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   152092篇
  免费   32711篇
  国内免费   2401篇
耳鼻咽喉   5230篇
儿科学   5522篇
妇产科学   2448篇
基础医学   3530篇
口腔科学   1544篇
临床医学   26888篇
内科学   47731篇
皮肤病学   7618篇
神经病学   14948篇
特种医学   6451篇
外科学   41345篇
综合类   269篇
现状与发展   72篇
一般理论   7篇
预防医学   7242篇
眼科学   3373篇
药学   1150篇
中国医学   8篇
肿瘤学   11828篇
  2023年   4820篇
  2022年   1172篇
  2021年   3145篇
  2020年   6089篇
  2019年   2262篇
  2018年   7470篇
  2017年   7405篇
  2016年   8503篇
  2015年   8460篇
  2014年   15602篇
  2013年   15790篇
  2012年   5651篇
  2011年   5670篇
  2010年   10433篇
  2009年   14350篇
  2008年   6003篇
  2007年   4183篇
  2006年   6681篇
  2005年   3925篇
  2004年   3167篇
  2003年   2162篇
  2002年   2233篇
  2001年   3833篇
  2000年   3024篇
  1999年   3252篇
  1998年   3677篇
  1997年   3429篇
  1996年   3365篇
  1995年   3237篇
  1994年   1964篇
  1993年   1579篇
  1992年   1379篇
  1991年   1431篇
  1990年   1078篇
  1989年   1194篇
  1988年   1029篇
  1987年   849篇
  1986年   911篇
  1985年   730篇
  1984年   564篇
  1983年   542篇
  1982年   523篇
  1981年   412篇
  1980年   371篇
  1979年   321篇
  1978年   339篇
  1977年   408篇
  1975年   286篇
  1972年   293篇
  1970年   268篇
排序方式: 共有10000条查询结果,搜索用时 629 毫秒
991.
Palmar advancement flap with V-Y closure for thumb tip injuries   总被引:1,自引:0,他引:1  
The palmar advancement flap with V-Y closure was used in two patients with thumb tip injuries. This technique allows more distal advancement of the flap than does a conventional palmar advancement flap and does not require skin graft coverage.  相似文献   
992.
We examined records of sedations provided by the paediatric anaesthesiology staff for 455 children (ages 1 mo-17 yr) undergoing MRI or CT scans at our institution over a twelve-month period with regard to the monitoring of adverse events: excessive sedation, agitation, vomiting, hypoxaemia, and major airway compromise. One hundred-and-thirty-one patients (29%) received chloral hydrate; 324 patients (71%) received propofol. All patients were monitored with continuous noninvasive pulse oximetry and received supplemental oxygen via nasal cannulae. Of the patients who received chloral hydrate, 64 (49%) were over one year of age; of the patients who received propofol, 318 (98%) were one year of age or older. In the chloral hydrate group, 23 patients (19%) were deemed excessively sedated and four patients (3%) were agitated; no patients in the propofol group experienced any of the adverse outcomes reviewed. Furthermore, no patients in either group had significant airway compromise and none was admitted to the hospital as a result of the sedation.  相似文献   
993.
Urban and Rural Differences in Health Insurance and Access to Care   总被引:3,自引:0,他引:3  
This study considers differences in access to health care and insurance characteristics between residents of urban and rural areas. Data were collected from a telephone survey of 10,310 randomly selected households in Minnesota. Sub-samples of 400 group-insured, individually insured, intermittently insured, and uninsured people, were asked about access to health care. Those with group or individual insurance were also asked about the costs and characteristics of their insurance policies.
Rural areas had a higher proportion of uninsured and individually insured respondents than urban areas. Among those who purchased insurance through an employer, rural residents had fewer covered benefits than urban residents (5.1 vs 5.7, P < 0.01) and were more likely to have a deductible (80% versus 40%, P < 0.01). In spite of this, rural uninsured residents were more likely to have a regular source of care than urban residents (69% versus 51%, P < 0.01), and were less likely to have delayed care when they thought it was necessary (21% versus 32%, P<0.01). These differences were confirmed by multivariate analysis.
Rural residents with group insurance have higher out-of-pocket costs and fewer benefits. Uninsured rural residents may have better access to health care than their urban counterparts. Attempts to expand access to health care need to consider how the current structure of employment-based insurance creates inequities for individuals in rural areas as well as the burdens this structure may place on rural providers.  相似文献   
994.
Reversal of diastolic cerebral blood flow in infants without brain death   总被引:1,自引:0,他引:1  
The reversal of diastolic cerebral blood flow has been regarded as a characteristic waveform of brain death and a useful confirming sign. We report 2 patients who had diastolic flow reversal but survived. One, a 1-month-old boy with status epilepticus, had reversal of diastolic cerebral blood flow detected by Doppler ultrasound soon after admission. Reversal disappeared after medical management for increased intracranial pressure and seizure control. He recovered without sequelae. The other, a 6-month-old girl with choroid plexus papilloma, had reversal of diastolic flow during abrupt clinical deterioration. Emergent surgical removal of the tumor was performed and she survived with hemiparesis and psychomotor retardation. Our patients demonstrated that even in the presence of diastolic reversal of cerebral blood flow, prompt and effective treatment can avoid a fatal outcome.  相似文献   
995.
996.
997.
Background: Atelectasis, an important cause of impaired gas exchange during general anesthesia, may be eliminated by a vital capacity maneuver. However, it is not clear whether such a maneuver will have a sustained effect. The aim of this study was to determine the impact of gas composition on reappearance of atelectasis and impairment of gas exchange after a vital capacity maneuver.

Methods: A consecutive sample of 12 adults with healthy lungs who were scheduled for elective surgery were studied. Thirty minutes after induction of anesthesia with fentanyl and propofol, the lungs were hyperinflated manually up to an airway pressure of 40 cmH2 O. FI sub O2 was either kept at 0.4 (group 1, n = 6) or changed to 1.0 (group 2, n = 6) during the recruitment maneuver. Atelectasis was assessed by computed tomography. The amount of dense areas was measured at end-expiration in a transverse plane at the base of the lungs. The ventilation-perfusion distributions (V with dot A/Q with dot) were estimated with the multiple inert gas elimination technique. The static compliance of the total respiratory system (Crs) was measured with the flow interruption technique.

Results: In group 1 (FIO2 = 0.4), the recruitment maneuver virtually eliminated atelectasis for at least 40 min, reduced shunt (V with dot A/Q with dot < 0.005), and increased at the same time the relative perfusion to poorly ventilated lung units (0.005 < V with dot A/Q with dot < 0.1; mean values are given). The arterial oxygen tension (PaO2) increased from 137 mmHg (18.3 kPa) to 163 mmHg (21.7 kPa; before and 40 min after recruitment, respectively; P = 0.028). In contrast to these findings, atelectasis recurred within 5 min after recruitment in group 2 (FIO2 = 1.0). Comparing the values before and 40 min after recruitment, all parameters of V with dot A/Q with dot were unchanged. In both groups, Crs increased from 57.1/55.0 ml *symbol* cmH2 O sup -1 (group 1/group 2) before to 70.1/67.4 ml *symbol* cmH2 O sup -1 after the recruitment maneuver. Crs showed as low decrease thereafter (40 min after recruitment: 61.4/60.0 ml *symbol* cmH2 O sup -1), with no difference between the two groups.  相似文献   

998.
Objective. The objective of this study was to develop an interface to allow special physiologic signals (e.g., in a research setting) to be displayed on the invasive pressure channel of conventional clinical monitors. The interface accepts single-ended high-level signals for display using the pressure channel of patient monitors, which use strain-gauge transducers employing direct current (DC) excitation.Methods. By studying the electronic circuitry common to most clinical invasive pressure measurement systems (Wheatstone bridge, differential input instrumentation amplifier) it was possible to develop an interface to convert high-level single-ended signals into the low-level differential signal needed for input to an invasive pressure channel.Results and Conclusions. The device is useful when it is desired to display signals from special transducers on regular patient monitors. Schematic diagrams and sample results are provided.  相似文献   
999.
1000.
Introduction: Opioid-induced rigidity often makes bag-mask ventilation difficult or impossible during induction of anesthesia. Difficult ventilation may result from chest wall rigidity, upper airway closure, or both. This study further defines the contribution of vocal cord closure to this phenomenon.

Methods: With institutional review board approval, 30 patients undergoing elective cardiac surgery participated in the study. Morphine (0.1 mg/kg) and scopolamine (6 micro gram/kg) given intramuscularly provided sedation along with intravenous midazolam as needed. Lidocaine 10% spray provided topical anesthesia of the oropharynx. A fiberoptic bronchoscope positioned in the airway photographed the glottis before induction of anesthesia. A second photograph was obtained after induction with 3 micro gram/kg sufentanil administered during a period of 2 min. A mechanical ventilator provided 10 ml/kg breaths at 10/min via mask and oral airway with jaw thrust. A side-stream spirometer captured objective pulmonary compliance data. Subjective airway compliance was scored. Pancuronium (0.1 mg/kg) provided muscle relaxation. One minute after the muscle relaxant was given, a third photograph was taken and compliance measurements and scores were repeated. Photographs were scored in a random, blinded manner by one investigator. Wilcoxon signed rank tests compared groups, with Bonferroni correction. Differences were considered significant at P <0.05.

Results: Twenty-eight of 30 patients exhibited decreased pulmonary compliance and closed vocal cords after opioid induction. Two patients with neither objective nor subjective changes in pulmonary compliance had open vocal cords after opioid administration. Both subjective and objective compliances increased from severely compromised values after narcotic-induced anesthesia to normal values (P = 0.000002) after patients received a relaxant. Photo scores document open cords before induction, progressing to closed cords after the opioid (P = 0.00002), and opening again after a relaxant was administered (P = 0.00005).  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