全文获取类型
收费全文 | 112258篇 |
免费 | 10129篇 |
国内免费 | 6106篇 |
专业分类
电工技术 | 2240篇 |
技术理论 | 5篇 |
综合类 | 7466篇 |
化学工业 | 14163篇 |
金属工艺 | 21681篇 |
机械仪表 | 4420篇 |
建筑科学 | 18802篇 |
矿业工程 | 2666篇 |
能源动力 | 2604篇 |
轻工业 | 3003篇 |
水利工程 | 1185篇 |
石油天然气 | 2358篇 |
武器工业 | 857篇 |
无线电 | 4603篇 |
一般工业技术 | 20909篇 |
冶金工业 | 19349篇 |
原子能技术 | 799篇 |
自动化技术 | 1383篇 |
出版年
2024年 | 380篇 |
2023年 | 1689篇 |
2022年 | 2972篇 |
2021年 | 3623篇 |
2020年 | 3933篇 |
2019年 | 3093篇 |
2018年 | 2776篇 |
2017年 | 3805篇 |
2016年 | 3844篇 |
2015年 | 4151篇 |
2014年 | 6838篇 |
2013年 | 6312篇 |
2012年 | 7786篇 |
2011年 | 9315篇 |
2010年 | 6885篇 |
2009年 | 7241篇 |
2008年 | 6006篇 |
2007年 | 7463篇 |
2006年 | 6633篇 |
2005年 | 5752篇 |
2004年 | 4721篇 |
2003年 | 4074篇 |
2002年 | 3454篇 |
2001年 | 2814篇 |
2000年 | 2456篇 |
1999年 | 1919篇 |
1998年 | 1586篇 |
1997年 | 1374篇 |
1996年 | 1160篇 |
1995年 | 886篇 |
1994年 | 825篇 |
1993年 | 570篇 |
1992年 | 499篇 |
1991年 | 381篇 |
1990年 | 336篇 |
1989年 | 280篇 |
1988年 | 163篇 |
1987年 | 98篇 |
1986年 | 69篇 |
1985年 | 55篇 |
1984年 | 57篇 |
1983年 | 39篇 |
1982年 | 51篇 |
1981年 | 24篇 |
1980年 | 51篇 |
1979年 | 8篇 |
1975年 | 6篇 |
1959年 | 11篇 |
1955年 | 5篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
对唐钢薄板坯连铸机生产的SS400钢的生产工艺进行了分析,认为薄板坯连铸机生产的SS400钢,在采取了精炼站在线定氧,将钢水全氧控制在25×10~(-6)左右,同时连铸采取保护浇注和轻压下等技术后,能够确保薄板坯连铸SS400钢的顺利浇注,轧制的板带材表面质量良好,机械性能符合要求。 相似文献
63.
Effect of Rare Earth Element Cerium on Mechanical Properties and Morphology of TiN Coating Prepared by Arc Ion Plating 总被引:7,自引:0,他引:7
TiN coatings were deposited on polished substrates of W18Cr4V high speed steel by means of vacuum arc ion plating. The effect of cerium on adhesion between TiN coating and substrate was studied. The microstructures and composition of TiN coatings were also investigated by means of scanning electron microscope (SEM), Auger electron spectroscopy (AES), and X-ray diffraction (XRD) technique. It was found that cerium is an effective modifying agent and the addition of suitable amount of cerium to TiN coatings can produce relatively excellent properties such as micro-hardness, wear resistance, oxidation resistance and porosity. The experimental results show that the added cerium in TiN coatings makesa contribution to form the preferred direction along with a (111 ) or (222) close packed face, which may be one of the reasons that improves some properties mentioned above. 相似文献
64.
U. Schmidhammer V. DeWaele S. Mintova E. Riedle T. Bein 《Advanced functional materials》2005,15(12):1973-1978
The ultrafast deprotonation of 2‐(2′‐hydroxyphenyl)benzothiazole (HBT) hosted in nanometer‐sized FAU and MFI zeolites is reported. Samples are prepared via in‐situ incorporation of HBT in the precursor colloidal solutions resulting in the formation of nanometer‐sized zeolites under hydrothermal treatment. The diameter of the zeolite particles formed in the crystalline suspensions is determined by dynamic light scattering and high‐resolution transmission microscopy to lie in the range 40–100 nm. It is shown that the HBT loading does not influence the degree of the zeolite crystallinity but does change the size and the morphology of the individual zeolite nanoparticles. Colloidal suspensions containing the crystalline nanoparticles are well suited for optical investigations since they are sufficiently transparent and clear. The photochemical properties of the HBT guest in the zeolite‐host systems are studied with femtosecond transient transmission spectroscopy. Depending on the acid–base properties either the enol or the keto tautomer of HBT is found to be hosted in the internal voids of the zeolites; upon UV excitation, the HBT‐keto tautomer is converted to the enol form in both MFI‐ and FAU‐type hosts. The HBT photoconversion takes place via an ultrafast deprotonation within 1.5 ps as detected by femtosecond transient absorption spectroscopy. 相似文献
65.
本文主要阐述了通过爆炸焊接和热轧的方法,研制成功可焊性良好的且具有较好强度、韧性与综合性能的双相耐应力腐蚀的不锈复合钢板。还将热轧与热处理的两种试验作了较全面的常规、特殊检验试验,结果完全达到使用要求。 相似文献
66.
R. Knockaert I. Doghri Y. Marchal T. Pardoen F. Delannay 《International Journal of Fracture》1996,81(4):383-399
Double-edge notched (DENT) steel plates were pulled until complete fracture and several experimental observations were made (using profilometry and scanning electron microscopy). The essential work of fracture (EWF) model was found to be well verified. Numerical simulations—up to the maximum load only—of some experiments were performed using the finite element method (FEM), and incorporating geometric and material non-linearities (large deformation elasto-plasticity). Some experimental measurements were compared with the corresponding numerical computations and excellent agreement was found. 相似文献
67.
WC对Cu/WC_P复合材料性能及组织的影响 总被引:8,自引:0,他引:8
通过WC含量对WC/Cu复合材料性能的影响,确定了冷压-烧结法制备Cu/WC材料的适宜WC含量为10vol%左右。并就WC对该材料组织和再结晶行为的影响进行了有益的探讨。 相似文献
68.
阐述了小电炉采用投资少,见较快,简单易行的炉外处理措施,提高了钢质量和生产率,生产实践和应用结果表明,本措施可为同类型企业的炼钢工艺完善和技术进步提供参考。 相似文献
69.
The mechanism of “475°C embrittlement” of a duplex stainless steel was investigated using finite element modelling of the stress distribution at brittle fracture initiation. Brittle fracture initiated at a critical shear stress, which increased with ferrite hardness. The fracture stress was affected by the duplex microstructure. Fracture was nucleated by deformation twins, which were identified using electron back-scatter diffraction. The ductile-to-brittle fracture transition was sensitive to age-hardening and could be described simply by the effect of age-hardening and test temperature on the yield stress. 相似文献
70.
We analyze specific features of the design of equipment used for mechanical testing of sheet structural materials under the conditions of biaxial static, cyclic, or dynamic loading. We propose original solutions of the problems related to the fatigue testing of crosslike specimens performed without using complex hydraulic systems and their dynamic testing carried out by using very simple testing machines for uniaxial tension–compression. 相似文献