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   3027篇
  免费   161篇
  国内免费   17篇
耳鼻咽喉   28篇
儿科学   42篇
妇产科学   31篇
基础医学   294篇
口腔科学   159篇
临床医学   311篇
内科学   760篇
皮肤病学   47篇
神经病学   223篇
特种医学   102篇
外科学   367篇
综合类   8篇
一般理论   1篇
预防医学   123篇
眼科学   23篇
药学   348篇
中国医学   8篇
肿瘤学   330篇
  2023年   22篇
  2022年   51篇
  2021年   84篇
  2020年   65篇
  2019年   59篇
  2018年   88篇
  2017年   66篇
  2016年   80篇
  2015年   74篇
  2014年   131篇
  2013年   160篇
  2012年   253篇
  2011年   226篇
  2010年   133篇
  2009年   109篇
  2008年   186篇
  2007年   185篇
  2006年   191篇
  2005年   173篇
  2004年   160篇
  2003年   139篇
  2002年   130篇
  2001年   28篇
  2000年   25篇
  1999年   26篇
  1998年   30篇
  1997年   21篇
  1996年   19篇
  1995年   24篇
  1994年   13篇
  1993年   16篇
  1992年   15篇
  1991年   10篇
  1990年   13篇
  1989年   14篇
  1988年   6篇
  1987年   12篇
  1986年   9篇
  1985年   12篇
  1984年   13篇
  1983年   16篇
  1982年   12篇
  1981年   13篇
  1980年   11篇
  1979年   5篇
  1976年   6篇
  1973年   5篇
  1972年   6篇
  1971年   4篇
  1968年   4篇
排序方式: 共有3205条查询结果,搜索用时 15 毫秒
21.
Traditional risk factors such as hypertension, diabetes, dyslipidemia, obesity and metabolic syndrome, as well as additional nontraditional risk factors, can damage the kidney directly and by promoting intrarenal atherogenesis. Evidence indicates that increased oxidative stress and inflammation may mediate most of the effects of risk factors on the kidney. Clinical studies have demonstrated a relationship between oxidative stress and inflammatory biomarkers, and a few studies indicate an inverse correlation of oxidative stress biomarkers with estimated glomerular filtration rate (eGFR). Further, surrogate indexes of atherosclerosis such as intima-media thickness and aortic pulse wave velocity have been demonstrated to be related to plasma concentrations of markers of endothelial activation, inflammation and fibrosis in patients with different stages of chronic kidney disease (CKD). Moreover, plasma concentrations of high-sensitivity C-reactive protein have been shown to be increased and related to left ventricular mass in CKD individuals having left ventricular hypertrophy. In contrast, in these patients, decreases in fetuin-A plasma levels have been reported. Considering the complex background of the pathophysiological changes characterizing CKD patients, we can consider cardiovascular disease a multifactorial complication of CKD.  相似文献   
22.
23.
OBJECTIVE: To present an institutional experience with the use of right liver grafts in adult patients and to assess the practicability and efficacy of this procedure by analyzing the results. SUMMARY BACKGROUND DATA: Living donor liver transplantation (LDLT) for the pediatric population has gained worldwide acceptance. In the past few years, LDLT has also become feasible for adult patients due to technical evolution in hepatobiliary surgery and increased experience with reduced-size and split-liver transplants. Nevertheless, some graft losses remain unexplained and are possibly due to unrecognized venous outflow problems. METHODS: From April 1998 to September 2002, we performed 74 right LDLTs (segments 5-8). The 74 donors were selected from 474 candidates according to standard protocol. The median age of the donors was 35 years (range 18-58 years) and 51 years (range 18-64 years) in recipients. Standard and extended indications for transplantation were considered. Over the period reported, technical modifications in the bile duct anastomosis (duct-to-duct, end-to-end, or end-to-side) and a new graft implantation technique that provides maximized venous outflow, leading to outcome improvement, were developed. RESULTS: 64.9% of patients had liver cirrhosis and 35.1% had malignancy. While 44 donors (59.5%) presented an uneventful postoperative course, 27% minor (pleural effusion, pneumonia, venous thrombosis, wound infection, incisional hernia) and 13.5% major (biliary leakage, death of a donor due to unrecognized hereditary liver disease, and consecutive liver insufficiency) complications were documented. In recipients, 23% biliary complications and 6.8% hepatic artery thrombosis occurred. The overall patient and graft survival rate after 1 year was 79.4% and 75.3%, respectively. In cases with extended indication, the patient survival rate was 74% and the graft survival rate 68% at 12 months. Using technical modifications in the last 10 recipients, including 2 critically decompensated cirrhotics, the survival rate was 100% at a median follow-up of 3.5 months. CONCLUSIONS: In our transplant program, living donor liver transplantation has become a standard option in the adult patient population. The critical issue of this procedure is donor morbidity. Technical improvements in the harvesting and implantation of right grafts can also offer hope to patients with challenging forms of end-stage liver disease or malignant liver tumors.  相似文献   
24.
The fear that patients with high-mathematical model for end stage liver disease (MELD) score may not be suitable candidates for segmental grafts because of their need for greater liver mass has continued to push the transplant community toward the use of whole LT (WLT) in preference to split LT (SLT). In order to define the outcome of segmental liver transplantation in a better manner in high-MELD patients (score ≥26), we queried the UNOS registry for graft and patient survival results according to MELD score in adult patients receiving WLT and SLT in the United States from the inception of MELD allocation (February 27, 2002) through March 9, 2007. A total of 316 adult patients received a SLT as compared with 20 778 WLTs. Patient and graft survival rates at 6 and 12 months were comparable for all MELD ranges, including the 'high-MELD' recipients (e.g. at MELD score 31–35, patients' and grafts' survival rates at 12 months was 87.5% in SLT group vs. 84.4% and 76.7% in WLT group respectively). The results even at higher MELD scores (i.e. >35) were more than acceptable. In conclusion, patient and graft survival rates for SLT in high-MELD adult patients are comparable to the same for WLT.  相似文献   
25.
Summary β-1-galactosyl-0-hydroxylysine (GH) was measured in the urine of 59 women and 48 men, aged 30–79 years, by High Performance Liquid Chromatography (HPLC) of the dansylated derivative. Vertebral mineral density, measured by quantitative computed tomography (QCT), and urinary GH were inversely correlated (r=−0.74;P<0.001). High rate of bone mineral loss is associated with a high urinary GH excretion. Measurement of GH in urine provides a simple and noninvasive method for the evaluation of the extent of bone resorption in large groups of subjects and appears to be more specific than urinary hydroxyproline excretion.  相似文献   
26.
Background: At present, there are no meaningful and sophisticated computer games that simultaneously allow the treatment of movement disorders such as Parkinson's syndrome. In particular, there are no systems to consider the severity of the disease and the physical skills of the patient.

Methods: A computer game using the Microsoft Kinect as markerless sensor for the 3?D recognition of the patient’s movement was developed to support the rehabilitation. The scenario of a basketball game was created after determining that the movement like throwing a ball and the correct posture of the body are important. A study based on system usability was performed with 15 patients to evaluate the system.

Results: The technical feasibility of a computer-assisted training system for supporting patients with Parkinson‘s disease has been demonstrated. No markers on the patient are required for movement detection and allow a user-friendly handling. Regarding the usability study, the patients were accepting of such a system and its at-home use and symptoms like ‘freezing’ and the Pisa syndrome can be treated.

Conclusions: The physiotherapist can be assisted by the developed rehabilitation system. An objective measurement of the patient’s training progress delivers valuable information to adjust the training sessions for every patient individually. Due to its modular character, the system can also be applied to other diseases or sports injuries and offers the basis for further development.  相似文献   

27.
We investigated the effects of viral infection on Tissue Factor (TF) expression and activity in mice within the myocardium to understand increased thrombosis during myocarditis. Mice were infected with coxsackie virus B3 (CVB3) and the hearts were collected at day 4, 8 and 28 post infection (p.i.). Myocardial TF expression and cellular activity as well as plasma activity were analyzed from CVB3 infected mice by Western blot, chromogenic Factor Xa generation assay, in situ staining for active TF and immunohistochemistry. In addition to TF expression, hemodynamic parameters were measured during the time course of infection. Furthermore, we analyzed myocardial tissues from patients with suspected inflammatory cardiomyopathy. TF protein expression was maximally 5-fold elevated 8 days p.i. in mice and remained increased on day 28 p.i. (P < 0.001 vs. non-infected controls). Alterations in TF expression were associated with fibrin deposits within the myocardium. The TF pathway inhibitor protein expression in the myocardium was not altered during myocarditis. Active cellular TF co-localized with CD3 positive cells and VCAM-1 positive endothelial cells in the myocardium. The TF expression was positively correlated with the amount of infiltrating CD3 and Mac3 positive cells (Spearman-Rho ρ = 0.749 P < 0.0001 for CD3+ and ρ = 0.775 P < 0.0001 for Mac3+; N = 35). Increased myocardial TF expression was associated with a 2-fold elevated plasma activity (P < 0.05 vs. non-infected controls). In the human hearts, the TF expression correlated postively with an endothelial cell activation marker (ρ = 0.523 P < 0.0001 for CD62E; N = 54). Viral myocarditis is a hypercoagulative state which is associated with increased myocardial TF expression and activity. Upregulation of TF contributes to a systemic activation of the coagulation cascade.  相似文献   
28.
29.
30.

Background

Numerous methods have been proposed that use submaximal loads to predict one repetition maximum (1RM). One common method applies standard linear regression equations to load and average vertical lifting velocity (Vmean) data developed during squat jumps or three bench press throw (BP-T). The main aim of this project was to determine which combination of three submaximal loads during BP-T result in the most accurate prediction of 1RM Smith Machine bench press strength in healthy individuals.

Methods

In this study combinations of three BP-T loads were used to predict 1RM Smith Machine bench press strength. Additionally, we examined whether regression models developed using peak vertical bar velocity (Vpeak), rather than Vmean, provide the most accurate prediction of Smith Machine bench press 1RM. 1RM Smith Machine bench press strength was measured directly in 12 healthy regular weight trainers (body mass?=?80.8?±?5.7 kg). Two to three days later a linear position transducer attached to the collars on a Smith Machine was used to record Vmean and Vpeak during BP-T between 30 and 70% of 1RM (10% increments).

Results

Repeated measures analysis of variance testing showed that the mean values for slope and ordinate intercept for the regression models at each of the load ranges differed significantly depending on whether Vmean or Vpeak were used in the prediction models (P?<?0.001). Conversely, the abscissa intercept did not differ significantly between either measure of vertical bar velocity at each load range. The key finding in this study was that 1RM Smith Machine bench press strength can be determined with high relative accuracy by examining Vmean and Vpeak during BP-T over three loads, with the most precise models using Vpeak during loads representing 30, 40 and 50% of 1RM (R 2 ?=?0.96, SSE?=?4.2 kg).

Conclusions

These preliminary findings indicate that exercise programmers working with normal healthy populations can accurately predict Smith Machine 1RM bench press strength using relatively light load Smith Machine BP-T testing, avoiding the need to expose their clients to potentially injurious loads.
  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