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   1800篇
  免费   118篇
  国内免费   13篇
耳鼻咽喉   11篇
儿科学   55篇
妇产科学   49篇
基础医学   239篇
口腔科学   29篇
临床医学   220篇
内科学   474篇
皮肤病学   28篇
神经病学   188篇
特种医学   59篇
外科学   146篇
综合类   7篇
预防医学   135篇
眼科学   36篇
药学   125篇
肿瘤学   130篇
  2023年   22篇
  2022年   9篇
  2021年   68篇
  2020年   55篇
  2019年   63篇
  2018年   62篇
  2017年   51篇
  2016年   52篇
  2015年   69篇
  2014年   90篇
  2013年   107篇
  2012年   160篇
  2011年   138篇
  2010年   96篇
  2009年   91篇
  2008年   135篇
  2007年   127篇
  2006年   120篇
  2005年   100篇
  2004年   103篇
  2003年   76篇
  2002年   67篇
  2001年   10篇
  2000年   6篇
  1999年   7篇
  1998年   13篇
  1997年   5篇
  1996年   5篇
  1995年   8篇
  1994年   4篇
  1993年   1篇
  1992年   5篇
  1987年   1篇
  1984年   1篇
  1983年   1篇
  1978年   1篇
  1975年   1篇
  1973年   1篇
排序方式: 共有1931条查询结果,搜索用时 62 毫秒
991.
The aim of the current study was to compare the association of several anthropometric indices, with insulin resistance (IR) proxy measures in European adolescents. The present study comprises 1,097 adolescents aged 12.5-17.5 from ten European cities participating in the HELENA study. Weight, height, waist circumference (WC) and hip circumference, skinfolds thickness, fat mass (FM), fasting plasma glucose (G(F)) and serum insulin (I(F)) levels were measured. HOMA (as indicator of IR body mass index (BMI), waist to hip ratio (WHR) and waist to height ratio (WHtR) were calculated. I(F) and HOMA were statistically significantly related to BMI, WC, skinfold sum, WHtR, WHR and FM. BMI, WC, WHtR, skinfold sum and FM displayed similar correlation with I(F) and HOMA as opposed to WHR where lower correlation with IR indices was detected in the overall sample. Similar results were found for boys, girls and underweight/normal weight adolescents. On the other hand, WC and WHtR were found to be more strongly associated with IR proxy measures compared to the rest of anthropometric indices among overweight/obese subjects. Based on the current findings, WC and WHtR could be used, alternatively, to identify the overweight/obese adolescent at risk for developing IR. In addition, all aforementioned anthropometric indices, except WHR, could be used among the underweight/normal weight adolescents.  相似文献   
992.
993.
BACKGROUND: Percutaneous metal stenting is an accepted palliative treatment for malignant biliary obstruction. Nevertheless, factors predicting survival are not known. METHODS: Seventy-six patients with inoperable malignant biliary obstruction were treated with percutaneous placement of metallic stents. Twenty patients had non-hilar lesions. Fifty-six patients had hilar lesions classified as Bismuth type I (n = 15 patients), type II (n = 26), type III (n = 12), or type IV (n = 3 patients). Technical and clinical success rates, complications, and long-term outcome were recorded. Clinical success rates, patency, and survival rates were compared in patients treated with complete (n = 41) versus partial (n = 35) liver parenchyma drainage. Survival was calculated and analyzed for potential predictors such as the tumor type, the extent of the disease, the level of obstruction, and the post-intervention bilirubin levels. RESULTS: Stenting was technically successful in all patients (unilateral drainage in 70 patients, bilateral drainage in 6 patients) with an overall significant reduction of the post-intervention bilirubin levels (p < 0.001), resulting in a clinical success rate of 97.3%. Clinical success rates were similar in patients treated with whole-liver drainage versus partial liver drainage. Minor and major complications occurred in 8% and 15% of patients, respectively. Mean overall primary stent patency was 120 days, while the restenosis rate was 12%. Mean overall secondary stent patency was 242.2 days. Patency rates were similar in patients with complete versus partial liver drainage. Mean overall survival was 142.3 days. Survival was similar in the complete and partial drainage groups. The post-intervention serum bilirubin level was an independent predictor of survival (p < 0.001). A cut-off point in post-stenting bilirubin levels of 4 mg/dl dichotomized patients with good versus poor prognosis. Patient age and Bismuth IV lesions were also independent predictors of survival. CONCLUSIONS: Percutaneous metallic biliary stenting provides good palliation of malignant jaundice. Partial liver drainage achieved results as good as those after complete liver drainage. A serum bilirubin level of less than 4 mg/dl after stenting is the most important independent predictor of survival, while increasing age and Bismuth IV lesions represent dismal prognostic factors.  相似文献   
994.
A 74-year-old man presented with a ruptured infected anastomotic femoral pseudoaneurysm. Due to severe medical comorbidities he was considered unsuitable for conventional surgical management and underwent an emergency endovascular repair with a balloon-expandable covered stent. The pseudoaneurysm was excluded successfully and the patient had an uneventful postoperative recovery with long-term suppressive antimicrobials. He remained well for 10 months after the procedure with no signs of recurrent local or systemic infection and finally died from an acute myocardial infarction. To our knowledge, emergency endovascular treatment of a free ruptured bleeding femoral artery pseudoaneurysm has not been documented before in the English literature. This case illustrates that endovascular therapy may be a safe and efficient alternative in the emergent management of ruptured infected anastomotic femoral artery pseudoaneurysms when traditional open surgery is contraindicated.  相似文献   
995.
Serotonin, the major secretory product of activated platelets, has been widely reported as regulating various constituents of the immune system and immune functions. This modulation is complex and the data available are rather controversial. The aim of the present study was to clarify the mechanisms of serotonin action on human phagocytes. The effect of serotonin in a concentration range of 10(-7) M-10(-3) M on various parameters of oxidative burst of phagocytes was studied using various luminol-enhanced chemiluminescence methods. Serotonin inhibited the chemiluminescence response of the cells in a dose dependent manner. The effect of serotonin on the activity of myeloperoxidase was studied in further experiments. In this case, serotonin again exerted a dose dependent inhibition of the myeloperoxidase activity. The hypothesis that the inhibitory activity of serotonin might be also receptor mediated was evaluated using various serotonin receptor agonists and antagonists. None of the agonists studied exerted any direct antioxidative properties. Only (+/-)-DOI hydrochloride, a selective 5-HTR(2) agonist, exerted similar effects on phagocytic cells as serotonin. It can be concluded that serotonin could affect the oxidative burst of phagocytes. Responsibility for its inhibitory effects lies with both the decrease in the generation of reactive oxygen species (due to the inhibition of myeloperoxidase activity) and with direct scavenging of reactive oxygen species. The effect of serotonin on phagocytes is also partially mediated by 5-HTR(2) receptor.  相似文献   
996.
BACKGROUND: Primary Sj?gren's syndrome (pSs) is an autoimmune rheumatic disease that may express in a small number of patients a spectrum of lymphoproliferative diseases. The aim of this study was to describe clinical, imaging and pathology features of the extranodal marginal zone B-cell lymphoma (MZCL) of the lung of mucosa-associated lymphoid tissue (MALT) type in patients with pSs. METHODS: All patients (N=10) with biopsy proven MZCL of the lung of MALT type diagnosed in a tertiary teaching hospital during the last 7 years were studied. RESULTS: Seven patients had pSs. Almost all patients presented an indolent clinical course, contrasting strongly with the spectacular radiological findings in both chest roentgenograms and computed tomography. Pathology infiltration patterns observed were either nodular, peribronchial-perivascular, alveolar, or interstitial. Immunohistochemical study in all cases showed B cell phenotypes. Immunoglobulin light chain restriction was demonstrated in all patients. Monoclonal IgM(kappa) was evident in 5/7, IgM(lambda) in 1/7 and IgG (kappa) in 1/7 of patients. CONCLUSIONS: Lung MZCL associated with pSs are characterized by an important dissociation between clinical expression and radiological pattern. Clinical presentation and imaging features are not specific. Therefore, histologic documentation is mandatory to ensure diagnosis. Various chemotherapeutic agents in combination with rituximab lead to partial or complete remission in the majority of patients.  相似文献   
997.
998.
Barrett's esophagus (BE) is a premalignant lesion in which columnar epithelium (containing goblet cells) replaces esophageal squamous cells. Previous evidence suggested that hydrophobic bile acids and zinc deficiency each play a role in BE development. We fed wild-type C57BL/6 mice a zinc-deficient diet containing the hydrophobic bile acid, deoxycholic acid for various times up to 152 days. All mice fed this diet developed esophagitis by 69 days on the diet and 63% of the mice on this diet for 88 to 152 days also developed a BE-like lesion. Esophageal tissues showed thickened mucosa, increased proliferation, and increased expression of markers associated with oxidative and nitrosative stress. The newly formed BE-like lesions expressed Mucin-2, a marker of columnar differentiation. They also showed translocation of the p65 subunit of nuclear factor-kappaB and beta -catenin to the nucleus and typical histological changes associated with BE lesions. This mouse model of esophagitis and BE is expected to contribute to a deeper understanding of BE pathogenesis and to strategies for prevention of BE progression to cancer.  相似文献   
999.
1000.
The human TSPY (testis-specific protein, Y-linked) gene family (30-60 copies) is situated in the MSY (male-specific) region of the Y chromosome. Testis-specific expression indicates that the gene plays a role in spermatogenesis. Refined quantitative fluorescence PCR (polymerase chain reaction) was applied to evaluate the relative number of TSPY copies compared with AMELY/X (amelogenin gene, Y-linked) genes in 84 stratified infertile men and in 40 controls. A significantly higher number of TSPY copies was found in infertile men compared with the controls (P = 0.002). The diagnostic discrimination potential of the relative number of TSPY copies was evaluated by receiver operating characteristic curve analysis. TSPY/AMELY was unambiguously found to be powerful in the diagnostic separation of both the control samples and the infertile men, reaching a good level of specificity (0.642) and sensitivity (0.732) at a cut-off point of 0.46. The findings were supported by independently repeated studies of randomly selected positive samples and controls. Evaluation of the TSPY copy number offers a completely new diagnostic approach in relation to the genetic cause of male infertility. The possible effect of the copy number of TSPY genes on spermatogenesis may explain indiscrete pathological alterations of spermatid quality and quantity.  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