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1.
Developing efficient, stable and ideal urea oxide (UOR) electrocatalyst is key to produce green hydrogen in an economical way. Herein, Ru doped three dimensional (3D) porous Ni3N spheres, with tannic acid (TA) and urea as the carbon and nitrogen resources, is synthesized via hydrothermal and low-temperature treated process (Ru–Ni3N@NC). The porous nanostructure of Ni3N and the nickel foam provide abundant active sites and channel during catalytic process. Moreover, Ru doping and rich defects favor to boost the reaction kinetics by optimizing the adsorption/desorption or dissociation of intermediates and reactants. The above advantages enable Ru–Ni3N@NC to have good bifunctional catalytic performance in alkaline media. Only 43 and 270 mV overpotentials are required for hydrogen evolution (HER) and oxygen evolution (OER) reactions to drive a current of 10 mA cm?2. Moreover, it also showed good electrocatalytic performance in neutral and alkaline seawater electrolytes for HER with 134 mV to drive 10 mA cm?2 and 83 mV to drive 100 mA cm?2, respectively. Remarkably, the as-designed Ru–Ni3N@NC also owns extraordinary catalytic activity and stability toward UOR. Moreover, using the synthesized Ru–Ni3N@NC nanomaterial as the anode and cathode of urea assisted water decomposition, a small potential of 1.41 V was required to reach 10 mA cm?2. It can also be powered by sustainable energy sources such as wind, solar and thermal energies. In order to make better use of the earth's abundant resources, this work provides a new way to develop multi-functional green electrocatalysts.  相似文献   
2.
非变性条件下的蛋白质研究可以提供更准确的高级结构信息,为“序列-结构-功能”关系解析提供更接近生理条件的分子基础。非变性质谱(native MS)是在非变性条件下对目标蛋白质进行质谱分析的技术。近年来,非变性质谱在蛋白构象、蛋白质非共价相互作用以及蛋白质组装复合物等高阶结构解析中发挥着不可替代的作用,并逐渐成为结构生物学研究的重要支撑方法之一。本文总结了非变性结构质谱在蛋白提取、离子源开发与构象解析方面的发展现状,并提出了非变性结构质谱领域现阶段的技术瓶颈与潜在的解决策略,主要包含原位分析能力和结构分辨率的提升这两方面。  相似文献   
3.
Jingdezhen is famous for its bluish white (Qingbai) porcelains of the Song Dynasty, and those decorated with iron spots are distinctive among them. Herein, iron spots on a bluish white porcelain were investigated using a series of microscopic and spectroscopic characterizations. We found the decreasing iron content from more than 8 wt% to about 2 wt% during the glaze color transition from rusty to brown and finally into green, which built a connection on the coloring mechanism of iron-rich crystallized glaze and celadon glaze. We identified the rare ε-Fe2O3, a promising magnetic material, in both the dark brown crystals and the triangular crystals in the rusty area, which is its first discovery among bluish white porcelains. Based on these findings, we discussed the coloring mechanism of iron-spot decoration along with the physical form of the iron oxide crystals, indicating the partially reducing atmosphere during firing process.  相似文献   
4.
《Ceramics International》2022,48(11):15422-15429
Hydrothermal method is widely used in the synthesis of perovskite-type oxides, whereas few studies are reported for the nucleation mechanism, so that the relationship between the crystal structures and reactive activities of reactants and products is still unknown. Herein, the reaction processes are analyzed on the basis of XRD, SEM and Raman characterizations, and the nucleation mechanism is investigated for the hydrothermal synthesis of MZrO3 (M = Ba, Sr, Ca). We propose that the negative charged cyclic tetramer complexes [Zr4(OH)8(OH)16]8- form in the hydrothermal reaction, which play major roles in the nucleation process. The tetramer complexes continually dehydrate and condensate to form substructural units composed of alkali-earth ions and 6-fold Zr tetramers; substructural units further dehydrate and distort to form perovskite structures. The reactive activation energy increases with the decreasing of M2+ (M = Ba, Sr, Ca) ionic radius because the incorporation of smaller A site ions in the perovskite structure is accompanied by greater rotation and distortion of the ZrO6 octahedra, leading to the decrease of reactive activity accordingly. In a word, the proposed nucleation mechanism in this paper is of great significance for the study of perovskite.  相似文献   
5.
傅里叶变换-离子回旋共振质谱(FT-ICR MS)具有较高的分辨率和串联质谱分析能力。离子在分析池中做回旋运动时,镜像电流会因离子与中性分子发生碰撞而逐渐衰减。基于此,通过选择合适的理论模型,并结合相应的算法,可推算出离子的碰撞截面(CCS)。该方法无需增加仪器硬件成本,可通过直接分析高分辨质谱数据获取离子结构信息。近年来,随着FT ICR MS仪器的发展和推广,该方法得到快速发展。本文综述了此类方法使用的碰撞模型、利用时域和频域信号进行数据分析的不同方法及特点,虽然提供的离子CCS数据的可靠性和准确度有待进一步提高,但在离子的动态CCS测量以及离子异构化的研究中表现出独特优势。该方法可进一步与离子淌度技术相结合,借助FT ICR MS较高的质量分辨能力和离子操控能力,提供多维度的离子结构信息。  相似文献   
6.
研究了一种聚乙烯醇(PVA)和胶原(COL)复合支架材料的制备方法。采用氨基硅烷对PVA海绵表面进行了氨基化修饰后,通过戊二醛溶液交联牛Ⅰ型胶原(COL),最后通过赖氨酸溶液封闭,获得一种PVA/COL复合支架材料。采用扫描电镜(SEM)、X光电子能谱仪(XPS)、傅里叶红外光谱(FT-IR)等手段对支架材料的理化性能进行表征,并通过细胞实验对支架材料的生物学性能进行评价。结果表明,经过COL修饰的PVA孔隙率为21.33%,平均孔径为168.68 ?m且均匀分布,支架材料接触角为20.03°。对支架材料的生物学评价结果表明C3A细胞在复合材料上黏附良好,优于PVA组;CCK-8增殖检测结果表明细胞在复合材料上呈增殖生长趋势,与对照组PVA相比差异显著(P?0.01)。将PVA和COL复合制备得到的支架材料具有良好的理化及生物学特性,具有广阔的应用前景。  相似文献   
7.
Zuo  Xintao  Zhen  Mengmeng  Wang  Cheng 《Nano Research》2019,12(4):829-836

Lithium-sulfur batteries (LSBs) have been regarded as one of the most promising energy storage systems to break through the upper limit of lithium-ion batteries. However, the rampant diffusions of soluble lithium polysulfides (LiPSs) in the electrolyte induced the shuttle effect between anode and cathode, resulting in low sulfur utilization, low energy efficiency and short cycling life. Herein, we prove the rational design and construction of Ni nanoparticles filled in vertically grown N-doped bamboo-like carbon nanotubes (CNTs) on graphene nanosheets (Ni@NG-CNTs) as efficient polysulfide barrier for high-performance LSBs. The unique design integrates graphene nanosheets and CNTs into hierarchical architectures with one-dimensional (1D) CNTs, two-dimensional (2D) ultrathin nanosheets and abundant carbon nanocages. This design provides large surface area for lithium polysulfides (LiPSs) adsorption, accelerates electron transport and enhances electrochemical redox of LiPSs. Benefiting from the unique structural features, the LSBs with the Ni@NG-CNTs as polysulfide barrier keep high reversible specific capacities of 309.1 and 265.0 mAh·g−1 at 5 and 10 C rates after 500 cycles. This work provides a new strategy for constructing self-assembled hybrids of CNTs and graphene nanosheets with abundant carbon nanocages for high-performance LSBs.

  相似文献   
8.
9.
Unstable and low-abundance protein complexes represent a large family of transient protein complexes that are difficult to characterize, even by means of high-resolution NMR spectroscopy. A method to assign the NMR signals of these unstable complexes through a combination of selective isotope labeling of amino acids in a protein and site-specific labeling the protein with a paramagnetic tag is presented herein. By using this method, the resonances of unstable thioester intermediate complex (lifetime <5 h and highest concentration ≈20 μm ) generated by Staphylococcus aureus sortase A and its peptide substrate under a real-time reaction have been assigned.  相似文献   
10.
Doping with the additives in metal-N–H system has been regarded as one of the most effective approaches to improve its hydrogen storage properties. Herein, we prepared super activated carbon (SuperC) through the activation of commercial activated carbon by KOH and evaluated its effect on dehydrogenation properties of 2LiNH2MgH2. Our studies show that doping with SuperC could effectively lower its dehydrogenation temperatures. For instance, 2LiNH2MgH2–10 wt% SuperC can release 4.86 wt% of hydrogen upon heating up to 300 °C with the onset and peak dehydrogenation temperatures of 71 °C and 168 °C, respectively. Moreover, the release of byproduct NH3 was successfully suppressed. Measurement of thermal diffusivity suggests that the enhanced dehydrogenation properties may be ascribed to the improved heat transfer for solid-solid reaction resulting from doping with SuperC.  相似文献   
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