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   15588篇
  免费   1697篇
  国内免费   399篇
耳鼻咽喉   164篇
儿科学   401篇
妇产科学   264篇
基础医学   837篇
口腔科学   153篇
临床医学   1889篇
内科学   3070篇
皮肤病学   186篇
神经病学   712篇
特种医学   457篇
外国民族医学   2篇
外科学   1937篇
综合类   2162篇
现状与发展   2篇
预防医学   1677篇
眼科学   151篇
药学   2166篇
  67篇
中国医学   744篇
肿瘤学   643篇
  2024年   82篇
  2023年   579篇
  2022年   856篇
  2021年   1445篇
  2020年   1333篇
  2019年   1128篇
  2018年   1046篇
  2017年   874篇
  2016年   743篇
  2015年   673篇
  2014年   1379篇
  2013年   1269篇
  2012年   983篇
  2011年   904篇
  2010年   666篇
  2009年   587篇
  2008年   554篇
  2007年   516篇
  2006年   423篇
  2005年   335篇
  2004年   256篇
  2003年   177篇
  2002年   149篇
  2001年   122篇
  2000年   77篇
  1999年   65篇
  1998年   63篇
  1997年   60篇
  1996年   46篇
  1995年   36篇
  1994年   28篇
  1993年   37篇
  1992年   24篇
  1991年   24篇
  1990年   20篇
  1989年   18篇
  1988年   15篇
  1987年   12篇
  1986年   9篇
  1985年   20篇
  1984年   15篇
  1983年   7篇
  1982年   9篇
  1981年   7篇
  1980年   2篇
  1978年   3篇
  1977年   3篇
  1975年   1篇
  1972年   1篇
  1971年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
BackgroundLittle is known about breakfast habits of the Latin American (LA) population to support nutritional recommendations for a balanced breakfast in this region.ObjectiveTo evaluate the nutritional composition of breakfast in the LA population and to propose recommendations for a balanced breakfast.DesignThis multicenter cross-sectional study evaluated food and nutrient intake of nationally representative samples of urban populations of 8 LA countries (Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Peru, and Venezuela) in 2014-2015.Participants/settingThe sample comprised 8714 participants from the Latin American Study of Nutrition and Health, aged 15 to 65 years, randomly recruited according to geographical location, sex, age, and socioeconomic level.Main outcome measuresTwo 24-hour recalls were used to examine dietary intake. Breakfast consumers were stratified by tertiles of Nutrient-Rich Foods Index 9.3 (NRF9.3) to assess the overall diet quality of individuals. Nutrient intake at breakfast of those in the upper tertile of NRF9.3 pooled for the 8 countries was used as a reference for the development of recommendations for LA adolescents and adults.Statistical analysesComparison of food and nutrient intake of breakfast across NRF9.3 tertiles were analyzed using the Kruskal-Wallis rank sum test.ResultsOverall breakfast was an important contributor to protein, carbohydrate, and B vitamin intakes but also to added sugar and total and saturated fat intakes relative to daily intakes. Individuals in the upper NRF9.3 tertile had higher intake of key micronutrients such as calcium and potassium at breakfast compared with other tertiles. White breads/rolls/tortillas were the most consumed food group (60%), followed by butter/margarine (40%) and coffee/tea without milk (34%-50%).ConclusionsBreakfast contributed to the daily intake of B vitamins, protein, and carbohydrates but also added sugar and total and saturated fat intakes for all countries. The proposed recommendations support the nutrient density of existing highest-quality breakfast in the LA population while addressing concerns about nutrients to be encouraged or reduced.  相似文献   
22.

Objective

The advantage of arteriovenous fistulas (AVFs) in older patients requiring dialysis is controversial. We reviewed our vascular access experience in patients ≥70 years of age (older group) compared with younger patients.

Methods

We analyzed consecutive patients who underwent access surgery between 2013 and 2016. Primary success (PS) and primary patency (PP) data were analyzed between the older and younger groups before and after propensity score matching of the patients' characteristics and access composition. PS was defined as the achievement of access function that was amenable to two sessions of successful cannulation without early occlusion or maturation failure requiring revision. PP was defined as the time with uninterrupted patency without intervention.

Results

A total of 594 consecutive accesses were created among 563 patients, of whom 119 were allocated into each group after propensity score matching. In the whole cohort, 193 accesses (32.5%) were performed in older patients. AVFs were performed in 130 (67.4%) older patients and 293 (73.1%) younger patients. Regarding AVFs, the PS rate (83.6% in the older group vs 94.3% in the younger group; P = .001) and the overall PP at 6 and 12 months (73.1% and 57.1%, respectively, in the older group vs 86.7% and 77.7%, respectively, in the younger group; P = .009) were lower in the older group than in the younger group. However, no differences were found in the PS and PP rates for arteriovenous grafts between groups. Regarding the AVF location, the PS rate for forearm AVFs was significantly lower in the older group than in the younger group (76% vs 93%; P < .001); however, the PS rate of the upper arm was not different between the groups (94% vs 97%; P = .425). In the patients with PS, the PP rate of AVFs was similar between the two groups. In the older group with forearm AVFs, the median diameter of the radial artery was larger in the patients with PS than in the patients without PS (2.20 mm with PS vs 2.00 mm without PS; P = .008). The propensity score matching results demonstrated similar trends for the whole cohort, with lower PS (P = .042) and PP rates (P = .023) for AVF in the older group.

Conclusions

The outcomes after AVF were poorer in the older group than in the younger group, which was primarily due to unsatisfactory outcomes in patients with forearm AVFs. Thus, stricter criteria, especially regarding the radial artery diameter, should be applied for forearm AVFs in older patients, and additional research is necessary to delineate the risk factors for primary failure.  相似文献   
23.
The aim of this study was to analyse the effect of body mass index (BMI), both low and high values, on the perioperative complication rate in patients with oral squamous cell carcinoma (OSCC). The medical records of 259 patients operated between 2014 and 2017 for OSCC were reviewed. Univariate and multivariate analyses were performed. Sixty of the 259 patients developed 87 complications. Low or high BMI was not associated with the perioperative complication rate. A longer operating time and increased blood loss were associated with a higher perioperative complication rate and higher Clavien–Dindo grade. Low BMI, American Society of Anesthesiologists score 2 and 3, a longer operating time, and increased blood loss were associated with a longer hospital stay. Low BMI was associated with a longer hospital stay. Neither low nor high BMI was associated with the perioperative complication rate. A longer operating time and increased blood loss were associated with a higher perioperative complication rate and higher Clavien–Dindo grade.  相似文献   
24.
BackgroundScarce data exists regarding United States (US) national-level work productivity loss among adults with Multiple Sclerosis (MS).ObjectiveTo address this significant knowledge gap, we examined the national-level productivity loss among adults (18≤ age ≤64 years) with MS compared to propensity score matched non-MS controls.MethodsWe adopted a retrospective, cross-sectional, matched cohort study design with pooled data from alternate years (2005/2007/2009/2011/2013/2015) of the Medical Expenditure Panel Survey (MEPS). We included adults who were employed and alive during the calendar year. Clinical Classification System code of “80” was used to identify individuals with MS. We matched adults with MS to non-MS adults utilizing propensity scores generated based on age, gender, and race/ethnicity using a greedy matching algorithm (8:1-digit matching). Missed workdays measured productivity loss of MEPS respondents. We selected Negative Binomial Regression (NBR) analysis as the count data model for this study. Analyses were conducted using SAS 9.4 and STATA 15.0 and accounted for the complex survey design of MEPS to generate US national-level estimates.ResultsThe final propensity-score matched sample consisted of 104 and 312 (unweighted) adults with and without MS, respectively. US national-level mean [Standard Error (SE)] annual missed workdays among individuals with MS [8.94 (SE:1.59)] was significantly higher (p = 0.001) compared to propensity score matched non-MS controls [3.15 (SE:0.40)]. After adjusting for several factors, NBR showed an approximately two-fold higher rate of missed work days among individuals with MS compared to propensity score matched non-MS controls (Incidence Rate Ratio: 1.98, 95% Confidence Interval: 1.18–3.33). Severity of pain, marital status, region, and hypertension also negatively impacted work productivity in this sample.ConclusionsIndividuals with MS in the US experience significantly higher productivity loss compared to propensity score matched non-MS controls. Interventions (e.g., improved management of MS symptoms) are warranted to reduce productivity loss among individuals with MS.  相似文献   
25.
26.
27.
BackgroundAssessing patients’ functional outcomes following total knee arthroplasty (TKA) with traditional scoring systems is limited by their ceiling effects. Patient’s Joint Perception (PJP) question of the reconstructed joint is also of significant interest. Forgotten Joint Score (FJS) was created as a more discriminating option. The actual score constituting a “forgotten joint” has not yet been defined. The primary objective of this study is to compare the PJP and the FJS in TKA patients to determine the FJS score that corresponds to the patient’s perception of a natural joint.MethodsOne hundred TKAs were assessed at a mean of 40.6 months of follow-up using the PJP question, FJS, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Correlation between the 3 scores and their ceiling effects were analyzed.ResultsWith PJP question, 39% of the patients perceived a natural joint (FJS: 92.9; 95% confidence interval [CI], 89.4-96.4), 12% an artificial joint with no restriction (FJS: 79.5; 95% CI, 65.7-93.3), 36% an artificial joint with minor restrictions (FJS: 70.0; 95% CI, 63.2-76.9), and 13% had major restrictions (FJS: 47.3; 95% CI. 32.8-61.7). PJP has a high correlation with FJS and WOMAC (Spearman’s rho, −0.705 and −0.680, respectively). FJS and WOMAC had a significant ceiling effect with both reaching the best possible score in >15%.ConclusionPatients perceiving their TKA as a natural knee based on PJP have a FJS ≥89. PJP has a good correlation with FJS and may be a shorter, simple, and acceptable alternative.  相似文献   
28.
Ovarian cancer is the fourth most common cause of cancer-related death in women in the developed world, and one of the most heritable cancers. One of the most significant risk factors for epithelial ovarian cancer (EOC) is a family history of breast and/or ovarian cancer. Combined risk factors can be used in models to stratify risk of EOC, and aid in decisions regarding risk-reduction strategies. Germline pathogenic variants in EOC susceptibility genes including those involved in homologous recombination and mismatch repair pathways are present in approximately 22% to 25% of EOC. These genes are associated with an estimated lifetime risk of EOC of 13% to 60% for BRCA1 variants and 10% to 25% for BRCA2 variants, with lower risks associated with remaining genes. Genome-wide association studies have identified single nucleotide polymorphisms (SNPs) thought to explain an additional 6.4% of the familial risk of ovarian cancer, with 34 susceptibility loci identified to date. However, an unknown proportion of the genetic component of EOC risk remains unexplained. This review comprises an overview of individual genes and SNPs suspected to contribute to risk of EOC, and discusses use of a polygenic risk score to predict individual cancer risk more accurately.  相似文献   
29.
目的:回顾性分析芪地固肾方治疗特发性膜性肾病(IMN)的临床疗效与安全性。方法:选取2014年1月至2017年6月陕西中医药大学附属医院肾病科门诊及住院IMN患者141例,根据用药方案分为西药组(西药标准疗法)、中西药结合组(芪地固肾方+西药标准疗法)和中药组(芪地固肾方)3组各47例,观察3组患者治疗后临床疗效、复发率及不良反应等。结果:治疗6个月后,中西药结合组和西药组总有效率72.34%、68.09%高于中药组,治疗12个月时3组有效率比较差异无统计学意义,治疗18个月后中药组和中西药结合组总有效率75.76%、78.72%高于西药组。中药组和中西药结合组在治疗12个月和18个月后较西药组在提高中医证候疗效、减少中医证候积分上更具优势。中药组和中西药结合组复发率更低,3组均未出现严重不良反应。结论:芪地固肾方能提高IMN缓解率,在提高中医证候疗效、降低复发率上更具优势,远期疗效可观,值得进一步推广应用。  相似文献   
30.
目的:探讨玉液汤对2型糖尿病肥胖患者肠道菌群及脂质代谢影响。方法:选取2017年2月至2019年2月广州市中医医院收治的2型糖尿病肥胖患者106例作为研究对象,按照就诊顺序分为对照组和观察组,每组53例。2组均给予基础治疗+药物治疗,观察组再加用玉液汤治疗。观察2组治疗前、完成治疗后肠道菌群、脂质代谢、中医症状积分、血糖相关指标、体质量、腰围、体质量指数(BMI)变化并比较。结果:2组治疗前各指标比较差异无统计学意义(P>0.05),完成治疗后观察组患者的中医症状积分、FINS、HOMA-IR、HbAlc、BMI、腰围、体质量、TC、TG、LDL-C、肠杆菌、酵母菌、肠球菌、畏寒肢冷、腰膝酸软、脘腹2组患者治疗后HDL-C、双岐杆菌、乳杆菌、拟杆菌均较治疗后明显上升,且观察组高于对照组(P<0.05)。结论:玉液汤能改善2型糖尿病肥胖患者脂质代谢和临床症状,降低血糖,能调节肠道菌群紊乱,从而提高疗效。  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