全文获取类型
收费全文 | 1060篇 |
免费 | 75篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 55篇 |
儿科学 | 23篇 |
妇产科学 | 29篇 |
基础医学 | 121篇 |
口腔科学 | 26篇 |
临床医学 | 118篇 |
内科学 | 145篇 |
皮肤病学 | 27篇 |
神经病学 | 93篇 |
特种医学 | 28篇 |
外科学 | 227篇 |
综合类 | 11篇 |
预防医学 | 68篇 |
眼科学 | 15篇 |
药学 | 85篇 |
中国医学 | 7篇 |
肿瘤学 | 60篇 |
出版年
2024年 | 2篇 |
2023年 | 7篇 |
2022年 | 25篇 |
2021年 | 47篇 |
2020年 | 27篇 |
2019年 | 40篇 |
2018年 | 48篇 |
2017年 | 32篇 |
2016年 | 38篇 |
2015年 | 36篇 |
2014年 | 46篇 |
2013年 | 66篇 |
2012年 | 98篇 |
2011年 | 91篇 |
2010年 | 63篇 |
2009年 | 46篇 |
2008年 | 63篇 |
2007年 | 51篇 |
2006年 | 55篇 |
2005年 | 38篇 |
2004年 | 44篇 |
2003年 | 28篇 |
2002年 | 24篇 |
2001年 | 17篇 |
2000年 | 14篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有1138条查询结果,搜索用时 296 毫秒
1.
Background
The purpose of this study was to compare the outcomes of trauma patients who were injured in a motor vehicle crash and tested positive for alcohol upon hospital arrival versus those who tested negative.Methods
Study data came from the US National Trauma Data Bank (2007–2010). Any blood alcohol concentration (BAC) found at or above the legal limit (≥0.08?g/dL) was considered “alcohol positive”, and if no alcohol was identified through testing, the patient was considered “alcohol negative”. Patients’ demographics including age >?=?14, race, gender, drug test results, systolic blood pressure, heart rate, injury severity score (ISS), and Glasgow Coma Scale (GCS) were included in the study. Propensity score and exact pair matching were performed between the groups using baseline characteristics.Results
From a total of 88,794 patients, 30.9% tested positive and 69.1% tested negative for alcohol. There were significant differences found between the groups regarding age, gender, race, and GCS (all p?<?0.001) as well as a significantly higher in-hospital mortality rate (3.5% vs. 2.7%, p?<?0.001) and median time to patient expiration (4 vs. 3 days, p?<?0.001) in the alcohol negative group. After running both matching scenarios, there was no evidence of a significant difference seen in the rates of in-hospital mortality or the median time to patient expiration between the alcohol groups in either matched comparison.Conclusion
Patients who tested positive for alcohol following a traumatic motor vehicle crash showed no significant increase in in-hospital mortality or time to expiration when compared to propensity score and exact matched patients who tested negative for alcohol. 相似文献2.
3.
4.
5.
Endoscopic Reconstruction of Cranial Base Defects following Endonasal Skull Base Surgery. 总被引:3,自引:0,他引:3
下载免费PDF全文
![点击此处可从《Skull base》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The expanded endonasal approach provides access to the entire ventral skull base for resection of neoplasms involving the skull base and brain. The creation of large defects of the bone and dura endoscopically presents unique reconstructive challenges. A layered reconstruction of the dura with inlay and onlay fascial grafts covered with fat grafts is an effective technique for repair. An intranasal balloon catheter is used to provide counterpressure in the early phase of healing and a lumbar spinal drain is a useful adjunct in patients at increased risk of a cerebrospinal fluid leak. Vascularized flaps may be necessary in some patients receiving radiation therapy. Continued advances in surgical technology and the introduction of new biomaterials will facilitate the reconstruction of skull base defects following endonasal brain surgery. 相似文献
6.
7.
P. J. Vaitkus Dr K. W. Johnston R. L. Bondar F. Stein P. A. J. Bascom Ly Mo M. Kassam L. C. Chadwick J. Mehi R. S. C. Cobbold 《Medical & biological engineering & computing》1990,28(4):306-311
During space flights, several clinical syndromes may be the result of changes in cerebral circulation. The purpose of the
paper is to describe the development and initial evaluation of a system for recording, processing and displaying transcranial
Doppler ultrasound (TCD) waveforms from the middle cerebral artery (MCA) in microgravity. Volunteers were repeatedly subjected
to 15–20 s intervals of microgravity (‘near zero gravity’) during flights on the KC-135 military aircraft. Continuous TCD
recordings from the MCA were stored on magnetic tape. The paper describes the system that was developed to digitise the Doppler
ultrasound data and markers that corresponded to the various levels of microgravity, obtain the maximum and mean Doppler waveforms,
identify the waveforms and quantify them. The results demonstrate the feasibility of making TCD recordings in a microgravity
environment and illustrate excellent performance of the system and its ease of operation. Quantitative waveform analysis of
the recordings from the first subject studied in the supine position showed statistically significant changes in MCA velocity
waveforms during microgravity. 相似文献
8.
Rizzitelli A Vremec D Villadangos JA Mavaddat N Wright MD Shortman K 《European journal of immunology》2005,35(11):3209-3220
Freshly isolated quiescent splenic dendritic cell (DC) subtypes differ in their capacity to activate naive CD4 T cells in culture. The CD8+ DC showed a reduced capacity to stimulate T cell proliferation compared to either of the CD8- DC subsets, regardless of antigen and DC dose. In contrast to CD8- DC, the quiescent CD8+ DC did not induce IFN-gamma production from CD4 T cells. The difference between the DC subtypes appeared to be at the level of initial surface molecule interactions, but could not be attributed to differences in expression of MHC class II or B7 family molecules, or to the expression of Fas ligand on DC. However, when activated by inclusion of the Toll-like receptor 9 ligand CpG in culture, CD8+ DC became potent stimulators of both CD4 T cell proliferation and IFN-gamma production. In contrast, similar activation of CD8- DC produced a more modest increase in capacity to stimulate CD4 T cell proliferation and no increase in capacity to stimulate IFN-gamma production. The difference between a quiescent and an activated state is therefore more extreme for CD8+ than for CD8- DC. The especially tight regulation of the activity of CD8+ DC may be essential for the maintenance of self tolerance. 相似文献
9.
Unrelated patients with achromatopsia, macular degeneration with onset under age 50 years, cone degeneration or dysfunction, cone-rod degeneration, or macular malfunction were screened for mutations in the three genes known to be associated with achromatopsia: the GNAT2 gene encoding the alpha subunit of cone transducin and the CNGA3 and CNGB3 genes encoding the alpha and beta subunits of the cone cGMP-gated cation channel. We found no examples of patients with GNAT2 mutations. Out of 36 achromats, 12 (33%) had mutations in CNGA3 (13 different mutations including five novel mutations) and 12 (33%) had mutations in CNGB3 (six different mutations including four novel mutations). All achromats with CNG mutations had residual, presumably cone function as determined by computer-averaged 30-Hz electroretinograms (ERGs). There was considerable variability in acuity and color vision, with most patients having acuities of 20/200-20/400 and complete absence of color perception, and others having acuities of 20/25-20/40 and some color vision. Two pseudodominant achromatopsia cases were uncovered, both with CNGA3 mutations, including one family in which some compound heterozygotes with achromatopsia mutations were clinically unaffected. We found two novel CNGB3 changes in three patients with juvenile macular degeneration, a phenotype not previously associated with mutations in the cone channel subunits. These patients had subnormal acuity (20/30-20/60), normal to subnormal color vision, and normal to subnormal full-field cone ERG amplitudes. Our results indicate that some patients with channel protein mutations retain residual foveal cone function. Based on our findings, CNGB3 should be considered as a candidate gene to be evaluated in patients with forms of cone dysfunction, including macular degeneration. 相似文献
10.
Mycobacterium bovis BCG cell wall-specific differentially expressed genes identified by differential display and cDNA subtraction in human macrophages
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)