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   18695篇
  免费   1266篇
  国内免费   74篇
耳鼻咽喉   216篇
儿科学   419篇
妇产科学   345篇
基础医学   2583篇
口腔科学   318篇
临床医学   1618篇
内科学   4829篇
皮肤病学   410篇
神经病学   1618篇
特种医学   613篇
外科学   2653篇
综合类   238篇
一般理论   8篇
预防医学   1394篇
眼科学   411篇
药学   1113篇
中国医学   77篇
肿瘤学   1172篇
  2023年   131篇
  2022年   329篇
  2021年   545篇
  2020年   306篇
  2019年   449篇
  2018年   516篇
  2017年   342篇
  2016年   364篇
  2015年   449篇
  2014年   619篇
  2013年   838篇
  2012年   1331篇
  2011年   1347篇
  2010年   773篇
  2009年   664篇
  2008年   1125篇
  2007年   1194篇
  2006年   1175篇
  2005年   1105篇
  2004年   1007篇
  2003年   959篇
  2002年   952篇
  2001年   132篇
  2000年   117篇
  1999年   160篇
  1998年   198篇
  1997年   164篇
  1996年   164篇
  1995年   120篇
  1994年   115篇
  1993年   98篇
  1992年   100篇
  1991年   99篇
  1990年   88篇
  1989年   69篇
  1988年   79篇
  1987年   83篇
  1986年   66篇
  1985年   87篇
  1984年   97篇
  1983年   92篇
  1982年   110篇
  1981年   123篇
  1980年   107篇
  1979年   64篇
  1978年   74篇
  1977年   87篇
  1976年   61篇
  1974年   52篇
  1973年   48篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Malignant mesothelioma (MM) is associated with asbestos exposure and the presence of SV40 viral sequences. Recently, we reported that SV40 infection of human mesothelial cells (HM) causes aberrant methylation of the tumor suppressor gene (TSG) RASSF1A. We investigated methylation of 12 genes by methylation-specific PCR in 63 MMs, six MM cell lines, and two foci of SV40-infected HM. Methylation percentages of the tested genes ranged from 3 to 65%. The frequencies of HPP1, RASSF1A, Cyclin D2, and RRAD methylation, and the value of the methylation index, were significantly higher in SV40 sequence-positive MMs than in SV40-negative MMs. Methylation of TMS1 and HIC-1 was associated with shortened survival. SV40-infected HM showed progressive aberrant methylation of seven genes (RASSF1A, HPP1, DcR1, TMS1, CRBP1, HIC-1, and RRAD) during serial passage. Our results demonstrate a relationship between SV40 and methylation of multiple genes in MM, indicating that the virus plays a role in the pathogenesis of MM.  相似文献   
992.
Cancer reflects the progressive accumulation of genetic alterations and subsequent genetic instability of cells. Cytogenetic studies have demonstrated the importance of aneuploidy in differentiated thyroid cancer development. The pituitary tumour transforming gene (PTTG), also known as securin, is a mitotic checkpoint protein which inhibits sister chromatid separation during mitosis. PTTG is highly expressed in many cancers and overexpression of PTTG induces aneuploidy in vitro. Using fluorescent intersimple sequence repeat PCR (FISSR-PCR), we investigated the relationship between PTTG expression and the degree of genetic instability in normal and tumorous thyroid samples. The genomic instability index (GI index) was 6.7-72.7% higher in cancers than normal thyroid tissues. Follicular thyroid tumours exhibited greater genetic instability than papillary tumours (27.6% (n=9) versus 14.5% (n=10), P=0.03). We also demonstrated a strong relationship between PTTG expression and the degree of genetic instability in thyroid cancers (R2=0.80, P=0.007). To further investigate PTTG's role in genetic instability, we transfected FTC133 thyroid follicular cells and observed increased genetic instability in cells overexpressing PTTG compared with vector-only-transfected controls (n=3, GI Index VO=29.7+/-5.2 versus PTTG=63.7+/-6.4, P=0.013). Further, we observed a dose response in genetic instability and PTTG expression (GI Index low dose (0.5 microg DNA/ six-well plate) PTTG=15.3%+/-1.7 versus high dose (3 microg DNA) PTTG=50.8%+/-3.3, P=0.006). Overall, we describe the first use of FISSR-PCR in human cancers, and demonstrate that PTTG expression correlates with genetic instability in vivo, and induces genetic instability in vitro. We conclude that PTTG may be an important gene in the mutator phenotype development in thyroid cancer.  相似文献   
993.
994.
995.
996.
997.
998.
Anorexia and appetite assessment is an important priority in supportive oncology. A series of 156 veterans participating in a hematology oncology service completed the Functional Assessment of Anorexia/Cachexia Therapy (FAACT), the Functional Assessment of Cancer Therapy-General scale, the Memorial Symptom Assessment Scale Short Form (MSAS-SF), and the Zung Self-Rating Depression Scale and were followed for survival. The FAACT score correlated well with Karnofsky performance status, quality of life, and symptom distress subscales. A single appetite distress item from the MSAS-SF correlated well with these measures. Both appetite measures correlated with the presence of other symptoms and with concurrently measured hemoglobin, serum sodium, albumin, and cholesterol levels. These self-reported appetite measures were univariate predictors of survival and contributed additional prognostic information to data related to weight-loss distress. In a smaller study, the FAACT score correlated with a visual analogue measure of appetite and with the North Center Cancer Treatment Group appetite instrument.These data support use of these tools for the evaluation of appetite concerns among patients with advanced cancer.  相似文献   
999.
Role of free radicals in sepsis: antioxidant therapy   总被引:6,自引:0,他引:6  
  相似文献   
1000.
Pulmonary fibrosis is often the end stage of chronic, persistent, low-level lung injury, either of known or unknown cause. The most severe form of pulmonary fibrosis is idiopathic pulmonary fibrosis (IPF), a disease process of unknown aetiology and one that often leads to respiratory failure and death. At present there are no proven or effective drug therapies for IPF. Recent advances in understanding of disease pathogenesis have focused attention on drug targeting of fibrogenic pathways, as opposed to traditional anti-inflammatory approaches. In this report, the present status of drug development of a number of emerging antifibrotic strategies and agents that may prove more effective in the therapy of this progressive, debilitating and fatal disease are reviewed.  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