全文获取类型
收费全文 | 3249篇 |
免费 | 0篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 20篇 |
金属工艺 | 4篇 |
机械仪表 | 2篇 |
建筑科学 | 2篇 |
矿业工程 | 2篇 |
能源动力 | 2篇 |
轻工业 | 6篇 |
石油天然气 | 3篇 |
无线电 | 1篇 |
一般工业技术 | 8篇 |
冶金工业 | 3184篇 |
原子能技术 | 5篇 |
自动化技术 | 8篇 |
出版年
2020年 | 2篇 |
2018年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2008年 | 1篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 70篇 |
1998年 | 924篇 |
1997年 | 541篇 |
1996年 | 391篇 |
1995年 | 235篇 |
1994年 | 164篇 |
1993年 | 183篇 |
1992年 | 20篇 |
1991年 | 33篇 |
1990年 | 29篇 |
1989年 | 30篇 |
1988年 | 25篇 |
1987年 | 19篇 |
1986年 | 18篇 |
1985年 | 20篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 19篇 |
1981年 | 25篇 |
1980年 | 34篇 |
1979年 | 5篇 |
1978年 | 12篇 |
1977年 | 131篇 |
1976年 | 258篇 |
1975年 | 11篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有3249条查询结果,搜索用时 0 毫秒
991.
992.
993.
RJ Sherertz WA Carruth AA Hampton MP Byron DD Solomon 《Canadian Metallurgical Quarterly》1993,167(1):98-106
Vascular catheters coated with antiinfective compounds were evaluated as to their ability to prevent Staphylococcus aureus catheter infection in a rabbit model. Zones of inhibition of agar surface-plated S. aureus demonstrated the following hierarchy: dicloxacillin and clindamycin were each better than fusidic acid or chlorhexidine, which were better than ciprofloxacin, cefotaxime, or cefuroxime. In vivo half-lives of inhibitory activity for clindamycin and dicloxacillin were 5.6 and 17.7 h, respectively, with apparent first-order kinetics. Chlorhexidine disappeared in vivo with apparent two-compartment kinetics: first-compartment t1/2, 16.8 h; second-compartment t1/2, 115.6 h. In a rabbit model, dicloxacillin, clindamycin, fusidic acid, and chlorhexidine decreased the risk of infection compared with uncoated control catheters (P < .05). For dicloxacillin, clindamycin, and chlorhexidine, this was true even if the S. aureus inoculation was delayed 48 or 96 h after catheter implantation. These data suggest that vascular catheters with antiinfective coatings should be investigated further in hospitalized patients. 相似文献
994.
995.
996.
997.
AIMS: To determine levels of injecting drug use and sexual risk behaviours in injecting drug users during and immediately following imprisonment in The Netherlands. DESIGN, SETTING AND PARTICIPANTS: Cross-sectional survey of drug injectors attending methadone clinics, a sexually transmitted disease clinic and a central research site in Amsterdam. The mean age of the 188 participants was 35 years, 78% were male and 34% had HIV antibodies. MEASUREMENTS: Self-reported drug use and sexual behaviours during the last period of imprisonment in Dutch prisons within the previous 3 years and injecting drug use in the week following release from prison. FINDINGS: A period of imprisonment in the preceding 3 years was reported by 188 (41%) of 463 interviewed drug injectors. The mean duration of last imprisonment was 3.6 months. Any use of cannabis, heroin or cocaine during imprisonment was reported by 55%, 37% and 20%, respectively. Five injectors (3%) admitted to having injected in prison, but no sharing of needles and syringes was reported. Vaginal or anal sex was reported by two (1%) of the men and none of the women. Relapse to drug injecting during the week following release from prison was reported by 78/186 (42%) participants, in most cases (34%) at the very first day of release. Drug use behaviours during imprisonment were similar for those who were designated current injectors at the time of imprisonment and those who were not, but injecting in the first week following release from prison was far higher among 'current' injectors (63%) than among those who were not (11%). CONCLUSIONS: Contrary to findings from other countries, low levels of HIV risk behaviours occur among imprisoned drug injectors in The Netherlands. Intra-prison HIV preventive measures should be considered taking into account the nationally, regionally or locally varying conditions within the existing prisons. 相似文献
998.
FJ Frost AA de la Cruz DM Moss M Curry RL Calderon 《Canadian Metallurgical Quarterly》1998,121(1):205-211
A seroprevalence survey was conducted using ELISA and Western blot (WB) assays for antibody to three Cryptosporidium antigens on 380 blood donors in Jackson County, Oregon. The purpose was to determine if either assay could detect serological evidence of an outbreak which occurred in Talent, Oregon 6 months earlier. The ELISA, which tested for combined IgG, IgA and IgM, and the WB, which tested separately for IgG and IgA, detected an almost twofold increase in serological response for persons who consumed Talent drinking water during the previous 11 months. The increases, however, were statistically significant (P < 0.05) only for the WB. The identification of serological evidence of infection, using sera collected 6 months after the end of the outbreak in a population not selected because of cryptosporidiosis-like illness, suggests that assays of Cryptosporidium-specific IgG and IgA may assist in estimating the magnitude of asymptomatic infections in the population. 相似文献
999.
1000.
AP Soler GD Harner KA Knudsen FX McBrearty E Grujic H Salazar AC Han AA Keshgegian 《Canadian Metallurgical Quarterly》1997,151(2):471-478
PURPOSE: To evaluate the efficacy of dynamic computed tomography (CT) for differentiating benign from malignant solitary pulmonary nodules (SPNs). MATERIALS AND METHODS: Sixty-five patients with noncalcified SPNs (diameter, < or = 30 mm; 42 malignant, 16 benign, seven inflammatory) underwent single-location dynamic contrast material-enhanced (100 mL, 4 mL/sec) serial CT. Peak height of time-attenuation curves and ratio of peak height of the SPN to that of the aorta were measured. Precontrast attenuation and enhancement pattern were recorded. Perfusion was calculated from the maximum gradient of the time-attenuation curve and the peak height of the aorta. RESULTS: Peak heights of malignant (41.9 HU +/- 2.8) and inflammatory (43.6 HU +/- 7.7) SPNs were significantly higher than that (13.4 HU +/- 2.2) of benign SPNs (P < .001; P < .01). SPN-to-aorta ratios in malignant and inflammatory SPNs were significantly higher than that in benign SPNs (P < .001, P < .05). No statistically significant differences in the peak height and SPN-to-aorta ratio were found between malignant and inflammatory SPNs. Precontrast attenuation of inflammatory SPNs was lower than that of malignant SPNs (P < .05). Perfusion values in malignant and inflammatory SPNs were significantly higher than that of the benign SPNs (P < .01). CONCLUSION: Dynamic CT provides quantitative information about blood flow patterns of SPNs and is an applicable diagnostic method for differentiating SPNs. 相似文献