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   52897篇
  免费   2546篇
  国内免费   409篇
耳鼻咽喉   581篇
儿科学   997篇
妇产科学   1438篇
基础医学   6452篇
口腔科学   2475篇
临床医学   4125篇
内科学   14196篇
皮肤病学   1144篇
神经病学   4552篇
特种医学   1352篇
外科学   7677篇
综合类   210篇
一般理论   12篇
预防医学   3276篇
眼科学   866篇
药学   3028篇
中国医学   195篇
肿瘤学   3276篇
  2024年   49篇
  2023年   419篇
  2022年   954篇
  2021年   1798篇
  2020年   992篇
  2019年   1403篇
  2018年   1885篇
  2017年   1243篇
  2016年   1362篇
  2015年   1600篇
  2014年   2157篇
  2013年   2773篇
  2012年   4276篇
  2011年   4279篇
  2010年   2354篇
  2009年   2054篇
  2008年   3542篇
  2007年   3608篇
  2006年   3323篇
  2005年   3253篇
  2004年   2897篇
  2003年   2584篇
  2002年   2290篇
  2001年   401篇
  2000年   306篇
  1999年   412篇
  1998年   399篇
  1997年   343篇
  1996年   305篇
  1995年   304篇
  1994年   233篇
  1993年   179篇
  1992年   180篇
  1991年   143篇
  1990年   130篇
  1989年   114篇
  1988年   98篇
  1987年   78篇
  1986年   88篇
  1985年   87篇
  1984年   90篇
  1983年   76篇
  1982年   100篇
  1981年   68篇
  1980年   85篇
  1979年   55篇
  1978年   51篇
  1977年   45篇
  1976年   40篇
  1974年   45篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Gastric mucormycosis involvement is a rare condition that usually occurs in inmunocompromised patients and frequently has a fatal outcome. We report the case of a 73‐year‐old woman admitted to the intensive care unit with severe bleeding after an acute pulmonary disease. Upper endoscopy disclosed wide and deep necrotic ulcers in the body and fundus of the stomach and greenish exudates with the antrum and the duodenum undamaged. Autopsy revealed an invasive mucormycosis and a severe atheromatosis. Several predisposing factors for mucormycosis infection have been reported until now. We postulate that ischemic gastritis could be a predisposing factor for colonization of zygomycete.  相似文献   
83.
84.
85.
1. The haemodynamic effects of calcium antagonists could depend at least in part on the activity of vasoactive prostanoids. 2. We set out to study the effect of the cyclo-oxygenase inhibitor ibuprofen, 400 mg three times daily for 3 days, by a randomised cross-over study vs placebo in 12 mild to moderate essential hypertensive patients who had been treated for 1 month with amlodipine. 3. Blood pressure, heart rate and vascular resistances in the upper limb (Doppler ultrasound) were measured. Plasma renin activity and urinary aldosterone, as well as indices of renal function, were evaluated. Urinary 2,3-dinor-6-keto-PGF1 alpha and 2,3-dinor-TXB2, as well as 6-keto-PGF1 alpha and TXB2, were measured as indices of systemic and renal PGI2 and TXA2 synthesis. 4. Amlodipine normalised blood pressure and reduced upper limb vascular resistances; it did not affect urinary prostanoid excretion. Short-term combined administration of ibuprofen resulted in, by comparison with placebo, inhibition of systemic PGI2 (-80.5 ng 24 h-1, 95% CI -99.2, -61.4; P < 0.001) and TXA2 (-216.1 ng 24 h-1, 95% CI -276.5, -155.8; P < 0.001), together with an increase in systolic (+7.8 mm Hg, 95% CI +3.1, +12.3; P < 0.01) and diastolic (+3.9 mm Hg, 95% CI +1.2, +6.6; P < 0.01) blood pressure; it had no significant effect on regional vascular resistances (+4.7 mm Hg ml-1 s, 95% CI -5.6, +15.0). Effects of ibuprofen on renal prostanoid synthesis were less marked, and there was no change in indices of renal function or hydro-electrolytic balance.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
86.
BACKGROUND: Insulin resistance (IR) and inflammation are associated with increased risk of cardiovascular disease in the general population. Continuous glucose absorption in peritoneal dialysis (PD) may induce hyperglycemia and hyperinsulinemia. METHODS: We evaluated IR in nondiabetic patients receiving PD, and analyzed the association between IR and systemic inflammation biomarkers by performing a cross-sectional study on ambulatory dialysis. A total of 25 nondiabetic patients receiving PD and 25 healthy individuals, matched for gender, age, and body mass index (BMI), were included. The PD group was composed of 11 men and 14 women, with a mean age of 47 +/- 14 years and mean BMI of 25.5 +/- 4.7 kg/m(2). The control group was composed of 10 men and 15 women, with a mean age of 45 +/- 12 years and BMI of 24.0 +/- 2.8 kg/m(2). RESULTS: IR was evaluated by the homeostasis model assessment method (HOMA-IR). Inflammation was assessed through high-sensitivity C-reactive protein (CRP) and fibrinogen. Body composition and truncal fat were evaluated by dual energy x-ray absorptiometry. HOMA-IR was significantly higher (P < .0001) in subjects receiving PD (4.9, range: 2.3-9.3 mmol/L x muU/mL) compared with healthy subjects (1.2, range: 0.4-4.8 mmol/L x muU/mL). As expected, compared with controls, patients receiving PD had significantly higher levels of insulin (26.5 +/- 7.5 muU/mL vs 6.3 +/- 3.4 muU/mL; P < .0001), CRP (6.3, range: 0.3-61.1 mg/L vs 2.4, range: 0.6-5.9 mg/L; P = .001), and fibrinogen (379 +/- 101 mg/dL vs 268 +/- 66 mg/dL; P < .0001). However, there were no significant differences in body and truncal fat mass between the groups. A significant correlation between HOMA-IR and fibrinogen (Rho = 0.48; P = .01) was observed. However, no correlation was found between HOMA-IR and CRP. Also, no significant correlations were found between HOMA-IR and body fat mass (Rho = 0.11), and between HOMA-IR and truncal fat mass (Rho = 0.19). CONCLUSIONS: Patients receiving PD demonstrate a state of IR that is associated with high circulating levels of fibrinogen. This suggests that hyperfibrinogenemia may be involved in the pathogenesis of IR in this setting.  相似文献   
87.

Backround  

Diverticulosis is a common disease in the western society with an incidence of 33–66%. 10–25% of these patients will develop diverticulitis. In order to prevent a high-risk acute operation it is advised to perform elective sigmoid resection after two episodes of diverticulitis in the elderly patient or after one episode in the younger (< 50 years) patient. Open sigmoid resection is still the gold standard, but laparoscopic colon resections seem to have certain advantages over open procedures. On the other hand, a double blind investigation has never been performed. The Sigma-trial is designed to evaluate the presumed advantages of laparoscopic over open sigmoid resections in patients with symptomatic diverticulitis.  相似文献   
88.
Follicular lymphoma (FL) is the second most common subtype of non-Hodgkin’s lymphoma (NHL) in the Western world. FL constitutes the most frequent indolent lymphoma, well characterized by its clinical presentation related to nodal involvement and its morphologic and biologic features. It is often managed as an incurable disease. However, several active therapeutic approaches from the ‘wait and watch” strategy to the allogeneic transplantation are available for management of patients with FL and clearly have changed the natural history of this disease, achieving a long-term disease-free survival. Therapeutic decision is mostly conditioned by patient’s characteristics, stage, histological grade, tumor burden, and risk-predicting factors. This article try to summarizes the diagnosis and treatment of this heterogeneous group of patients.  相似文献   
89.
T cells are known to develop a critical role in the pathogenesis of atopic dermatitis (AD) and bronchial asthma. T cells involved in AD express the skin homing receptor CLA, but no lung homing receptor has been identified in bronchial asthma. We compared different cell markers and the cytokine production in T cells from children with AD or bronchial asthma. We studied the involvement of CLA+ and CLA- T-cell subpopulations in these diseases. We studied 20 children with acute AD lesions, 15 with mild persistent asthma, and 15 non-atopic controls. All patients were sensitized to house dust mite (DP) and evaluated during the acute phase. Total and specific IgE were measured by immunoassay and the expression of different cell markers and the cytokine production was analyzed by flow cytometry in peripheral blood mononuclear cells. Total IgE was significantly higher in AD children and IgE to DP in the asthmatic children. There was a significant increase in CD25+ CD4+ cells in asthmatic children and in HLA-DR+ CD4+ and HLA-DR+ CD8+ cells in AD. In the CD4+ subsets, there was an increase in IL-13, IL-5 and TNF-alpha in AD compared to controls, a decrease in IFN-gamma in asthmatic children compared to controls, and an increase in IL-13, IL5, IL2, TNF-alpha, and IFN-gamma in the AD compared to asthmatic children. Changes in cytokine production were mainly detected in CLA+ cells in AD and in CLA- cells in asthma. Differences exist in total and specific IgE, activation markers, and cytokine patterns between AD children and children with asthma, with the former expressing a Th2 pattern whereas in asthmatic children we only detected a decrease in IFN-gamma. Moreover, the subpopulations (CLA+ vs. CLA-) expressing these changes were different, indicating that the underlying mechanisms in the two diseases are not exactly the same.  相似文献   
90.
This review focuses on estrogen role on human male physiology. Biological estrogen actions on male reproductive system are summarized with particular regard to the effects of congenital estrogen deprivation in men. The effects of estrogen on spermatogenesis, hormonal secretion and gonadotropin feedback and on sexual behavior are discussed. It is remarked that the role of estrogens in male reproduction is a very recent acquisition in reproductive endocrinology, but it promises new future fields of research to be investigated as well as the possible disclosure of new strategies in clinical practice.  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