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   4017篇
  免费   162篇
  国内免费   29篇
耳鼻咽喉   41篇
儿科学   53篇
妇产科学   34篇
基础医学   582篇
口腔科学   62篇
临床医学   205篇
内科学   1224篇
皮肤病学   33篇
神经病学   383篇
特种医学   104篇
外科学   625篇
综合类   15篇
预防医学   84篇
眼科学   77篇
药学   235篇
中国医学   30篇
肿瘤学   421篇
  2023年   20篇
  2022年   44篇
  2021年   52篇
  2020年   45篇
  2019年   68篇
  2018年   82篇
  2017年   72篇
  2016年   74篇
  2015年   74篇
  2014年   112篇
  2013年   143篇
  2012年   244篇
  2011年   254篇
  2010年   142篇
  2009年   104篇
  2008年   250篇
  2007年   319篇
  2006年   255篇
  2005年   270篇
  2004年   290篇
  2003年   224篇
  2002年   212篇
  2001年   53篇
  2000年   42篇
  1999年   55篇
  1998年   62篇
  1997年   41篇
  1996年   40篇
  1995年   36篇
  1994年   49篇
  1993年   43篇
  1992年   35篇
  1991年   41篇
  1990年   33篇
  1989年   31篇
  1988年   22篇
  1987年   21篇
  1986年   14篇
  1985年   19篇
  1984年   21篇
  1983年   16篇
  1982年   19篇
  1981年   15篇
  1980年   17篇
  1979年   18篇
  1978年   20篇
  1975年   12篇
  1974年   12篇
  1973年   10篇
  1972年   13篇
排序方式: 共有4208条查询结果,搜索用时 31 毫秒
71.
ABSTRACT— Hepatic venograms made in 40 authentic cases of idiopathic portal hypertension (Banti's syndrome) were compared with 13 normal venograms and venograms obtained in 88 cases of cirrhosis, and analyzed in the light of the pathological changes seen in 16 postmortem liver specimens. There were frequent anastomoses between hepatic vein radicles, approximation of middle-size branches to the liver surface, reduction in the angles between the main hepatic vein and its tributaries, and difficulty in opacifying portal vein branches in wedged retrograde portography. These angiographic alterations were corroborated by gross pathological findings which comprised displacement of middle-size hepatic vein branches closer to the liver surface and their approximation among themselves, and seem to be accounted for by the disappearance of liver parenchyma secondary to the peripheral portal circulatory failure.  相似文献   
72.
We assessed the effects of angiotensin-converting enzyme (ACE) inhibition on changes in the myocardial intracellular creatine kinase (CK) system in relation to left ventricular (LV) remodeling and function in heart failure after myocardial infarction (MI) in rats. We compared the findings at 4 weeks after MI to those at 12 weeks after MI. LV weight and chamber size were significantly increased and percent fractional shortening (%FS) was decreased in untreated MI rats compared with normal control animals both at 4 and 12 weeks after MI. Animals with MI and treated with the ACE inhibitor temocapril showed significantly reduced LV weight and chamber size and increased %FS compared with untreated MI rats at 12 weeks after MI, but not at 4 weeks after MI. At 4 weeks after MI, no significant changes were found in the total creatine and relative distribution of each CK isoenzyme in either the temocapril-treated or untreated animals with MI compared with the normal controls. In contrast, at 12 weeks after MI, untreated MI rats showed significant reductions in the total creatine and mitochondrial and MM-CK fractions and increases in the MB- and BB-CK fractions compared with the controls. The alterations in the mitochondrial and MB-CK fractions were significantly attenuated after 12 weeks of ACE inhibition. Thus, LV myocardial energy metabolism is progressively impaired and its alteration is not related to the magnitude of geometric changes and LV dysfunction after MI. Most of the beneficial effects of ACE inhibition were observed at 12 weeks after MI. Our results may provide an insight into the therapeutic strategy of ACE inhibition in chronic heart failure after MI.  相似文献   
73.
A 64-year-old man was admitted due to hypokalemia-related myopathy. He was heavy drinker. He felt the stress of alcohol withdrawal during his hospitalization. The patient suffered a cardiopulmonary arrest lasting approximately 5 minutes on the fifth hospital day. One day later, ST-segment elevation was observed in leads I, aV(L), and V(2-6). Emergent cardiac catheterization was performed for suspicion of acute myocardial infarction. Normal coronary arteries with anterior akinesis of the left ventricle were revealed during the procedure. The present case may be an atypical form of "Takotsubo cardiomyopathy" in which the left ventricular contraction is due to focal anterior wall motion abnormalities.  相似文献   
74.
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   
75.
Clinical Rheumatology - This study aimed to evaluate the prevalence of, and the factors associated with, frailty in Japanese patients with rheumatoid arthritis (RA). Patients with RA enrolled in...  相似文献   
76.
Blood levels of inflammatory-related cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, are elevated in patients with alcoholic liver diseases. We investigated the effects of these cytokines and ethanol on the expression of hepatic asialoglycoprotein receptors (AGPRs) in a human hepatoblastoma cell line, HepG2. An [125I]-asialo-orosomucoid binding assay showed significant increases in surface AGPR numbers in HepG2 cells by treatment with IL-1β, IL-6, and TNF-α, to levels which were approximately 130% of the values in untreated control cells. However, the enhanced AGPR numbers induced by treatment with these cytokines were markedly suppressed, to 70%–80% of the number in the untreated cells, by treatment with ethanol. Immunological detection of AGPR with a specific antibody demonstrated that the modulation of surface AGPR numbers was correlated with the cellular expression levels of AGPR. These results suggest that, although IL-1β, IL-6, and TNF-α stimulate the synthesis of hepatic AGPR, ethanol suppresses the expression of AGPR augmented by these cytokines. This leads to an increase in serum asialo-orosomucoid levels caused by the disordered catabolism mediated by AGPR in patients with alcoholic liver disease. (Received Dec. 5, 1997; accepted May 22, 1998)  相似文献   
77.
Granulocyte elastase released from activatedleukocytes plays an important role in leukocyteinfiltration. Since activated leukocytes have been shownto be involved in the pathogenesis of gastric mucosal lesion formation induced by nonsteroidalantiinflammatory drugs, inhibition of granulocyteelastase release from activated leukocytes may be usefulin the prevention of these lesions. Rebamipide, a novel antiulcer agent, inhibited granulocyte elastaserelease from activated neutrophils in vitro. Rebamipideand ONO-5046, a granulocyte elastase inhibitor, markedlyinhibited gastric mucosal lesion formation in rats. Gastric myeloperoxidase activity wassignificantly increased 3 hr after indomethacinadministration. This increase was significantlyinhibited by rebamipide and ONO-5046. Cimetidine did notinhibit granulocyte elastase release from activatedneutrophils. Although cimetidine markedly prevented theindomethacin-induced gastric mucosal lesion formation,it did not reduce the gastric myeloperoxidase activity. Therefore, unlike cimetidine, rebamipide mayprevent indomethacin-induced gastric mucosal lesionformation by inhibiting neutrophil activation.  相似文献   
78.
The purpose of this study was to investigate whether an association exists between the promoter region of the prostacyclin synthase gene and essential hypertension (EH). Using the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) method, we discovered a novel single nucleotide polymorphism (SNP), T-192G, in the 5'-flanking region. We performed an association study using the SNP in 200 patients and 200 controls. The allele frequency distribution in the two groups was not significantly different. Thus, this SNP in the PGIS gene is not associated with EH.  相似文献   
79.
We have recently found that soluble form of receptor for advanced glycation end products (sRAGE) levels are positively associated with inflammatory biomarkers and the presence of coronary artery disease (CAD) in type 2 diabetic patients. Since advanced glycation end products (AGEs) up-regulate RAGE expression and endogenous sRAGE could be generated from the cleavage of cell surface RAGE, it is conceivable that sRAGE is positively associated with circulating AGEs levels in diabetes. In this study, we examined whether sRAGE were correlated to circulating levels of AGEs and soluble forms of vascular cell adhesion molecule-1 (sVCAM-1) and intercellular adhesion molecule-1 (sICAM-1) in patients with type 2 diabetes. Eighty-two Japanese type 2 diabetic patients underwent a complete history and physical examination, determination of blood chemistries, sRAGE, AGEs, sVCAM-1 and sICAM-1. Multiple regression analysis revealed that serum levels of AGEs and sVCAM-1 were independently correlated with sRAGE. This study demonstrated that serum levels of sRAGE were positively associated with circulating AGEs and sVCAM-1 levels in type 2 diabetic patients. Our present observations suggest sRAGE level may be elevated in response to circulating AGEs, thus being a novel marker of vascular injury in patients with type 2 diabetes.  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