全文获取类型
收费全文 | 9762篇 |
免费 | 91篇 |
专业分类
电工技术 | 71篇 |
综合类 | 1篇 |
化学工业 | 667篇 |
金属工艺 | 83篇 |
机械仪表 | 91篇 |
建筑科学 | 169篇 |
矿业工程 | 17篇 |
能源动力 | 83篇 |
轻工业 | 471篇 |
水利工程 | 53篇 |
石油天然气 | 16篇 |
无线电 | 606篇 |
一般工业技术 | 752篇 |
冶金工业 | 6066篇 |
原子能技术 | 40篇 |
自动化技术 | 667篇 |
出版年
2021年 | 43篇 |
2020年 | 30篇 |
2019年 | 65篇 |
2018年 | 68篇 |
2017年 | 50篇 |
2016年 | 51篇 |
2015年 | 42篇 |
2014年 | 70篇 |
2013年 | 218篇 |
2012年 | 120篇 |
2011年 | 172篇 |
2010年 | 127篇 |
2009年 | 123篇 |
2008年 | 179篇 |
2007年 | 179篇 |
2006年 | 162篇 |
2005年 | 142篇 |
2004年 | 118篇 |
2003年 | 112篇 |
2002年 | 113篇 |
2001年 | 118篇 |
2000年 | 97篇 |
1999年 | 256篇 |
1998年 | 1766篇 |
1997年 | 1021篇 |
1996年 | 669篇 |
1995年 | 451篇 |
1994年 | 361篇 |
1993年 | 425篇 |
1992年 | 137篇 |
1991年 | 118篇 |
1990年 | 137篇 |
1989年 | 167篇 |
1988年 | 134篇 |
1987年 | 140篇 |
1986年 | 109篇 |
1985年 | 135篇 |
1984年 | 75篇 |
1983年 | 70篇 |
1982年 | 69篇 |
1981年 | 77篇 |
1980年 | 79篇 |
1979年 | 63篇 |
1978年 | 60篇 |
1977年 | 185篇 |
1976年 | 366篇 |
1975年 | 57篇 |
1974年 | 37篇 |
1973年 | 37篇 |
1972年 | 37篇 |
排序方式: 共有9853条查询结果,搜索用时 6 毫秒
61.
62.
Yong-Jik KimJames H. Anderson 《Information Processing Letters》2002,84(1):47-55
A simple code transformation is presented that reduces the space complexity of Yang and Anderson's local-spin mutual exclusion algorithm. In both the original and the transformed algorithm, only atomic read and write instructions are used; each process generates Θ(logN) remote memory references per lock request, where N is the number of processes. The transformed algorithm uses Θ(N) distinct variables, which is clearly optimal. 相似文献
63.
64.
Bilateral control of teleoperators with time delay 总被引:5,自引:0,他引:5
A control law for teleoperators is presented which overcomes the instability caused by time delay. By using passivity and scattering theory, a criterion is developed which shows why existing bilateral control systems are unstable for certain environments, and why the proposed bilateral control law is stable for any environment and any time delay. The control law has been implemented on a single-axis force-reflecting hand controller, and preliminary results are shown. To keep the presentation clear, a single-degree-of-freedom (DOF) linear time-invariant (LTI) teleoperator system is discussed. Nevertheless, results can be extended, without loss of generality, to an n -DOF nonlinear teleoperation system 相似文献
65.
JD Haag LA Shepel BD Kolman DM Monson ME Benton KT Watts JL Waller CC Lopez-Guajardo DJ Samuelson MN Gould 《Canadian Metallurgical Quarterly》2003,63(18):5808-5812
It has previously been shown that the Copenhagen (COP) rat contains several genetic loci that contribute to its mammary tumor-resistant phenotype after 7,12-dimethylbenz(a)anthracene (DMBA) administration. One of these loci, mammary carcinoma susceptibility 1 (Mcs1), is located on the centromeric end of chromosome 2 and appears to act in a semidominant fashion. To confirm the existence and independent action of this locus and also aid in the identification of the physical location of the Mcs1 gene, congenic lines were generated by transferring the Mcs1 COP allele onto a Wistar Furth (WF) genetic background. Male carriers were genotyped using microsatellite markers spanning 20-30 cM of the Mcs1 locus. One of the congenic lines minimally retained the COP allele at D2Mit29 on the centromeric end of chromosome 2 and extended distally to D2Rat201. Heterozygous Mcs1 carrier rats were interbred, and the female offspring were treated with DMBA. The female rats from the Mcs1 congenic line that carried one or two COP alleles of the Mcs1 region had a significantly reduced (65 and 85%, respectively) tumor development (P < 0.001) compared with rats carrying zero COP alleles at this locus. A WF.COP-D2Mit29/D2Rat201 homozygous congenic strain derived at the N10 generation was treated with DMBA, and the COP homozygous rats developed 1.5 +/- 0.3 carcinomas/rat versus 6.3 +/- 0.5 in WF control rats (P < 0.0001). Fine mapping of this congenic interval using several recombinant lines identified three genetic loci within the Mcs1 congenic region that independently supported a tumor resistance phenotype. These genetic loci have been termed Mcs1a, Mcs1b, and Mcs1c. In rats for which each locus was homozygous for the COP allele, tumor development was reduced by approximately 60% compared with littermate controls. The identification of these independent loci within the Mcs1 COP allele provide a model of the genetic complexity of cancer. 相似文献
66.
Four studies involving 573 female and 272 male college students demonstrated that multiple forms and measures of aggression were associated with high levels of sensation seeking, impulsivity, and a focus on the immediate consequences of behavior. Multiple regression analyses and structural equation models supported a theoretical model based on the general aggression model (C. A. Anderson & B. J. Bushman, 2002), positing that hostile cognition and negative affect mediate the relationships between the aforementioned individual differences and aggression. Sensation seeking also predicted a desire to engage in physical and verbal aggression. The final study demonstrated that relative to those scoring low, individuals scoring high on the consideration of future consequences are only less aggressive when aggression is likely to carry future costs. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
67.
68.
G Hendrickson R K Anderson P D Clayton J Cimino G M Hripcsak S B Johnson M McCormack S Sengupta S Shea R Sideli 《M.D. computing : computers in medical practice》1992,9(1):35-42
Over the past seven years, Columbia-Presbyterian Medical Center has been planning and implementing an integrated academic information management system. Accomplishments to date include establishing an institutional information architecture, installing a campus-wide network of workstations, recruiting the staff needed to develop and implement the system, and developing various applications. This paper presents the rationale and steps involved in these accomplishments, as well as data on use of the system so far. 相似文献
69.
GL Anderson KN Caldwell LR Beuchat PL Williams 《Canadian Metallurgical Quarterly》2003,66(9):1543-1549
Free-living nematodes may harbor, protect, and disperse bacteria, including those ingested and passed in viable form in feces. These nematodes are potential vectors for human pathogens and may play a role in foodborne diseases associated with fruits and vegetables eaten raw. In this study, we evaluated the associations between a free-living soil nematode, Caenorhabditis elegans, and Escherichia coli, an avirulent strain of Salmonella Typhimurium, Listeria welshimeri, and Bacillus cereus. On an agar medium, young adult worms quickly moved toward colonies of all four bacteria; over 90% of 3-day-old adult worms entered colonies within 16 min after inoculation. After 48 h, worms moved in and out of colonies of L. welshimeri and B. cereus but remained associated with E. coli and Salmonella Typhimurium colonies for at least 96 h. Young adult worms fed on cells of the four bacteria suspended in K medium. Worms survived and reproduced with the use of nutrients derived from all test bacteria, as determined for eggs laid by second-generation worms after culturing for 96 h. Development was slightly slower for worms fed gram-positive bacteria than for worms fed gram-negative bacteria. Worms that fed for 24 h on bacterial lawns formed on tryptic soy agar dispersed bacteria over a 3-h period when they were transferred to a bacteria-free agar surface. The results of this study suggest that C. elegans and perhaps other free-living nematodes are potential vectors for both gram-positive and gram-negative bacteria, including foodborne pathogens in soil. 相似文献
70.