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   7023篇
  免费   402篇
  国内免费   53篇
耳鼻咽喉   87篇
儿科学   194篇
妇产科学   67篇
基础医学   784篇
口腔科学   110篇
临床医学   402篇
内科学   2348篇
皮肤病学   64篇
神经病学   528篇
特种医学   189篇
外科学   1134篇
综合类   28篇
预防医学   184篇
眼科学   83篇
药学   437篇
中国医学   38篇
肿瘤学   801篇
  2023年   49篇
  2022年   103篇
  2021年   158篇
  2020年   117篇
  2019年   140篇
  2018年   165篇
  2017年   116篇
  2016年   153篇
  2015年   178篇
  2014年   241篇
  2013年   236篇
  2012年   409篇
  2011年   423篇
  2010年   226篇
  2009年   202篇
  2008年   296篇
  2007年   343篇
  2006年   290篇
  2005年   347篇
  2004年   328篇
  2003年   311篇
  2002年   285篇
  2001年   177篇
  2000年   208篇
  1999年   216篇
  1998年   84篇
  1997年   60篇
  1996年   62篇
  1995年   57篇
  1994年   44篇
  1993年   59篇
  1992年   128篇
  1991年   125篇
  1990年   117篇
  1989年   137篇
  1988年   113篇
  1987年   93篇
  1986年   93篇
  1985年   97篇
  1984年   57篇
  1983年   41篇
  1982年   23篇
  1979年   47篇
  1978年   22篇
  1975年   26篇
  1973年   25篇
  1972年   24篇
  1970年   27篇
  1969年   25篇
  1968年   24篇
排序方式: 共有7478条查询结果,搜索用时 0 毫秒
1.
Of 15 patients with primary aldosteronism, 7 had idiopathic adrenal hyperplasia (IHA) and 8 had aldosterone-producing adenoma (APA). In order to determine any renal problems involved in the treatment, the renal clearance of these patients was analyzed and the results compared with those obtained from 12 patients with essential hypertension. With water diuresis or under antidiuresis status, levels of urine volume, Cosm and CH2O in patients with APA were greater (p less than 0.05-p less than 0.001) than those of patients with essential hypertension, while the fractional tubular sodium delivery of the former patients was lower than that of the latter patients (p less than 0.001 or less than 0.05). A similar tendency was observed in clearance studies in patients with IHA, although to a lesser extent. Adrenal surgery for patients with APA normalized these values, but administration of trilostane (3 beta-hydrosteroid dehydrogenase inhibitor) to patients with IHA failed to improve these values. These results indicate that impaired urinary concentrating ability as well as reduced urinary diluting capability is a common feature of primary aldosteronism. Such impaired renal function was improved only in patients with APA after adrenal surgery.  相似文献   
2.
We present herein the rare case of a young man who was found to have a solitary tumor in the right upper lobe of his lung by a routine chest X-ray. The tumor was removed by thoracoscopic surgery, and pathological examinations confirmed the diagnosis of a primary lymphangioma of the lung. A brief review of the available literature on this extremely rare type of benign tumor follows the case report.  相似文献   
3.
 We describe a rare case of papillary carcinoma with extensive proliferation of stromal cells. The stromal cells were immunocytochemically positive for vimentin, α-smooth muscle actin and desmin, but negative for cytokeratin, epithelial membrane antigen, S-100, thyroglobulin and CD34. These results and the ultrastructure of the stromal cells, which exhibited the characteristics of both fibroblasts and smooth muscle cells, indicated an origin from myofibroblasts. We conclude that myofibroblastic proliferation may contribute to the stromal response in the slow growth of the papillary carcinoma. Received: 29 August 1996 / 26 May 1997  相似文献   
4.
Hepatocyte regeneration has been widely investigated, with the mitotic index and the incorporation of [3H]thymidine being used as regeneration markers. We focused on the induction of DNA replication enzymes, particularly DNA polymerases (pol) α, δ, and ε. Using rat models, we have shown that the activity of pol α in crude liver extract well represents the regenerating capacity of hepatocytes. Using pol α as an indicator, we analyzed liver regeneration in rat models under various conditions: obstructive jaundice, external or internal biliary drainage, and the obstruction of portal vein branches. It has been revealed that the ligation of the common bile duct alone induces a certain amount of hepatocyte proliferation. It was striking that external biliary drainage suppressed regeneration capacity in cholestatic rat liver after partial hepatectomy. The strong regeneration in nonligated lobes induced by portal branch ligation was similar to the liver regeneration seen after partial hepatectomy with respect to the induction of DNA polymerases. Taken together, the aspects of DNA replication, particularly the induction of DNA polymerases, may contribute to shedding new light on the regeneration of human liver. This work was supported in part by a Grant-in-Aid for General Scientific Research and for Cancer Research from the Ministry of Education, Science and Culture, Japan, and by grants from the Uehara Memorial Foundation  相似文献   
5.
The pulmonary lesions were studied in 24 autopsy cases of Japanese patients with AIDS. The major pathological findings were opportunistic infections, which were the major clinical symptoms in some patients. The pathogens identified were as follows; Pneumocystis carinii (PC) in 10, cytomegalovirus (CMV) in 14, atypical mycobacterium in 5, cryptococcus in 2, candida in 2, and nocardia in 1. PC pneumonia was prominent in 8 cases and was the cause of death. In such patients, the lung were heavy and appeared parenchymatous. Histological examination revealed numerous protozoa in the foamy material in the alveolar spaces, associated with swelling of the alveolar lining cells and edematous thickening of the alveolar septa. In some cases, only hyaline membrane formation was prominent without foamy material in the alveolar spaces. Immunostaining with anti-PC monoclonal antibody or in-situ hybridization with oligopeptide demonstrated pathogens in the hyaline membranes. Many cases with PC pneumonia had concomitant opportunistic infections such as CMV, Herpes simplex virus, and atypical mycobacterium. Extrapulmonary infection of PC was seen in only one case. CMV infection was found in 14 cases; 7 had innumerable inclusion bodies, and in some cases the lesions were most prominent around the bronchioles. Of the 5 cases of atypical mycobacterial infection, 2 were caused by M. kansaii (MK) and 3 by M. avium intracellulare (MAI). Both lesions of MK infection showed necrosis and cavitation. One of three cases of MAI infection showed cavitation. Around the cavitary lesions, numerous cytomegalic inclusion bodies were identified in the mesenchymal cells, which may have been the cause of necrosis and cavitation of the lesions. MAI infection was systemic and pronounced in the lymph nodes, spleen, and intestinal mucosa. Neoplastic lesions comprised 2 cases of Kaposi's sarcoma and 4 of extranodal non-Hodgkin lymphoma in other organs. Lung involvement was seen in only one case of Kaposi's sarcoma although very small in size. The lesion was situated along the pulmonary vein and appeared hemorrhagic macroscopically. Pulmonary lesions in AIDS are complicated, and many of opportunistic pathogens were identified in single patients.  相似文献   
6.
A precision device was developed for quantitative measurement of the active and passive forces of the horizontal muscles in several different types of strabismus. The device consists of a tension gauge for measuring isometric muscle tension (active force) and passive length-tension (passive force), and a circular-motion guide mechanism. In normal subjects, the active force showed nearly linear changes with the eye position, as was reported in past studies. A similar relationship between the active force and the eye position was observed also in strabismus patients in our study. Normal subjects showed a stronger force in the medial than the lateral rectus muscle. Among strabismus patients, those with normal retinal correspondence (NRC)-intermittent exotropia showed a force closest to that of the normal controls. However, the force of the lateral rectus muscle was significantly greater in those with constant exotropia than in the normal controls. The active force of the medial rectus muscle was significantly smaller in those with dual retinal correspondence (DRC)-intermittent exotropia and constant exotropia. Conversely, the active force of the medial rectus muscle was significantly greater in those with esotropia, compared with the normal group. As for the passive force, there was no significant difference between the temporal passive force and the nasal passive force in the normal and esotropic groups, but the temporal passive force was significantly greater in the esotropic group. The magnitude of the force was greater in both directions when traction was applied against the muscle having the stronger active force. These results suggest that the lateral rectus muscle force is relatively stronger in patients with DRC-intermittent exotropia due to a weakness of the medial rectus muscle force, and that the absolute strength of the lateral rectus muscle force is increased in patients with constant exotropia, but in NRC-intermittent exotropia the muscle forces are almost normal. Those with esotropia are considered to have an absolute increase in the medial rectus muscle force.  相似文献   
7.
We reported movement-related cortical potentials (MRCPs) in 11 patients with lesion of the dentate nucleus (Machado-Joseph disease (MJD) 7 cases, dentato-rubro-pallido-luysian atrophy (DRPLA)1, myoclonus epilepsy associated with ragged-red fibers (MERRF)1, dyssynergia cerebellaris myoclonica (DCM) 2), and compared with those of 7 cases of multiple system atrophy (MSA) who were postulated to have mild dentate lesions (striato-nigral degeneration 2 cases, Shy-Drager syndrome 2, sporadic olivo-ponto-cerebellar atrophy 3), and 7 control subjects without any neurological findings. Further we classified the diseases into the following two groups based on the lesion of the dentate nucleus. One was MJD group that had normal or slightly abnormal electroencephalogram (EEG), and the other was DN group (DRPLA, MERRF, DCM) that had markedly abnormal EEG. One of the main findings from this study was smaller slope of the Ns' in the MJD and DN group and normal slope of BP. There was no significant difference in the slope of Ns' between MJD patients and DN patients. This result shows EEG abnormalities have no influence on MRCP recordings. These results suggest that Ns' component may reflect the function in the cerebellar dentate nucleus, and that MRCP is a useful diagnostic method in patients with cerebellar ataxia.  相似文献   
8.
The cause of aplastic anemia associated with hepatitis (AAH) is as yet still unknown. There is a supposed relation to the immune mechanisms, however few reports have shown the effects of monocytes on the pathogenesis in the patients with AAH. We have reported a case of a 12-year-old boy with AAH related to cytomegaloviruses, and studied the hemopoietic progenitors. He showed pancytopenia and hypoplasia of the bone marrow on admission to our hospital. The culture studies showed that mononuclear cells (MNC) of the bone marrow produced few hemopoietic colonies in all cell lineages. However, the depletion of adherent cells from the MNC increased numbers of erythroid, neutrophil-macrophage and megakaryocyte colonies. Furthermore, the addition of adherent cells of the peripheral blood suppressed the colony formation in the aforementioned cell lineages by marrow MNC from which adherent cells, phagocytic cells and T-cells were abrogated. The results way suggest that monocytes play some soles in the pathogenesis of aplasia through inhibitor of hemopoiesis.  相似文献   
9.
Two elderly women complaining of intermittent claudication complicated with persistent sciatic artery are herein reported. A direct femoral arteriogram showed hypoplasty of the superficial femoral artery and an unnatural anatomical relationship between the distal superficial femoral artery and the proximal popliteal artery, thus suggesting the presence of persistent sciatic artery. The diagnosis of persistent sciatic artery was finally made based on the aortography findings including the iliac arterial system and computed tomography (CT) scan. Magnetic resonance imaging (MRI) was helpful to demonstrate the entire image of this anomaly in cases with non-thrombolized sciatic artery. These diagnostic methods were useful in designing the optimal surgical strategy. The first case with a gluteal pulsating mass underwent exclusion of the persistent sciatic artery including the aneurysm through a retroperitoneal approach with a combination of femorotibial bypass, while the second case with thrombosed persistent sciatic artery only underwent femoropopliteal bypass. To recognize such a rare lesion, awareness of the differential diagnosis is important, and to provide appropriate treatment, an accurate whole image including adequate angiography, a CT scan, and magnetic resonance imaging is necessary.  相似文献   
10.
β2-glycoprotein-I (β2GPI) is a phospholipid-binding plasma protein that consists of five homologous domains. Domain V is distinguished from others by bearing a positively charged lysine cluster and hydrophobic extra C-terminal loop. β2GPI has been known as a natural anticoagulant regulator. β2GPI exerts anticoagulant activity by inhibition of phospholipid-dependent coagulation reactions such as prothrombinase, tenase, and factor XII activation. It also binds factor XI and inhibits its activation. On the other hand, β2GPI inhibits anticoagulant activity of activated protein C. According to the data from knockout mice, β2GPI may contribute to thrombin generation in vivo. Phospholipid-bound β2GPI is one of the major target antigens for antiphospholipid antibodies present in patients with antiphospholipid syndrome (APS). Binding of pathogenic anti-β2GPI antibodies increases the affinity of β2GPI to the cell surface and disrupts the coagulation/fibrinolysis balance on the cell surface. These pathogenic antibodies activate endothelial cells via signal transduction events in the presence of β2GPI. Impaired fibrinolysis has been reported in patients with APS. Using a newly developed chromogenic assay, we demonstrated lower activity of intrinsic fibrinolysis in euglobulin fractions from APS patients. Addition of monoclonal anti-β2GPI antibodies with β2GPI also decreased fibrinolytic activity in this assay system. β2GPI is proteolytically cleaved by plasmin in domain V (nicked β2GPI) and becomes unable to bind to phospholipids, reducing antigenicity against antiphospholipid antibodies. This cleavage occurs in patients with increased fibrinolysis turnover. Nicked β2GPI binds to plasminogen and suppresses plasmin generation in the presence of fibrin, plasminogen, and tissue plasminogen activator (tPA). Thus, nicked β2GPI plays a role in the extrinsic fibrinolysis via a negative feedback pathway loop.  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