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   2507篇
  免费   136篇
  国内免费   7篇
耳鼻咽喉   37篇
儿科学   160篇
妇产科学   226篇
基础医学   215篇
口腔科学   36篇
临床医学   208篇
内科学   622篇
皮肤病学   35篇
神经病学   144篇
特种医学   73篇
外科学   358篇
综合类   39篇
一般理论   1篇
预防医学   180篇
眼科学   37篇
药学   151篇
中国医学   6篇
肿瘤学   122篇
  2023年   18篇
  2022年   32篇
  2021年   48篇
  2020年   27篇
  2019年   42篇
  2018年   63篇
  2017年   45篇
  2016年   56篇
  2015年   63篇
  2014年   75篇
  2013年   127篇
  2012年   163篇
  2011年   165篇
  2010年   85篇
  2009年   94篇
  2008年   185篇
  2007年   204篇
  2006年   178篇
  2005年   197篇
  2004年   185篇
  2003年   164篇
  2002年   134篇
  2001年   59篇
  2000年   39篇
  1999年   42篇
  1998年   8篇
  1997年   8篇
  1996年   7篇
  1995年   7篇
  1994年   7篇
  1993年   3篇
  1992年   12篇
  1991年   8篇
  1990年   9篇
  1989年   13篇
  1988年   17篇
  1987年   13篇
  1986年   5篇
  1985年   7篇
  1984年   4篇
  1983年   3篇
  1982年   3篇
  1981年   2篇
  1979年   4篇
  1978年   4篇
  1977年   3篇
  1975年   4篇
  1968年   2篇
  1966年   3篇
  1963年   1篇
排序方式: 共有2650条查询结果,搜索用时 15 毫秒
31.
ObjectiveThe aim was to compare coronary high-definition CT (HDCT) with standard-definition CT (SDCT) angiography as to radiation dose, image quality and accuracy.ResultsThe intraclass correlation coefficient (ICC) of measured vessel attenuation values in SDCT between the two radiologists was exceedingly good. The ICC was higher in HDCT. The radiation dose of HDCT was higher than that of SDCT. The mean tube current was 180 (mA) in HDCT and 147(mA) in SDCT with the same tube voltage (kVp). There was no significant difference between image quality.ConclusionHDCT has a higher radiation dose but has much more atenuation and the spatial resolution which improve measurement accuracy for imaging coronary arteries.  相似文献   
32.
Rationale: Among the extracellular modulators of Bmp (bone morphogenetic protein) signaling, Bmper (Bmp endothelial cell precursor-derived regulator) both enhances and inhibits Bmp signaling. Recently we found that Bmper modulates Bmp4 activity via a concentration-dependent, endocytic trap-and-sink mechanism. Objective: To investigate the molecular mechanisms required for endocytosis of the Bmper/Bmp4 and signaling complex and determine the mechanism of Bmper's differential effects on Bmp4 signaling. Methods and Results: Using an array of biochemical and cell biology techniques, we report that LRP1 (LDL receptor-related protein 1), a member of the LDL receptor family, acts as an endocytic receptor for Bmper and a coreceptor of Bmp4 to mediate the endocytosis of the Bmper/Bmp4 signaling complex. Furthermore, we demonstrate that LRP1-dependent Bmper/Bmp4 endocytosis is essential for Bmp4 signaling, as evidenced by the phenotype of lrp1-deficient zebrafish, which have abnormal cardiovascular development and decreased Smad1/5/8 activity in key vasculogenic structures. Conclusions: Together, these data reveal a novel role for LRP1 in the regulation of Bmp4 signaling by regulating receptor complex endocytosis. In addition, these data introduce LRP1 as a critical regulator of vascular development. These observations demonstrate Bmper's ability to fine-tune Bmp4 signaling at the single-cell level, unlike the spatial regulatory mechanisms applied by other Bmp modulators.  相似文献   
33.
Iron overload increases the risk of infections, veno-occlusive disease and hepatic dysfunction in post-transplant period. Our objective was to investigate the association of pre-transplant ferritin levels with complications and survival after allogeneic hematopoietic stem cell transplantation (alloHSCT).We retrospectively analysed 84 patients' data who had undergone allogeneic HSCT into two groups: patients with a serum ferritin level ≥ 1000 ng/ml, and patients with <1000 ng/ml at the time of HSCT.Cox-regression analysis showed that pre-transplant serum ferritin levels were significantly higher in patients who had at least one infectious event compared with those who had no any infectious event in the post-transplant 100 days (p<0.023). Overall survival (OS) and disease-free survival (DFS) rates were significantly higher in patients with a time-to-tx interval 12 months (p=0.002 and p=0.008 respectively). A higher risk of death was observed in high-ferritin group (hazard ratio=2.27, CI:1.01-5.09, p=0.023 for OS and hazard ratio=2.49, CI:1.12-5.53 p=0.039 for DFS). No significant effect on OS and DFS among groups was observed for variables conditioning regimen, gender and diagnosis. Acute GVHD was more common in patients with a ferritin level ≥ 1000 ng /mL, but this was not statistically significant (p>0.05). There was no statistical significance in both groups (ferritin ≥ 1000 ng /mL and ferritin <1000 ng/mL) for relapse rates (p>0.05). Platelet and neutrophil engaftment day was not found statistically significant compared with both groups (p=0.273 and p=0.882, respectively). Pre-transplant ferritin levels may predict poor outcomes in patients who had undergone allogeneic hematopoietic stem cell transplantation.  相似文献   
34.
The objective was to investigate the predictive factors for avascular necrosis (AVN) of bone in patients with systemic lupus erythematosus (SLE). The records of 868 patients with SLE from four centers were reviewed retrospectively. Forty-nine patients with AVN were identified. A total of 154 patients with SLE who did not have clinically apparent AVN during the follow-up were evaluated as a control group. The demographic, clinical, laboratory and management characteristics of these two groups of patients were recorded according to predefined protocol and compared. The prevalence of AVN was detected 6% in our SLE population. The highest dose corticosteroid administered within 4?months and total cumulative prednisolone dose were significantly higher in the SLE patients with AVN. The use of cytotoxic agent significantly higher proportion of patients with AVN. AVN tends to develop more frequently in male gender and younger patients. Oral ulcer, pleuritis, Raynaud??s phenomenon, cutaneous vasculitis, lymphadenopathy, autoimmune thyroiditis, peripheral neuropathy and Sj?gren??s syndrome were higher incidence in SLE patients with AVN. The bilateral femoral heads were the commonest site of involvement of AVN in our patients with SLE.  相似文献   
35.
36.
37.
The purposes of this study were to detect the prevalence of ownership of a home sphygmomanometer among hypertensive subjects through a nation-wide survey, to investigate parameters affecting ownership of a sphygmomanometer, to compare how home blood pressure monitoring (HBPM) was actually used in daily practice with some aspects of the current guidelines, and to discuss what we implemented to increase the reliability of HBPM in a developing country. A total of 2747 hypertensive patients from 34 cities, representative of the Turkish population, were enrolled in the study. A multiple-choice questionnaire was administered to each participant using the computer-assisted telephone interviewing method. Among 2747 hypertensive patients, 1281 of them (46.6%) had a home sphygmomanometer. Most of the patients were using wrist devices. The factors associated with ownership of a sphygmomanometer were female gender, older age, obesity, higher educational status, higher income level, living in urban areas, awareness of hypertension and anti-hypertensive drug usage. Only 16% of the devices were used on the advice of a physician. The patients learned usage of their device mainly from the sellers and their relatives. The ownership of a home sphygmomanometer is common among hypertensive patients in Turkey, but regular monitoring of blood pressure before physician visits is rare despite common ownership of these devices. Daily practice of HBPM in Turkey was far from the recommendations of the current guidelines. More effort is needed to improve the reliability of HBPM.  相似文献   
38.

Purpose

Atherosclerosis is responsible for the high mortality rate in end-stage renal disease patients. Defining risk factors for atherosclerosis may lead to reduction in cardiovascular disease through modification of these factors. Peritoneal dialysis (PD) patients are subjected to high glucose loads on a daily basis, which results in considerable weight gain and an increase in waist circumference (WC). WC as an indicator of abdominal obesity is a risk factor for atherosclerosis in the general population. Carotid artery intima media thickness (CIMT) measurement is a reliable method for the detection of early atherosclerosis. The aim of this study was to investigate the relationship between WC and CIMT and to define risk factors associated with CIMT in PD patients.

Methods

Fifty-five PD patients and 40 healthy controls were included. Atherosclerosis was assessed using measurement of CIMT. Fasting blood was collected for analysis. Anthropometric parameters (age, weight, BMI, and WC) were measured.

Results

Peritoneal dialysis patients had higher WC (93.9 ± 1.7 vs. 87.3 ± 1.2 cm, p < 0.05) and CIMT (0.70 ± 0.02 vs. 0.57 ± 0.01 mm, p < 0.01) than the control group. On univariate analysis, age, WC, plaque formation, and D/P creatinine were positively correlated with CIMT, whereas residual renal function, albumin, ultrafiltration volume, and D/D0 glucose were negatively correlated. On multivariate analysis, only age, WC, and plaque formation showed correlation (p < 0.001).

Conclusions

Carotid artery intima media thickness is associated with age, plaque formation, and WC in PD patients. WC measurement is a simple, inexpensive, reproducible, and reliable method of evaluating atherosclerosis risk in PD patients and should be assessed at every visit. Appropriate counsel should be provided to patients with greater WC who are deemed to be at risk for atherosclerosis.  相似文献   
39.
ObjectiveThe aim of the present study is to determine the frequency of enthesopathy in fibromyalgia (FM) by using a newly developed ultrasonography (US) method, the Madrid Sonography Enthesitis Index (MASEI).MethodsThis study was conducted on 38 consecutive patients with FM and 48 healthy sex- and age-matched controls. Six entheseal sites (olecranon tuberosity, superior and inferior poles of patella, tibial tuberosity, superior and inferior poles of calcaneus) on both lower limbs were evaluated. All US findings were identified according to MASEI. Scores of patients and controls were compared by Student's t-test and Mann-Whitney U-test. Validity was analysed by receiver operating characteristic curve. Values of P < 0.05 were considered significant.ResultsTotal enthesitis score was 7.39 ± 4.99 (mean ± SD) among FM patients and 3.7 ± 3.22 among healthy controls (P < 0.001). The receiver operating characteristic curve established an ultrasound score of > 3.5 in the FM group as the best cut-off point to differentiate between cases and controls. No statistically significant correlation was found between the MASEI score and the FM disease duration, and the location of the tender points.ConclusionsMisdiagnoses of FM are harmful to patients and the community, and the presence of enthesopathy among FM patients increases. Its detection with the MASEI score may help to discriminate FM patients presenting with ill-defined symptoms and signs, in order to prevent mistreatment.  相似文献   
40.
Kaposi's sarcoma (KS) is an unusual tumor principally affecting the skin of the lower extremities. Although the association between KS and renal transplant has been well documented, there are a few KS cases in the literature associated with membranoproliferative glomerulonephritis or other glomerular diseases. This report presents a patient with membranoproliferative glomerulonephritis (MPGN) who developed KS following treatment with long-term medium dose glucocorticoid and short-term additional immunosuppressives. The KS cases associated with glomerulonephritis are also reviewed. KS is a rare complication in glomerular diseases that may (or may not) be related to immunosuppression. Hence, immunosuppression treatment should be carefully planned in glomerulonephritis treatment and avoided if they are not essentially necessary.  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