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   5099篇
  免费   316篇
  国内免费   74篇
耳鼻咽喉   50篇
儿科学   38篇
妇产科学   39篇
基础医学   96篇
口腔科学   38篇
临床医学   980篇
内科学   344篇
皮肤病学   22篇
神经病学   84篇
特种医学   50篇
外科学   1114篇
综合类   1009篇
预防医学   448篇
眼科学   19篇
药学   864篇
  8篇
中国医学   115篇
肿瘤学   171篇
  2024年   32篇
  2023年   113篇
  2022年   243篇
  2021年   236篇
  2020年   261篇
  2019年   214篇
  2018年   199篇
  2017年   171篇
  2016年   159篇
  2015年   229篇
  2014年   462篇
  2013年   435篇
  2012年   494篇
  2011年   509篇
  2010年   376篇
  2009年   294篇
  2008年   191篇
  2007年   172篇
  2006年   142篇
  2005年   128篇
  2004年   78篇
  2003年   58篇
  2002年   54篇
  2001年   38篇
  2000年   30篇
  1999年   33篇
  1998年   30篇
  1997年   19篇
  1996年   10篇
  1995年   14篇
  1994年   14篇
  1993年   4篇
  1992年   6篇
  1991年   3篇
  1990年   5篇
  1989年   4篇
  1987年   6篇
  1986年   3篇
  1985年   2篇
  1984年   2篇
  1982年   2篇
  1981年   2篇
  1978年   1篇
  1976年   2篇
  1975年   1篇
  1974年   2篇
  1972年   1篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
排序方式: 共有5489条查询结果,搜索用时 156 毫秒
21.
Many studies have shown that health conditions experienced in childhood play an important role on an individual's adult mortality. Recent research suggests that past reductions in early life exposure to infectious diseases have been a major contributor to the historical decline in old-age mortality. Drawing on French-Canadian data from cohorts born in the 17th and 18th centuries, we test whether a progressive deterioration in early life conditions (as revealed by an increasing infant mortality rate) translates into a decrease in survival prospects in late life. We use traditional demographic measures such as the age-specific probability of death, and a series of proportional hazard models to control for familial and environmental conditions. Results point toward little evidence of any early life effects. The trend of increasing infant mortality does not correlate with a general increase of mortality in older ages within the same cohorts. Period changes affecting survival at older ages (war, epidemics) as well as demographic and biological characteristics shared within families have a much larger role in old-age mortality than early life characteristics shared within the same cohorts.  相似文献   
22.
目的 对重组人脑钠素(rhBNP)用于心脏手术围术期处理的可行性、安全性和有效性进行初步观察,并与硝普钠的作用进行比较。方法 选择择期心脏手术病人22例,随机分为rhBNP组(B组)和硝普钠(SNP)组(s组),每组11例。比较rhBNP与SNP对病人血流动力学和肝肾功能的影响。结果 与给药前和S组比较,B组用药后15、30、60、120和180min各点心输出量增加显著(P〈0.05,P〈0.01);B组与给药前比较,给药后即刻、15、30和60min时点外周血管阻力下降显著(P〈0.05);给药后即刻、15和30点与S组比较,下降显著(P〈0.05)。B组肺毛细血管楔压(PCWP)与用药前比较,用药后即刻、15、30、60、120和180min下降显著(P〈0.05,P〈0.01);与S组比较,给药后30、60、120和180min差异有统计学意义(P〈0.05,P〈0.01)。S组PCWP与用药前比较,用药后60min、120min和180min下降显著(P〈0.05)。B组与输注rhBNP前以及S组比较,平均动脉压、心率和中心静脉压差异均无统计学意义。输注rhBNP后病人24h尿量明显增加。用药过程中以及30d后进行电话随访,未见药物不良反应。结论 rhBNP用于心脏手术围术期处理是可行的,具有改善心功能和稳定循环的作用。  相似文献   
23.
目的探讨老年人股骨颈骨折的治疗及围手术期的处理。方法回顾性分析2003年1月~2006年12月手术治疗的201例老年股骨颈骨折患者资料,其中男51例,女150例,年龄60~98岁,平均78.2岁。按Garden分型,Ⅱ型20例,Ⅲ型86例,Ⅳ型95例。采用多枚中空螺钉固定、Morre型人工股骨头置换术或双极人工股骨头置换手术进行治疗。结果本组患者平均住院10~14d,5~7d即能早期下床活动,住院期间及术后1年内无一例死亡。85%患者获得8个月~4年(平均2年)的随访,功能恢复按Harris评分,优良率为85%。结论老年人各脏器机能衰退,多同时合并各种内科疾病,手术治疗存在风险,但老年人股骨颈骨折的手术治疗仍能取得满意疗效。  相似文献   
24.
目的为了观察甲状腺功能亢进症(甲亢)手术的围手术期的护理与疗效。方法全部患者均采用深入细致的心理护理、术前准备和术前术后病情密切观察以及对术后并发症的防治等方法。结果全组手术治疗168例,治愈163例(97.0%),术后并发甲低3例(1.8%),2例(1.2%)死于术后呼吸道误吸窒息及急性左心衰。结论强高甲亢手术围手术期的护理是保证手术安全、减少病死率及术后并发症的重要环节。  相似文献   
25.
OBJECTIVES: to summarize existing evidence regarding the benefits and the risks of all available interventional and medical means aimed at cardiac risk reduction in patients undergoing vascular surgery. DESIGN: review of the literature. MATERIALS AND METHODS: a critical review of all studies examining the impact of various prophylactic cardiac maneuvers on perioperative outcome following vascular surgery was performed. Overall mortality, cardiac mortality and myocardial infarction rate were used as the outcome measures. RESULTS: coronary artery bypass grafting is associated with a 60% decrease in perioperative mortality in patients undergoing vascular surgery, but in most of the cases this decrease does not outweigh the combined risk of the cardiac and the subsequent noncardiac vascular procedure. Data supporting the cardioprotective effect of percutaneous transluminal angioplasty in the perioperative setting are insufficient. beta-blockade has been shown to decrease perioperative mortality and cardiac morbidity in both high-risk (strong evidence) and low-risk (weak evidence) patients. CONCLUSIONS: coronary revascularization is rarely indicated to simply get the patient through vascular surgery and should be reserved for patients who would need it irrespective of the scheduled vascular procedure. Among all available pharmacological agents, including beta-blockers, alpha-agonists, calcium channel blockers and nitrates, only beta-blockers have been proven to reduce the cardiac risk of vascular surgery.  相似文献   
26.
Patients with a particular thrombotic profile may be at greaterrisk of myocardial infarction during coronary artery bypassgraft surgery. The thrombotic profile of 50 patients admitted to hospital withstable angina pectoris was determined prior to haemodynamicinvestigation. ECG results and determination of cardiac enzymesshowed that 12 patients had suffered a perioperative myocardialinfarction. These patients had a higher mean atheroscleroticscore (42.1 ± 10.5 vs 32.9 ± 13, P<0.02), alonger aortic cross clamp time (59 ± 15.2 vs 45.7 ±16.3 min, P < 0.05), lower serum levels of protein C (101.2±26vs 124.7+ 31.4%, P<0.05) and tissue plasminogen activator(322 ± 580 vs 2307±2830 IU ml–1, P<0.01). There were no differences between the two groups in Jenkin'scoronary score, the number and type of grafts, ejection fraction,left ventricular end-diastolic pressure, lipid profile or levelsof markers of platelet release. In addition to a more severe distal coronary atheroma and alonger aortic cross-clamp time, patients with impaired endothelialfibrinolytic activity appeared to be at greater risk of myocardialinfarction during coronary artery bypass graft surgery.  相似文献   
27.
The mammalian Per1 gene is an important component of the core cellular clock mechanism responsible for circadian rhythms. The rodent liver and other tissues rhythmically express Per1 in vitro but typically damp out within a few cycles. In the liver, the peak of this rhythm occurs in the late subjective night in an ad lib-fed rat, but will show a large phase advance in response to restricted availability of food during the day. The relationship between this shift in the liver clock and food-anticipatory activity (FAA), the circadian behavior entrained by daily feeding, is currently unknown. Insulin is released during feeding in mammals and could serve as an entraining signal to the liver. To test the role of insulin in the shift in liver Per1 expression and the generation of FAA, per-luciferase transgenic rats were made diabetic with a single injection of streptozotocine. Following 1 week of restricted feeding and locomotor activity monitoring, liver was collected for per-luc recording. In two separate experiments, FAA emerged and liver Per1 phase-shifted in response to daytime 8-h food restriction. The results rule out insulin as a necessary component of this system.  相似文献   
28.
Zusammenfassung Eine perioperative antibiotische Kurzprophylaxe mit 2 g Cefamandol intravenös bei Narkoseeinleitung wurde bei 12 Patienten während coronarchirurgischer Eingriffe unter Verwendung der Herz-Lungen-Maschine durchgeführt. Bei Beginn der extrakorporalen Zirkulation (= EKZ) kam es infolge Hämodilution zu einem Absinken der Serumkonzentrationen von 110,96 ± 40,29 mcg/ml auf 70,89 ± 34,65 g/ml innerhalb von 10 min. Im weiteren Verlauf der EKZ war der Abfall der Serumspiegel gleich schnell wie davor und danach. Nach 240 min fanden sich noch Serumspiegel von 16,80 ± 9,32 g/ml. Als Ursache für das Versagen einer antibiotischen Prophylaxe kommt bei einer Operationsdauer von mehr als 4 h das Absinken der Serumspiegel unter die minimale Hemmkonzentration der entsprechenden Keime in Frage.
Perioperative cefamandole prophylaxis in aortocoronary bypass operations: Course of serum concentration during extracorporeal circulation
Summary Antibiotic prophylaxis with 2 g Cefamandole at induction of anaesthesia was performed in 12 male patients undergoing aortocoronary bypass surgery. Caused by hemodilution, there was a marked decrease of serum concentration at the beginning of extracorporeal circulation, from 110.96 ± 40.29 mcg/ml to 70.89 ± 34.65 mcg/ml within 10 min. During extracorporeal circulation, elimination was as fast as before and after perfusion. 240 min after application, mean serum concentrations of 16.80 ± 9.32 mcg/ml were measured. Failure of antibiotic prophylaxis in operations exceeding 4 h might be due to unadaequate antibiotic concentrations, beyond the minimal inhibitory concentration for the pathogens, reported to cause infections after cardiac operations.
  相似文献   
29.
目的构建老年髋部骨折患者围术期营养管理模式,促进患者早手术、早下地、早康复。方法针对老年髋部骨折患者营养管理现状,采用课题研究型品管圈活动进行改进。经过科学循证、专家指导等,从术前、术后及家庭三个环节,骨科、营养科、家庭三个维度,人员、制度、材料设备、方法、信息五个方面,制定三大对策群组并予以实施,包括组建营养支持团队、构建营养管理策略、搭建多维信息交互平台等。结果老年髋部骨折患者首次下地时间缩短为26.7 h,平均住院日缩短为5.6 d,实现了早手术、早下地、早康复的目标。结论对老年髋部骨折患者实施个性化、全流程的序贯性营养干预具有重要意义。后续还需开展大样本多中心研究以进一步验证成效,数据自动采集与智能反馈也是今后研究重点。  相似文献   
30.
As the population ages, more older adults will undergo surgical procedures, and common physiologic changes can raise the risk for surgical complications while increasing morbidity and mortality. In conjunction with the National Surgical Quality Improvement Program, we piloted a comprehensive and interdisciplinary assessment and intervention protocol for perioperative care for patients aged ≥75 years undergoing elective general, gynecology-oncologic, and orthopedic surgery. The intervention included screening tools for cognitive, functional, and nutritional deficits, a Geriatric Nurse Champion on each inpatient surgical unit, and an interdisciplinary Geriatric Surgery Quality Committee. Our intervention group was compared to surgical patients during the same time period 1 year prior to the intervention, and the groups were well matched in demographics and comorbidities. The intervention group had significantly higher rates of advance care plan documentation in analysis of all patients (P < .001) and in subgroup analysis of those 85 and older (P = .006). The preintervention group had less postoperative delirium compared to the postintervention group but it was not significant and there was no difference in length of stay between groups. Various explanations for the minimal impact of the protocol exist: small sample size, presence of other hospital initiatives to reduce pressure ulcer and delirium, and clinician’s awareness of project planning that led to incorporating ideas prior to official implementation. Future research implementing this protocol in naïve and/or underperforming institutions may demonstrate a greater effect. Larger sample size as well as implementation in other surgical fields may reveal a significant impact. However, if additional study does not reveal a meaningful impact of a comprehensive geriatric assessment for surgical patients, then consideration must be made regarding unrecognized factors in surgical care for older adults or perhaps that factors cannot be mitigated in older adults because they are intrinsically a higher surgical risk.  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