全文获取类型
收费全文 | 1230篇 |
免费 | 95篇 |
国内免费 | 3篇 |
出版年
2023年 | 4篇 |
2022年 | 18篇 |
2021年 | 13篇 |
2020年 | 16篇 |
2019年 | 26篇 |
2018年 | 27篇 |
2017年 | 28篇 |
2016年 | 28篇 |
2015年 | 48篇 |
2014年 | 55篇 |
2013年 | 71篇 |
2012年 | 94篇 |
2011年 | 89篇 |
2010年 | 58篇 |
2009年 | 48篇 |
2008年 | 54篇 |
2007年 | 67篇 |
2006年 | 71篇 |
2005年 | 57篇 |
2004年 | 77篇 |
2003年 | 61篇 |
2002年 | 70篇 |
2001年 | 17篇 |
2000年 | 15篇 |
1999年 | 19篇 |
1998年 | 22篇 |
1997年 | 19篇 |
1996年 | 23篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 12篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 10篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1945年 | 2篇 |
排序方式: 共有1328条查询结果,搜索用时 15 毫秒
111.
Novel type of hepatitis B virus mutation: replacement mutation involving a hepatocyte nuclear factor 1 binding site tandem repeat in chronic hepatitis B virus genotype E
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Fujiwara K Tanaka Y Paulon E Orito E Sugiyama M Ito K Ueda R Mizokami M Naoumov NV 《Journal of virology》2005,79(22):14404-14410
112.
Mapping and characterization of new EST-derived microsatellites for potato (Solanum tuberosum L.) 总被引:8,自引:0,他引:8
Feingold S Lloyd J Norero N Bonierbale M Lorenzen J 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2005,111(3):456-466
Microsatellites, or simple sequence repeats (SSRs) are very useful molecular markers for a number of plant species. They are commonly used in cultivar identification, plant variety protection, as anchor markers in genetic mapping, and in marker-assisted breeding. Early development of SSRs was hampered by the high cost of library screening and clone sequencing. Currently, large public SSR datasets exist for many crop species, but the number of publicly available, mapped SSRs for potato is relatively low (~100). We have utilized a database mining approach to identify SSR-containing sequences in The Institute For Genomic Research Potato Gene Index database (), focusing on sequences with size polymorphisms present in this dataset. Ninety-four primer pairs flanking SSR sequences were synthesized and used to amplify potato DNA. This study rendered 61 useful SSRs that were located in pre-existing genetic maps, fingerprinted in a set of 30 cultivars from South America, North America, and Europe or a combination thereof. The high proportion of success (65%) of expressed sequence tag-derived SSRs obtained in this work validates the use of transcribed sequences as a source of markers. These markers will be useful for genetic mapping, taxonomic studies, marker-assisted selection, and cultivar identification. 相似文献
113.
114.
In proteins and peptides, the vast majority of peptide bonds occurs in trans conformation, but a considerable fraction (about 5%) of X-Pro bonds adopts the cis conformation. Here we study the conservation of cis prolyl residues in evolutionary related proteins. We find that overall, in contrast to local, protein sequence similarity is a clear indicator for the conformation of prolyl residues. We observe that cis prolyl residues are more often conserved than trans prolyl residues, and both are more conserved than the surrounding amino acids, which show the same extent of conservation as the whole protein. The pattern of amino acid exchanges differs between cis and trans prolyl residues. Also, the cis prolyl bond is maintained in proteins with sequence identity as low as 20%. This finding emphasizes the importance of cis peptide bonds in protein structure and function. 相似文献
115.
116.
A new off-resonance spin-lock experiment to record relaxation dispersion profiles of amide protons is presented. The sensitivity-enhanced
HSQC-type sequence is designed to minimize the interference from cross-relaxation effects and ensure that the dispersion profiles
in the absence of μs-ms time-scale dynamics are flat. Toward this end (i) the proton background is eliminated by sample deuteration (Ishima et al., 1998), (ii) 1H spin lock is applied to two-spin modes 2(HxSin ϑ + HzCos ϑ)
Nz, and (iii) the tilt angle ϑ ≈ 35° is maintained throughout the series of measurements (Desvaux et al. Mol. Phys., 86 (1995) 1059). The relaxation dispersion profiles recorded in this manner sample a wide range of effective rf field strengths
(up to and in excess of 20 kHz) which makes them particularly suitable for studies of motions on the time scale ≤100 μs. The
new experiment has been tested on the Ca2+-loaded regulatory domain of cardiac troponin C. Many residues show pronounced dispersions with remarkably similar correlation
times of 30 μs. Furthermore, these residues are localized in the regions that have been previously implicated in conformational
changes (Spyracopoulos et al. Biochemistry, 36 (1997) 12138)
Electronic supplementary material Electronic supplementary material is available for this article at
and accessible for authorised users. 相似文献
117.
Malakhova L Bezlepkin VG Antipova V Ushakova T Fomenko L Sirota N Gaziev AI 《Cellular & molecular biology letters》2005,10(4):721-732
Changes in the number of mitochondrial DNA (mtDNA) copies in the brain and spleen tissues of gamma-irradiated (3 Gy) mice were studied by comparative analysis of the long-extension PCR products of mtDNA (15.9 kb) and a fragment of the cluster nuclear beta-globin gene (8.7 kb) amplified simultaneously in one and the same test-tube within total DNA. The analysis showed that, compared to the nuclear beta-globin gene, an increase in mtDNA copy number (polyploidization) took place in the brain and spleen cells of mice exposed to gamma-radiation. This data led to the suggestion that the major mechanism for maintenance of the mitochondrial genome, which is constantly damaged by endogenous ROS and easily affected by ionizing radiation or other exogenous factors, is the induction of synthesis of new mtDNA copies on intact or little affected mtDNA templates because the repair systems in the mitochondria function at a low level of efficiency. 相似文献
118.
Lorenzen JA Bonacci BB Palmer RE Wells C Zhang J Haber DA Goldstein AM Mayer AN 《Gene expression patterns : GEP》2005,6(1):45-56
Intestinal development and homeostasis rely on the coordination of proliferation and differentiation of the epithelium. To better understand this process, we are studying Rbm19, a gene expressed in the gut epithelium that is essential for intestinal morphogenesis and differentiation in the zebrafish (Development 130, 3917). Here we analyzed the expression of Rbm19 in several biological contexts that feature proliferation/differentiation cell fate decisions. In the undifferentiated embryonic gut tube, Rbm19 is expressed throughout the epithelium, but then becomes localized to the crypts of Lieberkühn of the adult intestine. Consistent with its expression in adult crypt/progenitor cells, expression is widespread in human colorectal carcinomas and dividing Caco-2 cells. Its expression in Caco-2 cells recapitulates the in vivo pattern, declining when the cells undergo confluence-induced arrest and differentiation. Rbm19 protein localizes to the nucleolus during interphase and to the perichromosomal sheath during mitosis, in accordance with the pattern described for other nucleolar proteins implicated in ribosome biogenesis. Interestingly, the loss of nucleolar rbm19, nucleolin/C23, and nucleophosmin/B23 in confluent Caco-2 cells did not signify loss of nucleoli as detected by electron microscopy. Taken together, these data point to the nucleolus as a possible locus for regulating the proliferation/differentiation cell fate decision in the intestinal epithelium. 相似文献
119.
Kobrinsky E Tiwari S Maltsev VA Harry JB Lakatta E Abernethy DR Soldatov NM 《The Journal of biological chemistry》2005,280(13):12474-12485
Voltage-gated Ca(v)1.2 channels are composed of the pore-forming alpha1C and auxiliary beta and alpha2delta subunits. Voltage-dependent conformational rearrangements of the alpha1C subunit C-tail have been implicated in Ca2+ signal transduction. In contrast, the alpha1C N-tail demonstrates limited voltage-gated mobility. We have asked whether these properties are critical for the channel function. Here we report that transient anchoring of the alpha1C subunit C-tail in the plasma membrane inhibits Ca2+-dependent and slow voltage-dependent inactivation. Both alpha2delta and beta subunits remain essential for the functional channel. In contrast, if alpha1C subunits with are expressed alpha2delta but in the absence of a beta subunit, plasma membrane anchoring of the alpha1C N terminus or its deletion inhibit both voltage- and Ca2+-dependent inactivation of the current. The following findings all corroborate the importance of the alpha1C N-tail/beta interaction: (i) co-expression of beta restores inactivation properties, (ii) release of the alpha1C N terminus inhibits the beta-deficient channel, and (iii) voltage-gated mobility of the alpha1C N-tail vis a vis the plasma membrane is increased in the beta-deficient (silent) channel. Together, these data argue that both the alpha1C N- and C-tails have important but different roles in the voltage- and Ca2+-dependent inactivation, as well as beta subunit modulation of the channel. The alpha1C N-tail may have a role in the channel trafficking and is a target of the beta subunit modulation. The beta subunit facilitates voltage gating by competing with the N-tail and constraining its voltage-dependent rearrangements. Thus, cross-talk between the alpha1C C and N termini, beta subunit, and the cytoplasmic pore region confers the multifactorial regulation of Ca(v)1.2 channels. 相似文献
120.