全文获取类型
收费全文 | 1218篇 |
免费 | 4篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 38篇 |
金属工艺 | 5篇 |
建筑科学 | 3篇 |
能源动力 | 2篇 |
轻工业 | 5篇 |
水利工程 | 5篇 |
石油天然气 | 9篇 |
无线电 | 7篇 |
一般工业技术 | 37篇 |
冶金工业 | 1023篇 |
原子能技术 | 1篇 |
自动化技术 | 78篇 |
出版年
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 10篇 |
2012年 | 7篇 |
2011年 | 9篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 10篇 |
2007年 | 9篇 |
2006年 | 5篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 10篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 40篇 |
1998年 | 326篇 |
1997年 | 197篇 |
1996年 | 100篇 |
1995年 | 73篇 |
1994年 | 48篇 |
1993年 | 70篇 |
1992年 | 8篇 |
1991年 | 20篇 |
1990年 | 16篇 |
1989年 | 13篇 |
1988年 | 17篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1978年 | 11篇 |
1977年 | 23篇 |
1976年 | 49篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1222条查询结果,搜索用时 51 毫秒
91.
92.
This paper argues that intermediation is both a valuable form of occupational self-organization for professional artists and a political act of embedding with socio-spatial ramifications at different local, urban, and global scales. A case study of events organized in Berlin by the interdisciplinary cultural centre Zentrum für Kunst und Urbanistik demonstrates how artists strategically practice intermediation as modes of autopoietic and dissipative self-organization and as an interscalar survival strategy. These artist intermediaries add improvisational flexibility to the state’s understanding of Verstetigung (sustainable anchoring that fosters a reliable relationship between urban policymakers and cultural producers) and challenge neoliberal urban development logics that instrumentalize creativity. 相似文献
93.
Simultaneous interphase mass transfer and a zero–order reaction is described by the film model of mass transfer. The analysis leads to the conclusion that three regimes of the process need to be considered. At low rates of absorption the reaction goes to completion in the film, and at higher rates it goes to completion in the bulk and proceeds there at zero apparent concentration of the reactant. At still higher rates of absorption the reaction does not go to completion and the reactant is present also in the bulk in appreciable concentration. Design procedures based on the results obtained are discussed for a well–mixed CSTR and for a column with con–tinuous change. 相似文献
94.
SF Quan BV Howard C Iber JP Kiley FJ Nieto GT O'Connor DM Rapoport S Redline J Robbins JM Samet PW Wahl 《Canadian Metallurgical Quarterly》1997,20(12):1077-1085
The Sleep Heart Health Study (SHHS) is a prospective cohort study designed to investigate obstructive sleep apnea (OSA) and other sleep-disordered breathing (SDB) as risk factors for the development of cardiovascular disease. The study is designed to enroll 6,600 adult participants aged 40 years and older who will undergo a home polysomnogram to assess the presence of OSA and other SDB. Participants in SHHS have been recruited from cohort studies in progress. Therefore, SHHS adds the assessment of OSA to the protocols of these studies and will use already collected data on the principal risk factors for cardiovascular disease as well as follow-up and outcome information pertaining to cardiovascular disease. Parent cohort studies and recruitment targets for these cohorts are the following: Atherosclerosis Risk in Communities Study (1,750 participants), Cardiovascular Health Study (1,350 participants), Framingham Heart Study (1,000 participants), Strong Heart Study (600 participants), New York Hypertension Cohorts (1,000 participants), and Tucson Epidemiologic Study of Airways Obstructive Diseases and the Health and Environment Study (900 participants). As part of the parent study follow-up procedures, participants will be surveyed at periodic intervals for the incidence and recurrence of cardiovascular disease events. The study provides sufficient statistical power for assessing OSA and other SDB as risk factors for major cardiovascular events, including myocardial infarction and stroke. 相似文献
95.
SF Zarbock 《Canadian Metallurgical Quarterly》1997,2(6):288-9, 294
In recent years, home visitation services have been widely promoted as a means of preventing health and developmental problems in children from vulnerable families. The U.S. Advisory Board of Child Abuse and Neglect, for example, recommended that home visitation services be made available to all parents of newborns to prevent child abuse and neglect. 相似文献
96.
97.
98.
WA Paxton R Liu S Kang L Wu TR Gingeras NR Landau CR Mackay RA Koup 《Canadian Metallurgical Quarterly》1998,244(1):66-73
Escherichia coli leader peptidase, an integral membrane protein, is responsible for the cleavage of the signal sequence of many exported proteins. Recent studies suggest that it is a novel serine protease that utilizes a serine-lysine catalytic dyad. In an effort to further understand the mechanism of this enzyme, an internally quenched fluorescent peptide substrate incorporating the leader peptidase cleavage site of maltose binding protein signal peptide, Y(NO2)-F-S-A-S-A-L-A-K-I-K(Abz) (anthraniloyl), was designed and synthesized. In the intact peptide, the fluorescence of the anthraniloyl group is quenched by the 3-nitrotyrosine. This quenched fluorescence is liberated upon cleavage of the peptide by the leader peptidase, resulting in increased fluorescence that could then be monitored fluorometrically. The designed substrate can be cleaved effectively by E. coli leader peptidase as detected by both HPLC and fluorescent spectroscopy. Mass spectra of cleavage products demonstrated that the cleavage occurs at the predicted site (A-K). The cleavage of the peptide substrate has a linear dependence on the enzyme concentration (0.1 to 1.9 microM) and the kcat/K(m) was calculated to be 71.1 M-1 s-1. These data are comparable with the unmodified peptide substrate. This report represents the first direct continuous assay based on fluorescence resonance energy transfer for E. coli leader peptidase. 相似文献
99.
SF Nielsen SB Christensen G Cruciani A Kharazmi T Liljefors 《Canadian Metallurgical Quarterly》1998,41(24):4819-4832
A large number of substituted chalcones have been synthesized and tested for antileishmanial and lymphocyte-suppressing activities. A subset of the chalcones was designed by using statistical methods. 3D-QSAR analyses using 67 (antileishmanial activity) and 63 (lymphocyte-suppressing activity) of the compounds for the training sets and 9 compounds as an external validation set were performed by using the GRID/GOLPE methodology. The Smart Region Definition procedure with subsequent region selection as implemented in GOLPE reduced the number of variables to approximately 1300 yielding 3D-QSAR models of high quality (lymphocyte-suppressing model, R2 = 0. 90, Q2 = 0.80; antileishmanial model, R2 = 0.73, Q2 = 0.63). The coefficient plots indicate that steric interactions between the chalcones and the target are of major importance for the potencies of the compounds. A comparison of the coefficient plots for the antileishmanial effect and the lymphocyte-suppressing activity discloses significant differences which should make it possible to design chalcones having a high antileishmanial activity without suppressing the proliferation of lymphocytes. 相似文献
100.
Antimicrobial therapy can be a confounding factor in the diagnosis of urinary tract infection and is not always reported to laboratories by physicians. We developed a microbiologic assay for screening urine specimens for antimicrobial agents. Bacillus stearothermophilus was used as the indicator bacteria. A total of 1,921 urine specimens from three hospitals in Taiwan were screened using this assay. Of the samples assayed, 1,293 were positive for antimicrobial agents. Agreement between information provided by physicians and laboratory findings was 68.5% (419/612). In the presence of antimicrobial agents in the urine samples, the isolation of yeasts and Pseudomonas aeruginosa increased dramatically, from 4.5 to 19.5% and 4.2 to 13.2%, respectively. Additionally, Escherichia coli was more resistant to gentamicin (75.3% vs 48.7%, p < 0.0001), norfloxacin (85.2% vs 64.6%, p = 0.0006) and co-trimoxazole (58.5% vs 35.5%, p = 0.0018). In view of the high rate of occurrence of antimicrobial agents in urine specimens and the lack of information provided by most physicians to laboratories, a screening method to detect the presence (or absence) of antimicrobials in urine specimens may be a useful tool particularly in areas such as Taiwan where antimicrobial agents are commonly abused. 相似文献