全文获取类型
收费全文 | 234篇 |
免费 | 14篇 |
出版年
2023年 | 2篇 |
2021年 | 7篇 |
2020年 | 2篇 |
2019年 | 7篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 10篇 |
2015年 | 10篇 |
2014年 | 14篇 |
2013年 | 18篇 |
2012年 | 20篇 |
2011年 | 13篇 |
2010年 | 9篇 |
2009年 | 7篇 |
2008年 | 18篇 |
2007年 | 13篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 13篇 |
2003年 | 10篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有248条查询结果,搜索用时 31 毫秒
31.
32.
33.
34.
In vitro induction of multiple shoots and plant regeneration in cotton (Gossypium hirsutum L.) 总被引:5,自引:0,他引:5
D. C. Agrawal A. K. Banerjee R. R. Kolala A. B. Dhage A. V. Kulkarni S. M. Nalawade S. Hazra K. V. Krishnamurthy 《Plant cell reports》1997,16(9):647-652
Induction of multiple shoots in cotton (Gossypium hirsutum L. cv. Anjali-LRK 516) has been achieved with cotyledonary nodes devoid of cotyledons and apical meristems. Explants from 35-day-old seedlings yielded the maximum number of shoots (4.7 shoots/explant) using Murashige and Skoog (MS) basal medium supplemented with 6-benzylaminopurine and kinetin (2.5 mg/1 each). Explants from 35-day-old seedlings raised in glass bottles produced a higher number of multiple shoots (8.3 shoots/explant) than those grown in glass tubes and cultured on the same shoot induction medium. Elongation of multiple shoots was obtained on liquid or agar MS basal medium without phytohormones. In vitro shoots were rooted on half-strength agar-solidified MS basal medium or with 0.05 or 0.1 mg/1 naphthaleneacetic acid. Hardening and survival of tissue culture plantlets was 95% under greenhouse conditions.Abbreviations
BAP
6-Benzylaminopurine
- GA3
Gibberellic acid
- MS
Murashige and Skoog medium
-
NAA
-Napthaleneacetic acid 相似文献
35.
Acetyl esterase production by Termitomyces clypeatus 总被引:1,自引:0,他引:1
A. Mukhopadhyay P.P. Hazra T. Sengupta A.K. Ghosh S. Sengupta 《Biotechnology letters》1997,19(2):159-162
Production of acetyl esterase by Termitomyces clypeatus was stimulated by xylan, cellulose, arabinose and arabinose-containing polysaccharides in the growth medium. The culture filtrate was equally active with p-nitrophenyl acetate and acetyl xylan. Acetyl xylan was completely deacetylated by the enzyme. Activity was optimum at pH 6.5 and at 50¡C. The Km values for p-nitrophenyl acetate and acetyl xylan were 0.83 mM and 0.38% (w/v) with Vm of 48 and 55 mmole acetate produced/min.mg protein, respectively. 相似文献
36.
The presence of two distinct 8-oxoguanine repair enzymes in human cells: their potential complementary roles in preventing mutation. 总被引:14,自引:4,他引:10
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
8-Oxoguanine (8-oxoG), induced by reactive oxygen species (ROS) and ionizing radiation, is arguably the most important mutagenic lesion in DNA. This oxidized base, because of its mispairing with A, induces GC-->TA transversion mutations often observed spontaneously in tumor cells. The human cDNA encoding the repair enzyme 8-oxoG-DNA glycosylase (OGG-1) has recently been cloned, however, its activity was never detected in cells. Here we show that the apparent lack of this activity could be due to the presence of an 8-oxoG-specific DNA binding protein. Moreover, we demonstrate the presence of two antigenically distinct OGG activities with an identical reaction mechanism in human cell (HeLa) extracts. The 38 kDa OGG-1, identical to the cloned enzyme, cleaves 8-oxoG when paired with cytosine, thymine and guanine but not adenine in DNA. In contrast, the newly discovered 36 kDa OGG-2 prefers 8-oxoG paired with G and A. We propose that OGG-1 and OGG-2 have distinct antimutagenic functions in vivo . OGG-1 prevents mutation by removing 8-oxoG formed in DNA in situ and paired with C, while OGG-2 removes 8-oxoG that is incorporated opposite A in DNA from ROS-induced 8-oxodGTP. We predict that OGG-2 specifically removes such 8-oxoG residues only from the nascent strand, possibly by utilizing the same mechanism as the DNA mismatch repair pathway. 相似文献
37.
Early steps in the DNA base excision/single-strand interruption repair pathway in mammalian cells 总被引:1,自引:0,他引:1
Base excision repair (BER) is an evolutionarily conserved process for maintaining genomic integrity by eliminating several dozen damaged (oxidized or aikylated) or inappropriate bases that are generated endogenously or induced by genotoxicants, predominantly, reactive oxygen species (ROS). BER involves 4-5 steps starting with base excision by a DNA glycosylase, followed by a common pathway usually involving an AP-endonuclease (APE) to generate 3' OH terminus at the damage site, followed by repair synthesis with a DNA polymerase and nick sealing by a DNA iigase. This pathway is also responsible for repairing DNA single-strand breaks with blocked termini directly generated by ROS. Nearly all glycosylases, far fewer than their substrate lesions particularly for oxidized bases, have broad and overlapping substrate range, and could serve as back-up enzymes in vivo. In contrast, mammalian cells encode only one APE, APEI, unlike two APEs in lower organisms. In spite of overall similarity, BER with distinct subpathways in the mammals is more complex than in E. coli. The glycosylases form complexes with downstream proteins to carry out efficient repair via distinct subpathways one of which, responsible for repair of strand breaks with 3' phosphate termini generated by the NEIL family glycosylases or by ROS, requires the phosphatase activity of polynucleotide kinase instead of APE1. Different complexes may utilize distinct DNA polymerases and iigases. Mammalian glycosylases have nonconserved extensions at one of the termini, dispensable for enzymatic activity but needed for interaction with other BER and non-BER proteins for complex formation and organeile targeting. The mammalian enzymes are sometimes covalently modified which may affect activity and complex formation. The focus of this review is on the early steps in mammalian BER for oxidized damage. 相似文献
38.
Priyankar Paira Abhijit Hazra Shrabanti Kumar Rupankar Paira Krishnendu B. Sahu Subhendu Naskar Pritam saha Shyamal Mondal Arindam Maity Sukdeb Banerjee Nirup B. Mondal 《Bioorganic & medicinal chemistry letters》2009,19(16):4786-4789
Syntheses of 3,3-diheteroaromatic oxindole derivatives has been achieved by coupling indole-2,3-dione (isatin) with differently substituted indoles and pyrrole in presence of I2 in i-PrOH. The in vitro spermicidal potentials and the mode of spermicidal action of the synthesized analogues were evaluated and the derivative, 3,3-bis (5-methoxy-1H-indol-3-yl) indolin-2-one (3d) exhibited most significant activity. 相似文献
39.
Ishani Deb Priyankar Paira Abhijit Hazra Sukdeb Banerjee Pradip Kumar Dutta Nirup Bikash Mondal Sumantra Das 《Bioorganic & medicinal chemistry》2009,17(16):5782-5790
Based on an established 3D pharmacophore, a series of quinoline derivatives were synthesized. The opioidergic properties of these compounds were determined by a competitive binding assay using 125I-Dynorphine, 3H-DAMGO and 125I-DADLE for κ, μ, and δ receptors, respectively. Results showed varying degree of activities of the compounds to κ and μ opioid receptors with negligible interactions at the δ receptor. The compound, S4 was the most successful in inhibiting the two most prominent quantitative features of naloxone precipitated withdrawal symptoms - stereotyped jumping and body weight loss. Determination of IC50 of S4 revealed a greater affinity towards μ compared to κ receptor. In conclusion, quinoline derivatives of S4 like structure offer potential tool for treatment of narcotic addictions. 相似文献
40.
Balasubramanian Radhakrishnan Radha Prasanna Pranita Jaiswal Saswati Nayak Prem Dureja 《Biologia》2009,64(5):881-889
An investigation was undertaken to evaluate a set of cyanobacterial strains in terms of production of biocidal compounds exhibiting
allelochemical and fungicidal properties. Two cyanobacterial strains — Anabaena sp. and Calothrix sp. were selected for further investigation, on the basis of their larger inhibition zones on the lawn of Synechocystis and Synechococcus sp. and two phytopathogenic fungi — Rhizoctonia bataticola and Pythium debaryanum. The diameter of the inhibition zone was largest when extracellular filtrates of the two cultures incubated at high light
intensity (90–100 μmol photons m−2 s−1) and temperature (40 ± 2 °C) or grown in medium containing two-folds higher P (1.4 mg/L, as compared to 0.7 mg/L in BG 11
medium) were taken. A pH of 8 was the most optimal for both strains, in terms of growth and biocidal activity. Partial purification
of ethyl acetate extract using TLC, followed by GLC revealed a single peak. This study highlights the importance of environmental
factors in aggravating or reducing the toxic effects of these harmful cyanobacteria and their potential as a biocontrol agent. 相似文献