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   608篇
  免费   32篇
  国内免费   1篇
耳鼻咽喉   9篇
儿科学   25篇
妇产科学   25篇
基础医学   85篇
口腔科学   12篇
临床医学   62篇
内科学   107篇
皮肤病学   1篇
神经病学   57篇
特种医学   21篇
外科学   75篇
预防医学   42篇
眼科学   30篇
药学   54篇
肿瘤学   36篇
  2024年   2篇
  2023年   3篇
  2022年   3篇
  2021年   11篇
  2020年   17篇
  2019年   11篇
  2018年   14篇
  2017年   15篇
  2016年   15篇
  2015年   11篇
  2014年   17篇
  2013年   31篇
  2012年   45篇
  2011年   32篇
  2010年   26篇
  2009年   26篇
  2008年   32篇
  2007年   39篇
  2006年   40篇
  2005年   40篇
  2004年   46篇
  2003年   32篇
  2002年   28篇
  2001年   10篇
  2000年   10篇
  1999年   10篇
  1998年   5篇
  1997年   5篇
  1996年   2篇
  1995年   3篇
  1994年   4篇
  1993年   3篇
  1992年   5篇
  1991年   6篇
  1990年   3篇
  1989年   3篇
  1988年   4篇
  1987年   4篇
  1986年   3篇
  1985年   3篇
  1984年   3篇
  1983年   3篇
  1982年   3篇
  1981年   1篇
  1980年   2篇
  1979年   2篇
  1977年   1篇
  1976年   3篇
  1975年   2篇
  1973年   2篇
排序方式: 共有641条查询结果,搜索用时 15 毫秒
61.
BACKGROUND: Knowledge of the prevalence of peripheral arterial disease (PAD) in patients with chronic renal failure (CRF) is limited because of a lack of uniformity in disease definition and recognition. Furthermore, little is known of the prevalence of medial arterial calcification (MAC) in patients with CRF. Our goal is to study the prevalence of PAD and MAC defined by ankle brachial index (ABI) or toe brachial index (TBI) measurements in a Finnish population of patients with CRF consisting of predialysis and dialysis patients, as well as renal transplant recipients. METHODS: We examined 136 patients with CRF and 59 control subjects. Fifty-nine of the patients with CRF had moderate to severe predialysis CRF, 36 patients were on dialysis treatment, and 41 were renal transplant recipients. Mean age of patients was 51.9 +/- 11.5 years, and 39 patients (29%) had diabetes. ABI and TBI were measured by means of photoplethysmography. The definition of PAD required an ABI value of 0.90 or less, a TBI value of 0.60 or less, or a previous positive lower-extremity angiogram result. ABI values of 1.3 or greater or incompressible arteries at ankle level indicated MAC. The presence of claudication was determined by an interview. RESULTS: Prevalences of PAD on this study were 22.0% in patients with predialysis CRF, 30.6% in patients on dialysis treatment, 14.6% in renal transplant recipients, and 1.7% in the control group (P = 0.001). Prevalences of MAC were 23.7%, 41.7%, 23.1%, and 3.4% (P < 0.001), respectively. Only 9 patients had claudication, and 6 of those patients had PAD. CONCLUSION: Both asymptomatic PAD and MAC are common in patients with CRF. Therefore, we recommend the use of both ABI and TBI measurements in the evaluation of PAD in patients with CRF.  相似文献   
62.
Aim: To investigate the association between gastroduodenal mucosal damage and symptoms of the digestive tract in children with juvenile chronic arthritis (JCA) Methods: This was a prospective, open, non-randomized study. Gastroscopy was performed on 45 children with active JCA in 1996-2000. Gastrointestinal symptoms before and during the treatment were noted, as was the length of antirheumatic medication, for which the data were retrospectively assessed. Plasma haemoglobin (Hb) and mean corpuscular volume (MCV) levels and erythrocyte sedimentation rate (ESR) were analysed. Mucosal biopsies were obtained for histology and Helicobacter pylori culture. All patients were taking non-steroidal anti-inflammatory drugs (NSAIDs) and 11 (24.4%) were on peroral steroids; 16 (35.6%) were receiving hydorxychloroquine, 9 salazopyrine, 5 myocrisine and 14 methotrexate. Results: Seven children (15.6%) were found to have active inflammation in their gastric and/or duodenal mucosa, two having ulcers and two being infected with H. pylori. Abnormal endoscopic findings were more common in symptomatic children (n = 24) than in children without symptoms (n = 21) (75% vs 38%, p = 0.017). There was no clear association between the Hb or MCV level and the degree of gastroduodenal inflammation (p = 0.98 and 0.7, respectively). Significantly more children (66.6% vs 33.3%) experienced abdominal pain after beginning medical therapy than before therapy (p = 0.02).

Conclusion: Endoscopic evaluation of patients with JCA and receiving NSAIDs should be considered at least in symptomatic cases.  相似文献   
63.
In this population-based study, all 314 episodes of β-haemolytic streptococcal bacteraemia in adult patients in the Pirkanmaa area, Finland, during the 10-year period 1995–2004 were retrospectively reviewed. Altogether, 92 cases of bacteraemia caused by Lancefield group A β-haemolytic streptococci (GAS), 76 caused by group B β-haemolytic streptococci (GBS), 18 caused by group C β-haemolytic streptococci (GCS) and 128 caused by group G β-haemolytic streptococci (GGS) were identified. The most important finding was that the incidence of GGS increased during the study period. Disruption of the cutaneous barrier was a very common predisposing factor in GAS and GGS bacteraemias. Skin infections were the presenting clinical manifestations in two-thirds of GAS and GGS bacteraemias.  相似文献   
64.
65.
Background: The significance of ST‐segment depression in acute coronary syndrome has been the subject of debate for many decades. Studies indicate that different manifestations of ST/T changes may have significantly different prognostic implications. Methods and Results: We studied the correlation of ST/T changes in 12‐lead electrocardiography recorded during pain, to clinical and angiographic findings and in‐hospital prognosis, in patients with non‐ST‐elevation acute coronary syndrome and elevated troponin levels. Fifty consecutive patients could be differentiated into two groups: (1) 25 patients with ST‐segment depression and a negative T wave maximally in leads V4–5, (2) 25 patients with ST‐segment depression and a positive T wave in the precordial lead with maximal ST‐segment depression. Patients in group I had significantly more often left main or left main equivalent coronary artery disease; 76% versus 8% (P < 0.001), heart failure; 40% versus 4% (P = 0.005), and higher in‐hospital mortality; 24% versus 0% (P = 0.02), than patients in group II. The troponin levels did not differ significantly between the groups. Conclusions: In patients with non‐ST‐elevation acute coronary syndrome and elevated troponin levels two subgroups could be identified. Transient ST‐segment depression and a negative T wave maximally in leads V4–5 during anginal pain predicts left main, left main equivalent, or severe three‐vessel coronary artery disease with high sensitivity and specificity. In patients with ST‐segment depression and a positive T wave, there is a high probability of one‐vessel disease.  相似文献   
66.
We previously observed degranulated mast cells (MC) in association with perivascular brain edema formation during focal cerebral ischemia. Brain MC are typically located perivascularly and contain potent fast-acting vasoactive and proteolytic substances. We examined in a rat model of transient middle cerebral artery occlusion (MCAO) whether, in the early phase of ischemia, MC regulate microcirculation, the blood-brain barrier (BBB) permeability, and edema formation. First, animals received MC inhibitor (cromoglycate), MC-degranulating drug (compound 48/80), or saline. Thereafter, we performed transient MCAO in gene-manipulated MC-deficient rats and their wild-type (WT) littermates, calculating brain swelling, visualizing BBB leakage by intravenously administered Evans blue albumin, and determining neutrophil infiltration with light microscopy. Cerebral blood flow, monitored by laser-Doppler flowmetry in separate experiments, was similar among pharmacological treatments. Ischemic swelling resulted in increased hemispheric volume of 13.4%+/-1.0% in controls, 8.1%+/-0.4% (39% reduction) after cromoglycate, and 25.2%+/-2.0% (89% increase) after compound 48/80 (P<0.05). Early ischemic BBB leakage was reduced by 51% after cromoglycate, and 50% enhanced by compound 48/80 (P<0.05). The cromoglycate group showed 37% less postischemic neutrophil infiltration than did controls (P<0.05). Furthermore, MC-deficient rats responded to focal ischemia with 58% less brain swelling (6.7%+/-1.2%) than did their WT littermates (15.8%+/-1.4%, P<0.05). Blood-brain barrier damage was 47% lower in MC-deficient rats than in the WT (P<0.05). Neutrophil infiltration after MCAO was decreased 47% in MC-deficient rats in comparison to WT (P<0.05). Pharmacological MC inhibition thus appears to deserve further investigation regarding reduction of brain swelling and inflammation early after stroke.  相似文献   
67.
We have examined the expression of 2 type IV collagen degrading enzymes (Mr 72,000 and 92,000 type IV collagenases) in human skin cancer by in situ hybridization. In all cases of infiltrating carcinomas of squamous cell (9 of 9) and basal cell (5 of 5) types, messenger RNA for the Mr 72,000 type IV collagenase was present in numerous fibroblasts. These were especially abundant in the stroma adjacent to the invasive tumor nodules. Malignant cells were negative for mRNA for the Mr 72,000 enzyme in all cases as were all other epithelial as well as endothelial cells. mRNA for the Mr 92,000 type IV collagenase was present in all 9 squamous cell and in 3 of the 5 basal cell carcinomas. In all these cases, a subpopulation of tissue macrophages was found to be positive, while malignant cells showed a signal for Mr 92,000 type IV collagenase in 6 of the squamous cell carcinomas but in none of the basal cell carcinomas. In all cases, the signal for this mRNA was confined to cells located at the tumoral/stromal interface or in the close vicinity of tumor nodules. No mRNA for any of the 2 collagenases was detected in 3 biopsies of normal skin. In vitro studies have indicated that collagenases are involved in the degradation of the extracellular matrix during cancer invasion. The present findings are consistent with such a role of the Mr 72,000 and 92,000 type IV collagenases in squamous and basal cell carcinomas in situ. The findings also demonstrate that degradative enzymes are not necessarily produced by the malignant cells themselves but may be generated by induction or recruitment of nonmalignant stromal cells.  相似文献   
68.
In Africa today one of the main strategies to reduce malaria infection during pregnancy is the promotion of intermittent preventive treatment (IPT). To date only a few studies have investigated the factors affecting compliance to IPT. This medical anthropology study aims to describe these factors from the perspective of pregnant women in rural Malawi. We examine women's knowledge and perceptions about the use of medication in pregnancy and the timing and motivation concerning use of antenatal clinic (ANC) services. In addition, the circumstances and interaction at the ANC and the IPT implementation process are described. The data were collected by applying an ethnographic approach, including focus group discussions (n=8), in-depth interviews (n=34), drug identification exercises, participant observation and a 'knowledge, attitudes and practices' survey (n=248). This study discovered several factors affecting IPT. These were: unclear messages about IPT with sulfadoxine-pyrimethamine (SP) from nurses; timing of SP-1; periodic shortages of SP; women's limited understanding of IPT-SP; tendency for late enrolment; and nurses' underperformance. The results of this study show that understanding of the multiple contexts affecting malaria prevention is important, and that ethnographic research is useful for discovering and solving problems beyond the scope of many other research approaches.  相似文献   
69.
70.
Accurate and rapid electrocardiographic interpretation is of crucial importance in acute coronary syndrome (ACS). Computerized electrocardiographic algorithms are often used in out-of-hospital settings. Their accuracy should be carefully validated in ACS, particularly in ST-elevation myocardial infarction. This study evaluated the comparative accuracy of lead-specific computer-based versus manual measurements of the J-point, ST-segment, and T-wave deviations in standard 12-lead electrocardiograms (ECGs) (excluding lead aVR). Sixty-nine consecutive patients with suspected ACS were included. The interobserver reliability in the determination of ST-segment deviation>or=0.2 mV in leads V2 and V3 was very good (kappa=0.94 and 0.93, respectively). Agreement between a cardiologist and the computer regarding ST elevation>or=0.2 mV in lead V2 was moderate (kappa=0.72) and in V3 was very good (kappa=0.85). For ST depression or elevation>or=0.05 mV in lead LIII, agreement was good and moderate (kappa=0.79 and 0.51, respectively). Bland-Altman analysis demonstrated clinically acceptable limits of agreement comparing measurements of the J point and the T wave, but clinically inadequate limits of agreement with respect to ST-segment deviation, between the electrocardiographer and the computer. The optimal cut-off points were 0.115 mV (sensitivity 89%, specificity 98%) for the computer program to detect ST elevation>or=0.2 mV and 0.045 mV (sensitivity 74%, specificity 99%) for revealing ST elevation>or=0.1 mV. It was found that automatically measured ST-segment deviations were smaller than those manually measured. In conclusion, a correction should be performed to obtain optimal results in the automated analysis of ECGs, because the results have important implications for clinical decision making.  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