全文获取类型
收费全文 | 754篇 |
免费 | 43篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 12篇 |
妇产科学 | 58篇 |
基础医学 | 79篇 |
口腔科学 | 8篇 |
临床医学 | 65篇 |
内科学 | 191篇 |
皮肤病学 | 9篇 |
神经病学 | 23篇 |
特种医学 | 9篇 |
外科学 | 80篇 |
综合类 | 30篇 |
预防医学 | 61篇 |
眼科学 | 24篇 |
药学 | 47篇 |
中国医学 | 2篇 |
肿瘤学 | 104篇 |
出版年
2023年 | 10篇 |
2022年 | 12篇 |
2021年 | 35篇 |
2020年 | 7篇 |
2019年 | 16篇 |
2018年 | 16篇 |
2017年 | 7篇 |
2016年 | 30篇 |
2015年 | 36篇 |
2014年 | 37篇 |
2013年 | 59篇 |
2012年 | 83篇 |
2011年 | 46篇 |
2010年 | 35篇 |
2009年 | 14篇 |
2008年 | 46篇 |
2007年 | 39篇 |
2006年 | 35篇 |
2005年 | 25篇 |
2004年 | 23篇 |
2003年 | 25篇 |
2002年 | 18篇 |
2001年 | 16篇 |
2000年 | 8篇 |
1999年 | 13篇 |
1998年 | 4篇 |
1996年 | 3篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1929年 | 1篇 |
排序方式: 共有803条查询结果,搜索用时 218 毫秒
1.
2.
3.
Analyses of T-cell differentiation from hemopoietic stem cells in the G0 phase by an in vitro method. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
J Toki T Kumamoto H Ogata M Kawamura M Fukumoto Cherry Y Yamamoto S Than M Inaba Y Himeno et al. 《Proceedings of the National Academy of Sciences of the United States of America》1991,88(17):7548-7551
Using differential radiation sensitivity of components of mouse embryonal thymus, an in vitro method for studying T-cell differentiation from hemopoietic stem cells (HSCs) in the G0 phase was established. Intrathymic T-cell precursors present in embryonal thymus were found to be quite radioresistant (up to 20 Gy), and consequently 25-Gy-irradiated embryonal thymic lobes were used. Thymic lobes (25-Gy irradiated) taken from mouse fetuses (gestation day 15) were placed in Millipore-HA culture plates supported on squares of gelatin foam sponge in 24-well culture plates in which neonatal thymus stromal cells were cultured. HSCs (10(5) cells per well) in the G0 phase were added to these thymic lobes and cocultured at 37 degrees C in a 5% CO2/95% air incubator. Half the culture medium was changed every week. After 3 weeks, a large number of colonies had formed. Immunohistochemical studies and fluorescence-activated cell sorter analyses revealed that the colonizing cells regularly develop and exhibit surface markers characteristic of T cells (Thy-1, IL-2R, L3T4, Lyt-2, etc.). In situ hybridization analyses revealed that mRNA expression for T-cell receptor (TCR) beta chains occurred within colonizing cells. Using a monoclonal antibody (F23.1), expression of TCR beta-chain variable domain (V beta 8) on the surface of these developing T cells was demonstrated. These cells responded to interleukin 2 and/or anti-CD3 monoclonal antibody, indicating functional T cells. This method will be useful in studying T-cell differentiation pathways from pluripotent HSCs and in clarifying the mechanisms involved in negative and positive selection of T cells within the thymus. 相似文献
4.
Monochloramine derivatives are physiological oxidants produced by activated neutrophils. We report the effects of chemically prepared monochloramine (NH2Cl) on Fas-induced apoptosis in Jurkat T cells. When the cells were pretreated with NH2Cl (20-70 microM), subsequent addition of apoptosis-inducing anti-Fas antibody resulted in a synergistic enhancement of apoptosis. Treatment of NH2Cl (50-70 microM) alone resulted in a slight but definite apoptosis. Caspase activities, as measured by DEVD and IETD cleavage activities, were also elevated synergistically by NH2Cl + anti-Fas antibody stimulation. Moreover, a broad caspase inhibitor, Z-VAD-fmk, almost completely inhibited the apoptosis induced by NH2Cl and/or anti-Fas antibody. Fas expression on the Jurkat cell surface was not affected by the NH2Cl treatment. After 3 h of NH2Cl treatment, when the apoptosis was beginning to increase, the cells showed cytochrome c release from mitochondria, proteolytic activation of caspase 9, and poly (ADP-ribose) polymerase cleavage, regardless of Fas stimulation. Z-VAD-fmk almost completely inhibited this poly (ADP-ribose) polymerase cleavage, but not cytochrome c release. By contrast, Fas stimulation alone resulted in neither cytochrome c release nor caspase 9 activation at 3 h, and the increase in the DEVD cleavage activity and apoptosis became evident at later time points. These results suggested that NH2Cl enhanced Fas-induced apoptosis through the cytochrome c release and caspase 9 activation at the early stage of apoptosis. Chloramines derived from acute inflammation may modify immune reactions, such as cell-mediated cytotoxicity and some autoimmune diseases, by the enhancement of Fas-induced apoptosis. 相似文献
5.
Apoptosis of colorectal adenocarcinoma (COLO 201) by tumour necrosis factor-alpha (TNF-α) and/or interferon-gamma (IFN-γ), resulting from down-modulation of Bcl-2 expression
下载免费PDF全文
![点击此处可从《Clinical and experimental immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Koshiji Adachi Sogo Taketani Oyaizu Than Inaba Phawa Hioki Ikehara 《Clinical and experimental immunology》1998,111(1):211-218
Fas antigen is constitutively expressed in the normal colon epithelium, but considerably diminished in most colorectal carcinomas. In the present study, we examine the relationship between Fas antigen expression and apoptosis using the colorectal carcinoma cell line COLO 201, on which a low grade of Fas antigen is expressed. Anti-Fas antibody had no effect on the induction of apoptosis of COLO 201. However, TNF-α and/or IFN-γ, independently and additively, up-regulated Fas antigen expression on COLO 201 and induced apoptosis in a dose-dependent manner. Both cytokines also increased the COLO 201 sensitivity to anti-Fas antibody, resulting from the down-modulation of Bcl-2 and the up-regulation of Bax. These findings indicate that cytokine(s) plus anti-Fas antibody (which mimics natural Fas ligand) are more effective in inducing apoptosis of COLO 201 than cytokine(s) alone. These findings suggest that immunotherapy in combination with cytokine(s) and lymphokine-activated killer (LAK) cells will become a more effective therapy for cancer than cytokine(s) or LAK cells alone, since the Fas ligand is expressed on activated T cells, natural killer cells and macrophages. 相似文献
6.
何首乌组织培养的研究 总被引:10,自引:0,他引:10
采用单因子、正交设计法考察了基本培养基、激素以及光暗条件对何首乌幼嫩茎、叶诱导愈伤组织的影响,以及培养时间与愈伤组织生长量间的关系。实验研究表明:MS 2,4D1mg/L 6-BA1mg/L IBA0.5mg/L和暗培养对诱导何首乌愈伤组织产生效果较好;接种12天时愈伤组织生长量达到最大;愈伤组织经诱导能够产生完整植株,成苗率为95%。 相似文献
7.
8.
Manojkumar Bupathi Ahmed Kaseb Funda Meric-Bernstam Aung Naing 《Molecular oncology》2015,9(8):1501-1509
Hepatocellular carcinoma (HCC) is a complex and heterogeneous tumor most commonly associated with underlying chronic liver disease, especially hepatitis. It is a growing problem in the United States and worldwide. There are two potential ways to prevent HCC. Primary prevention which is based on vaccination or secondary prevention involving agents that slow down carcinogenesis. Several pathways have been thought to play a role in the development of HCC; specifically, those involving vascular endothelial growth factor (VEGF)‐mediated angiogenesis, WNT, phosphatidylinositol 3‐kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR), AMP‐activated protein kinase (AMPK), and c‐MET. Currently, there are only a limited number of drugs which have been proven as effective treatment options for HCC and several clinical trials are testing drugs which target aberrations in the pathways mentioned above. In this review, we discuss currently approved therapies, monotherapies and combination therapy for the treatment of HCC. 相似文献
9.
10.
Nivedita Sharma Than Singh Tomar Arun Peter Mathew K. Chandramohan R. Preethi Rari P. Mony 《The Indian journal of surgery》2017,79(6):571-573
Aggressive angiomyxoma (AAM) is a rare mesenchymal tumour of pelvis and perineum, almost exclusively occurring in females. We are reporting a case of a 53-year-old gentleman who presented with a long standing inguinoscrotal swelling misdiagnosed as inguinal hernia, for which he underwent incomplete excision at local hospital and then was referred to our centre for completion surgery. 相似文献