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   32412篇
  免费   3068篇
  国内免费   882篇
耳鼻咽喉   303篇
儿科学   957篇
妇产科学   428篇
基础医学   2963篇
口腔科学   317篇
临床医学   4396篇
内科学   4796篇
皮肤病学   290篇
神经病学   6655篇
特种医学   844篇
外国民族医学   4篇
外科学   5639篇
综合类   3298篇
预防医学   1458篇
眼科学   368篇
药学   2060篇
  29篇
中国医学   1056篇
肿瘤学   501篇
  2024年   26篇
  2023年   617篇
  2022年   913篇
  2021年   1603篇
  2020年   1691篇
  2019年   1481篇
  2018年   1419篇
  2017年   1471篇
  2016年   1397篇
  2015年   1328篇
  2014年   2267篇
  2013年   2647篇
  2012年   1690篇
  2011年   1836篇
  2010年   1482篇
  2009年   1531篇
  2008年   1471篇
  2007年   1369篇
  2006年   1395篇
  2005年   1135篇
  2004年   991篇
  2003年   848篇
  2002年   679篇
  2001年   635篇
  2000年   480篇
  1999年   392篇
  1998年   290篇
  1997年   281篇
  1996年   255篇
  1995年   270篇
  1994年   253篇
  1993年   212篇
  1992年   221篇
  1991年   175篇
  1990年   158篇
  1989年   153篇
  1988年   137篇
  1987年   100篇
  1986年   128篇
  1985年   171篇
  1984年   165篇
  1983年   117篇
  1982年   119篇
  1981年   85篇
  1980年   80篇
  1979年   52篇
  1978年   43篇
  1977年   30篇
  1976年   25篇
  1973年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
目的 通过4DCT(four-dimensional CT)动态评估咽鼓管功能障碍(Eustachian tube dysfuction,ETD)患者Valsava动作时的咽鼓管(Eustachian tube,ET)功能。方法 2018年11月~2019年3月期间就诊于首都医科大学附属北京安贞医院的ETD患者15例,无中耳疾病的志愿者15名。使用咽鼓管测压(tubomanometry,TMM),七项咽鼓管功能障碍评分量表(the seven-item Eustachian tube dysfunction questionnaire,ETDQ-7)和咽鼓管评分量表-7(the Eustachian tube score-7,ETS-7)等方法对所有对象咽鼓管功能做初步评价。嘱患者做Valsava动作,行ADCT动态扫描,记录ET开放过程,重建图像。测量ET数值,判断阻塞部位,进行统计学分析。结果 正常对照组可观察到ET全长,ETD组均有不同程度的阻塞。ETD组ET长度和角度显著大于对照组[(44.41±2.21)mm vs(40.60±2.20)mm,P<0.01;(168.73±4.66)mm vs(162.88±5.44)mm,P <0.01],前鼓室部直径显著小于对照组[(3.5±0.8)mm vs(5.3±1.1)mm,P <0.001]。结论 ET长度越长、角度越大,越容易发生ETD。ADCT动态扫描可准确评估ETD患者ET阻塞部位,对咽鼓管球囊扩张术适应证具有指导意义,辐射剂量低,可作为ET常规检查方法。  相似文献   
2.
ObjectiveThe use of mechanical circulatory support (MCS) in lung transplantation has been steadily increasing over the prior decade, with evolving strategies for incorporating support in the preoperative, intraoperative, and postoperative settings. There is significant practice variability in the use of these techniques, however, and relatively limited data to help establish institutional protocols. The objective of the AATS Clinical Practice Standards Committee (CPSC) expert panel was to review the existing literature and establish recommendations about the use of MCS before, during, and after lung transplantation.MethodsThe AATS CPSC assembled an expert panel of 16 lung transplantation physicians who developed a consensus document of recommendations. The panel was broken into subgroups focused on preoperative, intraoperative, and postoperative support, and each subgroup performed a focused literature review. These subgroups formulated recommendation statements for each subtopic, which were evaluated by the entire group. The statements were then developed via discussion among the panel and refined until consensus was achieved on each statement.ResultsThe expert panel achieved consensus on 36 recommendations for how and when to use MCS in lung transplantation. These recommendations included the use of veno-venous extracorporeal membrane oxygenation (ECMO) as a bridging strategy in the preoperative setting, a preference for central veno-arterial ECMO over traditional cardiopulmonary bypass during the transplantation procedure, and the benefit of supporting selected patients with MCS postoperatively.ConclusionsAchieving optimal results in lung transplantation requires the use of a wide range of strategies. MCS provides an important mechanism for helping these critically ill patients through the peritransplantation period. Despite the complex nature of the decision making process in the treatment of these patients, the expert panel was able to achieve consensus on 36 recommendations. These recommendations should provide guidance for professionals involved in the care of end-stage lung disease patients considered for transplantation.  相似文献   
3.
4.
Toxicity resulting from off-target effects, beyond acetylcholine esterase inhibition, for the commonly used organophosphate (OP) insecticides chlorpyrifos (CPS) and malathion (MA) was investigated using Saccharomyces cerevisiae and Caenorhabditis elegans model systems. Mitochondrial damage and dysfunction were observed in yeast following exposure to CPS and MA, suggesting this organelle is a major target. In the C. elegans model, the mitochondrial unfolded protein response pathway showed the most robust induction from CPS and MA treatment among stress responses examined. GABAergic neurodegeneration was observed with CPS and MA exposure. Impaired movement observed in C. elegans exposed to CPS and MA may be the result of motor neuron damage. Our analysis suggests that stress from CPS and MA results in mitochondrial dysfunction, with GABAergic neurons sensitized to these effects. These findings may aid in the understanding of toxicity from CPS and MA from high concentration exposure leading to insecticide poisoning.  相似文献   
5.
目的:探讨穴位气压疗法配合康复训练对帕金森病病人运动能力及自理能力的影响。方法:选取2020年3月—2021年5月医院收治的64例帕金森病病人为研究对象,采用随机数字表法分为对照组和试验组各32例,两组病人均给予常规治疗和规律的康复训练,试验组在此基础上联合穴位气压治疗仪辅助治疗,比较两组病人运动功能(UPDRS-Ⅲ评分)和生活自理能力(Barthel评分)变化。结果:干预10周后,两组病人的运动功能和生活自理能力均提高,但试验组UPDRS-Ⅲ评分明显低于对照组,Barthel评分明显高于对照组(P<0.001)。结论:穴位气压疗法配合康复训练可以明显改善帕金森病病人的运动功能,提高病人的生活自理能力,从而改善其生活质量。  相似文献   
6.
目的 探讨外周血单核细胞髓样分化因子88(My D88)与Toll样受体4(TLR4)在早产儿窒息后多器官功能障碍综合征(MODS)中的表达,为早产儿窒息后MODS的早期诊断及预后评估提供新思路。方法 连续性纳入2019年1月-2020年12月唐山市妇幼保健院新生儿科收治的115例窒息早产儿进行前瞻性研究,按照1 min Apgar评分将窒息早产儿分为轻度窒息组(n=70)与重度窒息组(n=45),以同期的50例健康早产儿作为对照组。比较3组早产儿中MODS发生率、MODS病死率及单器官损害发生率,外周血单核细胞My D88 mRNA及蛋白与TLR4 mRNA及蛋白的表达水平。结果 重度窒息组、轻度窒息组与对照组的MODS发生率分别为73.33%、31.43%、6.00%,MODS病死率分别为24.44%、5.71%、0,3组间比较差异有统计学意义(χ2=47.845、16.978,P<0.001);重度窒息组与轻度窒息组的单器官损害发生率明显高于对照组(P<0.05),重度窒息组明显高于轻度窒息组(P<0.05);重度窒息组与轻度窒息组的My D88 mRNA及蛋白与TLR4 mRNA及蛋白均明显高于对照组,且重度窒息组明显高于轻度窒息组(F=4.251、4.804、4.772、4.690,P<0.001)。结论 早产儿窒息后MODS发生率、外周血单核细胞My D88与TLR4表达水平均明显增高,My D88与TLR4有望成为早产儿窒息后MODS的早期诊断及预后评估指标。  相似文献   
7.
8.
ObjectiveDeterioration of the native aortic valve function by a late progression of rheumatic disease is not infrequent in patients who underwent rheumatic mitral valve surgery; however, this phenomenon has not been clearly quantified.MethodsA total of 1155 consecutive patients (age 52.0 ± 12.9 years; 807 female) who underwent rheumatic mitral valve surgery without concomitant aortic valve surgery from 1997 to 2015 were enrolled. The primary end point was the composite of progression to severe aortic valve dysfunction or a requirement of subsequent aortic valve replacements during follow-up. To determine the risk factors of the primary outcome, we performed the generalized linear mixed model.ResultsThe baseline severities of aortic valve were none to trivial in 880 patients (76.2%), mild in 256 patients (22.2%), and moderate in 19 patients (1.6%). The latest 1062 echocardiographic assessments (91.9%; median, 81.2 postoperative months; interquartile range, 37.3-132.1 months) demonstrated 26 cases (0.33%/patient-year) meeting the primary end point during follow-up. Cumulative incidence of the primary end point at 10 years was 0.4% ± 0.3% and 7.4% ± 2.5% depending on the presence of mild or greater aortic valve dysfunction at baseline (P < .01). In multivariable analyses, aortic valve peak pressure gradient (odds ratio, 1.14; 95% confidence interval, 1.10-1.20), aortic regurgitation degree (mild over none: odds ratio, 3.26; 95% confidence interval, 1.15-9.23), and time (odds ratio, 1.30; 95% confidence interval 1.19-1.41) were significantly associated with the occurrence of the primary end point.ConclusionsProgression of severe aortic valve dysfunction and the need for aortic valve replacement are uncommon in patients undergoing rheumatic mitral valve surgery. However, such events were relatively common among those with mild or greater aortic valve dysfunction at the time of mitral valve surgery.  相似文献   
9.
目的 探讨经阴道分娩所致耻骨损伤与耻尾肌损伤的发生差异以及2种损伤严重程度的相关性。 方法 回顾性分析88例初产妇经阴道分娩后的盆腔MRI影像。根据MR影像上有无耻骨损伤,将产妇分为耻骨损伤组(51例)和无耻骨损伤组(37例)。由2名高年资放射科诊断医师在MRI影像上判断和评估耻骨及耻尾肌损伤情况,包括耻骨的骨髓水肿、骨折,以及耻尾肌水肿、撕裂和断裂,并对损伤程度进行评分。采用独立样本t检验、Mann-Whitney U检验、卡方检验及Fisher精确概率检验比较有无耻骨损伤的2组临床资料和影像表现,不同耻骨损伤程度间的耻尾肌损伤发生率比较采用Fisher精确概率检验。采用Kendall`s tau-b相关分析耻骨损伤程度与耻尾肌损伤程度的相关性。 结果 耻骨损伤组骨盆痛、压力性尿失禁及耻尾肌损伤发生率均高于无耻骨损伤组(均P<0.05)。耻骨损伤程度不同,其耻尾肌损伤发生率不同(P<0.05),耻骨骨折,重度、中度及轻度骨髓水肿产妇的耻尾肌损伤发生率依次减低。耻骨损伤程度与耻尾肌损伤程度呈正性线性相关(r=0.297,P=0.036)。 结论 经阴道分娩的初产妇如有耻骨损伤则往往伴发耻尾肌损伤,并且耻骨损伤越严重,耻尾肌损伤发生率越高、程度越重。  相似文献   
10.
This study evaluates the impact of tooth-borne Surgically Assisted Rapid Mandibular Expansion (SARME) on the temporomandibular joint (TMJ) function and condylar morphology.Medical records of patients who received a SARME between 2014 and 2018 are retrospectively reviewed concerning functional problems. Morphological changes of the condyles are analyzed by means of surface registration of 3D reconstructed CBCT scans preoperatively and one-year postoperatively, and correlated to functional outcome.In 68 patients data are complete. The risk of TMJ dysfunction is slightly increased from 18 to 25% at a mean of 14 months after SARME. This is attributed to an increase in the number of minor problems (75–82%). The presence of complaints before SARME is the only identifiable risk factor for also having complaints after the intervention (p = 0.0019). In one patient with pre-existent TMJ dysfunction complaints deteriorated after SARME. After SARME no cases of extended condylar resorption are described. There is no correlation between morphological condylar changes and the prevalence of TMJ dysfunction (p = 0.7121 for appositional and p = 0.3038 for resorptive changes). However, appositional and resorptive changes at the condylar head appear to correlate with growth potential, based on age, gender and skeletal deformity (p < 0.0001 and p = 0.0154 respectively).Within the limitations of the study it seems that SARME does not have a negative impact on TMJ function or condylar integrity and, therefore, the choice for or against this approach can be made without considering consequences for TMJ a major issue for the decision.  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