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   464篇
  免费   36篇
  2021年   12篇
  2020年   4篇
  2019年   7篇
  2018年   5篇
  2017年   7篇
  2016年   10篇
  2015年   19篇
  2014年   16篇
  2013年   30篇
  2012年   23篇
  2011年   21篇
  2010年   21篇
  2009年   20篇
  2008年   17篇
  2007年   16篇
  2006年   13篇
  2005年   21篇
  2004年   25篇
  2003年   15篇
  2002年   16篇
  2001年   6篇
  2000年   7篇
  1999年   7篇
  1998年   4篇
  1997年   3篇
  1995年   5篇
  1994年   6篇
  1992年   11篇
  1991年   6篇
  1990年   15篇
  1989年   6篇
  1988年   6篇
  1987年   6篇
  1986年   5篇
  1985年   5篇
  1984年   4篇
  1983年   7篇
  1982年   6篇
  1981年   3篇
  1979年   9篇
  1978年   3篇
  1977年   3篇
  1976年   3篇
  1975年   4篇
  1973年   3篇
  1971年   3篇
  1970年   8篇
  1968年   2篇
  1966年   3篇
  1965年   3篇
排序方式: 共有500条查询结果,搜索用时 343 毫秒
91.

Background

Morbid obesity can be a life threatening condition. The aim of our study is to assess the trend in morbid obesity in The Netherlands among children of Dutch origin since 1980, and among children of Turkish and Moroccan origin since 1997.

Methods and Findings

Cross-sectional height and weight data of children of Dutch, Turkish and Moroccan origin aged 2–18 years were selected from three national Dutch Growth Studies performed in 1980, 1997 and 2009 (n = 54,814). Extended international (IOTF) cut-offs in childhood were used to define morbid obesity (obesity class II and III combined). The morbidity index for overweight was calculated as the prevalence of morbid obesity divided by the prevalence of overweight. Our study showed that the prevalence of morbid obesity in children of Dutch origin was 0.59% in boys and 0.53% in girls in 2009. Significant upward trends occurred since 1980 and 1997. The prevalence was three to four fold higher in Turkish children compared to Dutch children. The Turkish children also had an upward trend since 1997, but this was only statistically significant in boys. The prevalence of morbid obesity in Moroccan children was two to three fold higher than in Dutch children, but it remained almost stable between 1997 and 2009. The Dutch and Turkish children showed an upward trend in morbidity index for overweight since respectively 1980 and 1997, while the Moroccan children showed a downward trend since 1997. In 2009, children of low educated parents had the highest prevalence rates of morbid obesity; 1.06% in Dutch, 2.11% in Turkish and 1.41% in Moroccan children.

Conclusions and Significance

An upward trend of morbid obesity in Dutch and Turkish children in The Netherlands occurred. Monitoring and reducing the prevalence of childhood morbid obesity is of high importance for these children, health care and the community.  相似文献   
92.
93.
The toxin Doc from the phd/doc toxin-antitoxin module targets the cellular translation machinery and is inhibited by its antitoxin partner Phd. Here we show that Phd also functions as a chaperone, keeping Doc in an active, correctly folded conformation. In the absence of Phd, Doc exists in a relatively expanded state that is prone to dimerization through domain swapping with its active site loop acting as hinge region. The domain-swapped dimer is not capable of arresting protein synthesis in vitro, whereas the Doc monomer is. Upon binding to Phd, Doc becomes more compact and is secured in its monomeric state with a neutralized active site.  相似文献   
94.
Using the fluorescent anion 8-anilino-1-naphthalenesulphonate (ANS) for determining the membrane surface potential necessitates that the intrinsic affinity constant Ki for the ANS sites be known. Two methods are presented which do not rely on a determination of Ki at high ionic strength. They are respectively applied to neutral membranes (egg phosphatidylcholine liposomes) and highly charged natural ones (horse bean microsomes and liposomes from their phospholipids). The value of Ki appears to be insensitive to the level of occupancy of the sites, the KCl concentration and the pH in large ranges. Furthermore, the classical Gouy-Chapman model seems to describe correctly the whole set of data, provided apparent mean molecular areas larger than the published crystallographic ones are admitted.  相似文献   
95.
Beta subunits have been dissociated from CF1 of spinach chloroplasts, purified by HPLC and characterized by two-dimensional electrophoresis and fluorescence emission. The solutions of isolated beta subunits are able to hydrolyze MgATP; this ATPase activity is an intrinsic property of the beta molecule. From proton NMR at 300 and 500 MHz, it is shown that the preparations are fully reproducible and that beta subunits remain monomeric with 75% aliphatic protons associated with rigid parts of the molecule. The other 25% give rise to separate resonances and belong to mobile side-chains and/or to flexible regions. The measurement of the transverse relaxation times T2 has permitted a detailed characterization of the molecular dynamics of the isolated beta subunits.  相似文献   
96.
97.
We report in a previous study the presence of a large conductance K+ channel in the membrane of rough endoplasmic reticulum (RER) from rat hepatocytes incorporated into lipid bilayers. Channel activity in this case was found to decrease in presence of ATP 100 µM on the cytoplasmic side and was totally inhibited at ATP concentrations greater than 0.25 mM. Although such features would be compatible with the presence of a KATP channel in the RER, recent data obtained from a brain mitochondrial inner membrane preparation have provided evidence for a Maxi-K channel which could also be blocked by ATP within the mM concentration range. A series of channel incorporation experiments was thus undertaken to determine if the ATP-sensitive channel originally observed in the RER corresponds to KATP channel. Our results indicate that the gating and permeation properties of this channel are unaffected by the addition of 800 nM charybdotoxin and 1 µM iberiotoxin, but appeared sensitive to 10 mM TEA and 2.5 mM ATP. Furthermore, adding 100 µM glibenclamide at positive potentials and 400 µM tolbutamide at negative or positive voltages caused a strong inhibition of channel activity. Finally Western blot analyses provided evidence for Kir6.2, SUR1 and/or SUR2B, and SUR2A expression in our RER fractions. It was concluded on the basis of these observations that the channel previously characterized in RER membranes corresponds to KATP, suggesting that opening of this channel may enhance Ca2+ releases, alter the dynamics of the Ca2+ transient and prevent accumulation of Ca2+ in the ER during Ca2+ overload.  相似文献   
98.
99.
100.
Incubation in a culture medium with and without TSH of 16 day-old foetal thyroid glands induces hypertrophy of the Golgi apparatus which may be correlated with a considerable increase in the number of secretory vesicles. A stereological study performed during the first 6 hr of incubation showed that: vesicle secretion was biphasic; vesicle secretion was heterogeneous with two different populations of vesicles; When TSH (20 mU and 80 mU) was added to the medium, the volume density of the follicular lumina increased; at least during the first 6 hr TSH seemed to be necessary to the formation of follicular lumina.  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