全文获取类型
收费全文 | 10122篇 |
免费 | 1100篇 |
国内免费 | 1015篇 |
出版年
2024年 | 7篇 |
2023年 | 115篇 |
2022年 | 158篇 |
2021年 | 502篇 |
2020年 | 375篇 |
2019年 | 442篇 |
2018年 | 432篇 |
2017年 | 336篇 |
2016年 | 426篇 |
2015年 | 618篇 |
2014年 | 784篇 |
2013年 | 806篇 |
2012年 | 930篇 |
2011年 | 787篇 |
2010年 | 507篇 |
2009年 | 456篇 |
2008年 | 534篇 |
2007年 | 476篇 |
2006年 | 444篇 |
2005年 | 391篇 |
2004年 | 390篇 |
2003年 | 322篇 |
2002年 | 349篇 |
2001年 | 281篇 |
2000年 | 226篇 |
1999年 | 208篇 |
1998年 | 158篇 |
1997年 | 115篇 |
1996年 | 103篇 |
1995年 | 101篇 |
1994年 | 82篇 |
1993年 | 68篇 |
1992年 | 57篇 |
1991年 | 51篇 |
1990年 | 33篇 |
1989年 | 24篇 |
1988年 | 30篇 |
1987年 | 20篇 |
1986年 | 15篇 |
1985年 | 16篇 |
1984年 | 31篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1965年 | 1篇 |
1955年 | 1篇 |
1951年 | 2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.
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
3.
Shraddha Nayak Md. Abdul H. Khan Tina C. Wan Hong Pei Joel Linden Melinda R. Dwinell Aron M. Geurts John D. Imig John A. Auchampach 《Purinergic signalling》2015,11(4):519-531
The A2B adenosine receptor (AR) has emerged as a unique member of the AR family with contrasting roles during acute and chronic disease states. We utilized zinc-finger nuclease technology to create A2BAR gene (Adora2b)-disrupted rats on the Dahl salt-sensitive (SS) genetic background. This strategy yielded a rat strain (SS-Adora2b mutant rats) with a 162-base pair in-frame deletion of Adora2b that included the start codon. Disruption of A2BAR function in SS-Adora2b mutant rats was confirmed by loss of agonist (BAY 60-6583 or NECA)-induced cAMP accumulation and loss of interleukin-6 release from isolated fibroblasts. In addition, BAY 60-6583 produced a dose-dependent increase in glucose mobilization that was absent in SS-Adora2b mutants. Upon initial characterization, SS-Adora2b mutant rats were found to exhibit increased body weight, a transient delay in glucose clearance, and reduced proinflammatory cytokine production following challenge with lipopolysaccharide (LPS). In addition, blood pressure was elevated to a greater extent (∼15–20 mmHg) in SS-Adora2b mutants as they aged from 7 to 21 weeks. In contrast, hypertension augmented by Ang II infusion was attenuated in SS-Adora2b mutant rats. Despite differences in blood pressure, indices of renal and cardiac injury were similar in SS-Adora2b mutants during Ang II-augmented hypertension. We have successfully created and validated a new animal model that will be valuable for investigating the biology of the A2BAR. Our data indicate varying roles for A2BAR signaling in regulating blood pressure in SS rats, playing both anti- and prohypertensive roles depending on the pathogenic mechanisms that contribute to blood pressure elevation. 相似文献
4.
5.
6.
Household‐level correlates of children's physical activity levels in and across 12 countries 下载免费PDF全文
Deirdre M. Harrington Fiona Gillison Stephanie T. Broyles Jean‐Philippe Chaput Mikael Fogelholm Gang Hu Rebecca Kuriyan Anura Kurpad Allana G. LeBlanc Carol Maher Jose Maia Victor Matsudo Timothy Olds Vincent Onywera Olga L. Sarmiento Martyn Standage Mark S. Tremblay Catrine Tudor‐Locke Pei Zhao Peter T. Katzmarzyk for the ISCOLE Research Group 《Obesity (Silver Spring, Md.)》2016,24(10):2150-2157
7.
Chong Gang-Gang Huang Xiao-Jun Di Jun-Hua Xu Dao-Zhu He Yu-Cai Pei Ya-Nan Tang Ya-Jie Ma Cui-Luan 《Bioprocess and biosystems engineering》2018,41(4):501-510
Bioprocess and Biosystems Engineering - Based on the Prussian blue spectrophotometric method, one high-throughput screening strategy for screening lignin-degrading microorganisms was built on... 相似文献
8.
9.
Xiaoyan Chen Dafang Zhong Haiyan Xu Barbara Schug Henning Blume 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2001,755(1-2)
A rapid, selective and sensitive HPLC–tandem mass spectrometry method was developed and validated for simultaneous determination of flupirtine and its active metabolite D-13223 in human plasma. The analytes and internal standard diphenhydramine were extracted from plasma samples by liquid–liquid extraction, and chromatographed on a C18 column. The mobile phase consisted of acetonitrile–water–formic acid (60:40:1, v/v/v), at a flow rate of 0.5 ml/min. Detection was performed on a triple quadrupole tandem mass spectrometer by selected reaction monitoring (SRM) mode via atmospheric pressure chemical ionization (APCI). The method has a limit of quantitation of 10 ng/ml for flupirtine and 2 ng/ml for D-13223, using 0.5-ml plasma sample. The linear calibration curves were obtained in the concentration range of 10.0–1500.0 ng/ml for flupirtine and 2.0–300.0 ng/ml for D-13223. The intra- and inter-run precision (RSD), calculated from quality control (QC) samples was less than 7.2% for flupirtine and D-13223. The accuracy as determined from QC samples was less than 5% for the analytes. The overall extraction recoveries of flupirtine and D-13223 were determined to be about 66% and 78% on average, respectively. The method was applied for the evaluation of the pharmacokinetics of flupirtine and active metabolite D-13223 in volunteers following peroral administration. 相似文献
10.
Z Zhong A Toukdarian D Helinski V Knauf S Sykes J E Wilkinson C O'Bryne T Shea C DeLoughery R Caspi 《Applied and environmental microbiology》2001,67(12):5771-5779
An agar-degrading marine bacterium identified as a Microscilla species was isolated from coastal California marine sediment. This organism harbored a single 101-kb circular DNA plasmid designated pSD15. The complete nucleotide sequence of pSD15 was obtained, and sequence analysis indicated a number of genes putatively encoding a variety of enzymes involved in polysaccharide utilization. The most striking feature was the occurrence of five putative agarase genes. Loss of the plasmid, which occurred at a surprisingly high frequency, was associated with loss of agarase activity, supporting the sequence analysis results. 相似文献