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   1585篇
  免费   71篇
  国内免费   11篇
耳鼻咽喉   54篇
儿科学   126篇
妇产科学   57篇
基础医学   131篇
口腔科学   100篇
临床医学   173篇
内科学   314篇
皮肤病学   69篇
神经病学   96篇
特种医学   77篇
外科学   225篇
综合类   24篇
预防医学   31篇
眼科学   33篇
药学   81篇
中国医学   3篇
肿瘤学   73篇
  2024年   2篇
  2023年   18篇
  2022年   20篇
  2021年   44篇
  2020年   21篇
  2019年   51篇
  2018年   36篇
  2017年   31篇
  2016年   56篇
  2015年   65篇
  2014年   85篇
  2013年   98篇
  2012年   122篇
  2011年   128篇
  2010年   75篇
  2009年   60篇
  2008年   124篇
  2007年   139篇
  2006年   129篇
  2005年   107篇
  2004年   96篇
  2003年   85篇
  2002年   35篇
  2001年   15篇
  2000年   7篇
  1999年   6篇
  1998年   4篇
  1997年   4篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
排序方式: 共有1667条查询结果,搜索用时 343 毫秒
71.
The etiology of autism is unclear, however autism is considered as a multifactorial disorder that is influenced by neurological, environmental, immunological and genetic factors. Growth factors, including epidermal growth factor (EGF), play an important role in the celluler proliferation and the differentiation of the central and peripheral nervous system. In this study we hypothesized that EGF may play a role in the pathophysiology of autism and examined serum EGF levels in children with autism. We measured serum levels of EGF in the 27 autistic children and 28 age- matched normal controls. The serum levels of EGF in the subjects with autism were significantly higher than those of normal control subjects. However, there were no correlations between serum EGF levels and clinical variables in the subjects with autism. This is the first report demonstrating the increased serum levels of EGF in children with autism. This study suggests that increased levels of EGF might have an importance in the pathophysiology of autism.  相似文献   
72.
The objective is to compare the success rates of revision endonasal dacryocystorhinostomy (END-DCR) with revision external dacryocystorhinostomy (EXT-DCR). The present retrospective study was conducted between January 2002 and July 2009. Seventy-four consecutive patients (17 males, 57 females) who had epiphora or recurrent dacryocystitis after a previous failed EXT-DCR procedure were enrolled in the study. The END-DCR group consisted of 43 patients (10 males, 33 females) who underwent 44 END-DCRs, whereas the EXT-DCR group included 31 patients (7 males, 24 females) who underwent 31 dacryocystorhinostomies (DCRs). Successful DCR was defined as relief of symptoms as demonstrated by saline irrigation at the last post-operative visit. Further nasal surgery was performed in 18 (40.9%) eyes in the END-DCR group. The average follow-up time for the END-DCR and EXT-DCR groups was 11 and 9?months, respectively. The success rate was 77.4% (24/31 DCRs) in the END-DCR group, and 84.1% (37/44 DCRs) in the EXT-DCR group. There was no significant difference between the groups regarding overall success (p?=?0.465). END-DCR is as safe and efficient technique as external approach with low complication rates in revision cases. END-DCR yields good esthetic and functional results and has a success rate similar to that of the external approach.  相似文献   
73.
74.
75.
The seroprevalence of Helicobacter pylori and nitric oxide in acne rosacea   总被引:5,自引:0,他引:5  
BACKGROUND: Acne rosacea is a dermatosis with unknown etiology. Some studies have reported a high prevalence of Helicobacter pylori infection in acne rosacea. Other studies have reported a decrease in the severity of the lesions of acne rosacea after eradication of H. pylori. H. pylori is a Gram-negative bacterium which colonizes the gastric mucosa and increases the synthesis of oxygen radicals, such as superoxide and proinflammatory cytokines. These cytokines have been demonstrated to stimulate the synthesis of the inflammatory species nitric oxide (NO). In this study, we examined the role of NO in the possible effect of H. pylori in acne rosacea. METHODS: Thirty-three acne rosacea patients were included in the study and the control group comprised 20 healthy individuals. The levels of immunoglobulin G antibodies against H. pylori in the serum samples were measured using the enzyme-linked immunoabsorbent assay method. Measurement of nitrate was performed using chemiluminescence in accordance with the method described by Braman and Hendrix (Braman RS, Hendrix SA. Nanogram nitrite and nitrate determination in environmental and biological materials by vanadium(iii) reduction with chemiluminescence detection. Anal Chem 1989; 61: 2715-2718). For statistical analysis, the t-test was used. RESULTS: The seropositivity of H. pylori in acne rosacea patients was found to be high; however, the serum nitrate levels were found to be normal. CONCLUSIONS: The results of the study indicate that the inflammatory species NO, which has been hypothesized to be associated with H. pylori, has no role in the inflammatory mechanism of acne rosacea.  相似文献   
76.
The authors report a case of alveolar soft-part sarcoma with lung metastases demonstrated by "double imaging" with Tc-99m HDP and Tc-99m MIBI. The tumor originated in the soft tissue with direct invasion to the right scapula, which was hypoactive on bone scan and hyperactive on Tc-99m MIBI images. A focus of dense accumulation of Tc-99m MIBI in the lungs, suggesting metastasis was also demonstrated.  相似文献   
77.
Serological markers for Chlamydia pneumoniae were investigated by using the microimmunofluorescence (MIF) test in various age and patient groups in a specific area in Turkey. IgG seropositivity to C. pneumoniae was 64.3% and 18.7% in healthy adults and children, respectively. The highest positivity rate (77%) was in the 15–19 age group. Among the groups investigated, serological findings revealed a possible etiological association between C. pneumoniae and the clinical condition in the groups with acute myocardial infarction, atypical pneumoniae and chronic obstructive pulmonary disease.  相似文献   
78.
Mitomycin C prevents strictures in caustic esophageal burns in rats   总被引:2,自引:0,他引:2  
BACKGROUND: Caustic esophageal injuries lead to stricture formation. Although a number of agents have been tried experimentally to prevent strictures, few have gained clinical application. The purpose of this study was to investigate the effectiveness of Mitomycin C (MMC), which inhibits fibroblastic proliferation in preventing caustic esophageal strictures. MATERIAL AND METHODS: Fifty-six rats were allocated into four groups. Caustic esophageal burns were created as described by Gehanno. Group A was instilled only with saline. Group B was injured and untreated. Groups C and D were injured and received topical MMC at 0.02 and 0.04% concentrations, respectively. At 28 days, stenosis index (SI), collagen deposition, and hydroxyproline content (HP) were determined in distal esophageal segments. Statistical analyses were done. RESULTS: Mean SI in Group B was significantly higher than others (P < 0.05). Mean SI was statistically higher in Group C than A and D and similar between groups A and D. The greatest accumulation of collagen was found in Group B, followed by Group C, D, and A, respectively. Collagen deposition in Group D was statistically lower than Group B (P < 0.01) and similar to Group C. Mean HP in Group B was statistically higher than others (P < 0.05), significantly higher in Group C than Group D (P = 0.047), and similar between Groups A and D (P = 0.73). CONCLUSION: MMC was effective in preventing strictures following experimental caustic esophageal injury, in a dose-dependent manner. We consider that it can gain clinical utilization with the establishment of effective mode, dose, and timing of therapy.  相似文献   
79.
BACKGROUND: Translocating enteric bacteria have been suggested as playing a major role in the development of infections after partial hepatectomy. We investigated the effect of N-acetylcysteine (NAC) on bacterial translocation (BT) and intestinal mucosa as the first line of defense against BT. MATERIALS AND METHODS: We compared four groups of eight Sprague-Dawley male rats each: sham, control (partially hepatectomized), partial hepatectomy plus preoperative single-dose NAC, and a fourth that received partial hepatectomy with a preoperative single-dose NAC plus treatment with NAC for 2 days. Microorganism counts of tissues, lung injury score, lung tissue glutathione, and malondialdehyde levels and microscopy of intestinal mucosa were studied at the end of 48 h. RESULTS: Microorganism count in the lung and mesenteric lymph node cultures and lung injury score were significantly higher in the control group when compared with the sham, third, and fourth groups (lung: 9919.6 versus 0.0, 2912.9, 1550.0 cfu/g tissue; mesenteric lymph nodes: 8458.3 versus 0.0, 89.0, 88.9 cfu/g tissue; lung injury score: 3.25 versus 0.5, 1.13, 1.75). In the control group, the villous height of the distal ileal mucosa was significantly shorter than the sham group (65.25 versus 75.25 microm) and the difference from groups 3 and 4 was not statistically significant. Neutrophil infiltration in the distal ileal mucosa of the control group was significantly higher than the sham, third and fourth groups (3.13 versus 0.25, 0.38 and 1.0). CONCLUSIONS: The parenteral use of NAC attenuates bacterial translocation after partial hepatectomy in rats. Attenuation of the lung injury after partial hepatectomy in NAC-treated groups might be attributable to both anti-inflammatory effect and the effect on BT.  相似文献   
80.
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