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991.
992.
小湾水电站工程的挑战与思考 总被引:2,自引:0,他引:2
小湾水电站位于我国西南高山峡谷地区,地形地质条件复杂,坝高、库大,泄洪流量及功率大,技术难度高,在许多方面均超越了现行规程规范及以往的认知,极具挑战性。该工程复杂高边坡、拱坝及拱座、坝基岩体开挖卸荷松弛、混凝土骨料料源、拱坝混凝土温控及裂缝、物探检测与安全监测、引水发电系统及临时设施、"数值小湾"等方面积累的经验和教训,必将使我国的高拱坝建设迈上一个新台阶。 相似文献
993.
Arsenic removal by iron-modified activated carbon 总被引:6,自引:0,他引:6
Iron-impregnated activated carbons have been found to be very effective in arsenic removal. Oxyanionic arsenic species such as arsenate and arsenite adsorb at the iron oxyhydroxide surface by forming complexes with the surface sites. Our goal has been to load as much iron within the carbon pores as possible while also rendering as much of the iron to be available for sorbing arsenic. Surface oxidation of carbon by HNO3/H2SO4 or by HNO3/KMnO4 increased the amount of iron that could be loaded to 7.6-8.0%; arsenic stayed below 10 ppb until 12,000 bed volumes during rapid small-scale tests (RSSCTs) using Rutland, MA groundwater (40-60 ppb arsenic, and pH of 7.6-8.0). Boehm titrations showed that surface oxidation greatly increased the concentration of carboxylic and phenolic surface groups. Iron impregnation by precipitation or iron salt evaporation was also evaluated. Iron content was increased to 9-17% with internal iron-loading, and to 33.6% with both internal and external iron loading. These iron-tailored carbons reached 25,000-34,000 bed volumes to 10 ppb arsenic breakthrough during RSSCTs. With the 33.6% iron loading, some iron peeled off. 相似文献
994.
995.
The objective of this work was to elucidate the influence of shear rates on the properties of polyamide 6/multiwalled carbon nanotube (PA6/CNT) composites which was realized by adopting different types of processing methods that feature different orders of magnitude in shear rates, such as compression molding (CM, ~0 s−1), conventional injection molding (CIM, ~102 s−1) and microinjection molding (μIM, ~105 s−1). Electrical conductivity (σ) results indicated that the prevailing high shearing conditions in injection molding was unfavorable for the formation of intact filler network, thereby resulting in a much lower σ than CM counterparts. Moreover, the σ of PA6/CNT microparts was higher than that of CIM macroparts when the filler content was less than 5 wt%, otherwise the σ of CIM macroparts prevailed over that of μIM counterparts. A better filler distribution was observed when PA6/CNT composites were processed under higher shearing conditions, as corroborated by SEM. In addition, CNTs were preferentially aligned along flow direction and a higher degree of CNT orientation was expected with increasing shear rates, as confirmed by Raman spectral analysis. The tensile strength of injection molded PA6/CNT samples increased with increasing filler concentrations, and the more preferential orientation and better distribution of CNT were considered to be the contributing factors. The comparative study of the properties of PA6/CNT composites that processed using different methods was important for their practical applications in industrial sectors. 相似文献
996.
In this work, transient thermal response and ablation behavior of liquid silicone rubber composites containing fluxing/ceramic forming fillers were investigated under different heat flows using an oxyacetylene flame. The results indicated that the introduction of zinc borate (ZB) and aluminum oxide (Al2O3) effectively reduced the temperature at various depths of the samples, and they improved the thermal insulation properties and lowered pyrolysis rates. The above finding was attributed to the heat absorption arising from water release and melt filling as well as the vitrified reaction of solid melt due to the decomposition of ZB. Besides, the melting and exfoliation of Al2O3 and the formation of aluminum silicate (Al2SiO5) caused heat absorption effect. Additionally, the mass ablation rates and line ablation rates increased with rising heat flows coupling with a decrease of compressive strength of the char layers. In a nutshell, the effect of adding ZB/Al2O3 on the thermal insulation behavior of epoxy-modified vinyl silicone rubber (EMVSR) composites under different heat flows was elucidtaed. This work served as a reference for the design and preparation of flexible ablative materials for thermal protection applications. 相似文献
997.
探索以丹皮酚为前体催化合成一氯代查尔酮及其黄酮的工艺,开拓合成氯代查尔酮和黄酮的新途径。让丹皮酚和不同位次的一氯代苯甲醛通过克莱森-斯密特反应碱催化合成一氯代的查尔酮Ⅰ、Ⅱ和Ⅲ,进而对三种查尔酮分别进行碘催化关环合成出来了一氯代的黄酮Ⅳ、Ⅴ和Ⅵ,测试产物的1H NMR、13C NMR、135° DEPT、FTIR以及其紫外和荧光性能,氯代黄酮Ⅳ、Ⅴ、Ⅵ的收率分别为88.6%、87.7%、86.1%,在荧光峰(λex/λem)220/415 nm处荧光强度分别为400、500、600。合成查尔酮是关键步骤,以合成查尔酮Ⅰ为例,通过考察碱、温度、溶剂等单因素对查尔酮产率的影响,经响应面法优化其合成工艺条件:一氯代苯甲醛的用量3.6 mmol、丹皮酚3 mmol、乙醇15 mL、NaOH 0.239 g、70 ℃下回流10 h,查尔酮Ⅰ的收率高达93.7%,同样条件下,查尔酮Ⅱ、Ⅲ的收率为92.3%、92.1%。该文合成一氯代查尔酮及其黄酮的工序简单、绿色环保,可实现规模化批量生产。 相似文献
998.
Ximian Xiao Dr. Min Zhou Zihao Cong Jingcheng Zou Prof. Runhui Liu 《Chembiochem : a European journal of chemical biology》2023,24(3):e202200368
Peptide mimics, possessing excellent biocompatibility and protease stability, have attracted broad attention and research in the biomedical field. β-Peptides and β-peptoids, as two types of vital peptide mimics, have demonstrated great potential in the field of foldamers, antimicrobials and protein binding, etc. Currently, the main synthetic strategies for β-peptides and β-peptoids include solid-phase synthesis and polymerization. Among them, polymerization in one-pot can minimize the repeated separation and purification used in solid-phase synthesis, and has the advantages of high efficiency and low cost, and can synthesize β-peptides and β-peptoids with high molecular weight. This review summarizes the polymerization methods for β-peptides and β-peptoids. Moreover, future developments of the polymerization method for the synthesis of β-peptides and β-peptoids will be discussed. 相似文献
999.
Bowen Li Prof. Yan Huang Prof. Qianli Zou 《Chembiochem : a European journal of chemical biology》2023,24(9):e202300002
Liver fibrosis is a process of excessive accumulation of extracellular matrix caused by liver injury. Liver fibrosis can progress to cirrhosis or even liver cancer without proper intervention. Until now, no effective therapeutic drugs have been clinically approved for treating liver fibrosis. Hence, the development of safe and effective antifibrotic drugs is particularly important. As a representative biomaterial, peptides have been investigated as key components for constructing antifibrotic nanomaterials given their advantages of biological origination, synthetic availability, and good biocompatibility. Peptides serve as multifunctional motifs in antifibrotic nanomaterials, such as liver-targeting molecules, antifibrotic molecules, and self-assembling building blocks for the formation of the nanomaterials. In this review, we focus on peptide-based nanoarchitectonics for treating liver fibrosis, including nanomaterials modified with liver-targeting peptides, nanomaterials for the efficient delivery of antifibrotic peptides, and self-assembled peptide nanomaterials for the delivery of antifibrotic drugs. The design rules of these peptide-based nanomaterials are described. The antifibrotic mechanisms and effects of these peptide-based nanomaterials in treating liver fibrosis and related diseases are highlighted. The challenges and future perspectives of using peptide-based nanoarchitectonics for the treatment of liver fibrosis are discussed. These results are expected to accelerate the rational design and clinical translation of antifibrotic nanomaterials. 相似文献
1000.