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   3548篇
  免费   137篇
  国内免费   19篇
耳鼻咽喉   10篇
儿科学   63篇
妇产科学   122篇
基础医学   489篇
口腔科学   154篇
临床医学   211篇
内科学   879篇
皮肤病学   17篇
神经病学   153篇
特种医学   87篇
外科学   752篇
综合类   9篇
预防医学   47篇
眼科学   51篇
药学   195篇
中国医学   8篇
肿瘤学   457篇
  2024年   3篇
  2023年   19篇
  2022年   36篇
  2021年   84篇
  2020年   28篇
  2019年   58篇
  2018年   79篇
  2017年   65篇
  2016年   79篇
  2015年   83篇
  2014年   120篇
  2013年   145篇
  2012年   224篇
  2011年   247篇
  2010年   162篇
  2009年   118篇
  2008年   235篇
  2007年   229篇
  2006年   224篇
  2005年   231篇
  2004年   252篇
  2003年   248篇
  2002年   212篇
  2001年   39篇
  2000年   35篇
  1999年   48篇
  1998年   41篇
  1997年   28篇
  1996年   43篇
  1995年   34篇
  1994年   35篇
  1993年   19篇
  1992年   16篇
  1991年   17篇
  1990年   19篇
  1989年   23篇
  1988年   21篇
  1987年   12篇
  1986年   11篇
  1985年   8篇
  1984年   9篇
  1983年   10篇
  1982年   11篇
  1981年   6篇
  1980年   10篇
  1978年   3篇
  1975年   3篇
  1973年   4篇
  1969年   6篇
  1966年   3篇
排序方式: 共有3704条查询结果,搜索用时 734 毫秒
61.
Soluble Fas ligand and atherosclerosis in hypertensive patients   总被引:2,自引:0,他引:2  
BACKGROUND : The Fas-Fas ligand (FasL) system is involved in apoptosis in many types of cells. Recently, the expression of FasL on endothelial cells was reported. FasL is cleaved by a metalloproteinase and released in serum as soluble FasL (sFasL). Vasoactive substances, including metalloproteinase, are modulated by endothelial dysfunction. Advanced atherosclerosis and impaired endothelial function are seen in hypertensive patients. The inflammatory response has an important role in the development of atherosclerosis, whereas C-reactive protein (CRP) is associated with the presence and severity of atherosclerosis. OBJECTIVE : To measure the intima-media thickness of the common carotid artery and evaluate the relationship between atherosclerosis and serum sFasL concentrations in hypertensive patients. PATIENTS AND MAIN OUTCOME MEASURES : Forty-seven patients with hypertension participated in the study. The intima-media thickness of the common carotid artery was evaluated by ultrasound imaging. Serum concentrations of sFasL were measured by enzyme-linked immunosorbent assay. RESULTS : Intima-media thickness correlated positively with age (r = 0.362, P = 0.012) and sFasL concentrations (r =0.332, P = 0.022), and negatively with creatinine clearance (r = -0.399, P = 0.0055). A general linear model analysis with atherosclerotic risk factors and sFasL revealed that age, sFasL, high-density lipoprotein-cholesterol and systolic blood pressure were significantly associated with intima-media thickness. Furthermore, we demonstrated that serum sFasL is directly associated with CRP concentration (r = 0.316, P = 0.030). CONCLUSIONS : These results indicated that serum sFasL concentration is associated with atherosclerosis and inflammatory disease, in patients with hypertension.  相似文献   
62.
63.
Ceramide has been confirmed to be a signal mediator of apoptosis that is induced by tumor necrosis factor-alpha (TNF-alpha). It has also been reported that ceramide may induce insulin resistance as well as TNF-alpha. We investigated the effect of ceramide on insulin signaling pathways, such as insulin receptor (IR) beta-subunit, insulin receptor substrate 1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), and protein kinase Czeta (PKCzeta) in rat adipocytes. We examined insulin-stimulated [(3)H]2-deoxyglucose (2-DOG) uptake in rat adipocytes pretreated with N-hexanoylsphingosine (C(6)-ceramide, 10 to 30 micromol/L). Insulin-induced 2-DOG uptake was significantly reduced by C(6)-ceramide pretreatment. We also examined the effect of various concentrations of C(6)-ceramide pretreatment on insulin-induced autophosphorylation of the IR beta-subunit, tyrosine phosphorylation of IRS-1, enzyme activity of PI3K, and membrane-associated PKCzeta immunoreactivity. Pretreatment with C(6)-ceramide significantly reduced autophosphorylation of the IR beta-subunit, tyrosine phosphorylation of IRS-1, and enzyme activity of PI3K. Moreover, membrane-associated PKCzeta immunoreactivity and immunoprecipitable PKCzeta enzyme activity, downstream of PI3K, were significantly suppressed by C(6)-ceramide pretreatment. These results suggest that ceramide may induce insulin resistance via the suppression of IRS-1-PI3K signaling, and subsequent activation of PKCzeta.  相似文献   
64.
Severe hepatitis with an indistinct etiology manifested in a 16-year-old boy who had no particular history. The histological features of the liver and clinical course of the patient were similar to those of patients with autoimmune hepatitis characterized by interface hepatitis and severe lobular inflammation of the liver and recurrent exacerbations of hepatitis. We administered intravenous glycyrrhizin preparation daily or three times a week combined with the oral administration of ursodeoxycholic acid daily throughout the term after the initial onset of disease for the control of disease activity. The normalization of the concentration of alanine aminotransferase in serum was achieved in response to the therapy during the course. The serum concentration of immunoglobulins of the patient gradually decreased from the onset of the disease to an unacceptable level without globulin preparation during the following period of 17 months. Immunological tests revealed impairment of immunoglobulin production bythe B cell population of the patient, which led to the diagnosis of the patient as common variable immunodeficiency (CVID). The patient, with improved liver histology after 27 months from the onset of disease, benefited from the current combination therapy without severe infection through the avoidance of overimmunosuppression. CVID is defined as a heterogeneous syndrome characterized by various degrees of hypogammaglobulinemia without any specific predisposing causes, frequently associated with autoimmunity. Diagnostic criteria and therapeutic options of persistent hepatitis with CVID are to be established, as discussed in the current report.  相似文献   
65.
We present a case of a synchronous primary lung cancer adjacent to a hamartoma. In a 48-year-old man, a nodular shadow was found in the right middle lung field in 1990, and had grown slowly for 10 years. Another mass shadow was detected in the right upper lung field in 2000. The patient was admitted to our hospital for further examination of these abnormal shadows. Bronchoscopic examination revealed, in the right upper lobe, a poorly differentiated adenocarcinoma of clinical stage IIIB. Neoadjuvant chemotherapy followed by pneumonectomy was performed. The microscopic findings for the tumor resected from the right S2 showed poorly differentiated adenocarcinoma and those for the other, in the right S3, showed chondromatous hamartoma. Some 50 reports of lung cancer in parents with a chondromatous hamartoma have appeared in the literature. Most of these cases have some common features as follows: 1) men past middle age, 2) adenocarcinoma, and 3) lung cancer and chondromatous hamartoma present in the same lobe. The present case had all of these features, and may assist in the understanding of the process of development of lung cancer adjacent to a hamartoma.  相似文献   
66.
Reticulated platelets (RP) and large platelets (LP) were measured by an automated hematology analyzer (modified R-2000) in 287 healthy volunteers and 131 patients with thrombocytopenia or thrombocytosis. RP was significantly higher in patients with idiopathic thrombocytopenic purpura (ITP), especially in active phase, while RP was markedly lower in patients with essential thrombocytosis (ET) or chronic myelocytic leukemia (CML). LP was significantly higher in patients with ITP, especially in active phase, while LP was markedly lower in patients with aplastic anemia (AA), ET, or CML. In ITP, RP and LP were significantly higher in patients positive for anti-glycoprotein (Gp) IIb/IIIa antibody. RP and LP were poorly correlated with platelet-associated IgG (PAIgG). RP and LP were poorly correlated with plasma thrombopoietin levels, and negatively correlated with platelet count. These results show that RP reflects the pathology of thrombocytopenic disorders, and that measurement of RP is useful for the differential diagnosis and analysis of platelet kinetics.  相似文献   
67.
We studied MDS-associated inhibitory activity, which inhibited colony formation in vitro of granulocyte-macrophage progenitors (CFU-GM). Macrophages obtained from MDS bone marrow mononuclear cells (BM-MNC) when pretreated with granulocyte-macrophage colony stimulating factor (GM-CSF) suppressed the growth of normal CFU-GM. These macrophages were designated as 'MDS-derived inhibitory macrophages'. Media conditioned by MDS-derived inhibitory macrophages (MDS-CM) also suppressed the growth of normal CFU-GM. In the MDS-CM, high levels of prostaglandin E2 (PGE2) and ferritin were found. However, MDS-CM did not contain detectable levels of tumour necrosis factor (TNF) or gamma-interferon (gamma-IFN). Antiserum against human placental ferritin and/or against PGE2 blocked the haemopoietic inhibitory activity to some extent. These results suggest that inhibitory macrophages may be responsible for the suppression of granulopoiesis in patients with MDS and that the suppression may be mediated by soluble factors including PGE2 and ferritin.  相似文献   
68.
A 30-year-old woman was admitted because of persistent and severe hemoptysis in November 2005. She had been given a diagnosis of interstitial pneumonia (IP) and pulmonary aspergilloma in 2001, and she was treated with oral prednisolone and itraconazole. However she had persistent and intractable hemoptysis. Multi-detector row computed tomography (MDCT) revealed that hemoptysis from the right upper lobe did not originate in bronchial arteries, but the abnormal branches of the right subclavian artery. Surgery was not performed because of her pulmonary function, but she was successfully treated by non-bronchial arterial coil embolization. At 10 months after the embolization, hemoptysis has not recurred. MDCT was very useful for diagnosing the cause of hemoptysis and selective nonbronchial arterial coil embolization might be helpful in treating intractable or refractory hemoptysis.  相似文献   
69.
70.
The effect of beta-blockade in dilated cardiomyopathy was studied by a questionnaire survey. Thirty-three cases were monitored in whom metoprolol (22 patients, 35.9 ± 20.4 mg, mean ± SD), propranolol (four patients, 26.3 ± 7.5 mg), or other beta-blockers (seven patients) were administered. Four patients died, but no direct relationship was found between administration of beta-blocker and death. The NYHA functional class improved significantly. The mean heart rate decreased from 96/min to 77/min (P < 0.01).=" the=" mean=" cardiothoracic=" ratio=" decreased=" from=" 55.6%=" to=" 52.1%=">P < 0.01).=" the=" mean=" ejection=" fraction=" of=" the=" left=" ventricle=" measured=" by=" echocardiogram=" increased=" from=" 30.4%=" to=" 36.9%=">P < 0.01).=" exercise=" tolerance=" in=" the=" treadmill=" test=" improved=" significantly.=" there=" was=" no=" change=" in=" blood=" pressure,=" nor=" were=" there=" arrhythmias=" seen=" on=" holter=" electrocardiograms.=" in=" two=" patients,=" congestive=" heart=" failure=" deteriorated=" after=" administration=" of=" beta-blockers.=" it=" is=" concluded=" that=" beta-adrenergic=" blockade=" has=" a=" beneficial=" effect=" in=" most=" of=" the=" patients=" with=" dilated=">This work was supported in part by a research grant from the Ministry of Health and Welfare and by a grant-in-aid for scientific research on priority areas and for general scientific research from the Ministry of Education, Science, and Culture, Japan, and Kanazawa Research Fund.  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