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   10376篇
  免费   784篇
  国内免费   25篇
耳鼻咽喉   116篇
儿科学   243篇
妇产科学   159篇
基础医学   1165篇
口腔科学   267篇
临床医学   1111篇
内科学   1823篇
皮肤病学   95篇
神经病学   903篇
特种医学   390篇
外科学   1966篇
综合类   129篇
一般理论   5篇
预防医学   1043篇
眼科学   164篇
药学   894篇
中国医学   6篇
肿瘤学   706篇
  2023年   52篇
  2022年   134篇
  2021年   262篇
  2020年   160篇
  2019年   239篇
  2018年   294篇
  2017年   230篇
  2016年   237篇
  2015年   283篇
  2014年   401篇
  2013年   521篇
  2012年   828篇
  2011年   740篇
  2010年   415篇
  2009年   340篇
  2008年   571篇
  2007年   612篇
  2006年   547篇
  2005年   578篇
  2004年   520篇
  2003年   503篇
  2002年   426篇
  2001年   128篇
  2000年   116篇
  1999年   151篇
  1998年   87篇
  1997年   68篇
  1996年   65篇
  1995年   56篇
  1994年   52篇
  1993年   53篇
  1992年   82篇
  1991年   78篇
  1990年   80篇
  1989年   72篇
  1988年   68篇
  1987年   63篇
  1986年   65篇
  1985年   56篇
  1984年   81篇
  1983年   64篇
  1982年   46篇
  1981年   58篇
  1980年   43篇
  1979年   54篇
  1978年   63篇
  1977年   51篇
  1976年   58篇
  1974年   56篇
  1973年   60篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
BackgroundSelection of the optimal treatment modality for primary liver cancers remains complex, balancing patient condition, liver function, and extent of disease. In individuals with preserved liver function, liver resection remains the primary approach for treatment with curative intent but may be associated with significant mortality. The purpose of this study was to establish a simple scoring system based on Model for End-stage Liver Disease (MELD) and extent of resection to guide risk assessment for liver resections.MethodsThe 2005–2015 NSQIP database was queried for patients undergoing liver resection for primary liver malignancy. We first developed a model that incorporated the extent of resection (1 point for major hepatectomy) and a MELD-Na score category of low (MELD-Na =6, 1 point), medium (MELD-Na =7–10, 2 points) or high (MELD-Na >10, 3 points) with a score range of 1–4, called the Hepatic Resection Risk Score (HeRS). We tested the predictive value of this model on the dataset using logistic regression. We next developed an optimal multivariable model using backwards sequential selection of variables under logistic regression. We performed K-fold cross validation on both models. Receiver operating characteristics were plotted and the optimal sensitivity and specificity for each model were calculated to obtain positive and negative predictive values.ResultsA total of 4,510 patients were included. HeRS was associated with increased odds of 30-day mortality [HeRS =2: OR =3.23 (1.16–8.99), P=0.025; HeRS =3: OR =6.54 (2.39–17.90), P<0.001; HeRS =4: OR =13.69 (4.90–38.22), P<0.001]. The AUC for this model was 0.66. The AUC for the optimal multivariable model was higher at 0.76. Under K-fold cross validation, the positive predictive value (PPV) and negative predictive value (NPV) of these two models were similar at PPV =6.4% and NPV =97.7% for the HeRS only model and PPV =8.4% and NPV =98.1% for the optimal multivariable model.ConclusionsThe HeRS offers a simple heuristic for estimating 30-day mortality after resection of primary liver malignancy. More complicated models offer better performance but at the expense of being more difficult to integrate into clinical practice.  相似文献   
82.
Archives of Sexual Behavior - Gay, bisexual, and other men who have sex with men (MSM) experience alarming HIV disparities alongside sub-optimal engagement in HIV interventions. Among MSM, stigma...  相似文献   
83.
Pilkington  Bryan C. 《HEC forum》2021,33(3):233-245
HEC Forum - In this paper, I consider the role of conscience in medical practice. If the conscientious practice of individual practitioners cannot be defended or is incoherent or unreasonable on...  相似文献   
84.
85.
86.
Retroviruses emerged before Homo sapiens in the course of vertebrate evolution. The first human retrovirus was isolated in 1979; the human immunodeficiency virus (HIV-1) assumed epidemic importance in 1981. That such a novel threat to the survival of our species struck only when we had in place, for the first time, the science necessary to fight back seems remarkably coincidental. Cause-and-effect explanations include (1) human activities unique to the late 20th century and (2) a merciful, slow-to-anger God willing to "hold back" until the right time (chairos). By either possibility, AIDS might signify our failure to manage properly the world's ecosystems, the limitations of scientific progress, and/or deficiencies in our collective worldview.  相似文献   
87.
Thirty years after the world's first successful heart transplant, UK services are embroiled in a funding row. The country's eight units carried out more than 200 transplants last year, but after-care costs are rising as more people survive longer, and cardiologists fear the switch from central to regional funding will lead to cuts. Jenny Bryan looks at the past, present and future.  相似文献   
88.
Picture archiving and communication systems (PACS) are an example of the application of computer technology in the medical field. PACS automates image handling in a hospital and has the potential to transform the way radiology is currently performed. This paper focuses on the evaluation of the PACS technology, and considers the claims that have been made for PACS, how these claims might be turned into questions to be addressed by evaluation and the appropriate methods for the evaluation of PACS. A distinction is drawn between evaluation questions for which the hospital is the appropriate focus and those for which the patient is the appropriate focus. The preferred research design is different for hospital focused PACS evaluation and patient-focused evaluation of small scale PACS systems. A contemporaneous experimental comparison within hospitals is the preferred design for the patient-focused evaluation of small scale PACS systems. The patient-focused evaluation of large scale systems and the hospital-focused evaluation of all PACS systems could feasibly be conducted as contemporaneous experimental comparisons between hospitals but the large research costs implied by such a design almost certainly mean that non-contemporaneous, non-experimental comparisons within hospitals are more realistic. The current situation for the PACS technology is that it has potential, but as yet unproven, benefits and a large capital cost. Thus, the primary purpose of funding additional PACS implementations must be to add to the currently small body of evaluation evidence.  相似文献   
89.
90.
OBJECTIVES: To establish the net costs to the hospital and the broad range of benefits associated with a hospital-wide picture archiving and communication system (PACS) that comprised digital acquisition, storage and transmission of radiological images via a hospital-wide network to 150 workstations. METHODS: 'Before and after' comparisons and time series analyses at Hammersmith Hospital (London, UK), and comparison with five other British hospitals where PACS was not being installed. The cost analysis considered implementation costs and changes in key elements of hospital running costs, including the impact of changes in the length of inpatient stays. A range of benefit measures were investigated, including image availability, avoidance of repeat imaging, avoidance of exposure to radiation, patient turn-round speed, time from examination to image availability in intensive care, avoidance of diagnostic 'errors' by casualty doctors, the additional diagnostic value of PACS-based images and clinician satisfaction. RESULTS: The annual equivalent capital cost of the PACS was 1.7 million Pounds (annual equivalent replacement cost: 0.8 million Pound). Overall, the PACS substantially increased running costs. No convincing evidence of a PACS-induced change in length of inpatient stay was found. PACS was associated with some improvements in the performance of the radiology department: improved image availability (97.7% versus 86.9%), lower repeat imaging rate (7.3% versus 9.9%) and 20% lower total radiation doses for examinations of the lateral lumbar spine. No improvements were identified in the quality of the radiology reporting service. Benefits outside radiology included shorter time from examination to image availability for routine uses in intensive care (19 versus 37 minutes), and a lower rate of diagnostic 'errors' in casualty (0.65% versus 1.51%). High levels of satisfaction with PACS were found amongst both providers and clinical users. CONCLUSIONS: PACS was almost universally preferred by users and brought many operational and clinical benefits. However, these advantages came at a significant capital and net running cost.  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