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   25042篇
  免费   1764篇
  国内免费   604篇
耳鼻咽喉   124篇
儿科学   753篇
妇产科学   296篇
基础医学   1192篇
口腔科学   179篇
临床医学   5132篇
内科学   4866篇
皮肤病学   157篇
神经病学   2254篇
特种医学   1505篇
外国民族医学   1篇
外科学   4128篇
综合类   3190篇
现状与发展   4篇
预防医学   811篇
眼科学   221篇
药学   1430篇
  19篇
中国医学   504篇
肿瘤学   644篇
  2024年   59篇
  2023年   545篇
  2022年   905篇
  2021年   1198篇
  2020年   1177篇
  2019年   992篇
  2018年   954篇
  2017年   943篇
  2016年   886篇
  2015年   920篇
  2014年   1778篇
  2013年   1777篇
  2012年   1417篇
  2011年   1519篇
  2010年   1250篇
  2009年   1185篇
  2008年   1158篇
  2007年   1083篇
  2006年   1004篇
  2005年   899篇
  2004年   680篇
  2003年   648篇
  2002年   533篇
  2001年   458篇
  2000年   371篇
  1999年   293篇
  1998年   297篇
  1997年   299篇
  1996年   232篇
  1995年   242篇
  1994年   197篇
  1993年   157篇
  1992年   168篇
  1991年   133篇
  1990年   119篇
  1989年   113篇
  1988年   113篇
  1987年   71篇
  1986年   90篇
  1985年   109篇
  1984年   92篇
  1983年   50篇
  1982年   65篇
  1981年   52篇
  1980年   39篇
  1979年   39篇
  1978年   22篇
  1977年   22篇
  1976年   22篇
  1975年   9篇
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
21.
22.
The Impella 5.0, a percutaneously inserted left ventricular assist device, has been used to support patients who have severe heart failure or who are undergoing high-risk percutaneous coronary intervention. We report our surgical placement of the Impella 5.0, through a graft sewn to the aorta, to unload the left ventricle of a 59-year-old man who was undergoing venoarterial extracorporeal membrane oxygenation for postcardiotomy shock. The patient underwent successful placement of a long-term left ventricular assist device before his discharge from the hospital. The versatility of the Impella 5.0 is exemplified in this patient who was successfully bridged to long-term support.  相似文献   
23.
静脉血栓栓塞症(VTE)是指各种病因(如静脉血滞缓、静脉壁血管内膜损伤或血液高凝等)导致血液在静脉系统不正常凝集的一组疾病,包括肺动脉栓塞(PE)和深静脉血栓形成(DVT)。上海市普通外科临床质量控制中心自2018年发布《上海市普通外科住院病人静脉血栓栓塞症防治管理规范》(以下简称2018版《规范》)至今已2年,推动了上海市普通外科围手术期血栓防治工作的推广,同时积累了上海在血栓防治方面的临床数据。截止至2019年9月,上海市二级以上医院已有88%建立VTE防控体系,在病史中包含了VTE风险评估表,并且大部分医院已有电子病案的嵌入或纸质病史的记录;84%的医院有VTE和PE的联合会诊团队;92%医院的普通外科已按照2018版《规范》为住院病人评估VTE风险,74%的科室在病人手术后再次评估VTE风险,38%的科室在出院前会再次为病人评估VTE风险。上海市普通外科在临床实践中防治VTE的理念和实践有了很大进步,但与先进国家和医院的防治实践相比仍有较大差距。  相似文献   
24.
Pelvic venous disorders (PeVDs) in women can present with chronic pelvic pain, lower-extremity and vulvar varicosities, lower-extremity swelling and pain, and left-flank pain and hematuria. Multiple evidence gaps exist related to PeVDs with the consequence that nonvascular specialists rarely consider the diagnosis. Recognizing this, the Society of Interventional Radiology Foundation funded a Research Consensus Panel to prioritize a research agenda to address these gaps. This paper presents the proceedings and recommendations from that Panel.  相似文献   
25.
《Clinical neurophysiology》2019,130(9):1562-1569
ObjectiveConventional deep brain stimulation (DBS) systems with ring-shaped leads generate spherical electrical fields. In contrast, novel directional leads use segmented electrodes. Aim of this study was to quantify the impedance variations over time in subjects with the directional Cartesia-Boston® system.MethodsImpedance records, programming settings, and clinical data of 11 consecutive Parkinsonian patients implanted with DBS directional leads in two Italian centers (Udine and Vicenza) were retrospectively evaluated. Data were collected before starting stimulation (in the operating room and at days 5 and 40) and after switching stimulation on at the successive follow-up visits (1, 6 and 12 months).ResultsDirectional leads have significantly higher impedance than ring leads. Stimulated contacts had always lower impedance compared to non-stimulated contacts. Before DBS-on, all contacts had higher impedance in the operating room, with an initial decrease five days post-surgery and a subsequent increase at day 40, more evident for directional contacts. The impedance of directional leads increased post-implantation at 1 and 6 months with a plateau at 12 months.ConclusionsThere was a significant difference between the directional and ring leads at baseline (before activation of DBS) and during follow-up (chronic DBS).SignificanceOur study reveals new information about the impedance of segmented electrodes that is useful for patient management during the initial test period, as well as during long-term DBS follow-up.  相似文献   
26.
27.
BackgroundResearchers have proposed that impaired sleep may be a causal link in the progression from Mild Cognitive Impairment (MCI) to Alzheimer's Disease (AD). Several recent findings suggest that enhancing deep sleep (N3) may improve neurological health in persons with MCI, and buffer the risk for AD. Specifically, Transcranial Electrical Stimulation (TES) of frontal brain areas, the inferred source of the Slow Oscillations (SOs) of N3 sleep, can extend N3 sleep duration and improve declarative memory for recently learned information. Recent work in our laboratory using dense array Electroencephalography (dEEG) localized the sources of SOs to anterior limbic sites – suggesting that targeting these sites with TES may be more effective for enhancing N3.MethodsFor the present study, we recruited 13 healthy adults (M = 42 years) to participate in three all-night sleep EEG recordings where they received low level (0.5 mA) TES designed to target anterior limbic areas and a sham stimulation (placebo). We used a convolutional neural network, trained and tested on professionally scored EEG sleep staging, to predict sleep stages for each recording.ResultsWhen compared to the sham session, limbic-targeted TES significantly increased the duration of N3 sleep. TES also significantly increased spectral power in the 0.5–1 Hz frequency band (relative to pre-TES epochs) in left temporoparietal and left occipital scalp regions compared to sham.ConclusionThese results suggest that even low-level TES, when specifically targeting anterior limbic sites, can increase deep (N3) sleep and thereby contribute to healthy sleep quality.  相似文献   
28.
赵智勇  张娜 《医学综述》2015,21(1):135-136
目的探讨嵌顿痔不同治疗方法的疗效。方法回顾性分析2009年8月至2012年8月迁西县人民医院确诊为嵌顿痔的160例患者的临床资料,其中采取外剥内扎法的80例患者作为A组,吻合器痔上黏膜环切术(PPH)结合外痔血栓剥除术的80例患者作为B组。对比分析两组患者的手术时间、住院时间、住院费用等指标及临床疗效,对比分析两组术后6个月并发症发生情况。结果B组患者的手术时间、住院时间显著少于A组[(15.4±1.1)min比(38.7±0.5)min,(5.3±0.6)d比(12.4±1.3)d,P<0.01];B组患者的有效率显著高于A组(88.8%比66.3%),而总体并发症发生率及复发率显著低于A组(17.5%比33.8%,5%比18.8%,P<0.05)。结论 PPH结合外痔血栓剥除术临床疗效显著。  相似文献   
29.
IntroductionScales for predicting venous thromboembolism (VTE) recurrence are useful for deciding the duration of the anticoagulant treatment. Although there are several scales, the most appropriate for our setting has not been identified. For this reason, we aimed to validate the DASH prediction score and the Vienna nomogram at 12 months.MethodsThis was a retrospective study of unselected consecutive VTE patients seen between 2006 and 2014. We compared the ability of the DASH score and the Vienna nomogram to predict recurrences of VTE. The validation was performed by stratifying patients as low-risk or high-risk, according to each scale (discrimination) and comparing the observed recurrence with the expected rate (calibration).ResultsOf 353 patients evaluated, 195 were analyzed, with an average age of 53.5 ± 19 years. There were 21 recurrences in 1 year (10.8%, 95% CI: 6.8%-16%). According to the DASH score, 42% were classified as low risk, and the rate of VTE recurrence in this group was 4.9% (95% CI: 1.3%-12%) vs. the high-risk group that was 15% (95% CI: 9%-23%) (p <.05). According to the Vienna nomogram, 30% were classified as low risk, and the rate of VTE recurrence in the low risk group vs. the high risk group was 4.2% (95% CI:0.5%-14%) vs. 16.2% (95% CI: 9.9%-24.4%) (p <.05).ConclusionsOur study validates the DASH score and the Vienna nomogram in our population. The DASH prediction score may be the most advisable, both because of its simplicity and its ability to identify more low-risk patients than the Vienna nomogram (42% vs. 30%).  相似文献   
30.

Objective

Hypertonic saline (HTS) has potent immune and vascular effects. We assessed recipient pretreatment with HTS on allograft function in a porcine model of heart transplantation and hypothesized that HTS infusion would limit endothelial and left ventricular (LV) dysfunction following transplantation.

Methods

Heart transplants were performed after 6 hours of cold ischemic storage. Recipient pigs were randomized to treatment with or without HTS (7.5% NaCl) before cardiopulmonary bypass (CPB). Using a myograft apparatus, coronary artery endothelial-dependent (Edep) and -independent (Eind) relaxation was assessed. LV performance was determined using pressure-volume loop analysis. Pulmonary interleukin (IL)-2, IL-6, and tumor necrosis factor (TNF)-α expression was measured.

Results

Weaning from CPB and LV performance after transplantation were improved in HTS-treated animals. Successful weaning from CPB was greater in the HTS-treated hearts (8 of 8 vs 2 of 8; P < .05). Mean LV functional recovery was improved in the HTS-treated animals, as assessed by preload recruitable stroke work (65 ± 10% vs 27 ± 10%; P < .001) and end-systolic elastance (55 ± 7% vs 37 ± 4%; P < .001). Treatment with HTS resulted in improved Edep (mean maximum elastance [Emax], 56 ± 5% vs 37 ± 7%; P < .001) and Eind (mean Emax%, 77 ± 6% vs 52 ± 4%; P < .001) vasorelaxation compared with control. Pulmonary expression of IL-2, IL-6, and TNF-α increased following transplantation, whereas HTS therapy attenuated IL production (P < .001). Transplantation increased plasma TNF-α levels and LV TNF-α expression, whereas HTS prevented this up-regulation (P < .001).

Conclusions

Recipient HTS pretreatment preserves allograft vasomotor and LV function, and HTS therapy limits CPB-induced injury. HTS may be a novel recipient intervention to prevent graft dysfunction.  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