全文获取类型
收费全文 | 2846篇 |
免费 | 128篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 101篇 |
综合类 | 4篇 |
化学工业 | 684篇 |
金属工艺 | 89篇 |
机械仪表 | 102篇 |
建筑科学 | 76篇 |
矿业工程 | 2篇 |
能源动力 | 225篇 |
轻工业 | 301篇 |
水利工程 | 34篇 |
石油天然气 | 31篇 |
无线电 | 299篇 |
一般工业技术 | 513篇 |
冶金工业 | 228篇 |
原子能技术 | 16篇 |
自动化技术 | 284篇 |
出版年
2024年 | 6篇 |
2023年 | 34篇 |
2022年 | 60篇 |
2021年 | 129篇 |
2020年 | 86篇 |
2019年 | 86篇 |
2018年 | 132篇 |
2017年 | 108篇 |
2016年 | 106篇 |
2015年 | 84篇 |
2014年 | 105篇 |
2013年 | 282篇 |
2012年 | 203篇 |
2011年 | 192篇 |
2010年 | 141篇 |
2009年 | 135篇 |
2008年 | 110篇 |
2007年 | 95篇 |
2006年 | 84篇 |
2005年 | 70篇 |
2004年 | 51篇 |
2003年 | 61篇 |
2002年 | 47篇 |
2001年 | 46篇 |
2000年 | 49篇 |
1999年 | 31篇 |
1998年 | 74篇 |
1997年 | 46篇 |
1996年 | 39篇 |
1995年 | 39篇 |
1994年 | 21篇 |
1993年 | 30篇 |
1992年 | 8篇 |
1991年 | 15篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 23篇 |
1987年 | 22篇 |
1986年 | 17篇 |
1985年 | 12篇 |
1984年 | 16篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1973年 | 3篇 |
排序方式: 共有2989条查询结果,搜索用时 15 毫秒
31.
The subcellular distribution in rat liver and the topography in intracellular and plasma membranes of connexin 32, a major protein component of gap junctions, was studied using sequence-specific anti-peptide antibodies generated to extracellular and intracellular domains of the protein. The distribution of connexin 32 in liver analyzed using SDS-polyacrylamide gel electrophoresis and Western blotting showed the relative protein levels in the subcellular fractions to be: lateral plasma membranes > Golgi membranes > sinusoidal plasma membranes > lysosomes. Low amounts of connexin 32 were detected in microsomes, endosomes, and bile canalicular plasma membranes. Six highly conserved cysteine residues are located in the amino acid sequences comprising the two extracellular loops of all connexins thus far isolated, and these loops are positioned to extend the channel in the lipid bilayers across the intercellular region of the gap junction. In the present work, the intramolecular disulfide bonds linking the extracellular loops in gap junctions were shown to be present in connexins located in plasma membranes, Golgi, and a microsomal fraction, and it was concluded that the disulfide linkages were formed in the endoplasmic reticulum. In addition, immature configurations of connexin 32, probably occurring during membrane insertion, were detected in liver microsomal fractions. The results contribute to charting of the biogenetic routes followed by connexins in hepatocytes and the general mechanisms of gap junction assembly. 相似文献
32.
33.
34.
35.
To study the conservation of peroxisomal targeting signals, we have determined the intracellular localization of human peroxisomal catalase when expressed in yeast. Using immunofluorescence, differential centrifugation and immunoelectron microscopy, we show that the protein is targeted to the peroxisomes of the heterologous cell and assembled in its active tetrameric form. These data show the conservation of the catalase targeting signal and import specificity between human and yeast peroxisomes. 相似文献
36.
Sharma Rashmi Nitin Nitin AlShehri Mohammed Abdul Rahman Dahiya Deepak 《The Journal of supercomputing》2021,77(1):890-908
The Journal of Supercomputing - Multiple tasks arrive in the distributed systems that can be executed in either parallel or sequential manner. Before the execution, tasks are scheduled prioritywise... 相似文献
37.
Ali Karime M. Anwar Hossain A. S. M. Mahfujur Rahman Wail Gueaieb Jihad Mohamed Alja’am Abdulmotaleb El Saddik 《Multimedia Tools and Applications》2012,59(3):749-774
In this paper, we present an interactive edutainment system for the children that leverages multimedia and RFID technologies in a seamless manner. The proposed system allows children to learn about new objects/entities by tapping on physical objects through a specially designed RFID-Bluetooth based Tangible User Interface (TUI) tool. The output of the system is delivered as a set of appropriate multimedia representations related to the objects being tapped. The TUI uses RFID technology for object identification and Bluetooth communication to transmit data to the computer where the system??s software is running. We incorporated our system in three games that allow children of different ages to benefit from the system??s functionalities and encourage them to interact with it. 相似文献
38.
Clones are generally considered bad programming practice in software engineering folklore. They are identified as a bad smell?(Fowler et?al. 1999) and a major contributor to project maintenance difficulties. Clones inherently cause code bloat, thus increasing project size and maintenance costs. In this work, we try to validate the conventional wisdom empirically to see whether cloning makes code more defect prone. This paper analyses the relationship between cloning and defect proneness. For the four medium to large open source projects that we studied, we find that, first, the great majority of bugs are not significantly associated with clones. Second, we find that clones may be less defect prone than non-cloned code. Third, we find little evidence that clones with more copies are actually more error prone. Fourth, we find little evidence to support the claim that clone groups that span more than one file or directory are more defect prone than collocated clones. Finally, we find that developers do not need to put a disproportionately higher effort to fix clone dense bugs. Our findings do not support the claim that clones are really a “bad smell”?(Fowler et?al. 1999). Perhaps we can clone, and breathe easily, at the same?time. 相似文献
39.
In this study, Adaptive Neuro-Fuzzy Inference System (ANFIS) has been used to model local scouring depth and pattern scouring around concave and convex arch shaped circular bed sills. The experimental part of this research study includes seven sets of laboratory test cases which were performed in an experimental flume under different flow conditions. A data set consists of 2754 data points of scouring depth were collected to use in the ANFIS model. The ratio of arch diameter, D, to flume width, W, is used as a non dimensional variables in all test cases. The results from ANFIS model were compared with the results of ANN model obtained by Homayoon et al. [24] and previously presented models. The results indicated that for D/W equal to 1 and 1.2, the ANFIS models produced a good performance for convex and concave bed sills. As a result, the ANFIS models can be used as an alternative to ANN for estimation of scour depth and scour pattern around a concave bed sill installed with a bridge pier. 相似文献
40.
James?Eves Vassili?V.?ToropovEmail author Harvey?M.?Thompson Nik?Kapur Jian?Fan Daniel?Copley Adrian?Mincher 《Structural and Multidisciplinary Optimization》2012,45(5):739-745
Supersonic jet pumps are simple devices with no moving parts, where a high velocity (primary) flow is used to pump a second
fluid. In this paper, Computational Fluid Dynamics (CFD) is combined with an optimization framework in order to develop a
tool for the rapid generation of jet pump designs. A key feature of the problem formulation is the transformation of the jet
pump design parameters in terms of geometric ratios. This approach dramatically reduces the number of unrealistic designs
covered by the Design of Experiments. Optimal Latin Hypercubes for surrogate model building and model validation points are
constructed using a permutation genetic algorithm and design points are evaluated using CFD. Surrogate models of primary and
entrained flow rates are built using a Moving Least Squares approach. A series of optimizations for various pump sizes are
performed using a genetic algorithm and Sequential Quadratic Programming, with responses calculated from the surrogates. This
approach results in a set of optimized designs, from which pumps for a wide range of flow rates can be interpolated. 相似文献