全文获取类型
收费全文 | 240篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
260篇 |
出版年
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 9篇 |
2013年 | 15篇 |
2012年 | 19篇 |
2011年 | 20篇 |
2010年 | 18篇 |
2009年 | 8篇 |
2008年 | 9篇 |
2007年 | 15篇 |
2006年 | 17篇 |
2005年 | 13篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 9篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 8篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1975年 | 3篇 |
1970年 | 1篇 |
排序方式: 共有260条查询结果,搜索用时 0 毫秒
191.
Masamitsu Negishi Somsakul P. Wongpalee Sukumar Sarkar Jonghoon Park Kyung Yong Lee Yoshiyuki Shibata Brian J. Reon Roger Abounader Yutaka Suzuki Sumio Sugano Anindya Dutta 《PloS one》2014,9(4)
Long noncoding RNAs (lncRNAs) have emerged as a major regulator of cell physiology, but many of which have no known function. CDKN1A/p21 is an important inhibitor of the cell-cycle, regulator of the DNA damage response and effector of the tumor suppressor p53, playing a crucial role in tumor development and prevention. In order to identify a regulator for tumor progression, we performed an siRNA screen of human lncRNAs required for cell proliferation, and identified a novel lncRNA, APTR, that acts in trans to repress the CDKN1A/p21 promoter independent of p53 to promote cell proliferation. APTR associates with the promoter of CDKN1A/p21 and this association requires a complementary-Alu sequence encoded in APTR. A different module of APTR associates with and recruits the Polycomb repressive complex 2 (PRC2) to epigenetically repress the p21 promoter. A decrease in APTR is necessary for the induction of p21 after heat stress and DNA damage by doxorubicin, and the levels of APTR and p21 are anti-correlated in human glioblastomas. Our data identify a new regulator of the cell-cycle inhibitor CDKN1A/p21 that acts as a proliferative factor in cancer cell lines and in glioblastomas and demonstrate that Alu elements present in lncRNAs can contribute to targeting regulatory lncRNAs to promoters. 相似文献
192.
Structural and functional analyses of the major outer membrane protein of Chlamydia trachomatis 下载免费PDF全文
Sun G Pal S Sarcon AK Kim S Sugawara E Nikaido H Cocco MJ Peterson EM de la Maza LM 《Journal of bacteriology》2007,189(17):6222-6235
Chlamydia trachomatis is a major pathogen throughout the world, and preventive measures have focused on the production of a vaccine using the major outer membrane protein (MOMP). Here, in elementary bodies and in preparations of the outer membrane, we identified native trimers of the MOMP. The trimers were stable under reducing conditions, although disulfide bonds appear to be present between the monomers of a trimer and between trimers. Cross-linking of the outer membrane complex demonstrated that the MOMP is most likely not in a close spatial relationship with the 60- and 12-kDa cysteine-rich proteins. Extraction of the MOMP from Chlamydia isolates under nondenaturing conditions yielded the trimeric conformation of this protein as shown by cross-linking and analysis by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis with different concentrations of acrylamide. Using circular dichroism spectroscopy, we determined that the trimers were formed mainly of beta-pleated sheet structures in detergent micelles. Using a liposomal swelling assay, the MOMP was found to have porin activity, and the size of the pore was estimated to be approximately 2 nm in diameter. The trimers were found to be stable in SDS at temperatures ranging from 4 to 37 degrees C and over a pH range of 5.0 to 8.0. In addition, the trimers of MOMP were found to be resistant to digestion with trypsin. In conclusion, these results show that the native conformation of the MOMP of C. trachomatis is a trimer with predominantly a beta-sheet structure and porin function. 相似文献
193.
I L Karle J L Flippen-Anderson M Sukumar P Balaram 《International journal of peptide and protein research》1990,35(6):518-526
An apolar helical decapeptide with different end groups, Boc- or Ac-, crystallizes in a completely parallel fashion for the Boc-analog and in an antiparallel fashion for the Ac-analog. In both crystals, the packing motif consists of rows of parallel molecules. In the Boc-crystals, adjacent rows assemble with the helix axes pointed in the same direction. In the Ac-crystals, adjacent rows assemble with the helix axes pointed in opposite directions. The conformations of the molecules in both crystals are quite similar, predominantly alpha-helical, except for the tryptophanyl side chain where chi 1 congruent to 60 degrees in the Boc- analog and congruent to 180 degrees in the Ac-analog. As a result, there is one lateral hydrogen bond between helices, N(1 epsilon)...O(7), in the Ac-analog. The structures do not provide a ready rationalization of packing preference in terms of side-chain interactions and do not support a major role for helix dipole interactions in determining helix orientation in crystals. The crystal parameters are as follow. Boc-analog: C60H97N11O13.C3H7OH, space group Pl with a = 10.250(3) A, b = 12.451(4) A, c = 15.077(6) A, alpha = 96.55(3) degrees, beta = 92.31(3) degrees, gamma = 106.37(3) degrees, Z = 1, R = 5.5% for 5581 data ([F] greater than 3.0 sigma(F)), resolution 0.89 A. Ac-analog: C57H91N11O12, space group P2(1) with a = 9.965(1) A, b = 19.707(3) A, c = 16.648(3) A, beta = 94.08(1), Z = 2, R = 7.2% for 2530 data ([F] greater than 3.0 sigma(F)), resolution 1.00 A. 相似文献
194.
Multiplex polymerase chain reaction-based assay for the specific detection of toxin-producing Vibrio cholerae in fish and fishery products 总被引:1,自引:0,他引:1
Jeyasekaran G Raj KT Shakila RJ Thangarani AJ Sukumar D 《Applied microbiology and biotechnology》2011,90(3):1111-1118
A multiplex polymerase chain reaction (MPCR)-based assay was developed for the simultaneous detection of Vibrios using the genus-specific RNA polymerase subunit A (rpoA) gene and specific detection of toxin-producing Vibrio cholerae strains using two sets of primer based on cholera toxin subunit A (ctxA) and repeat in toxin subunit A (RtxA)-producing genes. The MPCR method developed is applicable to both the simultaneous and the two-step detection of genus Vibrio total and toxigenic V. cholerae species. This assay was specific as no amplification occurred with the other bacterial pathogens tested. The sensitivity
of the assay was tested by artificially spiking the shrimp homogenate with the toxigenic strain of V. cholerae (NICED 16582) in different dilutions. The developed MPCR assay could detect three cells of V. cholerae in 12 h pre-enrichment in APW. The proposed method is rapid, sensitive, and specific for the detection of Vibrio genus as well as toxin-producing V. cholerae strains in environmental samples. 相似文献
195.
We investigated the preventive potential of paeonol on 7,12-dimethylbenz(a)anthracene (DMBA) induced oral carcinogenesis. Oral tumors were developed in the buccal pouches of Syrian golden hamsters using topical application of 0.5% DMBA three times/week for 10 weeks. DMBA treated hamsters developed hyperplasia, dysplasia and well-differentiated squamous cell carcinoma. The animals also exhibited increased lipid oxidation, decreased antioxidant status and altered levels of detoxification agents. Paeonol treatment of DMBA treated hamsters for 14 weeks decreased tumor incidence, volume and burden Paeonol treatment also increased antioxidant activity and decreased lipid oxidation to near normal levels. Histomorphology and the expression patterns of mutant p53, cyclo-oxygenase (COX-2) and caspase-9 were investigated in the oral buccal mucosa. Paeonol exhibited protective effects against DMBA induced oral carcinogenesis owing to its antitumor, antioxidant, anti-inflammatory and apoptosis inducing properties. 相似文献
196.
197.
Osman A. Gutiérrez David M. Stelly Sukumar Saha Johnie N. Jenkins Jack C. McCarty Jr Dwaine A. Raska Brian E. Scheffler 《Molecular breeding : new strategies in plant improvement》2009,23(4):693-707
A combination of previously mapped and unmapped non-redundant SSR loci, using 381 primer pairs were chromosomally and sub-chromosomally
localized by deficiency analysis of two sets of quasi-isogenic interspecific Gossypium hirsutum L. hypoaneuploid F1 hybrids involving Gossypium barbadense L. and Gossypium tomentosum (Nuttall ex Seemann). Polymorphisms were detected for 369 SSR primer pairs. A total of 318 SSR loci were rendered deficient
by the available hypoaneuploid stocks, which included primary monosomics (2n = 51), monotelodisomics and duplication-deficient (segmental trisomic–monosomic) (2n = 52) types. Chromosomal associations were newly determined for 123 SSR loci, of which 90, 106 and 73 were polymorphic in
G. tomentosum, G. barbadense, and both sets, respectively. The deficiency tests independently confirmed the recent identifications of linkage groups (LG)
A01, A02, A03 and D08 to be chromosome (Chr)-13, Chr-8, Chr-11 and Chr-19, respectively, and collectively delimited LG D02
and D03 to Chr-21 and 24, and their homeologs to Chr-8 and 11. Segmental homeology was detected between Chr-2 and Chr-17 loci,
adding to evidence of segmental homeology between Chr-2 and 3 versus Chr-14 and 17. The 318 non-redundant SSR loci localized
in this study will enhance the construction of linkage maps and QTL identification in molecular marker assisted selection
since the confirmed and newly discovered SSR loci can serve as anchor loci for their respective chromosomes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
198.
Rashmi Chaturvedi Kushagra Bansal Yeddula Narayana Nisha Kapoor Namineni Sukumar Shambhuprasad Kotresh Togarsimalemath Nagasuma Chandra Saurabh Mishra Parthasarathi Ajitkumar Beenu Joshi Vishwa Mohan Katoch Shripad A. Patil Kithiganahalli N. Balaji 《The Journal of biological chemistry》2010,285(40):30389-30403
199.
Nicotinic receptor signaling in nonexcitable cells 总被引:6,自引:0,他引:6
The finding that neuronal nicotinic acetylcholine receptors (nAChRs) are present in non-neuronal cells both within and outside the nervous system raises some interesting issues. The mechanisms underlying receptor signaling and its downstream consequences in these cells remain to be elucidated. Factors controlling the release of acetylcholine and the extent of its diffusion are likely to be different for these cells than for traditional neuronal synapses. Recent advances on the physiologic functions of some of these cell types have provided a better insight into possible functional roles for nAChRs in nonexcitable cells. The presence of nAChRs on these cells also implies a broader scope for the actions of nicotine that needs to be considered from a clinical viewpoint. Revealing the potential physiologic roles for nAChRs on nonexcitable cells is likely to provide a more complete understanding of cholinergic signaling. 相似文献