全文获取类型
收费全文 | 1110篇 |
免费 | 5篇 |
专业分类
电工技术 | 11篇 |
化学工业 | 47篇 |
金属工艺 | 7篇 |
机械仪表 | 6篇 |
建筑科学 | 5篇 |
矿业工程 | 1篇 |
能源动力 | 11篇 |
轻工业 | 21篇 |
石油天然气 | 1篇 |
无线电 | 19篇 |
一般工业技术 | 20篇 |
冶金工业 | 933篇 |
原子能技术 | 8篇 |
自动化技术 | 25篇 |
出版年
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 4篇 |
2011年 | 8篇 |
2010年 | 12篇 |
2009年 | 9篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2005年 | 7篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2002年 | 3篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 37篇 |
1998年 | 247篇 |
1997年 | 149篇 |
1996年 | 119篇 |
1995年 | 51篇 |
1994年 | 51篇 |
1993年 | 61篇 |
1992年 | 8篇 |
1991年 | 10篇 |
1990年 | 12篇 |
1989年 | 20篇 |
1988年 | 12篇 |
1987年 | 20篇 |
1986年 | 14篇 |
1985年 | 15篇 |
1984年 | 5篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 16篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 29篇 |
1976年 | 65篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1971年 | 4篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1963年 | 5篇 |
1962年 | 3篇 |
1961年 | 3篇 |
1955年 | 2篇 |
排序方式: 共有1115条查询结果,搜索用时 31 毫秒
21.
P O'Hara JE Connett WW Lee M Nides R Murray R Wise 《Canadian Metallurgical Quarterly》1998,148(9):821-830
The authors examine weight gains associated with smoking cessation in the Lung Health Study (1986-1994) over a 5-year follow-up period. A cohort of 5,887 male and female smokers in the United States and Canada, aged 35-60 years, were randomized to either smoking intervention or usual care. Among participants who achieved sustained quitting for 5 years, women gained a mean of 5.2 (standard error, 5.0) kg in year 1 and a mean of 3.4 (standard error, 5.5) kg in years 1-5. Men gained a mean of 4.9 (standard error, 4.9) kg in year 1 and a mean of 2.6 (standard error, 5.8) kg in years 1-5. In regression analyses, smoking-change variables were the most potent predictors of weight change. Participants going from smoking to quit-smoking in a given year had mean weight gains of 2.95 kg/year (3.61%) in men and 3.09 kg/year (4.69%) in women. Over 5 years, 33% of sustained quitters gained > or = 10 kg compared with 6% of continuing smokers. Also among sustained quitters, 7.6% of men and 19.1% of women gained > or = 20% of baseline weight; 60% of the gain occurred in year 1, although significant weight gains continued through year 5. The average gains and the high proportions of sustained and intermittent quitters who gained excessive weight suggest the need for more effective early interventions that address both smoking cessation and weight control. 相似文献
22.
Electron microscopy of toad (Bufo marinus) muscle fixed without relaxing after a single eccentric contraction at muscle lengths greater than optimum showed over-stretched half-sarcomeres in sufficient numbers to account for more than half of the imposed stretch. Such sarcomeres were absent in another muscle fixed without relaxing after an isometric contraction at the same length and largely absent in a third muscle that underwent eccentric contraction at muscle lengths less than optimum. This provides direct evidence in support of the hypothesis that lengthening of muscles at long length involves lengthening of a few half sarcomeres to beyond filament overlap, while most half sarcomeres are extended much less than in proportion to muscle extension. 相似文献
23.
KJ Barakat K Cheng WW Chan BS Butler TM Jacks KD Schleim DF Hora GJ Hickey RG Smith AA Patchett RP Nargund 《Canadian Metallurgical Quarterly》1998,8(11):1431-1436
A new class of potent, orally active phenyl piperazine-based GH secretagogues have been discovered from attempts to mimic the arrangement of the phenyl substituent in the spiroindanyl piperidine and spiroindoline sulfonamide privileged structures of 4 and 1, respectively. The best of these compounds, 18 (EC50 = 2.8 nM) is nearly as potent as MK-0677 for releasing GH from rat pituitary cells. 相似文献
24.
Evaluating behavioral interventions for HIV prevention 总被引:1,自引:0,他引:1
WW Darrow 《Canadian Metallurgical Quarterly》1996,10(3):346-348
We report a case of primary amyloidosis affecting the kidney and presenting as a renal infarction on computed tomography and ultrasound examination. To our knowledge, it is the first case in the radio-logical literature with these imaging characteristics. 相似文献
25.
The ever-increasing number of proteins identified as belonging to the family of small heat-shock proteins (shsps) and alpha-crystallins enables us to reassess the phylogeny of this ubiquitous protein family. While the prokaryotic and fungal representatives are not properly resolved, most of the plant and animal shsps and related proteins are clearly grouped in distinct clades, reflecting a history of repeated gene duplications. The members of the shsp family are characterized by the presence of a conserved homologous "alpha-crystallin domain," which sometimes is present in duplicate. Predictions are made of secondary structure and solvent accessibility of this domain, which together with hydropathy profiles and intron positions support the presence of two similar hydrophobic beta-sheet-rich motifs, connected by a hydrophilic alpha-helical region. Together with an overview of the newly characterized members of the shsp family, these data help to define this family as being involved as stable structural proteins and as molecular chaperones during normal development and induced under pathological and stressful conditions. 相似文献
26.
A new experimental model of a vascular carrier to prefabricate a "secondary" island flap, the popliteal musculovascular pedicle, was developed in the rat. Using quantitative skin-surface fluorometry 30 minutes after sodium fluorescein injection and a flap survival area in the prefabricated 8 x 2.5-cm abdominal composite island flap, we compared the revascularization ability of our muscular carrier to nonrevascularized controls: the skeletonized arteriovenous pedicle and the fasciovascular pedicle. The free composite graft with no vascular carrier exhibited near-total necrosis. The skeletonized vascular pedicle demonstrated 15.2% +/- 7.8% perfusion of normal skin on dye fluorescence index measurements and 50% flap survival. The fasciovascular pedicle exhibited better revascularization, with a dye fluorescence index of 36.2 +/- 15.5 (p < 0.01) and 90% +/- 10% flap survival (p < 0.001). India ink injection study and histological examination of our model provided visual evidence of revascularization from the musculovascular pedicle, along with preservation of the carrier's muscular architecture. The musculovascular pedicle is a reliable carrier for making new, vascularized composite flaps. 相似文献
27.
Sphingolipid metabolism and cell growth regulation 总被引:2,自引:0,他引:2
28.
One of the problems with insider threat research is the lack of a complete 360° view of an insider threat dataset due to inadequate experimental design. This has prevented us from modeling a computational system to protect against insider threat situations. This paper provides a contemporary methodological approach for using online games to simulate insider betrayal for predictive behavioral research. The Leader’s Dilemma Game simulates an insider betrayal scenario for analyzing organizational trust relationships, providing an opportunity to examine the trustworthiness of focal individuals, as measured by humans as sensors engaging in computer-mediated communication. This experimental design provides a window into trustworthiness attribution that can generate a rigorous and relevant behavioral dataset, and contributes to building a cyber laboratory that advances future insider threat study. 相似文献
29.
DW Morck JK Merrill BE Thorlakson ME Olson LV Tonkinson JW Costerton 《Canadian Metallurgical Quarterly》1993,202(2):273-277
The prophylactic administration of injectable tilmicosin for pneumonia in weaned beef calves was investigated in 1,806 animals. Comparisons were made among calves receiving an "on-arrival" injection of tilmicosin, calves receiving a single injection of long-acting oxytetracycline, and calves receiving no prophylaxis. Morbidity and mortality attributable to pneumonia, morbidity and mortality attributable to all causes, and case fatality were significantly lower in the group of calves that received tilmicosin, compared with calves that received long-acting oxytetracycline and calves that received no prophylactic antibiotic. Mean time to initial pneumonia treatment was significantly extended in calves that received prophylaxis, compared with those that received no antibiotic on arrival at the feedlot. Calves that received tilmicosin gained significantly more weight than calves that received oxytetracycline. Calves that were not treated for pneumonia during the trial period gained significantly more weight than did those calves that were treated for pneumonia regardless of experimental group. The majority of mortalities were attributable to fibrinous pneumonia (31/34). Important bacterial isolates (Pasteurella spp, Haemophilus somnus, Actinomyces pyogenes) obtained at necropsy did not have resistance to tilmicosin in association with administration of tilmicosin as prophylaxis for pneumonia. However, bacterial resistance to trimethoprim/sulfonamide and to oxytetracycline were commonly found in these postmortem isolates. 相似文献
30.
This paper describes the implementation and evaluation of a nonsanction seat belt law enforcement program in two experimental communities of contrasting size in a state with a mandatory belt law. The main ingredients of the program were seat belt "salutes," public information and education, and limited use of inexpensive economic incentives. Driver shoulder belt use data collected before, during, and after the experimental programs, compared to similar data collected in a comparison community, showed the approach to be effective. While standard seat belt enforcement activities without incentives have been shown to be effective, many police departments, especially in smaller communities, are reluctant to make wholesale increases in seat belt citations. Although requiring some additional level of manpower and resources, a nonsanction approach to seat belt law enforcement can provide an alternate way of increasing belt use in these communities. 相似文献