全文获取类型
收费全文 | 54675篇 |
免费 | 8442篇 |
国内免费 | 6292篇 |
专业分类
化学 | 28534篇 |
晶体学 | 574篇 |
力学 | 2672篇 |
综合类 | 338篇 |
数学 | 4674篇 |
物理学 | 16865篇 |
无线电 | 15752篇 |
出版年
2024年 | 268篇 |
2023年 | 1322篇 |
2022年 | 1671篇 |
2021年 | 2110篇 |
2020年 | 2124篇 |
2019年 | 1923篇 |
2018年 | 1709篇 |
2017年 | 1715篇 |
2016年 | 2348篇 |
2015年 | 2590篇 |
2014年 | 3075篇 |
2013年 | 3682篇 |
2012年 | 4486篇 |
2011年 | 4550篇 |
2010年 | 3243篇 |
2009年 | 3427篇 |
2008年 | 3626篇 |
2007年 | 3216篇 |
2006年 | 3123篇 |
2005年 | 2492篇 |
2004年 | 1895篇 |
2003年 | 1646篇 |
2002年 | 1549篇 |
2001年 | 1299篇 |
2000年 | 1293篇 |
1999年 | 1187篇 |
1998年 | 1054篇 |
1997年 | 951篇 |
1996年 | 947篇 |
1995年 | 838篇 |
1994年 | 716篇 |
1993年 | 561篇 |
1992年 | 573篇 |
1991年 | 432篇 |
1990年 | 355篇 |
1989年 | 281篇 |
1988年 | 240篇 |
1987年 | 190篇 |
1986年 | 182篇 |
1985年 | 170篇 |
1984年 | 114篇 |
1983年 | 74篇 |
1982年 | 69篇 |
1981年 | 42篇 |
1980年 | 17篇 |
1979年 | 10篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1957年 | 4篇 |
1911年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
122.
可见光主动成像系统被广泛应用于成像侦察领域,激光压制干扰是一种可以利用的反制手段。合理地对激光干扰效果进行评估,对于干扰一方具有重要意义。为了更客观地评价激光干扰对成像侦察的影响,从可见光成像侦察的特点出发,对激光干扰可见光成像效果进行划分,确定了干扰效果评估需求。建立了可见光图像的激光干扰效果评估模型,结合基于YOLOv4的目标检测置信度及WFSIM算法的三个图像特征表征指标,形成了对应的评估体系。构建了一套参数可调的激光干扰图像采集及评估分析实验系统,对人体目标进行图像采集,验证了提出的评估体系及方法。 相似文献
123.
Ting Wu Tianqun Lang Chao Zheng Wenlu Yan Yu Li Runqi Zhu Xin Huang Huae Xu Yaping Li Qi Yin 《Advanced functional materials》2023,33(7):2212109
The red blood cell membrane (RBCm) provides tight protection, lowers the immunogenicity, and prolongs the circulation time of drugs in vivo when acting as the coating of drug delivery systems. However, the cellular uptake and release of drugs are hindered by RBCm. Docetaxel (DTX) is the first-line medicine for treating triple-negative breast cancer (TNBC), but it induces tumor metastasis. To solve these dilemmas, in this study, the photosensitizer 1,1-dioctadecyl-3,3,3,3-tetramethylindotricarbocyanine iodide (DiR)-modified RBCm (DM) is prepared, which is coated onto a hybrid micelle consisting of the prodrugs of DTX and the anti-metastasis agent calcitriol (CTL), obtaining a nanoparticle, named HDC-DM. In a 4T1 tumor-bearing mouse model, after injecting HDC-DM, the intratumoral DTX and CTL concentrations are increased by 1.7 and 2.5 times compared with the free drug groups. After irradiating tumors with near-infrared laser, DiR elicits the photothermal effect, triggering the rupture of RBCm and drug release, promoting drug penetration in tumors, and inducing immunogenic cell death. The tumor growth inhibition rate is 77%, and the formation of lung metastases is reduced by 82%, with good biocompatibility. It is suggested that the combination of phototherapy, chemotherapy, and anti-metastatic therapy using HDC-DM is expected to be a powerful strategy for treating TNBC. 相似文献
124.
Jiacheng Yin Na Li Ming Liu Zhigang Li Xuemin Wang Mingren Cheng Ming Zhong Wei Li Yunhua Xu Xian-He Bu 《Advanced functional materials》2023,33(21):2211950
Organic redox-active materials are promising electrode candidates for lithium-ion batteries by virtue of their designable structure and cost-effectiveness. However, their poor electrical conductivity and high solubility in organic electrolytes limit the device's performance and practical applications. Herein, the π-conjugated nitrogen-containing heteroaromatic molecule hexaazatriphenylene (HATN) is strategically embedded with redox-active centers in the skeleton of a Cu-based 2D conductive metal–organic framework (2D c-MOF) to optimize the lithium (Li) storage performance of organic electrodes, which delivers improved specific capacity (763 mAh g−1 at 300 mA g−1), long-term cycling stability (≈90% capacity retention after 600 cycles at 300 mA g−1), and excellent rate performance. The correlation of experimental and computational results confirms that this high Li storage performance derives from the maximum number of active sites (CN sites in the HATN unit and CO sites in the CuO4 unit), favorable electrical conductivity, and efficient mass transfer channels. This strategy of integrating multiple redox-active moieties into the 2D c-MOF opens up a new avenue for the design of high-performance electrode materials. 相似文献
125.
Xu Cai Yu Xiao Bingwen Zhang Yanhui Yang Jun Wang Huamin Chen Guozhen Shen 《Advanced functional materials》2023,33(43):2304456
MXene materials emerge as promising candidates for energy harvesting and storage application. In this study, the effect of the surface chemistry on the work function of MXenes, which determines the performance of MXene-based triboelectric nanogenerator (TENG), is elucidated. First-principles calculations reveal that the surface functional group greatly influences MXene work function: OH termination reduces the work function with respect to that of bare surface, while F and Cl increase it. Then, work functions are experimentally determined by Kelvin probe force microscopy. The MXene prepared by gentle etching at 40 °C for 48 h (GE40/48) has the largest work function. Furthermore, an electron-cloud potential-well model is established to explain the mechanism of electron emission-dominated charge transfer and assemble a triboelectric device to verify experimentally its conclusions. It is found that GE40/48 has the best performance with a 281 V open-circuit voltage, 9.7 µA short-current current, and storing 1.019 µC of charge, which is consistent with the model. Last, a patterned TENG is demonstrated for self-powered human–machine interaction application. This finding enhances the understanding of the inherent mechanism between the surface structure and the output performance of MXene-based TENG, which can be applied to other TENG based on 2D materials. 相似文献
126.
Xingying Zhang Chen Song Huijia Nong Kaige Xu Xiaozhuo Wu Wen Zhong Malcolm Xing Leyu Wang 《Advanced functional materials》2023,33(32):2300866
A conductive engineered cardiac patch (ECP) can reconstruct the biomimetic regenerative microenvironment of an infarcted myocardium. Direct ink writing (DIW) and 3D printing can produce an ECP with precisely controlled microarchitectures. However, developing a printed ECP with high conductivity and flexibility for gapless attachment to conform to epicardial geometry remains a challenge. Herein, an asymmetrical DIW hydrophobic/hydrophilic membrane using heat-processed graphene oxide (GO) ink is developed. The “Masked spin coating” method is also developed that leads to a microscale GO (hydrophilic)/reduced GO (rGO, hydrophobic) physiological sensor, as well as a macroscale moisture-driven GO/rGO actuator. Depositing mussel-inspired polydopamine (PDA) coating on the one side of the DIW rGO , the ultrathin (approximately 500 nm) PDA-rGO (hydrophilic)/rGO (hydrophobic) microlattice (DrGOM) ECP is bestowed with the flexibility and moisture-responsive actuation that allows gapless attachment to the curved surface of the epicardium. Conformable DrGOM exhibits a promising therapeutic effect on rats' infarcted hearts through conductive microenvironment reconstruction and improved neovascularization. 相似文献
127.
In this paper, a dual-band and reflective polarization converter based on metasurface is proposed. Its unit cell is composed of two layers of metal plates separated by a dielectric substrate. The simulation results show that the proposed converter is able to convert x- or y-polarized incident waves into cross-polarized waves perfectly in frequency bands of 6.75—10.59 GHz and 17.78—19.61 GHz, and the polarization conversion ratio (PCR) is nearly 100%, which can also convert linearly polarized waves into circularly polarized waves at four frequencies. It can be widely used in applications of radar satellites, antenna design and telecommunication with the function of realizing polarization conversion in two bands and achieving high PCR simultaneously. 相似文献
128.
Zhao-Yang Yin Yang Chen Yang-Yang Zhang Yu Yuan Qian Yang Ya-Nan Zhong Xu Gao Jing Xiao Zhao-Kui Wang Jian-Long Xu Sui-Dong Wang 《Advanced functional materials》2023,33(33):2302199
Minimizing reverse bias dark current density (Jdark) while retaining high external quantum efficiency is crucial for promising applications of perovskite photodiodes, and it remains challenging to elucidate the ultimate origin of Jdark. It is demonstrated in this study that the surface defects induced by iodine vacancies are the main cause of Jdark in perovskite photodiodes. In a targeted way, the surface defects are thoroughly passivated through a simple treatment with butylamine hydroiodide to form ultrathin 2D perovskite on its 3D bulk. In the passivated perovskite photodiodes, Jdark as low as 3.78 × 10-10 A cm-2 at -0.1 V is achieved, and the photoresponse is also enhanced, especially at low light intensities. A combination of the two improvements realizes high specific detectivity up to 1.46 × 1012 Jones in the devices. It is clarified that the trap states induced by the surface defects can not only raise the generation-recombination current density associated with the Shockley–Read–Hall mechanisms in the dark (increasing Jdark), but also provide additional carrier recombination paths under light illumination (decreasing photocurrent). The critical role of surface defects on Jdark of perovskite photodiodes suggests that making trap-free perovskite thin films, for example, by fine preparation and/or surface engineering, is a top priority for high-performance perovskite photodiodes. 相似文献
129.
Tianhao Wu Xu Zhang Yinzhong Wang Nian Zhang Haifeng Li Yong Guan Dongdong Xiao Shiqi Liu Haijun Yu 《Advanced functional materials》2023,33(4):2210154
As one of the high-energy cathode materials of lithium-ion batteries (LIBs), lithium-rich-layered oxide with “single-crystal” characteristic (SC-LLO) can effectively restrain side reactions and cracks due to the reduced inner boundaries and enhanced mechanical stabilities. However, there are still high challenges for SC-LLO with diverse performance requirements, especially on their cycle stability improvement. Herein, a novel concentration gradient “single-crystal” LLO (GSC-LLO), with gradually decreasing Mn and increasing Ni contents from center to surface, is designed and prepared by combining co-precipitation and molten-salt sintering methods, yielding a capacity retention of 97.6% and an energy density retention of 95.8% within 100 cycles at 0.1 C. The enhanced performance is mostly attributed to the gradient-induced stabilized structure, free of cracks and less spinel-like structure formation after long-term cycling. Furthermore, the gradient design is also beneficial to the safety of LLOs as suggested by the improved thermal stability and reduced gas release. This study provides an effective strategy to prepare high-energy, high-stability, and high-safety LLOs for advanced LIBs. 相似文献
130.
Yuanyuan Meng Chang Liu Ruikun Cao Jiasen Zhang Lin Xie Mengjin Yang Lisha Xie Yaohua Wang Xu Yin Cuirong Liu Ziyi Ge 《Advanced functional materials》2023,33(28):2214788
With rapid development of photovoltaic technology, flexible perovskite solar cells (f-PSCs) have attracted much attention for their light weight, high flexibility and portability. However, the power conversion efficiency (PCE) achieved so far is not yet comparable to that of rigid devices. This is mainly due to the great challenge of depositing homogeneous and high-quality perovskite films on flexible substrate. In this study, the pre-buried 3-aminopropionic acid hydroiodide (3AAH) additives into the electron transport layer (ETL) and modified the ETL/perovskite (PVK) interface by a bottom-up strategy. 3AAH treatment induced a templated perovskite grain growth and improved the quality of the ETL. By this, the residual stresses generated in PVK during the annealing-cooling process are released and converted into micro-compressive stresses. As a result, the defect density of f-PSCs with pre-buried 3AAH is reduced and the photovoltaic performance is greatly improved, reaching an exceptional PCE of 23.36%. This strategy provides a new idea to bridge the gap between flexible and rigid devices. 相似文献