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   2587636篇
  免费   185084篇
  国内免费   7570篇
耳鼻咽喉   34274篇
儿科学   85202篇
妇产科学   71580篇
基础医学   363624篇
口腔科学   69681篇
临床医学   234522篇
内科学   515634篇
皮肤病学   62459篇
神经病学   213447篇
特种医学   99904篇
外国民族医学   736篇
外科学   386439篇
综合类   50392篇
现状与发展   5篇
一般理论   968篇
预防医学   196181篇
眼科学   56671篇
药学   187997篇
  8篇
中国医学   5331篇
肿瘤学   145235篇
  2021年   19991篇
  2019年   20636篇
  2018年   29298篇
  2017年   22601篇
  2016年   26233篇
  2015年   29504篇
  2014年   40444篇
  2013年   60435篇
  2012年   80243篇
  2011年   84491篇
  2010年   51003篇
  2009年   49148篇
  2008年   79028篇
  2007年   83852篇
  2006年   85593篇
  2005年   81750篇
  2004年   78740篇
  2003年   76060篇
  2002年   73342篇
  2001年   128408篇
  2000年   131336篇
  1999年   110501篇
  1998年   31255篇
  1997年   27920篇
  1996年   28217篇
  1995年   27383篇
  1994年   25067篇
  1993年   23420篇
  1992年   85166篇
  1991年   81565篇
  1990年   78785篇
  1989年   76064篇
  1988年   69470篇
  1987年   68001篇
  1986年   63542篇
  1985年   60512篇
  1984年   44941篇
  1983年   37946篇
  1982年   22459篇
  1981年   19990篇
  1979年   38960篇
  1978年   27443篇
  1977年   23253篇
  1976年   21499篇
  1975年   22814篇
  1974年   26791篇
  1973年   25375篇
  1972年   23750篇
  1971年   21955篇
  1970年   20184篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Background and objective  The purpose of this study is to assess whether Chinese children with high apnea–hypopnea index (AHI) are sleepier by a modified Epworth Sleepiness Scale (ESS). Materials and methods  Records were retrospectively reviewed. We included children who were between 3 and 12 years old, admitted for overnight polysomnogram because of suspected obstructive sleep apnea syndrome (OSAS). A modified ESS was used to assess excessive daytime sleepiness (EDS) of the children. Results  One hundred ninety-two Chinese children were included. Children with high AHI, defined as AHI > 5.0, were sleepier than children with AHI less than or equal to 5. After adjustment by age, gender, and obesity, children with high AHI remained significantly sleepier. Modified ESS was significantly correlated with AHI (rho = 0.124, 95% CI = 0.004–0.281). Modified ESS score of >8 was the best cutoff point with the sensitivity and specificity of 0.29 and 0.91, respectively. The odds ratio of children with modified ESS > 10 having high AHI was 4.231 (95%CI = 1.248 to 14.338) and children with modified ESS > 8 had the highest odds ratio, 4.295(95%CI = 1.66 to 11.1), of having high AHI. Conclusion   Chinese children with high AHI appear to be sleepier than children with low AHI. Children with suspected OSAS and high modified ESS, i.e., ESS > 8, had significantly higher odds ratio of having high AHI. Increased sleepiness is a specific but not a sensitive symptom in snoring children with high AHI. Screening for EDS in snoring children may help us identify those with high AHI and prioritize the management of those children. All authors worked and the study was carried out in Kwong Wah Hospital in Hong Kong. There was no conflict of interest and no specific source of funding for the study.  相似文献   
992.
V. Felmine  M. Zuleika 《Anaesthesia》2009,64(10):1130-1133
Following thoraco-abdominal oesophagogastrectomy for an adenocarcinoma of the lower oesophagus, an 81-year-old female with no pre-existing respiratory disease could not be weaned from mechanical ventilation. Right upper and middle lobe torsion were found at thoracotomy on the 14th postoperative day. Both lobes were resected. The patient was discharged from hospital after several postoperative complications. Pulmonary torsion is a rare, potentially life-threatening complication of thoraco-abdominal oesophagogastrectomy. Differentiation from the more common postoesophagectomy pulmonary complications can be difficult. Early post-thoracotomy lung opacification, in the absence of the expected degree of hypoxaemia, should trigger a suspicion of pulmonary torsion.  相似文献   
993.
994.
995.
996.
997.
998.
999.
PTH has diverse effects on bone metabolism: anabolic when given intermittently, catabolic when given continuously. The cellular mechanisms underlying the varying target cell response are not clear yet. PTH induces RGS-2, a member of the Regulator of G-protein Signaling protein family, via cAMP/PKA, and inactivates PKC-mediated signaling. To investigate intracellular signaling pathways with different PTH concentration-time patterns, we treated UMR 106-01 osteoblast-like cells in a perfusion system. PTH was administered intermittently (4 min/h, 10−7 M) or continuously at an equivalent cumulative dose (6.6 × 10−9 M). cAMP was measured using radioimmunoassay, mRNA levels using real-time rtPCR and ribonuclease protection assay, and protein levels using Western immunoblotting. A single PTH pulse transiently increased cAMP levels by 2000% ± 1200%. In contrast to continuous PTH exposure, cAMP induction remained unchanged with intermittent PTH, ruling out desensitization of the PTH receptor. In continuously perfused cells, RGS-2 abundance was three to five times higher than in cells intermittently exposed to PTH for up to 12 h. MKP-1 and -3 were significantly less induced with pulsatile PTH; exposure-mode-dependent differences in MMP-13 and IGFBP-5 were small. Pulsatile but not continuous PTH administration prevents PTHrP receptor desensitization and accumulation of RGS-2 in osteoblasts, which should preserve PKC-dependent signaling.  相似文献   
1000.
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