全文获取类型
收费全文 | 445篇 |
免费 | 28篇 |
出版年
2023年 | 6篇 |
2022年 | 13篇 |
2021年 | 18篇 |
2020年 | 20篇 |
2019年 | 50篇 |
2018年 | 23篇 |
2017年 | 19篇 |
2016年 | 19篇 |
2015年 | 20篇 |
2014年 | 36篇 |
2013年 | 40篇 |
2012年 | 39篇 |
2011年 | 30篇 |
2010年 | 8篇 |
2009年 | 12篇 |
2008年 | 13篇 |
2007年 | 21篇 |
2006年 | 13篇 |
2005年 | 5篇 |
2004年 | 12篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1966年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1959年 | 1篇 |
1955年 | 1篇 |
1953年 | 1篇 |
排序方式: 共有473条查询结果,搜索用时 78 毫秒
41.
Yousefi Fatemeh Najafi Hadi Behmanesh Mehrdad Soltani Bahram M. 《Molecular biology reports》2022,49(5):3377-3387
Molecular Biology Reports - Aberrant activation of the Wnt signaling pathway is observed in most colorectal cancers (CRC). OCC-1D is a splice variant of OCC-1 gene which is considered as a long... 相似文献
42.
43.
44.
Moghaddam AM Roudier F Seifert M Bérard C Magniette ML Ashtiyani RK Houben A Colot V Mette MF 《The Plant journal : for cell and molecular biology》2011,67(4):691-700
Plant genomes are earmarked with defined patterns of chromatin marks. Little is known about the stability of these epigenomes when related, but distinct genomes are brought together by intra‐species hybridization. Arabidopsis thaliana accessions and their reciprocal hybrids were used as a model system to investigate the dynamics of histone modification patterns. The genome‐wide distribution of histone modifications H3K4me2 and H3K27me3 in the inbred parental accessions Col‐0, C24 and Cvi and their hybrid offspring was compared by chromatin immunoprecipitation in combination with genome tiling array hybridization. The analysis revealed that, in addition to DNA sequence polymorphisms, chromatin modification variations exist among accessions of A. thaliana. The range of these variations was higher for H3K27me3 (typically a repressive mark) than for H3K4me2 (typically an active mark). H3K4me2 and H3K27me3 were rather stable in response to intra‐species hybridization, with mainly additive inheritance in hybrid offspring. In conclusion, intra‐species hybridization does not result in gross changes to chromatin modifications. 相似文献
45.
Low E Kim B Francavilla C Shiau TP Turtle ED O'Mahony DJ Alvarez N Houchin A Xu P Zuck M Celeri C Anderson MB Najafi RR Jain RK 《Bioorganic & medicinal chemistry letters》2011,21(12):3682-3685
Structure stability/activity relationships (SXR) of a new class of N,N-dichloroamine compounds were explored to improve antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans while maintaining aqueous solution stability. This study identified a new class of solution-stable and topical antimicrobial agents. These agents are sulfone-stabilized and possess either a quaternary ammonium or sulfonate appendages as a water solubilizing group. Several unique challenges were confronted in the synthesis of these novel compounds which are highlighted in the discussion. 相似文献
46.
Peyman?Norouzi Mohammad?A.?MalboobiEmail author Katayoun?Zamani Hahman?Yazdi-Samadi 《In vitro cellular & developmental biology. Plant》2005,41(1):11-16
Summary Despite intensive efforts, a reproducible and reliable method for transformation of sugarbeet plants is still lacking. Having
examined several explants, we found that cells around the main vein of leaves of plantlets reared from tissue-cultured apical
meristems are sufficiently competent for transformation and subsequent regeneration. A transformation protocol was designed
by evaluating alterations in several parameters such as plant genotype, Agrobacterium strain, antibiotics, darkness and duration of co-culture period. An average transformation rate of 6.2% transformed shoots
per explant was achieved as judged by Southern blotting. Consistent inactivation of reporter genes was correlated to multiple
copies of transgenes present in some transformants. The necessary steps for rooting and planting of transformed shoots were
also established. 相似文献
47.
Sonboli A Salehi P Kanani MR Ebrahimi SN 《Zeitschrift für Naturforschung. C, Journal of biosciences》2005,60(7-8):534-538
The in vitro antibacterial and antioxidant activity of the essential oil and its two main components of Grammosciadium scabridum Boiss. (Apiaceae) growing wild in Iran, as well as the composition of its essential oil were studied. A total of 19 compounds representing 99.9% of the oil has been identified. Gamma-Terpinene (73.5%), p-cymene (14.2%) and (E)-beta-farnesene (5.3%) were characterized as the main components. The oil showed remarkable activity against three Gram-negative and four Gram-positive test bacteria, with minimal inhibitory concentration (MIC) values ranging from 0.31 to 10.00 mg/ml. The oil and its two main components were also subjected to screening for their possible antioxidant activity by using the 2,2-diphenyl-l-picrylhydrazyl (DPPH) assay. The free radical scavenging capacity of the oil was determined with an IC50 value of 6.6 mg/ml. 相似文献
48.
A series of 1-ns MD simulations were performed on the scorpion toxin Lqh III in native and disulfide bond broken states. The removal of disulfide bonds has caused hydrogen bond network alteration in the five-residue turn, the long loop, the alpha-helix, the loop connecting strands II and III, and the C-terminal region. In addition and more importantly, it has influenced the amplitude of the fluctuations of five-residue turn, loops, and C-terminal region with a minor effect on the fluctuations of the cysteines in the broken bond sites. These findings suggest that disulfide bonds are not the most important factors in rigidifying their own locations, while they have more important effects at a global scale. Furthermore, our results reveal that disulfide bonds have considerable influence on the functionally important essential modes of motions and the correlations between the motions of the binding site residues. Therefore, we can conclude that disulfide bonds have a crucial role in modulating the function via adjusting the dynamics of scorpion toxin molecules. Although this conclusion cannot be generalized to all peptides and proteins, it demonstrates the importance of more investigations on this aspect of disulfide bond efficacy. 相似文献
49.
Composition and antimicrobial activity of the essential oil of Dicyclophora persica Boiss. from Iran
Salehi P Sonboli A Mohammadi F 《Zeitschrift für Naturforschung. C, Journal of biosciences》2006,61(5-6):315-318
The chemical composition of the essential oil of Dicyclophora persica Boiss. was identified by GC and GC-MS analysis. The analysis of the oil resulted in the identification of forty-five components constituting 98.6% of the total oil. The main constituents were a-pinene (31.5%), (Z)-beta-ocimene (23.3%), p-cymene (6.7%) and (E)-beta-ocimene (5.4%). The antimicrobial activity of the oil was tested by the disk diffusion method against four Gram-positive (Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis) and three Gram-negative (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) bacteria together with a fungus (Aspergillus niger). The oil showed strong inhibition activity toward all the tested microorganisms except for Pseudomonas aeruginosa. 相似文献
50.
A Gdalyahu E Tring PO Polack R Gruver P Golshani MS Fanselow AJ Silva JT Trachtenberg 《Neuron》2012,75(1):121-132
Several models of associative learning predict that stimulus processing changes during association formation. How associative learning reconfigures neural circuits in primary sensory cortex to "learn" associative attributes of a stimulus remains unknown. Using 2-photon in vivo calcium imaging to measure responses of networks of neurons in primary somatosensory cortex, we discovered that associative fear learning, in which whisker stimulation is paired with foot shock, enhances sparse population coding and robustness of the conditional stimulus, yet decreases total network activity. Fewer cortical neurons responded to stimulation of the trained whisker than in controls, yet their response strength was enhanced. These responses were not observed in mice exposed to a nonassociative learning procedure. Our results define how the cortical representation of a sensory stimulus is shaped by associative fear learning. These changes are proposed to enhance efficient sensory processing after associative learning. 相似文献