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   251303篇
  免费   13307篇
  国内免费   2239篇
耳鼻咽喉   534篇
儿科学   2263篇
妇产科学   3255篇
基础医学   26579篇
口腔科学   840篇
临床医学   29139篇
内科学   111569篇
皮肤病学   2723篇
神经病学   9683篇
特种医学   5736篇
外国民族医学   4篇
外科学   24939篇
综合类   6530篇
现状与发展   9篇
一般理论   87篇
预防医学   10703篇
眼科学   883篇
药学   12124篇
  47篇
中国医学   1054篇
肿瘤学   18148篇
  2023年   5719篇
  2022年   7928篇
  2021年   10365篇
  2020年   9774篇
  2019年   6643篇
  2018年   7507篇
  2017年   7082篇
  2016年   7160篇
  2015年   7406篇
  2014年   14721篇
  2013年   13269篇
  2012年   12157篇
  2011年   11612篇
  2010年   10458篇
  2009年   9638篇
  2008年   9397篇
  2007年   9697篇
  2006年   9147篇
  2005年   8943篇
  2004年   7890篇
  2003年   7857篇
  2002年   7945篇
  2001年   7836篇
  2000年   7732篇
  1999年   6921篇
  1998年   2963篇
  1997年   2099篇
  1996年   1941篇
  1995年   1724篇
  1994年   1424篇
  1993年   1370篇
  1992年   5375篇
  1991年   4845篇
  1990年   4592篇
  1989年   3491篇
  1988年   3064篇
  1987年   1560篇
  1986年   585篇
  1985年   767篇
  1984年   656篇
  1983年   538篇
  1982年   521篇
  1981年   441篇
  1980年   414篇
  1979年   376篇
  1978年   392篇
  1977年   290篇
  1973年   219篇
  1972年   225篇
  1969年   210篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
BackgroundTo determine whether the short-term benefits associated with an enhanced recovery after surgery programme (ERAS) following pancreaticoduodenectomy (PD) vary with age.Methods830 consecutive patients who underwent PD between January 2009 and March 2019 were divided according to age: elderly (≥75 years) vs. non-elderly patients (<75 years). Within each age group, cohort characteristics and outcomes were compared between patients treated pre- and post-ERAS (ERAS was systematically introduced in December 2012). Univariable and multivariable analysis were then performed, to assess whether ERAS was independently associated with length of hospital stay (LOS).ResultsOf the entire cohort, 577 of 830 patients (69.5%) were managed according to an ERAS protocol, and 170 patients (20.5%) were aged ≥75 years old. Patients treated post-ERAS were significantly more comorbid than those pre-ERAS, with a mean Charlson Comorbidity Index of 4.6 vs. 4.1 (p < 0.001) and 6.0 vs. 5.7 (p = 0.039) for the non-elderly and elderly subgroups, respectively. There were significantly fewer medical complications in non-elderly patients treated post-ERAS compared to pre-ERAS (12.4% vs. 22.4%; p = 0.002), but not in elderly patients (23.6% vs. 14.0%; p = 0.203). On multivariable analysis, ERAS was independently associated with reduced LOS in both elderly (14.8% reduction, 95% CI: 0.7–27.0%, p = 0.041) and non-elderly patients (15.6% reduction, 95% CI: 9.2–21.6%, p < 0.001), with the effect size being similar in each group.ConclusionERAS protocols can be safely applied to patients undergoing pancreaticoduodenectomy irrespective of age. Implementation of an ERAS protocol was associated with a significant reduction in postoperative LOS in both elderly and non-elderly patients, despite higher comorbidity in the post-ERAS period.  相似文献   
5.
Although methadone is effective in the management of acute pain, the complexity of its absorption-distribution-metabolism-excretion profile limits its use as an opioid of choice for perioperative analgesia. Because deuteration is known to improve the pharmacokinetic, pharmacodynamic and toxicological properties of some drugs, here we characterized the single dose pharmacokinetic properties and post-operative analgesic efficacy of d9-methadone.The pharmacokinetic profiles of d9-methadone and methadone administered intravenously to CD-1 male mice revealed that deuteration leads to a 5.7- and 4.4-fold increase in the area under the time-concentration curve and maximum concentration in plasma, respectively, as well as reduction in clearance (0.9 ± 0.3 L/h/kg vs 4.7 ± 0.8 L/h/kg). The lower brain-to-plasma ratio of d9-methadone compared to that of methadone (0.35 ± 0.12 vs 2.05 ± 0.62) suggested that deuteration decreases the transfer of the drug across the blood-brain barrier. The estimated LD50 value for a single intravenous dose of d9-methadone was 2.1-fold higher than that for methadone. Moreover, d9-methadone outperformed methadone in the efficacy against postoperative pain by primarily activating peripheral opioid receptors. Collectively, these data suggest that the replacement of three hydrogen atoms in three methyl groups of methadone altered its pharmacokinetic properties, improved safety, and enhanced its analgesic efficacy.  相似文献   
6.
7.
Microbeads and fragments have been widely studied, while glitter remains neglected by the literature although found in a variety product (e.g., body paints, nail polish, cosmetics, craft products). The main aim of this study was to assess the effects of different types and concentrations of glitter particles on Mytilus galloprovincialis after 7 days of exposure. The experiment was divided into a preliminary test and a confirmatory test. Our findings support the hypothesis for a link between concentration and type of glitter particles, percentage of recovery and oxidative stress in M. galloprovincialis. There was a significant correlation between particle length and percentage of particles recovered in water, suggesting that the digestive tract of M. galloprovincialis retains smaller particles more. In addition, we noted an increase in antioxidant defense induced by smaller particles. Moreover, certain types of glitter crumbled and shortened in length, resulting in higher levels of oxidative stress biomarkers. Finally, the star-shaped glitter particles had a different effect on oxidative stress biomarkers. Further studies are needed to clarify the toxic effects of glitter on aquatic organisms and to quantify its proportion to other microplastics in the environment.  相似文献   
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