全文获取类型
收费全文 | 12885篇 |
免费 | 678篇 |
国内免费 | 98篇 |
专业分类
电工技术 | 287篇 |
综合类 | 34篇 |
化学工业 | 2724篇 |
金属工艺 | 280篇 |
机械仪表 | 339篇 |
建筑科学 | 349篇 |
矿业工程 | 37篇 |
能源动力 | 790篇 |
轻工业 | 1213篇 |
水利工程 | 146篇 |
石油天然气 | 195篇 |
武器工业 | 4篇 |
无线电 | 1546篇 |
一般工业技术 | 2537篇 |
冶金工业 | 995篇 |
原子能技术 | 144篇 |
自动化技术 | 2041篇 |
出版年
2024年 | 38篇 |
2023年 | 284篇 |
2022年 | 672篇 |
2021年 | 928篇 |
2020年 | 611篇 |
2019年 | 651篇 |
2018年 | 771篇 |
2017年 | 588篇 |
2016年 | 634篇 |
2015年 | 400篇 |
2014年 | 564篇 |
2013年 | 992篇 |
2012年 | 643篇 |
2011年 | 723篇 |
2010年 | 471篇 |
2009年 | 394篇 |
2008年 | 375篇 |
2007年 | 342篇 |
2006年 | 286篇 |
2005年 | 233篇 |
2004年 | 185篇 |
2003年 | 179篇 |
2002年 | 179篇 |
2001年 | 113篇 |
2000年 | 112篇 |
1999年 | 139篇 |
1998年 | 277篇 |
1997年 | 235篇 |
1996年 | 167篇 |
1995年 | 150篇 |
1994年 | 112篇 |
1993年 | 106篇 |
1992年 | 76篇 |
1991年 | 66篇 |
1990年 | 62篇 |
1989年 | 76篇 |
1988年 | 70篇 |
1987年 | 57篇 |
1986年 | 60篇 |
1985年 | 70篇 |
1984年 | 74篇 |
1983年 | 69篇 |
1982年 | 38篇 |
1981年 | 34篇 |
1980年 | 39篇 |
1979年 | 31篇 |
1978年 | 34篇 |
1977年 | 37篇 |
1976年 | 53篇 |
1972年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
12.
13.
Mohamed A.El-Nemr Ibrahim M.A.Ismail Nabil M.Abdelmonem Ahmed El Nemr Safaa Ragab 《中国化学工程学报》2021,36(8):199-222
Watermelon peel residues were used to produce a new biochar by dehydration method. The new biochar has undergone two methods of chemical modification and the effect of this chemical modification on its ability to adsorb Cr(VI) ions from aqueous solution has been investigated. Three biochars, Melon-B, Melon-BO-NH_2 and Melon-BO-TETA, were made from watermelon peel via dehydration with 50% sulfuric acid to give Melon-B followed by oxidation with ozone and amination using ammonium hydroxide to give Melon-BO-NH_2 or Triethylenetetramine(TETA) to give Melon-BO-TETA. The prepared biochars were characterized by BET, BJH,SEM, FT-IR, TGA, DSC and EDAX analyses. The highest removal percentage of Cr(VI) ions was 69% for Melon-B,98% for Melon-BO-NH_2 and 99% for Melon-BO-TETA biochars of 100 mg·L~(-1) Cr(VI) ions initial concentration and 1.0 g·L~(-1) adsorbents dose. The unmodified biochar(Melon-B) and modified biochars(Melon-BO-NH_2 and Melon-BO-TETA) had maximum adsorption capacities(Qm) of 72.46, 123.46, and 333.33 mg·g~(-1), respectively.The amination of biochar reduced the pore size of modified biochar, whereas the surface area was enhanced.The obtained data of isotherm models were tested using different error function equations. The Freundlich,Tempkin and Langmuir isotherm models were best fitted to the experimental data of Melon-B, Melon-BO-NH_2 and Melon-BO-TETA, respectively. The adsorption rate was primarily controlled by pseudo-second–order rate model. Conclusively, the functional groups interactions are important for adsorption mechanisms and expected to control the adsorption process. The adsorption for the Melon-B, Melon-BO-NH_2 and Melon-BO-TETA could be explained for acid–base interaction and hydrogen bonding interaction. 相似文献
14.
Dr. Raysa Khan Tareque Dr. Storm Hassell-Hart Dr. Tobias Krojer Dr. Anthony Bradley Dr. Srikannathasan Velupillai Dr. Romain Talon Dr. Michael Fairhead Dr. Iain J. Day Kamlesh Bala Dr. Robert Felix Dr. Paul D. Kemmitt Prof. Paul Brennan Prof. Frank von Delft Dr. Laura Díaz Sáez Prof. Kilian Huber Prof. John Spencer 《ChemMedChem》2020,15(24):2513-2520
Combined photochemical arylation, “nuisance effect” (SNAr) reaction sequences have been employed in the design of small arrays for immediate deployment in medium-throughput X-ray protein–ligand structure determination. Reactions were deliberately allowed to run “out of control” in terms of selectivity; for example the ortho-arylation of 2-phenylpyridine gave five products resulting from mono- and bisarylations combined with SNAr processes. As a result, a number of crystallographic hits against NUDT7, a key peroxisomal CoA ester hydrolase, have been identified. 相似文献
15.
16.
17.
Synthesis of novel nonionic surfactants has attracted attention of synthetic chemists due to the issues of the currently used commercial surfactants. The synthesis of three biocompatible triazole-based nonionic surfactants is reported for nanovesicular drug loading. The surfactants were synthesized in a three-step reaction and characterized using 1HNMR and mass spectroscopy techniques. They were investigated for their critical micelle concentration (CMC) using a UV–Visible spectrophotometer. Their biocompatibility was investigated against cell culture and in blood. All the synthesized nonionic surfactants were further explored for their nanovesicular drug loading using clarithromycin as a model hydrophobic drug. Nonionic surfactants revealed lower CMC in 35–45 μM and were less hemolytic and cytotoxic. They were capable of self-assembling in nanosize niosomal vesicles encapsulating increased amounts of drug. The results suggest the synthesized nonionic surfactants as biocompatible nanotechnology-based drug-delivery vehicles. 相似文献
18.
This paper considers the state‐dependent interference relay channel (SIRC) in which one of the two users may operate as a secondary user and the relay has a noncausal access to the signals from both users. For discrete memoryless SIRC, we first establish the achievable rate region by carefully merging Han‐Kobayashi rate splitting encoding technique, superposition encoding, and Gelfand‐Pinsker encoding technique. Then, based on the achievable rate region that we derive, the capacity of the SIRC is established in many different scenarios including (a) the weak interference regime, (b) the strong interference regime, and (c) the very strong interference regime. This means that our capacity results contain all available known results in the literature. Next, the achievable rate region and the associated capacity results are also evaluated in the case of additive Gaussian noise. Additionally, many numerical examples are investigated to show the value of our theoretical derivations. 相似文献
19.
Khalid Tauqeer Khan Abdul Nasir Ali Mazhar Adeel Adil ur Rehman Khan Atta Shuja Junaid 《Multimedia Tools and Applications》2019,78(17):24595-24615
Multimedia Tools and Applications - The world is facing many problems including that of traffic congestion. To highlight the issue of traffic congestion worldwide specially in urban areas and to... 相似文献
20.