全文获取类型
收费全文 | 21281篇 |
免费 | 1918篇 |
国内免费 | 1645篇 |
出版年
2023年 | 161篇 |
2022年 | 195篇 |
2021年 | 632篇 |
2020年 | 505篇 |
2019年 | 676篇 |
2018年 | 709篇 |
2017年 | 571篇 |
2016年 | 880篇 |
2015年 | 1215篇 |
2014年 | 1475篇 |
2013年 | 1545篇 |
2012年 | 1823篇 |
2011年 | 1776篇 |
2010年 | 1179篇 |
2009年 | 1036篇 |
2008年 | 1283篇 |
2007年 | 1197篇 |
2006年 | 1074篇 |
2005年 | 1041篇 |
2004年 | 967篇 |
2003年 | 889篇 |
2002年 | 788篇 |
2001年 | 546篇 |
2000年 | 433篇 |
1999年 | 381篇 |
1998年 | 225篇 |
1997年 | 196篇 |
1996年 | 134篇 |
1995年 | 118篇 |
1994年 | 85篇 |
1993年 | 63篇 |
1992年 | 112篇 |
1991年 | 113篇 |
1990年 | 71篇 |
1989年 | 76篇 |
1988年 | 67篇 |
1987年 | 56篇 |
1986年 | 38篇 |
1985年 | 44篇 |
1984年 | 42篇 |
1983年 | 25篇 |
1982年 | 29篇 |
1981年 | 24篇 |
1979年 | 30篇 |
1978年 | 27篇 |
1977年 | 26篇 |
1976年 | 27篇 |
1974年 | 26篇 |
1971年 | 26篇 |
1970年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Yu Si-in Kim Hyojin Yun Dae-Jin Suh Mi Chung Lee Byeong-ha 《Plant molecular biology》2019,99(1-2):135-148
Plant Molecular Biology - A Kelch repeat F-box containing protein, SMALL AND GLOSSY LEAVES1 (SAGL1) regulates phenylpropanoid biosynthesis as a post-translational regulator for PAL1 (phenylalanine... 相似文献
992.
Plant Molecular Biology - Plant defensin AtPDF2.6 is not secreted to the apoplast and localized in cytoplasm. AtPDF2.6 is mainly expressed in root vascular bundles of xylem parenchyma cell, and... 相似文献
993.
Young Seung Lee Jae‐Young Chung Sang Bong Jeon Ae‐Kyoung Lee Hyung‐Do Choi 《Bioelectromagnetics》2019,40(7):445-457
This paper proposes a novel in vitro exposure system operating at millimeter‐wave (mmWave) 28 GHz, one of the frequency bands under consideration for fifth generation (5G) communication. We employed the field uniformity concept along cross‐sectional observation planes at shorter distances from the radiation antenna for better efficiency and a small‐size system. A choke‐ring antenna was designed for this purpose in consideration of a wider beamwidth (BW) and a symmetric far‐field pattern across three principal planes. The permittivity of Dulbecco's modified Eagle's medium solution was measured to examine the specific absorption rate (SAR) of the skin cell layer inside a Petri dish model for a three‐dimensional (3D) cell culture in vitro experiment. The best deployment of Petri dishes, taking into account a geometrical field symmetry, was proposed. Local SAR values within the cell layer among the Petri dishes were determined with different polarization angles. It was determined that this polarization effect should be considered when the actual exposure and deployment were conducted. We finally proposed an in vitro exposure system based on the field uniformity including downward exposure from an antenna for 3D cell culture experiments. A small‐size chamber system was obtained, and the size was estimated using the planar near‐field chamber design rule. Bioelectromagnetics. 2019;40:445–457. © 2019 Bioelectromagnetics Society 相似文献
994.
Chung Hyung-Joo Kim Muwoong Jung Junyang Jeong Na Young 《Neurochemical research》2019,44(8):1964-1976
Neurochemical Research - Schwann cells are essential glial cells in the peripheral nervous system (PNS), and dysfunction of Schwann cells can induce various peripheral neurodegenerative diseases.... 相似文献
995.
Jason E. Chung Hannah R. Joo Jiang Lan Fan Daniel F. Liu Alex H. Barnett Supin Chen Charlotte Geaghan-Breiner Mattias P. Karlsson Magnus Karlsson Kye Y. Lee Hexin Liang Jeremy F. Magland Jeanine A. Pebbles Angela C. Tooker Leslie F. Greengard Vanessa M. Tolosa Loren M. Frank 《Neuron》2019,101(1):21-31.e5
996.
Jun Yang Xuli Meng Yong Yu Lei Pan Qinghui Zheng 《Bioscience, biotechnology, and biochemistry》2019,83(6):1117-1123
It has been reported that lncRNA POU3F3 was upregulated in esophageal squamous-cell carcinomas, indicating its role as an oncogene in this disease. However, the mechanism of its function and its involvement in other malignancies is unknown. In the present study we found that expression levels of lncRNA POU3F3 were higher in tumor tissues than in adjacent healthy tissues of triple negative breast cancer (TNBC) patients and were significantly and inversely correlated with levels of cleaved caspase 9 only in tumor tissues. In addition, plasma levels of lncRNA POU3F3 were higher in TNBC patients than in healthy controls and were significantly and inversely correlated with levels of cleaved caspase 9 only in TNBC patients. In addition, treatment of exogenous Cleaved Caspase-9 significantly attenuated the effects of lncRNA POU3F3 overexpression on cancer cell proliferation and apoptosis. lncRNA POU3F3 may promote proliferation and inhibit apoptosis of cancer cells in triple-negative breast cancer. 相似文献
997.
The wave wash hunting employed by Orcinus orca, also known as killer whales, is unique in that the prey is hunted outside of the water by generating waves. To quantitatively analyze the specific mechanism of the wave wash, data were obtained using computational fluid dynamics (CFD), and wave theory was introduced as the theoretical background to clarify the mechanism. The relationships between the swimming characteristics and wave parameters are defined in this paper. The results obtained by numerical investigation revealed that the wavelength increased with the swimming speed. Additionally, the wave height increased as the swimming speed increased and the swimming depth became shallower, and subsequently converged to a maximum of 2.42 m. The success of hunting is determined by two wave parameters, which indicate the intensity of the wave wash: the wave height and force exerted on the prey. The metabolic rate and the drag force are considered to evaluate the efficiency of the locomotion, which varied according to the swimming speed (V) and swimming depth (d) of the whales. To generate hunting waves efficiently, the optimal ranges of V and d were estimated to be 3 ~ 5 m/s and 0.5 m ~ 1.1 m respectively. 相似文献
998.
999.
Han Wu Hai Yan Liu Wen Jie Liu Yong Li Shi Dawei Bao 《Journal of cellular biochemistry》2019,120(5):8120-8128
Lung carcinoma is the most common type of malignant tumors globally, and its molecular mechanisms remained unclear. With the aim to investigate the effects of microRNA (miR)-377-5p on the cell development, invasion, metastasis, and cycle of lung carcinoma, this study was performed. We evaluated miR-377-5p expression levels in lung cancer tissues and cell models. Cell viability, proliferation, migration, invasion abilities, and cell cycle distribution were measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, crystal violet, transwell, and flow cytometry assay. Furthermore, expression levels of protein kinase B α subunit (AKT1) and proteins related to cell cycle and epithelial-mesenchymal transition (EMT) were assessed using Western blot analysis and quantitative real-time polymerase chain reaction. These results suggested that miR-377-5p was downregulated in vivo and in cell models, and miR-377-5p overexpression inhibited cell viability, proliferation, migration, invasion, and induced cell-cycle arrest. In addition, as a target of miR-377-5p, AKT1 alleviated the decreases of cell viability, proliferation, migration, invasion, the S-phase cells, the expression of cyclin D1, fibronectin, and vimentin, as well as the increases of the G0/G1-phase cells, the expression of Foxo1, p27 kip1, p21 Cip1 and E-cadherin when miR-377-5p overexpressed. In conclusion, miR-377-5p inhibited cell development and regulated cell cycle distribution and EMT by targeting AKT1, which provided a theoretical basis for further study of lung carcinoma therapeutics. 相似文献
1000.
Qi Wang Quanwei Zhang Yong Zhang Xingxu Zhao 《Journal of cellular biochemistry》2019,120(4):6729-6740
Oxoglutarate receptor 1 (OXGR1), as one of the intermediates in G protein-coupled receptors (GPCRs), plays a crucial role in the citric acid cycle receptor of α-ketoglutarate and metabolism. GPCR can control the cell proliferation by regulating the downstream signaling of G protein signaling pathways. The PI3K/AKT pathway transmits the downstream signals of GPCRs and receptor tyrosine kinases. However, the specific role of OXGR1 promoting cell proliferation and differentiation are still unknown. In current study, the over-expression vector and knockdown sequence of yak OXGR1 were transfected into yak fibroblasts, and the effects were detected by a series of assays. The results revealed that OXGR1 expression in yak lung parenchyma tissue was significantly higher than that of other tissues. In yak fibroblasts, the upregulated expression of OXGR1 resulted in activating the PIK3CG (downstream signal) of the PI3K/AKT1 pathway that can upregulated the expression of proliferation genes ( CDK1, PCNA, and CyclinD1) and promote cell proliferation. Conversely, the downregulated expression of OXGR1 inhibited cell proliferation via PI3K/AKT1 pathway. Cell cycle and cell proliferation assays demonstrated that over-expression of OXGR1 can enhanced the DNA synthesis and promoted yak fibroblasts proliferation. While the conversely, knockdown of OXGR1 can decreased DNA synthesis and inhibited cell proliferation. These results illustrated that changes of OXGR1 expression can trigger the fibroblasts proliferation via PI3K/AKT signaling pathway, which indicating that OXGR1 is a novel regulator for cell proliferation and differentiation. Furthermore, these results provide evidence supporting the functional role of GPCRs-PI3K-AKT1 and OXGR1 in cell proliferation. 相似文献