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   304196篇
  免费   21622篇
  国内免费   1343篇
耳鼻咽喉   3438篇
儿科学   7834篇
妇产科学   5590篇
基础医学   39535篇
口腔科学   5467篇
临床医学   30449篇
内科学   64202篇
皮肤病学   4063篇
神经病学   29341篇
特种医学   10117篇
外国民族医学   15篇
外科学   47255篇
综合类   4217篇
现状与发展   1篇
一般理论   383篇
预防医学   26182篇
眼科学   7669篇
药学   20159篇
  6篇
中国医学   417篇
肿瘤学   20821篇
  2023年   1544篇
  2022年   2783篇
  2021年   6338篇
  2020年   3771篇
  2019年   6129篇
  2018年   6994篇
  2017年   5191篇
  2016年   5740篇
  2015年   6721篇
  2014年   10065篇
  2013年   14015篇
  2012年   21171篇
  2011年   22356篇
  2010年   12527篇
  2009年   11236篇
  2008年   19755篇
  2007年   20721篇
  2006年   20529篇
  2005年   20612篇
  2004年   19481篇
  2003年   18053篇
  2002年   16990篇
  2001年   2541篇
  2000年   1932篇
  1999年   2837篇
  1998年   3737篇
  1997年   3132篇
  1996年   2703篇
  1995年   2586篇
  1994年   2189篇
  1993年   1974篇
  1992年   1591篇
  1991年   1495篇
  1990年   1283篇
  1989年   1253篇
  1988年   1233篇
  1987年   1200篇
  1986年   1191篇
  1985年   1242篇
  1984年   1660篇
  1983年   1499篇
  1982年   1842篇
  1981年   1784篇
  1980年   1610篇
  1979年   945篇
  1978年   1017篇
  1977年   901篇
  1976年   791篇
  1975年   675篇
  1974年   691篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Brain metastases are a major cause of melanoma-related mortality and morbidity. We undertook whole-exome sequencing of 50 tumours from patients undergoing surgical resection of brain metastases presenting as the first site of visceral disease spread and validated our findings in an independent dataset of 18 patients. Brain metastases had a similar driver mutational landscape to cutaneous melanomas in TCGA. However, KRAS was the most significantly enriched driver gene, with 4/50 (8%) of brain metastases harbouring non-synonymous mutations. Hotspot KRAS mutations were mutually exclusive from BRAFV600, NRAS and HRAS mutations and were associated with a reduced overall survival from the resection of brain metastases (HR 10.01, p = 0.001). Mutations in KRAS were clonal and concordant with extracranial disease, suggesting that these mutations are likely present within the primary. Our analyses suggest that KRAS mutations could help identify patients with primary melanoma at higher risk of brain metastases who may benefit from more intensive, protracted surveillance.Subject terms: CNS cancer, Metastasis, Melanoma, Tumour biomarkers, Cancer  相似文献   
12.
Cascade testing is the process of offering genetic counseling and testing to at-risk relatives of an individual who has been diagnosed with a genetic condition. It is critical for increasing the identification rates of individuals with these conditions and the uptake of appropriate preventive health services. The process of cascade testing is highly varied in clinical practice, and a comprehensive understanding of factors that hinder or enhance its implementation is necessary to improve this process. We conducted a systematic review to identify barriers and facilitators for cascade testing and searched PubMed, CINAHL via EBSCO, Web of Science, EMBASE, and the Cochrane Library for articles published from the databases’ inception to November 2018. Thirty articles met inclusion criteria. Barriers and facilitators identified from these studies at the individual-level were organized into the following categories: (1) demographics, (2) knowledge, (3) attitudes, beliefs, and emotional responses of the individual, and (4) perceptions of relatives, relatives’ responses, and attitudes toward relatives. At the interpersonal-level, barriers and facilitators were categorized as (1) family communication-, support- and dynamics-, and (2) provider-factors. Finally, barriers at the environmental-level relating to accessibility of genetic services were also identified. Our findings suggest that several individual, interpersonal and environmental factors may play a role in cascade testing. Future studies to further investigate these barriers and facilitators are needed to inform future interventions for improving the implementation of cascade testing for genetic conditions in clinical practice.Subject terms: Preventive medicine, Genetic services  相似文献   
13.
ABSTRACT

Bellicose metaphors for cancer are ubiquitous. But are they good metaphors for health communicators to use? Because metaphors can guide reasoning about abstract concepts, framing cancer with metaphors of battle, war, and enemies leads people to apply attributes of these concepts to cancer. The current research investigates how this affects inferences about cancer treatment, prevention, and monitoring. Battles and war are usually seen as being difficult. Indeed, reading about a person’s “battle” or “fight” against cancer makes cancer treatment seem more difficult (studies 1–4). One way to approach a battle is to surrender and give up control. Consistent with this implication, battle metaphors increase fatalistic beliefs about cancer prevention (e.g. believing that there is little one can do to prevent getting cancer; study 3). Finally, even though battles invoke vigilance and action, Study 4 failed to find that such metaphors motivate people to immediately see their doctor when imagining a cancer scare. These findings suggest that bellicose metaphors for cancer can influence the health beliefs of nonpatients in ways that may make them less willing to enact healthy behaviors  相似文献   
14.
There has been a sharp rise of reported handheld laser-induced maculopathy (HLIM) cases over the past decade, a concerning trend that may continue due to unregulated online access to high power lasers. Though HLIM has distinct clinical features, not uncommonly it may masquerade as other retinal disorders. It is critical therefore to recognise the clinical and multimodal imaging characteristics of this important and potentially devastating condition. As HLIM patients are typically young, unique issues need to be considered, such as delayed presentation, difficult history, poor compliance and behavioural or psychiatric comorbidity. This article will review the clinical and diagnostic features of laser injury, with a special emphasis on the multimodal retinal findings. In addition, we present a unique case of HLIM, resembling the presentation of a placoid disease variant and illustrating choroidal ischaemia using advanced retinal imaging, that offers further insight into the mechanisms of laser injury and its complications. The issues addressed in this review aim to increase recognition of an increasingly important and trending condition with potentially profound visual complications.Subject terms: Retinal diseases, Paediatrics, Trauma  相似文献   
15.
Purpose

Prolonged mechanical ventilation (MV) is a major complication following cardiac surgery. We conducted a secondary analysis of the Transfusion Requirements in Cardiac Surgery (TRICTS) III trial to describe MV duration, identify factors associated with prolonged MV, and examine associations of prolonged MV with mortality and complications.

Methods

Four thousand, eight hundred and nine participants undergoing cardiac surgery at 71 hospitals worldwide were included. Prolonged MV was defined based on the Society of Thoracic Surgeons definition as MV lasting 24 hr or longer. Adjusted associations of patient and surgical factors with prolonged MV were examined using multivariable logistic regression. Associations of prolonged MV with complications were assessed using odds ratios, and adjusted associations between prolonged MV and mortality were evaluated using multinomial regression. Associations of shorter durations of MV with survival and complications were explored.

Results

Prolonged MV occurred in 15% (725/4,809) of participants. Prolonged MV was associated with surgical factors indicative of complexity, such as previous cardiac surgery, cardiopulmonary bypass duration, and separation attempts; and patient factors such as critical preoperative state, left ventricular impairment, renal failure, and pulmonary hypertension. Prolonged MV was associated with perioperative but not long-term complications. After risk adjustment, prolonged MV was associated with perioperative mortality; its association with long-term mortality among survivors was weaker. Shorter durations of MV were not associated with increased risk of mortality or complications.

Conclusion

In this substudy of the TRICS III trial, prolonged MV was common after cardiac surgery and was associated with patient and surgical risk factors. Although prolonged MV showed strong associations with perioperative complications and mortality, it was not associated with long-term complications and had weaker association with long-term mortality among survivors.

Study registration

www.ClinicalTrials.gov (NCT02042898); registered 23 January 2014. This is a substudy of the Transfusion Requirements in Cardiac Surgery (TRICS) III trial.

  相似文献   
16.
ABSTRACT

Purpose: To evaluate immunoblot (IB) and polymerase chain reaction (PCR) to diagnose ocular- and neurosyphilis.

Methods: Prospective cross-sectional study. Aqueous humor (AH) and cerebrospinal fluid (CSF) samples were tested for treponemal DNA or antibodies to treponemal antigens.

Results: Thirteen of 106 cases had positive syphilis serology of which 69.2% were HIV+ (median CD4+ = 181 cells/µL). Four cases met CDC criteria for neurosyphilis (3 confirmed, 1 probable) and 2 additional cases required neurosyphilis treatment according to UpToDate algorithms. All AH and CSF samples tested PCR negative. Five cases were CSF IB+ and 3 cases AH IB+. Using our classification, eight patients had confirmed neurosyphilis, one had probable neurosyphilis, three had confirmed ocular syphilis and nine had probable ocular syphilis.

Conclusion: Our findings suggest that IB of AH and CSF provides additional evidence to diagnose ocular and neurosyphilis and allows us to classify them as probable or confirmed.  相似文献   
17.
18.
19.
20.
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