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   3931383篇
  免费   294054篇
  国内免费   6773篇
耳鼻咽喉   56525篇
儿科学   124526篇
妇产科学   105561篇
基础医学   565341篇
口腔科学   112403篇
临床医学   361388篇
内科学   751527篇
皮肤病学   83456篇
神经病学   319691篇
特种医学   151387篇
外国民族医学   1277篇
外科学   590578篇
综合类   89569篇
现状与发展   13篇
一般理论   1603篇
预防医学   317491篇
眼科学   93819篇
药学   294172篇
  14篇
中国医学   7556篇
肿瘤学   204313篇
  2018年   42191篇
  2017年   32000篇
  2016年   35742篇
  2015年   40358篇
  2014年   57701篇
  2013年   87741篇
  2012年   119310篇
  2011年   126829篇
  2010年   75440篇
  2009年   71405篇
  2008年   119406篇
  2007年   127244篇
  2006年   128457篇
  2005年   124836篇
  2004年   120087篇
  2003年   115546篇
  2002年   113169篇
  2001年   175025篇
  2000年   180546篇
  1999年   152775篇
  1998年   45586篇
  1997年   40435篇
  1996年   40010篇
  1995年   38324篇
  1994年   35724篇
  1993年   33544篇
  1992年   121580篇
  1991年   118614篇
  1990年   115268篇
  1989年   111044篇
  1988年   102928篇
  1987年   101069篇
  1986年   95424篇
  1985年   91694篇
  1984年   69245篇
  1983年   59082篇
  1982年   35785篇
  1981年   32035篇
  1979年   64958篇
  1978年   46076篇
  1977年   38664篇
  1976年   36867篇
  1975年   39074篇
  1974年   47647篇
  1973年   45363篇
  1972年   42872篇
  1971年   40118篇
  1970年   37351篇
  1969年   35151篇
  1968年   32283篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Background The impact of various breast-cancer treatments on patients with a BRCA2 mutation has not been studied. We sought to estimate the impact of bilateral oophorectomy and other treatments on breast cancer-specific survival among patients with a germline BRCA2 mutation.Methods We identified 664 women with stage I–III breast cancer and a BRCA2 mutation by combining five different datasets (retrospective and prospective). Subjects were followed for 7.2 years from diagnosis to death from breast cancer. Tumour characteristics and cancer treatments were patient-reported and derived from medical records. Predictors of survival were determined using Cox proportional hazard models, adjusted for other treatments and for prognostic features.Results The 10-year breast-cancer survival for ER-positive patients was 78.9% and for ER-negative patients was 82.3% (adjusted HR = 1.23 (95% CI, 0.62–2.45, p = 0.55)). The 10-year breast-cancer survival for women who had a bilateral oophorectomy was 89.1% and for women who did not have an oophorectomy was 59.0% (adjusted HR = 0.45; 95% CI, 0.28–0.72, p = 0.001). The adjusted hazard ratio for chemotherapy was 0.83 (95% CI, 0.65–1.53: p = 0.56).Conclusions For women with breast cancer and a germline BRCA2 mutation, positive ER status does not predict superior survival. Oophorectomy is associated with a reduced risk of death from breast cancer and should be considered in the treatment plan.Subject terms: Targeted therapies, Breast cancer  相似文献   
32.
ABSTRACT

This study focused on factors associated with antiretroviral therapy (ART) adherence and quality of life among transgenderwomen in Sao Paulo, Brazil, using univariable and adjusted analysis. Adherence was evaluated with a self-report tool and with HIV viral load (VL) measurement. PROQOL-HIV was used to assess quality of life. 106 TGW with median 41 years old were included; most were white (56%) and had >10 years of education (57%). Median time since HIV/AIDS diagnosis was 10 years. Overall, participants had high T CD4+ counts (median 659 cells/mm3) and most (75%) had undetectable HIV VL. 85% were considered adherent using self-report (95%CI 77-91), whereas 72% (95%CI 62-80) were considered adherent when self-report and undetectable HIV VL were analyzed jointly. Older age was associated with higher ART adherence; each year increase in age was associated with 5% higher odds of adherence (p?=?0.021). Quality of life ranged from good-excellent in 5 of 8 domains. Younger age, lower education, higher time since HIV diagnosis, comorbidities, illicit drugs use and depression were associated with lower PROQOL scores in specific domains in univariable analysis, while depression was also associated with lower total PROQOL score even after adjustment for age, comorbidities and time since HIV diagnosis (p?=?0.048).  相似文献   
33.
PurposeTo retrospectively report on safety, pain relief and local tumor control achieved with percutaneous ablation of sacral bone metastases.Materials and methodsFrom February 2009 to June 2020, 23 consecutive patients (12 women and 11 men; mean age, 60 ± 8 [SD] years; median, 60; range: 48-80 years) with 23 sacral metastases underwent radiofrequency (RFA) or cryo-ablation (CA), with palliative or curative intent at our institution. Patients’ demographics and data pertaining to treated metastases, procedure-related variables, safety, and clinical evolution following ablation were collected and analyzed. Pain was assessed with numerical pain rating scale (NPRS).ResultsSixteen (70%) patients were treated with palliative and 7 (30%) with curative intent. Mean tumor diameter was 38 ± 19 (SD) mm (median, 36; range: 11-76). External radiation therapy had been performed on five metastases (5/23; 22%) prior to ablation. RFA was used in 9 (39%) metastases and CA in the remaining 14 (61%). Thermo-protective measures and adjuvant bone consolidation were used whilst treating 20 (87%) and 8 (35%) metastases, respectively. Five (22%) minor complications were recorded. At mean 31 ± 21 (SD) (median, 32; range: 2-70) months follow-up mean NPRS was 2 ± 2 (SD) (median, 1; range: 0–6) vs. 5 ± 1 (median, 5; range: 4–8; P < 0.001) at the baseline. Three metastases out of 7 (43%) undergoing curative ablation showed local progression at mean 4 ± 4 (SD) (median, 2; range: 1-8) months follow-up.ConclusionPercutaneous ablation of sacral metastases is safe and results in significant long-lasting pain relief. Local tumor control seems sub-optimal; however, further investigations are needed to confirm these findings due to paucity of data.  相似文献   
34.
AimsSelf-expanding metal stents provide rapid improvement of dysphagia in oesophageal cancer but are associated with complications. The aim of the present study was to test the effectiveness of an alternative treatment of combining biodegradable stents with radiotherapy.Materials and methodsA Simon two-stage single-arm prospective phase II trial design was used to determine the efficacy of biodegradable stents plus radiotherapy in patients with dysphagia caused by oesophagus cancer who were unsuitable for radical treatment. Fourteen patients were recruited and data from 12 were included in the final analyses.ResultsFive of 12 patients met the primary end point: one stent-related patient death; four further interventions for dysphagia within 16 weeks of stenting (41.7%, 95% confidence interval 15.2–72.3%). The median time to a 10-point deterioration of quality of life was 2.7 weeks. Nine patients died within 52 weeks of registration. The median time to death from any cause was 15.0 weeks (95% confidence interval 9.6–not reached).ConclusionThe high re-intervention observed, which met the pre-defined early stopping criteria, meant that the suggested alternative treatment was not sufficiently effective to be considered for a larger scale trial design. Further work is needed to define the place of biodegradable stents in the management of malignant oesophageal strictures.  相似文献   
35.
36.
ABSTRACT

Expeditious linkage and consistent engagement in medical care is important for people with HIV’s (PWH) health. One theory on fostering linkage and engagement involves HIV status disclosure to mobilize social support. To assess disclosure and social support’s association with linkage and engagement, we conducted a qualitative study sampling black and Latino men who have sex with men (MSM of color) in the U.S. Participants' narratives presented mixed results. For instance, several participants who reported delaying, inconsistent access, or detachment from care also reported disclosing for support purposes, yet sporadic engagement suggests that their disclosure or any subsequent social support have not assisted. The findings contribute to the literature that questions disclosure and social support’s influence on care engagement, especially when decontextualized from circumstances and intentions. Our findings suggest the mechanics of disclosure and social support require planned implementation if intending to affect outcomes, especially among MSM of color. From the findings, we explore steps that may bolster interventions seeking to anchor medical care engagement.  相似文献   
37.

Background

Nursing Home Compare (NHC) ratings, created and maintained by Medicare, are used by both hospitals and consumers to aid in the skilled nursing facility (SNF) selection process. To date, no studies have linked NHC ratings to actual episode-based outcomes. The purpose of this study was to evaluate whether NHC ratings are valid predictors of 90-day complications, readmission, and bundle costs for patients discharged to an SNF after primary total joint arthroplasty (TJA).

Methods

All SNF-discharged primary TJA cases in 2017 at a multihospital academic health system were queried. Demographic, psychosocial, and clinical variables were manually extracted from the health record. Medicare NHC ratings were then collected for each SNF. For patients in the Medicare bundle, postacute and total bundle cost was extracted from claims.

Results

Four hundred eighty-eight patients were discharged to a total of 105 unique SNFs. In multivariate analysis, overall NHC rating was not predictive of 90-day readmission/major complications, >75th percentile postacute cost, or 90-day bundle cost exceeding the target price. SNF health inspection and quality measure ratings were also not predictive of 90-day readmission/major complications or bundle performance. A higher SNF staffing rating was independently associated with a decreased odds for >75th percentile 90-day postacute spend (odds ratio, 0.58; P = .01) and a 90-day bundle cost exceeding the target price (odds ratio = 0.69; P = .02) but was similarly not predictive of 90-day readmission/complications.

Conclusion

Results of our study suggest that Medicare's NHC tool is not a useful predictor of 90-day costs, complications, or readmissions for SNFs within our health system.  相似文献   
38.
39.

Objective

The frailty index has been linked to adverse outcomes after surgical procedures. In this study, we evaluated the association between frailty index and outcomes after elective lower extremity bypass (LEB) for lower extremity ischemia.

Methods

The American College of Surgeons National Surgical Quality Improvement Program data set (2005-2012) was used to identify patients who underwent elective LEB using diagnostic and procedure Current Procedural Terminology codes. Modified frailty index (mFI) scores, derived from the Canadian Study of Health and Aging, were categorized into three groups: low, medium, and high. Association of mFI with 30-day postoperative death (POD), myocardial infarction (MI), cardiopulmonary events (CPEs), deep tissue surgical site infection (SSI), and graft failure (GF) was evaluated. Both univariate and multivariable regression analyses—adjusted for age, sex, American Society of Anesthesiologists class, body mass index, and creatinine levels—were used to assess the effect of frailty on each outcome.

Results

Of 12,677 patients (mean age, 67.7 ± 11.1 years) identified who underwent elective LEB, POD occurred in 265 (2.1% overall). Postoperative MI, SSI, CPEs, and GF occurred in 1.6%, 2.5%, 3.1%, and 4.3%, respectively. The mean mFI of the entire sample was 0.3 ± 0.1. Adjusted odds ratio for development of any morbidity in the group with the highest mFI was 1.36 (95% confidence interval, 1.08-1.72; P = .010) compared with the low frailty group. Patients with higher mFI were more likely to develop MI and CPEs but not SSI or GF. Univariate and multivariable analyses showed a significantly increased risk of POD among those in the highest mFI tertile. Female sex and age, increased American Society of Anesthesiologists class and creatinine levels, and decreased body mass index independently predicted increased mortality. The addition of categorical mFI improved models with these variables.

Conclusions

Higher mFI is independently associated with higher mortality and morbidity. Preoperative mFI assessment may be considered an additional screening tool for risk stratification among patients undergoing LEB.  相似文献   
40.

Background

We hypothesized that trends in total bilirubin in the context of cholecystitis and symptomatic cholelithiasis could be used to guide testing for the presence of common bile duct stones (CBDS).

Methods

A review of adult patients with acute cholecystitis or biliary colic with elevated total bilirubin and at least two levels drawn prior to procedural intervention was performed. Trends of total bilirubin and other serum makers were examined to predict the presence of CBDS.

Results

The total bilirubin level at presentation, average over 24?h and average over 48?h (3.74?mg/dl vs. 2.29?mg/dl, p?=?0.005; 3.72?mg/dl vs. 2.40?mg/dl, p?=?0.009; 2.41?mg/dl vs. 1.47?mg/dl, p?<?0.001) respectively, were all higher in those with CBDS. However, prediction was not improved by following levels over time.

Conclusion

Patients presenting with elevated serum bilirubin, should undergo immediate imaging or procedural intervention rather than obtaining follow-up bilirubin levels.  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