首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   138篇
  免费   3篇
  2023年   2篇
  2022年   5篇
  2021年   13篇
  2020年   3篇
  2019年   16篇
  2018年   6篇
  2017年   3篇
  2016年   6篇
  2015年   5篇
  2014年   9篇
  2013年   13篇
  2012年   11篇
  2011年   10篇
  2010年   6篇
  2009年   5篇
  2008年   3篇
  2007年   6篇
  2006年   5篇
  2005年   2篇
  2004年   6篇
  2003年   3篇
  1998年   1篇
  1994年   1篇
  1985年   1篇
排序方式: 共有141条查询结果,搜索用时 562 毫秒
81.
Recently, it has been revealed that estrogen-related reproductive factors are linked with some early gene expression lesions associated with malignancy in clinically healthy breasts. Accordingly, the aim of the current study was to evaluate the association of expression levels of estrogen-related long noncoding RNAs (lncRNAs) upstream Eleanor (u-Eleanor) and HOX antisense intergenic RNA (HOTAIR) with the different patterns of reproductive factors in breast tissue of healthy women. The subjects of this study were 98 cancer-free women who had undergone cosmetic mammoplasty. The expression levels of u-Eleanor and HOTAIR were measured using quantitative real-time polymerase chain reaction. The results of the current study showed that the women without a history of breastfeeding had a high-level expression of u-Eleanor compared with the women with a breastfeeding duration greater than 6 to 24 months (P = 0.03) as well as the women with a breastfeeding duration of more than 24 months (P = 0.005). Furthermore, a higher expression of u-Eleanor was found in the women with a short breastfeeding duration for 1 to 6 months than that in the women with a breastfeeding duration of greater than 24 months (P = 0.02). In the same way, the results of correlation test (r = −0.258; P = 0.036) and multivariate regression model (β = −0.321; P = 0.023) are indicative of a significant relationship of elevated expression of u-Eleanor with decreasing breastfeeding duration in the women. These findings could be important to identify the molecular mechanisms behind the relationship between a lack or short duration of the breastfeeding and the risk of breast cancer, which has previously been reported by epidemiological studies.  相似文献   
82.

Aims

Disturbance of mitochondrial function significantly contributes to the myocardial injury that occurs during reperfusion. Increasing evidence suggests a role of intra-mitochondrial cyclic AMP (cAMP) signaling in promoting respiration and ATP synthesis. Mitochondrial levels of cAMP are controlled by type 10 soluble adenylyl cyclase (sAC) and phosphodiesterase 2 (PDE2), however their role in the reperfusion-induced injury remains unknown. Here we aimed to examine whether sAC may support cardiomyocyte survival during reperfusion.

Methods and results

Adult rat cardiomyocytes or rat cardiac H9C2 cells were subjected to metabolic inhibition and recovery as a model of simulated ischemia and reperfusion. Cytosolic Ca2+, pH, mitochondrial cAMP (live-cell imaging), and cell viability were analyzed during a 15-min period of reperfusion. Suppression of sAC activity in cardiomyocytes and H9C2 cells, either by sAC knockdown, by pharmacological inhibition or by withdrawal of bicarbonate, a natural sAC activator, compromised cell viability and recovery of cytosolic Ca2+ homeostasis during reperfusion. Contrariwise, overexpression of mitochondria-targeted sAC in H9C2 cells suppressed reperfusion-induced cell death. Analyzing cAMP concentration in mitochondrial matrix we found that inhibition of PDE2, a predominant mitochondria-localized PDE isoform in mammals, during reperfusion significantly increased cAMP level in mitochondrial matrix, but not in cytosol. Accordingly, PDE2 inhibition attenuated reperfusion-induced cardiomyocyte death and improved recovery of the cytosolic Ca2+ homeostasis.

Conclusion

sAC plays an essential role in supporting cardiomyocytes viability during reperfusion. Elevation of mitochondrial cAMP pool either by sAC overexpression or by PDE2 inhibition beneficially affects cardiomyocyte survival during reperfusion.  相似文献   
83.
Understanding how to source agricultural raw materials sustainably is challenging in today’s globalized food system given the variety of issues to be considered and the multitude of suggested indicators for representing these issues. Furthermore, stakeholders in the global food system both impact these issues and are themselves vulnerable to these issues, an important duality that is often implied but not explicitly described. The attention given to these issues and conceptual frameworks varies greatly—depending largely on the stakeholder perspective—as does the set of indicators developed to measure them. To better structure these complex relationships and assess any gaps, we collate a comprehensive list of sustainability issues and a database of sustainability indicators to represent them. To assure a breadth of inclusion, the issues are pulled from the following three perspectives: major global sustainability assessments, sustainability communications from global food companies, and conceptual frameworks of sustainable livelihoods from academic publications. These terms are integrated across perspectives using a common vocabulary, classified by their relevance to impacts and vulnerabilities, and categorized into groups by economic, environmental, physical, human, social, and political characteristics. These issues are then associated with over 2,000 sustainability indicators gathered from existing sources. A gap analysis is then performed to determine if particular issues and issue groups are over or underrepresented. This process results in 44 “integrated” issues—24 impact issues and 36 vulnerability issues —that are composed of 318 “component” issues. The gap analysis shows that although every integrated issue is mentioned at least 40% of the time across perspectives, no issue is mentioned more than 70% of the time. A few issues infrequently mentioned across perspectives also have relatively few indicators available to fully represent them. Issues in the impact framework generally have fewer gaps than those in the vulnerability framework.  相似文献   
84.
Three species of the cosmopolitan genus Ulva (U. paschima , U. chaugulii and U. ohnoi ) from the Persian Gulf were identified using morphological and molecular markers, and were analyzed for total lipids, fatty acids, proteins and amino acid profiles. Our results show that the studied Ulva species have high protein content (9?25% dry weight), contain essential fatty acids and nearly all essential amino acids. This suggests Ulva could have potential as a form of human nutrition and animal feed with a low carbon footprint.  相似文献   
85.
Post-translation modification (PTM) of cysteine S-sulfenylation sites in protein is important in cellular biology. S-sulfenylation plays a significant role  相似文献   
86.
Emerging evidence indicates that some altered patterns of methylation that occur in breast tumors may also be found in breast tissue of healthy women in relation to the breast cancer (BC) risk factors. Progesterone receptor (PR) isoform α is a crucial regulator of breast hormone responsiveness and its hypermethylation plays an important role in the initiation and development of breast tumors. However, such a methylation change in healthy women and its link with the different risk factors has not yet been investigated. In the present study, we aimed to examine the relationship of possible methylation changes within a critical region in the promoter CpG island of PGR-α (progesterone receptor α) gene in the healthy women with a set of reproductive and nonreproductive BC risk factors. The breast tissues were collected from 120 cancer-free women who had undergone cosmetic mammoplasty. The genomic DNA was extracted from the breast tissues and the methylation level of PGR-α promoter CpG island was determined by using MeDIP-qPCR assay. Using regression analysis, we found that increasing menarche age is inversely associated with the high methylation of PGR-α promoter ( β = −0.790, SE = 0.362; P = 0.031). Although lactating women had more methylation than nonlactating women (P = 0.026, the t test), this result was not confirmed by regression models. Such an observation may be helpful in better understanding of the underlying mechanisms by which early age at menarche increases the risk of BC. However, this perspective requires further validations in larger studies of more subjects as well as the inclusion of other related genes.  相似文献   
87.
Efficient plant regeneration was achieved from callus derived from immature-cotyledon explants of oleaster (Elaeagnus angustifolia L.). Calli were obtained on MS media containing 3% sucrose and different concentrations of TDZ. The highest rate of green, compact and nodular callus was formed on MS medium supplemented with 1 mg/l of TDZ. Shoot organogenesis was achieved when the callus was transferred onto MS media containing 3% sucrose and BA alone (05–4 mg/l) or BA (0.5 and 1 mg/l) combined with NAA or IAA (0.5 and 1 mg/l). Maximum organogenesis was obtained with 1 mg/l BA in combination with 0.5 mg/l NAA. Rooting of the shoots was achieved on MS medium supplemented with 0.2 mg/l IBA. Regenerated plantlets were acclimatized and successfully transplanted to soil.  相似文献   
88.
Plant Ecology - Modeling plant habitat range distributions is critical for monitoring and restoring species in their natural habitat. The classical logistic regression (LR) model for plant habitat...  相似文献   
89.
Alu-mediated rearrangement of tumor suppressor genes occurs frequently during carcinogenesis. In breast cancer, this mechanism contributes to loss of the wild-type BRCA1 allele in inherited disease and to loss of heterozygosity in sporadic cancer. To identify genes required for suppression of Alu-mediated recombination we performed a genomewide screen of a collection of 4672 yeast gene deletion mutants using a direct repeat recombination assay. The primary screen and subsequent analysis identified 12 candidate genes including TSA, ELG1, and RRM3, which are known to play a significant role in maintaining genomic stability. Genetic analysis of the corresponding human homologs was performed in sporadic breast tumors and in inherited BRCA1-associated carcinomas. Sequencing of these genes in high risk breast cancer families revealed a potential role for the helicase PIF1 in cancer predisposition. PIF1 variant L319P was identified in three breast cancer families; importantly, this variant, which is predicted to be functionally damaging, was not identified in a large series of controls nor has it been reported in either dbSNP or the 1000 Genomes Project. In Schizosaccharomyces pombe, Pfh1 is required to maintain both mitochondrial and nuclear genomic integrity. Functional studies in yeast of human PIF1 L319P revealed that this variant cannot complement the essential functions of Pfh1 in either the nucleus or mitochondria. Our results provide a global view of nonessential genes involved in suppressing Alu-mediated recombination and implicate variation in PIF1 in breast cancer predisposition.  相似文献   
90.
Fu J  Hashem Y  Wower I  Lei J  Liao HY  Zwieb C  Wower J  Frank J 《The EMBO journal》2010,29(22):3819-3825
Bacterial ribosomes stalled by truncated mRNAs are rescued by transfer-messenger RNA (tmRNA), a dual-function molecule that contains a tRNA-like domain (TLD) and an internal open reading frame (ORF). Occupying the empty A site with its TLD, the tmRNA enters the ribosome with the help of elongation factor Tu and a protein factor called small protein B (SmpB), and switches the translation to its own ORF. In this study, using cryo-electron microscopy, we obtained the first structure of an in vivo-formed complex containing ribosome and the tmRNA at the point where the TLD is accommodated into the ribosomal P site. We show that tmRNA maintains a stable 'arc and fork' structure on the ribosome when its TLD moves to the ribosomal P site and translation resumes on its ORF. Based on the density map, we built an atomic model, which suggests that SmpB interacts with the five nucleotides immediately upstream of the resume codon, thereby determining the correct selection of the reading frame on the ORF of tmRNA.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号