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   18268篇
  免费   1498篇
  国内免费   38篇
耳鼻咽喉   128篇
儿科学   694篇
妇产科学   534篇
基础医学   2362篇
口腔科学   229篇
临床医学   2056篇
内科学   3442篇
皮肤病学   317篇
神经病学   1980篇
特种医学   301篇
外国民族医学   5篇
外科学   1959篇
综合类   146篇
一般理论   67篇
预防医学   2762篇
眼科学   265篇
药学   1161篇
  1篇
中国医学   38篇
肿瘤学   1357篇
  2024年   43篇
  2023年   281篇
  2022年   486篇
  2021年   912篇
  2020年   552篇
  2019年   756篇
  2018年   861篇
  2017年   614篇
  2016年   630篇
  2015年   698篇
  2014年   907篇
  2013年   1155篇
  2012年   1598篇
  2011年   1613篇
  2010年   824篇
  2009年   669篇
  2008年   1137篇
  2007年   1203篇
  2006年   965篇
  2005年   899篇
  2004年   813篇
  2003年   728篇
  2002年   537篇
  2001年   76篇
  2000年   63篇
  1999年   66篇
  1998年   117篇
  1997年   75篇
  1996年   43篇
  1995年   48篇
  1994年   40篇
  1993年   39篇
  1992年   30篇
  1991年   18篇
  1990年   17篇
  1989年   22篇
  1987年   12篇
  1986年   16篇
  1985年   17篇
  1984年   16篇
  1982年   10篇
  1981年   16篇
  1980年   13篇
  1977年   11篇
  1976年   7篇
  1975年   8篇
  1974年   11篇
  1971年   7篇
  1970年   8篇
  1962年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.

Background

When retained hemothorax occurs, video-assisted thoracoscopy or thoracotomy is performed, but recently, tissue plasminogen activator (tPA) has been used. This study evaluated intrapleural tPA use for retained traumatic hemothoraces.

Methods

A retrospective review was conducted of trauma patients treated with intrapleural tPA for retained hemothorax. Data included demographics, past medical and surgical histories, injury details, treatment details, and outcomes.

Results

Seven patients (median age = 47 years, male = 6, blunt trauma = 6) met study criteria. All patients received a chest tube. Six patients later received computed tomography-guided drains for tPA infusion. Number of tPA treatments per patient varied from 1 to 5. Median total tPA dosage was 24 mg. Median time from injury to chest tube placement was 11 days and from chest tube placement to first tPA treatment was 4 days. No patients required a video-assisted thoracoscopy; however, 1 patient required thoracotomy. There were no deaths or bleeding complications attributed to intrapleural tPA.

Conclusion

Although future studies are needed to identify optimum treatment guidelines, intrapleural tPA appears to be a safe and efficacious treatment option.  相似文献   
142.
143.

Introduction

Free intra-peritoneal air in blunt trauma is a classic sign associated with hollow viscus injury, traditionally mandating laparotomy. In blunt abdominal trauma, the CT scan has become the diagnostic modality of choice. The increased sensitivity of CT scans may lead to detection of free intra-peritoneal air that is not clinically significant.

Objective

To characterize conditions and findings that allow for the safe observation of blunt trauma patients with free air and to propose a patient management algorithm to decrease rates of non-therapeutic laparotomy.

Design

A retrospective review of 5877 blunt trauma patients who had an abdominal CT scan upon admission to our hospital from 2003 to 2011. A secondary CT review was performed by a single radiologist to further characterize the CT findings in the 74 patients with free air reported on initial scan. Management and hospital course were reviewed in these patients.

Results

Of the 74 patients with intra-abdominal free air, 36 patients with a benign clinical picture were observed and 38 patients underwent urgent exploratory laparotomy. Eleven patients received a non-therapeutic laparotomy. The majority (61%) of patients, 45 of 74, had free air and no significant injury suggesting the presence of benign free air. Patients who had intra-abdominal injury also typically had other clinical or radiologic signs of injury. Findings that were highly predictive of intra-abdominal injury in the setting of free air were free fluid (P < 0.001), radiographic signs of bowel trauma (P < 0.001) as well as clinical and/or radiographic seatbelt sign (P = 0.004).

Conclusions

CT scans may detect free air that is not always clinically significant. Free fluid, seatbelt sign or radiographic signs of bowel trauma in the presence of pneumoperitoneum is highly predictive of injury and these patients should be explored. Based on the results of our study, we created an algorithm to aid in identifying those patients with intra-abdominal free air who may be observed safely.  相似文献   
144.

Background

Subglottic stenosis (SGS) is the most common congenital and/or acquired laryngotracheal anomaly requiring tracheotomy in infants. We sought to determine factors associated with a greater likelihood of tracheotomy in symptomatic infants with SGS who underwent laryngotracheoplasty (LTP).

Methods

Retrospective case series with chart review of patients undergoing single-stage LTP for SGS over a 10-year period (2001–2010) in a tertiary-care pediatric hospital.

Results

Twenty-two children (15 boys, 7 girls), with a mean gestational age of 32.5 weeks, underwent LTP with and without interpositional grafting, at a median age of 89 days. Ten patients (43%) required postoperative tracheotomy. Of patients weighing < 2.5 kg, 7 of 8 eventually required tracheotomy, while none weighing > 5 kg needed tracheotomy (p = 0.003). The average length of stay for patients with a tracheotomy was 125 days, while those without tracheotomy required only 58 days (p = 0.011). The grade of SGS (p = 0.809), gender (p = 0.968), age at surgery (p = 0.178), and gestational age (p = 0.117) were not significantly associated with the need for tracheotomy. Weight at surgery was significantly correlated with the likelihood of needing tracheotomy (p = 0.003).

Conclusions

Patients who weighed less than 2.5 kg at the time of LTP procedures were more likely to require a postoperative tracheotomy. Children who required tracheotomy had longer lengths of hospital stay.  相似文献   
145.

Introduction

Several approaches have been taken to reduce pre-antiretroviral therapy (ART) losses between HIV testing and ART initiation in low- and middle-income countries, but a systematic assessment of the evidence has not yet been undertaken. The aim of this systematic review is to assess the potential for interventions to improve or facilitate linkage to or retention in pre-ART care and initiation of ART in low- and middle-income settings.

Methods

An electronic search was conducted on Medline, Embase, Global Health, Web of Science and conference databases to identify studies describing interventions aimed at improving linkage to or retention in pre-ART care or initiation of ART. Additional searches were conducted to identify on-going trials on this topic, and experts in the field were contacted. An assessment of the risk of bias was conducted. Interventions were categorized according to key domains in the existing literature.

Results

A total of 11,129 potentially relevant citations were identified, of which 24 were eligible for inclusion, with the majority (n=21) from sub-Saharan Africa. In addition, 15 on-going trials were identified. The most common interventions described under key domains included: health system interventions (i.e. integration in the setting of antenatal care); patient convenience and accessibility (i.e. point-of-care CD4 count (POC) testing with immediate results, home-based ART initiation); behaviour interventions and peer support (i.e. improved communication, patient referral and education) and incentives (i.e. food support). Several interventions showed favourable outcomes: integration of care and peer supporters increased enrolment into HIV care, medical incentives increased pre-ART retention, POC CD4 testing and food incentives increased completion of ART eligibility screening and ART initiation. Most studies focused on the general adult patient population or pregnant women. The majority of published studies were observational cohort studies, subject to an unclear risk of bias.

Conclusions

Findings suggest that streamlining services to minimize patient visits, providing adequate medical and peer support, and providing incentives may decrease attrition, but the quality of the current evidence base is low. Few studies have investigated combined interventions, or assessed the impact of interventions across the HIV cascade. Results from on-going trials investigating POC CD4 count testing, patient navigation, rapid ART initiation and mobile phone technology may fill the quality of evidence gap. Further high-quality studies on key population groups are required, with interventions informed by previously reported barriers to care.  相似文献   
146.
Complement C3 activation is a characteristic finding in membranoproliferative GN (MPGN). This activation can be caused by immune complex deposition or an acquired or inherited defect in complement regulation. Deficiency of complement factor H has long been associated with MPGN. More recently, heterozygous genetic variants have been reported in sporadic cases of MPGN, although their functional significance has not been assessed. We describe a family with MPGN and acquired partial lipodystrophy. Although C3 nephritic factor was shown in family members with acquired partial lipodystrophy, it did not segregate with the renal phenotype. Genetic analysis revealed a novel heterozygous mutation in complement factor H (R83S) in addition to known risk polymorphisms carried by individuals with MPGN. Patients with MPGN had normal levels of factor H, and structural analysis of the mutant revealed only subtle alterations. However, functional analysis revealed profoundly reduced C3b binding, cofactor activity, and decay accelerating activity leading to loss of regulation of the alternative pathway. In summary, this family showed a confluence of common and rare functionally significant genetic risk factors causing disease. Data from our analysis of these factors highlight the role of the alternative pathway of complement in MPGN.  相似文献   
147.
Nipple‐sparing mastectomy (NSM) is an increasingly utilized surgical option in managing breast carcinoma; however, data on malignant involvement of a separately submitted nipple margin are scant. Consecutive NSM, including those performed for therapeutic and prophylactic purposes, over a 4‐year period (2007–2011), were studied. A separately submitted nipple margin was evaluated by permanent H&E preparations and via frozen section evaluation whenever requested. 325 consecutive NSM specimens, 208 (64%) therapeutic‐NSM, and 117 (36%) prophylactic‐NSM were studied. All nipples were clinically unremarkable. 86% (179/208) of nipple margins from therapeutic‐NSM and 100% (117/117) from prophylactic‐NSM showed no histopathologic abnormality. 14% (29/208) of nipple margins from therapeutic‐NSM and no nipple margin from prophylactic‐NSM showed malignancy. Frozen section evaluation was performed in 188/325 NSM (58%) with a sensitivity of 64% and specificity of 99%. Central tumor location and stage N2/N3 lymph node status were significantly associated with nipple margin positivity (χ2 ≤ 0.05). Subsequent nipple resection was performed in 69% (20/29) of nipple margin‐positive cases with residual malignancy found in 40% (8/20, including three cases of invasive carcinoma). In a mean follow‐up of 33 months, one invasive carcinoma recurred in the “saved” nipple, 36 months after therapeutic‐NSM. 14% (29/208) of nipple margins in therapeutic‐NSM and no nipple margin (0/117) in prophylactic‐NSM showed malignancy. Central tumor location and N2/N3 stage were significantly associated with nipple margin positivity (χ2 ≤ 0.05).  相似文献   
148.
This retrospective cohort study evaluates the effect of chronic antimicrobial suppression (CAS) therapy on clinical outcomes in patients with continuous‐flow left ventricular assist devices (CF‐LVADs) and a history of device‐related infection. Patients with CF‐LVAD implantation between January 2008 and August 2011 who received systemic CAS after index antibiotic treatment of a device‐related infection were included. Chronic suppression was defined as continuation of antibiotics for longer than 6 weeks after the index infection. Standard International Society for Heart and Lung Transplantation definitions were used. The primary outcome is failure of CAS, defined as a clinical deterioration resulting in the need for transition from oral to intravenous (IV) therapy or a need to change to a different IV antibiotic, elevation to status 1A on the transplant list as a result of ongoing infection, or device/driveline exchange. Of 140 patients screened, 16 patients were included (69% male, 63% African American, median age 52 years). The driveline was the most common site of infection (69%). Organisms isolated included Gram‐positive cocci (n = 7), Gram‐negative bacilli (n = 10), and Candida (n = 1). Oral trimethoprim/sulfamethoxazole treatment was most commonly used for suppression (37.5%). Failure of CAS occurred in 5/16 (31%) patients after a mean time of 175 days on therapy (range 10–598). The majority of failures (60%) required device exchanges. Side effects of nausea, vomiting, or diarrhea were reported in three patients; all required changes in oral suppression regimen. Clostridium difficile infection was noted in two patients. These results, which must be confirmed by a larger analysis, suggest that one‐third of CF‐LVAD patients may develop recurrent infections while on CAS therapy.  相似文献   
149.
To help decrease mortality on the liver transplant waitlist, transplant centers are using living donors (LD) and high‐risk donors (HRD) in addition to standard‐risk donors (SRD). HRD is defined as having a donor risk index score higher than 1.6, which suggests a great risk of graft failure. Recent studies have examined survival rates between HRD and SRD recipients; however, little is known about outcomes other than survival, specifically psychosocial outcomes. The purpose of this preliminary, prospective study was to compare post‐transplant psychosocial and recovery outcomes between SRD and LD and HRD liver recipients. These outcomes include cognitive functioning, psychological distress, quality of life, and self‐reported and objective measures of recovery. Eighty‐four patients provided baseline and six‐month post‐transplant data. There were generally no statistically significant differences at baseline or the six‐month follow‐up, suggesting that patients receiving HRD livers have similar outcomes to those who receive SRD livers. However, some effect sizes suggest potential advantages for LD recipients compared to SRD recipients. Transplant centers may be more willing to encourage patients to accept HRD or LD livers knowing that they may have comparable outcomes to SRD recipients, which also has implications for the transplant waitlist.  相似文献   
150.

Purpose

We evaluated factors influencing re-operation in tension band and plating of isolated olecranon fractures.

Methods

Four hundred eighty-nine patients with isolated olecranon fractures who underwent tension band (TB) or open reduction internal fixation (ORIF) from 2003 to 2013 were identified at an urban level 1 trauma centre. Medical records were reviewed for patient information and complications, including infection, nonunion, malunion, loss of function or hardware complication requiring an unplanned surgical intervention. Electronic radiographs of these patients were reviewed to identify Orthopaedic Trauma Association (OTA) fracture classification and patients who underwent TB or ORIF.

Results

One hundred seventy-seven patients met inclusion criteria of isolated olecranon fractures. TB was used for fixation in 43 patients and ORIF in 134. No statistical significance was found when comparing complication rates in open versus closed olecranon fractures. In a multivariate analysis, the key factor in outcome was method of fixation. Overall, there were higher rates of infection and hardware removal in the TB compared with the ORIF group.

Conclusions

Our results demonstrate that the dominant factor driving re-operation in isolated olecranon fractures is type of fixation. When controlling for all variables, there is an increased chance of re-operation in patients with TB fixation.  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