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   16756篇
  免费   1663篇
  国内免费   79篇
耳鼻咽喉   160篇
儿科学   413篇
妇产科学   396篇
基础医学   1052篇
口腔科学   93篇
临床医学   2260篇
内科学   3160篇
皮肤病学   58篇
神经病学   1113篇
特种医学   436篇
外科学   1939篇
综合类   1811篇
预防医学   2571篇
眼科学   41篇
药学   2424篇
  8篇
中国医学   230篇
肿瘤学   333篇
  2023年   318篇
  2022年   362篇
  2021年   701篇
  2020年   751篇
  2019年   615篇
  2018年   611篇
  2017年   612篇
  2016年   607篇
  2015年   580篇
  2014年   1130篇
  2013年   1373篇
  2012年   1057篇
  2011年   1093篇
  2010年   813篇
  2009年   789篇
  2008年   778篇
  2007年   751篇
  2006年   673篇
  2005年   574篇
  2004年   497篇
  2003年   439篇
  2002年   306篇
  2001年   299篇
  2000年   287篇
  1999年   239篇
  1998年   216篇
  1997年   199篇
  1996年   185篇
  1995年   255篇
  1994年   152篇
  1993年   128篇
  1992年   135篇
  1991年   135篇
  1990年   116篇
  1989年   87篇
  1988年   104篇
  1987年   78篇
  1986年   77篇
  1985年   83篇
  1984年   67篇
  1983年   41篇
  1982年   36篇
  1981年   27篇
  1980年   30篇
  1979年   22篇
  1978年   22篇
  1977年   16篇
  1975年   10篇
  1974年   5篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Slow recruitment in clinical trials leads to increased costs and resource utilization, which includes both the clinic staff and patient volunteers. Careful planning and monitoring of the accrual process can prevent the unnecessary loss of these resources. We propose two hierarchical extensions to the existing Bayesian constant accrual model: the accelerated prior and the hedging prior. The new proposed priors are able to adaptively utilize the researcher's previous experience and current accrual data to produce the estimation of trial completion time. The performance of these models, including prediction precision, coverage probability, and correct decision‐making ability, is evaluated using actual studies from our cancer center and simulation. The results showed that a constant accrual model with strongly informative priors is very accurate when accrual is on target or slightly off, producing smaller mean squared error, high percentage of coverage, and a high number of correct decisions as to whether or not continue the trial, but it is strongly biased when off target. Flat or weakly informative priors provide protection against an off target prior but are less efficient when the accrual is on target. The accelerated prior performs similar to a strong prior. The hedging prior performs much like the weak priors when the accrual is extremely off target but closer to the strong priors when the accrual is on target or only slightly off target. We suggest improvements in these models and propose new models for future research. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
4.
范晓鋆  陈伟 《安徽医学》2015,36(6):693-694
目的:评价新生儿黄疸动态监测的意义及早期不同干预治疗的临床疗效。方法对新生儿进行早期黄疸动态监测,将动态监测中发现胆红素超标的患儿随机分成蓝光治疗组、蓝光辅助茵栀黄治疗组、蓝光辅助妈咪爱(枯草杆菌二联活菌)治疗组和对照组,通过比较各组胆红素脑损伤的发生率及胆红素值的下降程度,客观评定新生儿早期黄疸监测的临床意义及不同干预治疗的临床疗效。结果治疗组黄疸峰值、高胆红素血症的发生率明显低于对照组,差异有统计学意义( P<0.05)。与单一蓝光治疗相比,蓝光治疗辅助茵栀黄或妈咪爱均能更有效降低胆红素值。结论动态监测黄疸可尽早发现胆红素水平的异常,为尽早干预治疗提供了保障。早期联合治疗能更有效降低胆红素,有效预防新生儿胆红素脑损伤的发生。  相似文献   
5.
The regression limited sampling strategy approach (R‐LSS), which is based on a small number of blood samples drawn at selected time points, has been used as an alternative method for the estimation of the area under the concentration–time curve (AUC). However, deviations from planned sampling times may affect the performance of R‐LSS, influencing related therapeutic decisions and outcomes. The aim of this study was to investigate the impact of different sampling time deviation (STD) scenarios on the estimation of AUC by the R‐LSS using a simulation approach. Three types of scenarios were considered going from the simplest case of fixed deviations, to random deviations and then to a more realistic case where deviations of mixed nature can occur. In addition, the sensitivity of the R‐LSS to STD in each involved sampling point was evaluated. A significant impact of STD on the performance of R‐LSS was demonstrated. The tolerance of R‐LSS to STD was found to depend not only on the number of sampling points but more importantly on the duration of the sampling process. Sensitivity analysis showed that sampling points at which rapid concentration changes occur were relatively more critical for AUC prediction by R‐LSS. As a practical approach, nomograms were proposed, where the expected predictive performance of R‐LSS was provided as a function of STD information. The investigation of STD impact on the predictive performance of R‐LSS is a critical element and should be routinely performed to guide R‐LSS selection and use. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
6.
Lung transplant recipients (LTR) at our institution receive prolonged and mostly lifelong azole antifungal (AF) prophylaxis. The impact of this prophylactic strategy on the epidemiology and outcome of invasive fungal infections (IFI) is unknown. This was a single‐center, retrospective cohort study. We reviewed the medical records of all adult LTR from January 2002 to December 2011. Overall, 16.5% (15 of 91) of patients who underwent lung transplantation during this time period developed IFI. Nineteen IFI episodes were identified (eight proven, 11 probable), 89% (17 of 19) of which developed during AF prophylaxis. LTR with idiopathic pulmonary fibrosis were more likely to develop IFI (HR: 4.29; 95% CI: 1.15–15.91; p = 0.03). A higher hazard of mortality was observed among those who developed IFI, although this was not statistically significant (hazard ratio [HR]: 1.71; 95% confidence interval [CI] [0.58–4.05]; p = 0.27). Aspergillus fumigatus was the most common cause of IFI (45%), with pulmonary parenchyma being the most common site of infection. None of our patients developed disseminated invasive aspergillosis, cryptococcal or endemic fungal infections. IFI continue to occur in LTR, and the eradication of IFI appears to be challenging even with prolonged prophylaxis. Azole resistance is uncommon despite prolonged AF exposure.  相似文献   
7.
8.
9.
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