全文获取类型
收费全文 | 64690篇 |
免费 | 5168篇 |
国内免费 | 2846篇 |
专业分类
电工技术 | 3676篇 |
技术理论 | 7篇 |
综合类 | 4259篇 |
化学工业 | 11062篇 |
金属工艺 | 3605篇 |
机械仪表 | 3961篇 |
建筑科学 | 5464篇 |
矿业工程 | 1859篇 |
能源动力 | 1880篇 |
轻工业 | 4065篇 |
水利工程 | 1166篇 |
石油天然气 | 4532篇 |
武器工业 | 456篇 |
无线电 | 7093篇 |
一般工业技术 | 8046篇 |
冶金工业 | 3118篇 |
原子能技术 | 727篇 |
自动化技术 | 7728篇 |
出版年
2024年 | 231篇 |
2023年 | 1045篇 |
2022年 | 1749篇 |
2021年 | 2464篇 |
2020年 | 1905篇 |
2019年 | 1665篇 |
2018年 | 1877篇 |
2017年 | 2111篇 |
2016年 | 1921篇 |
2015年 | 2380篇 |
2014年 | 3231篇 |
2013年 | 3688篇 |
2012年 | 4105篇 |
2011年 | 4438篇 |
2010年 | 3890篇 |
2009年 | 3693篇 |
2008年 | 3619篇 |
2007年 | 3522篇 |
2006年 | 3576篇 |
2005年 | 3092篇 |
2004年 | 2099篇 |
2003年 | 1884篇 |
2002年 | 1654篇 |
2001年 | 1608篇 |
2000年 | 1664篇 |
1999年 | 1785篇 |
1998年 | 1395篇 |
1997年 | 1174篇 |
1996年 | 1055篇 |
1995年 | 949篇 |
1994年 | 769篇 |
1993年 | 559篇 |
1992年 | 435篇 |
1991年 | 337篇 |
1990年 | 314篇 |
1989年 | 228篇 |
1988年 | 177篇 |
1987年 | 109篇 |
1986年 | 104篇 |
1985年 | 60篇 |
1984年 | 41篇 |
1983年 | 26篇 |
1982年 | 33篇 |
1981年 | 22篇 |
1980年 | 13篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Keqi He Xiangdong Wang Junting Yu Haigang Jiang Guangshan Xie Hua Tan Yu Liu Dongge Ma Yafei Wang Weiguo Zhu 《Organic Electronics》2014,15(11):2942-2949
To explore the influence of push–pull chromophores on properties of emitter in organic light-emitting devices (OLEDs), an acceptor–donor–acceptor (A–D–A)-based dinuclear iridium (III) complex of (dfppy)4Ir2(dipic-FL) was synthesized via Suzuki coupling reaction, in which dfppy is 2-(2,4-difluorophenyl)pyridine and dipic-FL is 2,7-di(5-pyridyl-2-carboxyl)-9,9-dioctyl-9H-fluorene. An intense emission peak at about 480 nm resulting from the (dfppy)2Ir(pic) chromophore and a weak long-wavelength emission band at 580–660 nm attributed to intramolecular charge transfer transition were exhibited for (dfppy)4Ir2(dipic-FL) in dichloromethane solution. But a remarkably hypsochromic photoluminescence profile with an intense characteristical emission peak at 422 nm was observed, which is attributed to the intraligand (IL) π–π∗ excited states in its thin film. White emission with a maximum luminance of 1040 cd/m2 and current efficiency of 1.2 cd/A was obtained in its single-emissive-layer (SEL) OLEDs with a configuration of ITO/PEDOT:PSS/(dfppy)4Ir2(dipic-FL) (10 wt%):TCTA/TPBi/LiF/Al. To our knowledge, this is one of the best examples in term of dinuclear iridium complex as single dopant in the high-performance white-emitting SEL-OLEDs. 相似文献
993.
优质的学习资源是保障远程教育质量的重要基石,如何对学习资源进行有效的监控,是远程教育亟需解决的问题,本文结合目前远程教育中学习资源的现状和不足,提出了运用软件工程的思想,基于B/S模式,建立学习资源质量监控系统,以此更好的提高对当前远程教学资源的使用和质量评估。 相似文献
994.
Parallel-coupled microstrip filters are designed to suppress spurious response at twice the passband frequency (2f/sub o/) with a uniform dielectric overlay. The overlay dielectric is used to equalize the modal phase velocities of each coupled stage. Based on the method, we have a large degree of freedom in choosing thickness and permittivity of the overlay dielectric. The image impedances of all the coupled stages in such a filter need adjusting to complete the filter synthesis. Two filters are fabricated and measured results show a good agreement with the simulation. A suppression of at least 40 dB to the spurious responses at 2f/sub o/ is achieved. 相似文献
995.
996.
This paper deals with the two dimensional (2-D) infrared photonic crystal slab with an air-bridge structure featuring defect waveguides in which the optical propagation properties were obtained by measurements of transmission spectra. 3-D finite-difference time-domain (FDTD) simulations have revealed the appearance of four defect propagation modes for the band structure and transmission spectra in the air-bridge slab. These defect modes were experimentally identified in the measured transmission spectra. 相似文献
997.
Sisi Liu Chongjian Zhang Shuangyuan Li Yong Xia Kang Wang Kao Xiong Haodong Tang Linyuan Lian Xinxing Liu Ming-Yu Li Manlin Tan Liang Gao Guangda Niu Huan Liu Haisheng Song Daoli Zhang Jianbo Gao Xinzheng Lan Kai Wang Xiao Wei Sun Ye Yang Jiang Tang Jianbing Zhang 《Advanced functional materials》2021,31(9):2006864
Lead chalcogenide quantum dot (QD) infrared (IR) solar cells are promising devices for breaking through the theoretical efficiency limit of single-junction solar cells by harvesting the low-energy IR photons that cannot be utilized by common devices. However, the device performance of QD IR photovoltaic is limited by the restrictive relation between open-circuit voltages (VOC) and short circuit current densities (JSC), caused by the contradiction between surface passivation and electronic coupling of QD solids. Here, a strategy is developed to decouple this restriction via epitaxially coating a thin PbS shell over the PbSe QDs (PbSe/PbS QDs) combined with in situ halide passivation. The strong electronic coupling from the PbSe core gives rise to significant carrier delocalization, which guarantees effective carrier transport. Benefited from the protection of PbS shell and in situ halide passivation, excellent trap-state control of QDs is eventually achieved after the ligand exchange. By a fine control of the PbS shell thickness, outstanding IR JSC of 6.38 mA cm−2 and IR VOC of 0.347 V are simultaneously achieved under the 1100 nm-filtered solar illumination, providing a new route to unfreeze the trade-off between VOC and JSC limited by the photoactive layer with a given bandgap. 相似文献
998.
Ming Zhang Xuefeng Jiang Qicheng Zhang Tao Zheng Mohsen Mohammadniaei Wentao Wang Jian Shen Yi Sun 《Advanced functional materials》2021,31(38):2102274
Immunotherapy is an efficient approach to clinical oncology. However, the immune privilege of the central nervous system (CNS) limits the application of immunotherapeutic strategies for brain cancers, especially glioblastoma (GBM). Tumor resistance to immune checkpoint inhibitors is a further challenge in immunotherapies. To overcome the immunological tolerance of brain tumors, a novel multifunctional nanoparticle (NP) for highly efficient synergetic immunotherapy is reported. The NP contains an anti-PDL1 antibody (aPDL1), upconverting NPs, and the photosensitizer 5-ALA; the surface of the NP is conjugated with the B1R kinin ligand to facilitate transport across the blood-tumor-barrier. Upon irradiation with a 980 nm laser, 5-ALA is transformed into protoporphyrin IX, generating reactive oxygen species. Photodynamic therapy (PDT) further promotes intratumoral infiltration of cytotoxic T lymphocytes and sensitizes tumors to PDL1 blockade therapy. It is demonstrated that combining PDT and aPDL1 can effectively suppress GBM growth in mouse models. The proposed NPs provide a novel and effective strategy for boosting anti-GBM photoimmunotherapy. 相似文献
999.
Jincheng Tang Kun Xi Hao Chen Lingjun Wang Dongya Li Yun Xu Tianwen Xin Liang Wu Yidi Zhou Jiang Bian Zhengwei Cai Huilin Yang Lianfu Deng Yong Gu Wenguo Cui Liang Chen 《Advanced functional materials》2021,31(38):2102465
Osteogenic glue that reproduces the natural bone composition represents the final frontier of orthopedic adhesives with the potential to revolutionize surgical strategies against comminuted fractures. However, it is difficult to achieve an all-in-one formula, which could provide flexible and reliable adhesiveness while avoiding interfering with or even promoting the healing of glued fractures. Herein, an osteogenic glue characterized by inorganic-in-organic integration between amine-modified mesoporous bioactive glass nanoparticles (AMBGN) and bioadhesive gelatin-dextran network (GelDex) is introduced as an all-in-one tool to flexibly adhere and splice bone fragments and subsequently guide fracture healing during degradation. Relying on such integration, a 4-fold improvement in cohesiveness is presented, followed by a nearly 5-fold enhancement in adhesive strength in ex vivo porcine bone samples. The reversible and re-adjustable adhesiveness also enables glue to effectively splice intricate fragments from highly comminuted fractures in the rabbit radius in an in vivo environment. Moreover, well-preserved organic–inorganic integrity during degradation of the glue guides sustained interfacial osteogenesis and achieve satisfying healing outcomes in glued fractures, as observed by the 2-fold improvement in biomechanical and radiological performance compared with commercially available cyanoacrylate adhesives. The current findings propose an all-in-one solution for the fixation of bone fragments during surgery. 相似文献
1000.
熊秋 《电子信息对抗技术》2010,25(1):15-20
基于四阶累积量的自适应参数型多径时延估计(FOC—APMTDE)算法只能直接估计整数倍采样间隔的时延,为了克服此缺点,引入遗传算法进行时延估计的寻优,保留了FOC—APMTDE算法良好的抑制相关或非相关高斯噪声的性能,在低信噪比的情况下可以准确地直接估计非整数倍采样间隔的时延。计算机仿真试验验证了新方法的有效性。 相似文献