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   46609篇
  免费   2508篇
  国内免费   2016篇
耳鼻咽喉   842篇
儿科学   800篇
妇产科学   287篇
基础医学   3018篇
口腔科学   460篇
临床医学   5564篇
内科学   11249篇
皮肤病学   476篇
神经病学   1885篇
特种医学   834篇
外科学   4186篇
综合类   8311篇
一般理论   2篇
预防医学   3230篇
眼科学   161篇
药学   4813篇
  40篇
中国医学   4091篇
肿瘤学   884篇
  2024年   82篇
  2023年   745篇
  2022年   1631篇
  2021年   2147篇
  2020年   1831篇
  2019年   1588篇
  2018年   1542篇
  2017年   1547篇
  2016年   1845篇
  2015年   1824篇
  2014年   4197篇
  2013年   3793篇
  2012年   3450篇
  2011年   3759篇
  2010年   2925篇
  2009年   2484篇
  2008年   2275篇
  2007年   2221篇
  2006年   1820篇
  2005年   1463篇
  2004年   1088篇
  2003年   901篇
  2002年   666篇
  2001年   616篇
  2000年   528篇
  1999年   509篇
  1998年   372篇
  1997年   309篇
  1996年   290篇
  1995年   268篇
  1994年   259篇
  1993年   205篇
  1992年   198篇
  1991年   163篇
  1990年   185篇
  1989年   164篇
  1988年   142篇
  1987年   121篇
  1986年   106篇
  1985年   120篇
  1984年   120篇
  1983年   72篇
  1982年   92篇
  1981年   64篇
  1980年   95篇
  1979年   62篇
  1978年   50篇
  1977年   54篇
  1976年   44篇
  1974年   26篇
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
41.
42.

Background

Partial nephrectomy (PN) is generally favored for cT1 tumors over radical nephrectomy (RN) when technically feasible. However, it can be unclear whether the additional risks of PN are worth the magnitude of renal function benefit.

Objective

To develop preoperative tools to predict long-term estimated glomerular filtration rate (eGFR) beyond 30 d following PN and RN, separately.

Design, setting, and participants

In this retrospective cohort study, patients who underwent RN or PN for a single nonmetastatic renal tumor between 1997 and 2014 at our institution were identified. Exclusion criteria were venous tumor thrombus and preoperative eGFR <15 ml/min/1.73 m2.

Intervention

RN and PN.

Outcome measurements and statistical analysis

Hierarchical generalized linear mixed-effect models with backward selection of candidate preoperative features were used to predict long-term eGFR following RN and PN, separately. Predictive ability was summarized using marginal RGLMM2, which ranges from 0 to 1, with higher values indicating increased predictive ability.

Results and limitations

The analysis included 1152 patients (13 206 eGFR observations) who underwent RN and 1920 patients (18 652 eGFR observations) who underwent PN, with mean preoperative eGFRs of 66 ml/min/1.73 m2 (standard deviation [SD] = 18) and 72 ml/min/1.73 m2 (SD = 20), respectively. The model to predict eGFR after RN included age, diabetes, preoperative eGFR, preoperative proteinuria, tumor size, time from surgery, and an interaction between time from surgery and age (marginal RGLMM2=0.41). The model to predict eGFR after PN included age, presence of a solitary kidney, diabetes, hypertension, preoperative eGFR, preoperative proteinuria, surgical approach, time from surgery, and interaction terms between time from surgery and age, diabetes, preoperative eGFR, and preoperative proteinuria (marginal RGLMM2). Limitations include the lack of data on renal tumor complexity and the single-center design; generalizability needs to be confirmed in external cohorts.

Conclusions

We developed preoperative tools to predict renal function outcomes following RN and PN. Pending validation, these tools should be helpful for patient counseling and clinical decision-making.

Patient summary

We developed models to predict kidney function outcomes after partial and radical nephrectomy based on preoperative features. This should help clinicians during patient counseling and decision-making in the management of kidney tumors.  相似文献   
43.
ObjectiveThe purpose of this study was to evaluate the visibility of the anterolateral ligament (ALL) by magnetic resonance imaging (MRI) in patients with chronic anterior cruciate ligament (ACL) rupture.Materials and methodsThis retrospective case – control study compared 1.5 - T MRI scans for 50 patients with a chronic ACL rupture with those of a control group of 50 patients with an intact ACL. The ALL was evaluated in three portions: femoral, meniscal, and tibial. The status of each portion was classified as visualized or non-visualized. Two radiologists separately reviewed all the MRI scans to evaluate interobserver reliability.ResultsAt least one portion of the ALL was visualized in 100% of the control group and 72% of the chronic ACL rupture group. All three portions of the ALL were identified in 72% of the control group but only 10% of the chronic ACL rupture group. In both groups, the most commonly visualized portion was the meniscal portion and the least visualized was the tibial portion. In 18% of the chronic ACL rupture group, no portion of the ALL was visualized.ConclusionsThe visibility of the ALL of the knee was significantly lower in patients with a chronic ACL rupture than in those with an intact one.  相似文献   
44.
Context: We sought to describe our experience with the Hybrid Assistive Limb® (HAL®) for active knee extension and voluntary ambulation with remaining muscle activity in a patient with complete paraplegia after spinal cord injury.

Findings: A 30-year-old man with complete paraplegia used the HAL® for 1 month (10 sessions) using his remaining muscle activity, including hip flexor and upper limb activity. Electromyography was used to evaluate muscle activity of the gluteus maximus, tensor fascia lata, quadriceps femoris, and hamstring muscles in synchronization with the Vicon motion capture system. A HAL® session included a knee extension session with the hip flexor and voluntary gait with upper limb activity. After using the HAL® for one month, the patient’s manual muscle hip flexor scores improved from 1/5 to 2/5 for the right and from 2/5 to 3/5 for the left knee, and from 0/5 to 1/5 for the extension of both knees.

Conclusion/clinical relevance: Knee extension sessions with HAL®, and hip flexor and upper-limb-triggered HAL® ambulation seem a safe and feasible option in a patient with complete paraplegia due to spinal cord injury.  相似文献   

45.
《中国现代医生》2019,57(35):100-102+105
目的探讨多层螺旋CT(MSCT)定量评估慢性阻塞性肺疾病病情的价值。方法选取2017年8月~2018年7月在湖州市第一人民医院就诊的73例慢性阻塞性肺疾病(COPD)患者作为研究对象,按照病情轻重分为Ⅰ组(轻度患者17例)、Ⅱ组(中度患者32例)、Ⅲ组(重度患者24例),并选取同期于该院体检的健康者20例为对照组。所有研究对象均行MSCT低剂量扫描,观察比较各组管腔面积(Ai)、支气管壁面积百分比(WA%)、管壁厚度与体表面积比值(T/BSA)、壁厚度与直径比值(TDR),同时予以肺功能检查,采用定量CT气道分析软件分别测量气道相关参数,并用Siemens Pulmo软件Pearson定量分析其相关性。结果对照组、Ⅰ组、Ⅱ组、Ⅲ组的FEV1均呈逐渐下降趋势,FEV1/FVC呈逐渐上升趋势,差异均有统计学意义(P0.05)。对照组、Ⅰ组、Ⅱ组、Ⅲ组的WA%、T/BSA、TDR比较,均呈逐渐上升趋势,Ai呈下降趋势,差异均有统计学意义(P0.05)。FEV1与WA%、TDR之间呈负相关(r=-0.291,P=0.000;r=-0.473,P=0.000),FEV1/FVC与WA%、TDR之间呈正相关(r=0.285,P=0.000;r=0.472,P=0.000)。结论 MSCT扫描及定量分析可为COPD患者气道病变情况提供可靠的评估信息。  相似文献   
46.
ObjectiveGrowing evidence demonstrates that perceived discrimination and racism are significant contributing factors to psychological distress, low-grade chronic inflammation, and cardiovascular health disparities among minorities, particularly among Black women. Despite this evidence, there are no evidence-based complementary therapy interventions available to ameliorate chronic stress associated with racism and discrimination. The purpose of this study was to examine the feasibility and effectiveness of a novel, 8-week, group-based stress reduction program, Resilience, Stress and Ethnicity (RiSE), designed to help Black women at risk for cardiovascular disease (CVD) develop effective coping skills for dealing with chronic stress uniquely associated with being a minority.MethodsWe conducted two semi-structured focus groups with Black women (N = 22) following their participation in the 8-week RiSE program. We analyzed the data using constant comparative qualitative methods.ResultsAttrition rate was low (13%) with all participants attending at least 6 of the 8 classes. Participants reported high levels of satisfaction with the program and the majority (81%) reported practicing the skills that they learned in real-life stressful situations. In describing the participants’ response to the program, four key categories emerged from the data: (1) Increasing awareness of stressors associated with perceived discrimination and racism; (2) Coping with race-based stressors; (3) Coping with other sources of stress; and (4) Increasing sense of empowerment and emotion regulation.ConclusionsFindings suggest that RiSE is feasible and effective in helping Black women at risk for CVD cope with chronic stress associated with being a minority. Given evidence that perceived discrimination and racism are underlying factors in many inflammatory-based chronic diseases, this research may have broader implications for reducing health disparities across a wide-spectrum of chronic illnesses in which women minorities are disproportionately affected.  相似文献   
47.
Sickle cell disease (SCD) is a highly complex inherited disorder of hemoglobin structure. Although the molecular lesion is a single-point mutation, the sickle gene is pleiotropic in nature causing multiple phenotypic expressions that constitute the various complications of the disease. Its manifestations could be acute, chronic, nociceptive, neuropathic that could occur singly or in various combinations. Pain continues to be the major factor of SCD phenotypic complications and the most common cause of admissions to the Emergency Department and/or the hospital. Although progress has been made in understanding the pathophysiology of SCD as well as in developing curative therapies such as hematopoietic stem cell transplantation and gene therapy, effective pain management continues to lag behind. Palliative therapies continue to be the major approach to the management of SCD and its complications. The advent of hydroxyurea made partial success in preventing the frequency of vaso-occlusive crises and l-glutamine awaits post-trial confirmation of benefits. The search for additional pharmacotherapeutic agents that could be used singly or in combination with hydroxyurea and/or l-glutamine awaits their dawn hopefully in the near future. The purpose of this review is to describe the various manifestations of SCD, their pathophysiology and their current management. Recent impressive advances in understanding the pathophysiology of pain promise the determination of agents that could replace or minimize the use of opioids.  相似文献   
48.
BackgroundManagement of inflammatory bowel diseases (IBD) in the emergency department is often suboptimal.AimsTo develop a national consensus checklist of indicators to facilitate decision-making in emergency departments concerning hospitalisation and referral for abdominopelvic computed tomography (CT).MethodsA Delphi survey was used to obtain consensus on a checklist of clinical and biological variables. 119 healthcare professionals experienced in treating IBD were invited to participate. Panellists were provided with a literature survey and invited to agree or disagree with items on a prototype checklist. Two successive rounds of voting were organised.ResultsThe prototype checklist included fifteen clinical or laboratory indicators for hospitalisation or CT. Four indicators were not retained in the Delphi process and four additional indicators added. The final indicators retained were: abdominal signs/symptoms of disease exacerbation, intravenous morphine titration, fever, vomiting, dehydration, recent intestinal surgery, ano-perineal abscess, bowel obstruction, haemodynamic instability, anaemia, acute kidney failure and elevated C-reactive protein. Consensus for the retained indicators was >88%.ConclusionsUse of this consensus checklist for the management of IBD in the emergency department may help improve standards of care and thus reduce the burden of these diseases.  相似文献   
49.
Abstract

The purpose of this study was to investigate the strength of the relationships between self-efficacy and (i) functional exercise capacity and (ii) physical activity in chronic obstructive pulmonary disease (COPD), and whether self-efficacy assessment type (i.e., COPD symptoms, exercise-task, exercise-barrier, general, falls) and physical activity assessment type (i.e., self-report vs. objective) are moderators. A systematic search of COPD and self-efficacy concepts was conducted using eight databases from inception to 23 January 2019. Studies were included if they provided correlation coefficients of the relationship between self-efficacy and functional exercise capacity or physical activity, were conducted in adults diagnosed with COPD, and were published in English-language journals. A total of 14 correlation coefficients were included in the self-efficacy and functional exercise capacity meta-analysis, and 16 in the self-efficacy and physical activity meta-analysis. Data were screened, reviewed, and extracted independently by two reviewers, with discrepancies resolved by a third reviewer. Stronger self-efficacy was associated with better functional exercise capacity (weighted r?=?0.38, 95%CI [0.25, 0.50]), and greater physical activity (weighted r?=?0.25, 95%CI [0.17, 0.34]). Exercise-task self-efficacy had the strongest relationship to functional exercise capacity (weighted r?=?0.64, 95% CI [0.51, 0.73]). For physical activity, the type of self-efficacy most strongly related was inconclusive. In COPD, self-efficacy has a relationship to functional exercise capacity and physical activity, the strength of which is influenced by the choice of self-efficacy measure. An understanding of these relationships will assist clinicians in selecting the self-efficacy measure most closely related to the outcome of interest.  相似文献   
50.
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