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   5408篇
  免费   242篇
  国内免费   20篇
耳鼻咽喉   70篇
儿科学   85篇
妇产科学   77篇
基础医学   603篇
口腔科学   154篇
临床医学   321篇
内科学   1377篇
皮肤病学   85篇
神经病学   210篇
特种医学   287篇
外科学   1123篇
综合类   12篇
一般理论   1篇
预防医学   102篇
眼科学   49篇
药学   375篇
中国医学   14篇
肿瘤学   725篇
  2023年   25篇
  2022年   54篇
  2021年   99篇
  2020年   73篇
  2019年   78篇
  2018年   103篇
  2017年   87篇
  2016年   94篇
  2015年   110篇
  2014年   142篇
  2013年   166篇
  2012年   274篇
  2011年   298篇
  2010年   159篇
  2009年   148篇
  2008年   267篇
  2007年   284篇
  2006年   247篇
  2005年   277篇
  2004年   274篇
  2003年   305篇
  2002年   285篇
  2001年   193篇
  2000年   206篇
  1999年   153篇
  1998年   83篇
  1997年   54篇
  1996年   41篇
  1995年   51篇
  1994年   54篇
  1993年   30篇
  1992年   89篇
  1991年   108篇
  1990年   80篇
  1989年   66篇
  1988年   57篇
  1987年   67篇
  1986年   56篇
  1985年   48篇
  1984年   41篇
  1983年   26篇
  1979年   24篇
  1978年   30篇
  1973年   20篇
  1972年   22篇
  1970年   21篇
  1969年   29篇
  1968年   21篇
  1967年   18篇
  1966年   16篇
排序方式: 共有5670条查询结果,搜索用时 31 毫秒
11.
Oxidative stress is implicated in the pathogenesis of various cardiovascular diseases. We have shown that in Wistar rats with a suprarenal aortic constriction (AC), pressure overload-induced transient perivascular inflammation (monocyte chemoattractant protein-1 [MCP-1] induction and macrophage accumulation) in the early phase is the determinant of reactive myocardial fibrosis and resultant diastolic dysfunction in the late phase. Thus, we investigated the role of reactive oxygen species production in cardiac remodeling in AC rats. Superoxide production and the footprint of lipid peroxidation were assessed using dihydroethidium staining and immunohistostaining against 4-hydroxy-2-nonenal (4-HNE), respectively. In sham rats, dihydroethidium and 4-HNE signals were scarcely found in the heart. At day 3, AC rats showed dihydroethidium signals mainly in the intramyocardial arterial wall, whereas modest 4-HNE staining was observed diffusely in the myocardium. These signals declined to lower levels by day 14 despite sustained hypertension. Chronic administration of a subdepressor dose of an angiotensin II type 1 receptor blocker candesartan reduced the pressure overload-induced dihydroethidium and 4-HNE signals at day 3. Moreover, candesartan decreased MCP-1 induction and macrophage infiltration at day 3 and prevented myocardial fibrosis at day 14, without affecting left ventricle and myocyte hypertrophy. In conclusion, acute pressure overload induced self-limited superoxide production mainly in the vascular wall. The reactive oxygen species production would contribute to the perivascular inflammation and subsequent myocardial fibrosis. Angiotensin II was suggested to have a pressure-independent effect on the reactive oxygen species production.  相似文献   
12.
The surgical approach to ischemic mitral regurgitation with concomitant inferior left ventricular aneurysm remains uncertain in terms of the indication for operation and the short-and long-term outcomes. We performed concomitant mitral valve repair, left ventricular reconstruction, and aortic valve replacement on a 71-year-old male with severe ischemic mitral regurgitation, inferior left ventricular aneurysm, and degenerative aortic regurgitation. Postoperative status was in New York Heart Association functional class I without mitral regurgitation 8 months after operation. We discuss, and review the procedures reported in the literature.  相似文献   
13.
14.
There is a growing body of evidence that the cytokine, tumor necrosis factor-α (TNF-ga), plays an important role in the development of hepatic ischemia/reperfusion injury. We found that the immunosuppressants, cyclosporine-A (CsA), azathioprine, and FK506, have protective effects on such injury. The purpose of the present study was to elucidate mechanisms involved in these beneficial effects of the immunosuppressant, CsA, on liver injury following cold preservation and transplantation, with special reference to the suppression of TNF-α release. Rat livers were stored in Euro-Collins solution (EC) at 4°C for 6h and orthotopically transplanted. The animals allotted to two groups: group A (untreated controls) and group B (CsA pretreatment of recipients). CsA (10 mg/kg, p.o.) was given for 3 consecutive days preoperatively. CsA pretreatment of the recipients significantly improved the 2-week survival rate (0/6 for group A, 3/6 for group B;P<0.05) and this was associated with a significant decrease in serum TNF-α levels 2h posttransplantation (group A, 69.8±15.7 pg/ml; group B, 22.8±6.8; mean±SEM;n=12 each;P<0.05) and amelioration of sinusoidal endothelial injury, assessed by electron microscopy. Plasma endotoxin levels following reperfusion of the grafts were not altered by the CsA therapy. Morphologically, CsA pretreatment of the recipients did not alter activation of Kupffer cells. CsA pretreatment of the recipient aids in preventing cold preservation/reperfusion injury of the liver graft, possibly by modulating effects of TNF-α.  相似文献   
15.
OBJECTIVE: The aim of this investigation was to establish the association between left-sided gallbladders and right-sided round ligaments. SUMMARY BACKGROUND DATA: The left-sided gallbladder is a rare anomaly and has been classified into two types: 1) gallbladder migration to the left side and 2) development of a second gallbladder with atrophy of the original one. Recently, left-sided gallbladders were reported to be associated with right-sided round ligaments. METHODS: The authors reviewed 3 patients treated in their departments and 15 patients reported in the literature diagnosed as having left-sided gallbladders accompanied by right-sided round ligaments. RESULTS: Although the gallbladders of all 18 patients were located at the normal site, they were diagnosed as being left sided because of the right-sided round ligaments. This anomaly was accompanied by abnormal intrahepatic portal venous branching, which could be classified into two types. In eight patients, the first branch of the portal vein ran to the posterior segment and then the portal vein formed a trunk of the left and right anterior portal veins. The latter portal vein formed the umbilical portion and finally joined the right-sided round ligament (trifurcation type). In five, the portal vein diverged normally to form the left and right portal veins, then the latter branched to form the anterior and posterior segments, and finally the anterior branch joined the round ligament (bifurcation type). In the other five, the branching type could not be determined. CONCLUSIONS: A right-sided round ligament causes a gallbladder at the normal site to be located on the left side. This anomaly should not be diagnosed as a left-sided gallbladder but as a right-sided round ligament. Recognition of this anomaly clinically is important when performing hepatectomy, because it is always associated with abnormal intrahepatic portal venous branching.  相似文献   
16.
To differentiate focal nodular hyperplasia (FNH) from other hepatic tumors, especially hepatocellular carcinoma, we evaluated the hemodynamics of histologically proved FNH in three patients, two by arterial angio-CT and one by microangiography of the resected specimen. These studies demonstrated the centrifugal blood supply of FNH (early filling of central tumor vessels radiating to periphery, and lobulated tumor stains with central low density area in the late phase), which could not be demonstrated by dynamic CT or hepatic angiography. Arterial angio-CT is useful as a further study, when differential diagnosis of FNH is uncertain by other imaging techniques.  相似文献   
17.
Chemiluminescence (CL) analysis of monocytes and polymorphonuclear cells (PMNs) was performed on 13 patients with Crohn's disease (CD) and 10 healthy volunteers. The percentages of monocyte populations in mononuclear cells obtained from the patients with CD were greater than those from the healthy volunteers, but the numbers of PMNs were not different between the two groups. The peak level of phorbol myristate acetate (PMA)-induced CL activity generated by diluted whole blood from the patients with CD was more significantly elevated than that from the healthy volunteers, whereas the peak levels of opsonized zymosan-induced CL activity did not differ between the two groups. In monocytes, the peak levels of both PMA- and opsonized zymosan-induced CL activity were significantly higher in the patients with CD than in the healthy volunteers. CL in PMNs, however, showed no significant difference between CD and controls. It is suggested that monocytes of CD have a large capacity to generate active oxygen species. The present study suggests that excessive active oxygen species released by monocytes and perhaps macrophages may play an important role in formation of the intestinal lesions in CD.This work was supported by the Grant of Tokuteishitsukan from the Japanese Ministry of Welfare and Health.  相似文献   
18.
The promoting effect of cyclic monoterpenes, 1% limonene (CAS 5989-27-5) and 1% cineole (CAS 470-82-6), on percutaneous absorption of nonsteroidal anti-inflammatory drugs was investigated in the rats. Compared with 1% laurocapram, drug absorption from the gel ointments was significantly more enhanced by addition of 1% limonene, while without any enhancer only ibuprofen penetrated across the skin in the limited amount. When using formulation with propylene glycol or 50% propylene glycolethanol solution, instead of carboxyvinyl polymer gel, percutaneous absorption significantly decreased and neither limonene nor cineole or laurocapram were capale to promote percutaneous absorption of flufenamic acid to sufficient serum level. Cineole and limonene were also evaluated in permeation experiments in vitro. Enhancement ability of limonene in the gel oinment was approximately 5 times higher comparing with enhancement ratio of cineole, while in 100% propylene glycol enhancement ability of both cyclic monoterpenes was equal. Good correlation was observed between in vivo and in vitro experiments. Evaluation of solubility proved that in the gel ointment simulated as water-ethanol solution were relatively best condition for percutaneous absorption of flufenamic acid when comparing with propylene glycol or 50% propylene glycol-ethanol solution.  相似文献   
19.
To elucidate the clinical characteristics of pulmonary edema in unstable angina, 120 patients with unstable angina who admitted to the hospital within 6 hours after the onset of chest pain were studied. The criteria for the diagnosis of pulmonary edema included interstitial pulmonary edema and diffuse alveolar edema. Pulmonary edema was present in 24 patients. In these patients, the duration of chest pain was relatively longer, and the incidences of diabetes mellitus, emergency coronary revascularization and multiple-vessel coronary artery disease were higher than in those without pulmonary edema. In addition, in-hospital mortality rate in patients with pulmonary edema was higher than in those without it (21 vs 1%, p < 0.001), which is probably due to a large area of myocardial ischemia. For these patients, therefore, early diagnosis and appropriate therapy to save viable segments of the myocardium are mandatory.  相似文献   
20.
The authors report six cases of non-Hodgkin's lymphoma (NHL) (3B-cell type, one T-cell type, one non-T non-B cell type, one unclassified type) occurring subsequently to autoimmune diseases. The patients were females aged 43 to 70 (median 61). Rheumatoid arthritis was most frequent as the preceding autoimmune disease, and the intervals from the onset of an autoimmune disease to that of NHL were 10 to 36 years (median 20). Polyclonal hypergammaglobulinemia was seen in 4 cases, lymphocytopenia in 3 cases, and conversion to negative PPD reaction in 2 cases. Only one patient had been given corticosteroids, and immunosuppressive agents may not contribute much to the development of lymphoma in patients with autoimmune diseases.  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