全文获取类型
收费全文 | 2109篇 |
免费 | 240篇 |
国内免费 | 55篇 |
专业分类
电工技术 | 17篇 |
技术理论 | 1篇 |
综合类 | 90篇 |
化学工业 | 611篇 |
金属工艺 | 12篇 |
机械仪表 | 92篇 |
建筑科学 | 93篇 |
矿业工程 | 14篇 |
能源动力 | 44篇 |
轻工业 | 831篇 |
水利工程 | 24篇 |
石油天然气 | 27篇 |
武器工业 | 14篇 |
无线电 | 54篇 |
一般工业技术 | 215篇 |
冶金工业 | 22篇 |
原子能技术 | 2篇 |
自动化技术 | 241篇 |
出版年
2024年 | 23篇 |
2023年 | 100篇 |
2022年 | 154篇 |
2021年 | 324篇 |
2020年 | 165篇 |
2019年 | 152篇 |
2018年 | 114篇 |
2017年 | 100篇 |
2016年 | 84篇 |
2015年 | 86篇 |
2014年 | 85篇 |
2013年 | 151篇 |
2012年 | 92篇 |
2011年 | 68篇 |
2010年 | 53篇 |
2009年 | 57篇 |
2008年 | 56篇 |
2007年 | 74篇 |
2006年 | 72篇 |
2005年 | 65篇 |
2004年 | 41篇 |
2003年 | 54篇 |
2002年 | 24篇 |
2001年 | 18篇 |
2000年 | 21篇 |
1999年 | 14篇 |
1998年 | 14篇 |
1997年 | 29篇 |
1996年 | 22篇 |
1995年 | 25篇 |
1994年 | 22篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有2404条查询结果,搜索用时 546 毫秒
1.
2.
以模拟生活污水为处理对象,三种不同填料为生物膜载体,运行 A、B、C三个SBBR,通过逐步降温(25、20、15、10、6和5℃)培养驯化处理低温污水的生物膜。运行251周期,三个反应器COD出水浓度均低于50 mg/L;B反应器对氨氮去除效果优于A和C。特别在低温5℃时,A、B和C三个反应器氨氮平均出水浓度分别为14.1、3.79和14.1 mg/L。高通量测序结果显示,5℃时,三个反应器中均以降解有机物的微生物为主;只有B反应器中驯化富集出了嗜冷硝化菌(Candidatus Nitrotoga);而其他有硝化作用的菌属在B反应器中的丰度也高于A和C反应器;不利于脱氮的类固氮菌(Elstera)在A和C反应器中丰度较高。此结果可从微生物角度解释三个反应器处理效果的差异性,表明B反应器处理低温污水有显著优势,其所用填料可结合低温菌进一步开发利用。 相似文献
3.
4.
以转基因水稻中最常用的CaMV35S启动子、NOS终止子、Cry1Ab/Ac基因、HPT基因及SPS水稻内标基因为研究对象,利用5 种不同的荧光信号(FAM、HEX、Taxas Red、Cy5、Cy5.5)进行多重实时聚合酶链式反应(real-time polymerase chain reaction,real-time PCR)检测方法的研究。通过引物组合筛选、反应体系优化、特异性测试、灵敏度测试、适用性测试等一系列实验,建立了5 重real-time PCR方法,灵敏度可达0.032%。此方法具有灵敏度高、结果准确、通量大等优点,可实现水稻中转基因成分的快速、高效检测。 相似文献
5.
6.
Bahram Rashidi 《International Journal of Circuit Theory and Applications》2020,48(8):1227-1243
In this paper, low-cost and two-cycle hardware structures of the PRINCE lightweight block cipher are presented. In the first structure, we proposed an area-constrained structure, and in the second structure, a high-speed implementation of the PRINCE cipher is presented. The substitution box (S-box) and the inverse of S-box (S-box−1) blocks are the most complex blocks in the PRINCE cipher. These blocks are designed by an efficient structure with low critical path delay. In the low-cost structure, the S-boxes and S-boxes−1 are shared between the round computations and the intermediate step of PRINCE cipher. Therefore, the proposed architecture is implemented based on the lowest number of computation resources. The two-cycle implementation of PRINCE cipher is designed by a processing element (PE), which is a general and reconfigurable element. This structure has a regular form with the minimum number of the control signal. Implementation results of the proposed structures in 180-nm CMOS technology and Virtex-4 and Virtex-6 FPGA families are achieved. The proposed structures, based on the results, have better critical path delay and throughput compared with other's related works. 相似文献
7.
Delevoye-Turrell Yvonne; Giersch Anne; Wing Alan M.; Danion Jean-Marie 《Canadian Metallurgical Quarterly》2007,116(1):56
Many everyday activities depend on the capacity to organize and smoothly execute motor sequences. The authors tested the hypothesis that a sequencing deficit is associated with schizophrenia. They used a new method to distinguish between lower and higher order mechanisms for the impairment. The 1st task involved triggered sequences in which sensory information from 1 movement was the cue for initiation of the following movement. Results showed that the motor sequences were performed as fluently in patients as in controls. The 2nd and 3rd tasks involved sequences in which the entire movement sequence could be preplanned. Patients executed the sequences less fluently than controls but only under the condition where action sequences were required. Furthermore, the patients' fluency deficit increased with sequence complexity. The high discrimination power of Task 3 gave the authors a means to control for a potential psychometric confound involving differential discriminating power and to argue in favor of a specific higher order motor fluency deficit in patients with schizophrenia. It is suggested that basic lower order mechanisms that integrate sensory information with outgoing motor commands are preserved in schizophrenia, whereas higher order integrative mechanisms that are required for the smooth coordination of motor sequences are impaired. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
Eugene Levner 《International Transactions in Operational Research》1994,1(2):241-250
This paper considers discrete search problems in which a decision-maker has to find objects lost or hidden in a given set of locations so as to minimize the expected losses incurred. Given a chance to look for a hidden object in the same location infinitely many times, this type of problem, in contrast to standard scheduling problems, has an infinite sequence as its solution. Thus we are concerned to find an algorithm that yields an optimal solution, rather than the optimal sequence itself. Using combinatorial techniques, fast optimal algorithms for solving the problems are obtained, and optimality conditions are presented for search criteria, under which the local-search algorithms yield the global optimum. 相似文献
9.
This paper presents the development of an optimization and a computer-simulation model to evaluate the process plans of a manufacturing center by analyzing the effect of tool failure on system performance. The GPSS/PC simulation program that is used in this study has been built with variables, functions and matrices so that many experiments could be conducted with the model. Sensitivity analysis is presented and the developed model has proven to be useful in determining optimum sequencing of parts for various operating policies. 相似文献
10.
Michael E. Cusick 《Yeast (Chichester, England)》1994,10(9):1251-1256
A 3·2 kb EcoRI fragment of yeast Saccharomyces cerevisiae was entirely sequenced. Two new open reading frames were identified. The first is extremely hydrophobic, and would likely be an integral membrane protein. It has significant similarity to only one reported gene, a gene of unknown function from Drosophila melanogaster. The second ORF is asparagine-rich and very serine-rich, with a remarkable stretch of nearly 26 consecutive asparagine residues comprised of the same codon. It has no significant similarity to any reported gene. The fragment maps to chromosome II on the left arm between the CDC27 and ILS1 loci. The nucleotide sequence reported in this paper has been deposited in the GenBank database with the Accession Number M89908. 相似文献