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   504篇
  免费   34篇
  国内免费   6篇
耳鼻咽喉   2篇
儿科学   51篇
妇产科学   6篇
基础医学   80篇
口腔科学   8篇
临床医学   25篇
内科学   89篇
皮肤病学   14篇
神经病学   8篇
特种医学   58篇
外科学   40篇
综合类   81篇
预防医学   15篇
眼科学   6篇
药学   15篇
中国医学   1篇
肿瘤学   45篇
  2023年   1篇
  2021年   1篇
  2020年   1篇
  2019年   5篇
  2018年   6篇
  2017年   3篇
  2016年   4篇
  2015年   11篇
  2014年   14篇
  2013年   13篇
  2012年   8篇
  2011年   13篇
  2010年   20篇
  2009年   29篇
  2008年   16篇
  2007年   17篇
  2006年   12篇
  2005年   9篇
  2004年   11篇
  2003年   23篇
  2002年   18篇
  2001年   26篇
  2000年   25篇
  1999年   29篇
  1998年   46篇
  1997年   21篇
  1996年   27篇
  1995年   14篇
  1994年   23篇
  1993年   14篇
  1992年   3篇
  1991年   7篇
  1990年   5篇
  1989年   7篇
  1988年   7篇
  1987年   2篇
  1986年   5篇
  1985年   7篇
  1984年   6篇
  1983年   2篇
  1982年   3篇
  1981年   2篇
  1980年   7篇
  1978年   4篇
  1977年   5篇
  1976年   7篇
  1975年   3篇
  1974年   1篇
  1970年   1篇
排序方式: 共有544条查询结果,搜索用时 15 毫秒
1.
The clinical course of malignant melanomas is frequently unpredictable, although a number of prognostically useful variables can be identified. There is a need for additional markers of prognostic value. In a series of 60 malignant cutaneous melanomas, we analysed the immunohistochemical expression of c-myc proto-oncogene, heat shock protein 70 (HSP70) and HLA-DR molecules in order to investigate their prognostic significance. C-myc, HSP70 and HLA-DR were expressed in 43.3%, 56.6% and 38.3% of all melanoma cases, respectively. Advanced Clark levels (Clark III–V) were significantly associated with c-myc expression rate (P<0.05), HSP70 detection (P<0.01) and HLA-DR positivity (P<0.01). Increased Breslow thickness (>1.5 mm) was related to HLA-DR expression (P<0.05). High mitotic rate was closely associated with c-myc positivity (P<0.05), while HSP70 and HLA-DR expression separately correlated to clinical stage of the disease (P<0.05). The evaluation of these variables may be of immunological and prognostic significance. They were found to be associated with melanocyte subpopulations of the vertical growth phase which are arguably characterized by an increased invasive potential.  相似文献   
2.
Background. Extensive questioning of patients with a wide variety of skin disorders led to the impression that nocturnal overheating was probably an important factor in the initiation and the perpetuation of many skin disorders. Methods. In order to test the hypothesis, 12 “clean-skinned” subjects (6M/6F) aged 18 to 45 years were monitored electronically every 30 seconds during an 8 hour sleep period (2300 to 0700 hours), sleeping under a standard 10 tog duvet. Results. All the subjects were too hot by 3 to 4°C. All showed changes in their EEG patterns with reduced REM sleep, increased awakenings, and all showed changes in their sleep stage patterns. In addition, they all showed evidence of increased sweating in the “heat-sink” area. Conclusions. The mechanisms where by such changes could be implicated in the precipitation and perpetuation of skin disease are discussed. “Lifestyle” modification as a very effective, noninvasive, therapeutic regime is recommended. Further research along these lines would probably be very valuable and instructive.  相似文献   
3.
4.
5.
6.
7.
Breast carcinoma is a genetically and phenotypically heterogeneous disease and is frequently associated with nonrandom chromosomal alterations. The aim of this study was to investigate the numerical aberrations of chromosome 20 in breast cancer. The observed chromosome-specific numerical abnormalities were evaluated along with the established clinicopathological parameters, the immunohistochemical expression of ER, PR, p53, c-erbB-2, Ki-67 and patients' survival. Nonisotopic in situ hybridization was applied to interphase cell nuclei on paraffin embedded tissue sections. Polysomy of chromosome 20 was the prevalent alteration in 45 of 50 (90%), monosomy in 2 of 50 (4%) and disomy in 3 of 50 (6%) cases. Invasive ductal carcinomas displayed a higher percentage of polysomy than lobular ones. A statistical significant association was demonstrated between Ki-67 immunohistochemical expression and polysomy of chromosome 20. Disomy was inversely correlated with Ki-67, while monosomy was suggestively associated with PR positive expression. Among the patients, those with the highest levels of polysomy showed the worst survival. In conclusion, the gain of chromosome 20 is the prevalent aberration in patients with breast carcinomas and may be useful prognostic marker in breast cancer.  相似文献   
8.
Fifty-two intracranial, totally excised meningiomas were immunohistochemically analysed for the expression of bcl-2 and p53 proteins, in parallel with the assessment of the proliferating cell nuclear antigen labelling index (PCNA LI) and the mitotic index (MI). bcl-2 was expressed in 26.8 per cent and p53 in 32.6 per cent of the tumours, exhibiting a similar staining pattern, with low levels of immunoreactive cells. The bcl-2-positive/p53-negative subgroup showed a significant association with a benign histological pattern. Expression of bcl-2 appeared to have no influence on the rate of recurrence; p53 expression was the only factor with prognostic significance for recurrence (p = 0.10). There was no interaction between bcl-2 and p53 expression. The PCNA LI was correlated with the MI and the grade of malignancy, proving to be a useful proliferation marker and an additional indicator of the more anaplastic histological patterns in meningiomas. Proliferation indices appeared to have no correlation with the recurrence rate of totally resected tumours. Meningiomas expressing the bcl-2 protein presented a high proportion of proliferating cells in S phase. In contrast, all the tumours which recurred had a minimal S-fraction of proliferating nuclei. These findings may improve our understanding of the interaction between cell proliferation, expression of apoptotic markers, and recurrence in meningiomas.  相似文献   
9.
Roberts syndrome (RS) is a rare autosomal recessive disorder characterized primarily by symmetric reduction anomalies of all limbs, growth retardation and craniofacial abnormalities. Most RS patients are reported to present a typical abnormality of their constitutive heterochromatin, accompanied by abnormal cytological growth characteristics. We present an extremely severe case of an RS fetus, karyotypically documented, with a clinical presentation including growth deficiency, tetraphocomelia, frontal meningocele, craniofacial abnormalities and penile enlargement with hypospadias. Nuclear morphometrical analysis in tissues of various organs revealed a reduced nuclear size in RS as compared to normal controls, and statistically significant differences in morphometric parameters related to the nuclear shape. Immunohistochemical study of the same organs showed a reduced expression of proliferating cell nuclear antigen in the presented case, thus indicating a decreased cell proliferation rate in RS. Our results reconfirm previously reported findings in cultured fibroblasts of RS cases, thereby reinforcing on a histologic level, the hypothesis that reduced cell proliferation may be involved in the growth retardation and the reduction abnormalities observed in RS.  相似文献   
10.

Background  

Inflammation and immune responses are considered to be very important in the pathogenesis of atherosclerosis. Lipid accumulation in macrophages of the arterial intima is a characteristic feature of atherosclerosis which can influence the inflammatory potential of macrophages. We studied the effects of lipid loading on the regulation of TNF expression in human monocyte-derived macrophages.  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