全文获取类型
收费全文 | 1824篇 |
免费 | 3篇 |
专业分类
化学工业 | 12篇 |
机械仪表 | 1篇 |
建筑科学 | 7篇 |
能源动力 | 3篇 |
轻工业 | 5篇 |
石油天然气 | 17篇 |
无线电 | 1篇 |
一般工业技术 | 4篇 |
冶金工业 | 1745篇 |
自动化技术 | 32篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2015年 | 1篇 |
2014年 | 9篇 |
2013年 | 5篇 |
2012年 | 4篇 |
2011年 | 2篇 |
2010年 | 6篇 |
2009年 | 5篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 6篇 |
2004年 | 3篇 |
2003年 | 16篇 |
2002年 | 7篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 54篇 |
1998年 | 522篇 |
1997年 | 291篇 |
1996年 | 226篇 |
1995年 | 110篇 |
1994年 | 98篇 |
1993年 | 105篇 |
1992年 | 11篇 |
1991年 | 30篇 |
1990年 | 32篇 |
1989年 | 23篇 |
1988年 | 37篇 |
1987年 | 22篇 |
1986年 | 22篇 |
1985年 | 13篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1978年 | 3篇 |
1977年 | 36篇 |
1976年 | 71篇 |
1966年 | 1篇 |
排序方式: 共有1827条查询结果,搜索用时 62 毫秒
991.
992.
Y Zhang O Van Reeth PC Zee JS Takahashi FW Turek 《Canadian Metallurgical Quarterly》1993,164(1-2):203-208
A mutant human lysozyme, designated as C77A-a, in which glutathione is bound to Cys95, has been shown to mimic an intermediate in the formation of a disulfide bond during folding of human (h)-lysozyme. Protein disulfide isomerase (PDI), which is believed to catalyze disulfide bond formation and associated protein folding in the endoplasmic reticulum, attacked the glutathionylated h-lysozyme C77A-a to dissociate the glutathione molecule. Structural analyses showed that the protein is folded and that the structure around the disulfide bond, buried in a hydrophobic core, between the protein and the bound glutathione is fairly rigid. Thioredoxin, which has higher reducing activity of protein disulfides than PDI, catalyzed the reduction with lower efficiency. These results strongly suggest that PDI can catalyze the disulfide formation in intermediates with compact structure like the native states in the later step of in vivo protein folding. 相似文献
993.
994.
RG Roussev CB Coulam BD Kaider M Yarkoni PC Leavis ER Barnea 《Canadian Metallurgical Quarterly》1996,2(11):883-887
Preimplantation factor (PIF) is detected in the serum of women shortly after fertilization; its origin, however, has not been established. In this study, the embryonal origin of PIF was investigated and partial characterization of the factor was carried out. Culture media from viable human 2-8-cell stage embryos and mouse 2-cell-blastocyst stage embryos were analysed using the lymphocyte/platelet binding assay (LPBA). The assay was performed by combining culture media with donor O+ type blood-derived lymphocytes/platelets, complement and an antibody against CD2. Increased autorosette formation between lymphocytes and platelets (> 9%) was an indication for the presence of PIF. In addition, the effect of platelet-activating factor (PAF) and chaperonin 10 on PIF activity was determined. Partial purification of PIF was carried out using gel filtration and reverse-phase high purification liquid chromatography (HPLC), followed by mass spectrometry. Culture media of single human viable fertilized oocytes were negative for PIF; however, the 10-fold concentrated medium was positive for PIF. In medium in which five or more mouse embryos were cultured, PIF activity was observed starting at the morula stage and was higher by the blastocyst stage. Addition of PAF or chaperonin 10 to the PIF assay did not elicit a specific effect on PIF activity. Chromatographic data suggest that PIF activity is due to low molecular weight proteins. PIF appears to be a low molecular weight protein which is derived from viable preimplantation embryos. It is different from PAF or chaperonin 10. Its final characterization will be valuable for better understanding of maternal recognition of pregnancy and implantation. 相似文献
995.
PC Freeny 《Canadian Metallurgical Quarterly》1994,29(4):373-386
The experimental work discussed here supports the hypothesis that in the pathogenesis of MG the initial and essential steps take place within the thymus. Most if not all thymuses of MG patients contain B cells capable of producing AChR specific autoantibody along with appropriate stroma elements. Hyperplastic thymuses characteristically contain germinal centers with cellular complexes of AChR-producing MC and surrounding interdigitating dendritic cells. In thymomas, the source of the myasthenogenic autoantigen is less obvious. There are data suggesting that thymoma epithelium expresses a protein sharing certain peptide epitopes with the AChR alpha chain, although there is no further molecular similarity. A unique type of 'molecular self-mimicry' cold be involved in the initiation of thymoma-associated MG. 相似文献
996.
TS Yeh CR Wang SH Huang SF Huang PC Yang CY Chuang 《Canadian Metallurgical Quarterly》1993,92(2):192-194
This paper explores nursing's current fascination with defining and exploring the term 'caring'. Fear of caring is proposed as the reason for this fascination. Factors at the root of this fear are identified and an expanded definition of caring (one which arises from the dispelling of such fear) is proposed. This expanded definition is given a new label--loving. For, as this author contends, has not loving always been at the heart of nursing? 相似文献
997.
998.
999.
1000.
PC Jobe PK Mishra RA Browning C Wang LE Adams-Curtis KH Ko JW Dailey 《Canadian Metallurgical Quarterly》1994,35(5-6):493-504
The genetically epilepsy-prone rat (GEPR) has central nervous system noradrenergic deficits as compared to normal rats. It is possible that these deficits contribute to seizure predisposition because they are exhibited by seizure-naive as well as by seizure-experienced GEPRs. On the basis of pharmacological studies, it is hypothesized that there is an inverse relation between seizure predisposition and levels of noradrenergic activity in brain. Neurochemical studies indicate that deficits exist in areas innervated by both the locus ceruleus and the lateral tegmental noradrenergic systems. These deficits exist in GEPRs without seizure experience and are more pronounced in the severe seizure strain as compared to the moderate seizure strain. We review eight experimental steps undertaken to identify more precisely the anatomical location of noradrenergic determinants of seizure predisposition. These steps illustrate the theoretical bases for the studies and describe the specific experiments completed. Evidence supports the hypothesis that noradrenergic deficits in the superior colliculus and/or ventrally adjacent regions are determinants of seizure predisposition. 相似文献