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   1824篇
  免费   114篇
  国内免费   3篇
耳鼻咽喉   26篇
儿科学   151篇
妇产科学   9篇
基础医学   202篇
口腔科学   15篇
临床医学   138篇
内科学   357篇
皮肤病学   23篇
神经病学   85篇
特种医学   80篇
外科学   233篇
综合类   205篇
一般理论   1篇
预防医学   103篇
眼科学   40篇
药学   129篇
中国医学   12篇
肿瘤学   132篇
  2023年   11篇
  2022年   31篇
  2021年   65篇
  2020年   27篇
  2019年   28篇
  2018年   55篇
  2017年   31篇
  2016年   33篇
  2015年   41篇
  2014年   70篇
  2013年   58篇
  2012年   110篇
  2011年   108篇
  2010年   61篇
  2009年   58篇
  2008年   86篇
  2007年   89篇
  2006年   95篇
  2005年   58篇
  2004年   83篇
  2003年   58篇
  2002年   55篇
  2001年   52篇
  2000年   43篇
  1999年   43篇
  1998年   29篇
  1997年   38篇
  1996年   29篇
  1995年   17篇
  1994年   16篇
  1993年   17篇
  1992年   26篇
  1991年   30篇
  1990年   28篇
  1989年   28篇
  1988年   18篇
  1987年   15篇
  1986年   9篇
  1985年   29篇
  1984年   11篇
  1983年   17篇
  1982年   9篇
  1981年   14篇
  1979年   11篇
  1978年   15篇
  1977年   11篇
  1975年   8篇
  1973年   8篇
  1972年   9篇
  1969年   8篇
排序方式: 共有1941条查询结果,搜索用时 15 毫秒
991.
AimsRecent data have raised concerns about visual outcome following cataract surgery. The aim of this study was to assess the frequency and causes of poor and borderline outcome after cataract surgery in a population-based case series in Satkhira district, Bangladesh.MethodsA population-based case series was conducted within a population-based cluster survey of people aged over 50 years in Satkhira district where 4868 people underwent visual acuity (VA) screening. Eyes operated for cataract with VA<6/18 were examined in detail by an ophthalmologist, including a full history and dilated fundoscopy, to determine the cause of the visual outcome.ResultsCataract surgery was performed on 213 eyes. Outcome was good (VA>6/18) for 128 eyes (60.1%), borderline (VA<6/18 to 6/60) for 35 eyes (16.4%), and poor (VA<6/60) for 50 eyes (23.5%) with available correction. Borderline and poor outcomes were most commonly due to lack of spectacles (25.8%), poor selection (33.8%), or surgical complications (30.6%). Surgical sequelae, namely posterior capsule opacification, was a less common cause of poor or borderline outcome (9.7%).ConclusionsQuality of surgical outcomes is of concern in Satkhira district. Increased emphasis on selection of subjects for surgery, provision of spectacles, and monitoring of surgery may improve outcomes.Eye (2008) 22, 1054-1056; doi:10.1038/sj.eye.6702836; published online 13 April 2007.  相似文献   
992.
AIM: To investigate the age differences in the risk factors, clinicopathological characteristics and patterns of treatment of female breast cancer patients.METHODS: Seven thousand one hundred and fifty-two women with primary breast cancer from the Hong Kong Breast Cancer Registry were recruited after receiving patients’ consent, they were asked to complete standardized questionnaires which captured their sociodemographic characteristics and risk factors associated with breast cancer development. Among them, clinicopathological data and patterns of treatment were further collected from medical records of 5523 patients with invasive breast cancers. Patients were divided into two groups according to the age at diagnosis: younger (< 40 years old) vs older patients (≥ 40 years old) for subsequent analyses.RESULTS: Analysis on the sociodemographic characteristics and exposure to risk factors were performed on 7152 women with primary breast cancer and the results revealed that younger patients were more likely to have unhealthy lifestyles; these include a lack of exercise (85.4% vs 73.2%, P < 0.001), having high stress in life (46.1% vs 35.5%, P < 0.001), having dairy/meat-rich diets (20.2% vs 12.9%, P < 0.001), having alcohol drinking habit (7.7% vs 5.2%, P = 0.002). Younger patients were also more likely to have hormone-related risk factors including nulliparity (43.3% vs 17.8%, P < 0.001) and an early age at menarche (20.7% vs 13.2%, P < 0.001). Analyses on clinicopathological characteristics and patterns of treatment were performed on 5523 women diagnosed with invasive breast cancer. The invasive tumours in younger patients showed more aggressive pathological features such as having a higher percentage of grade 3 histology (45.7% vs 36.5%, P < 0.001), having a higher proportion of tumours with lymphovascular invasion (39.6% vs 33.2%, P = 0.003), and having multifocal disease (15.7% vs 10.3%, P < 0.001); they received different patterns of treatment than their older counterparts.CONCLUSION: Younger patients in Hong Kong are more likely to encounter risk factors associated with breast cancer development and have more aggressive tumours than their older counterparts.  相似文献   
993.
The use of a tourniquet for obtaining a bloodless field is an essential and accepted tool for extremity surgery. A prospective study was done on 30 adult patients undergoing elective limb surgery requiring tourniquet application for haemodynamic and End tidal CO2 (EtCO2) changes. After the induction of general anaesthesia a tourniquet was applied on the limb. There was gradual increase in heart rate & EtCO2 through out the whole period of tourniquet inflation. There was also significant increase of mean arterial pressure during the inflation period. At the end of surgery tourniquet was deflated. Tourniquet time was 76.83+/-16.94 minutes. After deflation of the tourniquet, heart rate & EtCO2 value increased & the values were maximum at 5 minutes. These values came down to the base line at 15 minutes. There was significant decrease of mean arterial pressure (MAP) at 5 minute; it also came to the base at 15 minute. These changes are usually benign but can be significant in patients with co-existing cardiovascular & intracranial diseases. In conclusion, we recommend the haemodynamic and End tidal CO2 monitoring as well as rapid fluid infusion along with hyperventilation for 15-30 minutes after deflation of tourniquet.  相似文献   
994.

Background:

The management of unstable osteoporotic intertrochantric fractures in elderly is challenging because of difficult anatomical reduction, poor bone quality, and sometimes a need to protect the fracture from stresses of weight bearing. Internal fixation in these cases usually involves prolonged bed rest or limited ambulation, to prevent implant failure secondary to osteoporosis. This might result in higher chances of complications like pulmonary embolism, deep vein thrombosis, pneumonia, and decubitus ulcer. The purpose of this study is to analyze the role of primary hemiarthroplasty in cases of unstable osteoporotic intertrochanteric femur fractures.

Materials and Methods:

We retrospectively analyzed 37 cases of primary hemiarthroplasty performed for osteoporotic unstable intertrochanteric fractures (AO/OTA type 31-A2.2 and 31-A2.3 and Evans type III or IV fractures). There were 27 females and 10 males with a mean age of 77.1 years (range, 62–89 years).

Results:

Two patients died due to unrelated cause (myocardial infarction) within 6 months of surgery and remaining 35 patients were followed up to an average of 24.5 months (range,18–39 months). The average surgery time was 71 min (range, 55–88 min) with an average intraoperative blood loss of 350 ml (range, 175–500 ml). Six patients needed blood transfusion postoperatively. The patients walked on an average 3.2 days after surgery (range, 2–8 days). One patient had superficial skin infection and one had bed sore with no other significant postoperative complications. One patient of Alzheimer’s disease refused to walk and had a poor result. A total of 32 out of 35 patients (91%) had excellent to fair functional results and 2 had poor result with respect to the Harris hip score (mean 84.8±9.72, range 58-97). One patient who had neurological comorbidity refused to walk post operatively and was labeled as failed result.

Conclusion:

Hemiarthroplasty for unstable osteoporotic intertrochanteric fractures in elderly results in early ambulation and good functional results although further prospective randomized trials are required before reaching to conclusion.  相似文献   
995.
Integration of infant- and child-feeding index (ICFI) addressing the multidimensional child-feeding practices into one age-specific summary index is gaining importance. This cross-sectional study was aimed at understanding the association between the ICFI and the nutritional status of 259 children, aged 6-23 months, who attended the paediatric outpatient department of the Dhaka Medical College Hospital in Bangladesh. The mean length-for-age z-score (LAZ) of children aged 12-23 months was significantly (p < 0.05) higher among those who were at the upper ICFI tercile compared to those who were at the middle or lower ICFI tercile (-2.01 and -3.20 respectively). A significant correlation was found between the ICFI and the LAZ (r = 0.24, p = 0.01 and r = 0.29, p = 0.01) in children aged 6-8-months and 12-23-months. Multivariable analysis, after adjusting for potential confounders, also found a significant association between the ICFI and the LAZ (beta = 0.13, p = 0.03). The predictive capability of the proposed ICFI on nutritional status of children, especially length-for-age, needs to be further evaluated prospectively among healthy children in the community.  相似文献   
996.
The Brca1 and Brca2 tumor suppressor genes are involved in the maintenance of genomic integrity as they facilitate error free DNA repair. This study was designed to understand the role of Brca1 and Brca2 in betel nut (BN) induced chronic and transgenerational carcinogenesis in mice. Young male and female Swiss Albino mice were chronically as well as transgenerationally exposed to aqueous extract of betel nut (AEBN) in drinking water (2 mg ml(-1)) for up to 24 weeks. In chronically exposed mice, the levels of Brca1 and Brca2 proteins were elevated to approximately 1.4-fold over the age matched controls after 2 weeks of exposure to AEBN, followed by a decline below the controls. In transgenerationally exposed mice, both Brca1 and Brca2 proteins remained below the controls from the onset of AEBN exposure and rapidly declined further, indicating a loss of tumor suppressor protection. Nucleotide sequencing of exon 11 of Brca1 and exon 27 of Brca2 did not reveal mutation in liver nodules of chronically exposed mice, while a G → C mutation Brca1 was observed in liver nodules as well as in solid tumors developing in transgenerationally exposed mice. Thus, the genomic instability arising due to the lowering in the levels of Brca1 and Brca2 proteins and mutation in exon 11 of Brca1 gene contributed to the increased risk of cancer in mice exposed transgenerationally to AEBN.  相似文献   
997.

OBJECTIVE

To examine whether the combination of interferon (IFN)‐α and maitake mushroom D‐fraction (PDF), a bioactive mushroom extract, might potentiate the anticancer activity of IFN‐α in bladder cancer T24 cells in vitro.

MATERIALS AND METHODS

Effects of recombinant IFN‐α2b (0–50 000 IU/mL), PDF (0–700 µg/mL), or their combinations were assessed on T24 cell growth at 72 h. Cell cycle analysis and assays for double‐stranded DNA‐dependent protein kinase (DNA‐PK) were performed to explore possible antiproliferative mechanism of these agents.

RESULTS

IFN‐α2b was able to induce a significant (≈50%) growth reduction at 20 000 IU/mL, which further declined to ≈66% at 50 000 IU/mL. PDF had no effects up to 200 µg/mL, but there was an ≈20% and ≈53% growth reduction at 400 and 700 µg/mL, respectively. When the varying concentrations of IFN‐α2b and PDF were combined, 10 000 IU/mL of IFN‐α2b combined with 200 µg/mL of PDF resulted in an ≈75% growth reduction. This was accompanied by a G1 cell cycle arrest, shown by cell cycle analysis. Concurrently, DNA‐PK activity in IFN‐α2b/PDF‐treated cells was almost three‐fold higher than controls.

CONCLUSIONS

The combination of IFN‐α2b (10 000 IU/mL) and PDF (200 µg/mL) reduced growth by ≈75% in T24 cells. This appears to be due to a synergistic potentiation of these two agents, inducing a G1 arrest with DNA‐PK activation. Therefore, the IFN‐α2b/PDF combination could trigger DNA‐PK activation that may act on the cell cycle to cease cancer cell growth.  相似文献   
998.

Objectives

We conducted a meta‐analysis of studies comparing deferred stenting strategy versus the conventional approach with immediate stenting in patients with ST elevation myocardial infarction.

Background

Deferring stent after mechanical flow restoration has been proposed as a strategy to reduce the risk of “no reflow” in patients with STEMI undergoing primary percutaneous coronary intervention (pPCI). Conflicting evidence is available currently, especially after the recent publication of three randomized clinical trials.

Methods

Searches in electronic databases were performed. Comparisons between the two strategies were performed for both hard clinical endpoints (all cause‐mortality, cardiovascular mortality, unplanned revascularization, myocardial infarction and readmission for heart failure) and surrogate angiographic endpoints (TIMI flow < 3 and myocardial blush grade (MBG) < 2).

Results

Eight studies (three randomized and five non‐randomized) were deemed eligible, accounting for a total of 2101 patients. No difference in terms of hard clinical endpoints was observed between deferred and immediate stenting (OR [95% CI]: 0.79 [0.54‐1.15], for all‐cause mortality; odds ratio (OR) [95% CI]: 0.79 [0.47‐1.31] for cardiovascular mortality; OR [95% CI]: 0.95 [0.64‐1.41] for myocardial infarction; OR [95% CI]: 1.37 [0.87‐2.16], for unplanned revascularization and OR [95% CI]: 0.50 [0.21‐1.17] for readmission for heart failure). Notably, the deferred stenting approach was associated with improved outcome of the surrogate angiographic endpoints (OR [95% CI]: 0.43 [0.18‐0.99] of TIMI flow < 3 and OR [95% CI]: 0.25 [0.11‐0.57] for MBG < 2.

Conclusions

A deferred stenting strategy could be a feasible alternative to the conventional approach with immediate stenting in “selected” STEMI patients undergoing pPCI.
  相似文献   
999.
Herpes zoster ophthalmicus occurs due to reactivation of the varicella zoster virus in the ophthalmic branch of the fifth cranial nerve. This disease primarily affects the elderly as well as the immunocompromised and can result in a wide range of ophthalmic morbidity. Systemic antiviral therapy is the mainstay of treatment; however, consultation with an ophthalmologist is typically indicated. Herein we present a review of this common entity including epidemiology, pathophysiology, evaluation, treatment, follow-up, and an update on the current body of literature.  相似文献   
1000.
Digestive Diseases and Sciences - Long-term outcome and natural history of steroid response in adult ulcerative colitis patients based on short-term response is largely unknown. To evaluate whether...  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