全文获取类型
收费全文 | 289篇 |
免费 | 8篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 11篇 |
妇产科学 | 3篇 |
基础医学 | 21篇 |
口腔科学 | 5篇 |
临床医学 | 21篇 |
内科学 | 33篇 |
皮肤病学 | 2篇 |
神经病学 | 28篇 |
特种医学 | 106篇 |
外科学 | 36篇 |
综合类 | 5篇 |
预防医学 | 5篇 |
眼科学 | 2篇 |
药学 | 7篇 |
肿瘤学 | 13篇 |
出版年
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2016年 | 2篇 |
2015年 | 8篇 |
2014年 | 7篇 |
2013年 | 12篇 |
2012年 | 8篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 4篇 |
2007年 | 8篇 |
2006年 | 14篇 |
2005年 | 5篇 |
2004年 | 13篇 |
2003年 | 15篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 12篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有299条查询结果,搜索用时 15 毫秒
91.
Effect on platelet properties of exposure to temperatures below 20 degrees C for short periods during storage at 20 to 24 degrees C 总被引:1,自引:0,他引:1
Background : When platelet concentrates (PCs) are shipped over long distances, it is not always possible to ensure that their temperature is maintained at 20 to 24°C. In addition, PCs are not agitated as during routine storage. Study Design and Methods : Studies have been conducted to evaluate how exposure to temperatures below 20°C in the absence of agitation influences properties of platelets. In initial studies, exposure to 4°C for 3 or 5 hours or to 12°C for 5 or 17 hours on Day 2 of a 5- to 6-day storage period was associated with a loss of discoid shape. This was reflected by slightly lower but statistically different morphology scores after storage compared to those observed with control platelets that were stored only at 20 to 24°C. In addition, a qualitative difference in morphology was noted in controls and PCs held at 16°C for 17 hours. In more detailed studies, both the in vivo viability and in vitro properties of platelets exposed between Day 1 and Day 2 to either 12°C or 16°C for 17 hours were evaluated. The protocol involved a paired study design (n = 4 for each exposure temperature) with the simultaneous storage of two identical PCs, one exposed to 12 or 16°C and the other one maintained at 20 to 24°C throughout the 5-day storage. Results : Exposure to 12°C significantly reduced (p < 0.05 by paired t test) the in vivo recovery to 37.6 ± 13.8 percent (mean ± 1 SD) from 47.8 ± 11.5 percent and the survival time to 2.0 ± 0.3 days from 6.5 ± 1.4 days. On exposure to 16°C, the differences in viability from those of control units were much less but still significant. The in vivo recovery was 42.7 ± 3.8 percent compared to 49.2 ± 3.0 percent and the survival time was 3.5 ± 1.2 days compared to 6.6 ± 0.3 days. The loss of in vivo viability of the test platelets was associated with a loss of discoid shape, as reflected by morphology scores, extent of shape change, and mean platelet volume. In addition, platelet metabolism also appeared to be affected, as suggested by increased lactate production. All of the in vitro properties except for total ATP and residual glucose that were statistically different from those of controls on exposure to 12°C were also significantly different on exposure to 16°C. Conclusion : These findings demonstrate that platelets undergo substantial changes in in vivo viability and in vitro properties when they are exposed to temperatures below 20°C for short periods. 相似文献
92.
Haughton VM; Rimm AA; Sobocinski KA; Papke RA; Daniels DL; Williams AL; Lynch R; Levine R 《Radiology》1986,160(3):751-755
The sensitivity and specificity of magnetic resonance (MR) imaging and computed tomography (CT) were compared in blinded readings of images of a consecutive series of patients with subsequently proved diagnoses. Overall, MR imaging was less sensitive than CT because of its lower sensitivity in detecting benign tumors. With a similar experimental protocol, the effects of technical refinements or contrast media on the sensitivity of MR imaging can be determined. 相似文献
93.
One hundred fifty-four patients with stenosis of the iliac artery underwent percutaneous transluminal angioplasty (PTA). These patients were followed for 1-7 years. The long-term results of the PTAs were analyzed by computer, and life tables were generated for dilatations of the iliac arteries with unimpaired flow and for those with an obstruction in the outflow tract. The accumulative 7-year patency rate was 90%, which agrees with other reports. This study demonstrates that the long-term results of PTA of iliac arterial stenoses are competitive with reconstructive vascular surgery. PTA should be the treatment of choice in patients with iliac arterial stenoses. 相似文献
94.
95.
Ventriglia M Bocchio Chiavetto L Scassellati C Squitti R Binetti G Ghidoni R Rossini PM Gennarelli M 《Aging clinical and experimental research》2005,17(6):445-448
BACKGROUND AND AIMS: Substantial evidence supports the hypothesis that impairment of mitochondrial function and increased oxidative damage are involved in the pathogenesis of several neurodegenerative disorders including Alzheimer's disease (AD). Manganese superoxide dismutase (MnSOD) plays a major role in protecting the mitochondrion from oxidative damage due to superoxide radicals and other excited oxygen species. Recent studies have indicated that MnSOD mRNA levels are significantly increased in the lymphocytes of AD patients, supporting the role of oxidative alterations in the pathogenetic mechanism underlying this neurodegeneration. A potentially functional amino acid polymorphism (Ala-9Val) has been described in the signal sequence of enzymes associated with decreased defense capacity against oxidative stress. The object of this study was to investigate the association between this polymorphism of the MnSOD gene and AD in the Italian population. METHODS: The Ala-9Val polymorphism was genotyped by PCR amplification and SSCP analysis in 227 AD patients and 198 healthy controls. RESULTS: No significant differences in genotype or allele frequencies between cases and controls, even after stratification for APOE carrier status, were observed. CONCLUSIONS: Our data suggest that the Ala-9Val polymorphism in the MnSOD gene is not associated with genetic susceptibility in AD patients. 相似文献
96.
The specificity of magnetic resonance (MR) imaging in the diagnosis of multiple sclerosis (MS) has not been measured systematically. Conventional MR head images with sagittal localizer and axial multiple-echo sequences with long repetition times were obtained in 92 patients with clinically verified MS (Schumacher criteria), 100 healthy volunteers, 60 subjects with hypertension, and eight patients with dementia. Two readers, without the aid of any clinical or demographic information, classified each of the 260 studies as MS or not MS. The readers classified the studies again after being supplied with the subjects' ages and sex. True-negative and true-positive diagnoses of MS were tabulated. The specificity of the MR diagnosis of MS (true-negative results in proportion to all non-MS studies) was 95%-99% with all the control groups included. There is a small risk of misinterpreting incidental periventricular white matter foci as plaques of MS in MR studies. 相似文献
97.
Spondylolysis studied with computed tomography 总被引:10,自引:0,他引:10
98.
99.
100.