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   1527篇
  免费   69篇
  国内免费   5篇
耳鼻咽喉   16篇
儿科学   72篇
妇产科学   39篇
基础医学   166篇
口腔科学   48篇
临床医学   78篇
内科学   296篇
皮肤病学   18篇
神经病学   113篇
特种医学   47篇
外科学   300篇
综合类   50篇
预防医学   52篇
眼科学   24篇
药学   144篇
中国医学   10篇
肿瘤学   128篇
  2024年   6篇
  2023年   17篇
  2022年   12篇
  2021年   50篇
  2020年   26篇
  2019年   43篇
  2018年   45篇
  2017年   29篇
  2016年   32篇
  2015年   41篇
  2014年   57篇
  2013年   73篇
  2012年   93篇
  2011年   118篇
  2010年   54篇
  2009年   43篇
  2008年   77篇
  2007年   93篇
  2006年   67篇
  2005年   68篇
  2004年   54篇
  2003年   38篇
  2002年   64篇
  2001年   40篇
  2000年   30篇
  1999年   24篇
  1998年   15篇
  1997年   10篇
  1996年   6篇
  1995年   12篇
  1992年   16篇
  1991年   14篇
  1990年   12篇
  1989年   17篇
  1988年   15篇
  1987年   23篇
  1986年   17篇
  1985年   16篇
  1984年   7篇
  1983年   8篇
  1981年   7篇
  1980年   7篇
  1979年   14篇
  1978年   10篇
  1977年   7篇
  1976年   8篇
  1974年   8篇
  1973年   9篇
  1970年   5篇
  1968年   12篇
排序方式: 共有1601条查询结果,搜索用时 15 毫秒
21.
Journal of Thrombosis and Thrombolysis - We present a novel case of a patient with nephrotic syndrome and previous left pneumonectomy who had a massive pulmonary embolism of his remnant right...  相似文献   
22.
OBJECTIVE: Energy metabolism is altered in the diabetic heart. However, direct in vivo evidence that diabetes impairs energetics at the chamber level is lacking. Therefore, we investigated the effect of diabetes on left ventricular (LV) energetics in a chronic ovine model. METHODS: Diabetes was induced in Merino-cross sheep with streptozotocin. Experiments were performed in five animals following 12 months untreated diabetes and six animals served as controls. Open-chest anesthetized sheep were instrumented to determine the LV pressure-volume relationship, oxygen consumption and free fatty acid uptake. RESULTS: Diabetes impaired LV contractility (1.5+/-0.5 vs. 2.3+/-0.5 mmHg/ml, P<0.01). Stroke work was preserved but stroke work efficiency (stroke work/pressure-volume area) deteriorated (52+/-4 vs. 58+/-3%, P<0.01). Plasma free fatty acid levels increased (1885+/-1078 vs. 354+/-203 mmol/l, P<0.01) as did LV free fatty acid uptake (312+/-278 vs. 90+/-47 micromol/beat per 100 g LV, P=0.04). Contractile efficiency decreased (31.9+/-1.4 vs. 50.0+/-8.7%, P<0.01) while unloaded oxygen consumption did not change significantly. Therefore, LV oxygen utilization efficiency (stroke work/LV oxygen consumption) was compromised in the diabetic heart (14.9+/-2.8 vs. 24.3+/-4.0%, P<0.001). CONCLUSION: This is the first study to demonstrate that diabetes alters ventricular energetics in vivo. LV oxygen utilization efficiency is impaired as a consequence of decreased contractile efficiency and stroke work efficiency. Impaired efficiency of oxygen utilization may explain in part the increased sensitivity of the diabetic heart to ischemia and the accelerated deterioration of ventricular function in diabetic patients.  相似文献   
23.
Proceedings of the National Academy of Sciences, India Section B: Biological Sciences - Present study was undertaken to optimize the extraction conditions for the recovery of anthocyanins from an...  相似文献   
24.
Primary myelofibrosis is a chronic myeloproliferative neoplasm characterized by cytopenias, leukoerythroblastosis, extramedullary hematopoiesis, hepatosplenomegaly and bone marrow fibrosis. Primary myelofibrosis is a rare disorder in adults; children are even less commonly affected by this entity, with the largest pediatric case series reporting on three patients. Most literature suggests spontaneous resolution of myelofibrosis without long term complications in the majority of affected children. We describe the clinical, pathologic, and molecular characteristics and outcomes of nineteen children with primary myelofibrosis treated in our center from 1984 to 2011. Most patients had cytopenia significant enough to require supportive therapy. No child developed malignant transformation and only five of the 19 children (26%) had spontaneous resolution of disease. Sequence analyses for JAK2V617F and MPLW515L mutations were performed on bone marrow samples from 17 and six patients, respectively, and the results were negative. In conclusion, analysis of this large series of pediatric patients with primary myelofibrosis demonstrates distinct clinical, hematologic, bone marrow, and molecular features from adult patients.  相似文献   
25.
AIM: To evaluate aspects of cognition impacted by individuals with and without normal tension glaucoma. METHODS: Fifty normal tension glaucoma (NTG) and 50 control patients ≥50y of age were recruited from the UCSF Department of Ophthalmology. Demographic data and glaucoma parameters were extracted from electronic medical records for both groups. Tests of executive function [Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (EXAMINER)] and learning and memory [California Verbal Learning Test–Second Edition (CVLT-II)] were administered to both NTG and controls. Race, handedness, best-corrected visual acuity, maximum intraocular pressure, optic nerve cup-to-disc ratio, visual field and optic nerve optical coherence tomography parameters, and a measure of general health (Charlson Comorbidity Index) were compared between NTG and controls as well as within NTG subgroups. Multivariate linear regression was used to compare group performances on the EXAMINER battery and CVLT-II while controlling for age, sex, and years of education. RESULTS: NTG and controls were comparable with respect to age, sex, race, education, handedness, and the Charlson Comorbidity Index (P>0.05 for all). Performance on the EXAMINER composite score and the CVLT-II did not differ between NTG and controls (P>0.05 for both). CONCLUSION: This is the first prospective study in which the cognitive function of subject with NTG were evaluated using a comprehensive, computerized neurocognitive battery. Subjects with NTG do not perform worse than unaffected controls on tests of executive function, learning, and memory. Results do not support the hypothesis that individuals with NTG are at higher risk for cognitive dysfunction and/or dementia.  相似文献   
26.
27.
This study aims to develop a spatial model of bone for quantitative assessments of bone mineral density and microarchitecture. A spatially structured network model for bone microarchitecture was systematically investigated. Bone mineral-forming foci were distributed radially according to the cumulative normal distribution, and Voronoi tessellation was used to obtain edges representing bone mineral lattice. Methods to simulate X-ray images were developed. The network model recapitulated key features of real bone and contained spongy interior regions resembling trabecular bone that transitioned seamlessly to densely mineralized, compact cortical bone-like microarchitecture. Model-simulated imaging profiles were similar to patients’ X-ray images. The morphometric metrics were concordant with microcomputed tomography results for real bone. Simulations comparing normal and diseased bone of 20–30 to 70–80 year-olds demonstrated the method’s effectiveness for modeling osteoporosis. The novel spatial model may be useful for pharmacodynamic simulations of bone drugs and for modeling imaging data in clinical trials.  相似文献   
28.
29.

Introduction

Platelets are involved in regeneration at sites of pathology, apart from their role in clotting. A preparation composed mainly of platelets (platelet-rich plasma gel) applied to sites of bony pathology, after surgical treatment of lesions, may hasten bone regeneration.

Materials and methods

An autologous platelet-rich plasma (PRP) gel was prepared using a standardized technique, without using thrombin clot accelerator, and applied to surgical site in six patients of study group. Five patients were enrolled as controls, in whom PRP gel was not used. The differences in the occurrence of radiographic changes between the study and control group at 6, 12, 18 and 24 weeks after surgery were analysed with chi-square test. Intragroup radiographic changes, i.e. within the study and control groups occurring over the 24 weeks of follow-up, were analysed with Friedman test.

Results

A trend towards more rapid healing was observed in the study group at 6, 12, 18 and 24 weeks. However, these differences between the study and control group were not statistically significant. Both the study and control group demonstrated significant healing changes over the 24 weeks of follow-up.

Conclusions

It is possible to prepare platelet-rich plasma gel without using thrombin clot accelerator. PRP, as prepared and applied to surgical sites in this study, was not observed to significantly enhance bone regeneration. All surgical sites, both in the PRP and control group, showed significant healing changes over 6 months.  相似文献   
30.
Abdominal Radiology - To discuss the imaging appearances of various pathologies affecting adult male urethra and to review the role of imaging in the assessment of artificial urinary sphincters and...  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