全文获取类型
收费全文 | 725篇 |
免费 | 44篇 |
国内免费 | 68篇 |
出版年
2023年 | 12篇 |
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 19篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 19篇 |
2016年 | 18篇 |
2015年 | 15篇 |
2014年 | 19篇 |
2013年 | 39篇 |
2012年 | 11篇 |
2011年 | 17篇 |
2010年 | 20篇 |
2009年 | 30篇 |
2008年 | 40篇 |
2007年 | 32篇 |
2006年 | 42篇 |
2005年 | 30篇 |
2004年 | 35篇 |
2003年 | 29篇 |
2002年 | 21篇 |
2001年 | 26篇 |
2000年 | 24篇 |
1999年 | 24篇 |
1998年 | 30篇 |
1997年 | 27篇 |
1996年 | 13篇 |
1995年 | 23篇 |
1994年 | 10篇 |
1993年 | 13篇 |
1992年 | 18篇 |
1991年 | 18篇 |
1990年 | 31篇 |
1989年 | 18篇 |
1988年 | 15篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有837条查询结果,搜索用时 15 毫秒
121.
122.
The separate or combined effects of Pichia membranaefaciens and salicylic acid (SA) on the control of blue and green mold decay in citrus fruits were investigated. Results indicate that combining P. membranaefaciens (1 × 108 CFU ml−1) with SA (10 μg ml−1) either in a point-inoculated or dipped treatment provided a more effective control of blue and green mold than separately applying yeast or SA. SA (10 μg ml−1) did not significantly affect P. membranaefaciens growth in vitro but slightly increased the yeast population in fruit wounds. P. membranaefaciens plus SA effectively enhanced the phenylalanine ammonia-lyase, peroxidase, polyphenoloxidase, chitinase, and β-1,3-glucanase activities and stimulated the synthesis of phenolic compounds. The combined treatment did not impair quality parameters such as weight loss or titratable acidity, but resulted in low average natural infection incidence and increased total soluble solids and ascorbic acid contents in citrus fruits after 14 d at 20 °C. 相似文献
123.
北缘地区柑桔生态区划模糊决策系统 总被引:3,自引:0,他引:3
以年平均极端最低气温、活动积温、最冷月平均气温、年平均气温等作为区划决策的重要指标,综合年降水量、最低气温≤-9℃年平均日数及地貌与海拔、水体调节、冷风屏障和土壤营养丰度、PH值等立地条件,建立了北缘地区柑桔生态区划决策系统.引入L-R型模糊数,确立了模糊识别模式,并把模糊推理模型放在知识库里,将精确推理与模糊推理置于同一系统中进行复合推理,使决策系统具有更广泛的实用性.以安徽柑桔生态区划为例,对系统进行了验证.本系统的开发为北缘地区发展柑桔生产提供了决策工具. 相似文献
124.
Citrus phylogeny and genetic origin of important species as investigated by molecular markers 总被引:19,自引:0,他引:19
E. Nicolosi Z. N. Deng A. Gentile S. La Malfa G. Continella E. Tribulato 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(8):1155-1166
Citrus phylogeny was investigated using RAPD, SCAR and cpDNA markers. The genotypes analyzed included 36 accessions belonging
to Citrus together with 1 accession from each of the related genera Poncirus, Fortunella, Microcitrus and Eremocitrus. Phylogenetic analysis with 262 RAPDs and 14 SCARs indicated that Fortunella is phylogenetically close to Citrus while the other three related genera are distant from Citrus and from each other. Within Citrus, the separation into two subgenera, Citrus and Papeda, designated by Swingle, was clearly observed except for C. celebica and C. indica. Almost all the accessions belonging to subgenus Citrus fell into three clusters, each including 1 genotype that was considered to be a true species. Different phylogenetic relationships
were revealed with cpDNA data. Citrus genotypes were separated into subgenera Archicitrus and Metacitrus, as proposed by Tanaka, while the division of subgenera Citrus and Papeda disappeared. C. medica and C. indica were quite distant from other citrus as well from related genera. C. ichangensis appeared to be the ancestor of the mandarin cluster, including C. tachibana. Lemon and Palestine sweet lime were clustered into the Pummelo cluster led by C. latipes. C. aurantifolia was located in the Micrantha cluster. Furthermore, genetic origin was studied on 17 cultivated citrus genotypes by the same
molecular markers, and a hybrid origin was hypothesized for all the tested genotypes. The assumptions are discussed with respect
to previous studies; similar results were obtained for the origin of orange and grapefruit. Hybrids of citron and sour orange
were assumed for lemon, Palestine sweet lime, bergamot and Volkamer lemon, while a citron × mandarin hybrid was assumed for
Rangpur lime and Rough lemon. For Mexican lime our molecular data indicated C. micrantha to be the female parent and C. medica as the male one.
Received: 5 October 1999 / Accepted: 3 November 1999 相似文献
125.
沙田柚自交不亲和花柱糖蛋白产生的时空关系 总被引:7,自引:0,他引:7
用辣根过氧化物酶标 Con A电镜细胞化学方法研究沙田柚不同发育时期的花柱通道细胞中糖蛋白的合成 ,分布和运输途径的动态变化。四分体期至开花期 ,在沙田柚花柱通道细胞中 ,内质网 (ER)合成糖蛋白呈颗粒状定位于核膜腔 ,内质网膜腔 ,质膜与细胞壁之间电子透明层中。授粉后 1~ 3d,内质网结构形态改变 ,由完整圆形变为开放 ,并囊泡化 ,大量线粒体集中于囊泡区 ,形成类似于哺乳动物腺外分泌细胞的高尔基区 ,内质网合成的糖蛋白在高尔基区膜囊中经糖基转移酶作用进一步浓缩凝结 ,形成与识别有关的糖蛋白 ,经高尔基小泡运送至通道细胞外壁。讨论了定位于通道细胞外壁的糖蛋白在沙田柚配子体型不亲和识别中的作用及与识别部位的关系。 相似文献
126.
127.
128.
Stefania Raimondo Ornella Urzì Serena Meraviglia Marta Di Simone Anna Maria Corsale Nima Rabienezhad Ganji Antonio Palumbo Piccionello Giulia Polito Elena Lo Presti Francesco Dieli Alice Conigliaro Riccardo Alessandro 《Journal of cellular and molecular medicine》2022,26(15):4195
Chronic inflammation is associated with the occurrence of several diseases. However, the side effects of anti‐inflammatory drugs prompt the identification of new therapeutic strategies. Plant‐derived extracellular vesicles (PDEVs) are gaining increasing interest in the scientific community for their biological properties. We isolated PDEVs from the juice of Citrus limon L. (LEVs) and characterized their flavonoid, limonoid and lipid contents through reversed‐phase high‐performance liquid chromatography coupled to electrospray ionization quadrupole time‐of‐flight mass spectrometry (RP‐HPLC–ESI‐Q‐TOF‐MS). To investigate whether LEVs have a protective role on the inflammatory process, murine and primary human macrophages were pre‐treated with LEVs for 24 h and then were stimulated with lipopolysaccharide (LPS). We found that pre‐treatment with LEVs decreased gene and protein expression of pro‐inflammatory cytokines, such as IL‐6, IL1‐β and TNF‐α, and reduced the nuclear translocation and phosphorylation of NF‐κB in LPS‐stimulated murine macrophages. The inhibition of NF‐κB activation was associated with the reduction in ERK1‐2 phosphorylation. Furthermore, the ability of LEVs to decrease pro‐inflammatory cytokines and increase anti‐inflammatory molecules was confirmed ex vivo in human primary T lymphocytes. In conclusion, we demonstrated that LEVs exert anti‐inflammatory effects both in vitro and ex vivo by inhibiting the ERK1‐2/NF‐κB signalling pathway. 相似文献
129.
Enzymatic Process Enhances the Flavour Profile and Increases the Proportion of Esters in Citrus Essential Oils
下载免费PDF全文
![点击此处可从《化学与生物多样性》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Kun Zhang Ying Lin Zhou‐Jian Diao Wei‐Hua Zhang Sui‐Ping Zheng Shu‐Li Liang Shuang‐Yan Han 《化学与生物多样性》2017,14(11)
Citrus essential oils (CEOs) are important flavors in the food and confectionary industries. A lipase process was proposed for enhancing the flavor profiles and increasing the proportions of esters in CEOs. The effects of the enzymatic process were explored by detecting the constituents of the CEOs of American sweet orange oil (ASO) and Brazil mandarin oil (BMO) through GC/MS and sensory evaluation by a trained panel, and positive effects were confirmed by both methods. A further eleven kinds of CEOs were treated via the lipase process and increments of 10 – 1170% were achieved in the proportions of esters, which were mostly ethyl esters. Enhancement in fruity odor, especially the top note, was demonstrated by all CEOs after enzymatic processing. All CEOs were tested for antimicrobial activities, and only ASO displayed fairly ideal antimicrobial activities. Meanwhile, modified ASO showed a certain increase in antimicrobial activities. This methodology might be considered a sustainable route for acquiring ‘natural’ essential oils with enhanced flavor profiles and simultaneously enhancing the comprehensive utilization of citrus fruits. 相似文献
130.
Salt and oxidative stress: similar and specific responses and their relation to salt tolerance in Citrus 总被引:45,自引:0,他引:45
Salt damage to plants has been attributed to a combination of several factors including mainly osmotic stress and the accumulation
of toxic ions. Recent findings in our laboratory showed that phospholipid hydroperoxide glutathione peroxidase (PHGPX), an
enzyme active in the cellular antioxidant system, was induced by salt in citrus cells and mainly in roots of plants. Following
this observation we studied the two most important enzymes active in elimination of reactive oxygen species, namely, superoxide
dismutase (SOD) and ascorbate peroxidase (APX), to determine whether a general oxidative stress is induced by salt. While
Cu/Zn-SOD activity and cytosolic APX protein level were similarly induced by salt and methyl viologen, the response of PHGPX
and other APX isozymes was either specific to salt or methyl viologen, respectively. Unlike PHGPX, cytosolic APX and Cu/Zn-SOD
were not induced by exogenously added abscisic acid. Salt induced a significant increase in SOD activity which was not matched
by the subsequent enzyme APX. We suggest that the excess of H2O2 interacts with lipids to form hydroperoxides which in turn induce and are removed by PHGPX. Ascorbate peroxidase seems to
be a key enzyme in determining salt tolerance in citrus as its constitutive activity in salt-sensitive callus is far below
the activity observed in salt-tolerant callus, while the activities of other enzymes involved in the defence against oxidative
stress, namely SOD, glutathione reductase and PHGPX, are essentially similar.
Received: 10 January 1997 / Accepted: 28 May 1997 相似文献