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   115127篇
  免费   10406篇
  国内免费   2070篇
耳鼻咽喉   1106篇
儿科学   2968篇
妇产科学   1917篇
基础医学   8134篇
口腔科学   2279篇
临床医学   15106篇
内科学   14600篇
皮肤病学   1740篇
神经病学   5727篇
特种医学   3086篇
外国民族医学   9篇
外科学   11660篇
综合类   18975篇
现状与发展   1篇
一般理论   12篇
预防医学   19561篇
眼科学   1242篇
药学   8146篇
  279篇
中国医学   5711篇
肿瘤学   5344篇
  2024年   365篇
  2023年   2260篇
  2022年   3455篇
  2021年   5308篇
  2020年   5188篇
  2019年   6517篇
  2018年   5918篇
  2017年   5143篇
  2016年   4258篇
  2015年   4173篇
  2014年   8082篇
  2013年   8018篇
  2012年   7154篇
  2011年   7200篇
  2010年   5717篇
  2009年   5296篇
  2008年   5204篇
  2007年   4779篇
  2006年   4247篇
  2005年   3228篇
  2004年   2648篇
  2003年   2171篇
  2002年   1703篇
  2001年   1392篇
  2000年   1133篇
  1999年   979篇
  1998年   747篇
  1997年   725篇
  1996年   576篇
  1995年   567篇
  1994年   458篇
  1993年   370篇
  1992年   307篇
  1991年   245篇
  1990年   214篇
  1989年   198篇
  1988年   164篇
  1985年   988篇
  1984年   1489篇
  1983年   1178篇
  1982年   1173篇
  1981年   1172篇
  1980年   1010篇
  1979年   890篇
  1978年   690篇
  1977年   499篇
  1976年   653篇
  1975年   574篇
  1974年   479篇
  1973年   440篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
BackgroundVoices for Food was a longitudinal community, food pantry–based intervention informed by the social ecological model, and designed to improve food security, dietary intake, and quality among clients, which was carried out in 24 rural food pantries across 6 Midwestern states.ObjectiveOur objective was to evaluate changes in adult food security, dietary intake, and quality from baseline (2014) to follow-up (2016), and to assess the role of adult food security on dietary outcomes.DesignA multistate, longitudinal, quasi-experimental intervention with matched treatment and comparison design was used to evaluate treatment vs comparison group changes over time and changes in both groups over time.Participants/settingAdult food pantry clients (n = 617) completed a demographic food security survey, and up to three 24-hour dietary recalls at baseline (n = 590) and follow-up (n = 160).InterventionCommunity coaching served as the experimental component, which only “treatment” communities received, and a food council guide and food pantry toolkit were provided to both “treatment” and matched “comparison” communities.Main outcome measuresChange in adult food security status, mean usual intakes of nutrients and food groups, and Healthy Eating Index-2010 scores were the main outcome measures.Statistical analyses performedLinear mixed models estimated changes in outcomes by intervention group and by adult food security status over time.ResultsImprovements in adult food security score (–0.7 ± 0.3; P = .01), Healthy Eating Index-2010 total score (4.2 ± 1.1; P < .0001), and empty calories component score (3.4 ± 0.5; P <.0001) from baseline to follow-up were observed in treatment and comparison groups, but no statistically significant changes were found for adult food security status, dietary quality, and usual intakes of nutrients and food groups between the 2 groups over time. The intervention effect on dietary quality and usual intake changes over time by adult food security status were also not observed.ConclusionsFood pantry clients in treatment and comparison groups had higher food security and dietary quality at the follow-up evaluation of the Voices for Food intervention trial compared with baseline, despite the lack of difference among the groups as a result of the experimental coaching component.  相似文献   
2.
PurposeAccording to the social determinants of health framework, income inequality is a potential risk factor for adverse mental health. However, few studies have explored the mechanisms suspected to mediate this relationship. The current study addresses this gap through a mediation analysis to determine if social support and community engagement act as mediators linking neighbourhood income inequality to maternal anxiety and depressive symptoms within a cohort of new mothers living in the City of Calgary, Canada.MethodsData collected at three years postpartum from mothers belonging to the All Our Families (AOF) cohort were used in the current study. Maternal data were collected between 2012 and 2015 and linked to neighbourhood socioeconomic data from the 2006 Canadian Census. Income inequality was measured using Gini coefficients derived from 2006 after-tax census data. Generalized structural equation models were used to quantify the associations between income inequality and mental health symptoms, and to assess the potential direct and indirect mediating effects of maternal social support and community engagement.ResultsIncome inequality was not significantly associated with higher depressive symptoms (β = 0.32, 95%CI = −0.067, 0.70), anxiety symptoms (β = 0.11, 95%CI = −0.39, 0.60), or lower social support. Income inequality was not associated with community engagement. For the depression models, higher social support was significantly associated with lower depressive symptoms (β = −0.13, 95%CI = −0.15, −0.097), while community engagement was not significantly associated with depressive symptoms (β = 0.059, 95%CI = −0.15, 0.27). Similarly, for the anxiety models, lower anxiety symptoms were significantly associated with higher levels of social support (β = −0.17, 95%CI = −0.20, −0.13) but not with higher levels of community engagement (β = 0.14, 95%CI = −0.14, 0.41).ConclusionThe current study did not find clear evidence for social support or community engagement mediating the relationship between neighbourhood income inequality and maternal mental health. Future investigations should employ a broader longitudinal approach to capture changes in income inequality, potential mediators, and mental health symptomatology over time.  相似文献   
3.
BackgroundThe goal of this study was to characterize contemporary performance benchmarks and risk factors associated with negative appendectomy (NA) in children with suspected appendicitis.MethodsA multicenter retrospective cohort analysis of children undergoing appendectomy for suspected appendicitis was performed using data from the 2016–2021 NSQIP-Pediatric Appendectomy Targeted Public Use Files. Multivariable regression was used to evaluate the influence of year, age, sex, and WBC count on NA rate, and to generate rate estimates for NA based on different combinations of demographic characteristics and WBC profiles.Results100,322 patients were included from 140 hospitals. The overall NA rate was 2.4%, and rates decreased significantly during the study period (2016: 3.1% vs. 2021: 2.3%, p < 0.001). In adjusted analyses, the highest risk for NA was associated with a normal WBC (<9000/mm3; OR 5.31 [95% CI: 4.87–5.80]), followed by female sex (OR 1.55 [95% CI: 1.42–1.68]) and age <5 years (OR 1.64 [95% CI 1.39, 1.94]). Model-estimated risk for NA varied significantly across demographic and WBC strata, with a 14.4-fold range in rates between subgroups with the lowest and highest predicted risk (males 13–17 years with elevated WBC [1.1%] vs. females 3–4 years with normal WBC [15.8%]).ConclusionsContemporary NA rates have decreased over time, however NA risk remains high in children without a leukocytosis, particularly for girls and children <5 years of age. These data provide contemporary performance benchmarks for NA in children with suspected appendicitis and identify high-risk populations where further efforts to mitigate NA risk should be targeted.Level of EvidenceIII.  相似文献   
4.
目的 分析不同特征的结直肠癌患者就医行为选择在中医院(含中西医结合医院)、西医院及肿瘤专科医院间的差异,为合理引导结直肠癌患者适宜就医及制订相关政策提供依据。方法 收集北京地区2018年1月-2019年12月17家三级甲等医院21894例首诊结直肠癌成年住院患者的病案首页数据,采用EmpowerStats 2.0对数据进行描述性分析。结果 21894例结直肠癌患者中就诊于中医院的有862例(3.93%),西医院的有8723例(39.85%),肿瘤专科医院的有12309例(56.22%)。对于不同医疗机构,男性占比均大于女性,58-68岁患者占比最大。且结直肠癌患者年龄、医疗付款方式及肿瘤分期在不同医疗机构间的分布存在差异(P<0.001)。西医院及肿瘤专科医院结直肠癌Ⅲ期患者占比最大,而就诊于中医院患者中结直肠癌Ⅳ期最多。从地域分布来看,异地就诊比例(57.32%)大于本地,且就诊于肿瘤专科医院的患者中73.66%来自外地。患者来源前三名分别是北京市、河北省及内蒙古自治区。而在北京市内,西医院患者主要来源于朝阳区、海淀区及西城区,中医院患者主要来源于海淀区、朝阳区及丰台区,肿瘤专科医院则主要来源于朝阳区、海淀区及丰台区。结论 应大力倡导年轻以及早期结直肠癌患者向中医院分流,充分施展中医药在结直肠癌患者中的治疗优势;发挥三级医院带动作用,建立对口帮扶医院,减少不必要的跨省流动及提倡结直肠癌的早筛早治,以降低结直肠癌死亡率。  相似文献   
5.
6.
7.
8.
9.
PurposeTo investigate the safety and efficacy of thyroid artery embolization (TAE) in the treatment of nodular goiter (NG).MethodsDuring a 5.5-year period, 56 consecutive patients with a NG underwent TAE. In Group A, there were 20 patients with a solitary/dominant 5–11-cm nodule, and in Group B, there were 36 patients with numerous nodules. Of the 56 patients, 47 (84%) had a retrosternal goiter and 25 had hyperthyroidism. In all patients, clinical and radiological evaluations were made at baseline and 6 months after TAE, and these parameters were statistically compared.ResultsIn 56 patients, 145 of the 146 thyroid arteries were successfully embolized. The 30-day mortality rate was 1.8%. Minor and major complications occurred in 25 and 2 patients, respectively. Six months after the TAE, the mean nodule volume was reduced from 80.2 mL to 25.0 mL, the mean thyroid volume was reduced from 147.0 mL to 62.6 mL, and the mean intrathoracic extension was reduced from 31.7 mm to 15.9 mm (P < .001). Of the 22 patients with non–Graves hyperthyroidism, 19 (86%) became euthyroid. The mean thyroid-related patient-reported outcome scores improved from 155.4 to 70.4 (P < .001). Of the 51 patients, 50 (98%) declared that they would recommend TAE to other patients with NG.ConclusionsTAE is safe and effective for the treatment of NG, with a significant volume reduction of the nodule(s) and thyroid gland.  相似文献   
10.
PurposeTo review and to compare indirectly the outcomes of minimally invasive therapies for the treatment of lower urinary tract symptoms secondary to benign prostatic hyperplasia.Materials and MethodsA literature search via Medline and Cochrane Central databases was completed for randomized control studies published between January 2000 to April 2020 for the following therapies: Rezum, Urolift, Aquablation, and prostatic artery embolization (PAE). Data on the following variables were included: International prostate symptom score (IPSS), maximum urinary flow rate, quality of life, and postvoid residual (PVR). Standard mean differences between treatments were compared through a meta-analysis using transurethral resection of the prostate (TURP) to assess differences in treatment effect.ResultsThere was no significant difference in outcomes between therapies for IPSS at the 3, 6, and 12-month follow ups. Although outcomes for Rezum were only available out to 3 months, there were no consistently significant differences in outcomes when comparing Aquablation versus PAE versus Rezum. TURP PVR was significantly better than Urolift at 3, 6, and 12 months. No significant differences in minor or major adverse events were noted.ConclusionAlthough significant differences in outcomes were limited, Aquablation and PAE were the most durable at 12 months. PAE has been well studied on multiple randomized control trials with minimal adverse events while Aquablation has limited high quality data and has been associated with bleeding-related complications.  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