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   312篇
  免费   4篇
  国内免费   1篇
  317篇
  2024年   5篇
  2023年   5篇
  2022年   12篇
  2021年   22篇
  2020年   14篇
  2019年   29篇
  2018年   18篇
  2017年   13篇
  2016年   17篇
  2015年   24篇
  2014年   22篇
  2013年   17篇
  2012年   22篇
  2011年   13篇
  2010年   11篇
  2009年   5篇
  2008年   11篇
  2007年   8篇
  2006年   13篇
  2005年   6篇
  2004年   11篇
  2003年   5篇
  2002年   2篇
  2000年   2篇
  1999年   2篇
  1997年   1篇
  1993年   1篇
  1991年   2篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
排序方式: 共有317条查询结果,搜索用时 15 毫秒
91.
Background: Helicobacter pylori infection of the stomach is widespread among human populations and is considered to play a major role in the pathogenesis of various diseases such as peptic ulcer, adenocarcinoma, and mucosa associated lymphoid tissue (MALT) lymphoma of the stomach. To increase H. pylori eradication rate without increasing bacterial resistance, various regimens have been recommended. Commonly the association of at least two antibiotics with a proton‐pump inhibitor is used. The treatment regimens for second‐line therapy, suggested in studies from the western world may not be ideal in Iran. Aim: In this study, we evaluated the safety and efficacy of a new quadruple therapy regimen and compared it with the standard second‐line treatment for H. pylori eradication. Methods: We selected 220 H. pylori positive patients, with a clear indication of eradication therapy, who did not respond to a 2 weeks treatment with metronidazole, amoxicillin, omeprazole, and bismuth. They were randomized into two groups. Group A (n = 110) were treated with azithromycin, ofloxacin, bismuth, and omeprazole and group B (n = 110) with amoxicillin, clarithromycin, bismuth, and omeprazole for 2 weeks. Four weeks after the end of treatment, urea breath test was performed for all subjects to confirm eradication. Results: In intention‐to‐treat analysis, the rate of H. pylori eradication in groups A and B was 77.3% (85/110) and 64.5% (71/110) respectively (p = .027). In per‐protocol analysis, the rate of H. pylori eradication in groups A and B was 86.7 and 74.7%, respectively (p = .026). The incidence of poor compliance was lower, although not significantly so, in group A than group B (3.5 vs 4.3%). No major adverse events occurred in both groups. Conclusion: Two weeks of treatment with ofloxacin, azithromycin, omeprazole, and bismuth is an effective and safe regimen for H. pylori eradication as second‐line therapy.  相似文献   
92.

Aims/Hypothesis

To investigate secular trends in cardiovascular disease (CVD) risk factors during a decade of follow-up in a Middle Eastern cohort, and to compare observed trends between diabetic and non-diabetic populations.

Methods

In a population of 6181 participants (2622 males and 3559 females), diabetes status and CVD risk factors were evaluated in 4 study phases from 1999–2011. 1045 subjects had type 2 diabetes mellitus at baseline and 5136 participants were diabetes-free. To examine the trends of CVD risk factors, generalized estimation equation models were constructed. The interaction between the diabetes status and each phase of the study was checked in a separate model.

Results

During the follow-up period diabetic females significantly gained better control of their blood pressure, serum low density lipoprotein cholesterol and general and central obesity measures compared to non-diabetic counterparts, although 60% of them had high BP and 64% had high serum LDL-C levels till the end of the study. Diabetic males however, experienced significantly better control on their serum LDL-C and general and central obesity measures compared to their non-diabetic controls; but 24% of them were still smoker, 63% had high BP and 60% had high serum LDL-C levels at the end of the follow-up (all Ps interaction <0.05). Use of lipid-lowering and antihypertensive medications increased consistently in both diabetic and non-diabetic populations.

Conclusions/Interpretation

Although CVD risk factors have been controlled to some extent among diabetic population in Iran, still high numbers of people with diabetes have uncontrolled CVD risk factors that prompt more attention.  相似文献   
93.
Silicoflagellates, rare planktonic algae, were registered inbloom-like conditions in the 20-m-deep bottom layer of the Gulfof Trieste, Northern Adriatic. The confusing taxonomy and ecologyof these phytoflagellates, as well as their possible contributionto the oxygen depletion of the bottom layer, is discussed.  相似文献   
94.
    
Odorant or olfactory receptors are mainly localized in the olfactory epithelium for the perception of different odors. Interestingly, many ectopic olfactory receptors with low expression levels have recently been found in nonolfactory tissues to involve in local functions. Therefore, we investigated the probable role of the olfactory signaling pathway in the surrounding microenvironment of oocyte. This study included 22 women in intracytoplasmic sperm injection cycle. The expression of olfactory target molecules in cumulus cells surrounding the growing and mature oocytes was evaluated by Western blotting and real-time polymerase chain reaction. Additionally, integrated bioinformatics analyses were carried out and 6 ectopic olfactory receptors were selected for further evaluation. The initiation of olfactory transduction cascade in cumulus cells of competent oocytes was confirmed by analyzing the expression of adenylyl cyclase type 3 and olfactory market protein. Moreover, the expression pattern of the selected olfactory receptors was evaluated and OR10H2 was selected due to a high level of expression in mature fertile oocytes. We suggested that OR10H2 could be considered as a reliable biomarker for oocyte selection in assisted reproduction technique programs. However, further studies are required to elucidate the role of olfactory transduction cascade in embryo quality and implantation.  相似文献   
95.
OBJECTIVE: To evaluate the value of anatomic and volumetric functional magnetic resonance imaging (MRI) in early assessment of response to trans-arterial chemoembolization (TACE) in hypovascular liver metastases. METHODS: This retrospective study included 52 metastatic lesions (42 targeted and 10 non-targeted) in 17 patients who underwent MRI before and early after TACE. Two reviewers reported response by anatomic criteria (Response Evaluation Criteria in Solid Tumor [RECIST], modified RECIST [mRECIST], and European Association for the Study of Liver Disease [EASL]) and functional criteria (volumetric apparent diffusion coefficient and contrast enhancement). Treatment endpoint was RECIST at 6 months. A 2-sample paired t test was used to compare the mean changes after intra-arterial therapy. P < .05 was considered statistically significant. RESULTS: Reduction in mRECIST and EASL at 1 month was significant in the whole cohort as well as in responders by RECIST at 6 months, and the changes fulfilled partial response criteria for both metrics in responders. Responders also had significant changes in volumetric apparent diffusion coefficient (P = .01 and P = .03) and contrast enhancement (P < .0001 and P < .0001) at 1 month for both readers, respectively. CONCLUSION: At 1 month post treatment, responders did not fulfill RECIST criteria but fulfilled mRECIST and EASL criteria. In addition, volumetric contrast-enhanced and diffusion-weighted MRI may be helpful in evaluating early treatment response after TACE in hypovascular liver metastases in patients who have failed to respond to initial chemotherapy.  相似文献   
96.
A novel lipase has been recently isolated from a local Pseudomonas sp. (GQ243724). In the present study, we have tried to increase the organic solvent stability of this lipase using site-directed mutagenesis. Eight variants N219L, N219I, N219P, N219A, N219R, N219D, S251L, and S251K were designed to change the surface hydrophobicity of this enzyme with respect to the wild-type. Among these variants, the stability of N219L and N219I significantly increased in the presence of all tested organic solvents, whereas two mutants (N219R and N219D) significantly exhibited decreased stabilities in all the organic solvent studied, suggesting that improvement of hydrophobic patches on the enzyme surface enhances the stability in organic media. Furthermore, replacing Ser251 with hydrophobic residues on the enzyme surface dramatically diminished its stability in the tested condition. In spite of the distance of the mutated sites from the active site, the values of k cat and K m were affected. Finally, structural analysis of the wild-type and mutated variants was carried out in the presence and absence of some organic solvents using circular dichroism and fluorescence spectroscopy.  相似文献   
97.
p63 and p73: roles in development and tumor formation   总被引:12,自引:0,他引:12  
The tumor suppressor p53 is critically important in the cellular damage response and is the founding member of a family of proteins. All three genes regulate cell cycle and apoptosis after DNA damage. However, despite a remarkable structural and partly functional similarity among p53, p63, and p73, mouse knockout studies revealed an unexpected functional diversity among them. p63 and p73 knockouts exhibit severe developmental abnormalities but no increased cancer susceptibility, whereas this picture is reversed for p53 knockouts. Neither p63 nor p73 is the target of inactivating mutations in human cancers. Genomic organization is more complex in p63 and p73, largely the result of an alternative internal promoter generating NH2-terminally deleted dominant-negative proteins that engage in inhibitory circuits within the family. Deregulated dominant-negative p73 isoforms might play an active oncogenic role in some human cancers. Moreover, COOH-terminal extensions specific for p63 and p73 enable further unique protein-protein interactions with regulatory pathways involved in development, differentiation, proliferation, and damage response. Thus, p53 family proteins take on functions within a wide biological spectrum stretching from development (p63 and p73), DNA damage response via apoptosis and cell cycle arrest (p53, TAp63, and TAp73), chemosensitivity of tumors (p53 and TAp73), and immortalization and oncogenesis (DeltaNp73).  相似文献   
98.
Summary Our objective was to evaluate the physiological response of Fischerella ambigua FS18 to the combined influence of pH (5, 7 and 9) and light intensity (3 and 300 μmol photon m−2 s−1). Growth rates were similar at pH 9 and pH 7. There was no growth at pH 5. Increasing light intensity did not have any considerable influence on growth rates. Chlorophyll concentration was higher at pH 7 at all light intensities. Chlorophyll concentration decreased with increasing light intensity from 3 to 300 μmol photon m−2 s−1. Synthesis of the phycobiliproteins (PBP), phycocyanin (PC) and allophycocyanin (APC) had the highest rate in pH 7. Increasing irradiance decreased the concentrations of all PBPs. The light-saturated photosynthetic rate was clearly higher at high light intensity. With respect to nitrogenase activity, the highest rate was at pH 9 and 300 μmol photon m−2 s−1. Irradiance did not affect significantly this activity at pH 7. This cyanobacterium seems to be alkalophilic with maximum nitrogenase activity and photosynthesis at pH 9. It can also adapt its photosynthetic apparatus to the variable factors that are found in rice fields.  相似文献   
99.
The aim of the present study was to evaluate the role of endogenous opioids in local sublethal hyperthermia-induced protection against burn injury.Second-degree burn wounds were induced on the back of Balb/c mice. Progression of burn injury and expression of heat shock protein (HSP)-70 were evaluated after 24 h.Both inhibition of HSP synthesis and blocking opioid receptors before applying local sublethal hyperthermia decreased the protective effects of sublethal hyperthermia against the progression of burn injury. Blocking opioid receptors attenuated induction of HSP-70 by sublethal hyperthermia.  相似文献   
100.
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