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81.
采用重剪比以及配筋率两个试验变量对4个板柱中节点的破坏过程进行了对比试验,并在试验过程中采用特制应变测杆对试件内部斜裂缝的形成和发展予以监测。试验结果表明:试件最终破坏形态受重剪比和配筋率两因素共同影响;重剪比相同的试件,配筋率的提高也可有效提高中柱节点对不平衡弯矩的承载力;板内斜裂缝在节点发生冲切破坏之前已产生,并从靠近柱头的受压区向板底受拉区开展。基于试验结果和历史试验数据,将中国规范 GB 50010—2010所采用的基于偏心剪应力模型的计算方法和欧洲规范 Eurocode2-04进行对比,分析了偏心剪应力模型不足的原因。 相似文献
82.
Epoxy/kaolinite nanocomposites were prepared by adding the organically modified layered kaolinite to an epoxy resin [biphenyl phenol novolac epoxy resin (BPNE)] with 4,4′‐diamino biphenyl sulfone (DDS) as a curing agent. The dispersion state of the kaolinite within crosslinked epoxy‐resin matrix was examined by X‐ray diffraction (XRD) and transmission electron micrograph (TEM). The effects of kaolinite on thermal properties were investigated and discussed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Experimental results show that BPNE/kaolinite nanocomposites exhibit improved thermal than pure BPNE. When the kaolinite content is 5 wt %, the BPNE/kaolinite nanocomposites show the best thermal properties. These results indicate that nanocomposition is an efficient and convenient method to improve the thermal properties of BPNE. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
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A novel benzoxazine containing maleimide and carboxylic moieties, 1‐[3‐(4‐carboxylphenyl)‐3,4‐dihydro‐2H‐benzo[e][1,3]‐oxazin‐6‐yl]maleimide (Mal‐Bz‐Co), was synthesized and the structure was identified by 1H‐NMR and FTIR. Mal‐Bz‐Co exhibited good solubility in common organic solvents. The cure behavior of Mal‐Bz‐Co and cocure behavior of Mal‐Bz‐Co with o‐cresol formaldehyde epoxy resin were investigated by differential scanning calorimetry. Results indicated that Mal‐Bz‐Co showed a single curing exothermic peak at about 238.3°C. However, the maximum curing temperature (Tp) decreased to 146.1°C when Mal‐Bz‐Co cocured with o‐cresol formaldehyde epoxy resin in the molar ratio of 1 : 1. The Tp was about 92°C lower than that of Mal‐Bz‐Co. Thermogravimetric analysis showed that high‐decomposition temperature and char yield were observed for the cured resins of Mal‐Bz‐Co and Mal‐Bz‐Co/o‐CFER. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
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深部软弱围岩叠加拱承载体强度理论及应用研究 总被引:2,自引:0,他引:2
目前,长锚索与锚喷网支护相结合的支护方式在深部软弱围岩中已经得到了广泛应用,但是对于这种联合支护结构的承载特点缺乏深入了解,特别是对于初次支护和二次支护的承载能力没有量化解析式。因此,在岩石力学理论的基础上,针对深部软弱围岩的“锚喷网+锚索”联合支护特点,提出由主压缩拱(锚杆支护)和次压缩拱(密集型锚索支护)共同构成的叠加拱承载体力学模型;根据弹塑性理论、锚杆的中性点理论和锚索的力传递机制推导初次支护和适当让压后二次支护的承载体强度方程;并将“围岩–支护结构”组成的共同体看作一种等效耦合围岩,运用弹塑性力学方法得到这种等效耦合围岩的力学参数随释放位移(让压位移)变化的关系式。工程计算表明,金川III矿区破碎硐室经叠加拱支护后,极限承载能力 可达到513.34 kN,等效耦合岩体 值可达到47.54°, 最大值为1.37 MPa,提高围岩的峰后强度,有利于硐室围岩的长期稳定;现场监测也表明,进行叠加拱承载体支护后的硐室围岩变形趋于平稳,收敛速率小于0.1 mm/d。 相似文献
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Synthesis of dodecylbenzene via the alkylation of benzene and 1-dodecene over mesopore Beta zeolites
Baoyu Liu Weijian Lu Yikuan Liu Qilong Feng Yi Huang Jin Shang Yihan Zhu Jinxiang Dong 《American Institute of Chemical Engineers》2023,69(11):e18201
The alkylation of benzene with long chain α-olefins is a crucial process in the production of fine chemicals, which requires the upgrading from traditional homogeneous catalysis to heterogeneous catalysis involving zeolites. However, the application of zeolite catalysts has been limited by their fast deactivation due to constrained diffusion resulting from the sole micropores. To address this challenge, a desilication and secondary-crystallization strategy has been employed to fabricate hierarchically structured mesoporous Beta zeolites. The resultant mesoporous Beta zeolites demonstrate excellent catalytic activity and stability in the alkylation of benzene with 1-dodecene, arising from the exposed acid sites and enhanced internal diffusion. Importantly, the internal diffusion limitations for these mesopore Beta zeolites are negligible, which significantly extends their lifetime and improves their regeneration performance. To achieve these benefits, the degree of mesopores must be deliberately controlled. Overall, this approach provides a promising solution for achieving efficient and environmentally friendly alkylation processes. 相似文献
88.
Youqi Li Xiaopeng Chen Linlin Wang Xiaojie Wei Weijian Nong Xuejuan Wei Jiezhen Liang 《中国化学工程学报》2023,53(1):155-169
The vapor–liquid equilibrium(VLE) data of a-pinene + camphene + [abietic acid + palustric acid + neoabietic acid] and a-pinene + longifolene + [abietic acid + palustric acid + neoabietic acid] systems at 313.15 K,333.15 K and 358.15 K were measured by headspace gas chromatography(HSGC). These data was compared with the predictions value by conductor-like screening model for realistic solvation(COSMO-RS).Moreover, the calculated data of COSMO-RS and Non-Random Two-Liquids(NRTL) models showed good... 相似文献
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