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   1420800篇
  免费   113938篇
  国内免费   3359篇
耳鼻咽喉   18691篇
儿科学   47466篇
妇产科学   41429篇
基础医学   201379篇
口腔科学   38294篇
临床医学   126815篇
内科学   285988篇
皮肤病学   33704篇
神经病学   117635篇
特种医学   54230篇
外国民族医学   464篇
外科学   212797篇
综合类   32811篇
现状与发展   3篇
一般理论   493篇
预防医学   110261篇
眼科学   31795篇
药学   99070篇
  1篇
中国医学   3409篇
肿瘤学   81362篇
  2021年   10987篇
  2019年   11807篇
  2018年   16873篇
  2017年   12921篇
  2016年   14552篇
  2015年   16230篇
  2014年   22898篇
  2013年   33907篇
  2012年   46023篇
  2011年   48736篇
  2010年   28566篇
  2009年   27271篇
  2008年   44912篇
  2007年   47558篇
  2006年   48100篇
  2005年   46670篇
  2004年   44451篇
  2003年   42368篇
  2002年   40803篇
  2001年   73267篇
  2000年   74838篇
  1999年   61747篇
  1998年   17063篇
  1997年   15478篇
  1996年   15630篇
  1995年   14821篇
  1994年   13416篇
  1993年   12596篇
  1992年   45854篇
  1991年   43489篇
  1990年   41494篇
  1989年   39552篇
  1988年   36181篇
  1987年   35353篇
  1986年   32864篇
  1985年   31281篇
  1984年   23823篇
  1983年   20026篇
  1982年   12209篇
  1981年   10781篇
  1979年   20707篇
  1978年   14584篇
  1977年   12086篇
  1976年   11369篇
  1975年   11620篇
  1974年   13993篇
  1973年   13534篇
  1972年   12635篇
  1971年   11469篇
  1970年   10911篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Objectives: There is a paucity of reporting on surgical outcomes of isolated posterior cruciate ligament reconstruction (PCLR). We hypothesize that isolated PCL injuries failing nonoperative treatment achieve good outcomes and are able to return to sport following PCLR.

Methods: A retrospective analysis was performed to identify patients with isolated PCL injuries that underwent reconstruction between 2001 and 2014. Patients with multi-ligamentous injury or another concomitant knee pathology were excluded. Medical records were reviewed for demographic, clinical and operative data. Patients were contacted for administration of a telephone-based questionnaire which included the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation form, Lysholm-Tegner scales, Marx activity scale (MAS), return to sport status, and patient satisfaction instruments.

Results: A total of 15 isolated PCL reconstructions in 14 patients with a mean age of 27.5 years (range 17–43) met the study inclusion criteria; mean follow up was 6.3 years (range 1.4–15.2). Pre-operatively, the primary complaint was knee instability in all patients; on physical examination, lack of a firm end point during posterior drawer testing was found in 93% (14/15) of the knees. In total, 12 of 15 knees underwent transtibial, single-bundle PCLR and three of 15 underwent tibial inlay, double bundle PCLR. Graft types included: quadriceps autograft (7/15), Achilles allograft (6/15), and hamstring autograft (2/15). There were no graft failures in our patient cohort. At most recent follow up the mean scores respectively on the IKDC form, Lysholm-Tegner scales and MAS were (standard deviation): 77.3 (16.5), 83.1 (17.9), 6.13 (2.6), and 7.1 (6.0). All fourteen patients were athletes prior to their injury and 79% (11/14) returned to sport and overall patient satisfaction was 9.2/10.

Conclusions: Isolated PCLR provides good outcomes at mean medium-term follow up with restoration of function, high rate of return to sport and overall patient satisfaction.  相似文献   

12.

Background

Physicians treating nonvalvular atrial fibrillation (AF) assess stroke and bleeding risks when deciding on anticoagulation. The agreement between empirical and physician-estimated risks is unclear. Furthermore, the association between patient and physician sex and anticoagulation decision-making is uncertain.

Methods

We pooled data from 2 national primary care physician chart audit databases of patients with AF (Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation and Coordinated National Network to Engage Physicians in the Care and Treatment of Patients with Atrial Fibrillation Chart Audit) with a combined 1035 physicians (133 female, 902 male) and 10,927 patients (4567 female and 6360 male).

Results

Male physicians underestimated stroke risk in female patients and overestimated risk in male patients. Female physicians estimated stroke risk well in female patients but underestimated the risk in male patients. Risk of bleeding was underestimated in all. Despite differences in risk assessment by physician and patient sex, > 90% of patients received anticoagulation across all subgroups. There was modest agreement between physician estimated and calculated (ie, CHADS2 score) stroke risk: Kappa scores were 0.41 (0.35-0.47) for female physicians and 0.34 (0.32-0.36) for male physicians.

Conclusions

Our study is the first to examine the association between patient and physician sex influences and stroke and bleeding risk estimation in AF. Although there were differences in agreement between physician estimated stroke risk and calculated CHADS2 scores, these differences were small and unlikely to affect clinical practice; further, despite any perceived differences in the accuracy of risk assessment by sex, most patients received anticoagulation.  相似文献   
13.

Background and aims

It is not known whether non alcoholic fatty liver disease (NAFLD) is a risk factor for diabetes in non obese, non centrally-obese subjects. Our aim was to investigate relationships between fatty liver, insulin resistance and a biomarker score for liver fibrosis with incident diabetes at follow up, in subjects who were neither obese nor centrally-obese.

Methods and results

As many as 70,303 subjects with a body mass index (BMI) < 25 kg/m2 and without diabetes were followed up for a maximum of 7.9 years. At baseline, fatty liver was identified by liver ultrasound, insulin resistance (IR) by homeostatic model assessment of insulin resistance (HOMA-IR) ≥2.0, and central obesity by waist circumference (waist circumference ≥90 cm (men) and ≥85 cm (women). The Fibrosis-4 (FIB-4 score) was used to estimate extent of liver fibrosis. Cox proportional hazards models adjusted for confounders were used to estimate hazard ratios (aHRs) for incident diabetes. As many as 852 incident cases of diabetes occurred during follow up (median [IQR] 3.71 [2.03] years). Mean ± SD BMI was 22.8 ± 1.8 and 21.7 ± 2.0 kg/m2 in subjects with and without diabetes at follow up. In subjects without central obesity and with fatty liver, aHRs (95% CI) for incident diabetes at follow up were 2.17 (1.56, 3.03) for men, and 2.86 (1.50,5.46) for women. Similar aHRs for incident diabetes occurred with fatty liver, IR and the highest quartile of FIB-4 combined, in men; and there was a non significant trend toward increased risk in women.

Conclusions

In normal weight, non-centrally obese subjects NAFLD is an independent risk factor for incident diabetes.  相似文献   
14.
15.
ABSTRACT

Purpose

To investigate the effect of 1% tropicamide on anterior chamber aqueous flare (ACAF) measurements acquired with laser flare meter in patients with pseudoexfoliation.  相似文献   
16.

Purpose

The purpose of this study was to evaluate trends in demographics and outcomes of pediatric breast cancer in a United States population-based cohort.

Methods

The Surveillance, Epidemiology, and End Results (SEER) database was utilized to identify all pediatric patients with malignant breast tumors between 1973 and 2014. Analysis was performed using Stata Statistical Software version 13.1. Associations between categorical variables were made using X2 test. Log-rank test was used for univariate survival analysis. Kaplan–Meier analysis investigated five-year survival rates across several variables. Adjusted analysis was performed using a Cox Proportional-Hazards regression.

Results

134 patients with breast malignancies were identified. Carcinoma was the most prevalent histology (48.5%), followed by fibroepithelial tumors (FETs) (35.1%), and sarcoma (14.2%). FETs were twice as common in black compared to nonblack patients (56.3% vs. 29.0%, p?<?0.01). Analyzing histology by stage revealed that 100% of FETs were early stage disease (p?<?0.0001). 46.7% of the tumors tested were ER/PR negative, more than twice as many compared to the published adult estimate of 20.0%. Unadjusted survival analysis revealed worse survival for patients with adenocarcinoma/sarcomas, advanced stage, and high grade disease, without a survival difference between races.

Conclusion

Breast cancer remains a rare malignancy among pediatric patients. Although black patients were found to have more noncarcinomatous tumors with less advanced disease, this did not confer a survival advantage.

Type of study

Retrospective cohort study.

Level of evidence

Level III.  相似文献   
17.
18.

Background

We have recently shown that human epididymis protein 4 (HE4) levels correlate with the severity of cystic fibrosis (CF) lung disease. However, there are no data on how HE4 levels alter in patients receiving CFTR modulating therapy.

Methods

In this retrospective clinical study, 3 independent CF patient cohorts (US-American: 29, Australian: 12 and Irish: 19 cases) were enrolled carrying at least one Class III CFTR CF-causing mutation (p.Gly551Asp) and being treated with CFTR potentiator ivacaftor. Plasma HE4 was measured by immunoassay before treatment (baseline) and 1–6?months after commencement of ivacaftor, and were correlated with FEV1 (% predicted), sweat chloride, C-reactive protein (CRP) and body mass index (BMI).

Results

After 1?month of therapy, HE4 levels were significantly lower than at baseline and remained decreased up to 6?months. A significant inverse correlation between absolute and delta values of HE4 and FEV1 (r?=??0.5376; P?<?.001 and r?=??0.3285; P?<?.001), was retrospectively observed in pooled groups, including an independent association of HE4 with FEV1 by multiple regression analysis (β?=??0.57, P?=?.019). Substantial area under the receiver operating characteristic curve (ROC-AUC) value was determined for HE4 when 7% mean change of FEV1 (0.722 [95% CI 0.581–0.863]; P?=?.029) were used as classifier, especially in the first 2?months of treatment (0.806 [95% CI 0.665–0.947]; P?<?.001).

Conclusions

This study shows that plasma HE4 levels inversely correlate with lung function improvement in CF patients receiving ivacaftor. Overall, this potential biomarker may be of value for routine clinical and laboratory follow-up of CFTR modulating therapy.  相似文献   
19.
Chronic transplant dysfunction is a complex dynamic pathogenic process. Clinically, a decrease in glomerular filtration rate (GFR) becomes apparent leading to chronic renal insufficiency and dialysis or death from cardiovascular events. Chronic transplant dysfunction can develop into a chronic alIograft nephropathy (CAN) as a specific entity with dynamic progression. CAN includes a collection of immunologic and non-immunologic factors, rejection, ischemia time, donor and recipient characteristics and toxicity of calcineurin inhibitors. Despite improvements in immunosuppression, the long-range prognosis of renal allografts has not improved. Whether modern immunosuppressive concepts with reduction or avoidance of calcineurin inhibitors and a therapy based on antimetabolites, such as mycophenolate or mTOR-inhibitors could lead to a prolongation of transplant survival, remains to be seen.  相似文献   
20.
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