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   124篇
  免费   7篇
  国内免费   5篇
  2023年   2篇
  2022年   3篇
  2021年   4篇
  2020年   2篇
  2019年   5篇
  2018年   6篇
  2017年   5篇
  2016年   4篇
  2015年   4篇
  2014年   9篇
  2013年   9篇
  2012年   5篇
  2011年   6篇
  2010年   8篇
  2009年   5篇
  2008年   1篇
  2007年   4篇
  2006年   6篇
  2005年   4篇
  2004年   3篇
  2002年   3篇
  2001年   2篇
  2000年   2篇
  1999年   1篇
  1998年   2篇
  1994年   1篇
  1991年   1篇
  1986年   1篇
  1985年   4篇
  1984年   2篇
  1983年   2篇
  1982年   4篇
  1981年   1篇
  1980年   4篇
  1979年   1篇
  1978年   2篇
  1977年   1篇
  1976年   1篇
  1975年   2篇
  1974年   4篇
排序方式: 共有136条查询结果,搜索用时 15 毫秒
1.
Adenylyl cyclase‐associated protein (CAP) is a highly conserved protein. Previous reports have suggested that CAP1 may be a negative regulator of cellular proliferation, migration, and adhesion and the development of cell carcinomas. The molecular mechanism of CAP1 regulation of downstream pathways, as well as how CAP1 is regulated by environmental stimuli and upstream signalling, is not well understood. In this present study, we assessed the role of CAP1 in milk synthesis and proliferation of bovine mammary epithelial cells. Using gene overexpression and silencing methods, CAP1 was found to negatively regulate milk synthesis and proliferation of cells via the PI3K‐mTOR/SREBP‐1c/Cyclin D1 signalling pathway. Hormones, such as prolactin and oestrogen, and amino acids, such as methionine and leucine, stimulate MMP9 expression and trigger CAP1 degradation, and thus, abrogate its inhibition of synthesis of milk protein, fat, and lactose by and proliferation of bovine mammary epithelial cells. The results of our study help deepen our understanding of the regulatory mechanisms underlying milk synthesis and aid in characterizing the molecular mechanisms of CAP1. Previous reports have suggested that CAP1 is a negative regulator of cellular proliferation and anabolism, but the molecular mechanisms are largely unknown. In this present study, we identified CAP1 as a negative regulator of milk synthesis and proliferation of bovine mammary epithelial cells. Our results will deepen our understanding of the regulatory mechanisms underlying milk synthesis and aid in exploring the molecular mechanisms of CAP1.  相似文献   
2.
Phosphoserine phosphatase (PSP) catalyzes the final and irreversible step of L‐serine synthesis by hydrolyzing phosphoserine to produce L ‐serine and inorganic phosphate. Developing a therapeutic drug that interferes with serine production is of great interest to regulate the pathogenicity of some bacteria and control D ‐serine levels in neurological diseases. We determined the crystal structure of PSP from the hyperthermophilic archaeon Thermococcus onnurineus at 1.8 Å resolution, revealing an NDSB ligand bound to a novel site that is located in a fissure between the catalytic domain and the CAP module. The structure shows a half‐open conformation of the CAP 1 module with a unique protruding loop of residues 150–155 that possesses a helical conformation in other structures of homologous PSPs. Activity assays indicate that the enzyme exhibits marginal PSP activity at low temperature but a sharp increase in the kcat/KM value, approximately 22 fold, when the temperature is increased. Structural and biochemical analyses suggest that the protruding loop in the active site might be an essential component for the regulation of the activity of PSP from hyperthermophilic T. onnurineus. Identification of this novel binding site distantly located from the catalytic site may be exploited for the development of effective therapeutic allosteric inhibitors against PSP activity. © Proteins 2013. © 2012 Wiley Periodicals, Inc.  相似文献   
3.
This study was conducted to establish the contribution of genetic host factors in the susceptibility to community acquired pneumonia (CAP) in the Russian population. Patients with CAP (n = 334), volunteers without a previous history of CAP, constantly exposed to infectious agents, control A group (n = 141) and a second control group B consisted of healthy persons (n = 314) were included in the study. All subjects were genotyped for 13 polymorphic variants in the genes of xenobiotics detoxification CYP1A1 (rs2606345, rs4646903, and rs1048943), GSTM1 (Ins/del), GSTT1 (Ins/del), ABCB1 rs1045642); immune and inflammation response IL-6 (rs1800795), TNF-a (rs1800629), MBL2 (rs7096206), CCR5 (rs333), NOS3 (rs1799983), angiotensin-converting enzyme ACE (rs4340), and occlusive vascular disease/hyperhomocysteinemia MTHFR (rs1801133). Seven polymorphic variants in genes CYP1A1, GSTM1, ABCB1, NOS3, IL6, CCR5 and ACE were associated with CAP. For two genes CYP1A1 and GSTM1 associations remained significant after correction for multiple comparisons. Multiple analysis by the number of all risk genotypes showed a highly significant association with CAP (P = 2.4 × 10− 7, OR = 3.03, 95% CI 1.98–4.64) with the threshold for three risk genotypes. Using the ROC-analysis, the AUC value for multi-locus model was estimated as 68.38.  相似文献   
4.
EU expenditures for Rural Development, having increased from 2.9% of the total Common Agricultural Policy (CAP) budget in the 1990s to 12.3% in the beginning of the 2010s, reflect the growing strategic and societal values attached to this policy in addressing the new global challenges for rural areas in the enlarged EU. The analysis of the recent and ongoing reforms shows that Rural Development Programmes (RDP) made substantial progress towards sectoral integration and thematic broadening, and, at the same time, provided continuity of well-established and important measures. Yet, under growing budget constraints, better targeting of funds becomes even more crucial (European Court of Auditors, 2011). Comparing the design and allocation practices of Regional RDPs, however, reveals significant differences in targeting strategies, all too often based on the implementation history and experience of previous periods. Better availability, coordination and digital connectivity of expenditure data and other data sources across the EU encouraged the adoption of the Common Monitoring and Evaluation Framework (CMEF), aimed at more clearly depicting intervention needs and effects at the regional scale (NUTS2–NUTS3) (NUTS (Nomenclature des unités territoriales statistiques) is a EU geocode standard for referencing spatial subunits for statistical purposes). The EU project SPARD (Spatial Analysis of Rural Development Measures) took those data as a starting point to find out more about the causal relationships between RD measure implementation, and their determining factors and impacts with a specific look at their spatial dimension: in which rural development measures is success determined by neighbourhood conditions, and at what scale? SPARD developed and applied new methodological approaches, particularly spatial econometrics, to evaluate selected measures that contribute to improved competitiveness, environmental performance and rural viability. The results are presented in this special issue in four thematic foci:
  • •Analysing RDP performance by applying spatial econometric modelling (theory, procedures, key results) on RDP payments at the national and European scale.
  • •Effectiveness and efficiency of RDP participation towards impacts at the regional scale: an in-depth view of European case studies, specific measures, indicators and shortcomings of the CMEF.
  • •Learning about spatial and non-spatial determinants of participation in RDP.
  • •Experiences and requirements related to the CAP 2020 and the improvement of the CMEF.
Overall, the results emphasise the difficulty of evaluating of RDPs, even when using much more sophisticated instruments than those used in the current evaluation practices. While a lack of appropriate information remains an issue, the experience of SPARD also underscores the challenge of matching the quest for generalised approaches and the need to consider ad hoc local determinants, as well as the trade-off between the benefits of higher precision and the costs of implied information burden.  相似文献   
5.
目的:分析儿童社区获得性金葡菌肺炎应用利奈唑胺的临床疗效.方法:选择2008-1-1至2009-3-1在青岛大学医学院附属医院普通儿科及青岛市儿童医院诊断社区获得性金葡菌肺炎患儿22人为研究对象,分析其体温、咳嗽、肺部罗音、住院时间等临床资料.结果:患儿的平均住院时间为13.0±2.26天,有效率100%,不良反应发生率4.55%.结论:利奈唑胺治疗儿童社区获得性金葡菌肺炎有较高的临床治愈率,可快速改善症状.缩短住院时间.  相似文献   
6.
Regulation of the DNA binding affinity of an oligomeric protein can be considered to consist of an intrinsic component, in which the affinity of an individual DNA‐binding domain is modulated in response to effector binding, and an extrinsic component, in which the relative position of the protein's two DNA‐binding domains are altered so that they can or cannot contact both half‐site operators simultaneously. We demonstrated directly that the TetR repressor utilizes an extrinsic mechanism and CAP, the catabolite activator protein, utilizes an intrinsic mechanism.  相似文献   
7.
植物的单价阳离子:质子逆向转运蛋白-1(CAP1)基因家族是一类在盐胁迫中起重要作用的基因,分为液泡膜单价阳离子:质子逆向转运蛋白和质膜单价阳离子:质子逆向转运蛋白两大类,在植物的发育和生长过程中起到很重要的作用.不同的成员在植物中的表达特性不同.主要综述了此类基因的结构、启动子活性、表达情况及其主要功能.  相似文献   
8.
9.
The use of mouse models in experimental research is of enormous importance for the study of hepatic physiology and pathophysiological disturbances. However, due to the small size of the mouse, technical details of the intraoperative monitoring procedure suitable for the mouse were rarely described. Previously we have reported a monitoring procedure to obtain hemodynamic parameters for rats. Now, we adapted the procedure to acquire systemic and hepatic hemodynamic parameters in mice, a species ten-fold smaller than rats. This film demonstrates the instrumentation of the animals as well as the data acquisition process needed to assess systemic and hepatic hemodynamics in mice. Vital parameters, including body temperature, respiratory rate and heart rate were recorded throughout the whole procedure. Systemic hemodynamic parameters consist of carotid artery pressure (CAP) and central venous pressure (CVP). Hepatic perfusion parameters include portal vein pressure (PVP), portal flow rate as well as the flow rate of the common hepatic artery (table 1). Instrumentation and data acquisition to record the normal values was completed within 1.5 h. Systemic and hepatic hemodynamic parameters remained within normal ranges during this procedure.This procedure is challenging but feasible. We have already applied this procedure to assess hepatic hemodynamics in normal mice as well as during 70% partial hepatectomy and in liver lobe clamping experiments. Mean PVP after resection (n= 20), was 11.41±2.94 cmH2O which was significantly higher (P<0.05) than before resection (6.87±2.39 cmH2O). The results of liver lobe clamping experiment indicated that this monitoring procedure is sensitive and suitable for detecting small changes in portal pressure and portal flow rate. In conclusion, this procedure is reliable in the hands of an experienced micro-surgeon but should be limited to experiments where mice are absolutely needed.  相似文献   
10.
根据实验测定的Ⅰ类金属硫蛋白(metallothionein, MT)三级结构的实验数据,给出该类蛋白质的两种特征结构(CXC、CXXC一级结构,半胱氨酸-金属络合簇三级结构)的原子间距离约束条件,然后运用距离几何算法计算出一系列可能的构象.从这些构象中经统计分析筛选出目标函数值显著较小的结构作为所预测蛋白质的三级结构模型.用已知结构的蓝蟹MT对方法进行检验证实其可行性后,对植物炭疽病真菌金属硫蛋白CAP3进行了三级结构预测.  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