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   786篇
  免费   66篇
  国内免费   2篇
  2021年   12篇
  2020年   8篇
  2019年   6篇
  2018年   10篇
  2017年   7篇
  2016年   18篇
  2015年   41篇
  2014年   42篇
  2013年   57篇
  2012年   49篇
  2011年   54篇
  2010年   40篇
  2009年   41篇
  2008年   45篇
  2007年   48篇
  2006年   52篇
  2005年   40篇
  2004年   42篇
  2003年   43篇
  2002年   36篇
  2001年   11篇
  2000年   7篇
  1999年   10篇
  1998年   12篇
  1997年   6篇
  1996年   6篇
  1995年   3篇
  1994年   8篇
  1993年   7篇
  1992年   4篇
  1991年   3篇
  1990年   6篇
  1989年   4篇
  1987年   4篇
  1985年   4篇
  1984年   4篇
  1983年   4篇
  1982年   7篇
  1981年   5篇
  1980年   8篇
  1979年   3篇
  1977年   2篇
  1975年   3篇
  1974年   4篇
  1973年   3篇
  1972年   2篇
  1971年   3篇
  1969年   3篇
  1965年   2篇
  1964年   3篇
排序方式: 共有854条查询结果,搜索用时 15 毫秒
41.

Introduction

One in three people will be diagnosed with diabetes by 2050, and the proportion will likely be higher among Native Americans. Diabetes control is currently suboptimal in underserved populations despite a plethora of new therapies. Patient empowerment is a key determinant of diabetes control, but such empowerment can be difficult to achieve due to resource limitation and cultural, language and health literacy barriers. We describe a home-based educational intervention using Community Health Representatives (CHRs), leading to improvement in Patient Activation Measures scores and clinical indicators of diabetes control.

Methods

Sixty participants with type 2 diabetes (T2D) completed a baseline evaluation including physical exam, Point of Care (POC) testing, and the Patient Activation Measure (PAM) survey. Participants then underwent a one hour group didactic session led by Community Health Representatives (CHRs) who subsequently carried out monthly home-based educational interventions to encourage healthy lifestyles, including diet, exercise, and alcohol and cigarette avoidance until follow up at 6 months, when clinical phenotyping and the PAM survey were repeated.

Results

PAM scores were increased by at least one level in 35 (58%) participants, while 24 participants who started at higher baseline score did not change. Six months after intervention, mean levels of A1C decreased by 0.7 ± 1.2%; fasting blood glucose decreased by 24.0 ± 38.0 mg/dl; BMI decreased by 1.5 ± 2.1 kg/m2; total cholesterol decreased by 12.0± 28.0 mg/dl; and triglycerides decreased by 52.0 ± 71.0 mg/dl. All of these changes were statistically significant (p<0.05).

Conclusion

This six month, CHR led and community-oriented educational intervention helps inform standards of practice for the management of diabetes, engages diabetic populations in their own care, and reduces health disparities for the underserved population of Zuni Indians.

Trial Registration

ClinicalTrials.gov NCT02339311  相似文献   
42.
Gaseous neurotransmitters such as nitric oxide (NO) provide a unique and often overlooked mechanism for neurons to communicate through diffusion within a network, independent of synaptic connectivity. NO provides homeostatic control of intrinsic excitability. Here we conduct a theoretical investigation of the distinguishing roles of NO-mediated diffusive homeostasis in comparison with canonical non-diffusive homeostasis in cortical networks. We find that both forms of homeostasis provide a robust mechanism for maintaining stable activity following perturbations. However, the resulting networks differ, with diffusive homeostasis maintaining substantial heterogeneity in activity levels of individual neurons, a feature disrupted in networks with non-diffusive homeostasis. This results in networks capable of representing input heterogeneity, and linearly responding over a broader range of inputs than those undergoing non-diffusive homeostasis. We further show that these properties are preserved when homeostatic and Hebbian plasticity are combined. These results suggest a mechanism for dynamically maintaining neural heterogeneity, and expose computational advantages of non-local homeostatic processes.  相似文献   
43.
An agricultural soil was treated with dairy-waste compost, ammonium-sulfate fertilizer or no added nitrogen (control) and planted to silage corn for 6 years. The kinetics of nitrification were determined in laboratory-shaken slurry assays with a range of substrate concentrations (0-20 mM NH(4)(+)) over a 24-h period for soils from the three treatments. Determined concentrations of substrate and product were fit to Michaelis-Menten and Haldane models. For all the treatments, the Haldane model was a better fit, suggesting that significant nitrification inhibition may occur in soils under high ammonium conditions similar to those found immediately after fertilization or waste applications. The maximum rate of nitrification (V(max)) was significantly higher for the fertilized and compost-treated soils (1.74 and 1.50 mmol N kg(-1) soil day(-1)) vs. control soil (0.98 mmol kg(-1) soil day(-1)). The K(m) and K(i) values were not significantly different, with average values of 0.02 and 27 mM NH(4)(+), respectively. Our results suggest that both N sources increased nitrifier community size, but did not shift the nitrifier community structure in ways that influenced enzyme affinity or sensitivity to ammonium. The K(m) values are comparable to those determined directly in other soils, but are substantially lower than those from most pure cultures of ammonia-oxidizing bacteria.  相似文献   
44.
45.
The Cdc6 protein is an essential component of pre-replication complexes (preRCs), which assemble at origins of DNA replication during the G1 phase of the cell cycle. Previous studies have demonstrated that, in response to ionizing radiation, Cdc6 is ubiquitinated by the anaphase promoting complex (APC(Cdh1)) in a p53-dependent manner. We find, however, that DNA damage caused by UV irradiation or DNA alkylation by methyl methane sulfonate (MMS) induces Cdc6 degradation independently of p53. We further demonstrate that Cdc6 degradation after these forms of DNA damage is also independent of cell cycle phase, Cdc6 phosphorylation of the known Cdk target residues, or the Cul4/DDB1 and APC(Cdh1) ubiquitin E3 ligases. Instead Cdc6 directly binds a HECT-family ubiquitin E3 ligase, Huwe1 (also known as Mule, UreB1, ARF-BP1, Lasu1, and HectH9), and Huwe1 polyubiquitinates Cdc6 in vitro. Degradation of Cdc6 in UV-irradiated cells or in cells treated with MMS requires Huwe1 and is associated with release of Cdc6 from chromatin. Furthermore, yeast cells lacking the Huwe1 ortholog, Tom1, have a similar defect in Cdc6 degradation. Together, these findings demonstrate an important and conserved role for Huwe1 in regulating Cdc6 abundance after DNA damage.  相似文献   
46.
47.
Ftm is a novel basal body protein of cilia involved in Shh signalling   总被引:1,自引:0,他引:1  
In this study we show in mice that Ftm (Rpgrip1l) is located at the ciliary basal body. Our data reveal that Ftm is necessary for developmental processes such as the establishment of left-right asymmetry and patterning of the neural tube and the limbs. The loss of Ftm affects the ratio of Gli3 activator to Gli3 repressor, suggesting an involvement of Ftm in Shh signalling. As Ftm is not essential for cilia assembly but for full Shh response, Ftm can be considered as a novel component for cilium-related Hh signalling. Furthermore, the absence of Ftm in arthropods underlines the divergence between vertebrate and Drosophila Hh pathways.  相似文献   
48.
The aim of the present work was to investigate the effect of physical structures on the properties of starch granules. Starches with a high amylopectin content possessing A- and B-type crystallinity were chosen for the study. The gelatinization temperature decreased in the following order: maize (A) > potato (B) > wheat (A) > barley (A), which did not reflect a correlation with the type of crystallinity. Low values of gelatinization temperature were accompanied with high free surface energy of the crystallites. It is proposed that these data are caused by different types of imperfections in starch crystals. Annealing resulted in an enhancement of the gelatinization temperature and a decrease of the free surface energy of the crystallites for all starches reflecting a partial improvement of crystalline perfection. A limited acid hydrolysis (lintnerization) of the starches decreased the gelatinization temperature because of a partial disruption of the crystalline lamellae and an increase of the amount of defects on the edges of the crystallites. Annealing of the lintnerized starches improved the structure of maize and potato starch, giving them similar structural and physicochemical parameters, which was opposite the behavior of the annealed sample from wheat. The possible nature of removable and nonremovable defects inside the crystalline region of the starch granules is discussed. It is concluded that, besides the allomorphic A- and B-types of crystal packing, physical defects in the crystals possess a major impact on starch gelatinization.  相似文献   
49.
Conspecific brood parasitism (CBP) is an alternative reproductive tactic found in many animals with parental care. Parasitizing females lay eggs in the nests of other females (hosts) of the same species, which incubate and raise both their own and the foreign offspring. The causes and consequences of CBP are debated. Using albumen fingerprinting of eggs for accurately detecting parasitism, we here analyse its relation to female condition and clutch size in High Arctic common eiders Somateria mollissima borealis. Among 166 clutches in a Svalbard colony, 31 (19%) contained eggs from more than one female, and 40 of 670 eggs (6%) were parasitic. In 6 cases an active nest with egg(s) was taken over by another female. Many suitable nest sites were unoccupied, indicating that CBP and nest takeover are reproductive tactics, not only consequences of nest site shortage. Similarity in body mass between female categories suggests that condition does not determine whether a nesting female becomes parasitised. There was no evidence of low condition in parasites: egg size was similar in hosts and parasites, and parasitism was equally frequent early and late in the laying season. Meta‐analysis of this and 3 other eider studies shows that there is a cost of being parasitised in this precocial species: host females laid on average 7% fewer eggs than other females.  相似文献   
50.
The importance of local chromatin structure in regulating replication initiation has become increasingly apparent. Most recently, histone methylation and nucleosome positioning have been added to the list of modifications demonstrated to regulate origins. In particular, the methylation states of H3K4, H3K36 and H4K20 have been associated with establishing active, repressed or poised origins depending on the timing and extent of methylation. The stability and precise positioning of nucleosomes has also been demonstrated to affect replication efficiency. Although it is not yet clear how these modifications alter the behavior of specific replication factors, ample evidence establishes their role in maintaining coordinated replication. This review will summarize recent advances in understanding these aspects of chromatin structure in DNA replication origin control.Key words: chromatin, histone methylation, nucleosome positioning, nucleosome stability, origin, post-translational modification, replication  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