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   10876篇
  免费   607篇
  国内免费   210篇
耳鼻咽喉   160篇
儿科学   418篇
妇产科学   95篇
基础医学   684篇
口腔科学   221篇
临床医学   1280篇
内科学   1495篇
皮肤病学   26篇
神经病学   966篇
特种医学   487篇
外科学   2353篇
综合类   1455篇
预防医学   463篇
眼科学   570篇
药学   630篇
  24篇
中国医学   189篇
肿瘤学   177篇
  2024年   41篇
  2023年   230篇
  2022年   413篇
  2021年   580篇
  2020年   481篇
  2019年   377篇
  2018年   405篇
  2017年   420篇
  2016年   450篇
  2015年   410篇
  2014年   798篇
  2013年   779篇
  2012年   649篇
  2011年   645篇
  2010年   488篇
  2009年   549篇
  2008年   491篇
  2007年   490篇
  2006年   388篇
  2005年   289篇
  2004年   314篇
  2003年   273篇
  2002年   202篇
  2001年   180篇
  2000年   163篇
  1999年   150篇
  1998年   114篇
  1997年   92篇
  1996年   99篇
  1995年   95篇
  1994年   67篇
  1993年   54篇
  1992年   64篇
  1991年   55篇
  1990年   35篇
  1989年   39篇
  1988年   33篇
  1987年   38篇
  1986年   35篇
  1985年   50篇
  1984年   29篇
  1983年   19篇
  1982年   22篇
  1981年   15篇
  1980年   16篇
  1979年   18篇
  1978年   18篇
  1977年   11篇
  1976年   7篇
  1975年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Background:When it comes to preterm newborns, respiratory distress syndrome (RDS) is the most frequent respiratory condition. Despite the fact that it is well acknowledged that preterm delivery plays a significant role, the causes of lung damage are still not completely understood. In newborns with extremely low birth weight and neonatal RDS, nasal continuous positive airway pressure has been suggested as the first respiratory assistance for spontaneous breathing. In the current research, we aim to carry out a meta-analysis to assess the effectiveness and safety of high-flow nasal cannula (HFNC) and non-invasive continuous positive airway pressure (nCPAP) in patients with neonatal respiratory distress syndrome (NRDS).Methods:We intend to search the following databases: PubMed, EMBASE, Cochrane Library, Wanfang database, China National Knowledge Infrastructure (CNKI), and Google Scholar, starting from their initial publication until February 2022, to identify randomized controlled trials comparing HFNC to nCPAP in patients with NRDS. The suitable papers will be chosen by 2 writers who will work independently of one another. Using the Cochrane updated technique for risk of bias, each included article will be subjected to an independent data extraction process by the 2 writers who will then independently evaluate the risk of bias. Consequently, a third author will be asked to address any discrepancies that may arise between the writers. It will be necessary to pool the data and do a meta-analysis with the help of the RevMan 5.3 software.Results:In this study, the effectiveness and safety of HFNC will be compared with those of nCPAP in patients with NRDS.Conclusion:If the results of this research are confirmed, they may serve as a summary of the most recent data for non-invasive respiratory assistance in NRDS.Ethics and dissemination:The study will require ethical approval.Registration number:DOI 10.17605/OSF.IO/BKSQ5  相似文献   
52.
构建医药电商平台持续使用意愿理论模型,采用问卷调查分析用户对医药电商平台持续使用意愿及影响因素,结果表明感知有用性和用户主观规范正向影响用户对平台持续使用意愿,感知风险负向影响持续使用意愿.在此基础上提出平台运营建议,包括设计创新、口碑化宣传、建设生态链等.  相似文献   
53.
Background:There is an increasing use of continuous glucose monitoring (CGM) by people with diabetes. Measurement performance is often characterized by the mean absolute relative difference (MARD). However, MARD is influenced by a number of factors and little is known about whether MARD is stable throughout the day.Material and Methods:A total of 24 participants with type 1 diabetes were enrolled in the study. The study was performed for seven in-patient days. Participants wore two CGM systems in parallel and performed additional frequent blood glucose (BG) measurements. On two days, glucose excursions were induced.MARD was calculated between pairs of CGM and BG values, with BG values serving as reference values. ARD values calculated from CGM-BG pairs were grouped by hour of the day. Results were analyzed separately for glucose excursion days and for regular days.Results:Total MARDs for the complete study duration were 12.5% ± 3.6% and 13.2% ± 2.4% (n = 24). Throughout the day marked variability of MARD was observed (8.0% ± 1.3%-16.3% ± 2.9% (G5); 9.1% ± 1.4%-16.3% ± 5.3% (FL), up to n = 157 each). Low(est) MARD values were observed before breakfast and dinner, when subjects were in or near a fasting state. Especially after breakfast and lunch, MARD values were higher than average.Conclusions:Analytical performance of the two CGM systems, assessed by MARD, was found to vary markedly throughout the day. Activities of daily life likely triggered these variations. An increasing number of CGM users base therapeutic decisions on CGM values, and they should be aware of these variations of performance throughout the day.  相似文献   
54.
55.
液相连续反应釜反应效果可如下进行预测。通过实验室装置测定并绘制拟定条件下的反应动力学曲线。把生产釜模拟为带死角和短路的理想釜,用水作介质在生产釜中进行流动模型试验,测量一系列停留时间分布密度函数,得到两个模型参数,并建立操作线方程。反应动力学曲线和操作线的交点为此液相连续反应釜的预测结果。  相似文献   
56.
目的:探讨持续被动运动活动器(CPM)在下肢手术后功能锻炼的效果。方法:将50例下肢骨折术后患者随机分为对照组和实验组,各25例。对照组术后行常规护理,实验组术后早期实施康复训练,术后2个月比较两组患者的康复效果。结果:实验组有效率明显高于对照组,差异有统计学意义(P<0.05)。结论:应用CPM有效防止了下肢手术后膝关节僵直和肌肉挛缩,可促进患者早日康复。  相似文献   
57.
With the recent development of reliable portable pumps and safe venous access systems, continuous infusion of chemotherapeutic agents on an out-patient basis has become feasible. Advantages of continuous infusion are the long-term exposure of tumour cells to the drug and the fact that most toxic effects are reduced for doxorubicin, epirubicin and mitoxantrone due to elimination of the high peak plasma levels. Preliminary data for doxorubicin suggest that its antitumour activity is maintained. Pharmacokinetic studies with epirubicin and mitoxantrone showed a linear relationship between drug dose infused and the steady-state plasma level for these drugs. The area under the curve for leukocytes drug level was higher during continuous infusion than after an equitoxic bolus injection of epirubicin and mitoxantrone. Well-randomized clinical trials will be necessary to investigate the role of continuous infusion of antracyclines and mitoxantrone in cancer chemotherapy in the future.  相似文献   
58.
Fetal stroke is an important cause of cerebral palsy but is difficult to diagnose unless imaging is undertaken in pregnancies at risk because of known maternal or fetal disorders. Fetal ultrasound or magnetic resonance imaging may show haemorrhage or ischaemic lesions including multicystic encephalomalacia and focal porencephaly. Serial imaging has shown the development of malformations including schizencephaly and polymicrogyra after ischaemic and haemorrhagic stroke. Recognised causes of haemorrhagic fetal stroke include alloimmune and autoimmune thrombocytopaenia, maternal and fetal clotting disorders and trauma but these are relatively rare. It is likely that a significant proportion of periventricular and intraventricular haemorrhages are of venous origin. Recent evidence highlights the importance of arterial endothelial dysfunction, rather than thrombocytopaenia, in the intraparenchymal haemorrhage of alloimmune thrombocytopaenia. In the context of placental anastomoses, monochorionic diamniotic twins are at risk of twin twin transfusion syndrome (TTTS), or partial forms including Twin Oligohydramnios Polyhydramnios Sequence (TOPS), differences in estimated weight (selective Intrauterine growth Retardation; sIUGR), or in fetal haemoglobin (Twin Anaemia Polycythaemia Sequence; TAPS). There is a very wide range of ischaemic and haemorrhagic injury in a focal as well as a global distribution. Acute twin twin transfusion may account for intraventricular haemorrhage in recipients and periventricular leukomalacia in donors but there are additional risk factors for focal embolism and cerebrovascular disease. The recipient has circulatory overload, with effects on systemic and pulmonary circulations which probably lead to systemic and pulmonary hypertension and even right ventricular outflow tract obstruction as well as the polycythaemia which is a risk factor for thrombosis and vasculopathy. The donor is hypovolaemic and has a reticulocytosis in response to the anaemia while maternal hypertension and diabetes may influence stroke risk. Understanding of the mechanisms, including the role of vasculopathy, in well studied conditions such as alloimmune thrombocytopaenia and monochorionic diamniotic twinning may lead to reduction of the burden of antenatally sustained cerebral palsy.  相似文献   
59.
跟骨骨折后距下后关节面应力改变的实验研究   总被引:2,自引:0,他引:2  
目的研究载荷条件下跟骨后关节面骨折后,所受应力的改变对距下关节的影响,为临床治疗提供理论依据。方法取6具包括完整足和胫腓骨远端15~20cm的新鲜标本。剔除皮肤、肌肉和跟腱,保留除外距下关节后方的关节囊部分,保持韧带和关节囊的完整。将压敏片插入距下关节的后关节间隙,中立位状态下分别在500N载荷下,对6具标本的距下关节进行加载,完成完整足的测试。然后模拟原始骨折线用微型摆动锯将跟骨后关节面分为前内和后外2块,接着按解剖复位、后外侧骨折块向跖侧移位2、5、10mm等条件重复上述实验,记录距下后关节面所受应力的改变。结果完整的距下后关节面承载的平均应力为(1.83±0.56)MPa。跟骨后外侧骨折块向跖侧移位2mm时,后关节面所承载的应力为(2.41±0.84)MPa,较完整跟骨承载应力显著增加(P<0.01)。结论跟骨距下关节后关节面骨折跖侧移位≥2mm即应手术复位。  相似文献   
60.
目的:对照研究连续硬膜外麻醉(CEA)和全身麻醉下人工全膝关节置换术(TKA)后深静脉血栓(DVT)的发生率,并探析其各自的临床意义。方法:分析2013年4月~2015年5月在我院接受治疗的68例患者的临床资料。将入选者随机分成 CEA 组和全麻组两组,各34例。比较两组患者的一般资料、术前术后的相关指标以及术前凝血、血小板相关指标以及 DVT 的发生率。结果:两组患者的一般资料无统计学差异。两组患者术中、术后的相关指标间差异均不明显。两组患者术前凝血与血小板比较无统计学差异。DVT 的总发生率为19.1%(13/68),其中单纯远端血栓有12例,近端血栓有1例,无肺栓塞及髂静脉血栓患者。CEA 组的 DVT 发生率明显低于全麻组。结论:CEA 可以显著降低 TKA 后 DVT 的发生率,疗效显著。  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