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   284篇
  免费   18篇
  国内免费   13篇
耳鼻咽喉   1篇
儿科学   21篇
妇产科学   5篇
基础医学   25篇
口腔科学   7篇
临床医学   28篇
内科学   76篇
皮肤病学   3篇
神经病学   11篇
特种医学   64篇
外科学   14篇
综合类   9篇
预防医学   5篇
药学   8篇
肿瘤学   38篇
  2024年   1篇
  2022年   2篇
  2021年   2篇
  2020年   3篇
  2019年   2篇
  2018年   3篇
  2017年   3篇
  2016年   5篇
  2015年   4篇
  2014年   9篇
  2013年   5篇
  2012年   5篇
  2011年   6篇
  2010年   12篇
  2009年   13篇
  2008年   7篇
  2007年   11篇
  2006年   2篇
  2005年   4篇
  2004年   3篇
  2003年   10篇
  2002年   2篇
  2001年   6篇
  2000年   5篇
  1999年   4篇
  1998年   16篇
  1997年   12篇
  1996年   12篇
  1995年   11篇
  1994年   17篇
  1993年   13篇
  1992年   4篇
  1991年   4篇
  1990年   6篇
  1989年   13篇
  1988年   11篇
  1987年   11篇
  1986年   7篇
  1985年   6篇
  1984年   5篇
  1983年   7篇
  1982年   4篇
  1981年   7篇
  1980年   4篇
  1979年   2篇
  1978年   6篇
  1977年   3篇
  1976年   4篇
  1974年   1篇
排序方式: 共有315条查询结果,搜索用时 171 毫秒
91.
92.
93.
Amplification of the neu proto-oncogene in breast cancer has been reported to correlate with the presence of lymph-node metastases and with a poor prognosis. We describe a method for the immunohistochemical detection of overexpression of neu protein on formalin-fixed paraffin-embedded tissue, with the use of two different monoclonal antibodies. In a group of tumors with a known neu-gene copy number, intense membrane staining of tumor cells was present in all tumors with neu-gene amplification. Of 189 tumors from patients with Stage II breast cancer, 27 (14 percent) had neu-membrane staining. Neu overexpression was associated with larger tumor size (P = 0.006) but not with lymph-node involvement. Neu-protein expression in lymph-node metastases was the same as its expression in primary tumors. Among the patients with neu overexpression (median follow-up, 37 months), disease-free survival was not significantly shorter; overall survival was reduced significantly in these patients (P = 0.042), but this reduction did not remain significant after adjustment for tumor size. Of 45 ductal carcinomas in situ, 19 (42 percent) had neu-membrane staining. These 19 were all of the large-cell, comedo growth type. None of 16 ductal carcinomas in situ of small-cell, papillary, or cribriform growth type had neu overexpression. We conclude that neu overexpression may be an early step in the development of a distinct histologic type of carcinoma of the breast, but we could find no association of overexpression with lymph-node status or tumor recurrence.  相似文献   
94.
P-31 MR spectroscopy of normal human brain and brain tumors   总被引:2,自引:0,他引:2  
Image-guided phosphorus-31 magnetic resonance (MR)-localized image-selected in vivo spectroscopy was performed on normal human brain and brain tumors. Peak area ratios, absolute molar concentrations of metabolites, and pH were determined. T1 values in normal brain were measured. The most important finding was that the metabolite concentrations detectable with MR spectroscopy in brain tumors were reduced from 20% to 70%. Phosphomonoesters, phosphodiesters, and phosphocreatine (PCr) showed the greatest decreases, while inorganic phosphate (Pi) showed the least change. The PCr-Pi ratio was significantly reduced in tumors. The pH of brain tumors (7.12 +/- 0.03) was more alkaline than that of normal brain (6.99 +/- 0.01). The authors conclude that the metabolite concentrations and pH in human brain tumors differ significantly from those in normal brain. These differences may be ultimately useful in characterizing tumors in man.  相似文献   
95.
问题:在出生后的最初5年,减少房屋尘螨(HDM)变应原暴露并改变饮食中脂肪酸构成是否可以降低5岁时发生哮喘的风险?  相似文献   
96.
BACKGROUND: Telomerase activation is thought to be essential for the immortality of cancer cells. It may be a prognostic factor in small volume well differentiated prostate cancers and hence a guide for the aggressiveness of the approach. The length of the chromosome tips (telomeres) are maintained by a specific enzyme (telomerase) independently of the normal cell division cycle. Although telomerase is not expressed in most normal human tissues, it is expressed in most human tumours. For the detection of telomerase in small prostate needle biopsy samples a recently developed telomeric repeat amplification protocol (TRAP) assay was used. The aim of the present study was: to measure telomerase activity in human prostate samples, and to evaluate the applicability of this assay on specimens from a prostate biopsy. MATERIALS AND METHODS: From 36 patients referred for lower urinary tract symptoms (LUTS) or suspicion of having prostate cancer a total of 288 prostate biopsy samples were obtained (8 in each patient). When the digital rectal examination was abnormal and/or when the PSA level was elevated in L.U.T.S., or asymptomatic patients' tissue samples were obtained by transrectal ultrasound (TRUS) guided biopsies. Samples were tested for telomerase activity by a modified TRAP and forwarded for histology. RESULTS: In 19 out of 36 patients prostate cancer was diagnosed on histology. In 11 of these 19 tumours substantial telomerase activity was detected, whereas only very low telomerase activity existed in 2 of 17 samples from benign prostatic hypertrophy (BPH) patients. In this small series the relative telomerase activity in prostate cancer correlated with histopathological grade. CONCLUSIONS: Our results show the applicability of a TRAP assay to measure telomerase activity in small needle biopsied prostate samples. In poorly differentiated and metastatic cancer we observed that levels of telomerase activity were high. To establish accuracy and to distinguish the 'relative good from the ugly' further study is needed.  相似文献   
97.
98.
99.
Histiocytic medullary reticulosis in childhood   总被引:2,自引:0,他引:2  
Gilsanz  V; Harris  GB 《Radiology》1978,126(2):463
  相似文献   
100.
Edge enhancement of ECG-gated cardiac images using directional masks   总被引:1,自引:0,他引:1  
Kan  MK; Hopkins  GB 《Radiology》1978,127(2):525-528
ECG-gated images were processed by a computer using a nonlinear digital filter and directional masks to improve delineation of cardiac chamber boundaries and identification of the aortic and mitral valve planes. This technique proved to be satisfactory in 30 patients with documented coronary or valvular heart disease.  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