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   1664453篇
  免费   140127篇
  国内免费   7635篇
耳鼻咽喉   22437篇
儿科学   53608篇
妇产科学   47372篇
基础医学   235089篇
口腔科学   48474篇
临床医学   149809篇
内科学   322297篇
皮肤病学   34978篇
神经病学   133272篇
特种医学   67600篇
外国民族医学   527篇
外科学   250808篇
综合类   50116篇
一般理论   565篇
预防医学   126654篇
眼科学   39149篇
药学   128849篇
  48篇
中国医学   7004篇
肿瘤学   93559篇
  2018年   17385篇
  2017年   14097篇
  2016年   15059篇
  2015年   18550篇
  2014年   25165篇
  2013年   35257篇
  2012年   48342篇
  2011年   51038篇
  2010年   30302篇
  2009年   28234篇
  2008年   47066篇
  2007年   49153篇
  2006年   50083篇
  2005年   48567篇
  2004年   46685篇
  2003年   44519篇
  2002年   43184篇
  2001年   77159篇
  2000年   79733篇
  1999年   67845篇
  1998年   17917篇
  1997年   16532篇
  1996年   16185篇
  1995年   16824篇
  1994年   15728篇
  1993年   14606篇
  1992年   55901篇
  1991年   54211篇
  1990年   52968篇
  1989年   51168篇
  1988年   47520篇
  1987年   46798篇
  1986年   44481篇
  1985年   43003篇
  1984年   32091篇
  1983年   27587篇
  1982年   16114篇
  1981年   14416篇
  1979年   30462篇
  1978年   21034篇
  1977年   17703篇
  1976年   16653篇
  1975年   17526篇
  1974年   21469篇
  1973年   20659篇
  1972年   18850篇
  1971年   17760篇
  1970年   16276篇
  1969年   15261篇
  1968年   13941篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Modified-release opioids are often prescribed for the management of moderate to severe acute pain following total hip and knee arthroplasty, despite recommendations against their use due to increasing concerns regarding harm. The primary objective of this multicentre study was to examine the impact of modified-release opioid use on the incidence of opioid-related adverse events compared with immediate-release opioid use, among adult inpatients following total hip or knee arthroplasty. Data for total hip and knee arthroplasty inpatients receiving an opioid analgesic for postoperative analgesia during hospitalisation were collected from electronic medical records of three tertiary metropolitan hospitals in Australia. The primary outcome was the incidence of opioid-related adverse events during hospital admission. Patients who received modified with or without immediate-release opioids were matched to those receiving immediate-release opioids only (1:1) using nearest neighbour propensity score matching with patient and clinical characteristics as covariates. This included total opioid dose received. In the matched cohorts, patients given modified-release opioids (n = 347) experienced a higher incidence of opioid-related adverse events overall, compared with those given immediate-release opioids only (20.5%, 71/347 vs. 12.7%, 44/347; difference in proportions 7.8% [95%CI 2.3–13.3%]). Modified-release opioid use was associated with an increased risk of harm when used for acute pain during hospitalisation after total hip or knee arthroplasty.  相似文献   
3.
目的比较飞秒激光制瓣准分子激光原位角膜磨镶术(FS-LASIK)、全飞秒激光小切口角膜基质透镜取出术(SMILE)和有晶状体眼后房型人工晶状体(ICL V4c)植入术三者矫正中低度近视的效果。方法采用回顾性研究。以惠州爱尔眼科医院2019年6月至2020年4月矫正中低度近视120例(120眼)作为研究对象,受术者分为FS-LASIK组、SMILE组及ICL组,每组40例(40眼),各组分别接受相应的手术,术后随访3个月比较其矫正效果。结果术后1个月及3个月,3组间视力及有效性指数对比差异无统计学意义(P>0.05);ICL组安全性指数高于SMILE组及FS-LASIK组(P<0.05)。术后3个月FS-LASIK组的三叶草像差、彗差和球差出现明显变化,而SMILE组的变化较小,ICL组变化最小(P<0.05)。结论对中低度近视FS-LASK、SMILE及ICL植入术三者均有确切疗效,而ICL V4c植入术的安全性最高,患者的视觉质量最好。  相似文献   
4.
5.
6.
Oral squamous cell carcinomas (OSCCs) develop in genetically altered epithelium in the mucosal lining, also coined as fields, which are mostly not visible but occasionally present as white oral leukoplakia (OL) lesions. We developed a noninvasive genetic assay using next-generation sequencing (NGS) on brushed cells to detect the presence of genetically altered fields, including those that are not macroscopically visible. The assay demonstrated high accuracy in OL patients when brush samples were compared with biopsies as gold standard. In a cohort of Fanconi anemia patients, detection of mutations in prospectively collected oral brushes predicted oral cancer also when visible abnormalities were absent. We further provide insight in the molecular landscape of OL with frequent changes of TP53, FAT1 and NOTCH1. NGS analysis of noninvasively collected samples offers a highly accurate method to detect genetically altered fields in the oral cavity, and predicts development of OSCC in high-risk individuals. Noninvasive genetic screening can be employed to screen high-risk populations for cancer and precancer, map the extension of OL lesions beyond what is visible, map the oral cavity for precancerous changes even when visible abnormalities are absent, test accuracy of promising imaging modalities, monitor interventions and determine genetic progression as well as the natural history of the disease in the human patient.  相似文献   
7.
8.
9.
Cyclotron-produced copper-64 radioisotope tracers offer the possibility to perform both diagnostic investigation by positron emission tomography (PET) and radiotherapy by a theranostic approach with bifunctional chelators. The versatile chemical properties of copper add to the importance of this isotope in medicinal investigation. [64Cu][Cu (ATSM)] has shown to be a viable candidate for imaging of tumor hypoxia; a critical tumor microenvironment characteristic that typically signifies tumor progression and resistance to chemo-radiotherapy. Various production and radiosynthesis methods of [64Cu][Cu (ATSM)] exist in labs, but usually involved non-standardized equipment with varying production qualities and may not be easily implemented in wider hospital settings. [64Cu][Cu (ATSM)] was synthesized on a modified GE TRACERlab FXN automated synthesis module. End-of-synthesis (EOS) molar activity of [64Cu][Cu (ATSM)] was 2.2–5.5 Ci/μmol (HPLC), 2.2–2.6 Ci/μmol (ATSM-titration), and 3.0–4.4 Ci/μmol (ICP-MS). Radiochemical purity was determined to be >99% based on radio-HPLC. The final product maintained radiochemical purity after 20 h. We demonstrated a simple and feasible process development and quality control protocols for automated cyclotron production and synthesis of [64Cu][Cu (ATSM)] based on commercially distributed standardized synthesis modules suitable for PET imaging and theranostic studies.  相似文献   
10.
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