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   13241篇
  免费   638篇
  国内免费   51篇
耳鼻咽喉   143篇
儿科学   299篇
妇产科学   323篇
基础医学   1629篇
口腔科学   273篇
临床医学   893篇
内科学   3280篇
皮肤病学   267篇
神经病学   953篇
特种医学   340篇
外科学   2271篇
综合类   40篇
预防医学   454篇
眼科学   249篇
药学   1330篇
中国医学   21篇
肿瘤学   1165篇
  2022年   146篇
  2021年   231篇
  2020年   134篇
  2019年   178篇
  2018年   201篇
  2017年   181篇
  2016年   211篇
  2015年   221篇
  2014年   296篇
  2013年   395篇
  2012年   573篇
  2011年   686篇
  2010年   321篇
  2009年   312篇
  2008年   576篇
  2007年   553篇
  2006年   562篇
  2005年   555篇
  2004年   574篇
  2003年   554篇
  2002年   562篇
  2001年   442篇
  2000年   436篇
  1999年   380篇
  1998年   166篇
  1997年   114篇
  1996年   96篇
  1995年   86篇
  1994年   84篇
  1993年   79篇
  1992年   354篇
  1991年   295篇
  1990年   304篇
  1989年   315篇
  1988年   304篇
  1987年   297篇
  1986年   261篇
  1985年   208篇
  1984年   187篇
  1983年   150篇
  1982年   83篇
  1979年   153篇
  1978年   82篇
  1977年   75篇
  1975年   83篇
  1973年   68篇
  1972年   73篇
  1971年   81篇
  1969年   70篇
  1968年   64篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Background: The placement of an endotracheal tube (ETT) may promote laryngeal swelling, which is an important cause of upper airway obstruction after extubation. The authors hypothesized that laryngeal swelling after ETT placement increases laryngeal resistance and tested that hypothesis by comparing postoperative laryngeal patency between patients with ETT placement and those with a Laryngeal Mask Airway(TM) (LMA(TM)).

Methods: Fourteen adult patients who underwent elective minor surgeries were randomly allocated to two groups whose airway would be managed through ETTs (the ETT group) or LMAs(TM) (the LMA(TM) group) during the surgery. While maintaining at sevoflurane 1 minimum alveolar concentration, the authors measured laryngeal resistance before and after surgery, during both spontaneous breathing and mechanical ventilation under complete paralysis. In addition, they endoscopically measured the vocal cord angle under complete paralysis.

Results: In association with marked swelling of the vocal cords, the vocal cord angle significantly decreased after surgery in the ETT group, whereas the angle did not change in the LMA group. Laryngeal resistance during mechanical ventilation significantly increased only in the ETT group. Laryngeal resistance during spontaneous breathing significantly increased after surgeries in both groups.  相似文献   

52.
Background: Pancreatic carcinoma is one of the most lethal cancers. Because pancreatic carcinoma is still very difficult to diagnose in its early stage, many of these patients will be considered unsuitable for surgery. If a cytological diagnosis is obtained at initial endoscopic retrograde cholangiopancreatography (ERCP), suitable treatment will be initiated without delay. Methods: To increase the number of exfoliated cells from the pancreatic duct, we devised a new technique, pancreatic duct lavage fluid (PDLF), following bronchoalveolar lavage fluid. The present paper reports the effectiveness of cytological examination using PDLF in the diagnosis of pancreatic carcinoma. We examined 18 pancreatic carcinoma cases. After the endoscopic retrograde pancreatography (ERP), PDLF was collected from a double‐lumen catheter inserted into the main pancreatic duct. Saline injected from the lumen for the injection, and PDLF was aspirated from the other lumen for the guidewire at the same time. The cytological examination was performed using PDLF. Results: Exfoliated cells were more frequently found in PDLF from all patients. In 15 cases (83%), cytological examination of PDLF revealed positive cytological results as the diagnosis of pancreatic carcinoma. Conclusion: Cytological examination using PDLF has a high sensitivity for detection of pancreatic carcinoma. The new examination, PDLF, is simple, safe and effective, so we expect PDLF to become widely popular.  相似文献   
53.
The patient was a one-year-old boy, who underwent surgery with a diagnosis of atrial septal defect (ASD). During operation, aorto-pulmonary window (A-P window) which had not been detected by the preoperative examinations, was found. Therefore, the A-P window was divided prior to closing ASD. The patient is in good condition six months after the operation. The causes of the inaccurate preoperative diagnosis were discussed.  相似文献   
54.
55.
Possible involvement of increased mucosal permeability in the stimulation by prostaglandin E2 (PGE2) of duodenal HCO3- secretion was investigated in rats. PGE2 (0.3, 1 mg/kg, s.c.) dose-dependently increased HCO3- secretion in the duodenum with a significant elevation of transmucosal potential difference (PD); the PD was increased from -4.5 +/- 0.3 mV to -10.0 +/- 1.5 mV (mucosa negative) at 1 mg/kg. These responses caused by PGE2 were abolished by sacrificing the animals with saturated KCl (i.v.). Although a significant increase of HCO3- output was observed after exposure of the mucosa to 1 M NaCl (0.5 ml), this response was accompanied by a significant reduction of PD and was not abolished after KCl injection. The mucosal permeability determined by Evans blue (1%, i.v.) was not affected by PGE2, while 1 M NaCl markedly elevated the amount of extravasated dye in both the luminal content and the mucosa. Stimulation of HCO3- output by PGE2 was significantly mitigated by ouabain (3 mg/kg, s.c.) or prior exposure of the mucosa to 1 M NaCl. These results suggest that stimulation by PGE2 of duodenal HCO3- secretion is not simply due to the increased mucosal permeability, but depends rather on both the Na/K ATPase activity and the intact perfusion of the organ. The HCO3- response as induced by 1 M NaCl may result from the increased permeability and is accompanied by a marked reduction of PD.  相似文献   
56.
Transurethral lithotripsy (TUL) was performed in the cases in which the ureteral calculi were not destroyed by the extracorporeal shock-wave lithotriptor (Dornier HM-3, EDAP LT 01). Preoperative placement of double-J ureteral catheter (D-J catheter) caused ureteral dilation, allowing smooth insertion of the ureteroscope. We divided the 55 TUL cases into two groups, those with (27) or without (28) a D-J catheter placed preoperatively, and compared requirement of ureteral bougination, difficulty of ureteroscope insertion and duration of operation between the two groups. In all cases with a D-J catheter, ureteral bougination was not necessary, the insertion of ureteroscope was easier and the duration of operation was shorter than the cases without a D-J catheter. Bladder irritable symptoms were seen in some cases with a D-J catheter but did not require removal of the D-J catheter. On the follow-up term after TUL, there was no difference in the incidence of postoperative fever or postoperative ureteral stenosis, between the cases with and those without a D-J catheter.  相似文献   
57.
58.
Beta-core fragment (beta-CF), a fragment of the hCG beta-subunit missing its carboxyterminal peptide, can be detected in the urine of women throughout pregnancy or in trophoblastic disease. It is also found in the urine of patients with nontrophoblastic cancers. We examined the beta-CF level in urine samples from patients with cervical cancer and assessed its value as a tumor marker. beta-CF was measured by an enzyme immunoassay with hCG beta-core directed monoclonal antibody No. 229. Based on the cut-off value (0.2ng/ml) from control subjects, the overall positivity rate for urinary beta-CF in the cervical cancer group was 45% (57 of 128 patients), increasing from 32% (23 of 73) in stage I to 100% (2 of 2) in stage IV. These positivity rates exceeded or equaled those of the other markers, SCC, CEA, CA19-9 and CA125, simultaneously measured in the patients' serum. There was no significant difference between the positivity rates for the two histological types of cancer, squamous cell carcinoma and adenocarcinoma. Serial determination in 28 patients with increased urinary beta-CF prior to therapy showed that 24 patients had a decreased concentration after successful treatment, but 2 of 4 patients with still increased urinary beta-CF during or after treatment subsequently relapsed. The determination of urinary beta-CF may provide a useful tool in monitoring the response to treatment in patients with cervical cancer.  相似文献   
59.
60.
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