首页 | 官方网站   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   579篇
  免费   9篇
  国内免费   2篇
医药卫生   590篇
  2024年   3篇
  2021年   11篇
  2020年   11篇
  2019年   18篇
  2018年   17篇
  2017年   12篇
  2016年   6篇
  2015年   15篇
  2014年   20篇
  2013年   18篇
  2012年   32篇
  2011年   46篇
  2010年   26篇
  2009年   22篇
  2008年   48篇
  2007年   43篇
  2006年   35篇
  2005年   34篇
  2004年   23篇
  2003年   22篇
  2002年   22篇
  2001年   8篇
  2000年   5篇
  1999年   3篇
  1998年   5篇
  1997年   3篇
  1996年   5篇
  1995年   5篇
  1994年   2篇
  1992年   5篇
  1991年   4篇
  1990年   6篇
  1989年   2篇
  1988年   4篇
  1987年   6篇
  1986年   10篇
  1985年   6篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1979年   2篇
  1978年   3篇
  1977年   3篇
  1976年   3篇
  1975年   2篇
  1956年   1篇
  1955年   1篇
  1940年   1篇
排序方式: 共有590条查询结果,搜索用时 15 毫秒
31.
To assess the validity of the quantitative 201Tl scintimetry in various diseases of the heart (coronary heart disease with and without myocardial infarction, non-coronary cardiomyopathy, scleroderma heart disease and asymmetric septal hypertrophy with IHSS), the 201Tl myocardial uptake values for five standardized projections (a) were correlated with the grade of LAD stenosis, (b) the pattern of myocardial wall motion and (c) were compared with the 201Tl uptake values derived from normal patients. Significant reduction (c) of 201Tl myocardial uptake could in individual cases be evaluated in acute myocardial infarction (95%), in dys- and akinesia (90%), in hypokinesia (71%), in scleroderma heart disease (50%), in non-coronary cardiomyopathy (50%) as well as in normokinesia (28%) when associated with LAD stenosis. The mean values (b) of 201Tl uptake in normo- and hypokinesia significantly differed between these two groups and from those evaluated in dys- and akinesia. The latter group showed the lowest 201Tl uptake values computed which in some cases were very close to the mean mediastinal 201Tl uptake. The correlation (a) of individual 201Tl values demonstrated that 201Tl distribution in the myocardium is not only equivalent to myocardial "perfusion' but is corresponding with the myocardial function. In non-coronary cardiomyopathy reduced 201Tl values sometimes could not be separated from values in coronary heart disease (and myocardial infarction). A regional increase of myocardial mass as in septal hypertrophy correlated well with an augmented 201Tl uptake when referred to the 201Tl storage in the mediastinum.  相似文献   
32.
33.
PURPOSE: The effect of whole body hyperthermia (WBH) at 41.8-42 degrees C on the cellular immune system is still poorly investigated. The aim of this study was to identify genes that become upregulated in peripheral blood lymphocytes (PBLs) of cancer patients during a combined treatment with WBH and chemotherapy by generating complex arrays of cDNA. METHODS: PBLs were obtained from four patients with different malignancies treated with WBH and varying cytostatic schedules before treatment and immediately thereafter. After constructing subtracted cDNA libraries, clones were screened for cDNA induction by dot-blot and semi-quantitative RT-PCR (sq-RT-PCR). RESULTS: Among 192 clones, 39 cDNAs were significantly upregulated. Sequencing revealed three groups of genes for which upregulation of mRNA was confirmed by sq-RT-PCR. The first group consisted of genes encoding for various heat shock proteins (HSP 60, 90a, 90b, 105). Further sq-RT-PCR demonstrated differential expression of HSP27 and HSP70 as well. The second group (calcyclin-binding-protein, haemoglobin-beta-chain) comprised genes without pre-specified association to hyperthermia. The cDNA encoding macrophage-inflammatory-protein-1-beta was also observed and may be associated with the pre-described activation of lymphocyte sub-populations during WBH. CONCLUSION: Treatment with WBH and chemotherapy elicits significant short-term effects on the expression of a variety of genes responsible for cellular integrity, stimulation and migration of immune effector cells. Further investigation is warranted to more clearly define the role of those genes for the clinical effect of WBH.  相似文献   
34.
Background: Histomorphological grading at the invasive front of oral squamous cell carcinomas (OSCCs) may provide useful prognostic information. In the present study, we investigated the presence and prognostic value of activated phosphorylated extracellular signal‐regulated kinases 1 and 2 (p‐ERK1/2) and cyclo‐oxygenase‐2 (COX‐2) both at the invasive front and in central/superficial parts of OSCCs. Methods: Using immunohistochemistry, we assessed the presence of p‐ERK1/2 and COX‐2 in 53 early stage OSCCs. Clinical data were recorded prospectively. The end point was disease‐free survival. Results: p‐ERK1/2 staining was present in almost all tumours. The staining was mostly nuclear in the cells of the invasive front and either nuclear or nuclear/cytoplasmic in central/superficial tumour parts. COX‐2 was observed in almost all tumours (98%) and the staining was often restricted to focal areas. Most tumours were COX‐2 negative at the invasive front. The lowest P‐value in survival analyses was P = 0.06 for p‐ERK1/2 at the invasive front. COX‐2, the histomorphological grading systems and TNM stage were of no prognostic value. Conclusion: p‐ERK1/2 was present in almost all tumours and p‐ERK1/2 may be a prognostic marker at the invasive front of OSCCs. In early stage OSCCs, most tumours did not express COX‐2 at the invasive front.  相似文献   
35.
36.
37.
38.
39.
Awareness of the clinical significance of thoracic aortic aneurismal disease has increased in recent years. As diagnostic tools have improved our ability to identify aortic pathology, surgical outcomes have also improved, making intervention a life-saving option in the majority of cases. Here, we aim to examine the indications for surgical intervention on the dilated aorta, particularly the ascending segment. Studies of the natural history of ascending aortic aneurysms indicate that aneurysms exceeding 6 cm in maximum diameter are associated with a particularly high risk of complications. In the interest of providing some margin of safety, most surgeons would agree that intervention is indicated with an aortic diameter of 5.5 cm. Many would intervene even earlier (at 5.0 cm) for patients at low surgical risk, or for those with known connective tissue disorders such as Marfan's syndrome. In some cases, only the ascending aortic segment needs to be treated, while in others full root replacement is required. Reduction aortoplasty has been superseded largely by interposition graft replacement. The standard procedure involves replacement of the valve and root with a composite mechanical conduit or tissue root prosthesis, and results are excellent. Recently developed valve-sparing root reconstructive options, however, are promising and have encouraged an even more aggressive surgical stance.  相似文献   
40.
In order to obtain functional parameters relevant to the designing of a subretinal implant, we carried out electrical stimulation experiments with isolated chicken retina. The median threshold for network activation with planar disc electrodes (diameter 10 microm) was 0.5 nC (625 microC cm(-2)) for anodal voltage impulses and 1.6 nC (2 mC cm(-2)) for cathodal impulses. Above threshold, the number of spikes evoked by a single voltage impulse increased up to saturation within a range of injected charge from 0.1 nC to 1 nC for anodal impulses and from 1 nC to 10 nC for cathodal impulses. Using needle electrodes with a tip diameter of 1 microm, we determined the electrical point spread function (EPSF) for subretinal stimulation. It had a half width in the range of 100 microm, which corresponds to a visual angle of 21' and to a visual acuity of 20/417 in the human eye. It is reasonable to conclude that with subretinal implants the minimum separable will be of the same dimension.  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

京公网安备 11010802026262号