全文获取类型
收费全文 | 4977篇 |
免费 | 310篇 |
国内免费 | 457篇 |
出版年
2024年 | 21篇 |
2023年 | 113篇 |
2022年 | 139篇 |
2021年 | 232篇 |
2020年 | 182篇 |
2019年 | 299篇 |
2018年 | 219篇 |
2017年 | 152篇 |
2016年 | 145篇 |
2015年 | 200篇 |
2014年 | 370篇 |
2013年 | 529篇 |
2012年 | 278篇 |
2011年 | 340篇 |
2010年 | 179篇 |
2009年 | 193篇 |
2008年 | 214篇 |
2007年 | 202篇 |
2006年 | 190篇 |
2005年 | 186篇 |
2004年 | 133篇 |
2003年 | 127篇 |
2002年 | 130篇 |
2001年 | 99篇 |
2000年 | 78篇 |
1999年 | 75篇 |
1998年 | 63篇 |
1997年 | 62篇 |
1996年 | 53篇 |
1995年 | 44篇 |
1994年 | 57篇 |
1993年 | 51篇 |
1992年 | 42篇 |
1991年 | 55篇 |
1990年 | 19篇 |
1989年 | 32篇 |
1988年 | 18篇 |
1987年 | 32篇 |
1986年 | 15篇 |
1985年 | 19篇 |
1984年 | 23篇 |
1983年 | 24篇 |
1982年 | 23篇 |
1981年 | 22篇 |
1980年 | 14篇 |
1979年 | 23篇 |
1978年 | 9篇 |
1976年 | 7篇 |
1975年 | 4篇 |
1974年 | 4篇 |
排序方式: 共有5744条查询结果,搜索用时 15 毫秒
1.
2.
《Free radical research》2013,47(1-3):3-10
The role of free radicals and active states of oxygen in human cancer is as yet unresolved. Various lines of evidence provide strong but inferential evidence that free radical reactions can be of crucial importance in certain carcinogenic mechanisms. A central point in considering free radical reactions in carcinogenesis is that human cancer is really a group of highly diverse diseases for which the initial causation and the progression to clinical disease occur through a wide variety of mechanisms. Furthermore, for many human cancers it appears that there are alternate pathways capable of tumor initiation and tumor progression. While for certain of these pathways free radical reactions appear necessary, it is unlikely that there are human cancers for which free radicals, or any other mechanism, are sufficient for the entire processbeginning with the genetic alteration leading to a somatic mutation and eventually resulting in clinically overt disease. It is crucial that we view free radical reactions as aong a panoply of mechanisms leading to human cancer, and consider research about the role of free radicals in cancer as opportunities to prevent the initiation or progression of human cancer. 相似文献
3.
《Cell reports》2020,30(3):725-738.e4
4.
Okadaic acid (OA), a protein phosphatase inhibitor, was found to induce hyperphosphorylation and reorganization of vimentin intermediate filaments in 9L rat brain tumor cells. The process was dose dependent. Vimentin phosphorylation was initially enhanced by 400 nM OA in 30 min and reached maximal level (about 26-fold) when cells were treated with 400 nM OA for 90 min. Upon removal of OA, dephosphorylation of the hyperphosphorylated vimentin was observed and the levels of phosphorylation returned to that of the controls after the cells recovered under normal growing conditions for 11 h. The phosphorylation and dephosphorylation of vimentin induced by OA concomitantly resulted in reversible reorganization of vimentin filaments and alteration of cell morphology. Cells rounded up as they were entering mitosis in the presence of OA and returned to normal appearance after 11 h of recovery. Immuno-staining with anti-vimentin antibody revealed that vimentin filaments were disassembled and clustered around the nucleus when the cells were treated with OA but subsequently returned to the filamentous states when OA was removed. Two-dimensional electrophoresis analysis further revealed that hyperphosphorylation of vimentin generated at least seven isoforms having different isoelectric points. Furthermore, the enhanced vimentin phosphorylation was accompanied by changes in the detergent-solubility of the protein. In untreated cells, the detergent-soluble and -insoluble vimentins were of equal amounts but the solubility could be increased when vimentins were hyperphosphorylated in the presence of OA. Taken together, the results indicated that OA could be involved in reversible hyperphosphorylation and reorganization of vimentin intermediate filaments, which may play an important role in the structure-function regulation of cytoskeleton in the cell. 相似文献
5.
6.
7.
8.
9.
Hongchi Yu Yang Shen Jingsi Jin Yingying Zhang Tang Feng 《Cell Adhesion & Migration》2018,12(1):56-68
Hepatocellular carcinoma (HCC) is a subtype of malignant liver cancer with poor prognosis and limited treatment options. It is noteworthy that mechanical forces in tumor microenvironment play a pivotal role in mediating the behaviors and functions of tumor cells. As an instrumental type of mechanical forces in vivo, fluid shear stress (FSS) has been reported having potent physiologic and pathologic effects on cancer progression. However, the time-dependent mechanochemical transduction in HCC induced by FSS remains unclear. In this study, hepatocellular carcinoma HepG2 cells were exposed to 1.4 dyn/cm2 FSS for transient duration (15s and 30s), short duration (5 min, 15 min and 30 min) and long duration (1h, 2h and 4h), respectively. The expression and translocation of Integrins induced FAK-Rho GTPases signaling events were examined. Our results showed that FSS endowed HepG2 cells with higher migration ability via reorganizing cellular F-actin and disrupting intercellular tight junctions. We further demonstrated that FSS regulated the expression and translocation of Integrins and their downstream signaling cascade in time-dependent patterns. The FSS downregulated focal adhesion components (Paxillin, Vinculin and Talin) while upregulated the expression of Rho GTPases (Cdc42, Rac1 and RhoA) in long durations. These results indicated that FSS enhanced tumor cell migration through Integrins-FAK-Rho GTPases signaling pathway in time-dependent manners. Our in vitro findings shed new light on the role of FSS acting in physiologic and pathological processes during tumor progression, which has emerged as a promising clinical strategy for liver carcinoma. 相似文献
10.
《Biomarkers》2013,18(2):186-191
Context: Usefulness of circulating Chromogranin A (CgA) for the diagnosis of neuroendocrine tumors (NEN) is controversial. The aim of the present study was to assess the actual role of this marker as diagnostic tool. Methods: Serum blood samples were obtained from 42 subjects affected with NEN, 120 subjects affected with non-endocrine neoplasias (non-NEN) and 100 non-neoplastic subjects affected with benign nodular goitre (NNG). Determination of CgA was performed by means of immunoradiometric assay. Results: The CgA levels among NEN-patients were not significantly different from NNG and non-NEN subjects. The Receiver operating characteristic (ROC) curves analysis failed to identify a feasible cut-off value for the differential diagnosis between NEN and the other conditions. Conclusion: Serum CgA is not helpful for the first-line diagnosis of NEN. 相似文献