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71.
Traditional methods based on the product of exponentials (POE) formula are parametrically continuous and complete for the calibration of the kinematic parameters of serial robots. However, these methods are not minimal due to the constraints of joint twists. This paper puts forward a new POE-based model, whose parameters are totally independent and conform to the formula of minimality. This is the first model that simultaneously satisfies the requirements of parametric continuity, completeness, and minimality with uniform and generic modeling rules. The proposed approach avoids the operations of normalization and orthogonalization which are necessary redundancy elimination steps with the traditional model. Simulations on a SCARA robot and experiments on an ABB IRB 120 robot prove that the new model outperforms in convergence, accuracy, and efficiency. 相似文献
72.
73.
生物质中元素分布特征的聚类分析研究 总被引:2,自引:0,他引:2
测定了稻草秆、小麦秆、玉米秆、棉花秆、大豆秆、玉米芯、花生壳和柳树、松树、桦树、杨树、杉树 1 2个农业生物质和林业生物质种类 2 7个样品中主要元素 K,Ca,Na,Mg,Al,Fe,P和痕量元素 As,Cr,Co,Cu,Cd,Mn,Mo,Ni,Pb,Ti,Zn,V,Si,Ba,Be,Se,Sb,Ge,Hg的含量 ,并用SPSS聚类分析法分别进行了 R型和 Q型聚类研究 ,对这些元素在生物质中的分布特征进行了研究 .结果显示 :杨木、杉木和桦木与松木和柳木归成一大类 ,经济类作物黄豆秆和棉花秆分别归类后又归入一大类 ;农业生物质稻草秆和小麦秆、玉米秆被归入一类 ;虽然 2 7种生物质样品分别取自我国东北、华东、华北和西南地区 ,在地理位置上相距极远 ,但样品聚类谱系图表明 ,元素的分布特征与生物质的种类的关系显著 ,与产地的关系不明显 ,即元素的分布特征受种类的影响大 ,而受生长环境、气候、土壤条件的影响小 . 相似文献
74.
A novel treatment process combining a membrane with outside-in flow configuration and a fluidized pellet rector for removing hardness was studied. The effects of influent water quality, e.g., concentrations of natural organic matter (NOM) and phosphate along with the hydrophobicity of NOM, on the hardness removal efficiency of the novel process were investigated. The hardness removal efficiency decreases with increasing NOM concentration. However, the NOM removal efficiency is independent of NOM concentration and is related to the hydrophobicity of NOM samples. Raw water containing phosphate has adverse impact on the hardness removal efficiency, which decreases from 85% for treating water containing no phosphate to only 38% and 14% for water containing 0.33 mg/L and 1.63 mg/L of phosphate, respectively. 相似文献
75.
76.
An ionic liquid, 1-butyl-3-methylimidazolium bromide, is used as reaction medium for the synthesis and crystallization of a coordination polymer, (BMIM)2[Cd3(BDC)3Br 2] (1) (BMIM = 1-butyl-3-methylimidazolium, BDC = 1,4-benzenedicarboxylate), which forms an anionic two-dimensional framework with the imidazolium cations located between the layers. This compound is thermally stable up to ca. 340 °C and exhibits blue emission in solid state at room temperature. Other characterizations by IR and UV–visible spectra are also described. 相似文献
77.
End amino, carboxylic acid, and hydroxyl functionalized styrene–butadiene–styrene (SBS) triblock copolymers were prepared with 1,5‐diazabicyclo[3.1.0]hexane, carbon dioxide, and epoxy ethane as capping agents, respectively. The effects of the end polar groups on the morphology and dynamic mechanical properties were investigated. Transmission electron microscopy images suggested that the group at the end of the polystyrene (PS) segment made the morphology of the PS domains disordered and incompact. Dynamic mechanical results showed that the storage and loss modulus increased after SBS was end‐functionalized. End amino and carboxylic acid groups improved the compatibility and storage stability of SBS‐modified asphalt. However, the effect of the end‐hydroxyl group on the improvement of the storage stability of SBS‐modified asphalt was not obvious. The differential scanning calorimetry analysis of SBS‐modified asphalt further showed that the compatibility and storage stability of SBS‐modified asphalt were improved by the attachment of amino or carboxylic acid groups through the anionic polymerization method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 8–16, 2007 相似文献
78.
79.
Two series of siloxane-urethane copolymers were prepared from polydimethylsiloxane (PDMS) with a molecular weight of 1000 or 1800 which was used as a soft segment, 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (1,4-BD). Differential scanning calorimetry (DSC) demonstrated that the position (Tgs) and breadth (ΔB) of soft-segment glass transition of copolymers remained constant as the hard-segment content increased. Heat capacities at soft-segment glass transition of the copolymer (ΔCp) were 0.195∼0.411 J/g○C and heat capacities of pure PDMS (ΔCp0) were 0.571∼0.647 J/g○C, leading to the various ΔCp/ΔCp0 ratios. The ΔCp/ΔCp0 ratios decreased as the increasing of hard-segment content, showing poor phase separation. The FTIR spectrum confirmed the occurrence of hydrogen bonding in ether end-group of pure PDMS. The ether group of the soft segment led to interfacial mixing between soft and hard segments. The tan δ of the soft segment determined by dynamic mechanical testing (DMA) also identified the mixing of soft and hard segments. The mechanical properties of the copolymer were directly related to either the soft and hard segment contents or the chain lengths of soft and hard segments. The hard segment that reinforced the soft segment and interfacial thickness between soft and hard segment dominated the mechanical properties. 相似文献
80.
Stephen Q. Zhou Liming Wang Xiugao Liao Georges Manuel William P. Weber 《Journal of Inorganic and Organometallic Polymers and Materials》1991,1(2):199-210
High molecular weight poly(1,1-dimethyl-1-germa-cis-pent-3-ene), poly(1,1-diphenyl-1-germa-cis-pent-3-ene), poly(1,1-dimethyl-1-sila-cis-pent-3-ene), and poly(1-methyl-1-phenyl-1-sila-cis-pent-3-ene) have been prepared. The thermal stability of these polymers is found to increase with their molecular weight. 相似文献