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   45134篇
  免费   3333篇
  国内免费   1008篇
耳鼻咽喉   269篇
儿科学   866篇
妇产科学   1347篇
基础医学   4126篇
口腔科学   811篇
临床医学   4965篇
内科学   6840篇
皮肤病学   267篇
神经病学   1768篇
特种医学   1623篇
外国民族医学   9篇
外科学   3532篇
综合类   7081篇
现状与发展   1篇
预防医学   7170篇
眼科学   317篇
药学   4886篇
  106篇
中国医学   1718篇
肿瘤学   1773篇
  2024年   106篇
  2023年   636篇
  2022年   1274篇
  2021年   1840篇
  2020年   1710篇
  2019年   1474篇
  2018年   1515篇
  2017年   1469篇
  2016年   1558篇
  2015年   1483篇
  2014年   2976篇
  2013年   3084篇
  2012年   2787篇
  2011年   2989篇
  2010年   2258篇
  2009年   2068篇
  2008年   2032篇
  2007年   2152篇
  2006年   1744篇
  2005年   1574篇
  2004年   1350篇
  2003年   1119篇
  2002年   1021篇
  2001年   882篇
  2000年   773篇
  1999年   721篇
  1998年   587篇
  1997年   597篇
  1996年   566篇
  1995年   493篇
  1994年   487篇
  1993年   367篇
  1992年   393篇
  1991年   355篇
  1990年   292篇
  1989年   288篇
  1988年   251篇
  1987年   202篇
  1986年   191篇
  1985年   247篇
  1984年   211篇
  1983年   134篇
  1982年   183篇
  1981年   156篇
  1980年   139篇
  1979年   125篇
  1978年   97篇
  1977年   90篇
  1976年   86篇
  1975年   89篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.

Objective

To quantify the effects of initial hip angle and angular hip velocity settings of a lower-limb wearable robotic exoskeleton (WRE) on the balance control and mechanical energy requirements in patients with paraplegic spinal cord injuries (SCIs) during WRE-assisted sit-to-stand (STS).

Design

Observational, cross-sectional study.

Setting

A university hospital gait laboratory with an 8-camera motion analysis system, 3 forceplates, a pair of instrumented crutches, and a WRE.

Participants

Patients (N=12) with paraplegic SCI.

Interventions

Not applicable.

Main Outcome Measures

The inclination angle (IA) of the body’s center of mass (COM) relative to the center of pressure (COP), and the rate of change of IA (RCIA) for balance control, and the mechanical energy and forward COM momentum before and after seat-off for energetics during WRE-assisted STS were compared between conditions with 2 initial hip angles (105° and 115°) and 3 initial hip angular velocities (800, 1000, 1200 rpm).

Results

No interactions between the main factors (ie, initial hip angle vs angular velocity) were found for any of the calculated variables. Greater initial hip angle helped the patients with SCI move the body forward with increased COM momentum but reduced RCIA (P<.05). With increasing initial angular hip velocity, the IA and RCIA after seat-off (P<.05) increased linearly while total mechanical energy reduced linearly (P<.05).

Conclusions

The current results suggest that a greater initial hip angle with smaller initial angular velocity may provide a favorable compromise between momentum transfer and balance of the body for people with SCI during WRE-assisted STS. The current data will be helpful for improving the design and clinical use of the WRE.  相似文献   
992.

Objective

To evaluate the effect of pulmonary rehabilitation (PR) on exercise performance and quality of life in patients with chronic obstructive pulmonary disease (COPD) with different degrees of static lung hyperinflation (LH).

Design

Retrospective cohort study.

Setting

PR network.

Participants

A cohort of 1981 patients with COPD (55% men; age: 66.8±9.3y; forced expiratory volume in the first second%: 50.7±19.5; residual volume [RV]%: 163.0±49.7).

Intervention

An interdisciplinary PR program for patients with COPD consisting of 40 sessions.

Main Outcome Measures

Participants were stratified into 5 quintiles according to baseline RV and were evaluated on the basis of pre- and post-PR 6-minute walk distance (6MWD), constant work rate test (CWRT), and Saint George’s Respiratory Questionnaire (SGRQ), among other clinical parameters.

Results

With increasing RV quintile, patients were younger, more frequently women, had lower forced expiratory volume in the first second%, lower body mass index and fat-free mass index, shorter 6MWD, shorter CWRT, and worse SGRQ scores (P<.01). All RV strata improved after PR in all 3 outcomes (P<.001). Nevertheless, higher, compared to lower RV categories, had lower ΔCWRT (P<.01) but similar Δ6MWD (P=.948) and ΔSGRQ (P=.086) after PR.

Conclusions

LH in COPD is related to younger age, female sex, lower body weight, worse exercise capacity and health status, but did not prevent patients from benefitting from PR. LH, however, influences walking and cycling response after PR differently.  相似文献   
993.
994.
目的:分析该地区泌尿生殖道支原体感染及耐药状况,为临床合理用药提供依据。方法采用支原体培养、鉴定、药敏试剂盒对19530例泌尿生殖道感染患者的送检标本进行检测,分析支原体感染及药敏情况。结果19530例送检样本中,支原体阳性11178例,阳性率为57.24%,其中解脲支原体(Uu)、人型支原体(Mh)、Uu+Mh 混合感染阳性率分别为44.63%、0.44%和12.17%;女性支原体阳性率高于男性,差异有统计学意义(P <0.05);2008~2014年支原体阳性率呈上升趋势;支原体对交沙霉素、强力霉素、米诺环素、克拉霉素敏感率分别为88.57%、84.32%、76.09%、71.53%,对喹诺酮类抗菌药物耐药率高;Uu、Mh 和 Uu+Mh 3类感染对12种抗菌药物的耐药种数递增。结论泌尿生殖道感染以 Uu 感染为主,Mh 感染多以混合感染方式出现;交沙霉素、强力霉素是该地区治疗支原体的首选药物,临床可参考药敏结果合理用药。支原体多重耐药情况严重,应引起临床重视。  相似文献   
995.

Objective

To evaluate the utility of the quick Sepsis-related Organ Failure Assessment (qSOFA) score to predict risks for emergency department (ED) and hospital mortality among patients in a sub-Saharan Africa (SSA) setting.

Methods

This retrospective cohort study was carried out at a tertiary-care hospital, in Kigali, Rwanda and included patients ≥15 years, presenting for ED care during 2013 with an infectious disease (ID). ED and overall hospital mortality were evaluated using multivariable regression, with qSOFA scores as the primary predictor (reference: qSOFA = 0), to yield adjusted relative risks (aRR) with 95% confidence intervals (CI). Analyses were performed for the overall population and stratified by HIV status.

Results

Among 15,748 cases, 760 met inclusion (HIV infected 197). The most common diagnoses were malaria and intra-abdominal infections. Prevalence of ED and hospital mortality were 12.5% and 25.4% respectively. In the overall population, ED mortality aRR was 4.8 (95% CI 1.9–12.0) for qSOFA scores equal to 1 and 7.8 (95% CI 3.1–19.7) for qSOFA scores ≥2. The aRR for hospital mortality in the overall cohort was 2.6 (95% 1.6–4.1) for qSOFA scores equal to 1 and 3.8 (95% 2.4–6.0) for qSOFA scores ≥2. For HIV infected cases, although proportional mortality increased with greater qSOFA score, statistically significant risk differences were not identified.

Conclusion

The qSOFA score provided risk stratification for both ED and hospital mortality outcomes in the setting studied, indicating utility in sepsis care in SSA, however, further prospective study in high-burden HIV populations is needed.  相似文献   
996.

Background

Esmolol may have some potential in treating septic shock and sepsis. However, the results remain controversial. We conduct a systematic review and meta-analysis to explore the efficacy of esmolol in patients with septic shock and sepsis.

Methods

PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases are systematically searched. Randomized controlled trials (RCTs) assessing the efficacy of esmolol for septic shock and sepsis are included. Two investigators independently search articles, extract data, and assess the quality of included studies. Meta-analysis is performed using the random-effect model.

Results

Five RCTs are included in the meta-analysis. Overall, compared with control intervention in septic patients, esmolol intervention is found to significantly increase survival rate (risk ratio (RR) = 2.06; 95% confidence interval (CI) = 1.52 to 2.79; P = 0.006), decrease heart rate (Standard Mean difference (Std. MD) = ? 2.43; 95% CI = ? 4.13 to ? 0.72; P = 0.005) and TnI (Std. MD = ? 1.91; 95% CI = ? 2.39 to ? 1.43; P < 0.00001), but has no significant impact on mean arterial pressure (MAP) (Std. MD = 0.11; 95% CI = ? 0.21 to 0.44; P = 0.49), central venous pressure (CVP) (Std. MD = ? 0.11; 95% CI = ? 0.50 to 0.28; P = 0.58) and central venous oxygen saturation (ScvO2) (Std. MD = 1.87; 95% CI = ? 1.53 to 5.26; P = 0.28).

Conclusions

Esmolol treatment may be able to improve survival rate, and reduce heart rate and TnI, but has no influence on MAP, CVP and ScvO2 in patients with septic shock and sepsis.  相似文献   
997.

Objective

The aim of our study was to investigate the correlation between serum carbohydrate antigen 153 (CA153) and renal function in patients with type 2 diabetes mellitus (T2DM).

Methods

A total of 184 patients with T2DM were included, and renal function was assessed by the modification of diet in renal disease (MDRD) formula adjusted coefficient of the Chinese people.

Results

Serum CA153 concentrations were positively correlated with blood glucose (BG) and glycated hemoglobin (HbA1c) (r = .204, P = .005; r = .165, P = .025) in patients with T2DM. There was a negative correlation between serum CA153 and estimated glomerular filtration rate (GFR) (r = −.229, P = .002) in whole patients with T2DM; similarly, the correlations were observed in both women and men (r = −.228, P = .028 for women, r = −.231, P = .028 for men). Multiple linear regression analysis suggested that serum CA153 was still significantly correlated with estimated GFR (beta = −0.286, < .001).

Conclusions

Serum CA153 is negatively correlated with estimated GFR in patients with T2DM, and serum CA153 may be a potentially useful clinical biomarker to assess renal function in the study population.
  相似文献   
998.
999.

Purpose:

To measure the effects associated with sequential implementation of electronic medication storage and inventory systems and product verification devices on pharmacy technical accuracy and rates of potential medication dispensing errors in an academic medical center.

Methods:

During four 28-day periods of observation, pharmacists recorded all technical errors identified at the final visual check of pharmaceuticals prior to dispensing. Technical filling errors involving deviations from order-specific selection of product, dosage form, strength, or quantity were documented when dispensing medications using (a) a conventional unit dose (UD) drug distribution system, (b) an electronic storage and inventory system utilizing automated dispensing cabinets (ADCs) within the pharmacy, (c) ADCs combined with barcode (BC) verification, and (d) ADCs and BC verification utilized with changes in product labeling and individualized personnel training in systems application.

Results:

Using a conventional UD system, the overall incidence of technical error was 0.157% (24/15,271). Following implementation of ADCs, the comparative overall incidence of technical error was 0.135% (10/7,379; P = .841). Following implementation of BC scanning, the comparative overall incidence of technical error was 0.137% (27/19,708; P = .729). Subsequent changes in product labeling and intensified staff training in the use of BC systems was associated with a decrease in the rate of technical error to 0.050% (13/26,200; P = .002).

Conclusions:

Pharmacy ADCs and BC systems provide complementary effects that improve technical accuracy and reduce the incidence of potential medication dispensing errors if this technology is used with comprehensive personnel training.  相似文献   
1000.

Aims

Ketamine analgesia is limited by low intrinsic efficacy compounded by large interindividual variability in drug responses, possibly due to the heterogeneity in drug concentration. The CYP2B6*6 allele is associated with substantially reduced ketamine metabolism in vitro and, therefore, may affect ketamine clearance. Our aims were to examine the impact of the CYP2B6*6 allele on ketamine plasma clearance and on adverse effects in chronic pain patients.

Methods

CYP2B6 genotypes were identified in 49 chronic pain patients who received 24 h continuous subcutaneous infusions of ketamine. Steady-state plasma concentrations of ketamine (Css,k) and norketamine (Css,nk) were determined using HPLC.

Results

The median plasma clearance of ketamine after 100 mg 24 h–1 dose was significantly lower in patients with the CYP2B6*6/*6 (21.6 l h–1) and CYP2B6*1/*6 (40.6 l h–1) genotypes compared with patients with the CYP2B6*1/*1 genotype (68.1 l h–1, P < 0.001). The ketamine : norketamine plasma metabolic ratio was significantly higher in patients with the CYP2B6*6/*6 genotype than in those with the CYP2B6*1/*6 and the CYP2B6*1/*1 genotypes (P < 0.001). Patients who experienced adverse effects had lower plasma clearance (45.6 l h-1) than those who did not (52.6 l h-1, P = 0.04). The CYP2B6*6 genotype and age, and their combined impact explained 40%, 30% and 60% of the variation in Css,k, respectively. Similar results were observed after higher doses.

Conclusions

The CYP2B6*6 allele is associated with a substantial decrease in steady-state ketamine plasma clearance in chronic pain patients. The decreased clearance and resultant higher plasma concentrations may be associated with a higher incidence of ketamine adverse effects.  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