全文获取类型
收费全文 | 21443篇 |
免费 | 2363篇 |
国内免费 | 2968篇 |
专业分类
电工技术 | 1592篇 |
综合类 | 4394篇 |
化学工业 | 3577篇 |
金属工艺 | 1238篇 |
机械仪表 | 1663篇 |
建筑科学 | 507篇 |
矿业工程 | 447篇 |
能源动力 | 1356篇 |
轻工业 | 2323篇 |
水利工程 | 209篇 |
石油天然气 | 633篇 |
武器工业 | 245篇 |
无线电 | 2209篇 |
一般工业技术 | 2951篇 |
冶金工业 | 473篇 |
原子能技术 | 127篇 |
自动化技术 | 2830篇 |
出版年
2024年 | 109篇 |
2023年 | 531篇 |
2022年 | 806篇 |
2021年 | 931篇 |
2020年 | 1036篇 |
2019年 | 749篇 |
2018年 | 746篇 |
2017年 | 876篇 |
2016年 | 1003篇 |
2015年 | 1085篇 |
2014年 | 1777篇 |
2013年 | 1882篇 |
2012年 | 2170篇 |
2011年 | 2396篇 |
2010年 | 1588篇 |
2009年 | 1742篇 |
2008年 | 1180篇 |
2007年 | 1589篇 |
2006年 | 1342篇 |
2005年 | 545篇 |
2004年 | 265篇 |
2003年 | 224篇 |
2002年 | 219篇 |
2001年 | 174篇 |
2000年 | 201篇 |
1999年 | 171篇 |
1998年 | 146篇 |
1997年 | 155篇 |
1996年 | 138篇 |
1995年 | 149篇 |
1994年 | 96篇 |
1993年 | 113篇 |
1992年 | 96篇 |
1991年 | 72篇 |
1990年 | 64篇 |
1989年 | 72篇 |
1988年 | 56篇 |
1987年 | 100篇 |
1986年 | 88篇 |
1985年 | 19篇 |
1984年 | 14篇 |
1983年 | 4篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 7篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
目的筛选出口蹄疫病毒(FMDV)基因组上适于设计siRNA的基因片段。方法以FMDV WFL株RNA为模板,用3′RACE法扩增出2C-P3-3′NCR序列,将PCR扩增片段克隆到pMD18-T载体上,转化E.coli DH5α,筛选阳性重组子,进行序列测定,并与参考毒株序列比较。结果扩增的基因片段大小为4033bp,其2C、P3和3′NCR序列的核苷酸序列与参考毒株的同源性分别为87·11%~94·23%、84·91%~96·66%和66·98%~82·35%,2C和P3与参考毒株的氨基酸同源性分别为94·97%~99·39%和91·84%~98·55%,WFL株P3基因的第1150~1270、1680~1840和2080~2490bp以及2C基因的第354~470bp范围内与参考毒株具有高度保守的特性。因此,可以依据siRNA设计原则,在这4个区域内筛选抑制效果好的siRNA。结论成功克隆了FMDV WFL株2C-P3-3′NCR基因的序列,并筛选出4个适于设计siRNA的基因区段。 相似文献
103.
《Automatica》2014,50(12):3019-3029
An adaptive control algorithm for open-loop stable, constrained, linear, multiple input multiple output systems is presented. The proposed approach can deal with both input and output constraints, as well as measurement noise and output disturbances. The adaptive controller consists of an iterative set membership identification algorithm, that provides a set of candidate plant models at each time step, and a model predictive controller, that enforces input and output constraints for all the plants inside the model set. The algorithm relies only on the solution of standard convex optimization problems that are guaranteed to be recursively feasible. The experimental results obtained by applying the proposed controller to a quad-tank testbed are presented. 相似文献
104.
目的构建真核表达质粒pcDNA3.1(+)-Vasostatin并检测其在真核细胞内的表达水平。方法将带有信号肽的Vasostatin基因片段克隆至pcDNA3.1(+)真核表达载体上,经酶切鉴定及测序分析证明构建成功后,以脂质体介导法转染293T细胞,通过Westernblot法,检测其在293T细胞内的表达水平。结果所构建的真核表达质粒pcDNA3.1(+)-Va-sostatin转染293T细胞后,在其裂解的上清液中,检测到目的基因的表达。结论已成功构建了pcDNA3.1(+)-Vasostatin表达载体,并在真核细胞中表达了目的蛋白。 相似文献
105.
《Expert systems with applications》2014,41(6):2947-2956
To enable the immediate and efficient dispatch of relief to victims of disaster, this study proposes a greedy-search-based, multi-objective, genetic algorithm capable of regulating the distribution of available resources and automatically generating a variety of feasible emergency logistics schedules for decision-makers. The proposed algorithm dynamically adjusts distribution schedules from various supply points according to the requirements at demand points in order to minimize unsatisfied demand for resources, time to delivery, and transportation costs. The proposed algorithm was applied to the case of the Chi–Chi earthquake in Taiwan to verify its performance. Simulation results demonstrate that under conditions of a limited/unlimited number of available vehicles, the proposed algorithm outperforms the MOGA and standard greedy algorithm in ‘time to delivery’ by an average of 63.57% and 46.15%, respectively, based on 10,000 iterations. 相似文献
106.
《Expert systems with applications》2014,41(6):3134-3142
Partitioning the universe of discourse and determining intervals containing useful temporal information and coming with better interpretability are critical for forecasting in fuzzy time series. In the existing literature, researchers seldom consider the effect of time variable when they partition the universe of discourse. As a result, and there is a lack of interpretability of the resulting temporal intervals. In this paper, we take the temporal information into account to partition the universe of discourse into intervals with unequal length. As a result, the performance improves forecasting quality. First, time variable is involved in partitioning the universe through Gath–Geva clustering-based time series segmentation and obtain the prototypes of data, then determine suitable intervals according to the prototypes by means of information granules. An effective method of partitioning and determining intervals is proposed. We show that these intervals carry well-defined semantics. To verify the effectiveness of the approach, we apply the proposed method to forecast enrollment of students of Alabama University and the Taiwan Stock Exchange Capitalization Weighted Stock Index. The experimental results show that the partitioning with temporal information can greatly improve accuracy of forecasting. Furthermore, the proposed method is not sensitive to its parameters. 相似文献
107.
超滤-反渗透集成工艺处理玉米酒糟废水 总被引:1,自引:0,他引:1
研究了玉米酒精生产过程中产生的玉米酒糟废水的膜分离过程,开发了处理玉米酒糟废水的超滤-反渗透集成工艺。超滤选用截留相对分子质量为6 000的GR81PP膜平板分离器,入口压力控制为0.6 MPa,操作温度为50℃;反渗透选用标准脱盐率为90%的ESNAI-4040卷式膜分离器,入口压力控制为2.2 MPa,操作温度为40℃。反渗透透过液中蛋白质的平均截留率为94.70%,甘油的平均截留率为65.15%,COD值降到1 000 mg/L左右,可作为工艺回用水,而且反渗透浓缩液中可回收甘油等有用物质,超滤浓缩液可浓缩成饲料,节能效果显著。 相似文献
108.
109.
In this paper, a lattice Boltzmann model for the three-dimensional complex Ginzburg–Landau equation is proposed. The multi-scale technique and the Chapman–Enskog expansion are used to describe higher-order moments of the complex equilibrium distribution function and a series of complex partial differential equations. The modified partial differential equation of the three-dimensional complex Ginzburg–Landau equation with the third order truncation error is obtained. Based on the complex lattice Boltzmann model, some motions of the stable scroll, such as the scroll wave with a straight filament, scroll ring, and helical scroll are simulated. The comparisons between results of the lattice Boltzmann model with those obtained by the alternative direction implicit scheme are given. The numerical results show that this model can be used to simulate the three-dimensional complex Ginzburg–Landau equation. 相似文献
110.
Zeyun Yu Jun Wang Zhanheng Gao Ming Xu Masahiko Hoshijima 《Computer methods and programs in biomedicine》2014
In this paper we present a new software toolkit for generating and optimizing surface and volumetric meshes from three-dimensional (3D) biomedical imaging data, targeted at image-based finite element analysis of some biomedical activities in a single material domain. Our toolkit includes a series of geometric processing algorithms including surface re-meshing and quality-guaranteed tetrahedral mesh generation and optimization. All methods described have been encapsulated into a user-friendly graphical interface for easy manipulation and informative visualization of biomedical images and mesh models. Numerous examples are presented to demonstrate the effectiveness and efficiency of the described methods and toolkit. 相似文献