全文获取类型
收费全文 | 302835篇 |
免费 | 3812篇 |
国内免费 | 830篇 |
专业分类
电工技术 | 5113篇 |
综合类 | 173篇 |
化学工业 | 48302篇 |
金属工艺 | 12141篇 |
机械仪表 | 8878篇 |
建筑科学 | 7294篇 |
矿业工程 | 1873篇 |
能源动力 | 7007篇 |
轻工业 | 28645篇 |
水利工程 | 3342篇 |
石油天然气 | 7147篇 |
武器工业 | 18篇 |
无线电 | 32101篇 |
一般工业技术 | 59156篇 |
冶金工业 | 55191篇 |
原子能技术 | 7584篇 |
自动化技术 | 23512篇 |
出版年
2021年 | 2470篇 |
2019年 | 2328篇 |
2018年 | 4269篇 |
2017年 | 4212篇 |
2016年 | 4502篇 |
2015年 | 2925篇 |
2014年 | 4839篇 |
2013年 | 13179篇 |
2012年 | 7741篇 |
2011年 | 9994篇 |
2010年 | 8208篇 |
2009年 | 9282篇 |
2008年 | 9543篇 |
2007年 | 9398篇 |
2006年 | 8192篇 |
2005年 | 7615篇 |
2004年 | 7105篇 |
2003年 | 6838篇 |
2002年 | 6875篇 |
2001年 | 6666篇 |
2000年 | 6332篇 |
1999年 | 6449篇 |
1998年 | 15982篇 |
1997年 | 11787篇 |
1996年 | 9050篇 |
1995年 | 6785篇 |
1994年 | 6146篇 |
1993年 | 6028篇 |
1992年 | 4540篇 |
1991年 | 4522篇 |
1990年 | 4353篇 |
1989年 | 4374篇 |
1988年 | 4324篇 |
1987年 | 3660篇 |
1986年 | 3653篇 |
1985年 | 4225篇 |
1984年 | 4005篇 |
1983年 | 3649篇 |
1982年 | 3471篇 |
1981年 | 3616篇 |
1980年 | 3469篇 |
1979年 | 3385篇 |
1978年 | 3467篇 |
1977年 | 4017篇 |
1976年 | 5218篇 |
1975年 | 3171篇 |
1974年 | 3020篇 |
1973年 | 3033篇 |
1972年 | 2656篇 |
1971年 | 2474篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
121.
The biological decolorization of two industrial, spent textile reactive dyebaths was investigated using a suspended-growth, halophilic mixed culture fed with glucose. Dyebath I contained mainly Reactive Blue 19 (RB19), an anthraquinone dye, whereas dyebath II contained mainly Reactive Blue 21 (RB21), a phthalocyanine dye. Batch assays under anaerobic conditions with the two neutralized dyebaths resulted in 87 and 37% extent of decolorization for dyebaths I and II, respectively. The rate of glucose utilization and the extent of acetate production were impacted in the presence of each dyebath as compared to the control culture. However, dyebath decolorization occurred despite moderate culture inhibition. Reuse of a biologically renovated RB19-containing dyebath in the dyeing process resulted in reproducible but not identical cotton fabric shades as compared to a standard dyeing (i.e., control) using fresh water. This difference is attributed to a variable degree of RB19 aggregation during the dyeing process and is not related to the efficiency of the biodecolorization process. Further improvement of the redyeing efficiency will lead to the development of an in-plant, closed-loop decolorization system resulting in significant water conservation and minimization of textile pollutants such as salt and dyes. 相似文献
122.
123.
124.
125.
126.
127.
The shape of the impactor with the maximum depth of penetration (DOP) for a given impact velocity is found using a numerical procedure for solving a corresponding non-classical variational problem. It is shown that the optimum shape in a general case is close to a blunt cone. The variation of the optimal shape of the impactor and the dependence of the DOP vs. the initial (impact) velocity and friction coefficient is studied. The analysis is performed also for optimal conical impactors. 相似文献
128.
The results of a comparative numerical investigation of three types of resonator systems of a cyclotron for acceleration of negative hydrogen and deuterium ions up to maximum energy 30 and 15 MeV, respectively, are presented. It is shown that a vertical system with two half-wave resonators excited in-phase has the smallest active losses and the smallest differential of the amplitude of the accelerating voltage along the edge of the dees and is effective for accelerating particles at dual working frequencies. 相似文献
129.
O Prez‐Camacho S Sepúlveda‐Guzmn M Prez‐lvarez M García‐Zamora G Cadenas‐Pliego 《Polymer International》2005,54(12):1626-1631
New functionalized styrene–maleimide copolymers were prepared by free radical copolymerization of styrene (St) and N‐4‐carboxybutylmaleimide (NBMI) in chloroform, using 2,2′‐azobisisobutyronitrile (AIBN) as initiator. Monomer and copolymer characterization was carried out by 1H‐ and 13C‐NMR. Copolymer composition was determined by elemental analysis and Fourier‐transform infrared (FTIR) spectroscopy. The glass transition temperature (from DSC) and the thermogravimetric analysis (TGA) of the copolymers were consistent with the thermal behavior and stability observed for alternating St–maleimide copolymers. St–NBMI copolymers crosslinked with divinylbenzene (DVB) were also synthesized and their cation exchange properties evaluated in order to assess the capacity of the new copolymers to bind metallic ions. Copyright © 2005 Society of Chemical Industry 相似文献
130.
The Metaflow architecture, a unified approach to maximizing the performance of superscalar microprocessors, is introduced. The Metaflow architecture exploits inherent instruction-level parallelism in conventional sequential programs by hardware means, without relying on optimizing compilers. It is based on a unified structure, the DRIS (deferred-scheduling, register-renaming instruction shelf), that manages out-of-order execution and most of the attendant problems. Coupling the DRIS with a speculative-execution mechanism that avoids conditional branch stalls results in performance limited only be inherent instruction-level parallelism and available execution resources. Although presented in the context of superscalar machines, the technique is equally applicable to a superpipelined implementation. Lightning, the first implementation of the Metaflow architecture, which executes the Sparc RISC instruction set is described 相似文献