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   328篇
  免费   13篇
耳鼻咽喉   1篇
妇产科学   2篇
基础医学   49篇
口腔科学   19篇
临床医学   19篇
内科学   95篇
皮肤病学   1篇
神经病学   4篇
特种医学   9篇
外科学   25篇
综合类   3篇
预防医学   45篇
药学   17篇
肿瘤学   52篇
  2023年   2篇
  2022年   2篇
  2021年   5篇
  2020年   4篇
  2019年   5篇
  2016年   3篇
  2015年   5篇
  2014年   4篇
  2013年   6篇
  2012年   7篇
  2011年   7篇
  2010年   5篇
  2009年   7篇
  2008年   15篇
  2007年   22篇
  2006年   18篇
  2005年   16篇
  2004年   18篇
  2003年   22篇
  2002年   21篇
  2001年   22篇
  2000年   21篇
  1999年   15篇
  1998年   8篇
  1997年   5篇
  1996年   2篇
  1995年   4篇
  1994年   2篇
  1992年   2篇
  1991年   5篇
  1990年   8篇
  1989年   7篇
  1988年   8篇
  1987年   4篇
  1986年   5篇
  1985年   3篇
  1984年   4篇
  1983年   3篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1978年   3篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1973年   3篇
  1972年   1篇
  1971年   1篇
  1969年   2篇
  1968年   3篇
排序方式: 共有341条查询结果,搜索用时 15 毫秒
1.
Syphilis is a sexually transmitted disease caused by Treponema pallidum. Syphilitic aortitis might coexist in a dysfunctional aortic valve, but the etiology remains unclear, because microbiological diagnosis is difficult. A 62-year-old man with low-grade fever was diagnosed with aortitis and infective endocarditis, due to Treponema pallidum infection, using polymerase chain reaction analysis. This case suggests that syphilis might cause infective endocarditis.  相似文献   
2.
Abnormal DNA content has been considered as an additional criterion for determining the biological behavior of a tumor. Flowcytometric DNA analysis was done on 121 patients with thyroid carcinoma encountered during the period between 1975 and 1987. Tumor tissues were sampled from paraffin-embedded blocks and the histology of thyroid carcinoma found to consist of 91 papillary, 23 follicular, 2 medullary, 1 squamous cell and 4 anaplastic carcinomas. The incidence of aneuploidy in thyroid carcinoma was 7.4 per cent (9 patients) while that of diploidy was 92.6 per cent (112 patients). The aneuploid specimens consisted of 6 papillary, 1 follicular, 1 medullary and 1 anaplastic carcinomas and, of 4 anaplastic carcinoma patients with subsequent death within 6 months, only 1 was aneuploid. As an indicator of proliferative potential, S-phase fraction (SPF) was also determined by flow cytometry, but this could not be used as an independent prognostic factor. The aneuploid patients showed a significantly decreased survival rate (p less than 0.01). Thus, although DNA measurement proved useful for predicting the survival of aneuploid patients, there is some discrepancy between DNA content and the biological behavior of the tumor.  相似文献   
3.
Transformation of a rat cell line by an adenovirus 7 DNA fragment   总被引:13,自引:0,他引:13  
A clonal rat embryo cell line, 3Y1, was transformed by the HindIII-I·J fragment of adenovirus 7 DNA (left 8.1% of whole Adz DNA), one of the partial digestion products with HindIII, and by whole Ad7 DNA. Most, if not all, of the nucleotide sequences of the HindIII-I·J fragment were present in cells transformed by Ad7 HindIII-I·J fragment, whereas approximately the left two thirds of the viral DNA genome was present in cells transformed by Ad7 whole DNA. These results indicate that the transforming gene of adenovirus 7 is located in HindIII-I·J fragment and is mapped at the left 8% end of the adenovirus 7 genome.  相似文献   
4.
Summary We used the nude mouse tumour xenograft model to study the pathogenesis of mucosa alterations in the large bowel surrounding a carcinoma. In mouse colonic mucosa overlying HT-29 colonic carcinoma xenografts in the caecum, the crypts were elongated in comparison with those in distant mucosa and also frequently showed a shift towards sialomucin production. These features, which are comparable with socalled transitional mucosa (TM) in man, were absent in control animals inoculated with Indian Ink instead of HT-29 cells. Although the localization of the proliferative cell compartment in mouse colonic mucosa overlying HT-29 xenografts appeared to be confined to the lower half of the crypt as in normal mucosa, the relative length of the DNA synthesizing cell compartment along the crypts was slightly elongated. These data strongly suggest that TM should be regarded as a secondary phenomenon rather than a premalignant change in large intestinal epithelium and that higher proliferative activity of epithelial cells contributes little to the elongation of crypts in TM.  相似文献   
5.
6.
We report a case of ductal carcinoma in situ (DCIS) of the breast detected by ultrasonographic mass screening in a 51-year-old woman. In a mass screening program for breast cancer, physical examination with inspection and palpation, and ultrasonography (US) were performed. A hypoechoic mass with a slightly irregular margin was detected by US in the lateral upper quadrant of the right breast, at a distance 2 cm from the edge of the nipple. The mass was not detected by physical examinations or by mammography (MMG). The mass, which measured 0.8 x 0.5 cm and was examined by fine needle aspiration biopsy (FNAB) under US guidance, was cytologically diagnosed as class X. Modified radical mastectomy (Auchincloss method) was performed with the patient's consent. Pathological examination of the resected specimen revealed DCIS (noncomedo type) and occult multiple foci of malignancy which was considered tracking centripetally underneath the nipple. This case suggests that US and FNAB performed under US guidance are useful in the detection and diagnosis, respectively, of a breast mass. We should take multifocality into consideration, particularly with tendency tracking to the nipple, in the treatment of small breast cancers such as DCIS.  相似文献   
7.
8.
9.
GeroScience - Apolipoprotein E (APOE) allelic variation is associated with differences in overall circulating lipids and risks of major health outcomes. Lipid profiling provides the opportunity for...  相似文献   
10.
We have investigated the requirement of the signal sequence for expression of influenza virus hemagglutinin (HA). For this purpose we used a recombinant prepared from a late-region deletion mutant of simian virus 40 (SV40) and cloned influenza HA DNA; the influenza DNA was inserted into the late region of SV40 previously occupied by the deleted sequences coding for SV40 capsid proteins. A simple in-phase deletion was made in the HA DNA, resulting in loss of 11 internal amino acids from the 16 amino acid signal peptide. This deletion HA recombinant was then used to infect African green monkey kidney cells. Mutant HA was not detected on the cell surface but stably accumulated in the cytoplasm at a level similar to that of wild-type HA. NaDodSO4/polyacrylamide gel analysis of lysates from infected cells showed that mutant HA was not glycosylated. Significantly, the amount of mutant HA synthesized was not affected by tunicamycin. In contrast, wild-type HA was decreased more than 90% by tunicamycin. These findings suggest that mutant polypeptide is synthesized on free polyribosomes rather than on membrane-bound polyribosomes. The mutant HA failed to agglutinate erythrocytes, probably due to a defect directly or indirectly associated with the lack of carbohydrate side chains.  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