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   1060篇
  免费   263篇
  国内免费   50篇
  2024年   5篇
  2023年   28篇
  2022年   43篇
  2021年   56篇
  2020年   63篇
  2019年   53篇
  2018年   46篇
  2017年   85篇
  2016年   67篇
  2015年   66篇
  2014年   112篇
  2013年   144篇
  2012年   64篇
  2011年   64篇
  2010年   50篇
  2009年   45篇
  2008年   37篇
  2007年   37篇
  2006年   40篇
  2005年   32篇
  2004年   24篇
  2003年   18篇
  2002年   22篇
  2001年   17篇
  2000年   14篇
  1999年   16篇
  1998年   9篇
  1997年   11篇
  1996年   10篇
  1995年   7篇
  1994年   6篇
  1993年   11篇
  1992年   7篇
  1991年   10篇
  1990年   6篇
  1989年   1篇
  1988年   7篇
  1987年   2篇
  1986年   3篇
  1985年   8篇
  1984年   7篇
  1983年   1篇
  1982年   4篇
  1981年   1篇
  1980年   5篇
  1979年   3篇
  1977年   2篇
  1975年   1篇
  1973年   2篇
  1972年   1篇
排序方式: 共有1373条查询结果,搜索用时 15 毫秒
31.
32.
摘要 目的:探讨与分析超声引导下腰方肌阻滞(quadratus lumborum block,QLB)复合气管插管全麻对于老年患者腹腔镜下全腹膜外(totally extraperitoneal prosthetic,TEP)腹股沟疝无张力修补术的影响,以促进该方法的临床使用。方法:2014年9月到2020年6月选择在本院诊治的腹股沟疝老年患者180例,根据随机数字表法分为QLB组与对照组各90例。所有患者都给予腹腔镜下全腹膜外腹股沟疝无张力修补术,对照组给予气管插管全麻,QLB组在对照组麻醉的基础上给予超声引导下QLB,记录两组镇痛与麻醉效果。结果:两组的术中出血量、手术时间等对比差异无统计学意义(P>0.05),QLB组的术后住院时间、术后胃肠功能恢复时间、术后下床活动时间显著短于对照组(P<0.05)。与术后12 h对比,两组术后24 h与36 h的疼痛VAS评分均降低(P<0.05),且QLB组术后12 h、24 h与36 h的疼痛VAS评分都显著低于对照组(P<0.05)。QLB组术后7 d的血肿、呼吸抑制、脏器损伤、腹股沟区包块等并发症发生率为8.9 %,显著低于对照组的21.1 %(P<0.05)。QLB组的瑞芬太尼用量、术后48 h内有效按压自控静脉镇痛泵次数、自控静脉镇痛泵累计用量都显著少于对照组(P<0.05)。结论:超声引导下QLB复合气管插管全麻在老年患者腹腔镜下全腹膜外腹股沟疝无张力修补术中的应用能提高镇痛与麻醉效果,减少术后并发症的发生,有利于促进患者康复。  相似文献   
33.
摘要 目的:探讨复方丹参滴丸联合沙库巴曲缬沙坦对老年心肌梗死患者经皮冠状动脉介入术(percutaneous coronary intervention,PCI)术后炎性反应、心室重塑和心肌灌注的影响。方法:采用随机数字表法将本院2017年3月至2020年2月间收治的行PCI治疗的68例老年心肌梗死为研究对象,分为对照组(34例)和观察组(34例)。两组均行常规药物治疗,在此基础上予以对照组沙库巴曲缬沙坦治疗,予以观察组复方丹参滴丸联合沙库巴曲缬沙坦治疗。比较两组治疗前后血浆中超敏C反应蛋白(high-sensitivity creactive protein,hs-CRP)、肿瘤坏死因子-α(Tumor necrosis factor-α,TNF-α)、白细胞介素-8(interleukin-8,IL-8)、N末端脑钠肽前体(N-terminal-pro-brain-natriuretic-peptide,NT-proBNP)、左室舒张末期前后径(left ventricular end-diastolic diamete,LVEDD)、左室射血分数(left ventricular ejection fraction,LVEF)、左室质量指数(left ventricular mass index,LVMI)以及治疗后TIMI血流分级。结果:两组血浆hs-CRP、TNF-α、IL-8和NT-proBNP水平以及LVEDD和LVMI水平较治疗前明显降低,LVEF水平明显增加(P<0.05)。观察组治疗后血浆hs-CRP、TNF-α、IL-8和NT-proBNP水平以及LVEDD和LVMI水平明显低于对照组,LVEF水平明显高于对照组(P<0.05)。两组术后20 minTIMI血流分级均明显好转,观察组术后20 min时TIMI血流分级明显优于对照组(P<0.05)。两组不良反应总发生率比较无明显差异(P>0.05)。结论:复方丹参滴丸联合沙库巴曲缬沙坦能够明显降低老年心肌梗死患者PCI术后炎性反应,抑制心室重塑,改善心肌灌注,安全性较高。  相似文献   
34.
目的:观察三重措施预防为基础,联合非阿片镇痛药复合静脉全麻在行鼾症手术患者术后恶心呕吐的应用效果。方法:选择择期行鼾症手术男性病人80例,随机分为两组:吸入麻醉组(inhalation group, IHLA组)和静脉麻醉组(intravenous group, TIVA组),每组40例,两组均采用三重措施预防恶心呕吐,IHLA组采用以舒芬太尼为基础复合七氟烷吸入麻醉,TIVA组以氯胺酮和右美托咪定镇痛基础上丙泊酚全凭静脉麻醉。评估两组病人恶心呕吐危险系数,采用李克特量表(Likert scale),记录并分析两组患者术后6~8 h在麻醉后监测治疗室(post anesthesia care unit, PACU)及病房24 h恶心呕吐发生情况及补救用药用量。结果:两组患者一般临床资料、恶心呕吐风险评分、手术时间、术后恢复期补救用药量人数无显著差异(P>0.05);IHLA组在PACU恶心呕吐发生率为39.5%,TIVA组发生率为18.9%,两者相比有显著性差异(P<0.05);IHLA组病房24 h恶心呕吐严重程度高于TIVA组,两组术后需要补救应用抗呕吐药物用量无显著差异(P>0.05)。结论:以三重措施预防为基础,与吸入麻醉相比,非阿片类镇痛药复合静脉麻醉可以减少肥胖病人鼾症手术术后恶心呕吐发生率和严重程度,降低围术期风险,有利于患者早期恢复。  相似文献   
35.
摘要 目的:瑞芬太尼、右美托咪定对全身麻醉下髋关节置换术患者的脑氧代谢、血流动力学和认知功能的影响。方法:选取2016年6月~2019年10月期间我院收治的100例行髋关节置换术的患者。采用随机数字表法分为对照组和研究组,各50例。对照组患者麻醉中予以瑞芬太尼,研究组则在对照组的基础上复合右美托咪定,比较两组患者血流动力学、脑氧代谢和认知功能情况,记录两组患者围术期间不良反应发生率。结果:两组手术开始后30 min(T1)~手术结束时(T2)时间点平均动脉压(MAP)、心率(HR)均呈下降趋势,但研究组高于对照组(P<0.05)。两组T1~T2时间点动脉血氧含量(CaO2)、颈内静脉血氧含量(CjvO2)均呈下降趋势,且研究组低于对照组(P<0.05);两组T1~T2时间点颈静脉球部血氧饱和度(SjvO2)呈升高趋势,且研究组高于对照组(P<0.05)。两组术前~术后7 d简明精神状态量表(MMSE)评分均呈下降后升高趋势(P<0.05);研究组术后3 d、术后7 d MMSE评分高于对照组(P<0.05)。研究组术后3 d、术后7 d的认知功能障碍(POCD)发生率低于对照组(P<0.05)。两组不良反应发生率比较无差异(P>0.05)。结论:全身麻醉下髋关节置换术患者麻醉方案选用右美托咪定联合瑞芬太尼,可减轻血流动力学波动,维持脑氧供需平衡,可减少POCD发生风险,且安全性较好。  相似文献   
36.
IntroductionAn in-house developed tool was implemented and validated to investigate the skin surface, hepatic dome, and target displacement for stereotactic ablative radiotherapy (SABR) of thoracic/abdominal lesions using a Surface Guided Radiation Therapy (SGRT) system combined with 4D- images.Materials and methodsFourteen consecutive patients with tumors near the hepatic dome undergoing SABR treatments were analyzed. For each patient, a planning 4D-CT and five 4D-CBCT images were acquired. The C-RAD technology was also used to register/monitor the position of the skin reference point (SRP) as an external marker representative of patient breathing. The 4D images were imported in the developed tool, and the absolute maximum height (Pmax,dome) of the hepatic dome on the ten respiratory phases was semi-automatically detected. Similarly, the contour of the skin surface was extracted in correspondence with the SRP position. The tool has been validated using an ad hoc modified moving phantom with pre-selected amplitudes and numbers of cycles. The Pearson correlation coefficients and Bland-Altman plots were calculated.ResultsThere was a strong correlation between the skin motion amplitude based on 4D-CBCT and the C-RAD in all the patients (0.90 ± 0.08). Similarly, the mean ± SD of Pearson correlation coefficients of skin and Pmax,dome movements registered by 4D-CT and 4D-CBCT were 0.90 ± 0.05 and 0.94 ± 0.05, respectively. The mean ± SD of Pearson correlation coefficients comparing the skin and Pmax,dome displacements within each imaging modality were 0.88 ± 0.05 and 0.90 ± 0.05 for 4D-CT and 4D-CBCT, respectively. The SRP displacement during the set-up imaging and the treatment delivery were similar in all the investigated patients. Similar results were obtained for the ad hoc modified phantom in the preliminary validation phase.ConclusionThe strong correlation between the tumor/ hepatic dome and skin displacements confirms that the SGRT approach can be considered appropriate for intra- and inter-fraction motion management in SABR therapy.  相似文献   
37.
ABSTRACT

Bacteria spend their lives buffeted by changing environmental conditions. To adapt to and survive these stresses, bacteria have global response systems that result in sweeping changes in gene expression and cellular metabolism. These responses are controlled by master regulators, which include: alternative sigma factors, such as RpoS and RpoH; small molecule effectors, such as ppGpp; gene repressors such as LexA; and, inorganic molecules, such as polyphosphate. The response pathways extensively overlap and are induced to various extents by the same environmental stresses. These stresses include nutritional deprivation, DNA damage, temperature shift, and exposure to antibiotics. All of these global stress responses include functions that can increase genetic variability. In particular, up-regulation and activation of error-prone DNA polymerases, down-regulation of error-correcting enzymes, and movement of mobile genetic elements are common features of several stress responses. The result is that under a variety of stressful conditions, bacteria are induced for genetic change. This transient mutator state may be important for adaptive evolution.  相似文献   
38.
Complex tissue culture matrices, in which types and concentrations of biological stimuli (e.g. growth factors, inhibitors, or small molecules) or matrix structure (e.g. composition, concentration, or stiffness of the matrix) vary over space, would enable a wide range of investigations concerning how these variables affect cell differentiation, migration, and other phenomena. The major challenge in creating layered matrices is maintaining the structural integrity of layer interfaces without diffusion of individual components from each layer1. Current methodologies to achieve this include photopatterning2-3, lithography4, sequential functionalization5, freeze drying6, microfluidics7, or centrifugation8, many of which require sophisticated instrumentation and technical skills. Others rely on sequential attachment of individual layers, which may lead to delamination of layers9. DGMP overcomes these issues by using an inert density modifier such as iodixanol to create layers of varying densities10. Since the density modifier can be mixed with any prepolymer or bioactive molecule, DGMP allows each scaffold layer to be customized. Simply varying the concentration of the density modifier prevents mixing of adjacent layers while they remain aqueous. Subsequent single step polymerization gives rise to a structurally continuous multilayered scaffold, in which each layer has distinct chemical and mechanical properties. The density modifier can be easily removed with sufficient rinsing without perturbation of the individual layers or their components. This technique is therefore well suited for creating hydrogels of various sizes, shapes, and materials.A protocol for fabricating a 2D-polyethylene glycol (PEG) gel, in which alternating layers incorporate RGDS-350, is outlined below. We use PEG because it is biocompatible and inert. RGDS, a cell adhesion peptide11, is used to demonstrate spatial restriction of a biological cue, and the conjugation of a fluorophore (Alexa Fluor 350) enables us to visually distinguish various layers. This procedure can be adapted for other materials (e.g. collagen, hyaluronan, etc.) and can be extended to fabricate 3D gels with some modifications10.  相似文献   
39.
Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we present the fabrication protocol for a multilayered SAW acoustic counterflow device. The device is fabricated starting from a lithium niobate (LN) substrate onto which two interdigital transducers (IDTs) and appropriate markers are patterned. A polydimethylsiloxane (PDMS) channel cast on an SU8 master mold is finally bonded on the patterned substrate. Following the fabrication procedure, we show the techniques that allow the characterization and operation of the acoustic counterflow device in order to pump fluids through the PDMS channel grid. We finally present the procedure to visualize liquid flow in the channels. The protocol is used to show on-chip fluid pumping under different flow regimes such as laminar flow and more complicated dynamics characterized by vortices and particle accumulation domains.  相似文献   
40.
Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta and inferior vena cava (IVC) are exposed. The proximal infrarenal aorta and the distal aorta are dissected for clamp placement and needle puncture, respectively. Special attention is paid to avoid dissection between the aorta and the IVC. After clamping the aorta, a 25 G needle is used to puncture both walls of the aorta into the IVC. The surrounding connective tissue is used for hemostatic compression. Successful creation of the AVF will show pulsatile arterial blood flow in the IVC. Further confirmation of successful AVF can be achieved by post-operative Doppler ultrasound.  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