全文获取类型
| 收费全文 | 39070篇 |
| 免费 | 3022篇 |
| 国内免费 | 905篇 |
专业分类
| 电工技术 | 2107篇 |
| 技术理论 | 6篇 |
| 综合类 | 2381篇 |
| 化学工业 | 6769篇 |
| 金属工艺 | 2349篇 |
| 机械仪表 | 2234篇 |
| 建筑科学 | 2742篇 |
| 矿业工程 | 1132篇 |
| 能源动力 | 1040篇 |
| 轻工业 | 2261篇 |
| 水利工程 | 592篇 |
| 石油天然气 | 2784篇 |
| 武器工业 | 247篇 |
| 无线电 | 4579篇 |
| 一般工业技术 | 4775篇 |
| 冶金工业 | 1645篇 |
| 原子能技术 | 590篇 |
| 自动化技术 | 4764篇 |
出版年
| 2025年 | 98篇 |
| 2024年 | 1030篇 |
| 2023年 | 852篇 |
| 2022年 | 1209篇 |
| 2021年 | 1725篇 |
| 2020年 | 1418篇 |
| 2019年 | 1240篇 |
| 2018年 | 1211篇 |
| 2017年 | 1334篇 |
| 2016年 | 1159篇 |
| 2015年 | 1465篇 |
| 2014年 | 1809篇 |
| 2013年 | 2192篇 |
| 2012年 | 2247篇 |
| 2011年 | 2475篇 |
| 2010年 | 2066篇 |
| 2009年 | 1880篇 |
| 2008年 | 1798篇 |
| 2007年 | 1712篇 |
| 2006年 | 1869篇 |
| 2005年 | 1672篇 |
| 2004年 | 1146篇 |
| 2003年 | 963篇 |
| 2002年 | 893篇 |
| 2001年 | 768篇 |
| 2000年 | 879篇 |
| 1999年 | 1058篇 |
| 1998年 | 818篇 |
| 1997年 | 729篇 |
| 1996年 | 713篇 |
| 1995年 | 575篇 |
| 1994年 | 476篇 |
| 1993年 | 363篇 |
| 1992年 | 277篇 |
| 1991年 | 199篇 |
| 1990年 | 154篇 |
| 1989年 | 139篇 |
| 1988年 | 113篇 |
| 1987年 | 70篇 |
| 1986年 | 55篇 |
| 1985年 | 26篇 |
| 1984年 | 19篇 |
| 1983年 | 22篇 |
| 1982年 | 30篇 |
| 1981年 | 17篇 |
| 1980年 | 12篇 |
| 1977年 | 6篇 |
| 1976年 | 2篇 |
| 1953年 | 4篇 |
| 1951年 | 3篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
971.
972.
水利水电工程征地移民搬迁后的生产生活恢复,不仅是实现移民规划目标的重点内容,也是保持安置区社会稳定的重要因素。水库移民搬迁后的收入恢复水平是评价移民工程搬迁安置效果的一个重要指标。移民收入的评价,除收入水平之外,还涉及到贫富差距等共同富裕问题。针对南水北调中线丹江口库区试点移民的收入恢复,在抽样与跟踪调查获取数据的基础上,分析了移民收入的整体恢复水平,并利用非均匀系数对收入的差距进行了研究。 相似文献
973.
974.
在软土地基上修建穿堤建筑物,基础处理是一个难点,基础设计的关键是解决变形协调的问题.广利电排站穿堤涵软土地基处理采用水泥粉煤灰碎石桩(CFG桩)复合地基技术.本文通过工程实例,介绍了穿堤涵软土地基设计以沉降控制为主的设计理念. 相似文献
975.
叶尔羌河径流主要由融化冰川积雪与降水补给,因此受季节气温影响极大,主要表现为年内分布极不均衡,春季3～5月只占年径流的7%,夏季6～8月占68.3%,秋季9～11月占18.5%,冬季12～2月占6.2%.洪枯流量变化大,含沙量大,推移质泥沙占年总输沙量的20%左右.人工弯道式引水枢纽可很好地解决引水与排沙的矛盾.在此将依干其渠首的设计做一简要的介绍,供参考. 相似文献
976.
Jiyuan Luo;Donghai Ding;Guoqing Xiao; 《Journal of the American Ceramic Society》2024,107(12):8474-8489
The mechanical properties at microlevels are of important meaning for refractories while determining these values is of great challenges. In this contribution, a tailored grid nanoindentation test was employed to determine the micromechanical properties of low-carbon Al2O3–C refractories featuring reduced brittleness with in situ magnesium aluminate spinel/carbon nanotubes (MgAl2O4/CNTs) compound interfacial layer between the aggregate and matrix. The micromechanical properties, especially Young's modulus (E) and specific fracture energy (Gc) of the aggregate, matrix, and aggregate/matrix interface area of the refractories, were determined and compared. Statistical analysis on the nanoindentation results of the aggregate and matrix in the reference sample and the sample with interfacial layer shows high consistency, which reveals the high feasibility of the method. The median microspecific fracture energy of the aggregate/matrix interface increases from 63.67 J m−2 of the reference group to 132.90 J m−2 of the sample with the compound interfacial layer, which means that higher energy is needed for the initiation and propagation of microcracks within the interfacial layer, accounting for the brittleness reduction of the refractories. Consistent conclusions were drawn from the nanoindentation test at microlevels along with the macrolevel thermal shock test and wedge splitting test. 相似文献
977.
Kai Zhou;Zonglin Pan;Xin Luo;Ping Yang;Pengfei Wang; 《Lubrication Science》2024,36(2):135-148
Minimising the friction force of the archwire-bracket sliding contact is crucial for achieving a high-quality orthodontic treatment. Micro-dimples and micro-grooves textures were successfully produced on the two slot surfaces of the stainless steel orthodontic brackets with the laser surface texturing technology. The effect of surface texture on reducing the friction and wear behaviour of the stainless steel archwire-bracket sliding contact combinations in artificial saliva environment was investigated. Friction coefficients of less than 0.15 and mild wear were obtained by using the three rows micro-grooves textured bracket with a width of 60 μm and a spacing of 150 μm. The friction and wear performance was further enhanced with the addition of orthodontic wax materials. It was strongly argued that the synergetic effects of the fabricated micro-grooves texture and the added orthodontic wax materials leading to the outstanding friction and wear behaviour of the archwire-bracket sliding contacts. 相似文献
978.
Chuanguang Wu;Xiaorong Yan;Haiping Yu;Jiakui Xiong;Hao Zhang;Tengfei Li;Guoqing Zhao;Guangcun Shan;Jinzhang Liu;Mingjun Hu;Jun Luo;Jun Yang; 《Small (Weinheim an der Bergstrasse, Germany)》2024,20(44):2403258
Inhibiting the shuttle of polysulfides is of great significance for promoting the practical application of lithium–sulfur batteries (LSBs). Here, an imine-linked covalent organic framework@carbon nanotube (COF@CNT) interlayer composed of triazine and boroxine rings is constructed between the sulfur cathode and the separator for polysulfides reception and reutilization. The introduction of CNT imparts the conductor characteristic to the interlayer attributed to electron tunneling in thin COF shell, and creates a hierarchical porous architecture for accommodating polysulfides. The uniform distribution of amphiphilic adsorption sites in COF microporous structure not only enables efficient entrapment of polysulfides while allowing the penetration of Li+ ions, but also provides a stable electrocatalytic channel for bidirectional conversion of active sulfur to achieve the substantially improved capacity and stability. The interlayer-incorporated LSBs deliver an ultrahigh capacity of 1446 mA g−1 at 0.1C and an ultralow capacity decay rate of 0.019% at 1C over 1500 cycles. Even at an electrolyte/sulfur ratio of 6 µL mg−1, an outstanding capacity of 995 mAh g−1 and capacity retention of 74.1% over 200 cycles at 0.2C are obtained. This work offers a compelling polysulfides entrapment and reactivation strategy for stimulating the study on ultra-stable LSBs. 相似文献
979.
Si Wang;Yingjie Wu;Mingbo Pu;Mingfeng Xu;Renyan Zhang;Tao Yu;Xiong Li;Xiaoliang Ma;Yuanjie Su;Huiling Tai;Yongcai Guo;Xiangang Luo; 《Small (Weinheim an der Bergstrasse, Germany)》2024,20(6):2305706
Developing versatile systems that can concurrently achieve energy saving and energy generation is critical to accelerate carbon neutrality. However, challenges on designing highly effective, large scale, and multifunctional photonic film hinder the concurrent combination of passive daytime radiative cooling (PDRC) and utilization of sustainable clean energies. Herein, a versatile scalable photonic film (Ecoflex@h-BN) with washable property and excellent mechanical stability is developed by combining the excellent scattering efficiency of the hexagonal boron nitride (h-BN) nanoplates with the high infrared emissivity and ideal triboelectric negative property of the Ecoflex matrix. Strikingly, sufficiently high solar reflectance (0.92) and ideal emissivity (0.97) endow the Ecoflex@h-BN film with subambient cooling effect of ≈9.5 °C at midday during the continuous outdoor measurements. In addition, the PDRC Ecoflex@h-BN film-based triboelectric nanogenerator (PDRC-TENG) exhibits a maximum peak power density of 0.5 W m−2. By reasonable structure design, the PDRC-TENG accomplishes effective wind energy harvesting and can successfully drive the electronic device. Meanwhile, an on-skin PDRC-TENG is fabricated to harvest human motion energy and monitor moving states. This research provides a novel design of a multifunctional PDRC photonic film, and offers a versatile strategy to realize concurrent PDRC and sustainable energies harvesting. 相似文献
980.
Xingyu Chen;Jiali Zhou;Jun Luo;Jiawei Zhang;Pengfei Qiu;Xun Shi; 《Small (Weinheim an der Bergstrasse, Germany)》2024,20(46):2405276
Halide perovskites are of great interest due to their exceptional optical and optoelectronic properties. However, thermal conductivity of many halide perovskites remains unexplored. In this study, an ultralow lattice thermal conductivity κL (0.24 W m−1 K−1 at 300 K) is reported and its weak temperature dependence (≈T−0.27) in an all-inorganic vacancy-ordered halide perovskite, Cs3Bi2Br9. The intrinsically ultralow κL can be attributed to the soft low-lying phonon modes with strong anharmonicity, which have been revealed by combining experimental heat capacity and Raman spectroscopy measurements, and first-principles calculations. It is shown that the highly anharmonic phonons originate from the Bi 6s2 lone pair expression with antibonding states of Bi 6s and Br 4p orbitals driven by the dynamic BiBr6 octahedral distortion. Theoretical calculations reveal that these low-energy phonons are mostly contributed by large Br motions induced dynamic distortion of BiBr6 octahedra and large Cs rattling motions, verified by the synchrotron X-ray pair distribution function analysis. In addition, the weak temperature dependence of κL can be traced to the wave-like tunneling of phonons, induced by the low-lying phonon modes. This work reveals the strong anharmonicity and wave-like tunneling of low-energy phonons for designing efficient vacancy-ordered halide perovskites with intrinsically low κL. 相似文献