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   8000篇
  免费   663篇
  国内免费   14篇
耳鼻咽喉   62篇
儿科学   376篇
妇产科学   196篇
基础医学   1097篇
口腔科学   34篇
临床医学   969篇
内科学   1500篇
皮肤病学   156篇
神经病学   890篇
特种医学   114篇
外科学   925篇
综合类   62篇
一般理论   12篇
预防医学   1224篇
眼科学   57篇
药学   517篇
中国医学   6篇
肿瘤学   480篇
  2024年   24篇
  2023年   170篇
  2022年   227篇
  2021年   503篇
  2020年   307篇
  2019年   462篇
  2018年   476篇
  2017年   346篇
  2016年   325篇
  2015年   306篇
  2014年   457篇
  2013年   506篇
  2012年   813篇
  2011年   763篇
  2010年   321篇
  2009年   248篇
  2008年   503篇
  2007年   412篇
  2006年   353篇
  2005年   316篇
  2004年   268篇
  2003年   214篇
  2002年   197篇
  2001年   16篇
  2000年   5篇
  1999年   15篇
  1998年   25篇
  1997年   16篇
  1996年   14篇
  1995年   9篇
  1994年   9篇
  1993年   4篇
  1992年   4篇
  1991年   2篇
  1990年   4篇
  1988年   1篇
  1987年   8篇
  1986年   8篇
  1984年   1篇
  1983年   3篇
  1981年   4篇
  1980年   1篇
  1978年   2篇
  1976年   1篇
  1975年   1篇
  1974年   2篇
  1972年   1篇
  1968年   1篇
  1961年   1篇
  1949年   1篇
排序方式: 共有8677条查询结果,搜索用时 15 毫秒
91.
The development of artificial intelligence (AI) has increased dramatically in the last 20 years, with clinical applications progressively being explored for most of the medical specialties. The field of gastroenterology and hepatology, substantially reliant on vast amounts of imaging studies, is not an exception. The clinical applications of AI systems in this field include the identification of premalignant or malignant lesions (e.g., identification of dysplasia or esophageal adenocarcinoma in Barrett’s esophagus, pancreatic malignancies), detection of lesions (e.g., polyp identification and classification, small-bowel bleeding lesion on capsule endoscopy, pancreatic cystic lesions), development of objective scoring systems for risk stratification, predicting disease prognosis or treatment response [e.g., determining survival in patients post-resection of hepatocellular carcinoma), determining which patients with inflammatory bowel disease (IBD) will benefit from biologic therapy], or evaluation of metrics such as bowel preparation score or quality of endoscopic examination. The objective of this comprehensive review is to analyze the available AI-related studies pertaining to the entirety of the gastrointestinal tract, including the upper, middle and lower tracts; IBD; the hepatobiliary system; and the pancreas, discussing the findings and clinical applications, as well as outlining the current limitations and future directions in this field.  相似文献   
92.
93.
Specific subsets of the adult population are at an increased risk of problem gambling behaviors. Previous research among these subsets has found increased rates of disordered gambling among those with drug use, alcohol use, mood, anxiety, and personality disorders. To what extent this may apply to the HIV population, known to have a high burden of co-occurring substance use and mental disorders, is not known The current study also examined the effectiveness of The Brief Biosocial Gambling Screen (BBGS) for the diagnosis of gambling disorder.

This study examined the prevalence of gambling behaviors and disordered gambling in patients enrolled in an urban HIV clinic. 100 people living with HIV (PLWH) were assessed on gambling behaviors, impulsivity, and criterion on disordered gambling. Screening for gambling disorder using the BBGS was compared to the American Psychiatric Association DSM-5 criterion.

The mean age was 53, 44% were female, 60% completed high school or above, and 80% self-identified as unemployed/disabled. 13% met four or more criteria for gambling disorder according to DSM-5 criteria. Participants that met criteria were more likely to report marijuana (p?=?.044) and heroin (p?=?.002) use, and greater impulsivity (p?<?0.00001) when compared to participants who did not meet criteria. The BBGS was able to effectively screen individuals for disordered gambling with a sensitivity of 100%, specificity of 90.8%, positive predictive value of 56.2%, and a negative predictive value of 100%.

These results suggest that urban HIV clinics may need to consider actively screening for gambling disorders, and referring to appropriate counseling and treatment for those who screen positive.  相似文献   

94.
Immunological memory is a hallmark of adaptive immunity, and understanding T cell memory will be central to the development of effective cell-mediated vaccines. The characteristics and functions of CD4 memory cells have not been well defined. Here we demonstrate that the increased size of the secondary response is solely a consequence of the increased antigen-specific precursor frequency within the memory pool. Memory cells proliferated less than primary responding cells, even within the same host. By analyzing the entry of primary and memory cells into the cell cycle, we found that the two populations proliferated similarly until day 5; after this time, fewer of the reactivated memory cells proliferated. At this time, fewer of the reactivated memory cells made IL-2 than primary responding cells, but more made IFNγ. Both these factors affected the low proliferation of the memory cells, because either exogenous IL-2 or inhibition of IFNγ increased the proliferation of the memory cells.  相似文献   
95.
This study examines the relationship between fibrillar beta-amyloid (Aβ) deposition and reduced glucose metabolism, a proxy for neuronal dysfunction, in cognitively normal (NL) individuals with a parent affected by late-onset Alzheimer's disease (AD). Forty-seven 40–80-year-old NL received positron emission tomography (PET) with 11C-Pittsburgh compound B (PiB) and 18F-fluoro-2-deoxy-d-glucose (FDG). These included 19 NL with a maternal history (MH), 12 NL with a paternal history (PH), and 16 NL with negative family history of AD (NH). Automated regions of interest, statistical parametric mapping, voxel-wise intermodality correlations, and logistic regressions were used to examine cerebral-to-cerebellar PiB and FDG standardized uptake value ratios across groups. The MH group showed higher PiB retention and lower metabolism in AD regions compared with NH and PH, which were negatively correlated in posterior cingulate, frontal, and parieto-temporal regions (Pearson r ≤ −0.57, p ≤ 0.05). No correlations were observed in NH and PH. The combination of Aβ deposition and metabolism yielded accuracy ≥ 69% for MH vs. NH and ≥ 71% for MH vs. PH, with relative risk = 1.9–5.1 (p values < 0.005). NL individuals with AD-affected mothers show co-occurring Aβ increases and hypometabolism in AD-vulnerable regions, suggesting an increased risk for AD.  相似文献   
96.
Journal of Autism and Developmental Disorders - Using data from 266 age- and sex-matched pairs of Jamaican children with autism spectrum disorder (ASD) and typically developing (TD) controls...  相似文献   
97.
98.
BackgroundUsing novel data mining methods such as natural language processing (NLP) on electronic health records (EHRs) for screening and detecting individuals at risk for psychosis. MethodThe study included all patients receiving a first index diagnosis of nonorganic and nonpsychotic mental disorder within the South London and Maudsley (SLaM) NHS Foundation Trust between January 1, 2008, and July 28, 2018. Least Absolute Shrinkage and Selection Operator (LASSO)-regularized Cox regression was used to refine and externally validate a refined version of a five-item individualized, transdiagnostic, clinically based risk calculator previously developed (Harrell’s C = 0.79) and piloted for implementation. The refined version included 14 additional NLP-predictors: tearfulness, poor appetite, weight loss, insomnia, cannabis, cocaine, guilt, irritability, delusions, hopelessness, disturbed sleep, poor insight, agitation, and paranoia. ResultsA total of 92 151 patients with a first index diagnosis of nonorganic and nonpsychotic mental disorder within the SLaM Trust were included in the derivation (n = 28 297) or external validation (n = 63 854) data sets. Mean age was 33.6 years, 50.7% were women, and 67.0% were of white race/ethnicity. Mean follow-up was 1590 days. The overall 6-year risk of psychosis in secondary mental health care was 3.4 (95% CI, 3.3–3.6). External validation indicated strong performance on unseen data (Harrell’s C 0.85, 95% CI 0.84–0.86), an increase of 0.06 from the original model. ConclusionsUsing NLP on EHRs can considerably enhance the prognostic accuracy of psychosis risk calculators. This can help identify patients at risk of psychosis who require assessment and specialized care, facilitating earlier detection and potentially improving patient outcomes.  相似文献   
99.
100.
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