全文获取类型
收费全文 | 249篇 |
免费 | 29篇 |
国内免费 | 4篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 9篇 |
2015年 | 18篇 |
2014年 | 14篇 |
2013年 | 11篇 |
2012年 | 27篇 |
2011年 | 15篇 |
2010年 | 15篇 |
2009年 | 6篇 |
2008年 | 21篇 |
2007年 | 11篇 |
2006年 | 9篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1966年 | 2篇 |
排序方式: 共有282条查询结果,搜索用时 15 毫秒
61.
62.
K. Rajasekaran S. C. Schank I. K. Vasil 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1986,73(1):4-10
Summary Five hundred and twenty-four plants of a triploid, sexually sterile hybrid napiergrass (Pennisetum americanum x P. purpureum; 3x=21) were regenerated from embryogenic callus cultures obtained from segments of young inflorescences. Replicated field trials were conducted for two consecutive years to compare the biomass yield, phenotype and cytology of tissue culture regenerants (TC) and vegetatively propagated (V) plants. In the first year total biomass yield of TC plants was significantly greater than V plants but there was no significant difference in the second year. TC plants had more tillers compared to V plants. V plants did not show any morphological variability. The TC population also exhibited a high degree of phenotypic stability (96%). There were 23 phenotypic variants in the TC population of 524, most of them being more dwarf and late-flowering. Detailed morphological analysis of the TC-variant plants suggests that they very likely arose from only a few variant cell lines. Cytological analysis indicated stability of the triploid status in randomly selected regenerants. Two of the morphological variants were hexaploids (6x=42). It is concluded that embryogenic callus cultures can provide useful alternative for the rapid propagation of hybrid napier-grass which is commonly propagated by cuttings. 相似文献
63.
1. 5,6-Monoepoxy-beta-carotene and 5,6:5',6'-diepoxy-beta-carotene were partially converted into the furanoid forms during passage through the rat stomach. 2. The monoepoxide was converted into vitamin A in the small intestine and showed a biological potency 21% of that of beta-carotene. Neither beta-carotene nor 5,6-monoepoxyvitamin A was formed. 3. Intraperitoneal administration of the monoepoxide led to the accumulation of the unchanged compound in the liver and other tissues. 4. The diepoxide gave no beta-carotene or vitamin A or 5,6-monoepoxyvitamin A when given orally and showed no biological potency. 5. The significance of these results with special reference to the mechanism of formation of vitamin A from beta-carotene is discussed. 相似文献
64.
K. Sreevishnupriya P. Chandrasekaran A. Senthilkumar R. Sethumadhavan V. Shanthi P. Daisy J. Nisha K. Ramanathan R. Rajasekaran 《中国科学:生命科学英文版》2012,55(12):1109-1119
In this work, the most detrimental missense mutations of aspartoacylase that cause Canavan??s disease were identified computationally and the substrate binding efficiencies of those missense mutations were analyzed. Out of 30 missense mutations, I-Mutant 2.0, SIFT and PolyPhen programs identified 22 variants that were less stable, deleterious and damaging respectively. Subsequently, modeling of these 22 variants was performed to understand the change in their conformations with respect to the native aspartoacylase by computing their root mean squared deviation (RMSD). Furthermore, the native protein and the 22 mutants were docked with the substrate NAA (N-Acetyl-Aspartic acid) to explain the substrate binding efficiencies of those detrimental missense mutations. Among the 22 mutants, the docking studies identified that 15 mutants caused lower binding affinity for NAA than the native protein. Finally, normal mode analysis determined that the loss of binding affinity of these 15 mutants was caused by altered flexibility in the amino acids that bind to NAA compared with the native protein. Thus, the present study showed that the majority of the substrate-binding amino acids in those 15 mutants displayed loss of flexibility, which could be the theoretical explanation of decreased binding affinity between the mutant aspartoacylases and NAA. 相似文献
65.
Heng B. Xie Anthony Cammarato Namakkal S. Rajasekaran Huali Zhang Jennifer A. Suggs Ho-Chen Lin Sanford I. Bernstein Ivor J. Benjamin Kent G. Golic 《PLoS genetics》2013,9(6)
Dominant mutations in the alpha-B crystallin (CryAB) gene are responsible for a number of inherited human disorders, including cardiomyopathy, skeletal muscle myopathy, and cataracts. The cellular mechanisms of disease pathology for these disorders are not well understood. Among recent advances is that the disease state can be linked to a disturbance in the oxidation/reduction environment of the cell. In a mouse model, cardiomyopathy caused by the dominant CryABR120G missense mutation was suppressed by mutation of the gene that encodes glucose 6-phosphate dehydrogenase (G6PD), one of the cell''s primary sources of reducing equivalents in the form of NADPH. Here, we report the development of a Drosophila model for cellular dysfunction caused by this CryAB mutation. With this model, we confirmed the link between G6PD and mutant CryAB pathology by finding that reduction of G6PD expression suppressed the phenotype while overexpression enhanced it. Moreover, we find that expression of mutant CryAB in the Drosophila heart impaired cardiac function and increased heart tube dimensions, similar to the effects produced in mice and humans, and that reduction of G6PD ameliorated these effects. Finally, to determine whether CryAB pathology responds generally to NADPH levels we tested mutants or RNAi-mediated knockdowns of phosphogluconate dehydrogenase (PGD), isocitrate dehydrogenase (IDH), and malic enzyme (MEN), the other major enzymatic sources of NADPH, and we found that all are capable of suppressing CryABR120G pathology, confirming the link between NADP/H metabolism and CryAB. 相似文献
66.
E Rajasekaran 《Bioinformation》2012,8(11):508-512
Carbon distribution is responsible for stability and structure of proteins. Arrangement of carbon along the protein sequence is depends on how the amino acids are organized and is guided by mRNAs. An atomic level revision is important for understanding these codes. This will ultimately help in identification of disorders and suggest mutations. For this purpose a carbon distribution analysis program has been developed. This program captures the hydrophobic / hydrophilic / disordered regions in a protein. The program gives accurate results. The calculations are precise and sensitive to single amino acid resolution. This program is to help in mutational studies leading to protein stabilisation. 相似文献
67.
Oldenlandia umbellata L., commonly known as “Indian madder”, is an ancient Indian herb valued as a source of red color dye and various medicinal
products. In this study, successful protocols have been developed for induction of somatic embryogenesis and organogenesis
in O. umbellata. Emerging young leaves, shoot apices, and stems were used as explants, grown on Murashige and Skoog (MS) media supplemented
with various auxins, including indole acetic acid, indole butyric acid, napthaleneacetic acid (NAA), and 2,4-Dichlorophenoxyacetic
acid, each at levels ranging between 0.1 and 0.5 mg/l, cytokinins, including benzyladenine (BA) and kinetin, each at concentration
ranging between 0.5 and 5 mg/l, with and without coconut milk (CM) at levels of 0.5–5%. For callus induction, NAA at 2.5 mg/l
was optimal; while, for rapid embryogenic callus induction, 0.2 mg/l NAA, 0.5 mg/l BA, and 0.1% CM induced the highest frequency
(95.86%). Shoots developed upon transfer of embryogenic calli to MS medium containing 1.5 mg/l BA, 0.3 mg/l NAA and 1% CM.
For root induction, 0.3 mg/l NAA and 1.0% CM promoted highest and earliest rooting.
C. Rajasekaran contributed equally to this work. 相似文献
68.
Basirudeen Syed Ahamed Kabeer Rajasekaran Sikhamani Sowmya Swaminathan Venkatesan Perumal Paulkumaran Paramasivam Alamelu Raja 《PloS one》2009,4(5)
Background
A rapid and specific test is urgently needed for tuberculosis (TB) diagnosis especially among human immunodeficiency virus (HIV) infected individuals. In this study, we assessed the sensitivity of Interferon gamma release assay (IGRA) in active tuberculosis patients who were positive for HIV infection and compared it with that of tuberculin skin test (TST).Methodology/Principal Findings
A total of 105 HIV-TB patients who were naïve for anti tuberculosis and anti retroviral therapy were included for this study out of which 53 (50%) were culture positive. Of 105 tested, QuantiFERON-TB Gold in-tube (QFT-G) was positive in 65% (95% CI: 56% to 74%), negative in 18% (95% CI: 11% to 25%) and indeterminate in 17% (95% CI: 10% to 24%) of patients. The sensitivity of QFT-G remained similar in pulmonary TB and extra-pulmonary TB patients. The QFT-G positivity was not affected by low CD4 count, but it often gave indeterminate results especially in individuals with CD4 count <200 cells/µl. All of the QFT-G indeterminate patients whose sputum culture were positive, showed ≤0.25 IU/ml of IFN-γ response to phytohemagglutinin (PHA). TST was performed in all the 105 patients and yielded the sensitivity of 31% (95% CI: 40% to 22%). All the TST positives were QFT-G positives. The sensitivity of TST was decreased, when CD4 cell counts declined.Conclusions/Significance
Our study shows neither QFT-G alone or in combination with TST can be used to exclude the suspicion of active TB disease. However, unlike TST, QFT-G yielded fewer false negative results even in individuals with low CD4 count. The low PHA cut-off point for indeterminate results suggested in this study (≤0.25 IU/ml) may improve the proportion of valid QFT-G results. 相似文献69.
Biofuels: opportunities and challenges in India 总被引:1,自引:0,他引:1
Mambully Chandrasekharan Gopinathan Rajasekaran Sudhakaran 《In vitro cellular & developmental biology. Plant》2009,45(3):350-371
Energy plays a vital role in the economic growth of any country. Current energy supplies in the world are unsustainable from
environmental, economic, and societal standpoints. All over the world, governments have initiated the use of alternative sources
of energy for ensuring energy security, generating employment, and mitigating CO2 emissions. Biofuels have emerged as an ideal choice to meet these requirements. Huge investments in research and subsidies
for production are the rule in most of the developed countries. India started its biofuel initiative in 2003. This initiative
differs from other nations’ in its choice of raw material for biofuel production—molasses for bioethanol and nonedible oil
for biodiesel. Cyclicality of sugar, molasses, and ethanol production resulted in a fuel ethanol program which suffered from
inconsistent production and supply. The restrictive policies, availability of molasses, and cost hampered the fuel ethanol
program. Inconsistent policies, availability of land, choice of nonnative crops, yield, and market price have been major impediments
for biodiesel implementation. However, a coherent, consistent, and committed policy with long-term vision can sustain India’s
biofuel effort. This will provide energy security, economic growth, and prosperity and ensure a higher quality of life for
India. 相似文献
70.
Mason T. MacDonald Rajasekaran R. Lada A. Robin Robinson Jeff Hoyle 《Journal of Plant Growth Regulation》2010,29(3):357-365
Seed preconditioning with Ambiol® has been shown to improve germination, growth, and drought tolerance in seedlings of many species. Attempts to understand the mode of action of Ambiol have found that seed preconditioning triggers several new proteins, which suggests that Ambiol-induced benefits may persist beyond seedlings and, perhaps, into the next generation. Seeds were preconditioned with 0 and 10 mg l?1 Ambiol to determine effects on germination, seedling growth, and yield of parent tomato plants. Seeds were collected from plants in each treatment and then sown to determine effects on germination and seedling growth in the next generation. Key parameters such as percent germination, leaf area, shoot mass, root mass, and photosynthesis were significantly improved in parents and in progeny. In addition, there was a 141% increase in tomato yield in preconditioned parents. It was concluded that Ambiol-induced benefits continue throughout plant development and into the next generation, potentially having significant horticultural and economic ramifications. 相似文献