全文获取类型
收费全文 | 76387篇 |
免费 | 6003篇 |
国内免费 | 3745篇 |
专业分类
电工技术 | 1523篇 |
技术理论 | 5篇 |
综合类 | 5736篇 |
化学工业 | 4107篇 |
金属工艺 | 19762篇 |
机械仪表 | 3788篇 |
建筑科学 | 16848篇 |
矿业工程 | 1550篇 |
能源动力 | 1414篇 |
轻工业 | 2163篇 |
水利工程 | 972篇 |
石油天然气 | 2381篇 |
武器工业 | 436篇 |
无线电 | 624篇 |
一般工业技术 | 7917篇 |
冶金工业 | 15594篇 |
原子能技术 | 562篇 |
自动化技术 | 753篇 |
出版年
2024年 | 207篇 |
2023年 | 853篇 |
2022年 | 2003篇 |
2021年 | 2206篇 |
2020年 | 2386篇 |
2019年 | 1770篇 |
2018年 | 1491篇 |
2017年 | 2370篇 |
2016年 | 2456篇 |
2015年 | 2780篇 |
2014年 | 4861篇 |
2013年 | 4252篇 |
2012年 | 5537篇 |
2011年 | 6319篇 |
2010年 | 4794篇 |
2009年 | 4983篇 |
2008年 | 3942篇 |
2007年 | 5153篇 |
2006年 | 4584篇 |
2005年 | 3798篇 |
2004年 | 3149篇 |
2003年 | 2759篇 |
2002年 | 2376篇 |
2001年 | 1994篇 |
2000年 | 1711篇 |
1999年 | 1384篇 |
1998年 | 1068篇 |
1997年 | 1039篇 |
1996年 | 894篇 |
1995年 | 635篇 |
1994年 | 583篇 |
1993年 | 399篇 |
1992年 | 350篇 |
1991年 | 253篇 |
1990年 | 209篇 |
1989年 | 169篇 |
1988年 | 117篇 |
1987年 | 59篇 |
1986年 | 42篇 |
1985年 | 31篇 |
1984年 | 27篇 |
1983年 | 27篇 |
1982年 | 26篇 |
1981年 | 18篇 |
1980年 | 41篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1975年 | 3篇 |
1959年 | 11篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
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
72.
StudyonHotDeformationCracksofSteelD2UsingProcesingMapGaoShan,LiuXianghua,WangGuodongABSTRACTThehotdeformationbehaviorsofsteel... 相似文献
73.
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
74.
75.
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
76.
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
77.
冷成型模具低温锌系磷化 总被引:4,自引:1,他引:3
研制出适用于冷成型模具高硬度表面的低温锌系磷化工艺。其中磷化液含Zn(H2 PO4 ) 2 ·2H2 O 6 0g/L ,Zn(NO3) 2 ·6H2 O 90g/L ,NaNO2 1.5g/L ,稀土促进剂 0~ 1.0g/L ,游离酸度 4~ 6点 ,总酸度 70~ 75点。该磷化液在 4 0℃下 ,处理 30~ 4 0min后可获得厚约 10 μm的磷化膜。性能测试表明 ,其减摩、润滑性能良好 ,摩擦系数约降 0 .1,与未处理试样相比磨损量下降 96 % ,附着力 1级。 相似文献
78.
K. P. Balan 《Journal of Failure Analysis and Prevention》2002,2(3):71-74
Wire ropes, pulleys, counterweights, and connecting systems are used for auto tensioning of contact wires of electric railways.
A wire rope in one such auto tensioning system suffered premature failure. Failure investigation revealed fatigue cracks initiating
at nonmetallic inclusions near the surface of individual wire strands in the rope. The inclusions were identified as Al-Ca-Ti
silicates in a large number of stringers, and some oxide and nitride inclusions were also found. The wire used in the rope
did not conform to the composition specified for AISI 316 grade steel, nor did it satisfy the minimum tensile strength requirements.
Failure of the wire rope was found to be due to fatigue; however, the ultimate fracture of the rope was the result of overload
that occurred after fatigue failure had reduced the number of wire strands supporting the load. 相似文献
79.
广州中城广场工程结构形式复杂,平面曲折多角。施工中在应用多种模板体系、泵送混凝土、无粘结预应力楼板及核心筒部分小平台滑模等方面,采用了多项新技术,保证了工程质量,加快了工程进度。 相似文献
80.
The bond strength and slip of epoxy-coated reinforcing bars in concrete have been evaluated by carrying out single pullout and double pullout tests. In extended single pullout tests, slip measurements were made while tensile force was applied to reinforcing bars embedded in concrete. In double pullout tests, 20 cycles of load were applied at levels of steel stress between zero and 0·5 times characteristic steel strength. Strains were measured by electrical resistance strain gauges glued inside the bars. Both epoxy-coated and uncoated bars were used in the investigation, to obtain comparative results. The strain gradient along the bar was found to be less for the coated reinforcement. In general, the epoxy coating was found to increase slip in bond and thereby reduce the bond performance of coated bars. 相似文献