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   6847篇
  免费   575篇
  国内免费   166篇
耳鼻咽喉   101篇
儿科学   243篇
妇产科学   243篇
基础医学   595篇
口腔科学   39篇
临床医学   659篇
内科学   1370篇
皮肤病学   49篇
神经病学   355篇
特种医学   238篇
外科学   551篇
综合类   521篇
预防医学   1100篇
眼科学   71篇
药学   585篇
  2篇
中国医学   38篇
肿瘤学   828篇
  2024年   6篇
  2023年   143篇
  2022年   311篇
  2021年   418篇
  2020年   312篇
  2019年   320篇
  2018年   354篇
  2017年   287篇
  2016年   244篇
  2015年   297篇
  2014年   537篇
  2013年   630篇
  2012年   401篇
  2011年   493篇
  2010年   326篇
  2009年   333篇
  2008年   343篇
  2007年   290篇
  2006年   260篇
  2005年   178篇
  2004年   156篇
  2003年   115篇
  2002年   88篇
  2001年   80篇
  2000年   60篇
  1999年   50篇
  1998年   49篇
  1997年   45篇
  1996年   42篇
  1995年   48篇
  1994年   44篇
  1993年   28篇
  1992年   35篇
  1991年   28篇
  1990年   24篇
  1989年   26篇
  1988年   26篇
  1987年   15篇
  1986年   13篇
  1985年   23篇
  1984年   22篇
  1983年   10篇
  1982年   16篇
  1981年   17篇
  1980年   8篇
  1979年   6篇
  1978年   7篇
  1977年   4篇
  1971年   6篇
  1970年   3篇
排序方式: 共有7588条查询结果,搜索用时 15 毫秒
51.
目的:探讨结直肠癌中hMLHl和hMSH2蛋白的表达的临床意义。方法:对山东省沂南县人民医院2007年2月-2010年2月间符合中国人HNPCC诊断标准的15例结直肠癌患者及同时期40例散发性结直肠癌患者的结直肠癌组织标本进行hMLH1和hMSH2蛋白检测,并对其临床病理资料进行回顾性分析。结果:15例HNPCC患者发病年龄〈50岁的4人。在结直肠癌发生的部位上,10发生在右半结肠,5例发生在左半结肠。病理类型上管状腺癌3例、黏液腺癌7例、混合癌5例。分化程度上高分化3例、中分化4例、低分化癌8例。HNPCC组中hMLH1/hMSH2蛋白阴性表达共9例,其中有8例癌灶位于右半结肠,7例病理为低分化。散发组中hMLH1/hMSH2蛋白阴性表达共6例。尚未发现hMLH1和hMSH2两种蛋白在同一病例中均为阴性表达者。结论:hMLH1和hMSH2的阴性表达与癌灶部位与病理分化高度相关;可作为HNPCC的临床初步筛查指标之一。  相似文献   
52.
3H-胸苷酸掺入法对选择前列腺癌化疗方案的价值   总被引:1,自引:0,他引:1  
目的为临床选择激素难治性前列腺癌(HRPC)的化疗方案提供参考.方法采用3H-胸苷酸(3H-TdR)掺入法检测了20例HRPC细胞对常用化疗药物的敏感性.结果HRPC对单药的体外敏感性依次为足叶乙苷(VP16)>阿霉素(ADM)、5-氟尿嘧啶(5-FU)、雌二醇氮芥(EMP)>长春花碱(VLB)>顺铂(DDP);二药联合可使敏感性进一步提高,依次为EMP加VP1 6、5-FU加ADM>EMP加VLB>5-FU加DDP三药联用抑瘤作用更强,EMP加VLB加APM、5 FU加ADM加DDP>EMP加VLB加DDP.结论3H-TdR掺入法有助于化疗方案的选择,对HRPC以联合化疗效果较好.  相似文献   
53.
Understanding reasons for the neglect of foot screening during the annual review of people with diabetes enables the development of solutions for this omission. This study explores the reasons within the context of health care delivery systems in terms of the professional, social, political and economic aspects of this screening. Information was obtained through reviewing publications on diabetic foot and health care reform. The omission of annual foot examination for people with diabetes is attributed to the nature of diabetes-related foot problems, people with diabetes, health care professionals and the current structure of health care delivery systems. Increasing the adherence to foot screening for those with diabetes requires short- and long-term strategies. Short- and long-term strategies for reminding patients and staff about foot screening are suggested.  相似文献   
54.

Objective

The benefits of prostate-specific antigen (PSA)–based prostate cancer screening are controversial. We sought to determine the change in prostate cancer presentation coinciding with the release of the United States Preventative Services Task Force recommendations against screening in a high-volume community-based urology practice.

Methods

Characteristics of men presenting for an elevated PSA at a community urology practice from August 2011 to August 2015 were queried from a prospectively collected database. A retrospective analysis of presenting PSA, Gleason grade at biopsy, and prostatectomy as well as clinical and pathologic stage was performed. Kruskal-Wallis rank sum and chi-square tests were used for analysis.

Results

Referrals for elevated PSA decreased from 933 in year 1 to 816 by year 4 (12.5% decrease) with a concomitant reduction in biopsies performed in newly referred men from 461 to 356 (22.8% decrease, P = 0.02). The proportion of men presenting with PSAs>10 increased from 28.1% to 36.8% (P = 0.009). First-time biopsy-positivity rate increased from 48.4% to 62.4% with a rise in the proportion having Gleason≥7 from 51.6% to 69.7% (P = 0.0001). Of the 578 men who underwent radical prostatectomy, there was a 19.4% increase in Gleason≥7 tumors (P = 0.01).

Conclusions

Our findings demonstrate a decrease in elevated PSA referrals, increase in PSA at the time of referral, decrease in detection of low-risk disease, and increase in detection of intermediate-/high-risk disease in a high-volume, multisite, community-based urology practice, coinciding with the United States Preventative Services Task Force recommendations against PSA screening.  相似文献   
55.
PurposeThe majority of patients with an anorectal malformation (ARM) have associated congenital anomalies. It is well established that all patients diagnosed with an ARM should undergo systematic screening, including renal, spinal, and cardiac imaging. This study aimed to evaluate the findings and completeness of screening, following local implementation of standardized protocols.MethodsA retrospective cohort study was performed assessing all patients with an ARM managed at our tertiary pediatric surgical center, following a standardized protocol implementation for VACTERL screening (January 2016–December 2021). Cohort demographics, medical characteristics, and screening investigations were analyzed. Findings were compared with our previously published data (2000–2015), conducted prior to protocol implementation.ResultsOne hundred twenty-seven (64 male, 50.4%) children were eligible for inclusion. Complete screening was performed in 107/127 (84.3%) children. Of these, one or more associated anomalies were diagnosed in 85/107 (79.4%), whilst the VACTERL association was demonstrated in 57/107 (53.3%). The proportion of children that underwent complete screening increased significantly in comparison with those assessed prior to protocol implementation (RR 0.43 [CI 0.27–0.66]; p < 0.001). Children with less complex ARM types were significantly less likely to receive complete screening (p = 0.028). Neither presence of an associated anomaly, nor prevalence of the VACTERL association, differed significantly by ARM type complexity.ConclusionScreening for associated VACTERL anomalies in children with ARM was significantly improved following standardized protocol implementation. The prevalence of associated anomalies in our cohort supports the value of routine VACTERL screening in all children with ARM, regardless of malformation type.Level of EvidenceII.  相似文献   
56.
目的 探讨薄基底膜肾病(TBMN)合并局灶节段性肾小球硬化症(FSGS)的遗传学机制.方法 对一病理学诊断为TBMN合并FSGS患者及其家系的COL4A3和COL4A4基因突变,应用与COL4A3和COL4A4基因连锁的微卫星标记连锁分析方法进行分析.PCR扩增COIAA3和COL4A4全部98个外显子后,直接测序筛查突变.同时测序排除已为公认的FSGS相关基因NPHS1、NPHS2、WT1、TRPC6、ACTN4、CD2AP突变导致FSGS的可能.结果 微卫星标记连锁分析显示此家系与COL4A3和COL4A4基因连锁.直接测序在此家系中发现疾病患者COL4A4基因1214位的鸟嘌呤突变为腺嘌呤,导致Ⅳ型胶原α4链第405位甘氨酸突变为谷氨酸,并且发现COL4A3基因一多态性IVS1-4C>T.此多态性随疾病分布,可能与致病相关.未发现FSGS相关基因的突变.结论 此家系是在TBMN的基础上发生FSGS.Ⅳ型胶原α4链突变及随疾病分布的基因多态性是否导致TBMN合并FSGS或使其易感性增加尚待更多家系进一步研究.  相似文献   
57.
BACKGROUND: Screening mammography has led to earlier diagnosis of breast cancer; however, the increased tissue density of young women can complicate mammographic interpretation. We hypothesized that magnetic resonance imaging (MRI) has value in detection of mammographically occult breast cancers, particularly in premenopausal women for whom the sensitivity of mammography is compromised. METHODS: Data were available for 89 women with biopsy-proven breast cancer who had undergone both mammography and breast MRI. Variables evaluated included menopausal status and radiographic findings. Data were analyzed using Fisher's Exact test; P < .05 was considered significant. RESULTS: Of the 89 women in our study, 69 were perimenopausal or postmenopausal and 20 were premenopausal at the time of diagnosis. The malignant lesion was identified on mammography and MRI for a majority of patients. One third of premenopausal women had negative mammography but positive MRI findings. CONCLUSIONS: Our findings support a role for breast MRI in supplementing conventional mammography for early detection of breast cancer in premenopausal women.  相似文献   
58.

Background

Evidence indicates that an abnormal digital rectal examination (DRE) is a risk factor for high-grade prostate cancer (PC).

Objective

To determine whether men with an initially suspicious DRE, a prostate-specific antigen (PSA) level ≥3.0 ng/ml, and a benign prostate biopsy are at higher risk for significant PC at rescreening than men with an initially normal DRE, and whether an adaptation of the rescreening interval is warranted for this group.

Design, Setting, and Participants

Within the European Randomized Study of Screening for Prostate Cancer (ERSPC), Rotterdam, 2218 men underwent biopsy of the prostate (from 1993 to 2000) with a benign result at initial screening. The serum PSA was determined every 4 yr. A PSA level of ≥3.0 ng/ml prompted a DRE and a lateralised sextant biopsy.

Measurements

Number and characteristics of PCs found at repeat screenings and as interval cancers (ICs) were compared between men with or without a suspicious DRE result at initial screening. Multivariate logistic regression analyses were performed to evaluate if an initially suspicious DRE was a significant predictor for detecting cancer at consecutive screenings.

Results and Limitations

After 4 yr, the total number of PCs detected in men with and without an initially suspicious DRE was, respectively, 27 (6%) versus 103 (6%) (p = 0.99). After 8 yr these numbers increased, respectively, to,45 (10%) versus 167 (10%) (p = 0.88). The proportion of clinically significant PCs was 2% and 3%, respectively, for the group with initially normal and abnormal DRE after 8 yr. Having a suspicious DRE result at initial screening was not a significant predictor for detecting PC after 4 yr [odds ratio (OR) = 1.15, p = 0.59) or 8 yr (OR = 1.41, p = 0.43)]. A limitation of this study is the relatively short follow-up of 8 yr.

Conclusions

During a follow-up of 8 yr after initial cancer-negative biopsy, an initially suspicious DRE did not influence the chance for detection of cancer or significant cancer at later screens. An adaptation of the rescreening interval on the basis of the initial DRE-outcome is not warranted in future population-based screening for prostate cancer.  相似文献   
59.
《Injury》2016,47(9):2000-2005
BackgroundThe precise role of thoracic CT in penetrating chest trauma remains to be defined. We hypothesized that thoracic CT effectively screens hemodynamically normal patients with penetrating thoracic trauma to surgery vs. expectant management (NOM).MethodsA ten-year review of all penetrating torso cases was retrospectively analyzed from our urban University-based trauma center. We included hemodynamically normal patients (systolic blood pressure ≥90) with penetrating chest injuries that underwent screening thoracic CT. Hemodynamically unstable patients and diaphragmatic injuries were excluded. The sensitivity, specificity, positive predictive value and negative predictive value were calculated.ResultsA total of 212 patients (mean injury severity score = 24, Abbreviated Injury Score for Chest = 3.9) met inclusion criteria. Of these, 84.3% underwent NOM, 9.1% necessitated abdominal exploration, 6.6% underwent exploration for retained hemothorax/empyema, 6.6% underwent immediate thoracic exploration for significant injuries on chest CT, and 1.0% underwent delayed thoracic exploration for missed injuries. Thoracic CT had a sensitivity of 82%, specificity of 99%, positive predictive value of 90%, a negative predictive value of 99%, and an accuracy of 99% in predicting surgery vs. NOM.ConclusionsThoracic CT has a negative predictive value of 99% in triaging hemodynamically normal patients with penetrating chest trauma. Screening thoracic CT successfully excludes surgery in patients with non-significant radiologic findings.  相似文献   
60.
BACKGROUND: Obesity and metabolic syndrome are risk factors for the development of chronic kidney disease (CKD). Few studies have examined the effect of change in body mass index (DeltaBMI) on CKD incidence in a general screening setting. METHODS: Subjects of this study were screenees that participated in the screening program of the Okinawa General Health Maintenance Association in 1993 and 2003 in Okinawa, Japan. Using identification number, birth date, sex, and other recorded identifiers, we identified 33,389 subjects among the 1993 screening participants (N = 143,948) who also participated in the 2003 screening. CKD was defined as estimated glomerular filtration rate <60 ml/min/1.73 m(2), according to the modification of diet in renal disease study equation. Obesity was defined as BMI > or = 25 kg/m(2). RESULTS: CKD prevalence was 13.8% in 1993 and 22.4% in 2003. The incidence of developing CKD in 10 years was 15.5%. The effect of DeltaBMI on CKD incidence was evaluated after considering other confounding factors such as age, sex, blood pressure, BMI, fasting plasma glucose, and proteinuria. Median DeltaBMI was 1.0%. The adjusted odds ratio (95% CI) for the effect of DeltaBMI on CKD incidence was 1.111 (1.026-1.204, P < 0.01; entire study population), 1.271 (1.116-1.448, P = 0.0030; men), and 1.030 (0.931-1.139, NS; women), when DeltaBMI > or = 1% was taken as a reference. DeltaBMI was an independent predictor of CKD incidence. CONCLUSIONS: The present results suggest that there was an inverse relationship between DeltaBMI and CKD incidence among screened subjects. The reasons for this observation are not clear, but careful follow-up for DeltaBMI is necessary, particularly in obese men with proteinuria.  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