全文获取类型
收费全文 | 21276篇 |
免费 | 2384篇 |
国内免费 | 711篇 |
专业分类
电工技术 | 365篇 |
综合类 | 337篇 |
化学工业 | 8211篇 |
金属工艺 | 538篇 |
机械仪表 | 722篇 |
建筑科学 | 229篇 |
矿业工程 | 41篇 |
能源动力 | 3381篇 |
轻工业 | 1842篇 |
水利工程 | 14篇 |
石油天然气 | 24篇 |
武器工业 | 10篇 |
无线电 | 3306篇 |
一般工业技术 | 3898篇 |
冶金工业 | 421篇 |
原子能技术 | 335篇 |
自动化技术 | 697篇 |
出版年
2024年 | 80篇 |
2023年 | 852篇 |
2022年 | 2492篇 |
2021年 | 2660篇 |
2020年 | 1218篇 |
2019年 | 1017篇 |
2018年 | 863篇 |
2017年 | 955篇 |
2016年 | 1018篇 |
2015年 | 986篇 |
2014年 | 1281篇 |
2013年 | 1353篇 |
2012年 | 1251篇 |
2011年 | 1665篇 |
2010年 | 1083篇 |
2009年 | 963篇 |
2008年 | 821篇 |
2007年 | 755篇 |
2006年 | 562篇 |
2005年 | 435篇 |
2004年 | 321篇 |
2003年 | 272篇 |
2002年 | 258篇 |
2001年 | 219篇 |
2000年 | 155篇 |
1999年 | 82篇 |
1998年 | 158篇 |
1997年 | 102篇 |
1996年 | 73篇 |
1995年 | 44篇 |
1994年 | 55篇 |
1993年 | 33篇 |
1992年 | 35篇 |
1991年 | 44篇 |
1990年 | 33篇 |
1989年 | 31篇 |
1988年 | 16篇 |
1987年 | 20篇 |
1986年 | 18篇 |
1985年 | 24篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 12篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1975年 | 3篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
现有的蠕虫检测方法大多通过关闭不安全的端口,切断感染主机与未感染主机之间通信等方法延缓蠕虫传播而达到将损害减少到最低程度的目的.实际上在实施这些方法时往往有许多障碍需要克服,其中的最大障碍就是存在错误检测率高的问题.现将免疫危险理论中的DCs(树突状细胞,Dendritic Cells)-T细胞协同机制用于蠕虫检测,其中DCs属于先天免疫系统细胞,T细胞属于适应性免疫系统细胞.本模型将蠕虫进程触发的系统调用序列当作抗原,将感染蠕虫导致的主机和网络异常当作危险信号.在该模型中,DCs负责危险信号的收集检测并提呈与该危险信号关联的抗原给T细胞检测器进行抗原结构检测.理论分析说明,这样的双重检测方法可以降低伪肯定率和伪否定率,并且记忆T细胞检测器的采用能使系统对类似蠕虫的再次感染反应更加迅速. 相似文献
22.
RADIOIMMUNOTOXICOLOGICALEFFECTOFENRICHEDURANIUMONCENTRALANDPERIPHERALIMMUNECELLSANDTHEPROTECTIVEACTIONOFIL-1ANDIL-2¥ZhuShoupe... 相似文献
23.
Chuanming Tian Bin Li Yichuan Rui Hao Xiong Yu Zhao Xuefei Han Xinliang Zhou Yu Qiu Wei An Kerui Li Chengyi Hou Yaogang Li Hongzhi Wang Qinghong Zhang 《Advanced functional materials》2023,33(41):2302270
Despite the outstanding power conversion efficiency (PCE) of perovskite solar cells (PSCs) achieved over the years, unsatisfactory stability and lead toxicity remain obstacles that limit their competitiveness and large-scale practical deployment. In this study, in situ polymerizing internal encapsulation (IPIE) is developed as a holistic approach to overcome these challenges. The uniform polymer internal package layer constructed by thermally triggered cross-linkable monomers not only solidifies the ionic perovskite crystalline by strong electron-withdrawing/donating chemical sites, but also acts as a water penetration and ion migration barrier to prolong shelf life under harsh environments. The optimized MAPbI3 and FAPbI3 devices with IPIE treatment yield impressive efficiencies of 22.29% and 24.12%, respectively, accompanied by remarkably enhanced environmental and mechanical stabilities. In addition, toxic water-soluble lead leakage is minimized by the synergetic effect of the physical encapsulation wall and chemical chelation conferred by the IPIE. Hence, this strategy provides a feasible route for preparing efficient, stable, and eco-friendly PSCs. 相似文献
24.
Dongsheng Xie Yue Zhang Xiyue Yuan Youle Li Fei Huang Yong Cao Chunhui Duan 《Advanced functional materials》2023,33(11):2212601
Semitransparent organic solar cells (ST-OSCs) have attracted increasing attention due to their promising prospect in building-integrated photovoltaics. Generally, efficient ST-OSCs with good average visible transmittance (AVT) can be realized by developing active layer materials with light absorption far from the visible light range. Herein, the development of ultrawide bandgap polymer donors with near-ultraviolet absorption, paired with near-infrared acceptors, is proposed to achieve high-performance ST-OSCs. The key points for the design of ultrawide bandgap polymers include constructing donor–donor type conjugated skeleton, suppressing the quinoidal resonance effect, and minimizing the twist of conjugated skeleton via noncovalent conformational locks. As a proof of concept, a polymer named PBOF with an optical bandgap of 2.20 eV is synthesized, which exhibited largely reduced overlap with the human eye photopic response spectrum and afforded a power conversion efficiency (PCE) of 16.40% in opaque device. As a result, ST-OSCs with a PCE over 10% and an AVT over 30% are achieved without optical modulation. Moreover, colorful ST-OSCs with visual aesthetics can be achieved by tuning the donor/acceptor weight ratio in active layer benefiting from the ultrawide bandgap nature of PBOF. This study demonstrates the great potential of ultrawide bandgap polymers for efficient colorful ST-OSCs. 相似文献
25.
Ruiqi Li Lian Chen Qin Ji Qing Liang Ying Zhu Wei Fu Tianyou Chen Hongwei Duan Wenshan He Zushun Xu Xiaofang Dai Jinghua Ren 《Advanced functional materials》2023,33(37):2213292
Radiotherapy is identified as a crucial treatment for patients with glioblastoma, but recurrence is inevitable. The efficacy of radiotherapy is severely hampered partially due to the tumor evolution. Growing evidence suggests that proneural glioma stem cells can acquire mesenchymal features coupled with increased radioresistance. Thus, a better understanding of mechanisms underlying tumor subclonal evolution may develop new strategies. Herein, data highlighting a positive correlation between the accumulation of macrophage in the glioblastoma microenvironment after irradiation and mesenchymal transdifferentiation in glioblastoma are presented. Mechanistically, elevated production of inflammatory cytokines released by macrophages promotes mesenchymal transition in an NF-κB-dependent manner. Hence, rationally designed macrophage membrane-coated porous mesoporous silica nanoparticles (MMNs) in which therapeutic anti-NF-κB peptides are loaded for enhancing radiotherapy of glioblastoma are constructed. The combination of MMNs and fractionated irradiation results in the blockage of tumor evolution and therapy resistance in glioblastoma-bearing mice. Intriguingly, the macrophage invasion across the blood-brain barrier is inhibited competitively by MMNs, suggesting that these nanoparticles can fundamentally halt the evolution of radioresistant clones. Taken together, the biomimetic MMNs represent a promising strategy that prevents mesenchymal transition and improves therapeutic response to irradiation as well as overall survival in patients with glioblastoma. 相似文献
26.
Colon cancer is the third most commonly diagnosed cancer in the world. Most colon AdenoCArcinoma (ACA) arises from pre-existing benign polyps in the mucosa of the bowel. Thus, detecting benign at the earliest helps reduce the mortality rate. In this work, a Predictive Modeling System (PMS) is developed for the classification of colon cancer using the Horizontal Voting Ensemble (HVE) method. Identifying different patterns in microscopic images is essential to an effective classification system. A twelve-layer deep learning architecture has been developed to extract these patterns. The developed HVE algorithm can increase the system’s performance according to the combined models from the last epochs of the proposed architecture. Ten thousand (10000) microscopic images are taken to test the classification performance of the proposed PMS with the HVE method. The microscopic images obtained from the colon tissues are classified into ACA or benign by the proposed PMS. Results prove that the proposed PMS has ~8% performance improvement over the architecture without using the HVE method. The proposed PMS for colon cancer reduces the misclassification rate and attains 99.2% of sensitivity and 99.4% of specificity. The overall accuracy of the proposed PMS is 99.3%, and without using the HVE method, it is only 91.3%. 相似文献
27.
Cancer Multidrug Resistance: Safe and Effective Reversal of Cancer Multidrug Resistance Using Sericin‐Coated Mesoporous Silica Nanoparticles for Lysosome‐Targeting Delivery in Mice (Small 9/2017) 下载免费PDF全文
28.
采用聚3,4-乙烯二氧噻吩(PEDOT)/FTO为对电极,研究了合成介质对循环伏安法电聚合制备的PEDOT/FTO对电极性能的影响。通过SEM、CV、EIS、Tafel曲线,并首次采用SECM方法对所制备的对电极的电催化性能进行了表征。结果表明:在LiClO4水溶液和1-丁基-3-甲基四氟硼酸盐离子液体(IL)中制备的光阴极具有良好的电催化性能。J-V测试曲线表明,在LiClO4水溶液和IL中制备的光阴极所组装的DSSC器件的光电转化效率分别达6.4%和6.6%,接近于同等条件下以Pt对电极构建的DSSC器件的光电转化效率。 相似文献
29.
A Two‐Stage Annealing Strategy for Crystallization Control of CH3NH3PbI3 Films toward Highly Reproducible Perovskite Solar Cells 下载免费PDF全文
Jing Zhang Wensheng Liang Wei Yu Shuwen Yu Yiliang Wu Xin Guo Shengzhong Liu Can Li 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(26)
The solvent‐engineering method is widely used to fabricate top‐performing perovskite solar cells, which, however, usually exhibit inferior reproducibility. Herein, a two‐stage annealing (TSA) strategy is demonstrated for processing of perovskite films, namely, annealing the intermediate phase at 60 °C for the first stage then at 100 °C for the second stage. Compared to conventional direct annealing temperature (DHA) at 100 °C, using this strategy, MAPbI3 films become more controllable, leading to superior film uniformity and device reproducibility with the champion device efficiency reaching 19.8%. More specifically, the coefficient of variation of efficiency for 49 cells is reduced to 5.9%, compared to 9.8% for that using DHA. The TSA process is carefully studied using Fourier transform infrared spectroscopy, X‐ray diffraction, and UV–vis absorption spectroscopy. It is found that in comparison with DHA the formation of hydrogen bonding and crystallization of perovskite are much slower and can be better controlled when using TSA. The improvements in film uniformity and device reproducibility are attributed to: 1) controllable MAPbI3 crystal growth stemming from the progressive formation of hydrogen bonding between methylammonium and halide; 2) suppression of intermediate phase film dewetting, which is believed to be due to its decreased mobility at the initial low‐temperature annealing stage. 相似文献
30.
Jiabin Liu Jiawei Deng Yangyang Zhu Xiaokang Geng Lifu Zhang Sang Young Jeong Dan Zhou Han Young Woo Dong Chen Feiyan Wu Lie Chen 《Advanced materials (Deerfield Beach, Fla.)》2023,35(1):2208008
With the great potential of the all-polymer solar cells for large-area wearable devices, both large-area device efficiency and mechanical flexibility are very critical but attract limited attention. In this work, from the perspective of the polymer configurations, two types of terpolymer acceptors PYTX-A and PYTX-B (X = Cl or H) are developed. The configuration difference caused by the replacement of non-conjugated units results in distinct photovoltaic performance and mechanical flexibility. Benefiting from a good match between the intrinsically slow film-forming of the active materials and the technically slow film-forming of the blade-coating process, the toluene-processed large-area (1.21 cm2) binary device achieves a record efficiency of 14.70%. More importantly, a new parameter of efficiency stretchability factor (ESF) is proposed for the first time to comprehensively evaluate the overall device performance. PM6:PYTCl-A and PM6:PYTCl-B yield significantly higher ESF than PM6:PY-IT. Further blending with non-conjugated polymer donor PM6-A, the best ESF of 3.12% is achieved for PM6-A:PYTCl-A, which is among the highest comprehensive performances. 相似文献