight in vitamin E contents ranged from 1.34 mg/100 g (R. xanthina) to 3.86 mg/100 g (R. bracteata). Statistical analysis of 54 species of subgenus Rosa from wild populations in China has evidenced a close relationship between the division of sections and the vitamin C contents in mature hips, such as that vitamin C contents in species of Sect. Cinnamoneae and Microphylla were quite high with an average of more than 1800 mg/100 g. 相似文献
102.
A decrease in CO2 uptake, an increase in leaf starch and sucrose content and a decrease in the content of reducing sugars were found in rose ( Rosa hybrida cvs: Sonia and Golden Times) plants exposed to lower night temperature (12°C) in comparison with those grown at 18°C. These responses were not present when plants were grown under a night temperature regime of alternating temperature, 2 h at 18°C followed by 2 h at 12°C for 3 repetitive periods of a total of 12 h. The export of labelled carbon from the source leaves and translocation into the adjacent axillary buds were inhibited by lower night temperature, but not by the alternating temperature regime. The translocation of labelled carbon toward the basal plant parts was promoted by the lower temperature but not by alternating temperature. The partitioning of labelled carbon between the 2 uppermost lateral buds was also affected by the night temperature regime. 相似文献
103.
B. von Malek W. E Weber T. Debener 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,101(5-6):977-983
Blackspot resistance in the tetraploid rose genotype 91/100–5 had been characterised previously as a single dominant gene
in duplex configuration. In the present study a tetraploid progeny (95/3) segregating for the presence of the blackspot resistance
gene Rdr1 were screened with 868 RAPD and 114 AFLP primers/primer combinations. Seven AFLP markers were found to be linked to Rdr1 at distances between 1.1 and 7.6 cM. The most closely linked AFLP marker was cloned and converted into a SCAR marker that
could be screened in a larger population than the original AFLP and was linked at a distance of 0.76 cM. The cloned fragment
was used as an RFLP probe to locate the marker on a chromosome map of diploid roses. This is the first report of markers linked
to a resistance gene in roses, and the possibilities of using them for a marker-assisted selection for blackspot resistance
as well as for map-based cloning approaches are discussed.
Received: 23 December 1999 / Accepted: 25 March 2000 相似文献
104.
105.
From the fruit of Rosa davidii Crep., eleven compounds were isolated and identified by spectral evidence, viz. 2α,3β,19β-trihydroxyl-olean-12-en-28-oic acid (1), 2α,3β-dihydroxyl-urs-28(13)-lactone (2), arjunic acid (3), euscaphic acid (4), 2α,3β-dihydroxyl-urs-12-en-28-oic acid (5), oleanolic acid (6), kaempferol (7), tiliroside (8), quercetin (9), daucosterol (10) and β-sitosterol (11). Among them, 1 and 2 were new compounds. 相似文献
106.
Clones of Rosa damascena Mill. cv. Gloire de Guillan, selected for growth in solid medium containing 56 m M NaClO3 , were studied to determine the reason for their resistance to this toxic salt. The cells grew on medium containing nitrate as the only nitrogen source, and they synthesized nitrate reductase (EC 1.6.6.2) in the presence of nitrate. The cells were resistant in the presence of nitrate. However, their resistance was greatly increased by the presence of glutamate in the medium. The cells took up [36 Cl]-ClO3 - and reduced it to ClO2 − , but the fraction of ClO3 − that they reduced under our experimental conditions was less than that reduced by wild type. The slower production of ClO2 − apparently accounted for the resistance of the cells to ClO3 − . We suggest several possible reasons for the low rate of reduction of ClO3 − . 相似文献
107.
108.
109.
Selection of non‐target tephritids for risk evaluation in classical biocontrol programmes against the olive fruit fly 下载免费PDF全文
A. Cobo M. González‐Núñez I. Sánchez‐Ramos S. Pascual 《Journal of Applied Entomology》2015,139(3):179-191
The olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), is the key pest of olives (Olea europaea L.). Classical biological control against this insect was previously attempted in Spain with Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae), with very limited success. Other parasitoids are now available for new classical biological control programmes. Before release of exotic parasitoids, an assessment of their potential impact on non‐target species is required. Surveys were conducted in different olive groves in south‐eastern Madrid to study wild tephritids associated with Asteraceae plants. We recorded plant species and their abundance and collected flower heads to identify and quantify tephritid species. Fruits from Rosa canina L. were also collected. After a multicriteria analysis (MCA), we propose Urophora hispanica Strobl, U. stylata (Fabricius) and Carpomya schineri (Loew) as candidates for further risk assessment experiments. Additional information on new associations between tephritid flies and Asteraceae plants and on autochthonous Hymenoptera parasitizing tephritids is provided. 相似文献
110.
严俊鑫;关桦楠;迟德富;张永强;张丹 《植物研究》2013,33(4):499-503
为研究重瓣玫瑰(Rosa rugosa ‘plena’)的诱导抗虫性,采用机械损伤方式诱导处理重瓣玫瑰,研究机械损伤对重瓣玫瑰叶片防御酶活性的影响。结果表明,机械损伤可诱导重瓣玫瑰叶片苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)、过氧化物酶(POD)活性的增加,PPO、POD活性先升高后下降,PAL活性的升高持续时间较长。T3(打孔损伤,3孔/叶)处理为最适的损伤程度,诱导的PAL、PPO、POD活性分别在第7、3、5天达到最高值。因此认为,采用适度地损伤能够诱导重瓣玫瑰较高的防御酶活性,提高植株的防御能力。 相似文献