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   235篇
  免费   13篇
  2023年   3篇
  2022年   4篇
  2021年   7篇
  2020年   2篇
  2019年   3篇
  2018年   1篇
  2017年   7篇
  2016年   9篇
  2015年   9篇
  2014年   12篇
  2013年   9篇
  2012年   21篇
  2011年   18篇
  2010年   9篇
  2009年   12篇
  2008年   11篇
  2007年   20篇
  2006年   31篇
  2005年   19篇
  2004年   12篇
  2003年   8篇
  2002年   8篇
  2001年   10篇
  2000年   2篇
  1991年   1篇
排序方式: 共有248条查询结果,搜索用时 15 毫秒
1.
Cerebrohepatorenal malformation is a rare familial disorder characterized by typical renal lesions combined with Dandy-Walker malformation, and congenital hepatic fibrosis. In this case report, a male premie with the diagnosis of cerebrorenal syndrome or so called Goldston syndrome is presented. Besides the rarity of this syndrome, this case is the second reported patient diagnosed prenatally.  相似文献   
2.
Broadening the genetic base of crops is crucial for developing varieties to respond to global agricultural challenges such as climate change. Here, we analysed a diverse panel of 371 domesticated lines of the model crop barley to explore the genetics of crop adaptation. We first collected exome sequence data and phenotypes of key life history traits from contrasting multi‐environment common garden trials. Then we applied refined statistical methods, including some based on exomic haplotype states, for genotype‐by‐environment (G×E) modelling. Sub‐populations defined from exomic profiles were coincident with barley's biology, geography and history, and explained a high proportion of trial phenotypic variance. Clear G×E interactions indicated adaptation profiles that varied for landraces and cultivars. Exploration of circadian clock‐related genes, associated with the environmentally adaptive days to heading trait (crucial for the crop's spread from the Fertile Crescent), illustrated complexities in G×E effect directions, and the importance of latitudinally based genic context in the expression of large‐effect alleles. Our analysis supports a gene‐level scientific understanding of crop adaption and leads to practical opportunities for crop improvement, allowing the prioritisation of genomic regions and particular sets of lines for breeding efforts seeking to cope with climate change and other stresses.  相似文献   
3.
The therapeutic effects of abemaciclib (ABE), an inhibitor of cyclin- dependent kinases (CDK) 4/6, on the proliferation of two types of prostate cancer (PC) cells were revealed. In this study, in vitro cytotoxic and apoptotic effects of ABE on metastatic castration-resistant prostate cancer (mCRPC) androgen receptor (AR) negative PC-3 and AR mutant LNCaP PC cells were analyzed with WST-1, Annexin V, cell cycle, reactive oxygen species (ROS), mitochondrial membrane potential, RT-PCR, western blot, and apoptosis protein array. ABE considerably inhibited the growth of PC cells in a dose-dependent manner (p<0.01) and caused significant apoptotic cell death through the suppression of CDK4/6-Cyclin D complex, ROS generation and depolarization of mitochondria membrane potential. However, PC-3 cells were more sensitive to ABE than LNCaP cells. Furthermore, the expression levels of several pro-apoptotic and cell cycle regulatory proteins were upregulated by ABE in especially PC-3 cells with the downregulation of apoptotic inhibitor proteins. Our results suggest that ABE inhibits PC cell growth and promotes apoptosis and thus ABE treatment may be a promising treatment strategy in especially mCRPC. Further preclinical and clinical studies should be performed to clarify the clinical use of ABE for the treatment of PC.  相似文献   
4.
Many pathogenic missense mutations are found in protein positions that are neither well-conserved nor fall in any known functional domains. Consequently, we lack any mechanistic underpinning of dysfunction caused by such mutations. We explored the disruption of allosteric dynamic coupling between these positions and the known functional sites as a possible mechanism for pathogenesis. In this study, we present an analysis of 591 pathogenic missense variants in 144 human enzymes that suggests that allosteric dynamic coupling of mutated positions with known active sites is a plausible biophysical mechanism and evidence of their functional importance. We illustrate this mechanism in a case study of β-Glucocerebrosidase (GCase) in which a vast majority of 94 sites harboring Gaucher disease-associated missense variants are located some distance away from the active site. An analysis of the conformational dynamics of GCase suggests that mutations on these distal sites cause changes in the flexibility of active site residues despite their distance, indicating a dynamic communication network throughout the protein. The disruption of the long-distance dynamic coupling caused by missense mutations may provide a plausible general mechanistic explanation for biological dysfunction and disease.  相似文献   
5.
The prevalence of extended-spectrum beta-lactamase (ESBL) production by 194 nosocomial isolates of Enterobacteriacea recovered from 1995 to 1999 was investigated. The ESBL production was determined by the double-disk synergy test and was confirmed by the E-test ESBL strip. Twenty-three isolates (21 Klebsiella pneumoniae, one Escherichia coli, one Providencia rettgeri) were found as ESBL-producers (11.8%). These isolates were also usually resistant to non-betalactam antibiotics. Most of them contained a beta-lactamase with a pI of 7.6. All the strains conjugally transferred their ESBLs to recipient E. coli. Contrary to others, ESBL-producing K. pneumoniae strains isolated in 1999 were resistant to ciprofloxacin, and had the identical plasmid profiles suggestive of an outbreak. Ciprofloxacin resistance in these strains could not be transferred. In conclusion, K. pneumoniae was the main ESBL-producing species among nosocomial isolates of Enterobacteriacae in our hospital.  相似文献   
6.
Cyanovirin-N (CVN), a cyanobacterial lectin, exemplifies a class of antiviral agents that inhibit HIV by binding to the highly glycosylated envelope protein gp120. Here, we investigate the energetics of glycan recognition using a computationally inexpensive flexible docking approach, backbone perturbation docking (BP-Dock). We benchmarked our method using two mutants of CVN: P51G-m4-CVN, which binds dimannose with high affinity through domain B, and CVN(mutDB), in which binding to domain B has been abolished through mutation of five polar residues to small nonpolar side chains. We investigated the energetic contribution of these polar residues along with the additional position 53 by docking dimannose to single-point CVN mutant models. Analysis of the docking simulations indicated that the E41A/G and T57A mutations led to a significant decrease in binding energy scores due to rearrangements of the hydrogen-bond network that reverberated throughout the binding cavity. N42A decreased the binding score to a level comparable to that of CVN(mutDB) by affecting the integrity of the local protein structure. In contrast, N53S resulted in a high binding energy score, similar to P51G-m4-CVN. Experimental characterization of the five mutants by NMR spectroscopy confirmed the binding affinity pattern predicted by BP-Dock. Despite their mostly conserved fold and stability, E41A, E41G, and T57A displayed dissociation constants in the millimolar range. N53S showed a binding constant in the low micromolar range, similar to that observed for P51G-m4-CVN. No binding was observed for N42A. Our results show that BP-Dock is a useful tool for rapidly screening the relative binding affinity pattern of in silico-designed mutants compared with wild-type, supporting its use to design novel mutants with enhanced binding properties.  相似文献   
7.
The aim of the work was to investigate antitumoral effect of essential oils on cancer cells and their possible protective (antioxidant) effects against hydrogen peroxide-induced cytotoxicity. Also, in vitro antioxidant properties of essential oils and aqueous extracts from wild form and cultivated form of Salvia pisidica were compared.  相似文献   
8.
9.
In this study we aimed to evaluate serum insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3) and growth hormone (GH) levels in children with congenital heart disease (CHD) and to determine if these parameters have any relationship to the cyanosis, nutritional status and the left ventricular systolic function. This study is prospective-randomized study which conducted in 94 CHD patients (36 girls and 58 boys, aged between one 1-192 months, 19 cyanotic CHD and 75 acyanotic CHD) and age-sex matched 54 children (26 girls and 28 boys) with no CHD. In the study group, 37 out of the 94 CHD patients (39.4%) and 16 out of the 54 controls (29.6%) had malnutrition. The difference between the cyanotic and acyanotic patients in respect to malnutrition was significant (57.9% and 34.6%, p<0.05). Serum IGF-1 levels were lower (41.8+/-3.9 microg/L, 106.9+/-17.9 microg/L respectively, p<0.001) and GH levels were higher (6.43+/-0.9 ng/ml, 3.87+/-0.5 respectively, p<0.05) in CHD patient group than the controls. Serum IGF-1 levels were significantly lower in cyanotic CHD patients than the acyanotic patients (17.2+/-3.2 microg/L, 48.7.0+/-4.6 microg/L respectively, p<0.001) and serum IGF-1 levels were both lower in acyanotic and cyanotic CHD patients than the controls (p<0.001 for both). Serum IGF-1 and GH levels were similar between the well-nourished CHD patients and CHD patients with malnutrition (p>0.05). In total study group, the most effective factors on serum IGF-1 levels was presence of CHD (p<0.001), in CHD patients, the presence of cyanosis is the most effective factor on serum IGF-1 level, the presence of malnutrition is the most effective factor on serum IGFBP-3 levels (p<0.01). In the acyanotic, cyanotic, and the entire CHD patient groups, we find no correlations between the serum IGF-1, IGFBP-3 levels and left ventricular systolic function measurements. But serum GH levels were negatively correlated with diastolic left ventricular interseptum diameter, diastolic left ventricular mass and left ventricular end-diastolic volume measurements in CHD patients. In conclusion, we determined that the most important factor on serum IGF-1 levels is cyanosis. Reduced IGF1 levels and decreased left ventricular mass with an elevated GH levels in CHD patients and these findings are prominent in the cases with cyanosis and malnutrition. For this reason we believe that chronic hypoxia plays a significant role in the pathogenesis of malnutrition and also we believe that IGF-1 deficiency seen in CHD patients may be responsible in the etiology of the decrease in left ventricular mass independently from GH.  相似文献   
10.
The origin of modern wheats involved alloploidization among related genomes. To determine if Aegilops speltoides was the donor of the B and G genomes in AABB and AAGG tetraploids, we used a 3-tiered approach. Using 70 amplified fragment length polymorphism (AFLP) loci, we sampled molecular diversity among 480 wheat lines from their natural habitats encompassing all S genome Aegilops, the putative progenitors of wheat B and G genomes. Fifty-nine Aegilops representatives for S genome diversity were compared at 375 AFLP loci with diploid, tetraploid, and 11 nulli-tetrasomic Triticum aestivum wheat lines. B genome-specific markers allowed pinning the origin of the B genome to S chromosomes of A. speltoides, while excluding other lineages. The outbreeding nature of A. speltoides influences its molecular diversity and bears upon inferences of B and G genome origins. Haplotypes at nuclear and chloroplast loci ACC1, G6PDH, GPT, PGK1, Q, VRN1, and ndhF for approximately 70 Aegilops and Triticum lines (0.73 Mb sequenced) reveal both B and G genomes of polyploid wheats as unique samples of A. speltoides haplotype diversity. These have been sequestered by the AABB Triticum dicoccoides and AAGG Triticum araraticum lineages during their independent origins.  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