全文获取类型
收费全文 | 21878篇 |
免费 | 2193篇 |
国内免费 | 2162篇 |
出版年
2024年 | 12篇 |
2023年 | 257篇 |
2022年 | 354篇 |
2021年 | 1095篇 |
2020年 | 883篇 |
2019年 | 997篇 |
2018年 | 975篇 |
2017年 | 745篇 |
2016年 | 942篇 |
2015年 | 1402篇 |
2014年 | 1643篇 |
2013年 | 1816篇 |
2012年 | 2127篇 |
2011年 | 1783篇 |
2010年 | 1099篇 |
2009年 | 1046篇 |
2008年 | 1180篇 |
2007年 | 1011篇 |
2006年 | 906篇 |
2005年 | 806篇 |
2004年 | 653篇 |
2003年 | 612篇 |
2002年 | 598篇 |
2001年 | 430篇 |
2000年 | 364篇 |
1999年 | 372篇 |
1998年 | 244篇 |
1997年 | 228篇 |
1996年 | 211篇 |
1995年 | 192篇 |
1994年 | 178篇 |
1993年 | 137篇 |
1992年 | 145篇 |
1991年 | 111篇 |
1990年 | 103篇 |
1989年 | 79篇 |
1988年 | 84篇 |
1987年 | 62篇 |
1986年 | 61篇 |
1985年 | 62篇 |
1984年 | 62篇 |
1983年 | 28篇 |
1982年 | 28篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 16篇 |
1978年 | 6篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Honghong Yang Yuanyuan Zhang Zhihai Wang Shixun Zhong Guohua Hu Wenqi Zuo 《Bioelectromagnetics》2020,41(3):219-229
To investigate the possible mechanisms for biological effects of 1,800 MHz mobile radiofrequency radiation (RFR), the radiation-specific absorption rate was applied at 2 and 4 W/kg, and the exposure mode was 5 min on and 10 min off (conversation mode). Exposure time was 24 h short-term exposure. Following exposure, to detect cell DNA damage, cell apoptosis, and reactive oxygen species (ROS) generation, the Comet assay test, flow cytometry, DAPI (4′,6-diamidino-2-phenylindole dihydrochloride) staining, and a fluorescent probe were used, respectively. Our experiments revealed that mobile phone RFR did not cause DNA damage in marginal cells, and the rate of cell apoptosis did not increase (P > 0.05). However, the production of ROS in the 4 W/kg exposure group was greater than that in the control group (P < 0.05). In conclusion, these results suggest that mobile phone energy was insufficient to cause cell DNA damage and cell apoptosis following short-term exposure, but the cumulative effect of mobile phone radiation still requires further confirmation. Activation of the ROS system plays a significant role in the biological effects of RFR. Bioelectromagnetics. © 2020 The Authors. Bioelectromagnetics published by Wiley Periodicals, Inc. 相似文献
2.
3.
4.
Xun Qi Yonghui Yuan Ke Xu Hongshan Zhong Zhen Zhang Huan Zhai Gefei Guan Guibo Yu 《PloS one》2015,10(5)
BackgroundPeripheral artery disease (PAD), which is caused by atherosclerosis, results in progressive narrowing and occlusion of the peripheral arteries and inhibits blood flow to the lower extremities. Therapeutic angiogenesis is a promising strategy for treating ischemia caused by PAD. Nitric oxide (NO) has been shown to be a key mediator of angiogenesis. It has been demonstrated that β-cyclodextrincan stimulate vessel growth in rabbit corneas. In this study, we assessed the mechanism of action and therapeutic potential of a new angiogenic molecule, (2-hydroxypropyl)-β-cyclodextrin (2HP-β-CD).ConclusionsTherapeutic angiogenesis by 2HP-β-CD may be beneficial to patients with PAD. 相似文献
5.
6.
7.
Fluid-structural coupling occurs when microcantilever sensors vibrate in a fluid. Due to the complexity of the mechanical characteristics of microcantilevers and lack of high-precision microscopic mechanical testing instruments, effective methods for studying the fluid-structural coupling of microcantilevers are lacking, especially for non-rectangular microcantilevers. Here, we report fluid-structure interactions (FSI) of the cable-membrane structure via a macroscopic study. The simplified aeroelastic model was introduced into the microscopic field to establish a fluid-structure coupling vibration model for microcantilever sensors. We used the finite element method to solve the coupled FSI system. Based on the simplified aeroelastic model, simulation analysis of the effects of the air environment on the vibration of the commonly used rectangular microcantilever was also performed. The obtained results are consistent with the literature. The proposed model can also be applied to the auxiliary design of rectangular and non-rectangular sensors used in fluid environments. 相似文献
8.
9.
10.