全文获取类型
收费全文 | 109篇 |
免费 | 11篇 |
国内免费 | 19篇 |
出版年
2024年 | 1篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 1篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 7篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 7篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1976年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有139条查询结果,搜索用时 31 毫秒
1.
Restriction pattern analysis of deoxyribonucleic acid isolated from callus and cell suspension of actinorhizal and non-actinorhizal Betulaceae 总被引:1,自引:0,他引:1
Using cell suspensions, a method was elaborated to isolate high-molecular-weight genomic deoxyribonucleic acid (DNA; 65 MDa or more) from members of the Betulaceae: Alnus incana (L.) Moench, Alnus glutinosa (L.) Gaertn. and Betula papyrifera Marsh. The method was also effective for isolation of DNA from callus cells. Based on the chemical lysis of protoplasts, this procedure yielded 130 μg (callus) to 250 μg (cell suspension) of DNA (g fresh cells)−1 , with a ratio A200 /A28 of 1.7–2.0. The purified DNA obtained, formed distinct bands when restricted fragments were electrophoresed. Among the 10 endonucleases used for restriction analysis of Alnus glutinosa, Alnus incana and Betula papyrifera genomes, PvuI1 (EC 3.1.23.33) was unique in giving identical patterns for the two Ainus species. An unusual pattern occurred when Al-2 DNA was restricted with Ava II (EC 3.1.23.4). It formed a ladder with a repeating fragment unit of 181 base pairs long. With the enzymes tested, no differences in restriction patterns were observed among clones of Alnus incana (AI-2 vs AI-2), Betula papyrifera (BP-4 vs BP-8) and subclones of Ainus glutinosa AG-1 (PLFJ709 vs LF1709), suggesting genetic stability of the Betulaceae cultures. 相似文献
2.
A true hemoglobin (Hb) was shown to be present in the root nodules of Alnus glutinosa L. After purification by gel filtration and ion exchange, the Hb formed a stable complex with oxygen. This oxygen complex could then be converted to carboxyhemoglobin by treatment with CO. Optical absorption spectra typical of Hb were observed. The molecular weight was estimated to be 15 100 by gel filtration, and 18 300 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The Hb was largely insoluble when the initial homogenization was done in the absence of a detergent. Under these conditions much of the Hb appears to be associated with clusters of Frankia , the nitrogen-fixing actinomycete that infects plant cells within the nodules. The exact localization of the Hb in vivo is uncertain. The relatively low average concentration of Hb in Alnus nodules suggests that it is either confined to a relatively small fraction of total nodule volume, or has a function other than facilitation of O2 transport. 相似文献
3.
Relationship between the chromatoid body and the acrosomal system in early spermatids of Myxine glutinosa L. 总被引:1,自引:0,他引:1
Summary A transient close relationship between the chromatoid body and the developing acrosome is demonstrated in early spermatids of Myxine glutinosa.This work was supported by the Norwegian Research Council for Science and Humanities (NAVF, Grant Nr. D 61.44) and the Austrian Fonds zur Förderung der wissenschaftlichen Forschung, Projekt 2183 相似文献
4.
《Bioscience, biotechnology, and biochemistry》2013,77(4):910-912
We previously isolated from Nicotiana glutinosa leaves three distinct cDNA clones, NGR1, NGR2, and NGR3, encoding a wound-inducible RNase NW, and putative RNases NGR2 and NGR3, respectively. In this study, we produced RNases NW and NGR3 in Escherichia coli and purified them to homogeneity. RNase NGR3 had non-absolute specificity toward polynucleotides, although RNase NW preferentially cleaved polyinosinic acid (Poly I). Both RNases NW and NGR3 were more active toward diribonucleoside monophosphates ApG, CpU, and GpU. Furthermore, kinetic parameters for RNase NW (K m, 0.778 mM and k cat, 1938 min?1) and RNase NGR3 (K m, 0.548 mM and k cat, 408 min?1) were calculated using GpU as a substrate. 相似文献
5.
以地黄为材料,通过分析地黄转录组数据,设计特异性引物,克隆了地黄牻牛儿基牻牛儿基焦磷酸合酶(geranylgeranyl pyrophosphate synthase,GGPPS)基因的cDNA序列,命名为RgGGPPS1,GenBank登录号为KU258808。同时在生物信息学分析的基础上,进行原核表达、纯化以及组织特异性表达分析。结果显示:(1)RgGGPPS1基因开放阅读框为987 bp,编码328个氨基酸。(2)生物信息学分析结果显示,RgGGPPS1蛋白含有2个富含天冬氨酸的基序(DDXXXXDD和DDXXD),与芝麻等双子叶植物中的GGPPS蛋白相似性较高。(3)利用构建的原核表达载体pET 32a RgGGPPS1在大肠杆菌BL21(DE3)菌株中成功表达RgGGPPS1重组蛋白,采用Ni2+亲和层析得到了纯化的RgGGPPS1重组蛋白。(4)荧光定量PCR结果显示,RgGGPPS1基因在根中表达量最高,叶、茎中表达量较低。研究结果为进一步研究RgGGPPS1基因在地黄环烯醚萜苷生物合成途径中的功能奠定了基础。 相似文献
6.
7.
8.
Rehmannia glutinosa seedlings were pretreated with choline chloride (CC) in concentrations of 0, 0.7, 2.1 and 3.5 mM, and then subjected to drought
and rewatering treatment to study the effects of CC on the generation of reactive oxygen species (O2−, H2O2), lipid peroxidation, proline accumulation, water status and photosynthesis. The results showed that pretreatment with CC
alleviated the inhibition of SOD and APX activity caused by drought stress, and therefore, the rate of O2− production and H2O2 concentration were reduced and lipid peroxidation decreased in pretreated plants. CC pretreatment also accelerated accumulation
of proline, maintained higher Ψw and RWC, deferred leaf water loss during drought stress and retarded the drop in proline
concentration after rewatering. Consequently, drought-induced decreases in Fm/F0, Fv/Fm, ΦPS2, qP, and A and increase in qNP were inhibited and the recovery of photosynthesis after rewatering was quicker in pretreated plants. Although differences
in Fv/Fm, ΦPS2 and qP between treatments were not significant, there was a general trend that the effects of CC increased with the rise of its
concentrations. The data suggested that 2.1 mM of CC be suitable for alleviating lipid peroxidation, promoting proline accumulation,
retarding leaf water loss and improving photosynthesis of R. glutinosa seedlings under drought stress. 相似文献
9.
地黄属种间亲缘关系研究 总被引:10,自引:1,他引:9
对地黄属6个物种进行了形态解剖学观察、染色体计数、核核糖体内转录间隔区(ITS)序列分析.结果表明,茎的高度、幼叶形态、花萼和花冠形态及颜色、种子千粒重和大小、外种皮网壁厚度、外种皮内侧网纹直径等均是该属内分类的可靠依据.高地黄与裂叶地黄在外部形态及解剖结构的各个方面均极为近似,地黄与茄叶地黄间也存在较大的相似性.茄叶地黄、高地黄、湖北地黄、天目地黄的染色体数目,分别为n=28、14、14、14,确认地黄和茄叶地黄为属内四倍体物种,其余种均为二倍体.ITS测序分析显示,地黄属为单系起源,天目地黄与湖北地黄、高地黄与裂叶地黄、地黄与茄叶地黄构成属内3个分支,与形态学及细胞学研究结果一致.研究认为,天目地黄与湖北地黄有较近的亲缘关系;高地黄和裂叶地黄应为同一物种;地黄与茄叶地黄是属内进化水平最高的类群. 相似文献
10.