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   1588篇
  免费   127篇
  国内免费   8篇
耳鼻咽喉   22篇
儿科学   62篇
妇产科学   35篇
基础医学   197篇
口腔科学   38篇
临床医学   182篇
内科学   351篇
皮肤病学   38篇
神经病学   95篇
特种医学   48篇
外科学   184篇
综合类   21篇
预防医学   112篇
眼科学   50篇
药学   162篇
中国医学   27篇
肿瘤学   99篇
  2024年   5篇
  2023年   21篇
  2022年   57篇
  2021年   94篇
  2020年   52篇
  2019年   89篇
  2018年   100篇
  2017年   65篇
  2016年   88篇
  2015年   63篇
  2014年   109篇
  2013年   109篇
  2012年   137篇
  2011年   161篇
  2010年   91篇
  2009年   78篇
  2008年   96篇
  2007年   66篇
  2006年   56篇
  2005年   42篇
  2004年   30篇
  2003年   26篇
  2002年   26篇
  2001年   7篇
  2000年   12篇
  1999年   13篇
  1998年   4篇
  1997年   3篇
  1996年   1篇
  1995年   2篇
  1994年   2篇
  1992年   1篇
  1990年   2篇
  1989年   1篇
  1986年   1篇
  1979年   2篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1975年   2篇
  1974年   4篇
  1973年   1篇
  1968年   1篇
排序方式: 共有1723条查询结果,搜索用时 15 毫秒
101.
BACKGROUND: Intravascular ultrasound (IVUS) images vary in intensity because of the angle of the transducer relative to the plaque. The purpose of this study was to determine the angle dependence of ultrasound backscatter when the IVUS transducer is aligned coaxially in atherosclerotic arteries and to examine its feasibility in tissue characterization of human atherosclerotic tissue. METHODS AND RESULTS: Thirty-nine noncalcified regions of interest (ROI, 0.4 to 0. 6 mm in diameter) within cross sections of formalin-fixed human iliac arterial plaque were imaged with a 3.9F, 25-MHz IVUS catheter in saline at room temperature. The catheter was moved coaxially from 8 to 16 positions and spanned 50 to 122 degrees relative to the ROI and the lumen center. Echo intensity for each ROI was defined as the videointensity relative to a standard reflector. The angle dependence of echo intensity was defined as the slope of the regression line between the angle of incidence and echo intensity. Each ROI was histologically classified into 4 groups: fibro-acellular (fibrous cap, n=7), fibro-cellular (n=9), fibro-fatty (n=13), or fatty tissue (n=10). The echo intensity of the majority (72%) of plaque components in IVUS images are significantly affected by the angle of incidence of the transducer. The angle dependence of fibro-acellular samples was significantly greater than that of the other 3 groups (4.69 +/- 3.29 x 10(-3) x echo intensity/degree vs 1.06 +/- 1.10 in fibro-cellular area, 2.09 +/- 1.75 in fibro-fatty area, and 2.16 +/- 1.92 in fatty area, P <. 05). CONCLUSIONS: The angle dependence of ultrasound reflections from the fibrous cap of atherosclerotic plaque is another method of tissue characterization in addition to spatial distribution and echo intensity. This technique may be useful in determining the thickness of the fibrous cap, which may be an important predictor of plaque rupture.  相似文献   
102.
Summary: Two allegedly neurotic patients with right iliac fossa pain were investigated with the laparoscope. The findings are described and implications discussed.  相似文献   
103.
Objective Albuminuria is an early marker of renal impairment and a powerful factor of progression of renal disease in type 2 diabetes (T2D). Approximately, one-third of patients with T2D have micro- or macroalbuminuria and these patients have a high risk of progression toward End Stage Renal Disease (ESRD) as well as increased cardiovascular disease. The aim of this study was to determine the prevalence of remission, regression, persistence, and progression of albuminuria, and to evaluate the impact of change in albuminuria on kidney disease and cardiovascular disease in a prospective cohort of patients with T2D. Methods This is a prospective study. The Ethics Committee of Morocco’s Mohammed V University in Rabat approved the study protocol. Inclusion criteria targeted patients who were type 2 diabetics with albuminuria?>30?mg/day, and who had been regularly followed-up in nephrology consultation for at least 36 months. Results Five-hundred twenty-four patients were included. 75.8 and 24.6% of all patients had micro- and macroalbuminuria at enrollment in the study. At the end of the study, 91, 141, 199, and 93 patients had remission, regression, persistence, and progression of albuminuria, respectively. Remission of microalbuminuria to normoalbuminuria was observed in 23.6% of cases. Regression of macroalbuminuria to micro- was observed in 29.9% of cases. Conclusion In our study, the incidence of remission and/or regression of micro- and macroalbuminuria was higher. The incidence of ESRD and the occurrence of cardiac events were greater in the regression, persistence, and progression groups than in the remission of albuminuria group.  相似文献   
104.
105.

Objective

To provide a low-cost and simple model of culturally-appropriate and low cost facilities for improvement of physical activity for girls and their mothers through an after-school program and to determine the changes in anthropometric indexes after this trial.

Methods

This national study was conducted in 2006-2007 in 7 provinces with different socioeconomic situations in Iran. Female students who studied in the 7th through 10th grade and their mothers were selected by random cluster sampling. In each province, 24 sessions of after-school aerobic physical activity were held for 90 minutes, two days a week, and 3 months long at school sites in the afternoon.

Findings

The study comprised 410 participants (204 mothers and 206 daughters), with a mean age of 15.86±1.01 and 40.71±6.3 years in girls and their mothers, respectively. The results of the focus group discussions showed that in general, both mothers and daughters were satisfied from the program and found it feasible and successful. After the trial, the indexes of generalized and abdominal obesity improved significantly both in girls and in their mothers (P-value <0.0001 for weight, body mass index and waist circumference).

Conclusion

Our findings may provide a low-cost and simple effective model of motivation for physical activity with targeted interventions for girls and their mothers. We suggest that the success of this trial might be a result of bonding and accompaniment of mothers and daughters. Such model can be integrated in the existing health and education systems to increase the physical activity level.  相似文献   
106.
107.
AIM: To assess the relation between nutrient patterns and cataract risk. METHODS: This is a hospital-based case-control study with 97 cataract patients and 198 matched controls. Dietary consumption was collected through a valid food frequency questionnaire (FFQ). Nutrient patterns were detected by applying factor analysis. Unconditional logistic regression models were used to estimate odds ratio (ORs) and 95%CIs. RESULTS: We extracted 5 main nutrient patterns. Factor 1 included niacin, thiamin, carbohydrates, protein, zinc, vitamin B6 and sodium (sodium pattern). Factor 2 was characterized by oleic acid, monounsaturated fats, polyunsaturated fats, linoleic acid, trans fatty acid, linolenic acid, vitamin E and saturated fats (fatty acid pattern). The third factor represented high intake of vitamin B12, vitamin D, cholesterol and calcium (mixed pattern). The 4th pattern was high in intake of beta and alpha carotene, vitamin A and vitamin C (antioxidant pattern). Finally, the 5th pattern loaded heavily on docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) (omega-3 pattern). In crude and multivariate analysis, the sodium pattern was associated with increased risk of cataract (OR=1.97, 95%CI: 1.09-3.96). The fatty acid pattern elevated the risk of cataract (OR=1.94, 95%CI: 1.1-3.86). Antioxidant pattern was associated with a significant 79% reduced risk (2nd category compared with the 1st). Omega-3 pattern was significantly negatively associated with risk of cataract (P=0.04). CONCLUSION: These findings imply that nutrient patterns reflecting a combined consumption of nutrients might be important in the etiology of cataract. Additional studies with more efficient designs are warranted to confirm our findings.  相似文献   
108.
This study describes synthesis of a new group of triaryl-1,2,4-oxadiazole derivatives and their anticancer activities. The target compounds were prepared from reaction of different imines and 4-substituted benzohydroxyiminoyl chlorides. All the synthesized compounds were screened for antiproliferative activities against MCF7 and K562 cell lines using MTT assay at 50-μM concentration. Four compounds that showed more than 50 % cytotoxicity were selected for determination of IC50. Out of these, 6c-1y showed remarkable inhibitory cytotoxicity activity against MCF7 and K562 cell lines with IC50 6.50 and 21.66 μM, respectively. A molecular modeling study where 6c-1y was docked in the binding site of COX-2 showed a 2.3-Å hydrogen bond forming via hydroxyl group of Ser516 residue and oxygen of central oxadiazole ring and triaryl moiety of 6c-1y oriented toward the hydrophobic pockets of COX-2. Our data indicate that these derivatives may present promising chemotherapeutic agents, possibly targeting COX-2 pathway.  相似文献   
109.

Background

Cichorium intybus is a medicinal plant commonly used in traditional medicine for its benefits in immune-madiated disorders. There are several evidences showing that C. intybus can modulate immune responses. In the present study we have investigated the effects of the ethanolic root extract of this plant on the immune system by targeting dendritic cells (DCs). For this purpose, phenotypic and functional maturity of murine DCs after treatment with the extract was analyzed by flow cytometry and mixed lymphocyte reaction (MLR) assay.

Results

C. intybus did not change the expression of CD40, CD86 and MHC-II molecules as important co-stimulatory markers on DCs compared to the control, indicating that it could not promote DCs phenotypic maturation. Treatment of DCs with lower concentrations of the extract resulted in an increased production of IL-12 by these cells with no change in IL-10 release. The capacity of treated DCs to stimulate allogenic T cells proliferation and cytokines secretion was examined in the co-cuture of these cells with T cells in MLR. C. intybus at higher concentrations inhibited proliferation of allogenic T cells and in lower concentrations changed the level of cytokines such that IL-4 decreased and IFN-γ increased.

Conclusions

These results indicated that C. intybus extract at higher concentrations can inhibit T cell stimulating activity of DCs, whereas at lower concentrations can modulate cytokine secretion toward a Th1 pattern. These data may in part explain the traditional use of this plant in treatment of immune-mediated disorders.  相似文献   
110.
Across the globe, pharmacists on the frontline continue to fight COVID-19 and its continuously evolving physical, mental, and economic consequences armed by their knowledge, professionalism, and dedication. Their need for credible scientific evidence to inform their practice has never been more urgent. Despite the exponentially increasing number of publications since the start of the pandemic, questions remain unanswered, and more are created, than have been resolved by the increasing number of publications.A panel of leading journal editors was convened by the International Pharmaceutical Federation (FIP) Pharmacy Practice Research Special Interest Group to discuss the current status of COVID-19 related research, provide their recommendations, and identify focal points for pharmacy practice, social pharmacy, and education research moving forward.Key priorities identified spanned a wide range of topics, reflecting the need for good quality research to inform practice and education. The panel insisted that a foundation in theory and use of rigorous methods should continue forming the basis of inquiry and its resultant papers, regardless of topic area. From assessing the clinical and cost effectiveness of COVID-19 therapies and vaccines to assessing different models of pharmaceutical services and education delivery, these priorities will ensure that our practice is informed by the best quality scientific evidence at this very challenging time.  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