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   531篇
  免费   28篇
  国内免费   7篇
耳鼻咽喉   2篇
儿科学   1篇
妇产科学   4篇
基础医学   91篇
口腔科学   4篇
临床医学   39篇
内科学   157篇
皮肤病学   5篇
神经病学   88篇
特种医学   11篇
外科学   94篇
综合类   2篇
一般理论   1篇
预防医学   14篇
眼科学   5篇
药学   25篇
中国医学   2篇
肿瘤学   21篇
  2023年   4篇
  2022年   14篇
  2021年   31篇
  2020年   7篇
  2019年   9篇
  2018年   13篇
  2017年   13篇
  2016年   18篇
  2015年   21篇
  2014年   20篇
  2013年   21篇
  2012年   37篇
  2011年   37篇
  2010年   17篇
  2009年   14篇
  2008年   27篇
  2007年   26篇
  2006年   28篇
  2005年   32篇
  2004年   38篇
  2003年   22篇
  2002年   29篇
  2001年   4篇
  2000年   4篇
  1999年   2篇
  1998年   10篇
  1997年   8篇
  1995年   2篇
  1990年   3篇
  1989年   2篇
  1988年   2篇
  1985年   5篇
  1984年   3篇
  1983年   2篇
  1982年   2篇
  1981年   5篇
  1980年   2篇
  1979年   2篇
  1978年   4篇
  1977年   4篇
  1976年   1篇
  1975年   3篇
  1974年   2篇
  1973年   1篇
  1971年   1篇
  1970年   1篇
  1969年   3篇
  1968年   2篇
  1966年   1篇
  1943年   2篇
排序方式: 共有566条查询结果,搜索用时 31 毫秒
1.
OBJECTIVE: A relationship between brain atrophy and delta rhythmicity (1.5-4 Hz) has been previously explored in Alzheimer's disease (AD) subjects [Fernandez A, Arrazola J, Maestu F, Amo C, Gil-Gregorio P, Wienbruch C, Ortiz T. Correlations of hippocampal atrophy and focal low-frequency magnetic activity in Alzheimer disease: volumetric MR imaging-magnetoencephalographic study. Am J Neuroradiol. 2003 24(3):481-487]. In this study, we tested the hypothesis that such a relationship does exist not only in AD patients but also across the continuum of subjects with mild cognitive impairment (MCI) and AD. METHODS: Resting, eyes-closed EEG data were recorded in 34 MCI and 65 AD subjects. EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). EEG cortical sources were estimated by LORETA. Cortical EEG sources were correlated with MR-based measurements of lobar brain volume (white and gray matter). RESULTS: A negative correlation was observed between the frontal white matter and the amplitude of frontal delta sources (2-4 Hz) across MCI and AD subjects. CONCLUSIONS: These results confirmed for the first time the hypothesis that the sources of resting delta rhythms (2-4 Hz) are correlated with lobar brain volume across MCI and AD subjects. SIGNIFICANCE: The present findings support, at least at group level, the 'transition hypothesis' of brain structural and functional continuity between MCI and AD.  相似文献   
2.
Summary A recessive mutant allele, mef1-84, of a novel locus mapping on the left arm of chromosome I, between ade3 and ura1, 5 cM apart from lys5, confers temperature-sensitive growth and mating deficiency at the nonrestrictive temperatures for growth. Two other mutations suppress the phenotype conferred by mef1-84: sts1-1 suppresses the temperature-sensitive growth only, and smd1-35 suppresses both temperature-sensitive growth and mating deficiency.  相似文献   
3.
4.
In order to detect the subcellular localization of calcium in the myocardium of laboratory animals (rats and guinea-pigs) under the influence of 2'-(2-diethylaminoethoxy)-3-phenyl-propiophenone (etafenone, Baxacor) (4 mg, 20 mg and 100 mg/kg body weight) two ultracytochemical methods, with lead acetate and with potassium pyroantimonate, were used. In addition, X-ray microanalysis of myocardial fragments was performed. The correlation of ultrastructural, ultracytochemical and X-ray microanalytical findings provides direct evidence of the hypothesis that etafenone acts on myocardium as a so-called "calcium antagonist". The subcellular targets of etafenone action are mainly the sarcoplasmic reticulum and mitochondria. Etafenone modifies also the concentration of copper, zinc and selenium in myocardium. The effect of etaferone on myocardial calcium and oligoelements appears to be dose-dependent.  相似文献   
5.
PURPOSE: The idiotype (Id) of the immunoglobulin on a given B-cell malignancy is a clonal marker that can serve as a tumor-specific antigen. We developed a novel vaccine formulation by incorporating Id protein with liposomal lymphokine that was more potent than a prototype, carrier-conjugated Id protein vaccine in preclinical studies. In the present study, we evaluated the safety and immunogenicity of this vaccine in follicular lymphoma patients. EXPERIMENTAL DESIGN: Ten patients with advanced-stage follicular lymphoma were treated with five doses of this second generation vaccine after chemotherapy-induced clinical remission. All patients were evaluated for cellular and humoral immune responses. RESULTS: Autologous tumor and Id-specific type I cytokine responses were induced by vaccination in 10 and 9 patients, respectively. Antitumor immune responses were mediated by both CD4+ and CD8+ T cells, were human lymphocyte antigen class I and II associated, and persisted 18 months beyond the completion of vaccination. Specific anti-Id antibody responses were detected in four patients. After a median follow-up of 50 months, 6 of the 10 patients remain in continuous first complete remission. CONCLUSIONS: This first clinical report of a liposomal cancer vaccine demonstrates that liposomal delivery is safe, induces sustained tumor-specific CD4+ and CD8+ T-cell responses in lymphoma patients, and may serve as a model for vaccine development against other human cancers and infectious pathogens.  相似文献   
6.
Introduction: We followed patients with pulmonary arterial hypertension (PAH) receiving specific vasodilator therapy and tested for predictors of clinical outcome. Methods: Thirty‐two patients (mean age 39 ± 15 years, 22 women, diagnosed with pulmonary hypertension; PH): 29 with PAH and 3 patients with inoperable chronic thromboembolic PH received therapy with either bosentan, sildenafil, or both and were evaluated with clinical parameters, biomarkers (B‐type natriuretic peptide values), and echocardiography before receiving specific medication and every 3 months thereafter. A right heart catheterization was performed at baseline. A composite endpoint of death, worsening of functional class, or the need of a second vasodilator agent was used to define the clinical nonresponders. Results: Patients were followed for 14 months (7.5–21). The endpoint was reached by 15 patients: four patients died (two idiopathic PAH and two PAH in context of Eisenmenger syndrome), seven patients showed 1 functional class worsening, and four patients needed to be switched to combination therapy. Patients who remained clinically stable or improved had at baseline a better cardiac output with a less remodeled right ventricle (RV) and better functioning RV (all P < 0.05). A RV fractional area change (RVFAC) lower than 25.7% and a RV global strain value higher than ?13.4% predict with 87% sensitivity and 83% specificity (AUC 87.3%, P = 0.001) and 73% sensitivity and 91% specificity (AUC 84.2%, P = 0.003), respectively, patients who will deteriorate clinically under specific vasodilator therapy. A multivariate model showed RVFAC to be the only independent predictor of the endpoint with a HR of 0.87 (0.8–0.96), P = 0.007. Conclusions: Over an average period of 1 year, almost half of patients showed signs of clinical deterioration despite specific vasodilator therapy. Parameters of right ventricular morphology and function had prognostic value in these patients.  相似文献   
7.
Antibacterial activity of 1,1′-methylenedipyrazole (AM1), 1-hydroxymethylpyrazole (SAM1), 1,1′-methylenediimidazole (AM2), and 1-hydroxymethylimidazole (SAM2) has been tested against reference and clinical strains by both difusimetric and broth dilution methods. Overall, the minimal inhibitory concentrations of tested compounds ranged from 180 to 270?μg/ml, while the minimal bactericidal concentrations were between 360 and 720?μg/ml. Comparative assessment with phenol and formaldehyde shows that AM1, AM2, SAM1, and SAM2 have moderate to good antibacterial activity.  相似文献   
8.
BACKGROUND: The superior mesenteric artery (SMA) first approach was proposed recently as a new modification of the standard pancreaticoduodenectomy. Increasing evidence showed that a periadventiceal dissection of the SMA with early transection of the inflow during pancreaticoduodenec-tomy associates better early perioperative results, and setup the scene for long-term oncological benefits. The objectives of the current study are to compare the operative results and long-term oncological outcomes of SMA first approach pan-creaticoduodenectomy (SMA-PD) with standard pancreatico-duodenectomy (S-PD).DATA SOURCES: Electronic search of the PubMed/MEDLINE, EMBASE, Web of Science and Cochrane Library was performed until July 2015. We considered randomized controlled trials (RCTs) and non-randomized comparative studies (NRCSs) comparing SMA-PD with S-PD to be eligible if they included patients with periampullary cancers.RESULTS: A total of one RCT and thirteen NRCSs met the in-clusion criteria, involving 640 patients with SMA-PD and 514 patients with S-PD. The SMA-PD was associated with less in-traoperative bleeding, less blood transfusions and higher rate of associated venous resections. The pancreatic fistula and delayed gastric emptying had a significantly lower rate in the SMA-PD group. There were no differences between the two approaches regarding overall complications, major complica-tion rates and in-hospital mortality. There was no difference regarding R0 resection rate, and one-, two- or three-year over-all survival. The SMA-PD was associated with a lower local, hepatic and extrahepatic metastatic rate.CONCLUSIONS: The SMA-PD is associated with better perioperative outcomes, such as blood loss, transfusion re-quirements, pancreatic fistula, and delayed gastric emptying. Although the one-, two- or three-year overall survival rate is not superior, the SMA-PD has a lower local and metastatic re-currence rate.  相似文献   
9.
Secondary to the detection of a chronic anemia with a slightly increased Hb F level in a 7‐year-old boy carrying a hemoglobin (Hb) variant, we investigated the members of his family and found that they were related to the original case of Hb Calais. In the present study, we report the clinical and biological impacts of this Hb variant in various members of three generations of this family.  相似文献   
10.
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