全文获取类型
收费全文 | 530篇 |
免费 | 47篇 |
国内免费 | 49篇 |
出版年
2023年 | 11篇 |
2022年 | 8篇 |
2021年 | 36篇 |
2020年 | 17篇 |
2019年 | 30篇 |
2018年 | 20篇 |
2017年 | 16篇 |
2016年 | 40篇 |
2015年 | 39篇 |
2014年 | 45篇 |
2013年 | 45篇 |
2012年 | 60篇 |
2011年 | 48篇 |
2010年 | 23篇 |
2009年 | 23篇 |
2008年 | 26篇 |
2007年 | 23篇 |
2006年 | 18篇 |
2005年 | 25篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1991年 | 3篇 |
1988年 | 2篇 |
1986年 | 1篇 |
排序方式: 共有626条查询结果,搜索用时 15 毫秒
101.
102.
During early postnatal development, dendrites of retinal ganglion cells (RGCs) extend and branch in the inner plexiform layer to establish the adult level of stratification, pattern of branching, and coverage. Many studies have described the branching patterns, transient features, and regulatory factors of stratification of the RGCs. The rate of RGC dendritic field (DF) expansion relative to the growing retina has not been systematically investigated. In this study, we used two methods to examine the relative expansion of RGC DFs. First, we measured the size of RGC DFs and the diameters of the eyeballs at several postnatal stages. We compared the measurements with the RGC DF sizes calculated from difference of the eyeball sizes based on a linear expansion assumption. Second, we used the number of cholinergic amacrine cells (SACs) circumscribed by the DFs of RGCs at corresponding time points as an internal ruler to assess the size of DFs. We found most RGCs exhibit a phase of faster expansion relative to the retina between postnatal day 8 (P8) and P13, followed by a phase of retraction between P13 and adulthood. The morphological α cells showed the faster growing phase but not the retraction phase, whereas the morphological ON–OFF direction selective ganglion cells expanded in the same pace as the growing retina. These findings indicate different RGCs show different modes of growth, whereas most subtypes exhibit a fast expansion followed by a retraction phase to reach the adult size. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 70: 397–407, 2010 相似文献
103.
Background
Prostatitis is associated with a characteristic increase in prostatic fluid pH; however, the underlying mechanism and its physiological significance have not been elucidated.Methodology/Principal Findings
In this study a primary culture of rat prostatic epithelial cells and a rat prostatitis model were used. Here we reported the involvement of CFTR, a cAMP-activated anion channel conducting both Cl− and HCO3 −, in mediating prostate HCO3 − secretion and its possible role in bacterial killing. Upon Escherichia coli (E coli)-LPS challenge, the expression of CFTR and carbonic anhydrase II (CA II), along with several pro-inflammatory cytokines was up-regulated in the primary culture of rat prostate epithelial cells. Inhibiting CFTR function in vitro or in vivo resulted in reduced bacterial killing by prostate epithelial cells or the prostate. High HCO3 − content (>50 mM), rather than alkaline pH, was found to be responsible for bacterial killing. The direct action of HCO3 − on bacterial killing was confirmed by its ability to increase cAMP production and suppress bacterial initiation factors in E coli. The relevance of the CFTR-mediated HCO3 − secretion in humans was demonstrated by the upregulated expression of CFTR and CAII in human prostatitis tissues.Conclusions/Significance
The CFTR and its mediated HCO3 − secretion may be up-regulated in prostatitis as a host defense mechanism. 相似文献104.
105.
70%–80% of our sensory input comes from vision. Light hit the retina at the back of our eyes and the visual information is relayed into the dorsal lateral geniculate nuclei (dLGN) and primary visual cortex (V1) thereafter, constituting the image-forming visual circuit. Molecular cues are one of the key factors to guide the wiring and refinement of the image-forming visual circuit during pre- and post-embryonic stages. Distinct molecular cues are involved in different developmental stages and nucleus, suggesting diverse guidance mechanisms. In this review, we summarize molecular guidance cues throughout the image-forming visual circuit, including chiasm determination, eye-specific segregation and refinement in the dLGN, and at last the reciprocal connections between the dLGN and V1. 相似文献
106.
Tianyi Li Hongying Diao Lei Zhao Yue Xing Jichang Zhang Ning Liu Youyou Yan Xin Tian Wei Sun Bin Liu 《BMC molecular biology》2017,18(1):10
Background
Oxidative stress can induce cell injury in vascular endothelial cells, which is the initial event in the development of atherosclerosis. Although quantitative real-time polymerase chain reaction (qRT-PCR) has been widely used in gene expression studies in oxidative stress injuries, using carefully validated reference genes has not received sufficient attention in related studies. The objective of this study, therefore, was to select a set of stably expressed reference genes for use in qRT-PCR normalization in oxidative stress injuries in human umbilical vein endothelial cells (HUVECs) induced by hydrogen peroxide (H2O2).Results
Using geNorm analysis, we found that five stably expressed reference genes were sufficient for normalization in qRT-PCR analysis in HUVECs treated with H2O2. Genes with the most stable expression according to geNorm were U6, TFRC, RPLP0, GAPDH, and ACTB, and according to NormFinder were ALAS1, TFRC, U6, GAPDH, and ACTB.Conclusion
Taken together, our study demonstrated that the expression stability of reference genes may differ according to the statistical program used. U6, TFRC, RPLP0, GAPDH, and ACTB was the optimal set of reference genes for studies on gene expression performed by qRT-PCR assays in HUVECs under oxidative stress study.107.
Synthesis and application of thiol‐functionalized magnetic nanoparticles for studying interactions of epirubicin hydrochloride with bovine serum albumin by fluorescence spectrometry 下载免费PDF全文
Huixia Xiong Quanping Diao Rui Jin Daqian Song Xinghua Wang Ying Sun 《Luminescence》2017,32(2):142-148
A novel method was developed for studying the interaction between epirubicin hydrochloride (EPI) and bovine serum albumin (BSA) by fluorescence spectrometry. Fe3O4 magnetic nanoparticles (MNPs) synthesized and functionalized with thiol group were employed for the immobilization and separation of target BSA in reaction solutions. The concentrations of the non‐immobilized BSA and unbound EPI were obtained separately by fluorescence spectrometry. The binding constants (K a ) and number of binding sites (n ) of EPI with BSA were calculated. In this study, the K a value was 5.05 × 105 L mol?1, suggesting a strong binding of EPI to BSA, and the n value was 1.15. The effects of common metal ions on K a of EPI with BSA were also investigated, and the results showed there was clearly bindings between the metal ions and BSA. The precise binding sites of EPI on BSA were determined as being in site I from the competitive displacement experiments. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
108.
Jingyu Diao Rie Komura Tatsuya Sano Homer Pantua Kelly M. Storek Hiroko Inaba Haruhiko Ogawa Cameron L. Noland Yutian Peng Susan L. Gloor Donghong Yan Jing Kang Anand Kumar Katakam Michael Volny Peter Liu Nicholas N. Nickerson Wendy Sandoval Cary D. Austin Jeremy Murray Steven T. Rutherford Mike Reichelt Yiming Xu Min Xu Hayato Yanagida Junichi Nishikawa Patrick C. Reid Christian N. Cunningham Sharookh B. Kapadia 《Journal of bacteriology》2021,203(13)
109.
LysGH15, a phage endolysin, exhibits a particularly broad lytic spectrum against Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA). Sequence analysis reveals that this endolysin contains a C-terminal cell wall binding domain (SH3b), which causes
the endolysin to bind to host strains. In this study, the substrate binding affinity of the SH3b domain (LysGH15B) was evaluated.
A fusion protein of LysGH15B and green fluorescent protein (LysGH15B–GFP) were cloned and expressed in Escherichia coli. Laser scanning confocal microscopy was used to detect the fluorescence of the treated cells irradiated at different excitation
wavelengths and to determine the binding activity of LysGH15B–GFP and GFP. We found that LysGH15B–GFP not only generated green
fluorescence, but, more importantly, also displayed specific affinity to staphylococcal isolates, especially MRSA. In contrast,
the single GFP did not display any binding activity. The high affinity was attributed to the portion of LysGH15B and the binding
activity of the fusion protein was specific to staphylococci. This study provides an insight into the SH3b domain of LysGH15.
The specific binding activity may cause LysGH15B to serve as an anchoring device, and offer an alternative approach for cell
surface attachment onto staphylococci. 相似文献
110.
T. Blackstone R. Scharein B. Borgo R. Varela Y. Diao J. Arsuaga 《Journal of mathematical biology》2011,62(3):371-389
During the early phase of the cell cycle the eukaryotic genome is organized into chromosome territories. The geometry of the interface between any two chromosomes remains a matter of debate and may have important functional consequences. The Interchromosomal Network model (introduced by Branco and Pombo) proposes that territories intermingle along their periphery. In order to partially quantify this concept we here investigate the probability that two chromosomes form an unsplittable link. We use the uniform random polygon as a crude model for chromosome territories and we model the interchromosomal network as the common spatial region of two overlapping uniform random polygons. This simple model allows us to derive some rigorous mathematical results as well as to perform computer simulations easily. We find that the probability that one uniform random polygon of length n that partially overlaps a fixed polygon is bounded below by \({1-O(\frac{1}{\sqrt n})}\). We use numerical simulations to estimate the dependence of the linking probability of two uniform random polygons (of lengths n and m, respectively) on the amount of overlapping. The degree of overlapping is parametrized by a parameter \({\epsilon\in [0,1]}\) such that \({\epsilon=0}\) indicates no overlapping and \({\epsilon=1}\) indicates total overlapping. We propose that this dependence relation may be modeled as \({f(\varepsilon, m, n) =1-{\frac{a(\epsilon)}{b(\epsilon)\sqrt{mn}+c(\epsilon)}}}\). Numerical evidence shows that this model works well when \({\epsilon}\) is relatively large \({(\varepsilon \ge 0.5)}\). We then use these results to model the data published by Branco and Pombo and observe that for the amount of overlapping observed experimentally the URPs have a non-zero probability of forming an unsplittable link. 相似文献