全文获取类型
收费全文 | 217篇 |
免费 | 8篇 |
国内免费 | 1篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 7篇 |
2012年 | 14篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 12篇 |
2008年 | 7篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 10篇 |
2004年 | 4篇 |
2003年 | 13篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1966年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有226条查询结果,搜索用时 265 毫秒
71.
Christoph Klingner Anoop V. Cherian Johannes Fels Philipp M. Diesinger Roland Aufschnaiter Nicola Maghelli Thomas Keil Gisela Beck Iva M. Toli?-N?rrelykke Mark Bathe Roland Wedlich-Soldner 《The Journal of cell biology》2014,207(1):107-121
Although cortical actin plays an important role in cellular mechanics and morphogenesis, there is surprisingly little information on cortex organization at the apical surface of cells. In this paper, we characterize organization and dynamics of microvilli (MV) and a previously unappreciated actomyosin network at the apical surface of Madin–Darby canine kidney cells. In contrast to short and static MV in confluent cells, the apical surfaces of nonconfluent epithelial cells (ECs) form highly dynamic protrusions, which are often oriented along the plane of the membrane. These dynamic MV exhibit complex and spatially correlated reorganization, which is dependent on myosin II activity. Surprisingly, myosin II is organized into an extensive network of filaments spanning the entire apical membrane in nonconfluent ECs. Dynamic MV, myosin filaments, and their associated actin filaments form an interconnected, prestressed network. Interestingly, this network regulates lateral mobility of apical membrane probes such as integrins or epidermal growth factor receptors, suggesting that coordinated actomyosin dynamics contributes to apical cell membrane organization. 相似文献
72.
Background
Digital polymerase chain reaction (dPCR) is an increasingly popular technology for detecting and quantifying target nucleic acids. Its advertised strength is high precision absolute quantification without needing reference curves. The standard data analytic approach follows a seemingly straightforward theoretical framework but ignores sources of variation in the data generating process. These stem from both technical and biological factors, where we distinguish features that are 1) hard-wired in the equipment, 2) user-dependent and 3) provided by manufacturers but may be adapted by the user. The impact of the corresponding variance components on the accuracy and precision of target concentration estimators presented in the literature is studied through simulation.Results
We reveal how system-specific technical factors influence accuracy as well as precision of concentration estimates. We find that a well-chosen sample dilution level and modifiable settings such as the fluorescence cut-off for target copy detection have a substantial impact on reliability and can be adapted to the sample analysed in ways that matter. User-dependent technical variation, including pipette inaccuracy and specific sources of sample heterogeneity, leads to a steep increase in uncertainty of estimated concentrations. Users can discover this through replicate experiments and derived variance estimation. Finally, the detection performance can be improved by optimizing the fluorescence intensity cut point as suboptimal thresholds reduce the accuracy of concentration estimates considerably.Conclusions
Like any other technology, dPCR is subject to variation induced by natural perturbations, systematic settings as well as user-dependent protocols. Corresponding uncertainty may be controlled with an adapted experimental design. Our findings point to modifiable key sources of uncertainty that form an important starting point for the development of guidelines on dPCR design and data analysis with correct precision bounds. Besides clever choices of sample dilution levels, experiment-specific tuning of machine settings can greatly improve results. Well-chosen data-driven fluorescence intensity thresholds in particular result in major improvements in target presence detection. We call on manufacturers to provide sufficiently detailed output data that allows users to maximize the potential of the method in their setting and obtain high precision and accuracy for their experiments.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2105-15-283) contains supplementary material, which is available to authorized users. 相似文献73.
Y Deng J Zhao D Sakurai KM Kaufman JC Edberg RP Kimberly DL Kamen GS Gilkeson CO Jacob RH Scofield CD Langefeld JA Kelly ME Alarcón-Riquelme BIOLUPUS GENLES Networks JB Harley TJ Vyse BI Freedman PM Gaffney KM Sivils JA James TB Niewold RM Cantor W Chen BH Hahn EE Brown PROFILE BP Tsao 《Arthritis research & therapy》2012,14(Z3):A5
74.
75.
76.
Shen W Fakhoury S Donner G Henry K Lee J Zhang H Cohen J Warner R Saeed B Cherian S Tahir S Kovar P Bauch J Ng SC Marsh K Sham H Rosenberg S 《Bioorganic & medicinal chemistry letters》1999,9(5):703-708
Synthesis and biological evaluation of heteroarenes as reduced cysteine replacements are described. Of the heteroaryl groups examined with respect to FT inhibitor FTI-276 (1), pyridyl was the replacement found to be most effective. Substitutions at C4 of the pyridyl moiety did not affect the in vitro activity. Compound 9a was found to have moderate in vivo bioavailability. 相似文献
77.
Intermittent administration stimulates bone formation, whereas sustained elevation of parathyroid hormone (PTH) as in hyperparathyroidism stimulates bone resorption. Even though PTH(1-34) is the only anabolic agent clinically approved for the treatment of osteoporosis, the molecular mechanism whereby PTH mediates these opposing effects depending on timing of administration is not well understood. In this study, we sought to determine the involvement of gap junctions and hemichannels, and the protein that forms them, connexin 43 (Cx43), in the effect of PTH(1-34) on osteoblast mineralization. The osteoblast-like cell line MLO-A5 that rapidly mineralizes in culture was used. Intermittent PTH enhances mineralization, whereas continuous PTH inhibits this process. The mineralization was significantly inhibited by 18 beta-glycyrrhetinic acid, an inhibitor known to block gap junctions and hemichannels. When the cells were treated with PTH(1-34), gap junctional coupling was increased; however, the degree of stimulation was similar between intermittent and continuous treatment. The permeabilization to dye was not detected under various intermittent or continuous PTH treatments. On the other hand, the overall level of Cx43 protein increased in response to continuous PTH treatment. In contrast, when the cells were subjected to intermittent treatment overall level of Cx43 was unchanged, but there was an increase of connexons associated with an increase in Cx43 expression on the cell surface. Our results suggest that Cx43 overall expression, connexon formation and cell surface expression are differentially regulated by intermittent and continuous PTH(1-34), implying the involvement of Cx43 and Cx43-forming channels in mediating the effects of PTH on bone formation. 相似文献
78.
79.
Antigenic drift and shift involving the surface proteins of Influenza virus gave rise to new strains that caused epidemics affecting millions of people worldwide over the last hundred years. Variations in the membrane proteins like Hemagglutinin (HA) and Neuraminidase (NA) necessitates new vaccine strains to be updated frequently and poses challenge to effective vaccine design. Though the HA protein, the primary target of the human immune system, has been well studied, reports on the antigenic variability in the other membrane protein NA are sparse. In this paper we investigate the molecular basis of antigenic drift in the NA protein of the Influenza A/H3N2 vaccine strains between 1968 and 2009 and proceed to establish correlation between antigenic drift and antigen-antibody interactions. Sequence alignments and phylogenetic analyses were carried out and the antigenic variability was evaluated in terms of antigenic distance. To study the effects of antigenic drift on the protein structures, 3D structure of NA from various strains were predicted. Also, rigid body docking protocol has been used to study the interactions between these NA proteins and antibody Mem5, a 1998 antibody. 相似文献
80.
A mouse genomic clone containing a lactate dehydrogenase-A (LDH-A)
processed pseudogene and a B1 repetitive element was isolated, and a
nucleotide sequence of approximately 3 kb was determined. The pseudogene
and B1 element are flanked by perfect 13-bp repeats, and the B1 sequence
starts at 14 nucleotides 3' to the presumptive polyadenylation signal of
the pseudogene. The nucleotide sequences of the LDH-A genes and processed
pseudogenes from mouse, rat, and human were compared, and a phylogenetic
tree was constructed. The rate and pattern of nucleotide substitutions in
the LDH-A pseudogenes are similar to previously reported results (Li et al.
1984). The average rate of nucleotide substitutions in the LDH-A
pseudogenes is 4.3 X 10(- 9)/site/year. The substitutions of C----T and
G----A are most frequent, and A----G substitutions are relatively high. The
rate of synonymous substitutions in the LDH-A genes is 5.3 X 10(-9), which
is not significantly higher than the average rate of 4.7 X 10(-9) for 35
mammalian genes. The rate of nonsynonymous substitutions in the LDH-A genes
is 0.20 X 10(-9), which is considerably lower than the average rate of 0.88
X 10(-9) for 35 mammalian genes. Thus, the mammalian LDH-A gene appears to
be highly conserved in evolution.
相似文献