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   5179篇
  免费   453篇
  国内免费   18篇
耳鼻咽喉   106篇
儿科学   252篇
妇产科学   111篇
基础医学   602篇
口腔科学   57篇
临床医学   559篇
内科学   912篇
皮肤病学   58篇
神经病学   393篇
特种医学   445篇
外科学   683篇
综合类   101篇
一般理论   4篇
预防医学   477篇
眼科学   83篇
药学   289篇
中国医学   8篇
肿瘤学   510篇
  2021年   76篇
  2020年   48篇
  2019年   105篇
  2018年   99篇
  2017年   73篇
  2016年   59篇
  2015年   78篇
  2014年   121篇
  2013年   172篇
  2012年   241篇
  2011年   232篇
  2010年   122篇
  2009年   120篇
  2008年   206篇
  2007年   219篇
  2006年   187篇
  2005年   219篇
  2004年   208篇
  2003年   163篇
  2002年   181篇
  2001年   182篇
  2000年   165篇
  1999年   147篇
  1998年   98篇
  1997年   82篇
  1996年   61篇
  1995年   61篇
  1994年   56篇
  1993年   59篇
  1992年   121篇
  1991年   110篇
  1990年   127篇
  1989年   154篇
  1988年   134篇
  1987年   127篇
  1986年   116篇
  1985年   112篇
  1984年   83篇
  1983年   64篇
  1982年   45篇
  1981年   42篇
  1980年   41篇
  1979年   57篇
  1978年   45篇
  1977年   40篇
  1976年   40篇
  1974年   33篇
  1973年   30篇
  1972年   39篇
  1971年   29篇
排序方式: 共有5650条查询结果,搜索用时 15 毫秒
1.

Objectives

Expedient extubation after cardiac surgery has been associated with improved outcomes, leading to postoperative extubation frequently during overnight hours. However, recent evidence in a mixed medical-surgical intensive care unit population demonstrated worse outcomes with overnight extubation. This study investigated the impact of overnight extubation in a statewide, multicenter Society of Thoracic Surgeons database.

Methods

Records from 39,812 patients undergoing coronary artery bypass grafting or valve operations (2008-2016) and extubated within 24 hours were stratified according to extubation time between 06:00 and 18:00 (day) or between 18:00 and 6:00 (overnight). Outcomes including reintubation, mortality, and composite morbidity-mortality were evaluated using hierarchical regression models adjusted for Society of Thoracic Surgeons predictive risk scores. To further analyze extubation during the night, a subanalysis stratified patients into 3 groups: 06:00 to 18:00, 18:00 to 24:00, and 24:00 to 06:00.

Results

A total of 20,758 patients were extubated overnight (52.1%) and were slightly older (median age 66 vs 65 years, P < .001) with a longer duration of ventilation (4 vs 7 hours, P < .001). Day and overnight extubation were associated with equivalent operative mortality (1.7% vs 1.7%, P = .880), reintubation (3.7% vs 3.4%, P = .141), and composite morbidity-mortality (8.2% vs 8.0%, P = .314). After risk adjustment, overnight extubation was not associated with any difference in reintubation, mortality, or composite morbidity-mortality. On subanalysis, those extubated between 24:00 and 06:00 exhibited increased composite morbidity-mortality (odds ratio, 1.18; P = .001) but no difference in reintubation or mortality.

Conclusions

Extubation overnight was not associated with increased mortality or reintubation. These results suggest that in the appropriate clinical setting, it is safe to routinely extubate cardiac surgery patients overnight.  相似文献   
2.
Behçet disease is a complex, multisystem disease characterized by recurrent oral and genital ulcerations. It rarely occurs in infants or children. Neonatal Behçet disease has been reported in infants whose ulcers resolve at or before 9 weeks of age. Few cases of neonatal Behçet disease persisting into childhood have previously been reported. We report the case of a 1‐month‐old infant who presented with severe recurrent genital ulcerations and at 6 months developed recurrent oral ulcerations. Her orogenital ulcerations continue to recur. Human leukocyte antigen testing revealed HLA‐B51 and B44 positivity. This is a case of pediatric Behçet disease in the neonatal period. Behçet disease should be considered in the differential diagnosis of recurrent genital and oral ulcerations in infants and children.  相似文献   
3.
4.
Background: While over half of stroke survivors recover the ability to walk without assistance, deficits persist in the performance of walking adaptations necessary for safe home and community mobility. One such adaptation is the ability to walk or step backward. Post-stroke rehabilitation rarely includes backward walking (BW) assessment and BW deficits have not been quantified in post-stroke community ambulators.

Objective: To quantify spatiotemporal and kinematic BW characteristics in post-stroke community ambulators and compare their performance to controls.

Methods: Individuals post-stroke (n = 15, 60.1 ± 12.9 years, forward speed: 1.13 ± 0.23 m/s) and healthy adults (n = 12, 61.2 ± 16.2 years, forward speed: 1.40 ± 0.13 m/s) performed forward walking (FW) and BW during a single session. Step characteristics and peak lower extremity joint angles were extracted using 3D motion analysis and analyzed with mixed-method ANOVAs (group, walking condition).

Results: The stroke group demonstrated greater reductions in speed, step length and cadence and a greater increase in double-support time during BW compared to FW (p < .01). Compared to FW, the post-stroke group demonstrated greater reductions in hip extension and knee flexion during BW (p < .05). The control group demonstrated decreased plantarflexion and increased dorsiflexion during BW, but these increases were attenuated in the post-stroke group (p < .05).

Conclusions: Assessment of BW can unmask post-stroke walking impairments not detected during typical FW. BW impairments may contribute to the mobility difficulties reported by adults post-stroke. Therefore, BW should be assessed when determining readiness for home and community ambulation.  相似文献   

5.
6.
The purpose of this study was to evaluate a new fluorescence polarization immunoassay, TDx, for digitoxin by comparing the results of this assay with those of a radioimmunoassay (RIA). Thirty-three serum samples were obtained from 15 patients during, and for 4 weeks after, a 4-week course of digitoxin therapy. Each sample was separated by centrifugation, coded, and frozen until analysis. At the time of analysis, each sample was divided and analyzed simultaneously by TDx and RIA. Nine samples yielded results less than 2 ng/ml (limit of assay sensitivity) by one or both methods and were excluded from further data analysis. Linear regression analysis of the results of the remaining 24 paired samples (x = TDx, y = RIA) revealed a strong correlation coefficient of r2 = 0.95, slope = 0.95, and a y intercept of -0.99 (y = -0.99 + 0.95x). Additionally, the TDx results were lower than the RIA values in only five of 33 paired samples; and these occurred in four patients who had a significantly lower mean estimated creatinine clearance than that of the other 11 patients (39.0 +/- 9.1 ml/min/1.73 m2 vs. 63.3 +/- 11.8 ml/min/1.73 m2, p less than 0.01). The TDx system is a comparable alternative to the RIA method, but differences in specificity and sensitivity may exist and should be evaluated more thoroughly.  相似文献   
7.
Neutropenic enterocolitis in adults with acute leukemia   总被引:2,自引:0,他引:2  
Neutropenic enterocolitis has been previously described only by case reports and literature reviews. Of 499 adults with acute leukemia seen over a 23-year period (1962 to 1985), 13 cases (2.6%) of neutropenic enterocolitis have been reported. Eleven of these 13 patients were profoundly neutropenic (mean white blood cell count, 472/cu mm) and developed abdominal symptoms during either initial induction or relapse of acute leukemia. Histologic confirmation was available in ten cases, five cases after surgical resection and five cases at autopsy after nonoperative management. Three patients with isolated ileocecal inflammation without infarction at the time of surgery were successfully managed without resection. Five patients treated with surgery died four to 64 weeks postoperatively (mean survival, 21.6 weeks) of nonsurgical complications of leukemia. Three patients were still alive, one patient 42 months after right hemicolectomy and two patients five months after exploration only. All five patients managed medically died an average of 1.4 days (range, zero to four days) after the onset of abdominal pain. Survival in patients with acute leukemia who develop neutropenic enterocolitis is determined by early recognition and appropriate surgical exploration that can be expected to yield an acceptable operative mortality.  相似文献   
8.
9.
10.
Acute airway management. Role of cricothyroidotomy   总被引:1,自引:0,他引:1  
Thirty-four cases of emergency cricothyroidotomy performed formed from September 1984 through January 1988 are reviewed. Thirty-one of the cases were required out of 2,200 acute-trauma patients. The indication for cricothyroidotomy was inability to establish an airway by intubation usually in a situation of possible neck injury or severe facial trauma. Fourteen of the patients died as a result of their injuries, 13 of these in the first several hours after injury. The 20 surviving patients are studied in two groups: eleven patients whose cricothyroidotomy remained in place until decannulation (group I) and nine patients who underwent tracheostomy subsequent to cricothyroidotomy (group II). Clinical follow-up included physical examination in all survivors and endoscopic evaluation in twelve patients. Three minor complications were discovered in each of the two groups and two major complications were noted in group II. The major complications included a case of tracheal stomal stenosis requiring tracheal resection and a case of partially obstructing tracheal granulation tissue requiring endoscopic resection. This study supports the use of emergency cricothyroidotomy in situations in which intubation is not successful or thought to be safe. Data is also presented that suggests that tracheostomy subsequent to emergency cricothyroidotomy does not necessarily reduce airway-related morbidity in these patients.  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