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   1624篇
  免费   94篇
  国内免费   6篇
耳鼻咽喉   15篇
儿科学   67篇
妇产科学   38篇
基础医学   168篇
口腔科学   19篇
临床医学   207篇
内科学   451篇
皮肤病学   13篇
神经病学   84篇
特种医学   56篇
外科学   281篇
综合类   19篇
预防医学   112篇
眼科学   18篇
药学   108篇
中国医学   6篇
肿瘤学   62篇
  2023年   10篇
  2022年   15篇
  2021年   28篇
  2020年   13篇
  2019年   27篇
  2018年   25篇
  2017年   19篇
  2016年   29篇
  2015年   36篇
  2014年   46篇
  2013年   46篇
  2012年   88篇
  2011年   101篇
  2010年   55篇
  2009年   44篇
  2008年   97篇
  2007年   93篇
  2006年   108篇
  2005年   87篇
  2004年   87篇
  2003年   74篇
  2002年   79篇
  2001年   45篇
  2000年   56篇
  1999年   39篇
  1998年   13篇
  1997年   11篇
  1996年   9篇
  1995年   12篇
  1994年   7篇
  1993年   7篇
  1992年   35篇
  1991年   21篇
  1990年   26篇
  1989年   29篇
  1988年   24篇
  1987年   18篇
  1986年   18篇
  1985年   12篇
  1984年   15篇
  1983年   11篇
  1982年   11篇
  1979年   7篇
  1977年   7篇
  1976年   7篇
  1974年   6篇
  1973年   12篇
  1969年   6篇
  1968年   5篇
  1967年   5篇
排序方式: 共有1724条查询结果,搜索用时 15 毫秒
71.
One of the disabilities in patients with cerebral palsy (CP) is dysphagia. To establish the prevalence of dysphagia in a population of children with CP, and to determine if any factors are related to dysphagia, we studied 56 CP patients, 5-21 years, enrolled in a primary school for the disabled. Fifteen patients (27%) had either radiographic or clinical evidence of dysphagia. These 15 patients were compared to the remaining 41 patients without dysphagia. Using data obtained from chart review and interviews with speech pathologists, several factors that contributed to dysphagia were found. These included: bite reflexes, slowness of oral intake, poor trunk control, inability to feed independently, anticonvulsant medication, coughing with meals, choking, and pneumonia. We also noted trends in the following factors: presence of tongue thrusting, presence of drooling, severity of CP, poor head control, severity of mental retardation, seizures, and speech disorders. Factors not related to the presence of dysphagia include: subject age, cause of CP, and type of CP. Early, aggressive work-up and identification in CP patients with the risk factors outlined above can reduce the associated pulmonary complications.  相似文献   
72.
Two neonates undergoing arterial switch procedure developed life-threatening pulmonary hypertension intraoperatively. In one patient, bradycardia, hypotension, and electrocardiographic (ECG) evidence of myocardial ischemia suddenly occurred 20 minutes after uneventful weaning from cardiopulmonary bypass. Lifting a palpably hypertensive main pulmonary artery (MPA) resulted in reproducible hemodynamic improvement. Because the patient was already on full ventilatory support and a nitroglycerin infusion, the MPA was suspended onto the anterior chest wall. In the other patient, after removal of intraoperative drapes, severe generalized swelling and cyanosis were noted. The central venous pressure had risen to 25 mmHg, and the PO2 had dropped to 52 mmHg on 100% FIO2. The systolic arterial pressure and ECG remained normal. Immediate reexploration revealed a palpably hypertensive MPA. The coronary arteries implanted more laterally on the neoaorta were uncompromised. Amrinone loading and infusion produced immediate improvement. We believe that surgeons should be aware that pulmonary hypertension can cause coronary artery compression and right heart failure in neonates undergoing the arterial switch procedure. Lateral placement of the coronary artery and aggressive use of pulmonary vasodilators can minimize the problem.  相似文献   
73.
Intra-aortic balloon pumps (IABPs) cannot sustain hemodynamics if the left heart is severely injured. An enhanced IABP was evaluated in 6 anesthetized dogs with acute stenosis of the left anterior descending coronary artery, regional left ventricular (LV) stunning, and global LV dysfunction. An IABP balloon was inserted into the descending aorta and an external chamber containing another IABP balloon was connected to the aorta through a catheter inserted into the left subclavian artery. This emulated the enhanced IABP with a conduit from its external chamber passing axially through an internal IABP balloon. Compared to IABP, enhanced IABP improved hemodynamics and LV function in all conditions. During severe LV dysfunction and circulatory failure, IABP failed to augment diastolic aortic pressure or improve coronary and carotid flows. Enhanced IABP augmented diastolic pressure from 32 +/- 3 mm Hg to 87 +/- 2 mm Hg and increased coronary and carotid flows. Enhanced IABP may be a lifesaving device for patients with severe LV failure.  相似文献   
74.
Patients who undergo intrathoracic operative procedures for malignancy may require sacrifice of a recurrent laryngeal nerve. Postoperative vocal fold paralysis may lead to diminished cough with secretion retention, aspiration, and life-endangering pneumonia. This study retrospectively reviews our institution's experience of 23 patients who underwent type I thyroplasty within the 2-week (acute) period after thoracic surgery. Primary lung cancer (n = 16) was the most common disease. Upper lobectomy (n = 9) and pneumonectomy (n = 7) were the most frequent surgical procedures. Silicone medialization alone (n = 11) or with arytenoid adduction (n = 12) was performed. There were no significant postoperative complications. Improvements in hoarseness (86%), dyspnea (72%), dysphagia (50%), and aspiration (79%) were noted. Pulmonary status improved after vocal fold medialization, as reflected by decreased need for therapeutic bronchoscopy in the majority of patients in the postoperative period. Type I thyroplasty for vocal fold paralysis in the acute phase following thoracic surgery is well tolerated and is associated with improved patient outcome with no postoperative deaths in this high-risk patient population.  相似文献   
75.
BACKGROUND: The histologic criteria defining bronchioloalveolar carcinoma (BAC) were recently revised, but it is unclear whether these criteria predict clinical behavior. This study determined the outcome of resected BAC in relationship to clinical and radiologic disease pattern, and pathologic features. METHODS: Between 1989 and 2000, 100 consecutive surgically treated patients with adenocarcinomas exhibiting various degrees of BAC features were retrospectively studied. Histology was reviewed; tumors were classified as pure BAC, BAC with focal invasion, and adenocarcinoma with BAC features. Clinical and radiologic pattern were classified as unifocal, multifocal, or pneumonic. Demographic data, tumor stage, and outcome were recorded. Survival was analyzed by the Kaplan-Meier method, and prognostic factors were determined by the log-rank test. RESULTS: Patient median age was 65, and 74% of the patients were female. Pure BAC, BAC with focal invasion, and adenocarcinoma with BAC features occurred in 47, 21, and 32 patients, respectively. Unifocal disease occurred in 64 patients, multifocal in 29, and pneumonic in 7. Seventy-one patients had stage I/II tumors, 22 had stage III/IV, and 7 patients had Stage X tumors. Overall 5-year survival was 74%. There was no significant difference in survival among the three histologic subtypes. The pneumonic pattern had significantly worse survival compared with unifocal and multifocal patterns. Pathologic stage predicted survival, with 5-year survivals for I/II and III/IV of 83.7% and 59.6%, respectively. CONCLUSIONS: Clinical pattern and pathologic stage, but not the degree of invasion on histologic examination predict survival. Multifocal disease is associated with excellent long-term survival after resection. The favorable survival of stage III/IV BAC indicates that the current staging system does not fully describe this disease in patients undergoing resection because of its distinct tumor behavior.  相似文献   
76.
77.
The need to manage medical information in healthcare delivery requires that information technology be optimized in diagnosing disease; in planning and administering treatment; and in monitoring patient outcomes, services, and costs. The goals of this article are twofold: (1) to identify healthcare-specific software that addresses specific parameters set forth by the World Health Organization (WHO) for healthcare information systems and (2) to identify issues that managers should keep in mind when choosing an integrated information systems software package. For our analysis, we gathered, through Internet research, information about more than 400 software products from more than 200 companies.  相似文献   
78.
OBJECT: The benefits of measuring cerebral oxygenation in patients with brain injury are well accepted; however, jugular bulb oximetry, which is currently the most popular monitoring technique used has several shortcomings. The goal of this study was to validate the use of a new multiparameter sensor that measures brain tissue oxygenation and metabolism (Neurotrend) by comparing it with positron emission tomography (PET) scanning. METHODS: A Neurotrend sensor was inserted into the frontal region of the brain in 19 patients admitted to the neurointensive care unit. After a period of stabilization, the patients were transferred to the PET scanner suite where C15O, 15O2, and H2(15)O PET scans were obtained to facilitate calculation of regional cerebral blood volume, O2 metabolism, blood flow, and O2 extraction fraction (OEF). Patients were given hyperventilation therapy to decrease arterial CO2 by approximately 1 kPa (7.5 mm Hg) and the same sequence of PET scans was repeated. For each scanning sequence, end-capillary O2 tension (PvO2) was calculated from the OEF and compared with the reading of brain tissue O2 pressure (PbO2) provided by the sensor. In three patients the sensor was inserted into areas of contusion and these patients were eliminated from the analysis. In the subset of 16 patients in whom the sensor was placed in healthy brain, no correlation was found between the absolute values of PbO2 and PvO2 (r = 0.2, p = 0.29); however a significant correlation was obtained between the change in PbO2 (deltaPbO2) and the change in PvO2 (deltaPvO2) produced by hyperventilation in a 20-mm region of interest around the sensor (p = 0.78, p = 0.0035). CONCLUSIONS: The lack of correlation between the absolute values of PbO2 and PvO2 indicates that PbO2 cannot be used as a substitute for PvO2. Nevertheless, the positive correlation between deltaPbO2 and deltaPvO2 when the sensor had been inserted into healthy brain suggests that tissue PO2 monitoring may provide a useful tool to assess the effect of therapeutic interventions in brain injury.  相似文献   
79.
The 'biphasic transmittance waveform' (BTW) refers to a decrease in light transmittance that often occurs prior to clotting in coagulation assays of critically ill patient plasmas. It correlates with disseminated intravascular coagulation and mortality. The present work shows that the BTW is due to the rapid formation of a precipitate and a coincident change in turbidity in re-calcified plasma. The precipitate was isolated from patient plasma and contained lipids typical of very low density lipoprotein (VLDL), plus the proteins apolipoprotein B-100 and C-reactive protein (CRP). Precipitation also occurred in normal plasma supplemented with CRP. In addition, CRP precipitated with VLDL and intermediate density lipoprotein, but not low density lipoprotein or high density lipoprotein. The Kd value for the CRP/VLDL interaction is 340 nM. The IC50 value of Ca2+ for complex formation is 5.0 mM, and epsilon-aminocaproic acid inhibits the process. In 15 plasmas with the BTW from critically ill patients, CRP was highly elevated (77-398 microg/mL) and VLDL cholesterol ranged from 0.082 to 1.32 mM. The magnitude of the turbidity change on re-calcification correlated well with the calculated level of the CRP/VLDL complex. Thus, the Ca2+-dependent formation of a complex between CRP and VLDL accounts for the BTW.  相似文献   
80.
Gender is a health determinant, but gender itself is influenced, in part, by biological and psychological variables. Understanding gender's influence on health therefore requires an understanding of the determinants of the construct gender. A review of certain gender determinants is presented. The authors consider the modifiability of these determinants and present recommendations about which of these determinants should be targeted for health promotion and policy creation activities. In concluding, they argue that gender is a multidetermined construct that encompasses many factors that may be modifiable through intervention, and consideration of all of these factors should be vigorously pursued.  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