全文获取类型
收费全文 | 436篇 |
免费 | 0篇 |
国内免费 | 3篇 |
专业分类
化学工业 | 18篇 |
金属工艺 | 6篇 |
建筑科学 | 1篇 |
矿业工程 | 1篇 |
轻工业 | 16篇 |
石油天然气 | 1篇 |
无线电 | 14篇 |
一般工业技术 | 10篇 |
冶金工业 | 358篇 |
原子能技术 | 6篇 |
自动化技术 | 8篇 |
出版年
2016年 | 1篇 |
2014年 | 1篇 |
2013年 | 4篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 7篇 |
2000年 | 1篇 |
1999年 | 12篇 |
1998年 | 116篇 |
1997年 | 70篇 |
1996年 | 44篇 |
1995年 | 30篇 |
1994年 | 31篇 |
1993年 | 30篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 6篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1976年 | 7篇 |
1968年 | 1篇 |
1964年 | 1篇 |
1947年 | 1篇 |
1945年 | 1篇 |
1940年 | 1篇 |
排序方式: 共有439条查询结果,搜索用时 15 毫秒
131.
132.
YL Yang L Guo S Xu CA Holland T Kitamura K Hunter JM Cunningham 《Canadian Metallurgical Quarterly》1999,21(2):216-219
The onset of leukaemia caused by type C retroviruses (MLV) in mice is accelerated by the emergence of recombinant polytropic or mink cell focus-forming (MCF) viruses. Susceptibility to infection by polytropic/MCF and also by closely related xenotropic MLV has been mapped to Rmc1 on mouse chromosome 1 (refs 5-7). To identify this gene, we introduced an expression cDNA library prepared from mouse NIH3T3 fibroblasts into nonpermissive hamster cells and screened these cells for acquired susceptibility to MCF viruses encoding beta-galactosidase and G418 resistance. From hamster cell clones identified in the screen, we recovered a mouse cDNA that maps to Rmc1 and confers MCF MLV infection when expressed in nonpermissive cell lines. It encodes a membrane protein related to Syg1p (suppressor of yeast G alpha deletion; ref. 8). The receptor-binding domain of the MCF MLV envelope protein binds specifically to Xenopus laevis oocytes that express mouse Syg1, suggesting it functions as a receptor that mediates virus entry. We also obtained the cDNA encoding human SYG1. When expressed in hamster cells, it establishes infectivity by MCF MLV as well as xenotropic MLV, which do not infect laboratory mice. 相似文献
133.
134.
R Faghih PA Lartey HN Nellans L Seif C Burnell-Curty LL Klein P Thomas A Petersen A Borre T Pagano KH Kim M Heindel YL Bennani JJ Plattner 《Canadian Metallurgical Quarterly》1998,41(18):3402-3408
In our quest toward the discovery of highly potent and acid-stable motilides, novel 4"-deoxy derivatives of 9-deoxo-6, 9-epoxyerythromycin were designed, synthesized, and evaluated for their gastrointestinal prokinetic activities. These compounds, in their 9R configuration, were more potent than their 6,9-enol ether homologues in inducing well-coordinated smooth muscle contractions in an in vitro rabbit duodenal assay: e.g., (9R), (8S)-9-deoxo-4"-deoxy-3'-N-desmethyl-3'-N-ethyl-6, 9-epoxyerythromycin A (10) and (9R), (8S)-9-deoxo-4"-deoxy-3'-N-desmethyl-3'-N-ethanol-6, 9-epoxyerythromycin A (15) had a pED50 of 8.54 and 8.11 compared to a pED50 of 7.22 for compound 2 (ABT-229). Reduction of the 6,9-enol ether, which was aimed at improving the acid stability, afforded the most stable motilides to date with t1/2 of 5.5 h for 10 and 15. Compounds 10 and 15 bind specifically to rabbit antral smooth muscle motilin receptors with pIC50 values of 8.52 and 8.70. 相似文献
135.
136.
Both the Biosite Triage (Biosite Diagnostics, San Diego, CA) method and the Du Pont aca (Du Pont Company, Wilmington, DE) method give qualitative tricyclic antidepressant (TCA) results to aid in the diagnosis of a TCA overdose. The Triage method uses urine samples and the aca uses serum samples. Although the cutoff values vary considerably between the two methods, the Triage results agreed well with the aca results. The Triage test has an advantage in instrument maintenance and time savings, allowing a reduction in turn-around time for our emergency department. Both urine and serum samples were obtained from 44 patients who were admitted to the emergency department with a diagnosis of "possible tricyclic overdose." Discrepancies between the two methods were resolved by thin layer chromatography (Toxi-Lab, Ansys, Inc, Irvine, CA). Both methods were in agreement with the exception of five patients' samples. In this study, the Triage method allowed for detection of TCA using urine that is simple for the user and yielded higher sensitivity and specificity results compared with the Du Pont aca method. 相似文献
137.
YL. Chen 《金属学报(英文版)》1997,10(4):311-317
1.IntroductionPdalloysareausefulsubjectforrelatingthermodynamicpropertieswithelectronicandelasticquantitiesofthecomponents.ThethermodynamicfunctionsofanumberofinterstitialandsubstitutionalPdalloysexhibitanalogouscharacteristicsandmaybeinterpretedinthesamemanner-Twoeffectswerediscussedtoaccountforthenon-idealproperties.An"elastic"effectisassociatedwiththelatticedistortionbroughtaboutbythedissolvedparticles.Theenergyofelasticstrainfieldsoftwoseparatesoluteatomsischangediftheparticlesenteradjace… 相似文献
138.
The 2002 NAHM's Dairy Survey indicated that 87.2% of dairy farms in the United States feed waste milk to their neonatal calves. Although cost-effective, this practice can lead to increased calf morbidity and mortality due to ingestion of pathogenic agents. In an effort to reduce the risk of infection, dairy producers are implementing on-farm pasteurization of the waste milk as a control procedure before feeding the milk to calves. In the present study, the efficacy of a commercial high-temperature, short-time (HTST) on-farm pasteurizer unit to destroy Mycobacterium paratuberculosis, Salmonella enterica spp., and Mycoplasma spp. in raw milk was evaluated. Replicate experiments were run for 3 isolates of M. paratuberculosis, 3 serovars of Salmonella (derby, dublin, typhimurium); and 4 species of Mycoplasma (bovis, californicum, canadense, serogroup 7) at 2 different levels of experimental inoculation. In addition, HTST pasteurization experiments were performed on colostrum experimentally inoculated with M. paratuberculosis. After culture of the pasteurized milk samples, no viable M. paratuberculosis, Salmonella, or Mycoplasma were recovered, regardless of species, strain, or isolate. Pasteurization of colostrum was also effective in the destruction of M. paratuberculosis but resulted in an average 25% reduction in colostral immunoglobulin. These results suggest that HTST pasteurization is effective in generating a safer product to feed to young calves. 相似文献
139.
Human papillomaviruses were detected by an in vitro enzymatic DNA amplification method in cells obtained from vulvar swabs of 9 of 61 (14.8%) young women without prior experience of sexual intercourse and in 7 of 57 (12.3%) young women with prior experience. The prevalence of human papillomavirus DNA in these two groups of women was not significantly different (x2 = 0.16, p > 0.5; 95% confidence interval -0.165 to 0.215). These results suggest that genital human papillomavirus is not sexually transmitted in all cases and that it may be acquired by modes other than sexual contact. 相似文献
140.
The 21 S complex of enzymes for DNA synthesis in the combined low salt nuclear extract-post microsomal supernatant from HeLa cells [Malkas et al. (1990) Biochemistry 29:6362-6374] was purified by poly (ethylene glycol) precipitation, Q-Sepharose chromatography, Mono Q Fast Protein Liquid Chromatography (FPLC), and velocity gradient centrifugation. The procedure gives purified enzyme complex at a yield of 45%. The 21 S enzyme complex remains intact and functional in the replication of simian virus 40 DNA throughout the purification. Sedimentation analysis showed that the 21 S enzyme complex exists in the crude HeLa cell extract and that simian virus 40 in vitro DNA replication activity in the cell extract resides exclusively with the 21 S complex. The results of enzyme and immunological analysis indicate that DNA polymerase alpha-primase, a 3',5' exonuclease, DNA ligase I, RNase H, and topoisomerase I are associated with the purified enzyme complex. Denaturing polyacrylamide gel electrophoresis of the purified enzyme complex showed the presence of about 30 polypeptides in the size range of 300 to 15 kDa. Immunofluorescent imaging analysis, with antibodies to DNA polymerase alpha,beta and DNA ligase I, showed that polymerase alpha and DNA ligase I are localized to granular-like foci within the nucleus during S-phase. In contrast, DNA polymerase beta, which is not associated with the 21 S complex, is diffusely distributed throughout the nucleoplasm. 相似文献