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排序方式: 共有575条查询结果,搜索用时 15 毫秒
1.
准确测定辛酸铑催化剂中杂质元素含量,是判定产品是否合格的重要指标之一。以往常采用直流电弧发射光谱法(摄谱法)进行检测,但测定周期长,且重复性较差。用电感耦合等离子体原子发射光谱法(ICP-AES)测定辛酸铑催化剂中微量杂质元素时,辛酸铑催化剂样品中含有的大量有机组分和铑基体会对测定有严重干扰。实验采用反复滴加硝酸消解样品中有机组分,再用王水溶解盐类,选用合适背景点扣除的方式消除铑基体的干扰,建立了使用ICP-AES测定辛酸铑催化剂中0.001%~0.1%(质量分数)Pt、Pd、Pb、Fe、Cu、Al、Ni等7种微量杂质元素的方法。各元素在0.10~10.00μg/mL范围内与其发射强度呈线性关系,相关系数均大于0.9999;方法检出限(μg/mL)为0.075(Pt)、0.0033(Pd)、0.015(Pb)、0.0036(Fe)、0.010(Cu)、0.001(Al)、0.012(Ni)。实验方法用于测定辛酸铑催化剂样品中Pt、Pd、Pb、Fe、Cu、Al、Ni,结果的相对标准偏差为(RSD,n=7)为1.4%~9.6%。按照实验方法测定辛酸铑催化剂中Pt、Pd、Pb、Fe、Cu、Al、Ni,并与直流电弧发射光谱法的测定结果进行比对,结果相一致。 相似文献
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Boram Seo Woo Hyung Jeon Chul‐Eui Kim Sanghyuck Kim Sung Hong Kim Phil Ho Lee 《Advanced Synthesis \u0026amp; Catalysis》2016,358(7):1078-1087
Sequential copper‐catalyzed [3+2] cycloaddition, rhodium‐catalyzed O H insertion, intramolecular 1,8‐addition, and rearrangement starting from 1‐alkynes, N‐sulfonyl azides, and tropolones is demonstrated for the synthesis of the 2‐functionalized aminotropones in one pot. These results indicate that sequential functionalization of O H and C(sp2) O bonds smoothly occurs in the C(sp2) O H bonds of tropolone
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Chengyong Yang Bolong Huang Shuxing Bai Yonggang Feng Qi Shao Xiaoqing Huang 《Advanced materials (Deerfield Beach, Fla.)》2020,32(24):2001267
Electrocatalytic nitrogen reduction reaction (NRR) is a promising process relative to energy-intensive Haber–Bosch process. While conventional electrocatalysts underperform with sluggish paths, achieving dissociation of N2 brings the key challenge for enhancing NRR. This study proposes an effective surface chalcogenation strategy to improve the NRR performance of pristine metal nanocrystals (NCs). Surprisingly, the NH3 yield and Faraday efficiency (FE) (175.6 ± 23.6 mg h–1 g–1Rh and 13.3 ± 0.4%) of Rh-Se NCs is significantly enhanced by 16 and 15 times, respectively. Detailed investigations show that the superior activity and high FE are attributed to the effect of surface chalcogenation, which not only can decrease the apparent activation energy, but also inhibit the occurrence of the hydrogen evolution reaction (HER) process. Theoretical calculations reveal that the strong interface strain effect within core@shell system induces a critical redox inversion, resulting in a rather low valence state of Rh and Se surface sites. Such strong correlation indicates an efficient electron-transfer minimizing NRR barrier. Significantly, the surface chalcogenation strategy is general, which can extend to create other NRR metal electrocatalysts with enhanced performance. This strategy open a new avenue for future NH3 production for breakthrough in the bottleneck of NRR. 相似文献
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铑催化线性氢甲酰化反应的研究进展 总被引:1,自引:0,他引:1
《石油化工》2015,44(10):1149
介绍了氢甲酰化反应机理;综述了线性氢甲酰化配体的发展过程,包括双齿膦配体、三齿膦配体及四齿膦配体,双齿膦配体中重点介绍了Bisbi系列配体、Xantphos系列配体和具有大位阻的含亚磷酸酯键的Biphephos系列配体的结构及应用;并从配体的设计出发,简要地介绍了氢甲酰化的机理和影响线性氢甲酰化反应选择性的因素。对如何推动我国线性氢甲酰化工业的发展提出了展望。 相似文献
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《International Journal of Hydrogen Energy》2021,46(63):32017-32035
A comprehensive study was conducted on the performance of M-promoted (M = 1%Ru, 1%Rh, 5%Ni) upgraded slag oxide metallurgical waste catalysts (M-UGSO) for hydrogen production by glycerol steam reforming (GSR). The results confirmed that the tendency of the incorporated metal to interact with Mg/Fe containing species within UGSO plays a key role in the surface availability of the corresponding metal, structural changes after reduction, and catalyst stability. Aside its best stability, 5% Ni-UGSO showed a performance (glycerol conversion to gaseous products of 100% and H2 yield of 74%) comparable with 1% Rh-UGSO (100% and 78%, respectively) or even surpassing that of 1% Ru-UGSO (94% and 71%, respectively), as noble metal-based catalysts. Synergistic cooperation was achieved by incorporated metals (M) and Fe/Mg containing species within UGSO, resulting in enhanced glycerol and water activation. The weakest results of Ru-UGSO could be justified by lack of propensity for MgO–RuO2 interaction on UGSO surface. 相似文献
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Shunsuke Kato Prof. Akira Onoda Naomasa Taniguchi Prof. Ulrich Schwaneberg Prof. Takashi Hayashi 《Chembiochem : a European journal of chemical biology》2021,22(4):679-685
Directed evolution of Cp*RhIII-linked nitrobindin (NB), a biohybrid catalyst, was performed based on an in vitro screening approach. A key aspect of this effort was the establishment of a high-throughput screening (HTS) platform that involves an affinity purification step employing a starch-agarose resin for a maltose binding protein (MBP) tag. The HTS platform enables efficient preparation of the purified MBP-tagged biohybrid catalysts in a 96-well format and eliminates background influence of the host E. coli cells. Three rounds of directed evolution and screening of more than 4000 clones yielded a Cp*RhIII-linked NB(T98H/L100K/K127E) variant with a 4.9-fold enhanced activity for the cycloaddition of acetophenone oximes with alkynes. It is confirmed that this HTS platform for directed evolution provides an efficient strategy for generating highly active biohybrid catalysts incorporating a synthetic metal cofactor. 相似文献