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   8609篇
  免费   848篇
  国内免费   44篇
耳鼻咽喉   107篇
儿科学   218篇
妇产科学   268篇
基础医学   1164篇
口腔科学   124篇
临床医学   784篇
内科学   1970篇
皮肤病学   130篇
神经病学   883篇
特种医学   279篇
外科学   1170篇
综合类   263篇
一般理论   6篇
预防医学   561篇
眼科学   194篇
药学   537篇
中国医学   37篇
肿瘤学   806篇
  2023年   66篇
  2022年   107篇
  2021年   244篇
  2020年   185篇
  2019年   251篇
  2018年   245篇
  2017年   174篇
  2016年   201篇
  2015年   256篇
  2014年   323篇
  2013年   386篇
  2012年   554篇
  2011年   564篇
  2010年   310篇
  2009年   278篇
  2008年   467篇
  2007年   449篇
  2006年   444篇
  2005年   392篇
  2004年   376篇
  2003年   379篇
  2002年   310篇
  2001年   242篇
  2000年   231篇
  1999年   203篇
  1998年   94篇
  1997年   63篇
  1996年   63篇
  1995年   62篇
  1994年   54篇
  1993年   49篇
  1992年   146篇
  1991年   135篇
  1990年   128篇
  1989年   112篇
  1988年   99篇
  1987年   100篇
  1986年   84篇
  1985年   95篇
  1984年   69篇
  1983年   47篇
  1982年   40篇
  1981年   37篇
  1980年   29篇
  1979年   38篇
  1978年   36篇
  1977年   38篇
  1976年   25篇
  1975年   33篇
  1974年   29篇
排序方式: 共有9501条查询结果,搜索用时 218 毫秒
91.
BACKGROUND CONTEXTSleep disturbance is highly prevalent in patients with spinal cord injury and is one of the most important clinical issues affecting their quality of life. However, it has not been properly measured or treated in patients with cervical myelopathy (CM), although most typical or atypical symptoms of CM are known to be risk factors for sleep disturbance. In addition, previous studies identified that the presence of sleep disturbance is unintentionally missed under the current evaluation process for degenerative spinal disease without direct investigation using validated tools for sleep. Therefore, studies about sleep disturbances in patients with CM are essential.PURPOSEThe purpose of this study was to investigate the prevalence of sleep disturbance in patients with CM using validated tools and to understand its mechanism by identifying high-risk patients.STUDY DESIGN/SETTINGCross-sectional study.PATIENT SAMPLEConsecutive patients diagnosed with CM.OUTCOME MEASURESPittsburgh sleep quality index.METHODSThis study was performed on patients diagnosed with CM. Sleep disturbance was determined using the Pittsburgh sleep quality index. Variables associated with sleep disturbance including demographics, lifestyle, medical history, and radiologic parameters were investigated. Independent risk factors related to sleep disturbance were identified using multivariate logistic regression analysis.RESULTSA total of 203 patients with CM were included in our study. Among them, 126 patients (62.1%) were men, and the mean age was 63.0 years. Despite male predominance, sleep disturbance was identified in 71.4% of patients (145 of 203). Multivariate analysis identified a worse depression scale score, a lower modified Japanese Orthopedic Association score, chronic shoulder joint pain, smaller spinal cord area, and decreased cervical range of motion as independent risk factors for sleep disturbance.CONCLUSIONSIn patients with CM, sleep disturbance was associated with a more severe type of myelopathy. Further studies including polysomnography and measurement of melatonin will be helpful to identify the mechanisms of the sleep disturbance in patients with CM and to improve their quality of life and clinical outcomes.  相似文献   
92.
ObjectivesThis study aims to: (i) evaluate the outcome of patients with Harrington class III lesions who were treated according to Harrington classification; (ii) propose a modified surgical classification for Harrington class III lesions; and (iii) assess the efficiency of the proposed modified classification.MethodsThis study composes two phases. During phase 1 (2006 to 2011), the clinical data of 16 patients with Harrington class III lesions who were treated by intralesional excision followed by reconstruction of antegrade/retrograde Steinmann pins/screws with cemented total hip arthroplasty (Harrington/modified Harrington procedure) were retrospectively reviewed and further analyzed synthetically to design a modified surgical classification system. In phase 2 (2013 to 2019), 62 patients with Harrington class III lesions were classified and surgically treated according to our modified classification. Functional outcome was assessed using the Musculoskeletal Tumor Society (MSTS) 93 scoring system. The outcome of local control was described using 2‐year recurrence‐free survival (RFS). Owing to the limited sample size, we considered P < 0.1 as significant.ResultsIn phase 1, the mean surgical time was 273.1 (180 to 390) min and the mean intraoperative hemorrhage was 2425.0 (400.0 to 8000.0) mL, respectively. The mean follow‐up time was 18.5 (2 to 54) months. Recurrence was found in 4 patients and the 2‐year RFS rate was 62.4% (95% confidence interval [CI] 31.6% to 93.2%). The mean postoperative MSTS93 score was 56.5% (20% to 90%). Based on the periacetabular bone destruction, we categorized the lesions into two subgroups: with the bone destruction distal to or around the inferior border of the sacroiliac joint (IIIa) and the bone destruction extended proximal to inferior border of the sacroiliac joint (IIIb). Six patients with IIIb lesions had significant prolonged surgical time (313.3 vs 249.0 min, P = 0.022), massive intraoperative hemorrhage (3533.3 vs 1760.0 mL, P = 0.093), poor functional outcome (46.7% vs 62.3%, P = 0.093), and unfavorable local control (31.3% vs 80.0%, P = 0.037) compared to the 10 patients with IIIa lesions. We then modified the surgical strategy for two subgroup of class III lesions: Harrington/modified Harrington procedure for IIIa lesions and en bloc resection followed by modular hemipelvic endoprosthesis replacement for IIIb lesions. Using the proposed modified surgical classification, 62 patients in the phase 2 study demonstrated improved surgical time (245.3 min, P = 0.086), intraoperative hemorrhage (1466.0 mL, P = 0.092), postoperative MSTS 93 scores (65.3%, P = 0.067), and 2‐year RFS rate (91.3%, P = 0.002) during a mean follow‐up time of 19.9 (1 to 60) months compared to those in the phase 1 study.ConclusionThe Harrington surgical classification is insufficient for class III lesions. We proposed modification of the classification for Harrington class III lesions by adding two subgroups and corresponding surgical strategies according to the involvement of bone destruction. Our proposed modified classification showed significant improvement in functional outcome and local control, along with acceptable surgical complexity in surgical management for Harrington class III lesions.  相似文献   
93.
The interaction between eating disorders and non-alcoholic fatty liver disease (NAFLD) remains unexplored, especially with regards to binge-eating disorder (BED). Our team conducted a service evaluation project in order to assess risk factors for the presence of BED among patients with NAFLD and the impact of BED on body mass composition. The overall prevalence of patients screening positive to BED Screener-7 (BEDS-7) was 28.4%, while a previous diagnosis of depression and marital status (as single or separated) were independently associated with positive BED. Furthermore, patients with positive BEDS-7 had higher BMI, with greater visceral component and overall lower muscle mass. There was no difference in terms of liver disease severity as assessed by noninvasive markers of fibrosis. However, as body mass composition and sarcopenia have been shown to be associated to disease progression in patients with NAFLD, further studies are required to ascertain the long-term impact of BED in these patients. Moreover, further work is warranted to identify to implement multidisciplinary approach within clinical psychology for the management of patients with BED, who may be particularly challenging in terms of achieving lifestyle modifications. As a hepatology community, we should address NAFLD with a more holistic approach.  相似文献   
94.
目的研究血管粘弹性对脉动血流在(扌衮)法推拿作用下切应力的影响.方法建立具有局部轴向运动狭窄的粘弹性血管中脉动血流模型.设血液为牛顿流体,血管壁为线性粘弹体.在(扌衮)法推拿作用下血管受水平外力作用形成轴向运动缓变狭窄,血流遵循线化Navier-stokes方程.结果粘弹性血管在(扌衮)法作用下,距离血管入口z=31 cm处的平均切应力、最大切应力和瞬时切应力以及最大狭窄下游血管段最大切应力随着血管粘性系数和手法频率的改变而有较大变化.结论(扌衮)法推拿作用下粘弹性血管的血管切应力有显著变化,这与中医推拿的活血化淤相吻合.  相似文献   
95.
Guidelines are an important means by which professional associations and governments have sought to improve the quality and cost-effectiveness of disease management for infectious diseases. Prescribing of initial antibiotic therapy for community-acquired respiratory tract infections (RTIs) is primarily empiric and physicians may often have a limited appreciation of bacterial resistance. Recent guidelines for managing RTIs have adopted a more evidence-based approach. This process has highlighted important gaps in the existing knowledge base, e.g. concerning the impact of resistance on the effectiveness of oral antibiotics for outpatient community-acquired pneumonia and the level of resistance that should prompt a change in empiric prescribing. In upper RTIs, the challenge is to identify patients in whom antibiotic therapy is warranted. Concentrated, sustained efforts are needed to secure physicians' use of guidelines. The information should be distilled into a simple format available at the point of prescribing and supported by other behavioral change techniques (e.g. educational outreach visits). Advances in information technology offer the promise of more dynamic, computer-assisted forms of guidance. Thus, RTI prescribing guidelines and other prescribing support systems should help control bacterial resistance in the community. However, their effect on resistance patterns is largely unknown and there is an urgent need for collaborative research in this area. Rapid, cost-effective diagnostic techniques are also required and new antibiotics will continue to have a role in disease management.  相似文献   
96.
We describe our experience with operative therapy for atrioventricular (AV) node tachycardia using an anatomically guided procedure. The operative rationale was to dissect the AV node from most of its atrial inputs (AV node "skeletonization") with the intent of altering the perinodal substrate and preventing reentry. The anteroseptal and posteroseptal regions were initially approached epicardially to facilitate identification of anatomical structures. Under normothermic cardiopulmonary bypass, the right atrial septum was mobilized and the intermediate AV node was exposed anterior to the tendon of Todaro. Atrioventricular node conduction was monitored electrocardiographically throughout the procedure. Ablation of concomitant accessory pathways was done prior to AV node skeletonization. Thirty-two patients aged 9 to 67 years (mean age, 30 years) underwent operation. Five patients had concomitant accessory pathways in addition to AV node reentry. At electrophysiological study before discharge, no patient had AV block although anterograde and retrograde Wenckebach cycle lengths were significantly prolonged. Six patients had retrograde AV block. Twenty-nine patients are free from arrhythmia and require no antiarrhythmic medication after a follow-up of 1 month to 45 months (mean follow-up, 17 months). Three patients had recurrence of tachycardia ten days, 2 months, and 7 months postoperatively. All patients subsequently had a successful reoperation.  相似文献   
97.
ReSllm6 Objectif Nos studes Precedentes out montrd une panne fonCtion de la greffe pulmonaire traitde Prdalablementper perfusion forcde retrograde et un stockage d froid inns ~. L' etude Prdsente a pour but de determiner l' effet de ~ surlefiot mngUin du poumon trait4 Prdalablement per perfusion retrograde forcde et un stockage d froid. met~. 12poumons donneurs canins out ate trait4s per perfusion r4tFograde de solution UW. Chez 6 animaux du grouch A, 250ng furent injectes dans l' artrdre…  相似文献   
98.
To delineate further the clinical phenotype of Lamb–Shaffer Syndrome (LSS) 16 unpublished patients with heterozygous variation in SOX5 were identified either through the UK Decipher database or the study team was contacted by clinicians directly. Clinical phenotyping tables were completed for each patient by their responsible clinical geneticist. Photos and clinical features were compared to assess key phenotypes and genotype–phenotype correlation. We report 16 SOX5 variants all of which meet American College of Medical Genetics/Association for Clinical Genomic Science ACMG/ACGS criteria class IV or V. 7/16 have intragenic deletions of SOX5 and 9/16 have single nucleotide variants (including both truncating and missense variants). The cohort includes two sets of monozygotic twins and parental gonadal mosaicism is noted in one family. This cohort of 16 patients is compared with the 71 previously reported cases and corroborates previous phenotypic findings. As expected, the most common findings include global developmental delay with prominent speech delay, mild to moderate intellectual disability, behavioral abnormalities and sometimes subtle characteristic facial features. We expand in more detail on the behavioral phenotype and observe that there is a greater tendency toward lower growth parameters and microcephaly in patients with single nucleotide variants. This cohort provides further evidence of gonadal mosaicism in SOX5 variants; this should be considered when providing genetic counseling for couples with one affected child and an apparently de novo variant.  相似文献   
99.
  1. Recently, 4-chloro-3-ethyl phenol (CEP) has been shown to cause the release of internally stored Ca2+, apparently through ryanodine-sensitive Ca2+ channels, in fractionated skeletal muscle terminal cisternae and in a variety of non-excitable cell types. Its action on smooth muscle is unknown. In this study, we characterized the actions of CEP on vascular contraction in endothelium-denuded dog mesenteric artery. We also determined its ability to release Ca2+, by use of Ca2+ imaging techniques, on dog isolated mesenteric artery smooth muscle cells and on bovine cultured pulmonary artery endothelial cells.
  2. After phenylephrine-(PE, 10 μM) sensitive Ca2+ stores were depleted by maximal PE stimulation in Ca2+-free medium, the action of CEP on refilling of the emptied PE stores was tested, by first pre-incubating the endothelium-denuded artery in CEP for 15 min before Ca2+ was restored for a 30 min refilling period. At the end of this period, Ca2+ and CEP were removed, and the arterial ring was tested again with PE to assess the degree of refilling of the internal Ca2+ store.
  3. In a concentration-dependent manner (30, 100 and 300 μM), CEP significantly reduced the size of the post-refilling PE contraction (49.4, 28.9 and 5.7% of control, respectively) in Ca2+-free media. This suggests that Ca2+ levels are reduced in the internal stores by CEP treatment. CEP alone did not cause any contraction either in Ca2+-containing or Ca2+-free Krebs solution.
  4. Restoring Ca2+ in the presence of PE caused a large contraction, which reflects PE-induced influx of extracellular Ca2+. The contraction of tissues pretreated with 300 μM CEP was significantly less compared with controls. However, tissues pretreated with 30 and 100 μM CEP were unaffected. Washout of CEP over 30 min produced complete recovery of responses to PE in Ca2+-free and Ca2+-containing medium suggesting a rapid reversal of CEP effects.
  5. Concentration-response curves were constructed for PE, 5-hydroxytryptamine (5-HT) and K+ in the absence of and after 30 min pre-incubation with 30, 100 and 300 μM CEP. In all cases, CEP caused a concentration-dependent depression of the maximum response to PE (84.8, 43.4 and 11.6% of control), 5-HT (65.4, 25.7 and 6.9% of control) and K+ (77.6, 41.1 and 10.8% of control).
  6. Some arterial rings were pre-incubated with ryanodine (30 μM) for 30 min before the construction of PE concentration-response curves. In Ca2+-free Krebs solution, ryanodine alone did not cause any contraction. However, 58% (11 out of 19) of the tissues tested with ryanodine developed contraction (6.9±1.2% of 100 mM K+ contraction, n=11) in the presence of external Ca2+. EC50 values for PE in ryanodine-treated tissues (1.7±0.25 μM, n=16) were not significantly different from controls (2.5±0.41 μM, n=22). Maximum contractions to PE (118.5±4.4% of 100 mM K+ contraction, n=16) were also unaffected by ryanodine when compared to controls (129±4.2%, n=23).
  7. When fura-2 loaded smooth muscle cells (n=13) and endothelial cells (n=27) were imaged for Ca2+ distribution, it was observed that 100 and 300 μM CEP in Ca2+-free medium caused Ca2+ release in both cell types. Smooth muscle cells showed a small decrease in cell length. Addition of EGTA (5 mM) reversed the effect of CEP on intracellular Ca2+ to control values.
  8. These data show, for the first time in vascular smooth muscle and endothelial cells, that CEP releases Ca2+ more rapidly than ryanodine. Unlike ryanodine, CEP caused no basal contraction but depressed contractions to PE, 5-HT and K+. The lack of basal contraction may result from altered responsiveness of the contractile system to intracellular Ca2+ elevation.
  相似文献   
100.
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