全文获取类型
收费全文 | 39143篇 |
免费 | 2997篇 |
国内免费 | 2916篇 |
专业分类
45056篇 |
出版年
2024年 | 98篇 |
2023年 | 524篇 |
2022年 | 1190篇 |
2021年 | 2178篇 |
2020年 | 1372篇 |
2019年 | 1728篇 |
2018年 | 1737篇 |
2017年 | 1180篇 |
2016年 | 1650篇 |
2015年 | 2408篇 |
2014年 | 2840篇 |
2013年 | 3086篇 |
2012年 | 3587篇 |
2011年 | 3174篇 |
2010年 | 1995篇 |
2009年 | 1615篇 |
2008年 | 1969篇 |
2007年 | 1721篇 |
2006年 | 1590篇 |
2005年 | 1287篇 |
2004年 | 1058篇 |
2003年 | 914篇 |
2002年 | 761篇 |
2001年 | 665篇 |
2000年 | 588篇 |
1999年 | 628篇 |
1998年 | 351篇 |
1997年 | 364篇 |
1996年 | 347篇 |
1995年 | 316篇 |
1994年 | 332篇 |
1993年 | 263篇 |
1992年 | 312篇 |
1991年 | 242篇 |
1990年 | 213篇 |
1989年 | 189篇 |
1988年 | 127篇 |
1987年 | 101篇 |
1986年 | 93篇 |
1985年 | 86篇 |
1984年 | 59篇 |
1983年 | 53篇 |
1982年 | 34篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 11篇 |
1976年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Yan Du Mei‐ju Zhang Lan‐lan Li Xiao‐Lin Xu Hao Chen Yu‐bin Feng Yan Li Xiao‐qin Peng Fei‐hu Chen 《Journal of cellular and molecular medicine》2020,24(12):6952-6965
Acute myeloid leukaemia (AML) remains a therapeutic challenge and improvements in chemotherapy are needed. 4‐Amino‐2‐trifluoromethyl‐phenyl retinate (ATPR), a novel all‐trans retinoic acid (ATRA) derivative designed and synthesized by our team, has been proven to show superior anticancer effect compared with ATRA on various cancers. However, its potential effect on AML remains largely unknown. Lactate dehydrogenase B (LDHB) is the key glycolytic enzyme that catalyses the interconversion between pyruvate and lactate. Currently, little is known about the role of LDHB in AML. In this study, we found that ATPR showed antileukaemic effects with RARα dependent in AML cells. LDHB was aberrantly overexpressed in human AML peripheral blood mononuclear cell (PBMC) and AML cell lines. A lentiviral vector expressing LDHB‐targeting shRNA was constructed to generate a stable AML cells with low expression of LDHB. The effect of LDHB knockdown on differentiation and cycle arrest of AML cells was assessed in vitro and vivo, including involvement of Raf/MEK/ERK signalling. Finally, these data suggested that ATPR showed antileukaemic effects by RARα/LDHB/ ERK‐glycolysis signalling axis. Further studies should focus on the underlying leukaemia‐promoting mechanisms and investigate LDHB as a therapeutic target. 相似文献
992.
993.
Yan Xu Chun Tang Shengyu Tan Juan Duan Hongmei Tian Yu Yang 《Journal of cellular and molecular medicine》2020,24(11):6253-6262
In this study, we investigated the effects of isorhamnetin on myocardial ischaemia reperfusion (I/R) injury in Langendorff-perfused rat hearts. Isorhamnetin treatment (5, 10 and 20 μg/mL) significantly alleviated cardiac morphological injury, reduced myocardial infarct size, decreased the levels of marker enzymes (LDH and CK) and improved the haemodynamic parameters, reflected by the elevated levels of the left ventricular developed pressure (LVDP), coronary flow (CF) and the maximum up/down velocity of left ventricular pressure (+dp/dtmax). Moreover, isorhamnetin reperfusion inhibited apoptosis of cardiomyocytes in the rats subjected to cardiac I/R in a dose-dependent manner concomitant with decreased protein expression of Bax and cleaved-caspase-3, as well as increased protein expression of Bcl-2. In addition, I/R-induced oxidative stress was manifestly mitigated by isorhamnetin treatment, as showed by the decreased malondialdehyde (MDA) level and increased antioxidant enzymes activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). These results indicated that isorhamnetin exerts a protective effect against I/R-induced myocardial injury through the attenuation of apoptosis and oxidative stress. 相似文献
994.
Yunjie Lu Yunfei Duan Qinghua Xu Li Zhang Weibo Chen Zhen Qu Baoqiang Wu Wensong Liu Longqing Shi Di Wu Yan Yang Donglin Sun Xuemin Chen 《Journal of cellular and molecular medicine》2020,24(2):1311-1318
Although the diagnosis and therapy approach developed, techniques for the early diagnosis of HCC remain insufficient which results in poor prognosis of patients. The traditional biomarker AFP, however, has been proved with low specificity. Circulating exosomal ncRNAs revealed different profiles reflecting the characteristics of tumour. In this study, we mainly focused on circulating exosomal ncRNAs which might be the fingerprint for HCC, especially for the diagnosis or metastasis prediction. A high throughput lncRNA microarray in exosomes extracted from cell‐free plasma was applied. The risk score analysis was employed to screen the potential exosome‐derived lncRNAs in two independent sets based on different clinical parameters in 200 paired HCC patients. After a multi‐stage validation, we finally revealed three lncRNAs, ENSG00000248932.1, ENST00000440688.1 and ENST00000457302.2, increased in HCC comparing with the both chronic hepatitis (CH) patients and cancer‐free controls. ROC curve revealed a higher sensitivity and specificity in predicting the occurrence of HCC from cancer‐free controls and CH patients with the area under curve (AUC) of 0.905 and 0.879 by combining AFP. The three lncRNA panel combined with AFP also indicted a fingerprint function in predicting the metastasis of HCC with the AUC of 0.870. In conclusion, ENSG00000248932.1, ENST00000440688.1 and ENST00000457302.2 might be the potential biomarker for the tumorigenesis prediction from CH patients or healthy controls and may also be applied for dynamic monitoring the metastasis of HCC. 相似文献
995.
Lei Zhu Ming Zhang Guanqing Zhou Tianyu Hao Jinqiu Xu Jing Wang Chaoqun Qiu Nathaniel Prine Jazib Ali Wei Feng Xiaodan Gu Zaifei Ma Zheng Tang Haiming Zhu Lei Ying Yongming Zhang Feng Liu 《Liver Transplantation》2020,10(18)
Single‐layered organic solar cells (OSCs) using nonfullerene acceptors have reached 16% efficiency. Such a breakthrough has inspired new sparks for the development of the next generation of OSC materials. In addition to the optimization of electronic structure, it is important to investigate the essential solid‐state structure that guides the high efficiency of bulk heterojunction blends, which provides insight in understanding how to pair an efficient donor–acceptor mixture and refine film morphology. In this study, a thorough analysis is executed to reveal morphology details, and the results demonstrate that Y6 can form a unique 2D packing with a polymer‐like conjugated backbone oriented normal to the substrate, controlled by the processing solvent and thermal annealing conditions. Such morphology provides improved carrier transport and ultrafast hole and electron transfer, leading to improved device performance, and the best optimized device shows a power conversion efficiency of 16.88% (16.4% certified). This work reveals the importance of film morphology and the mechanism by which it affects device performance. A full set of analytical methods and processing conditions are executed to achieve high efficiency solar cells from materials design to device optimization, which will be useful in future OSC technology development. 相似文献
996.
Yawei Chen Jianming Li Zhanwu Lei Yakun Huo Lanlan Yang Suyuan Zeng Honghe Ding Yi Qin Yulin Jie Fanyang Huang Qi Li Junfa Zhu Ruiguo Cao Genqiang Zhang Shuhong Jiao Dongsheng Xu 《Liver Transplantation》2020,10(7)
Transition metal sulfides hold promising potentials as Li‐free conversion‐type cathode materials for high energy density lithium metal batteries. However, the practical deployment of these materials is hampered by their poor rate capability and short cycling life. In this work, the authors take the advantage of hollow structure of CuS nanoboxes to accommodate the volume expansion and facilitate the ion diffusion during discharge–charge processes. As a result, the hollow CuS nanoboxes achieve excellent rate performance (≈371 mAh g?1 at 20 C) and ultra‐long cycle life (>1000 cycles). The structure and valence evolution of the CuS nanobox cathode are identified by scanning electron microscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy. Furthermore, the lithium storage mechanism is revealed by galvanostatic intermittent titration technique and operando Raman spectroscopy for the initial charge–discharge process and the following reversible processes. These results suggest that the hollow CuS nanobox material is a promising candidate as a low‐cost Li‐free cathode material for high‐rate and long‐life lithium metal batteries. 相似文献
997.
Dong Cai Bingke Liu Dehua Zhu Duo Chen Mengjie Lu Junming Cao Yanhu Wang Wenhao Huang Yong Shao Haoran Tu Wei Han 《Liver Transplantation》2020,10(19)
Lithium–sulfur batteries are a promising high energy output solution for substitution of traditional lithium ion batteries. In recent times research in this field has stepped into the exploration of practical applications. However, their applications are impeded by cycling stability and short life‐span mainly due to the notorious polysulfide shuttle effect. In this work, a multifunctional sulfur host fabricated by grafting highly conductive Co3Se4 nanoparticles onto the surface of an N‐doped 3D carbon matrix to inhibit the polysulfide shuttle and improve the sulfur utilization is proposed. By regulating the carbon matrix and the Co3Se4 distribution, N‐CN‐750@Co3Se4‐0.1 m with abundant polar sites is experimentally and theoretically shown to be a good LiPSs absorbent and a sulfur conversion accelerator. The S/N‐CN‐750@Co3Se4‐0.1 m cathode shows excellent sulfur utilization, rate performance, and cyclic durability. A prolonged cycling test of the as‐fabricated S/N‐CN‐750@Co3Se4‐0.1 m cathode is carried out at 0.2 C for more than 5 months which delivers a high initial capacity of 1150.3 mAh g?1 and retains 531.0 mAh g?1 after 800 cycles with an ultralow capacity reduction of 0.067% per cycle, maintaining Coulombic efficiency of more than 99.3%. The reaction details are characterized and analyzed by ex situ measurements. This work highly emphasizes the potential capabilities of transition‐metal selenides in lithium–sulfur batteries. 相似文献
998.
Shuming Dou Jie Xu Xiaoya Cui Weidi Liu Zhicheng Zhang Yida Deng Wenbin Hu Yanan Chen 《Liver Transplantation》2020,10(33)
Functional nanomaterials are playing a crucial role in the emerging field of energy‐related devices. Recently, as a novel synthesis method, high‐temperature shock (HTS), which is rapid, low cost, eco‐friendly, universal, scalable, and controllable, has provided a promising option for the rational design and synthesis of various high‐quality nanomaterials. In this report, the HTS technique, including the equipment setup and operating principle, is systematically introduced, and recent progress in the synthesis of nanomaterials for energy storage and conversion applications using this HTS method is summarized. The growth mechanisms of nanoparticles and carbonaceous nanomaterials are thoroughly discussed, followed by the summary of the characteristic advantages of the HTS strategy. A series of nanomaterials prepared by the HTS method, including carbon‐based films, metal nanoparticles and compound nanoparticles, show high performance in the diverse applications of storage energy batteries, highly active catalysts, and smart energy devices. Finally, the future perspectives and directions of HTS in nanomanufacturing for broader applications are presented. 相似文献
999.
Xu Luo Pengxia Ji Pengyan Wang Ruilin Cheng Ding Chen Can Lin Jianan Zhang Jianwei He Zuhao Shi Neng Li Shengqiang Xiao Shichun Mu 《Liver Transplantation》2020,10(17)
Rational design and construction of bifunctional electrocatalysts with excellent activity and durability is imperative for water splitting. Herein, a novel top‐down strategy to realize a hierarchical branched Mo‐doped sulfide/phosphide heterostructure (Mo‐Ni3S2/NixPy hollow nanorods), by partially phosphating Mo‐Ni3S2/NF flower clusters, is proposed. Benefitting from the optimized electronic structure configuration, hierarchical branched hollow nanorod structure, and abundant heterogeneous interfaces, the as‐obtained multisite Mo‐Ni3S2/NixPy/NF electrode has remarkable stability and bifunctional electrocatalytic activity in the hydrogen evolution reaction (HER)/oxygen evolution reaction (OER) in 1 m KOH solutions. It possesses an extremely low overpotential of 238 mV at the current density of 50 mA cm?2 for OER. Importantly, when assembled as anode and cathode simultaneously, it merely requires an ultralow cell voltage of 1.46 V to achieve the current density of 10 mA cm?2, with excellent durability for over 72 h, outperforming most of the reported Ni‐based bifunctional materials. Density functional theory results further confirm that the doped heterostructure can synergistically optimize Gibbs free energies of H and O‐containing intermediates (OH*, O*, and OOH*) during HER and OER processes, thus accelerating the catalytic kinetics of electrochemical water splitting. This work demonstrates the importance of the rational combination of metal doping and interface engineering for advanced catalytic materials. 相似文献
1000.
The unique physicochemical properties of (2D) nanomaterials make them well‐suited for use in sustainable energy applications. Many of these materials can be further improved with vacancy engineering. This review details recent progress in the vacancy engineering of ultrathin 2D nanomaterials. For clarity, it mainly focuses on various ultrathin 2D materials in three categories: Xa&XaYb‐, MaXb‐, or MaXbYc‐structured materials. Recently developed vacancies in different types of ultrathin 2D materials, as well as their preparation and characterization, are described. Emphasis is placed on the potential electrochemical energy storage and conversion applications of these materials. This review considers the relationship between vacancy properties and material categories of various ultrathin 2D materials in terms of application requirements, preparation, and characterization techniques. The challenges and future outlook of this promising field are summarized. 相似文献