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   971篇
  免费   81篇
  国内免费   2篇
耳鼻咽喉   2篇
儿科学   31篇
妇产科学   11篇
基础医学   122篇
口腔科学   10篇
临床医学   189篇
内科学   253篇
皮肤病学   5篇
神经病学   66篇
特种医学   21篇
外科学   105篇
综合类   3篇
一般理论   2篇
预防医学   139篇
眼科学   16篇
药学   61篇
肿瘤学   18篇
  2023年   12篇
  2022年   13篇
  2021年   44篇
  2020年   16篇
  2019年   36篇
  2018年   27篇
  2017年   23篇
  2016年   39篇
  2015年   22篇
  2014年   32篇
  2013年   43篇
  2012年   110篇
  2011年   94篇
  2010年   32篇
  2009年   38篇
  2008年   53篇
  2007年   44篇
  2006年   40篇
  2005年   38篇
  2004年   39篇
  2003年   32篇
  2002年   28篇
  2001年   15篇
  2000年   26篇
  1999年   16篇
  1998年   14篇
  1997年   9篇
  1996年   3篇
  1995年   4篇
  1994年   3篇
  1992年   13篇
  1991年   14篇
  1990年   12篇
  1989年   8篇
  1988年   6篇
  1987年   6篇
  1986年   6篇
  1985年   8篇
  1984年   5篇
  1983年   4篇
  1982年   2篇
  1981年   4篇
  1980年   4篇
  1979年   2篇
  1978年   3篇
  1977年   3篇
  1974年   2篇
  1973年   3篇
  1971年   1篇
  1960年   1篇
排序方式: 共有1054条查询结果,搜索用时 390 毫秒
61.
Transesophageal echocardiography (TEE) is a monitoring and diagnostic tool for the care of children undergoing cardiac surgery. We analyzed reports from 865 routine TEE examinations performed between January 1994 and March 2002 in patients younger than 17-yr-old who were undergoing surgery for congenital heart disease. Patients' median age was 36 mo (range, 1 day-16 yr). The primary end-point of the study was the incidence of surgical and medical management decisions changed as a result of TEE findings; secondary end-points were diagnostic impact (diagnostic exclusions and new diagnoses) and surgical outcome. Fifty percent of the examinations were performed by anesthesiologists with an advanced level of training in perioperative TEE; all of the examiners had an experience of >or=>500 TEE examinations. Supervision by an anesthesiologist with an advanced level of training was requested in 36.7% of cases; supervision by a cardiologist was requested in 3.8%. Surgical alterations of management were reported in 12.7% of cases and included the need for a repeat bypass run in 7.3%; medical alterations of management were required in 19.4% of cases. We observed a diagnostic impact of TEE in 18.5% of cases and a suboptimal but acceptable surgical outcome in 27.6%; TEE findings predicted postoperative difficulties in 4.0%. Our results confirm the utility of routine TEE to assess repair of congenital heart defects. Furthermore, this service was competently performed by a regular team of cardiac anesthesiologists appropriately trained in TEE. IMPLICATIONS: Transesophageal echocardiography (TEE) is an essential monitoring and diagnostic device for the care of children undergoing cardiac surgery. The surgical and medical impact of TEE is demonstrated in a large series of patients. This service can be performed by appropriately trained cardiac anesthesiologists.  相似文献   
62.
Bronchogenic cysts arise from an abnormal budding of the ventral diverticulum of the foregut or the tracheobronchial tree during embryogenesis. Rarely they develop within the pericardium. Symptoms of intrapericardial bronchogenic cysts such as chest pain, shortness of breath and arrhythmias can vary according to the location of the cyst, its size and compression of heart and vessels. In this case report we present a young women in whom the diagnosis of an intrapericardial bronchogenic cyst was made by echocardiography and later was approved intraoperatively.  相似文献   
63.
Transoesophageal echocardiography (TOE) has gained widespreadacceptance among cardiac anaesthetists as a tool to facilitateperi-operative decision-making. This observational study analysesthe impact of TOE and its inter-observer variability on intra-operativepatient management during cardiac and major vascular surgery.From June 1996 to December 1998, standardized reports were obtainedfrom 11 anaesthetists in 1891 adult cardiac and vascular surgerypatients undergoing routine biplane or multiplane TOE. Inter-observervariability and the difference between variables of interestwere tested using the chi-squared test or factorial analysisof variance as appropriate. TOE examinations were performedbefore and after the operation; 1673 (88.5%) patients underwentcardiopulmonary bypass (CPB), and 218 (11.5%) patients had surgerywithout CPB, including 42 (2.2%) coronary revascularizations.In 923 patients (49%), TOE provided additional information thatinfluenced the patient’s therapy. In 968 patients (51%),TOE had only minor or no impact on clinical decision-making.In two patients (0.10%) the scheduled operation was not performed,and in another two patients the TOE examination led to majorcomplications. Observer-dependent variables were: implicationsof TOE for intra-operative decision-making (P<0.0001), estimationof image quality (P<0.0001), pre-operative left ventricularfractional area change (FAC) (P=0.0026), difference betweenpre-operative FAC and post-operative FAC (P=0.033), and requestsfor supervision (P<0.0001). There was no significant differencein the case mix between observers. TOE had an important impacton intra-operative patient management. Inter-observer variabilitywas significant for several variables but not for the frequencyof additional surgical procedures. Br J Anaesth 2001; 86: 497–505  相似文献   
64.
65.
Background and Purpose. Rheumatoid arthritis frequently results in functional impairment. This study investigated the effect of a specific exercise regimen on function. Method. A randomized controlled assessor-blinded (N = 36) compared the effect of knee extensor and f lexor muscle training on pain, the timed up and go (TUG) test and the Health Assessment Questionnaire in subjects with non-acute rheumatoid arthritis. Results. Knee extensor and flexor muscle training increased isokinetic torques at speeds of 60°/sec?1 and 120°/sec?1 as measured by an isokinetic dynamometer (p = 0.02–0.003). The experimental group experienced a reduction in pain (p = 0.03), an improvement in TUG time (p = 0.01) and in function as measured by the Health Assessment Questionnaire (p = 0.04). Conclusions. Specific knee muscle training can be administered safely in people with non-acute rheumatoid arthritis, and may produce functional benefits.  相似文献   
66.
Abstract

In this prospective study a series of 89 patients with subarachnoid haemorrhage (SAH), most of whom had a “good” neurological outcome, were interviewed 10 weeks and 12 monts following their SAH about changes in psychosocial functioning since their SAH, and the presence of symptoms, such as excessive fatigue, that can influence psychosocial functioning. Information was also gathered from close relatives whenever possible. Data about a range of “SAH factors”, including site of aneurysm, patient clinical grade, and vasospasm, were also gathered at the time of hospitalisation, and subjects were graded according to the Glasgow Outcome Scale (GOS) at each follow-up assessment. Statistical analyses to see whether these factors were predictive of later psychosocial impairment were carried out. A high proportion of subjects demonstrated some mild to moderate psychosocial impairments at 10 weeks and, although recovery occurred in some areas over the next 8 months, 86% of subjects still suffered from excessive fatigue and 55% from hypersensitivity to noise at the 12-month assessment. Of the subjects who were employed at the time of their SAH and had a good neurological outcome, 59% were either unemployed or were working reduced hours at the 12-month follow-up. Overall the GOS was not sensitive to psychosocial impairment, as 87% of the subjects had a GOS of “1” at both 10 weeks and 12 months. The small number of subjects who demonstrated vasospasm or had a poor neurological grade on discharge from hospital and at follow-up were more likely to report changes in temperament, leisure activities, and social behaviour at follow-up.  相似文献   
67.
68.
OBJECTIVE: Moderate to severe irreversible mitral regurgitation secondary to myocardial infarction is an independent risk factor for reduced long-term survival. Late effects of correction of mitral incompetence concomitant with coronary artery bypass grafting (CABG) are less well known and the choice of mitral valve procedure is still debated. METHODS: From 1988 to 1998, 93 consecutive patients (mean age 63+/-9 years) were treated for moderate to severe irreversible mitral regurgitation secondary to myocardial infarction; 84 were in NYHA functional class III-IV and 19 were in cardiogenic shock. Thirty-seven patients underwent emergency surgery. Perioperative intraaortic balloon pump (IABP) was necessary in 33 patients. Follow-up ranged from 6 months to 12 years (mean 51 months+/-41). RESULTS: Mitral valve was repaired in 30 patients and replaced in 63. Replacement was preferably performed in patients with major displacement of papillary muscle and in patients with acute papillary muscle rupture. CABG (3.4 distal anastomoses) was performed in all patients and was complete in 92%. Early mortality was 15% (14/93). Multivariable analysis identified need for IABP (P=0.005) and COPD (P=0.02) as risk factors for early death. Emergency surgery had only a trend (P=0.15) for increased mortality; age, low ejection fraction, repair vs. replacement had no influence. Actuarial survival rates at 1, 5 and 10 years were 81, 65 and 56%, respectively. Late survival was similar in patients with replacement or repair (P=0.46). At last follow-up, all but one patient were in NYHA functional class I or II. CONCLUSIONS: Combined mitral valve procedure and myocardial revascularization, as complete as possible, for moderate to severe mitral regurgitation secondary to myocardial infarction achieve satisfactory early and late outcome despite the increased operative mortality. Acute papillary muscle rupture, severe restriction of the mitral valve by major displacement of the papillary muscle are better managed by valve replacement.  相似文献   
69.

Background

In pig‐to‐human xenotransplantation, interactions between human natural killer (NK) cells and porcine endothelial cells (pEC) are characterized by recruitment and cytotoxicity. Protection from xenogeneic NK cytotoxicity can be achieved in vitro by the expression of the non‐classical human leukocyte antigen‐E (HLA‐E) on pEC. Thus, the aim of this study was to analyze NK cell responses to vascularized xenografts using an ex vivo perfusion system of pig limbs with human blood.

Methods

Six pig forelimbs per group, respectively, stemming from either wild‐type (wt) or HLA‐E/hCD46 double‐transgenic (tg) animals, were perfused ex vivo with heparinized human blood for 12 hours. Blood samples were collected at defined time intervals, cell numbers counted, and peripheral blood mononuclear cells analyzed for phenotype by flow cytometry. Muscle biopsies were analyzed for NK cell infiltration. In vitro NK cytotoxicity assays were performed using pEC derived from wt and tg animals as target cells.

Results

Ex vivo, a strong reduction in circulating human CD45 leukocytes was observed after 60 minutes of xenoperfusion in both wt and tg limb groups. NK cell numbers dropped significantly. Within the first 10 minutes, the decrease in NK cells was more significant in the wt limb perfusions as compared to tg limbs. Immunohistology of biopsies taken after 12 hours showed less NK cell tissue infiltration in the tg limbs. In vitro, NK cytotoxicity against hCD46 single tg pEC and wt pEC was similar, while lysis of double tg HLA‐E/hCD46 pEC was significantly reduced. Finally, circulating cells of pig origin were observed during the ex vivo xenoperfusions. These cells expressed phenotypes mainly of monocytes, B and T lymphocytes, NK cells, as well as some activated endothelial cells.

Conclusions

Ex vivo perfusion of pig forelimbs using whole human blood represents a powerful tool to study humoral and early cell‐mediated rejection mechanisms of vascularized pig‐to‐human xenotransplantation, although there are several limitations of the model. Here, we show that (i) transgenic expression of HLA‐E/hCD46 in pig limbs provides partial protection from human NK cell‐mediated xeno responses and (ii) the emergence of a pig cell population during xenoperfusions with implications for the immunogenicity of xenografts.  相似文献   
70.

Purpose

Rupture-prone atherosclerotic plaques are characterized by accumulation of macrophages, which have shown to express somatostatin type 2 receptors. We aimed to investigate whether somatostatin receptor-targeting positron emission tomography (PET) tracers, [68Ga]DOTANOC, [18F]FDR-NOC, and [68Ga]DOTATATE, can detect inflamed atherosclerotic plaques.

Procedures

Atherosclerotic IGF-II/LDLR?/?ApoB100/100 mice were studied in vivo and ex vivo for tracer uptake into atherosclerotic plaques. Furthermore, [68Ga]DOTANOC and [68Ga]DOTATATE were compared in a head-to-head setting for in vivo PET/X-ray computed tomography (CT) imaging characteristics.

Results

Ex vivo uptake of [68Ga]DOTANOC and [68Ga]DOTATATE in the aorta was higher in atherosclerotic mice compared to control C57Bl/6N mice, while the aortic uptake of [18F]FDR-NOC showed no genotype difference. Unlike [18F]FDR-NOC, [68Ga]DOTANOC and [68Ga]DOTATATE showed preferential binding to atherosclerotic plaques with plaque-to-wall ratio of 1.7?±?0.3 and 2.1?±?0.5, respectively. However, the aortic uptake and aorta-to-blood ratio of [68Ga]DOTANOC were higher compared to [68Ga]DOTATATE in in vivo PET/CT imaging.

Conclusion

Our results demonstrate superior applicability for [68Ga]DOTANOC and [68Ga]DOTATATE in the detection of atherosclerotic plaques compared to [18F]FDR-NOC.
  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