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   3480篇
  免费   132篇
  国内免费   18篇
耳鼻咽喉   23篇
儿科学   61篇
妇产科学   41篇
基础医学   546篇
口腔科学   61篇
临床医学   197篇
内科学   888篇
皮肤病学   52篇
神经病学   211篇
特种医学   63篇
外科学   692篇
综合类   7篇
预防医学   100篇
眼科学   37篇
药学   199篇
中国医学   17篇
肿瘤学   435篇
  2023年   16篇
  2022年   35篇
  2021年   61篇
  2020年   34篇
  2019年   57篇
  2018年   86篇
  2017年   51篇
  2016年   51篇
  2015年   63篇
  2014年   98篇
  2013年   98篇
  2012年   182篇
  2011年   186篇
  2010年   120篇
  2009年   110篇
  2008年   171篇
  2007年   182篇
  2006年   223篇
  2005年   218篇
  2004年   206篇
  2003年   217篇
  2002年   205篇
  2001年   115篇
  2000年   99篇
  1999年   105篇
  1998年   67篇
  1997年   27篇
  1996年   31篇
  1995年   29篇
  1994年   22篇
  1993年   27篇
  1992年   51篇
  1991年   52篇
  1990年   44篇
  1989年   50篇
  1988年   32篇
  1987年   41篇
  1986年   28篇
  1985年   20篇
  1984年   14篇
  1983年   16篇
  1982年   9篇
  1980年   8篇
  1979年   9篇
  1978年   9篇
  1977年   6篇
  1974年   7篇
  1970年   5篇
  1969年   8篇
  1966年   4篇
排序方式: 共有3630条查询结果,搜索用时 13 毫秒
81.
Using serial intravascular ultrasound (IVUS), integrated-backscatter IVUS, and optical coherence tomography, we observed rapidly progressive cardiac allograft vasculopathy (CAV) and donor-transmitted plaque in the left anterior descending artery. Late-phase everolimus-resistant CAV had a rapidly progressive course (maximal intimal thickness [MIT] increased by 0.5 mm between years 3 and 4 after cardiac transplantation, from MIT growth <0.5 mm at year 1). Conversely, the donor-transmitted plaque grew slowly (0.1 mm increase during the same period). Tissue characteristics in the 2 segments were also different; CAV had eccentric, noncalcified, and lipid-rich components and was associated with macrophage accumulation, whereas donor-transmitted atherosclerosis presented with typical features of atherosclerosis (ie, fibrocalcific plaque). CAV with late-phase progression involves everolimus resistance and features of vulnerable plaques seen in nontransplantation patients and is independent of donor-transmitted atherosclerosis.  相似文献   
82.
83.
The fibrin-related markers (FRMs), including soluble fibrin (SF), d-dimer and fibrin and fibrinogen degradation products (FDP) are considered to be useful for the diagnosis of thrombosis; however, evidence for the diagnosis of thrombosis by SF is still not well established. The present study was designed to evaluate the usefulness of SF in the diagnosis of venous thromboembolism (VTE). The plasma concentrations of FRMs were measured in 551 in-patients suspected to have a VTE. The plasma levels of SF, d-dimer and FDP were significantly higher in patients with VTE than patients without VTE and those were significantly higher in patients without VTE than in healthy volunteers. In a receiver operating characteristic analysis for the diagnosis of VTE, the area under the curve was 0.950 for SF, 0.933 for FDP and 0.805 for d-dimer. The appropriate cut-off values for the diagnosis were as follows SF 5.9 μg/ml, FDP 2.1 μg/ml and d-dimer 4.8 μg/ml. To obtain a 100% negative predictive value for the diagnosis of VTE, the SF was less than 5.2 μg/ml, FDP was less than 1.3 μg/ml, and d-dimer was less than 0.5 μg/ml. Our findings suggest that the SF assay is useful for the diagnosis and exclusion of VTE.  相似文献   
84.
85.
A pregnancy that is complicated by a uterine prolapse is rare and primarily occurs in multiparous women during their first or second trimester. In the present report, we describe a case of a 31-year-old nulliparous woman who experienced sudden uterine prolapse at 38 weeks’ gestation without labor pains. The cervix was congested, the cervical mucosa was partially lacerated, and bleeding was noted; the protruding cervix could not be repositioned into her vagina. Although the cervical congestion worsened over time, she still did not experience any labor pains. She was delivered by emergency cesarean section. Following delivery, the prolapse promptly improved and did not recur before her 1-month postpartum examination. To our knowledge, this is the first case where uterine prolapse occurred in a nulliparous woman during late gestation.  相似文献   
86.
Heart transplantation started in Japan in 1999. Since then, 50 transplants have been performed at our center. We performed histopathological analyses of the 50 explanted hearts and the post‐transplant biopsy specimens. The median age of recipients was 39 years. The primary diseases before transplant were idiopathic dilated cardiomyopathy in 33 patients (66%), hypertrophic cardiomyopathy in seven (14%), restrictive cardiomyopathy in one, arrhythmogenic right ventricular cardiomyopathy in one, and secondary cardiomyopathy in eight (16%). Before transplantation, 47 patients (94%) had left ventricular assist devices. No severe cardiovascular failure due to allograft rejection occurred. The post‐transplant survival rate was 97.6% at 1 year and 93.1% at 10 years. One recipient was lost to sepsis from myelodysplastic syndrome in the fourth year, one died of multiple organ failure and peritonitis 8 months after transplant. Another patient died of recurrent post‐transplant lymphoproliferative disorders (PTLD). Mild cardiac dysfunction occurred in seven recipients in the early postoperative period. Moderate acute cellular rejection occurred in six patients (12%), and antibody‐mediated rejection occurred in three (6%). The number of heart transplants performed in Japan is very small. However, the outstanding 10‐year survival rate is due to donor evaluation and post‐transplant care resulting in low grade rejection. Pathological evaluation has also greatly contributed to the results.  相似文献   
87.
Ventricular assist devices (VADs) have long been used as bridge to transplant therapy (BTT). Nipro-Toyobo paracorporeal pulsatile-flow VAD (nt-VAD) was the only device available until April 2011, when implantable continuous-flow VADs (cf-VADs) became available. Although cf-VADs are central to BTT, nt-VAD remains a necessary option. We aimed to clarify the role of nt-VAD in an era of increasing cf-VAD use. We retrospectively reviewed patients who underwent VAD implantation at the National Cerebral and Cardiovascular Center from May 2011 to March 2013. Characteristics were compared between the nt-VAD and cf-VAD groups. Twenty-nine patients (mean age 37.7 ± 11.1 years, 23 males) underwent VAD implantation. Fifteen patients initially received nt-VADs, although 4 were converted to cf-VADs. Of these 15 patients, 3 were too small for cf-VADs and 2 needed bilateral ventricular support. The remaining 10 patients received nt-VADs (7 patients at INTERMACS level 1 and 3 at level 2). The nt-VAD group patients had significantly more preoperative mechanical circulatory support and were in a more critical condition before VAD implantation than the cf-VAD group. The 2-year survival rate was not significantly different. Despite the critical conditions of nt-VAD patients, their overall survival is not statistically inferior to that of cf-VAD patients. nt-VAD is a good option as a BTC for the patient with urgent and critical condition.  相似文献   
88.
Purpose:The estimation of functional connectivity (FC) measures using resting state functional MRI (fMRI) is often affected by head motion during functional imaging scans. Head motion is more common in the elderly than in young participants and could therefore affect the evaluation of age-related changes in brain networks. Thus, this study aimed to investigate the influence of head motion in FC estimation when evaluating age-related changes in brain networks.Methods:This study involved 132 healthy volunteers divided into 3 groups: elderly participants with high motion (OldHM, mean age (±SD) = 69.6 (±5.31), N = 44), elderly participants with low motion (OldLM, mean age (±SD) = 68.7 (±4.59), N = 43), and young adult participants with low motion (YugLM, mean age (±SD) = 27.6 (±5.26), N = 45). Head motion was quantified using the mean of the framewise displacement of resting state fMRI data. After preprocessing all resting state fMRI datasets, several resting state networks (RSNs) were extracted using independent component analysis (ICA). In addition, several network metrics were also calculated using network analysis. These FC measures were then compared among the 3 groups.Results:In ICA, the number of voxels with significant differences in RSNs was higher in YugLM vs. OldLM comparison than in YugLM vs. OldHM. In network analysis, all network metrics showed significant (P < 0.05) differences in comparisons involving low vs. high motion groups (OldHM vs. OldLM and OldHM vs. YugLM). However, there was no significant (P > 0.05) difference in the comparison involving the low motion groups (OldLM vs. YugLM).Conclusion:Our findings showed that head motion during functional imaging could significantly affect the evaluation of age-related brain network changes using resting state fMRI data.  相似文献   
89.
90.
AIM To study the safety of insertion of metallic stents in elderly patients with unresectable distal malignant biliary obstruction.METHODS Of 272 patients with unresectable distal malignant biliary obstruction, 184 patients under the age of 80 were classified into Group A, and 88 subjects aged 80 years or more were classified into Group B. The safety of metallic stent insertion, metal stent patency period, and the obstruction rate were examined in each group.RESULTS In Group B, patients had a significantly worse per-formance status, high blood pressure, heart disease, cerebrovascular disease, and dementia; besides the rate of patients orally administered antiplatelet drugs or anticoagulants tended to be higher(P 0.05). Metallic stents were successfully inserted in all patients. The median patency period was 265.000 ± 26.779(1-965) d; 252.000 ± 35.998(1-618) d in Group A and 269.000 ± 47.885(1-965) d in Group B, with no significant difference between the two groups. Metallic stent obstruction occurred in 82 of the 272(30.15%) patients; in 53/184(28.80%) patients in Group A and in 29/88(32.95%) of those in Group B, showing no significant difference between the two groups. Procedural accidents due to metal stent insertion occurred in 24/272(8.8%) patients; in 17/184(9.2%) of patients in Group A and in 7/88(8.0%) of those in Group B, with no significant difference between the two groups, either.CONCLUSION These results suggested that metallic stents can be safely inserted to treat unresectable distal malignant biliary obstruction even in elderly patients aged 80 years or more.  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