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   1510篇
  免费   75篇
  国内免费   17篇
耳鼻咽喉   10篇
儿科学   6篇
妇产科学   17篇
基础医学   150篇
口腔科学   18篇
临床医学   114篇
内科学   497篇
皮肤病学   18篇
神经病学   69篇
特种医学   85篇
外科学   216篇
综合类   10篇
预防医学   71篇
眼科学   8篇
药学   69篇
中国医学   5篇
肿瘤学   239篇
  2023年   7篇
  2022年   11篇
  2021年   32篇
  2020年   12篇
  2019年   22篇
  2018年   32篇
  2017年   25篇
  2016年   39篇
  2015年   34篇
  2014年   30篇
  2013年   51篇
  2012年   84篇
  2011年   117篇
  2010年   56篇
  2009年   37篇
  2008年   82篇
  2007年   94篇
  2006年   86篇
  2005年   66篇
  2004年   78篇
  2003年   64篇
  2002年   71篇
  2001年   41篇
  2000年   53篇
  1999年   48篇
  1998年   15篇
  1997年   22篇
  1996年   8篇
  1995年   9篇
  1994年   8篇
  1993年   6篇
  1992年   32篇
  1991年   23篇
  1990年   29篇
  1989年   23篇
  1988年   18篇
  1987年   19篇
  1986年   15篇
  1985年   20篇
  1984年   11篇
  1983年   5篇
  1981年   4篇
  1980年   5篇
  1979年   10篇
  1978年   12篇
  1974年   7篇
  1971年   3篇
  1969年   6篇
  1968年   3篇
  1967年   5篇
排序方式: 共有1602条查询结果,搜索用时 328 毫秒
101.
We report an 82-year-old Japanese woman with basal cell carcinoma of the left nipple and areola extending into the lactiferous duct. The patient developed a small papular lesion of the left areola about 1 year before admission. The lesion, which had slowly progressed to involve the nipple, had become symptomatic showing weeping and bleeding. Mammography revealed microcalcification in the nipple. Although Paget's disease was suspected from these clinical features, histologically basal cell carcinoma was diagnosed. There was no axillary lymphadenopathy, and no evidence of distant metastasis. The lesion of the nipple and areola was resected with a 2 cm free margin along with the underlying mammary tissue. The patient has remained well without signs of recurrence for 2 years after surgery. We reviewed cases of basal cell carcinoma of the nipple or areola and discuss considerations and problems of this rare tumor.  相似文献   
102.
To determine the biological role of caudal-like homeobox gene CDX2, we constructed knockout mice in which its mouse homologue Cdx2 was inactivated by homologous recombination, placing a bacterial lacZ gene under the control of the Cdx2 promoter. Although the homozygous mutants died in utero around implantation, the heterozygotes were viable and fertile and expressed lacZ in the caudal region in early embryos and in the gut tissues in adults. The heterozygotes developed cecal and colonic villi by anteriorization and formed hamartomatous polyps in the proximal colon. The hamartoma started to develop at 11.5 days of gestation as an outpocket of the gut epithelium, which ceased to express the remaining Cdx2 allele. The outpocket then expanded as a partially duplicated gut but was contained as a hamartoma after birth. In adult mice, these hamartomas grew very slowly and took a benign course. None of them progressed into invasive adenocarcinomas, even at 1.5 years of age. Whereas the cecal and colonic villi expressed lacZ, the hamartoma epithelium did not, nor did it express Cdx2 mRNA from the wild-type allele. However, genomic DNA analysis of the polyp epithelium did not show a loss of heterozygosity of the Cdx2 gene, suggesting a mechanism of biallelic Cdx2 inactivation other than loss of heterozygosity. These results indicate that the Cdx2 haploin-sufficiency caused cecal and colonic villi, whereas the biallelic inactivation of Cdx2 triggered anomalous duplications of the embryonic gut epithelium, which were contained as hamartomas after birth.  相似文献   
103.
Gastric and duodenal polyps in Smad4 (Dpc4) knockout mice   总被引:12,自引:0,他引:12  
The SMAD4 (DPC4) gene was initially isolated as a candidate tumor suppressor from the convergent site of homozygous deletions on 18q in a panel of pancreatic carcinoma cell lines. It encodes a common cytoplasmic signaling molecule shared by the transforming growth factor-beta, activin, and bone morphogenic pathways. We recently inactivated its mouse homologue Smad4 and demonstrated its role in the malignant progression of benign adenomas to invasive adenocarcinomas by analyzing mice with Apc and Smad4 compound mutations. Although simple Smad4 homozygotes were embryonically lethal, the heterozygotes were fertile and appeared normal up to the age of 1 year. Upon further investigation, however, they have developed inflammatory polyps in the glandular stomach and duodenum. By PCR genotyping and immunohistochemical staining, the wild-type Smad4 allele has been lost in the polyp epithelial cells, ie., loss of heterozygosity. On the other hand, we have not found any mutations in such genes as K-Ras, H-Ras, N-Ras, p53, or PTEN. Histologically, the polyps are similar to human juvenile polyps showing moderate stromal cell proliferation and infiltrations by eosinophils and plasma cells. In addition, foci of adenocarcinoma with signet ring cells are also found. These results are consistent with a recent report that germ-line SMAD4 mutations are found in a subset of familial juvenile polyposis.  相似文献   
104.
105.
1 (n= 24) and B1 (n= 57), and those with tumors > 8 cm were assigned to groups A2 (n= 20) and B2 (n= 19), respectively. Although no significant differences in survival between groups A1 and B1 were found, group A2 presented superior 1-, 2-, and 3-year tumor-free survival rates of 80%, 55%, and 32% and 1-, 3-, and 5-year cumulative survival rates of 90%, 53%, and 42%. These figures are in comparison with the tumor-free survival rates of 50%, 22%, and 11% (p= 0.06), and the cumulative survival rates of 72%, 33%, and 11% (p= 0.01) during the same periods for group B2, respectively. The Cox regression model revealed that for patients with tumors > 8 cm, the relative risk of preoperative TAE for overall survival was 0.38 (p= 0.017), indicating that preoperative TAE might benefit patients with tumors > 8 cm but not those with tumors 2 to 8 cm.  相似文献   
106.
Of the several types of treatment for cystic hygromas and lymphangiomas, surgical excision has been the preferred treatment. However, there is a high recurrence rate because lymphangiomas tend to infiltrate the surrounding tissues. Bleomycin in a microsphere-in-oil (S/O) emulsion was used in this study as a sclerosing agent for lymphangiomas. Experimental studies using domestic rabbits showed that the bleomycin emulsion caused more marked fibrotic changes at the injection site than other formulations, such as a blank emulsion and bleomycin solution. In clinical trials, 27 of 33 patients received bleomycin S/O emulsion injected directly into the tumors with satisfactory results. Histologic pictures of the clinically resected specimens confirmed the findings of the experimental studies. Comparative studies of treatments between bleomycin S/O emulsion and surgery indicated that injection therapy of bleomycin S/O emulsion would be more beneficial than surgical excisions.  相似文献   
107.
108.
109.
110.
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