全文获取类型
收费全文 | 6723篇 |
免费 | 223篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 63篇 |
综合类 | 1篇 |
化学工业 | 1090篇 |
金属工艺 | 89篇 |
机械仪表 | 101篇 |
建筑科学 | 267篇 |
矿业工程 | 9篇 |
能源动力 | 152篇 |
轻工业 | 613篇 |
水利工程 | 44篇 |
石油天然气 | 8篇 |
无线电 | 494篇 |
一般工业技术 | 1009篇 |
冶金工业 | 2078篇 |
原子能技术 | 49篇 |
自动化技术 | 883篇 |
出版年
2022年 | 73篇 |
2021年 | 101篇 |
2020年 | 60篇 |
2019年 | 79篇 |
2018年 | 110篇 |
2017年 | 113篇 |
2016年 | 83篇 |
2015年 | 97篇 |
2014年 | 141篇 |
2013年 | 326篇 |
2012年 | 206篇 |
2011年 | 294篇 |
2010年 | 229篇 |
2009年 | 249篇 |
2008年 | 242篇 |
2007年 | 257篇 |
2006年 | 216篇 |
2005年 | 197篇 |
2004年 | 180篇 |
2003年 | 172篇 |
2002年 | 187篇 |
2001年 | 141篇 |
2000年 | 146篇 |
1999年 | 159篇 |
1998年 | 376篇 |
1997年 | 238篇 |
1996年 | 219篇 |
1995年 | 156篇 |
1994年 | 146篇 |
1993年 | 138篇 |
1992年 | 98篇 |
1991年 | 67篇 |
1990年 | 80篇 |
1989年 | 94篇 |
1988年 | 83篇 |
1987年 | 83篇 |
1986年 | 62篇 |
1985年 | 65篇 |
1984年 | 90篇 |
1983年 | 76篇 |
1982年 | 70篇 |
1981年 | 68篇 |
1980年 | 66篇 |
1979年 | 68篇 |
1978年 | 50篇 |
1977年 | 63篇 |
1976年 | 102篇 |
1975年 | 50篇 |
1974年 | 41篇 |
1972年 | 29篇 |
排序方式: 共有6950条查询结果,搜索用时 187 毫秒
31.
The authors used visual search tasks in which components of the classic flanker task (B. A. Eriksen & C. W. Eriksen, 1974) were introduced. In several experiments the authors obtained evidence of parallel search for a target among distractor elements. Therefore, 2-stage models of visual search predict no effect of the identity of those distractors. However, clear compatibility effects of the distractors were obtained: Responses were faster when the distractors were compatible with the response than when they were incompatible. These results show that even in parallel search tasks identity information is extracted from the distractors. In addition, alternative interpretations of the results in terms of the occasional identification of a distractor before or after the target was identified could be ruled out. The results showed that flat search slopes obtained in visual search experiments provide no benchmark for preattentive processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
32.
33.
N. E. Shchepina V. V. Avrorin G. A. Badun V. M. Fedoseev S. E. Ukhanov S. B. Lewis 《Radiochemistry》2007,49(6):630-632
Ion-molecule reactions of free phenyl cations with six-membered nitrogen-containing heterocyclic compounds: α-, β-, and γ-picolines, were studied. Phenyl cations were generated by tritium β-decay in double-labeled benzene. The mechanism of competing reactions of electrophilic addition to the nitrogen heteroatom in the ring and electrophilic substitution of the C-H bond in the pyridine ring was examined. The effect of methyl substituent in the pyridine molecule on the reaction pathway was evaluated. A one-step procedure for nuclear-chemical synthesis of tritium-labeled N-phenylpicolinium salts and phenyl-substituted picolines was developed. 相似文献
34.
High-performance liquid chromatography of human milk triacylglycerols and gas chromatography of component fatty acids 总被引:1,自引:0,他引:1
Human milk triacylglycerols were separated by high-performance liquid chromatography. A 5-μ Supelcosil LC-18 column (Supelco,
Inc., Bellefonte, PA) was used with acetone/acetonitrile (64∶36, vol/vol) as mobile phase. Triacylglycerols were tentatively
identified based on theoretical carbon number and relative retention time. Despite changes resulting from dietary fat variation,
the major component triacylglycerols were those composed of palmitic, oleic and linoleic acids. Triacylglycerols with palmitic,
stearic and oleic acids were present as minor components. Fatty acids were quantified by gas chromatography relative to an
internal standard. Ratios of n−6/n−3 fatty acids were found to be high than previously reported.
Based on a paper presented at the Symposium on Milk Lipids held at the AOCS Annual Meeting, Baltimore, MD, April 1990. 相似文献
35.
Allen Daniel N.; Strauss Gregory P.; Kemtes Karen A.; Goldstein Gerald 《Canadian Metallurgical Quarterly》2007,21(6):713
Hemispheric involvement in reasoning abilities has been debated for some time, and it remains unclear whether the right hemisphere's involvement in problem solving is modality specific or dependent on the type of spatial reasoning required. In the current study, 2 types of nonverbal reasoning abilities were examined, spatial reasoning and proportional reasoning, in 109 patients with cerebrovascular disease that was confined to either the right or the left hemisphere or was diffuse in nature. Results indicated that no lateralizing effects were present based on type of spatial reasoning. Findings are consistent with the suggestion that higher order cognitive processes involved in nonverbal abstraction and problem solving are not strongly lateralized to the right hemisphere but rather are more generally distributed throughout the cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
36.
J Randerson L Cawkwell A Jack JA Child F Lewis N Hall P Johnson P Evans S Barrans GJ Morgan 《Canadian Metallurgical Quarterly》1996,93(1):160-162
Fluorescent polymerase chain reaction (PCR) was used to assay 12 microsatellite markers (APC x 2, DCC, P53 x 2, RB1, NM23, WT1, D6S260, D6S262, D6S281 and TNFa) to look for evidence of microsatellite instability in 40 cases of follicle centre cell lymphoma (FCC). Evidence of novel alleles seen in the tumour tissue but not the normal uninvolved tissue was seen in seven cases (17%). In only two of these cases (5%) was more than one locus involved but in these cases multiple affected loci were seen (4/12 and 7/12 respectively). The detection of microsatellite instability indicates a DNA repair defect such as that which would be predicted to occur in cells with mutated mismatch repair genes, a novel finding in FCC lymphoma. 相似文献
37.
R Lewis 《Canadian Metallurgical Quarterly》1998,24(3):95-97
The management of pain in patients with burn wounds is complex and problematic. Burn-wound pain is severe, inconsistent and underestimated. Patients experience severe pain, especially during procedures, until wound healing has occurred. A multi-modality approach is needed for effective management of pain, which requires an understanding of the mechanisms of pain. Altered pharmacokinetics and pharmacodynamics in burn-wound patients makes drug actions unpredictable. Opioids alone are seldom sufficient for pain control. The multi-modality approach includes the use of opioids and non-steroidal anti-inflammatory, anxiolytic and alternative drugs. Ketamine has been found to be a useful agent for analgesia in burn-wound patients; a dose of 10 mg/kg qid per os was found to be an effective adjunct to pain therapy. 相似文献
38.
Network management in large heterogeneous communication environments requires the incorporation of more advanced tools than are currently available, especially in the area of fault management. By providing an informational infrastructure for documenting network behavior and maintenance activities, TTSs (trouble ticket systems) have provided some relief for the fault management problem. Researchers have recognized TTSs as a means for realizing more advanced functions in network management platforms to effect automatic trouble ticket generation, fault diagnostics, and the correlation of multiple views network problems and behavior. The authors describe current research trends towards understanding and implementing these advanced functions in a TTS framework 相似文献
39.
Kovacs G.T.A. Storment C.W. Halks-Miller M. Belczynski C.R. Jr. Santina C.C.D. Lewis E.R. Maluf N.I. 《IEEE transactions on bio-medical engineering》1994,41(6):567-577
A new process for the fabrication of regeneration microelectrode arrays for peripheral and cranial nerve applications is presented. This type of array is implanted between the severed ends of nerves, the axons of which regenerate through via holes in the silicon and are thereafter held fixed with respect to the microelectrodes. The process described is designed for compatibility with industry-standard CMOS or BiCMOS processes (it does not involve high-temperature process steps nor heavily-doped etch-stop layers), and provides a thin membrane for the via holes, surrounded by a thick silicon supporting rim. Many basic questions remain regarding the optimum via hole and microelectrode geometries in terms of both biological and electrical performance of the implants, and therefore passive versions were fabricated as tools for addressing these issues in on-going work. Versions of the devices were implanted in the rat peroneal nerve and in the frog auditory nerve. In both cases, regeneration was verified histologically and it was observed that the regenerated nerves had reorganized into microfascicles containing both myelinated and unmyelinated axons and corresponding to the grid pattern of the via holes. These microelectrode arrays were shown to allow the recording of action potential signals in both the peripheral and cranial nerve settings, from several microelectrodes in parallel 相似文献
40.