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   1925篇
  免费   167篇
  国内免费   10篇
耳鼻咽喉   7篇
儿科学   94篇
妇产科学   50篇
基础医学   307篇
口腔科学   23篇
临床医学   246篇
内科学   356篇
皮肤病学   62篇
神经病学   214篇
特种医学   33篇
外科学   178篇
综合类   25篇
一般理论   2篇
预防医学   229篇
眼科学   15篇
药学   122篇
中国医学   2篇
肿瘤学   137篇
  2023年   11篇
  2022年   28篇
  2021年   42篇
  2020年   29篇
  2019年   57篇
  2018年   60篇
  2017年   47篇
  2016年   49篇
  2015年   51篇
  2014年   78篇
  2013年   114篇
  2012年   151篇
  2011年   144篇
  2010年   75篇
  2009年   65篇
  2008年   84篇
  2007年   118篇
  2006年   102篇
  2005年   98篇
  2004年   97篇
  2003年   77篇
  2002年   86篇
  2001年   16篇
  2000年   14篇
  1999年   19篇
  1998年   23篇
  1997年   19篇
  1996年   19篇
  1995年   14篇
  1994年   10篇
  1993年   18篇
  1992年   20篇
  1991年   17篇
  1990年   12篇
  1989年   8篇
  1988年   19篇
  1986年   10篇
  1985年   10篇
  1984年   15篇
  1983年   13篇
  1982年   16篇
  1981年   9篇
  1980年   15篇
  1979年   7篇
  1978年   8篇
  1975年   7篇
  1974年   6篇
  1973年   7篇
  1960年   5篇
  1937年   6篇
排序方式: 共有2102条查询结果,搜索用时 15 毫秒
961.

Background.

Cancers of unknown primary origin (CUP) constitute 3%–5% (50,000 to 70,000 cases) of all newly diagnosed cancers per year in the United States. Including cancers of uncertain primary origin, the total number increases to 12%–15% (180,000 to 220,000 cases) of all newly diagnosed cancers per year in the United States. Cancers of unknown/uncertain primary origins present major diagnostic and clinical challenges because the tumor tissue of origin is crucial for selecting optimal treatment. MicroRNAs are a family of noncoding, regulatory RNA genes involved in carcinogenesis. MicroRNAs that are highly stable in clinical samples and tissue specific serve as ideal biomarkers for cancer diagnosis. Our first-generation assay identified the tumor of origin based on 48 microRNAs measured on a quantitative real-time polymerase chain reaction platform and differentiated 25 tumor types.

Methods.

We present here the development and validation of a second-generation assay that identifies 42 tumor types using a custom microarray. A combination of a binary decision-tree and a k-nearest-neighbor classifier was developed to identify the tumor of origin based on the expression of 64 microRNAs.

Results.

Overall assay sensitivity (positive agreement), measured blindly on a validation set of 509 independent samples, was 85%. The sensitivity reached 90% for cases in which the assay reported a single answer (>80% of cases). A clinical validation study on 52 true CUP patients showed 88% concordance with the clinicopathological evaluation of the patients.

Conclusion.

The abilities of the assay to identify 42 tumor types with high accuracy and to maintain the same performance in samples from patients clinically diagnosed with CUP promise improved utility in the diagnosis of cancers of unknown/uncertain primary origins.  相似文献   
962.
963.
Purpose: To determine the common sources of information regarding the effects of smoking on health and their relationship to knowledge, attitudes, and preventative efforts regarding exposure to environmental tobacco smoke (ETS) among urban African-American children and adolescents.

Methods: All students who were enrolled in Grades 5–12 in an urban public school district located in the greater metropolitan area of Detroit, Michigan were surveyed using a structured, written questionnaire that assessed sources of information on the health effects of smoking, as well as knowledge, attitudes, and preventive efforts with respect to exposure to ETS. The primary analytic procedures utilized in the study were correlation analysis and analysis of variance.

Results: The African-American students surveyed in this study received information regarding the health effects of smoking from many sources, most notably television, family, and teachers. Second, students who received information on the effects of smoking on health from family and external sources (teacher, parent’s friend, and religious leader) had higher overall knowledge, attitude, and preventive efforts scores than students who received information from other sources (friends, electronic media, and printed media). Finally, family influence was greater when parents were not smokers, and influenced elementary students more than middle school or high school students.

Conclusions: The active involvement of teachers, religious leaders, parents, and other influential adults should be elicited in tobacco education and prevention efforts to maximize their effectiveness.  相似文献   

964.
Monitoring cytogenetic damage is frequently used to assess population exposure to environmental mutagens. The cytokinesis‐block micronucleus assay is one of the most widely used methods employed in these studies. In the present study we used this assay to assess the baseline frequency of micronuclei in a healthy population of father‐pregnant woman‐newborn trios drawn from two Madrid areas. We also investigated the association between micronucleus frequency and specific socioeconomic, environmental, and demographic factors collected by questionnaire. Mercury, arsenic, lead, and cadmium blood levels were measured by atomic absorption spectrometry. The association between micronucleated cell frequency and the variables collected by questionnaire, as well as, the risk associated with the presence of elevated levels of metals in blood, was estimated using Poisson models, taking the number of micronucleated cells in 1,000 binucleated cells (MNBCs) as the dependent variable. Separate analyses were conducted for the 110 newborns, 136 pregnant women, and 134 fathers in whom micronuclei could be assessed. The mean number of micronucleated cells per 1,000 binucleated cells was 3.9, 6.5, and 6.1 respectively. Our results show a statistically significant correlation in MNBC frequency between fathers and mothers, and between parents and newborns. Elevated blood mercury levels in fathers were associated with significantly higher MNBC frequency, compared with fathers who had normal mercury levels (RR:1.21; 95%CI:1.02–1.43). This last result suggests the need to implement greater control over populations which, by reason of their occupation or life style, are among those most exposed to this metal. Environ. Mol. Mutagen., 2010. © 2009 Wiley‐Liss, Inc.  相似文献   
965.
966.

Introduction

In offending populations, prevalence rates of mental disorders are much higher than in the general population. Nevertheless, it is unclear whether mental disorders can improve the prediction of recidivism beyond actuarial risk assessment tools.

Methods

The present prospective-longitudinal study was conducted between 2001 and 2021 and included 1066 men convicted of sexual offenses in Austria. All participants were evaluated with actuarial risk assessment tools for the prediction of sexual and violent recidivism and the Structured Clinical Interview for Axis I and Axis II disorders. Sexual and violent reconvictions were assessed.

Results

Exhibitionism and an exclusive pedophilia showed the strongest correlations with sexual recidivism in the total sample. In the child related offense subsample additionally a narcissistic personality disorder was correlated with sexual recidivism. The strongest correlation with violent recidivism was found for an antisocial and borderline personality disorder. None of the mental disorders could improve the prediction of recidivism beyond actuarial risk assessment tools.

Conclusion

Common current actuarial risk assessment tools revealed good predictive accuracy in men convicted of sexual offenses. With few exceptions mental disorders were only weakly associated with recidivism, suggesting that there is no direct link between mental disorders and violent and sexual reoffending. Mental disorders should nevertheless be considered in treatment issues.  相似文献   
967.

Background

Selective photothermolysis on sebaceous glands is an effective method for treating acne vulgaris (AV); however, safety, efficacy, and discomfort hinder its utilization in clinical settings.

Aims

The primary objective is to evaluate the safety and efficacy of a novel 1726 nm laser with contact cooling to treat AV.

Methods

Seventeen patients aged 18 to 36 were enrolled and treated in this IRB-approved, single-center, open-label study. Patients received up to three facial laser sessions up to seven weeks apart. Follow-up visits happened ten days post-session and at the 4 and 12 weeks following the final session. The investigator assessed the severity of device-related adverse events (AEs). Investigator Global Assessment (IGA) and inflammatory lesion counts (ILC) were used as metrics to evaluate acne resolution and skin condition enhancement. Patients' perspectives on satisfaction and comfort using this technology were assessed using Subject Experience Questionnaires (SEQ).

Results

Safety assessment showed mild and transient AEs. All subjects tolerated anesthetics-free treatments well, with a mean treatment discomfort score of 4.9 ± 1.5. Compared to baseline, a statistically significant reduction in ILC (p = 0.003) of 52% to 56% is achieved four to twelve weeks following treatment. Long-term follow-ups showed progressive improvement 24 months post-treatment with a 97% reduction in ILC. SEQs revealed high subject satisfaction (71%) with psychosocial improvement three months post-treatment.

Conclusion

The novel 1726 nm laser appears safe and effective for treating mild-to-severe acne. Acne resolution is apparent within the first month and progresses beyond the study duration.  相似文献   
968.
This ENETS guidance paper, developed by a multidisciplinary working group, provides up-to-date and practical advice on the diagnosis and management of digestive neuroendocrine carcinoma, based on recent developments and study results. These recommendations aim to pave the road for more standardized care for our patients resulting in improved outcomes. Prognosis is generally poor for digestive NEC, most are advanced at diagnosis and median survival in metastatic disease is 11–12 months. Surgery can be of benefit for localized disease after extensive preoperative imaging. Carboplatin in combination with etoposide is recommended as first-line treatment for metastatic disease. Irinotecan with fluoropyrimidines has the best evidence as second-line treatment. Immunotherapy plays a minor role in biomarker-unselected patients. Molecular profiling if available is encouraged to identify new targets. More prospective clinical trials are highly needed to fulfil the unmet needs in this field, especially on new predictive and prognostic biomarkers and to improve survival of patients with advanced disease.  相似文献   
969.
970.
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