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   1912篇
  免费   107篇
  国内免费   22篇
耳鼻咽喉   12篇
儿科学   36篇
妇产科学   19篇
基础医学   293篇
口腔科学   101篇
临床医学   122篇
内科学   495篇
皮肤病学   35篇
神经病学   80篇
特种医学   47篇
外科学   387篇
综合类   3篇
一般理论   1篇
预防医学   72篇
眼科学   7篇
药学   119篇
中国医学   2篇
肿瘤学   210篇
  2022年   21篇
  2021年   40篇
  2020年   35篇
  2019年   25篇
  2018年   32篇
  2017年   22篇
  2016年   27篇
  2015年   24篇
  2014年   34篇
  2013年   61篇
  2012年   65篇
  2011年   57篇
  2010年   50篇
  2009年   48篇
  2008年   73篇
  2007年   85篇
  2006年   78篇
  2005年   88篇
  2004年   70篇
  2003年   101篇
  2002年   90篇
  2001年   66篇
  2000年   92篇
  1999年   81篇
  1998年   48篇
  1997年   24篇
  1996年   29篇
  1995年   23篇
  1994年   19篇
  1993年   23篇
  1992年   60篇
  1991年   43篇
  1990年   54篇
  1989年   42篇
  1988年   44篇
  1987年   33篇
  1986年   25篇
  1985年   21篇
  1984年   10篇
  1983年   15篇
  1982年   12篇
  1980年   8篇
  1978年   16篇
  1977年   7篇
  1974年   20篇
  1973年   13篇
  1970年   9篇
  1969年   7篇
  1968年   10篇
  1966年   12篇
排序方式: 共有2041条查询结果,搜索用时 109 毫秒
81.
82.

Background

Intraoperative identification of the difficult-to-spot parathyroid gland is critical during surgery for thyroid and parathyroid disease. Recently, intrinsic fluorescence of the parathyroid gland was identified, and a new method was developed for intraoperative detection of the parathyroid with an original fluorescent detection apparatus. Here, we describe a method for intraoperative detection of the parathyroid using a ready-made photodynamic eye (PDE) system without any fluorescent dye or contrast agents.

Methods

Seventeen patients who underwent surgical treatment for thyroid or parathyroid disease at Kagoshima University Hospital were enrolled in this study. Intrinsic fluorescence of various tissues was detected with the PDE system. Intraoperative in vivo and ex vivo intrinsic fluorescence of the parathyroid, thyroid, lymph nodes and fat tissues was measured and analyzed.

Results

The parathyroid gland had a significantly higher fluorescence intensity than the other tissues, including the thyroid glands, lymph nodes and fat tissues, and we could identify them during surgery using the fluorescence-guided method. Our method could be applicable for two intraoperative clinical procedures: ex vivo tissue identification of parathyroid tissue and in vivo identification of the location of the parathyroid gland, including ectopic glands.

Conclusion

The PDE system may be an easy and highly feasible method to identify the parathyroid gland during surgery.
  相似文献   
83.
Background The role of surgical resection in patients with large or multinodular hepatocellular carcinoma (HCC) remains unclear. This study evaluated the long-term outcome of patients with hepatic resection for large (>5 cm in diameter) or multinodular (more than three nodules) HCC by using a multi-institutional database.Methods The perioperative and long-term outcomes of 404 patients with small HCC (<5 cm in diameter; group 1) were compared with those of 380 patients with large or multinodular HCC (group 2). The prognostic factors in the latter group were analyzed.Results The postoperative complication rate (27% vs. 23%; P = .16) and hospital mortality rate (2.4% vs. 2.7%; P = .82) were similar between groups. The overall survival rates were significantly higher in group 1 than group 2 (1 year, 88% vs. 74%; 3 years, 76% vs. 50%; 5 years, 58% vs. 39%; P < .001). Among patients in group 2, five independent prognostic factors were identified to be associated with a worse overall survival: namely, symptomatic disease, presence of cirrhosis, multinodular tumor, microvascular tumor invasion, and positive histological margin.Conclusions Hepatic resection can be safely performed in patients with large or multinodular HCC, with an overall 5-year survival rate of 39%. Symptomatic disease, the presence of cirrhosis, a multinodular tumor, microvascular invasion, and a positive histological margin are independently associated with a less favorable survival outcome.  相似文献   
84.
BACKGROUND: Carnitine is applied to ameliorate ischemia-reperfusion (I/R) injury of several organs. However, application to hepatic I/R injury is not frequently reported. The aim of this study was to elucidate the effect of exogenous carnitine administration to ameliorate the warm hepatic I/R injury. MATERIALS AND METHODS: Male Wistar rats were divided into two groups, a carnitine group (Car);100 mg/kg of l-carnitine administration and a control group (C); vehicle administration. Thirty minutes after administration, the left hepatic lobes were given 60-min ischemia and then reperfused. Plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutamate dehydrogenase (GLDH), tumor necrosis factor (TNF)-alpha, and lipoperoxides (LPO) were measured. Hepatic adenosine triphosphate (ATP) concentration was also measured. The hepatic blood flow was estimated using a Laser Doppler. The presence of apoptosis in the livers was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. RESULTS: In group Car, the blood flow of the left hepatic lobes was better recovered during the reperfusion period than in group C (P < 0.0001). Plasma levels of ALT, AST, GLDH, and TNF-alpha at 1 h after reperfusion were not significantly different between the groups. Although there were no statistical significances, ALT, AST, and TNF-alpha levels in group Car at 24 h after reperfusion tended to be higher than in group C. Plasma LPO levels were not different between the two groups. Also hepatic ATP concentration was not different between the two groups. TUNEL positive liver cells were visible only in group Car at 24 h after reperfusion, but not in the controls. CONCLUSIONS: Although carnitine administration improved the hepatic blood flow during the reperfusion period, we could not demonstrate a protective effect to the hepatic warm I/R injury.  相似文献   
85.
Y Yamaoka  M Kita  T Kodama  N Sawai  K Kashima    J Imanishi 《Gut》1997,41(4):442-451
Background—Helicobacter pyloristrains possessing the cagA gene are thought to induceinterleukin 8 (IL-8) in gastric mucosa. However, it is still unclearwhether a relation exists between the cagA gene and theexpression patterns of cytokines other than IL-8.
AimsTo investigate therelation between the cagA gene and the productionof various cytokine proteins using an enzyme linked immunosorbentassay (ELISA).
Patients and methodsIn 184 patients,the cagA gene was detected by polymerase chain reaction(PCR), and levels of production of IL-1β, IL-6, IL-7, IL-8, IL-10,and tumour necrosis factor α (TNF-α) in antral biopsy specimenswere measured by ELISA.
Results—Mucosal levels of IL-1β, IL-6,IL-8, and TNF-α were significantly higher in H pyloripositive than in H pylori negative patients.Furthermore, the mucosal levels of IL-1β and IL-8 were significantly higher in specimens infected with cagApositive strains than in those infected with cagAnegative strains. In H pylori positivepatients, the mucosal level of IL-8 was closely correlated withthat of IL-1β (p<0.0001), and the mucosal level of IL-6was closely correlated with that of TNF-α (p<0.0001).
Conclusion—These findings suggest that theability to induce cytokines differs among the strains;cagA+ strains induce various kinds ofcytokines and may cause severe inflammation, whereascagA strains induce IL-8 and IL-1β onlyweakly and may cause only mild inflammation. However, as most patientsinfected with the cagA+ strains havegastritis, these strains may not be equivalent to ulcerogenic strains.

Keywords:cytokines; Helicobacter pylori; cagA gene; interleukin 8; interleukin 1β

  相似文献   
86.
OBJECTIVES: The routes of human infection with Helicobacter pylori remain unclear. In the present study, we examined cockroaches as possible vectors for transmission of H. pylori. METHODS: We used a common species of cockroach (Periplaneta fuliginosa). After a 3-day fast, cockroaches were placed on agar plates containing freshly grown H. pylori (Sydney strain) (challenge group) or on sterile agar plates without H. pylori (control group). After 24 h of challenge, cockroaches were moved to disinfected containers, and sterile food and water were provided. The external surfaces (legs and body) and excreta of the cockroaches were sampled for culture, rapid urease test, and polymerase chain reaction (PCR). RESULTS: H. pylori were culturable from the excreta of the challenge group for 24 h postchallenge. Positive rapid urease test results were obtained up to day 3, and PCR analysis was positive for H. pylori DNA up to day 7 from the excreta. In contrast, H. pylori were not culturable from the external surfaces of the cockroaches. The rapid urease test was positive for only 8 h, and PCR analysis was positive for H. pylori DNA for 1 day from the external surface. CONCLUSIONS: Cockroaches usually live in unsanitary environments and may contaminate foods and food containment areas such as pantries. Transmission of H. pylori infection could be achieved via inadvertent ingestion of foods contaminated with cockroach excreta containing viable H. pylori.  相似文献   
87.
88.
Infection with Helicobacter pylori is linked to inflammation and is the main cause of peptic ulcer, gastritis, and gastric malignancies. To examine associations between gastric cancer risk and the erythrocyte composition of docosahexaenoic acid (DHA), a fatty acid with anti-inflammatory and apoptosis-inducing effects, here we conducted a case-control study of 179 incident gastric cancer cases and 357 noncancer controls (matched by age, sex, and season of sample collection). Dietary information and blood samples were collected from all subjects, and erythrocyte fatty acid levels were measured using accelerated solvent extraction and gas-liquid chromatography. Gastric cancer risk did not seem to be directly associated with dietary intake of fish and n-3 highly unsaturated fatty acids (HUFAs), such as DHA, derived from fish. However, risk was inversely associated with erythrocyte compositions of n-3 HUFAs [the highest to the lowest tertile, odds ratio (OR), 0.39; 95% confidence interval (95% CI), 0.23-0.68; P(trend)<0.005] and DHA (OR, 0.47; 95% CI, 0.28-0.79; P(trend)<0.01). Particularly strong associations were noted for well-differentiated type lesions and n-3 HUFAs (OR, 0.10; 95% CI, 0.03-0.35; P(trend)=0.0005) as well as DHA (OR, 0.20; 95% CI, 0.07-0.58; P(trend)<0.01) values. In conclusion, the erythrocyte composition of DHA was found to be negatively linked to risk of gastric cancer, especially of well-differentiated adenocarcinoma. Further studies are needed to investigate mechanisms of action of DHA relevant to antitumor effects in the stomach.  相似文献   
89.
A total of 16 patients with carcinoma in the cervicothoracic esophagus underwent pharyngolaryngoesophagectomy with construction of a mediastinal tracheostoma. Among them, seven patients underwent transhiatal esophagectomy without thoracotomy, four proximal esophagectomy by cervicotomy and sternal split, and five cervical and thoracic esophagectomy and lymphadenectomy by cervicotomy and right thoracotomy. Free jejunal transfer was performed to reconstruct the esophagus in five patients, and the stomachs were used in ten. One patient died of pneumonia 27 days after surgery, and two of arterial blowout. Plastic and reconstructive surgery techniques were introduced to protect large vessels and cover the wound. The postoperative 30-day mortality was 6.3% and the total operative mortality was 18.8%. Median survival was 327 days. Mediastinal tracheostomy is safely applicable today for patients with esophageal carcinoma invading the proximal trachea, allowing them to achieve safe respiration and to enjoy meals. © Wiley-Liss, Inc.  相似文献   
90.
A 1 11/12-year-old girl with osteogenesis imperfecta was treated with porcine calcitonin. Eight bone fractures occurred in the previous 20 months before therapy, but none occurred during eight months of therapy. There was also a significant improvement in linear growth and radiographic bone density. This is the first study of the effect of calcitonin on vitamin D metabolism in a human. The high plasma levels of 1,25 dihydroxy-vitamin D (1,25-(OH)2-D) and 24,25 dihydroxy-vitamin D (24,25-(OH)2-D) before calcitonin therapy decreased after therapy. Plasma 25 hydroxy-vitamin D (25-OH-D) concentration, which normal in level before calcitonin therapy, was normal or slightly decreased during administration. It is concluded that calcitonin probably influences vitamin D metabolism in a patient with osteogenesis imperfecta.  相似文献   
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