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   458篇
  免费   39篇
  497篇
  2023年   5篇
  2022年   18篇
  2021年   31篇
  2020年   14篇
  2019年   28篇
  2018年   21篇
  2017年   17篇
  2016年   21篇
  2015年   37篇
  2014年   37篇
  2013年   40篇
  2012年   46篇
  2011年   22篇
  2010年   21篇
  2009年   14篇
  2008年   20篇
  2007年   22篇
  2006年   17篇
  2005年   22篇
  2004年   15篇
  2003年   13篇
  2002年   12篇
  1998年   1篇
  1997年   1篇
  1992年   1篇
  1986年   1篇
排序方式: 共有497条查询结果,搜索用时 15 毫秒
31.
Protein complexes play a dominant role in cellular organization and function. Prediction of protein complexes from the network of physical interactions between proteins (PPI networks) has thus become one of the important research areas. Recently, many computational approaches have been developed to identify these complexes. Various performance assessment measures have been proposed for evaluating the efficiency of these methods. However, there are many inconsistencies in the definitions and usage of the measures across the literature. To address this issue, we have gathered and presented the most important performance evaluation measures and developed a tool, named CompEvaluator, to critically assess the protein complex prediction methods. The tool and documentation are publicly available at https://sourceforge.net/projects/compevaluator/files/.  相似文献   
32.
Molecular Biology Reports - Breast Cancer is the most frequent neoplasm diagnosed among women worldwide. Genetic background and lifestyle/environment play a significant role in the disease...  相似文献   
33.
Cytokines such as interleukin-6 (IL-6) and IL-17 which act as key regulators of the immune response have been identified to have a potential role in the bone remodeling mechanism. Receptor activator of NF-κB ligand (RANKL) has been shown to regulate osteoclast differentiation and function while the osteoprotegerin (OPG) blocks the binding of RANKL and inhibits the differentiation of osteoclasts, thus favoring osteogenesis. Alkaline phosphatase (ALP) on the other hand works as early mineralization indicator in bone regulation. The current study aims to determine the potential role of IL-6 and IL-17A in regulating the OPG/RANKL system of the murine osteoblast cell line (MC3T3-E1). Gene expression analysis showed significant up-regulation of OPG and ALP by all the treated groups (rIL-6, rIL-17A and rIL-6 + rIL-17A). In contrast, treatment of cells with rIL-6 and/or rIL-17A showed down-regulation of RANKL expression. Interestingly, the osteoblast cells treated with combinations of rIL-6 + rIL17A showed marked increased in OPG/RANKL ratio. Similar pattern of protein expression was observed in the osteoblasts treated with rIL-6 and/or rIL-17A as detected by western blotting and ELISA. These findings suggest a new mechanism of regulation by these cytokines on the expression of OPG and RANKL, which could promote osteogenesis and diminish osteoclastogenesis.  相似文献   
34.
Accumulation of different metals and metalloids was assessed in two vegetables radish (Raphanus sativus L.) and spinach (Spinacea oleracea L.) irrigated with domestic wastewater in the peri-urban areas of Khushab City, Pakistan. In general, the metal and metalloid concentrations in radish and spinach were higher at site-II treated with sewage water than those found at site-I treated with canal water. In case of radish at both sites the levels of metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, and Pb) were below the permissible level except those of Mn, Ni, Mo, Cd, and Pb. At both sites, the transfer factor ranged from 0.047–228.3 mg kg?1 with Cr having the highest transfer factor. The metal pollution index in soil was in the following order: As > Fe > Ni > Zn > Cd > Mo > Se > Co > Pb > Mn > Cr > Cu, respectively. While in case of spinach at both sites, the concentrations of metals and metalloids in vegetable samples irrigated with canal and sewage water were observed below the permissible level except Mn, Ni, Zn, Mo, and Pb. At both sites, the transfer factor ranged from 0.038–245.4 mg kg?1 with Cr having the highest transfer factor. The metal pollution index in soil was in the following order: Cd > Ni > Co > Se > Mn > Zn > Mo > Pb > Fe > Cr > As > Cu, respectively.  相似文献   
35.
Candida albicans secretes both hydroxamate and phenolate-type siderophores when grown under iron-restricted conditions. The inhibition of candidal growth by iron limitation was reversed by the addition of supplemental hydroxamate on phenolate siderophores. Both siderophores produced equal stimulation of growth suggesting that C. albicans could utilize both siderophores with equal efficiency. Addition of heterologous siderophores from both bacteria and fungi also supported growth of the yeast in a deferrated medium. These results suggest that C. albicans has an iron-uptake mechanism which enables it to obtain iron by utilizing candidal and non-candidal siderophores.  相似文献   
36.
During a virus survey in autumn 2007 and spring 2008 of two Tunisian olive mother blocks, 175 olive samples were collected from 19 different cultivars and tested by RT‐PCR for the presence of Arabis mosaic virus (ArMV), Cherry leaf roll virus (CLRV), Cucumber mosaic virus (CMV), Olive latent ringspot virus (OLRSV), Olive latent virus 1 (OLV‐1), Olive latent virus 2 (OLV‐2), Olive leaf yellowing‐associated virus (OLYaV) and Strawberry latent ringspot virus (SLRSV), using specific sets of primers. The PCR‐negative samples were also subjected to dsRNA and mechanical transmission tests. PCR results indicated that c. 86% of the trees were infected with at least one virus, whereas visible bands were shown by 3 of 24 PCR‐negative samples in dsRNA analysis. OLYaV was the most prevalent virus (49.1%), followed by OLV‐1 (34.3%), CMV (25.7%), OLRSV (16.6%), CLRV (13.1%), SLRSV (7.4%) and OLV‐2 (6.9%), whereas ArMV was not detected. Very high infection rates were found in the two main oil cvs. Chemlali (84.6%) and Chétoui (86.9%).  相似文献   
37.
Dental caries is primarily elicited by modifiable factors such as inadequate oral hygiene, poor dietary practices and deficient fluoride exposure. However, there is a growing body of evidence suggesting the profound influence of genetic factors in dental caries susceptibility. The present study aimed to evaluate the association between single nucleotide polymorphisms (SNPs) in ENAM (rs12640848), MMP20 (rs1784418), TAS2R38 (rs713598), and LTF (rs4547741) genes and early childhood caries (ECC) in Saudi preschool children. This case-control study enrolled 360 Saudi preschool children (262 with ECC and 98 caries-free). Data on environmental factors were collected through a questionnaire. However, caries experience and oral hygiene data were obtained during clinical examination. Buccal swab samples were collected for DNA extraction and SNPs were genotyped using PCR and DNA sequencing. Children with ECC were compared to caries free children (control), then they were categorized into two categories based on ECC severity as follows; non-severe ECC (NS-ECC), and severe-ECC (S-ECC). Association between the SNPs, ECC, NS-ECC, and S-ECC was reported as an odds ratio (OR) with a 95% confidence interval (CI). The majority of the children (72.8%) exhibited ECC (31.7% NS-ECC and 41.1% S-ECC) with mean dmft of 4.20 ± 4.05. Multivariate analyses of environmental factors showed that nocturnal feeding was a risk factor for ECC (P = 0.008). Poor oral hygiene was also a risk factor for both NS-ECC and S-ECC (ECC: P < 0.0001, NS-ECC: P = 0.032 and S-ECC: P < 0.0001). Univariate analysis showed that the AG genotype of rs1784418 of MMP20 gene was protective against ECC (OR = 0.532; 95% CI = 0.316–0.897, P = 0.018) and against NS-ECC (OR = 0.436; 95% CI = 0.238–0.798, P = 0.007). When environmental risk factors for ECC were included as covariates during multivariate analysis, AG variant in rs1784418 of MMP20 gene remained less frequent in NS-ECC cases compared to controls with borderline significance (OR = 0.542; 95% CI = 0.285–1.033, P = 0.063). Our findings concluded that MMP20 rs1784418 SNP might be associated with protection against ECC in Saudi preschool children.  相似文献   
38.
The corpus callosum is the principal cerebral commissure connecting the right and left hemispheres. The development of the corpus callosum is under tight genetic control, as demonstrated by abnormalities in its development in more than 1,000 genetic syndromes. We recruited more than 25 families in which members affected with corpus callosum hypoplasia (CCH) lacked syndromic features and had consanguineous parents, suggesting recessive causes. Exome sequence analysis identified C12orf57 mutations at the initiator methionine codon in four different families. C12orf57 is ubiquitously expressed and encodes a poorly annotated 126 amino acid protein of unknown function. This protein is without significant paralogs but has been tightly conserved across evolution. Our data suggest that this conserved gene is required for development of the human corpus callosum.  相似文献   
39.
The green macroalgae present in freshwater ecosystems have attracted a great attention of the world scientists for removal of heavy metals from wastewater. In this mesocosm study, the uptake rates of heavy metals such as cadmium (Cd), nickel (Ni), chromium (Cr), and lead (Pb) by Oedogonium westi (O. westti) were measured. The equilibrium adsorption capabilities of O. westti were different for Cd, Ni, Cr, and Pb (0.974, 0.418, 0.620, and 0.261 mgg–1, respectively) at 18°C and pH 5.0. Furthermore, the removal efficiencies for Cd, Cr, Ni and Pb were observed from 55–95%, 61–93%, 59–89%, and 61–96%, respectively. The highest removal efficiency was observed for Cd and Cr from aqueous solution at acidic pH and low initial metal concentrations. However, the removal efficiencies of Ni and Pb were higher at high pH and high concentrations of metals in aqueous solution. The results summarized that O. westti is a suitable candidate for removal of selected toxic heavy metals from the aqueous solutions.  相似文献   
40.
Phimosis is the inability of the penis to protrude from the prepuce. In the present report, we present two cases of phimosis in two rhesus monkeys. Surgical enlargement of preputial orifice was performed for unrestricted movement of penis. The exact cause of this condition is unknown to us.  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