全文获取类型
收费全文 | 2340篇 |
免费 | 157篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 6篇 |
妇产科学 | 8篇 |
基础医学 | 176篇 |
口腔科学 | 759篇 |
临床医学 | 203篇 |
内科学 | 599篇 |
皮肤病学 | 12篇 |
神经病学 | 94篇 |
特种医学 | 144篇 |
外国民族医学 | 1篇 |
外科学 | 144篇 |
综合类 | 158篇 |
预防医学 | 53篇 |
眼科学 | 1篇 |
药学 | 80篇 |
中国医学 | 24篇 |
肿瘤学 | 48篇 |
出版年
2024年 | 3篇 |
2023年 | 55篇 |
2022年 | 62篇 |
2021年 | 112篇 |
2020年 | 93篇 |
2019年 | 212篇 |
2018年 | 232篇 |
2017年 | 97篇 |
2016年 | 81篇 |
2015年 | 68篇 |
2014年 | 216篇 |
2013年 | 144篇 |
2012年 | 94篇 |
2011年 | 137篇 |
2010年 | 73篇 |
2009年 | 101篇 |
2008年 | 104篇 |
2007年 | 157篇 |
2006年 | 79篇 |
2005年 | 86篇 |
2004年 | 78篇 |
2003年 | 43篇 |
2002年 | 18篇 |
2001年 | 31篇 |
2000年 | 25篇 |
1999年 | 21篇 |
1998年 | 21篇 |
1997年 | 17篇 |
1996年 | 10篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 2篇 |
排序方式: 共有2516条查询结果,搜索用时 15 毫秒
1.
2.
Stress Testing Versus CT Angiography in Patients With Diabetes and Suspected Coronary Artery Disease
Abhinav Sharma Adrian Coles Nishant K. Sekaran Neha J. Pagidipati Michael T. Lu Daniel B. Mark Kerry L. Lee Hussein R. Al-Khalidi Udo Hoffmann Pamela S. Douglas 《Journal of the American College of Cardiology》2019,73(8):893-902
Background
The optimal noninvasive test (NIT) for patients with diabetes and stable symptoms of coronary artery disease (CAD) is unknown.Objectives
The purpose of this study was to assess whether a diagnostic strategy based on coronary computed tomographic angiography (CTA) is superior to functional stress testing in reducing adverse cardiovascular (CV) outcomes (CV death or myocardial infarction [MI]) among symptomatic patients with diabetes.Methods
PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) was a randomized trial evaluating an initial strategy of CTA versus functional testing in stable outpatients with symptoms suggestive of CAD. The study compared CV outcomes in patients with diabetes (n = 1,908 [21%]) and without diabetes (n = 7,058 [79%]) based on their randomization to CTA or functional testing.Results
Patients with diabetes (vs. without) were similar in age (median 61 years vs. 60 years) and sex (female 54% vs. 52%) but had a greater burden of CV comorbidities. Patients with diabetes who underwent CTA had a lower risk of CV death/MI compared with functional stress testing (CTA: 1.1% [10 of 936] vs. stress testing: 2.6% [25 of 972]; adjusted hazard ratio: 0.38; 95% confidence interval: 0.18 to 0.79; p = 0.01). There was no significant difference in nondiabetic patients (CTA: 1.4% [50 of 3,564] vs. stress testing: 1.3% [45 of 3,494]; adjusted hazard ratio: 1.03; 95% confidence interval: 0.69 to 1.54; p = 0.887; interaction term for diabetes p value = 0.02).Conclusions
In diabetic patients presenting with stable chest pain, a CTA strategy resulted in fewer adverse CV outcomes than a functional testing strategy. CTA may be considered as the initial diagnostic strategy in this subgroup. (PROspective Multicenter Imaging Study for Evaluation of Chest Pain [PROMISE]; NCT01174550) 相似文献3.
Ewelina Kazimierczyk Andrzej Eljaszewicz Paula Zembko Ewa Tarasiuk Malgorzata Rusak Agnieszka Kulczynska-Przybik Marta Lukaszewicz-Zajac Karol Kaminski Barbara Mroczko Maciej Szmitkowski Milena Dabrowska Bozena Sobkowicz Marcin Moniuszko Agnieszka Tycinska 《Pharmacological reports : PR》2019,71(1):73-81
Background
Acute myocardial infarction (AMI) causes irreversible myocardial damage and release of inflammatory mediators, including cytokines, chemokines and miRNAs. We aimed to investigate changes in the levels of cytokines (IL-6, TNF-α and IL-10), miRNAs profiles (miR-146 and miR-155) and distribution of different monocyte subsets (CD14++CD16-, CD14++CD16+, CD14+CD16++) in the acute and post-healing phases of AMI.Methods
In eighteen consecutive AMI patients (mean age 56.78?±?12.4 years, mean left ventricle ejection fraction – LVEF: 41.9?±?9.8%), treated invasively, monocyte subsets frequencies were evaluated (flow cytometry), cytokine concentrations were analyzed (ELISA) as well as plasma miRNAs were isolated twice – on admission and after 19.2?±?5.9 weeks of follow-up. Measurements were also performed among healthy volunteers.Results
AMI patients presented significantly decreased frequencies of classical cells in comparison to healthy controls (median 71.22% [IQR: 64.4–79.04] vs. 84.35% [IQR: 81.2–86.7], p?=?0.001) and higher percent of both intermediate and non-classical cells, yet without statistical significance (median 6.54% [IQR: 5.14–16.64] vs. 5.87% [IQR: 4.48–8.6], p?=?0.37 and median 5.99% [IQR: 3.39–11.5] vs. 5.26% [IQR: 3.62–6.2], p?=?0.42, respectively). In AMI patients both, analyzed plasma miRNA concentrations were higher than in healthy subjects (miR-146: median 5.48 [IQR: 2.4–11.27] vs. 1.84 [IQR: 0.87–2.53], p?=?0.003; miR-155: median 25.35 [IQR: 8.17–43.15] vs. 8.4 [IQR: 0.08–16.9], p?=?0.027, respectively), and returned back to the values found in the control group in follow-up. miR-155/miR-146 ratio correlated with the frequencies of classical monocytes (r=0.6, p?=?0.01) and miR-155 correlated positively with the concentration of inflammatory cytokines ? IL-6 and TNF-α.Conclusions
These results may suggest cooperation of both pro-inflammatory and anti-inflammatory signals in AMI in order to promote appropriate healing of the infarcted myocardium. 相似文献4.
随着生物医用材料研制和医学的迅速发展,以及生活水平、医疗保健、康复水平的提高,人们对自身组织、器官及骨骼缺损的修复和置换方面的要求日益提高,尤其对人造骨骼和人工关节的需求越来越广泛。由于计算机断层成像技术CT(computed tomography)已经成为显示和研究人体内部结构非常有用的手段,将计算机辅助设计技术CAD(Computer aided design)和计算机辅助工程CAE(Computer aided Engineering)等相关技术应用于人造骨骼和内置假体的设计,不仅可以提高产品的设计质量,同时,结合CT和计算机三维重建方法, 相似文献
5.
Dr. med. Dr. med. dent. Christof Holberg Katja Schwenzer Ingrid Rudzki-Janson 《Journal of orofacial orthopedics》2005,66(2):110-121
Abstract
Background and Aim:
The prediction of soft tissue esthetics is important for achieving an optimal esthetic outcome in orthodontic treatment planning. Applicable procedures have so far been restricted to two-dimensional profile predictions that have not proven to be very reliable. The goal of this investigation was therefore to develop a novel finite element-based procedure that allows a three-dimensional, easily visualized, quantitative analysis and prediction of soft tissue behavior for the clinician. The procedure to be developed should be easy to handle and not entail any additional radiation exposure for the patient.
Material and Methods:
Using a three-dimensional scanner, the facial surfaces of 20 probands were digitalized and individual FEM models were generated.
Results:
After reduction of data redundancy via several conversion steps, a patient-specific simulation model was prepared consisting of 20,000 to 40,000 individual elements to which specific physical properties could be assigned. The average time required for generating a virtual model was 50 minutes. Problems occurring during model generation were rare (mainly shadowing phenomena and movement artifacts).
Conclusion:
The procedure outlined herein makes the reliable generation of patient-specific simulation models possible for facial soft tissue prediction in orthodontics. 相似文献
6.
目的构建pCool—GST—ICAD/CAD的表达载体,并存大肠杆菌BL21(DE3)中表达具有生物学活性的CAD核酸酶?方法用PCR扩增CAD基因,将扩增产物克隆入pCool—GST—ICAD载体中构建出pCool—GST—ICAD/CAD表达载体。经酶切和电泳鉴定正确后,在大肠杆菌BL21(DE3)中诱导表达,表达产物经亲和层析、离子交换层析及凝胶过滤等方法分离纯化。最后用SDS—PAGE和DNA降解实验进行鉴定。结果构建了pCool—GST—ICAD/CAD原核表达载体,重组载体转化后表达出毫克级水平的GST—ICAD/CAD蛋白复合体。经分离纯化后得到纯度很好的CAD—ICAD篮白复合体,在SDS—PAGE电泳上旱现清晰的两条蛋白带。经DNA降解实验证明纯化所得的CAD蛋白具有非特异性降解DNA的核酸酶作用。结论成功制备了具有生物学活性的CAD核酸酶,为进一步研究细胞凋亡的作用机制提供了有效的制剂。 相似文献
7.
8.
9.
Steven D. Forman Jonathan D. Cohen Mark Fitzgerald William F. Eddy Mark A. Mintun Douglas C. Noll 《Magnetic resonance in medicine》1995,33(5):636-647
The typical functional magnetic resonance (fMRI) study presents a formidable problem of multiple statistical comparisons (i.e, > 10,000 in a 128 x 128 image). To protect against false positives, investigators have typically relied on decreasing the per pixel false positive probability. This approach incurs an inevitable loss of power to detect statistically significant activity. An alternative approach, which relies on the assumption that areas of true neural activity will tend to stimulate signal changes over contiguous pixels, is presented. If one knows the probability distribution of such cluster sizes as a function of per pixel false positive probability, one can use cluster-size thresholds independently to reject false positives. Both Monte Carlo simulations and fMRI studies of human subjects have been used to verify that this approach can improve statistical power by as much as fivefold over techniques that rely solely on adjusting per pixel false positive probabilities. 相似文献
10.
Silvia Obenauer Christian Sohns Carola Werner Eckhardt Grabbe 《Journal of digital imaging》2006,19(3):258-263
The goal of this study was to evaluate the performance of a computer-aided detection (CAD) system in full-field digital mammography
(Senographe 2000D, General Electric, Buc, France) in finding out carcinomas depending on the parenchymal density. A total
of 226 mediolateral oblique (MLO) and 186 craniocaudal (CC) mammographic views of histologically proven cancers were retrospectively
evaluated with a digital CAD system (ImageChecker V2.3 R2 Technology, Los Altos, CA, USA). Malignant tumors were detected
correctly by CAD in MLO view in 84.85% in breasts with parenchymal tissue density of the American College of Radiology (ACR)
type 1, in 70.33% of the ACR type 2, in 68.12% of the ACR type 3, and in 69.70% of the ACR type 4. For the CC view, similar
results were found according to the ACR types. Using the chi-square and McNemar tests, there was no statistical significance.
However, a trend of better detection could be seen with decreasing ACR type. In conclusion, there seems to be a tendency for
breast tissue density to affect the detection rate of breast cancer when using the CAD system. 相似文献