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   612篇
  免费   56篇
  国内免费   4篇
耳鼻咽喉   7篇
儿科学   14篇
妇产科学   7篇
基础医学   82篇
口腔科学   14篇
临床医学   55篇
内科学   172篇
皮肤病学   9篇
神经病学   21篇
特种医学   23篇
外科学   108篇
综合类   23篇
预防医学   33篇
眼科学   13篇
药学   65篇
中国医学   4篇
肿瘤学   22篇
  2023年   25篇
  2022年   20篇
  2021年   25篇
  2020年   19篇
  2019年   22篇
  2018年   35篇
  2017年   16篇
  2016年   24篇
  2015年   24篇
  2014年   35篇
  2013年   49篇
  2012年   57篇
  2011年   51篇
  2010年   33篇
  2009年   21篇
  2008年   26篇
  2007年   27篇
  2006年   20篇
  2005年   21篇
  2004年   12篇
  2003年   13篇
  2002年   11篇
  2001年   8篇
  2000年   8篇
  1999年   15篇
  1998年   6篇
  1997年   6篇
  1996年   5篇
  1993年   2篇
  1992年   3篇
  1991年   6篇
  1989年   1篇
  1988年   3篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1979年   1篇
  1977年   2篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1968年   1篇
  1965年   1篇
  1939年   1篇
排序方式: 共有672条查询结果,搜索用时 309 毫秒
121.
122.
AIM: To examine variation in risk factors that contributed to dementia among four elderly cohorts by race and gender. METHODS: We examined 2008 Tennessee Hospital Discharged database for vascular factors that play a role in both stroke and dementia. Risk factors for dementia were examined for black and white patients aged 65+. Four race-gender groups of patients-white males(WM), black males(BM), white females(WF), and black females(BF) were compared for prevalence of dementia and stroke. A logistic model predicting dementia in each group separately used several vascular factors affectingdementia directly or indirectly through stroke. RESULTS: Three point six percent of patients hospitalized in 2008 had dementia and dementia was higher among females than males(3.9% vs 3.2%, P 0.001), and higher among blacks than whites(4.2% vs 3.5%, P 0.000). Further, BF had higher prevalence of dementia than WF(4.2% vs 3.8%, P 0.001); similarly BM had more dementia than WM(4.1% vs 3.1%, P 0.001). In logistic regression models, however, different patterns of risk factors were associated with dementia in four groups: among WF and WM, hypertension, diabetes, congestive heart failure, and stroke predicted dementia. Among BF and BM, only stroke and diabetes were related to dementia.CONCLUSION: Aggressive management of risk factors(hypertension and diabetes) may subsequently reduce stroke and dementia hospitalization.  相似文献   
123.
The main characteristics of clindamycin are adequate for treatment of osteoarticular infections (OAI): good bone diffusion, broad spectrum of antibacterial activity and oral use.  相似文献   
124.
125.
BACKGROUND: Cerebrovascular accident (CVA) is the third leading cause of death and disability in developed countries. Anyone suspected of having a stroke should be taken immediately to a medical facility for diagnosis and treatment. The symptoms that follow a stroke aren't significant and depend on the area of the brain that has been affected and the amount of tissue damaged. Parameters for predicting long-term outcome in such patients have not been clearly delineated, therefore the aim of this study was to investigate this possibility and to test a system that might practicably be used routinely to aid management and predict outcomes of individual stroke patients.  相似文献   
126.
127.
128.
Micronutrient interactions give rise to complex issues that have an impact on preventive strategies when multiple micronutrient deficiencies coexist. The aim of this population-based study was to determine the prevalence of vitamins A and E and iron deficiencies among women 15 to 49 years of age in the northern Persian Gulf region. We hypothesized that serum retinol levels may show correlations with hemoglobin (Hb) concentrations, independent of iron status. A total of 1242 nonpregnant women of reproductive age were selected via a multistage stratified random cluster sampling technique. Serum ferritin and soluble transferrin receptor levels were measured using enzyme immunoassay techniques. Serum retinol (vitamin A) and α-tocopherol (vitamin E) were determined for 727 women by high-performance liquid chromatography. The prevalence of anemia (Hb <12 g/dL), iron deficiency (serum ferritin <15 μg/L), and iron deficiency anemia was 8.7%, 25.4%, and 4.6%, respectively. Vitamin A (<0.7 μmol/L) and vitamin E (<11.6 μmol/L) deficiencies were found in 1.2% and 5.9% of the studied population, respectively. Multiple regression analysis revealed that serum retinol levels exhibit a significant association with Hb concentrations after controlling for serum ferritin levels, anemia associated with chronic disease, and risk factors for anemia. Therefore, most nonpregnant women of reproductive age in the northern Persian Gulf were found to have adequate serum vitamin A and E levels. However, the status of anemia and iron deficiency anemia could be considered a mild public health problem in this region. On the basis of multivariate analyses, we conclude that low serum retinol levels may contribute to anemia, independent of iron homeostasis.  相似文献   
129.
130.

Ethnopharmacological relevance

Leaf decoctions of Carica papaya have been traditionally used in some parts of Indonesia to treat and prevent malaria. Leaf extracts and fraction have been previously shown to possess antiplasmodial activity in vitro and in vivo.

Materials and methods

Antiplasmodial activity of extracts was confirmed and the active fractions in the extract were identified by HPLC-based activity profiling, a gradient HPLC fractionation of a single injection of the extract, followed by offline bioassay of the obtained microfractions. For preparative isolation of compounds, an alkaloidal fraction was obtained via adsorption on cationic ion exchange resin. Active compounds were purified by HPLC–MS and MPLC–ELSD. Structures were established by HR-ESI-MS and NMR spectroscopy. For compounds 5 and 7 absolute configuration was confirmed by comparison of experimental and calculated electronic circular dichroism (ECD) spectroscopy data, and by X-ray crystallography. Compounds were tested for bioactivity in vitro against four parasites (Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani, and Plasmodium falciparum), and in the Plasmodium berghei mouse model.

Results

Profiling indicated flavonoids and alkaloids in the active time windows. A total of nine compounds were isolated. Four were known flavonols – manghaslin, clitorin, rutin, and nicotiflorin. Five compounds isolated from the alkaloidal fraction were piperidine alkaloids. Compounds 5 and 6 were inactive carpamic acid and methyl carpamate, while three alkaloids 79 showed high antiplasmodial activity and low cytotoxicity. When tested in the Plasmodium berghei mouse model, carpaine (7) did not increase the survival time of animals.

Conclusions

The antiplasmodial activity of papaya leaves could be linked to alkaloids. Among these, carpaine was highly active and selective in vitro. The high in vitro activity could not be substantiated with the in vivo murine model. Further investigations are needed to clarify the divergence between our negative in vivo results for carpaine, and previous reports of in vivo activity with papaya leaf extracts.  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