全文获取类型
收费全文 | 1270篇 |
免费 | 125篇 |
国内免费 | 20篇 |
专业分类
电工技术 | 48篇 |
综合类 | 27篇 |
化学工业 | 271篇 |
金属工艺 | 30篇 |
机械仪表 | 55篇 |
建筑科学 | 36篇 |
矿业工程 | 14篇 |
能源动力 | 65篇 |
轻工业 | 323篇 |
水利工程 | 9篇 |
石油天然气 | 27篇 |
武器工业 | 3篇 |
无线电 | 65篇 |
一般工业技术 | 187篇 |
冶金工业 | 98篇 |
原子能技术 | 15篇 |
自动化技术 | 142篇 |
出版年
2024年 | 13篇 |
2023年 | 47篇 |
2022年 | 114篇 |
2021年 | 138篇 |
2020年 | 76篇 |
2019年 | 72篇 |
2018年 | 41篇 |
2017年 | 41篇 |
2016年 | 41篇 |
2015年 | 35篇 |
2014年 | 49篇 |
2013年 | 222篇 |
2012年 | 55篇 |
2011年 | 77篇 |
2010年 | 67篇 |
2009年 | 55篇 |
2008年 | 31篇 |
2007年 | 38篇 |
2006年 | 33篇 |
2005年 | 18篇 |
2004年 | 20篇 |
2003年 | 12篇 |
2002年 | 18篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 12篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1992年 | 3篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1932年 | 1篇 |
1927年 | 1篇 |
1919年 | 1篇 |
1909年 | 1篇 |
排序方式: 共有1415条查询结果,搜索用时 15 毫秒
61.
62.
走滑断裂带作为一个空间地质体,具备物理-化学机制下的增容作用,可以在断裂带内部形成独特的缝洞系统及伴生孔洞、孔隙空间,塔里木盆地顺北地区发育超深碳酸盐岩断溶体相关的缝洞系统,其储集体与断裂带活动关系密切。以顺北地区走滑断裂带为研究对象,综合近年来对走滑断裂带解析及勘探实践认识,分析走滑断裂带内部结构,探讨断溶体(储集体)发育特征及成因。其断溶体空间展布明显受到走滑断裂带边界的约束,储集体的外在轮廓主要受断裂带控制,宽度相对窄,纵向发育深度大。其储集空间主要由多期走滑构造破裂作用与断裂带内物质体积调整形成的“空腔”型洞穴和缝网系统组成,并经历了多类型流体的溶蚀-胶结作用叠加改造,形成了在断裂带内沿着断层发育的裂缝-洞穴系统,并伴生发育溶蚀孔洞与各类孔隙空间,导致断溶体内部储集体结构复杂化。根据断裂带内部流体参与程度和流体类型不同,可以细分出3种成因机制的端元模型:断容型、岩溶型和热溶型。断溶体的形成机制可以是其中的一种,也可以是2种或3种类型的组合。断溶体与岩溶缝洞储层最本质的差异在于,前者缝洞系统的构成和储集规模的形成与断裂活动关系密切,后者则主要取决于水-岩作用的方式和所能带走的物质体积总和。 相似文献
63.
油气二次运移的方式和方向对具体指出盆地油气资源量所赋存的位置有决定性的意义.在运载层中推动油气运动的作用力主要是浮力和毛细管力,而盖层则起着毛细管阻力作用.因此盖层的形状及空间分布就成了影响运移路径重要的封盖因素.该文试图根据盖层的几何形状特性,建立运移路径模拟模型,开发微机软件运行实施.在一个具体盆地进行运移路径模拟应用的结果反映,与已知勘探情况基本符合,能够检验油气期次性运移的地质概念,可以揭示运移过程,预测可能的运移聚集位置. 相似文献
64.
65.
The behaviour of two‐phase gas‐liquid flows in a stopper‐rod controlled submerged entry nozzle (SEN) is investigated in water model experiments. The observed two‐phase flow patterns can be classified into either bubble coring or bubbly slug. The scaling of the two‐phase flows by means of similarity parameters is discussed. In the experiments, it is found that the liquid flow rates depend strongly on the two‐phase flow patterns. Additionally, the influence of swirl on the flow patterns is investigated in detail. It is shown that swirl has a marked impact on the transition from bubble coring to bubbly slug. Finally, an estimation of the two‐phase argon‐steel flow patterns in industrialscale SEN flows is given. 相似文献
66.
Approximately 40% of the heavy industry in Turkey was located in the region affected by the 1999 Mw 7.4 Kocaeli earthquake. Twenty-four facilities representing different industries in the epicentral region were surveyed after the earthquake. Structural and nonstructural damage to these facilities is summarized and performance is reported using a damage classification scheme. Information on typical industrial-facility construction practice in Turkey is presented. Earthquake damage to the most common structural framing systems is highlighted. The structural performance of a small number of the facilities visited by the reconnaissance team is investigated. 相似文献
67.
This study presents both a numerical and an experimental solution to seepage from a rectangular ditch or elongated pond to a groundwater table of infinite horizontal extent. Because of the unknown location of the free surface, the flow domain is transformed into the complex potential plane using the inverse formulation method, where the free surface becomes a straight line. The method of finite differences was used to solve the boundary value problem. The problem was also investigated experimentally using a sand tank model. For comparison purposes, a one-dimensional analytical solution is also presented. The results were compared with each other and with those available in the literature obtained with other solution techniques. The parameters affecting the seepage rate were investigated and the resulting relationships are presented in dimensionless graphs. It is believed that these graphs may be of use in design problems. The conditions for which the simplified one-dimensional analytical solution agrees well with the results of the sophisticated two-dimensional numerical solution are identified. 相似文献
68.
Mustafa Übeyli 《Journal of Fusion Energy》2003,22(1):51-57
In a commercial (DT) driven fusion reactor, the tritium breeding ratio per incident fusion neutron must be greater than 1.05 to maintain tritium self-sufficiency for the driver. In this study tritium breeding capability of three different coolants, namely Flibe (LiF·BeF2), Flinabe (LiF·NaF·BeF2), and Li20Sn80 in a (DT) driven fusion-fission (hybrid) reactor was investigated for different refractory alloys (W-5Re, TZM, T111, and Nb-1Zr) as structural material. Neutron transport calculations were conducted with the help of SCALE 4.3 SYSTEM by solving the Boltzmann transport equation with code XSDRNPM. The contribution of Flibe, Flinabe, and Li20Sn80 with respect to 6Li enrichment in their lithium content to overall TBR was investigated. In addition, the effect of structural material type on TBR was examined. 相似文献
69.
A canonical form for controllable singular systems modulo restricted system equivalence is presented. The canonical form respects the decomposition of the singular system into a regular and an impulsive part. The construction is based on Popov's control canonical form and on the Jordan canonical form recently developed by Hinrichsen and Prätzel-Wolters. Continuity properties are analysed and the cellular partition of the orbit space induced by the canonical form is briefly discussed. 相似文献
70.
食用菌营养丰富,是优质蛋白质的潜在来源。本研究以18个常见食用菌品种为研究对象,分析了食用菌中的水分、灰分、蛋白、总糖和L-麦角硫因等营养成分,并采用顶空固相微萃取结合气相色谱-质谱联用法(HS-SPME-GC-MS)分析了其中6种食用菌子实体、菌丝体及发酵液的风味物质。结果表明,18种食用菌水分含量为6.7~13.77 g/100 g、灰分含量为2.24~10.9 g/100 g、脂肪含量为0.3~2.92 g/100 g、总糖含量为2.11~10.5 g/100 g。粗蛋白含量在7.88~35.87 g/100 g之间,其中双孢菇的蛋白质含量高达35.87 g/100 g。氨基酸种类齐全、含量丰富且含有人体必需的8种必需氨基酸。主成分分析表明香菇、黑木耳、灰树花、草菇和金针菇等食用菌的氨基酸组成比例与鸡蛋最相似,但与肉类、大豆和小麦等氨基酸组成相差较大。高效液相色谱结果表明香菇中富含麦角硫因,含量高达336 mg/kg,且灰树花、羊肚菌、双孢菇和鸡腿菇的麦角硫因含量也高于100 mg/kg。HS-SPME-GC-MS在6种食用菌中共鉴定出34种主要挥发性化合物,包括醛类、酮类、酯类、醇类、酚类、醚类、烷烃类和杂环化合物。灵芝菌丝体富含己醛、甲基壬基甲酮、反-2-辛烯醛、2-正戊基呋喃、2,4-壬二烯醛等成分,与其他17种样品有明显差异;6种食用菌发酵液的风味物质相似,均具有庚酸乙酯、18-冠醚-6等特有风味物质;而灵芝、鸡腿菇子实体以及杏鲍菇菌丝具有2,6-二叔丁基对甲酚、苯甲酸甲酯等特有风味。本研究通过分析常见食用菌的营养成分及风味物质,为食用菌的高值化开发提供了数据基础。 相似文献