全文获取类型
收费全文 | 100243篇 |
免费 | 8052篇 |
国内免费 | 4343篇 |
专业分类
电工技术 | 5654篇 |
技术理论 | 6篇 |
综合类 | 6302篇 |
化学工业 | 16700篇 |
金属工艺 | 6272篇 |
机械仪表 | 6985篇 |
建筑科学 | 8093篇 |
矿业工程 | 3421篇 |
能源动力 | 2929篇 |
轻工业 | 6402篇 |
水利工程 | 1672篇 |
石油天然气 | 7356篇 |
武器工业 | 806篇 |
无线电 | 10735篇 |
一般工业技术 | 11699篇 |
冶金工业 | 4931篇 |
原子能技术 | 1018篇 |
自动化技术 | 11657篇 |
出版年
2024年 | 460篇 |
2023年 | 1792篇 |
2022年 | 3150篇 |
2021年 | 4305篇 |
2020年 | 3331篇 |
2019年 | 2705篇 |
2018年 | 2933篇 |
2017年 | 3312篇 |
2016年 | 3051篇 |
2015年 | 4136篇 |
2014年 | 4944篇 |
2013年 | 5882篇 |
2012年 | 6335篇 |
2011年 | 6779篇 |
2010年 | 5813篇 |
2009年 | 5555篇 |
2008年 | 5411篇 |
2007年 | 5128篇 |
2006年 | 5443篇 |
2005年 | 4729篇 |
2004年 | 3026篇 |
2003年 | 2861篇 |
2002年 | 2676篇 |
2001年 | 2428篇 |
2000年 | 2355篇 |
1999年 | 2670篇 |
1998年 | 2102篇 |
1997年 | 1750篇 |
1996年 | 1710篇 |
1995年 | 1428篇 |
1994年 | 1163篇 |
1993年 | 745篇 |
1992年 | 650篇 |
1991年 | 438篇 |
1990年 | 354篇 |
1989年 | 304篇 |
1988年 | 227篇 |
1987年 | 151篇 |
1986年 | 123篇 |
1985年 | 70篇 |
1984年 | 53篇 |
1983年 | 44篇 |
1982年 | 41篇 |
1981年 | 29篇 |
1980年 | 25篇 |
1979年 | 16篇 |
1978年 | 1篇 |
1965年 | 1篇 |
1959年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
101.
压缩应力下(Tb,Dy)Fe2磁致伸缩的研究 总被引:5,自引:0,他引:5
本文利用自制的磁致伸缩测量仪和“jump”效应测量仪研究了在一定压强了多晶(Tb、Dy)Fe2棒的磁致伸缩,发现加压时,在一定工艺条件下制作的(Tb、Dy)Fe2棒会有磁致伸缩的变化。卸载后经过热处理,磁致伸缩值在不加压时也会维持一个高值。 相似文献
102.
We have shown that dicyanogold(I), [Au(CN)(2)](-) is a common metabolite found in blood and urine samples of patients treated with different gold based drugs. Some patients have high levels of gold within their red blood cells (RBCs). Size exclusion and C18 reversed phase chromatography show that the majority of the gold in RBC lysates is bound to protein, but small molecules such as dicyanogold(I) and gold-glutathione complexes are also present. Dicyanogold incubation with red blood cells in vitro leads to a rapid and complete uptake of gold. This uptake is unaffected by DIDS, an inhibitor of the anion channel, but is blocked by the addition of external cyanide. Dicyanogold is also readily taken up by H9 cells, a continuous CD(4+) cell line. This uptake is significantly inhibited by N-ethylmaleimide, suggesting a requirement for sulfhydryl groups. Dicyanogold inhibits the replication of the AIDS virus, HIV, in a cell culture model. 相似文献
103.
To our knowledge the concept of an angular conserved grating-pair dispersion compensation system is proposed for the first time, and furthermore a model of such a system is developed and applied to the study of two- and three-lens special cases. A set of easy-to-use dispersion compensation formulas based on geometric optics has been derived and confirmed by our experimental results. Tunability and a compensation ratio as high as 27,600 have been achieved with two- and three-lens systems, respectively. 相似文献
104.
We report a simple scheme for sensitive measurements of optical-noise spectra. Optical noise is separated from electronic noise when the output of an analog spectrum analyzer is real-time squared and then lock-in detected. This method directly yields the desired mean-square noise voltage, i.e., the power spectrum of the optical noise on a linear scale. To demonstrate this technique, the mean-square shot noise of a laser beam is measured and found to vary linearly with the laser power from several milliwatts down to one microwatt, in excellent quantitative agreement with predictions. 相似文献
105.
Qin Yang Bingqing Ge Pei Yuan Shuting Luo Hongwei Zhang Zhengyu Zhao Jiujun Zhang Shidong Wang Xiaojun Bao Xiangdong Yao 《Advanced functional materials》2023,33(25):2214588
Electrocatalytic hydrogenation (ECH) is a burgeoning strategy for the sustainable utilization of hydrogen. However, how to effectively suppress the competitive hydrogen evolution reaction (HER) is a big challenge to ECH catalysis. In this study, amine (NH2 R)-coordinated Pd nanoparticles loaded on carbon felt (Pd@CF) as a catalyst is successfully synthesized by a one-step solvothermal reduction method using oleylamine as the reducing agent. An exceptional ECH reactivity on benzaldehyde is achieved on the optimal Pd@CF catalyst in terms of a high conversion (89.7%) and selectivity toward benzyl alcohol (89.8%) at −0.4 V in 60 min. Notably, the Faradaic efficiency for producing benzyl alcohol is up to 90.2%, much higher than that catalyzed by Pd@CF-without N-group (41.1%) and thecommercial Pd/C (20.9%). The excellent ECH performance of Pd@CF can be attributed to the enriched electrons on Pd surface resulted from the introduction of NH2 R groups, which strengthens both the adsorption of benzaldehyde and the adsorbed hydrogen (Hads) on Pd, preventing the combination of Hads to form H2, that is, inhibiting the HER. This study gives a new insight into design principles of highly efficient electrocatalysts for the hydrogenation of unsaturated aldehydes molecules. 相似文献
106.
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
107.
Hui Zhang Yinkun Sun Junjie Yang Zhiyu Sun Yanxin Zhao Xin Li Wei Wang Dongwei Lu Jun Ma 《Advanced functional materials》2023,33(40):2302816
Precise adjustment of the pore size, damage repair, and efficient cleaning is all challenges for the wider application of inorganic membranes. This study reports a simple strategy of combining dry-wet spinning and electrosynthesis to fabricate stainless-steel metal–organic framework composite membranes characterized by customizable pore sizes, targeted reparability, and high catalytic activity for membrane cleaning. The membrane pore size can be precisely customized in the range of 14–212 nm at nanoscale, and damaged membranes can be repaired by targeted treatment in 120 s. In addition, advanced oxidation processes can be used to quickly clean the membrane and achieve 98% flux recovery. The synergistic actions of the membrane matrix and the selective layer increase the adsorption energy of active sites to oxidant, shorten the electron transfer cycle, and enhance the overall catalytic performance. This study can provide a new direction for the development of advanced membranes for water purification and high-efficiency membrane cleaning methods. 相似文献
108.
Neural Computing and Applications - High-resolution (HR) remote sensing images provide rich information for human activities. However, processing entire HR images is time-consuming, and many... 相似文献
109.
Neural Computing and Applications - Considering some problems of local linear embedding methods in semi-supervised scenarios, a robust scheme for generating soft labels is designed and a... 相似文献
110.
Jine Zhang Xiaobing Chen Mengqin Wang Qinghua Zhang Wenxiao Shi Xiaozhi Zhan Meng Zhao Zhe Li Jie Zheng Hui Zhang Furong Han Huaiwen Yang Tao Zhu Banggui Liu Fengxia Hu Baogen Shen Yuansha Chen Yue Zhang Yunzhong Chen Weisheng Zhao Jirong Sun 《Advanced functional materials》2023,33(41):2306434
Ferromagnetic materials with a strong spin-orbit coupling (SOC) have attracted much attention in recent years because of their exotic properties and potential applications in energy-efficient spintronics. However, such materials are scarce in nature. Here, a proximity-induced paramagnetic to ferromagnetic transition for the heavy transition metal oxide CaRuO3 in (001)-(LaMnO3/CaRuO3) superlattices is reported. Anomalous Hall effect is observed in the temperature range up to 180 K. Maximal anomalous Hall conductivity and anomalous Hall angle are as large as ∼15 Ω−1 cm−1 and ∼0.93%, respectively, by one to two orders of magnitude larger than those of the typical 3d ferromagnetic oxides such as La0.67Sr0.33MnO3. Density functional theory calculations indicate the existence of avoid band crossings in the electronic band structure of the ferromagnetic CRO layer, which enhances Berry curvature thus strong anomalous Hall effects. Further evidences from polarized neutron reflectometry show that the CaRuO3 layers are in a fully ferromagnetic state (∼0.8 μB/Ru), in sharp contrast to the proximity-induced canted antiferromagnetic state in 5d oxides SrIrO3 and CaIrO3 (∼0.1 μB/Ir). More than that, the magnetic anisotropy of the (001)-(LaMnO3/CaRuO3) superlattices is eightfold symmetric, showing potential applications in the technology of multistate data storage. 相似文献