全文获取类型
收费全文 | 11188篇 |
免费 | 1155篇 |
国内免费 | 397篇 |
专业分类
电工技术 | 293篇 |
综合类 | 939篇 |
化学工业 | 3936篇 |
金属工艺 | 457篇 |
机械仪表 | 434篇 |
建筑科学 | 1351篇 |
矿业工程 | 613篇 |
能源动力 | 405篇 |
轻工业 | 642篇 |
水利工程 | 387篇 |
石油天然气 | 778篇 |
武器工业 | 31篇 |
无线电 | 327篇 |
一般工业技术 | 582篇 |
冶金工业 | 848篇 |
原子能技术 | 235篇 |
自动化技术 | 482篇 |
出版年
2024年 | 34篇 |
2023年 | 143篇 |
2022年 | 319篇 |
2021年 | 364篇 |
2020年 | 437篇 |
2019年 | 370篇 |
2018年 | 332篇 |
2017年 | 375篇 |
2016年 | 403篇 |
2015年 | 442篇 |
2014年 | 667篇 |
2013年 | 735篇 |
2012年 | 923篇 |
2011年 | 857篇 |
2010年 | 693篇 |
2009年 | 716篇 |
2008年 | 556篇 |
2007年 | 740篇 |
2006年 | 650篇 |
2005年 | 530篇 |
2004年 | 437篇 |
2003年 | 390篇 |
2002年 | 307篇 |
2001年 | 255篇 |
2000年 | 208篇 |
1999年 | 167篇 |
1998年 | 123篇 |
1997年 | 115篇 |
1996年 | 84篇 |
1995年 | 65篇 |
1994年 | 51篇 |
1993年 | 35篇 |
1992年 | 36篇 |
1991年 | 31篇 |
1990年 | 25篇 |
1989年 | 15篇 |
1988年 | 10篇 |
1987年 | 25篇 |
1986年 | 15篇 |
1985年 | 18篇 |
1984年 | 20篇 |
1983年 | 11篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
In this study, the cost-effective graphite powder (GPd)-coated polyurethane (PGPd-PU) sponge hollow tube (PGPd-PUHT) was prepared for high-efficient continuous oil removal, the hydrophobicity-superoleophilicity PGPd-PU sponge was fabricated through a simple dip-coating method, which dipping PU sponge into GPd dispersion and drying, then coating polydimethylsiloxane (PDMS) on sponge skeleton, as-prepared sponge could selectively absorb a variety of oils up to 34 times of its own weight for dimethyl sulfoxide (DMSO). The PGPd-PUHT was prepared via wrapping PGPd-PU sponge on porous tubular support. The obtained PGPd-PUHT could continuously collect various types of oils from water surface with flux as high as 1.52 kL/m2h, and excellent separation efficiency (up to 97.7%) for toluene, as well as remarkable reusability. Moreover, a continuous floating oil collection device based on PGPd-PUHT was designed which showed excellent floating oil collection ability. In addition, our strategy possesses the advantages of low cost, simple preparation, highly efficient, and easily scale-up, showing a great potential for dealing with practical oil spill remediation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48921. 相似文献
52.
53.
《中国有色金属学会会刊》2022,32(12):4139-4155
Between the two major arsenic-containing salts in natural water, arsenite (As(III)) is far more harmful to human and the environment than arsenate (As(V)) due to its high toxicity and transportability. Therefore, preoxidation of As(III) to As(V) is considered to be an effective means to reduce the toxicity of arsenic and to promote the removal efficiency of arsenic. Due to their high catalytic activity and arsenic affinity, iron-based functional materials can quickly oxidize As(III) to As(V) in heterogeneous Fenton-like systems, and then remove As(V) from water through adsorption and surface coprecipitation. In this review, the effects of different iron-based functional materials such as zero-valent iron and iron (hydroxy) oxides on arsenic removal are compared, and the catalytic oxidation mechanism of As(III) in heterogeneous Fenton process is further clarified. Finally, the main challenges and opportunities faced by iron-based As(III) oxidation functional materials are prospected. 相似文献
54.
55.
56.
57.
Qing Wang Liang Yu Hiroki Nagasawa Masakoto Kanezashi Toshinori Tsuru 《Journal of the American Ceramic Society》2020,103(8):4473-4488
Polytitanocarbosilane (TiPCS)-derived ceramic membranes were fabricated using a pre-ceramic polymer. Special attention was focused on a process of thermal-oxidative curing that was used to induce cross-linking and the effect of this process on the ceramic yield, thermal stability, oxidation resistance, and microstructure of TiPCS. The cross-linked TiPCS powders showed a ceramic yield and thermal stability that were higher than that from the non-cross-linked version. In addition, the cross-linked TiPCS with uniform micropores showed higher levels of N2 and CO2 adsorption capacity, BET surface area, and micropore volume than the non-cross-linked versions, and the cross-linking process enhanced the stability of the pore structure at high temperature. The cross-linked TiPCS membranes showed high H2 permeance (1.49 × 10−6 mol/(m2 s Pa)) with sub-nanopores (H2/SF6 selectivity: 12 000, H2/N2: 10), and in addition higher oxidation resistance than their non-cross-linked counterparts. Furthermore, the influence of the concentration of the TiPCS precursor coating solution was optimized and the hydrothermal stability of the membranes at high temperatures was also evaluated. The optimized membrane demonstrated great performance for the pervaporation removal of methanol in binary azeotropic systems of either MeOH/butyl acetate or MeOH/toluene, and it also showed high hydrothermal stability with excellent dehumidification performance under high temperatures. 相似文献
58.
《Ceramics International》2020,46(5):6012-6021
In the study, we doped N into TiO2 lattice to narrow its band gap energy. Then, the synthesized N doped TiO2 material was combined with AgI to form AgI/N–TiO2 (ANT) direct Z scheme materials. The synthesized materials were utilized for photocatalytic removal of tetracycline (TC) using visible irradiation as an excitation source. We also conducted radical scavenging experiments to determine photocatalytic degradation mechanism. We investigated that these photo-excited electrons (e−) in N–TiO2 conduction band tended to combine with the left holes (h+) in AgI valence band maintaining h+ in the valence band of the N–TiO2 and e− in the conduction band of the AgI. The remained e− and h+ have high redox potential to initiate for photocatalytic decomposition of TC. Thus, the TC degradation by the ANT materials were significant greater than those by single components (AgI or N–TiO2). We also investigated that the TC degradation by the ANT-30 material, which the AgI: N–TiO2 molar ratio was 30%, exhibited that highest degradation efficiency. Finally, the ANT photocatalyst exhibited excellent stability during TC degradation processes supporting for its promising potential application in practical systems. 相似文献
59.
60.
Wenjie Wang Xiaoxia Hu Lingyu Li Wei Jing Anran Guo Haiyan Du 《Ceramics International》2019,45(6):6723-6729
Here, we developed silica/mullite fiber composite membranes with double-layer structure by a simple vacuum procedure for the removal of sub-micrometer dust. The support with three-dimensional skeleton structure exhibited high porosity (higher than 90%), low density (lower than 0.25?g/cm3) and high compressive strength (higher than 0.55?MPa) at 1000?°C. By controlling the mass ratio of silica sol to mullite fiber, we can obtain uniform and complete filtering layers with different thicknesses. The composite membranes exhibited high PM filtration efficiency with 99% for 1–10?µm, 97% for 0.5?µm and 90% for 0.3?µm. These samples had high air flow with very low pressure drop (lower than 600?Pa when airflow velocity reached 1?m/s). These results indicated that the silica/mullite fiber composite membranes were very promising for PM pollution control in the field of hot gas filtration. 相似文献