全文获取类型
收费全文 | 1867篇 |
免费 | 15篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 25篇 |
金属工艺 | 2篇 |
机械仪表 | 2篇 |
建筑科学 | 1篇 |
能源动力 | 3篇 |
轻工业 | 36篇 |
石油天然气 | 2篇 |
无线电 | 7篇 |
一般工业技术 | 18篇 |
冶金工业 | 1777篇 |
自动化技术 | 9篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 8篇 |
2013年 | 7篇 |
2012年 | 3篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 5篇 |
2008年 | 5篇 |
2007年 | 4篇 |
2006年 | 1篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 72篇 |
1998年 | 609篇 |
1997年 | 345篇 |
1996年 | 207篇 |
1995年 | 114篇 |
1994年 | 73篇 |
1993年 | 124篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 15篇 |
1989年 | 17篇 |
1988年 | 11篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 12篇 |
1980年 | 16篇 |
1978年 | 4篇 |
1977年 | 27篇 |
1976年 | 73篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1883条查询结果,搜索用时 15 毫秒
21.
ME Hoatlin FE Ferro RW Geib MT Fox SL Kozak D Kabat 《Canadian Metallurgical Quarterly》1995,69(2):856-863
Although the Friend virus-encoded membrane glycoprotein (gp55) activates erythropoietin receptors (EpoR) to cause erythroblastosis only in certain inbred strains of mice but not in other species, mutant viruses can overcome aspects of mouse resistance. Thus, mice homozygous for the resistance allele of the Fv-2 gene are unaffected by gp55 but are susceptible to mutant glycoproteins that have partial deletions in their ecotropic domains. These and other results have suggested that proteins coded for by polymorphic Fv-2 alleles might directly or indirectly interact with EpoR and that changes in gp55 can overcome this defense. A new viral mutant with an exceptionally large deletion in its ecotropic domain is now also shown to overcome Fv-2rr resistance. In all cases, the glycoproteins that activate EpoR are processed to cell surfaces as disulfide-bonded dimers. To initiate analysis of nonmurine resistances, we expressed human EpoR and mouse EpoR in the interleukin 3-dependent mouse cell line BaF3 and compared the abilities of Friend virus-encoded glycoproteins to convert these cells to growth factor independence. Human EpoR was activated in these cells by erythropoietin but was resistant to gp55. However, human EpoR was efficiently activated in these cells by the same viral mutants that overcome Fv-2rr resistance in mice. By construction and analysis of human-mouse EpoR chimeras, we obtained evidence that the cytosolic domain of human EpoR contributes to its resistance to gp55 and that this resistance is mediated by accessory cellular factors. Aspects of host resistance in both murine and nonmurine species are targeted specifically against the ecotropic domain of gp55. 相似文献
22.
23.
C Gay H Tronchon P Divry G Teyssier MT Freycon F Freycon 《Canadian Metallurgical Quarterly》1993,48(12):894-897
The authors report two cases of citrullinemia in siblings which add to 68 observations from the literature. They overview the clinical presentation, diagnosis and therapeutic management of the disease. The prognosis of severe neonatal form remains poor but an early adequate management may contribute to an acceptable outcome. 相似文献
24.
25.
MT Massie MJ Rohrer JA Leppo BS Cutler 《Canadian Metallurgical Quarterly》1997,25(6):975-82; discussion 982-3
PURPOSE: Because dipyridamole thallium (DT) scanning is a useful predictor of perioperative cardiac events, a positive results of a DT scan is frequently the basis for performing more invasive cardiac evaluation and for consideration for performing coronary revascularization procedures before performing peripheral vascular surgery. The rationale for this approach has been that the treatment of anatomically significant coronary artery disease would lower the risk of performing a subsequent vascular operation. However, the benefit of performing aggressive diagnostic and therapeutic cardiac procedures in such patients remains unproved. To examine this issue, data from patients who underwent coronary angiography because of thallium redistribution were compared with data from matched control subjects who underwent peripheral vascular operations without further cardiac evaluation. METHODS: The medical records of 70 consecutive patients who underwent coronary angiography because of the presence of two or more segments of redistribution on DT scan were reviewed and compared with 70 other patients matched with respect to age, gender, peripheral vascular operation, and number of segments of redistribution on DT scan who did not undergo additional cardiac evaluation. RESULTS: DT scans were performed on 934 preoperative peripheral vascular surgery patients to help in the assessment of operative risk. Ischemic responses, defined as two or more segments of redistribution, were observed in 297. Of these, 70 underwent cardiac catheterization and 25 underwent coronary revascularization procedures. Adverse outcomes affected 46% of the coronary angiography group and 44% of the control group (p = NS). Patients who underwent coronary angiography and were considered for myocardial revascularization had fewer cardiac events with a subsequent vascular operation than did the control subjects. However, any possible benefit from invasive cardiac evaluation was offset by the three deaths and two myocardial infarctions (MIs) that complicated the cardiac evaluation. There was no significant difference between the angiography group and the matched control subjects with respect to perioperative nonfatal MI (13% vs 9%), fatal MI (4% vs 3%), late nonfatal MI (16% vs 19%), or late cardiac death (10% vs 13%). In long-term follow-up, MIs occurred later in patients who underwent coronary angiography than the control subjects (p = 0.049), but this difference was not associated with an improvement in the overall survival rate. CONCLUSIONS: The risks of extended cardiac evaluation and treatment did not produce any improvement in either the perioperative or the long-term survival rate. For most vascular surgery patients who have a positive result of a DT scan, coronary angiography does not provide any additional useful information. 相似文献
26.
27.
28.
29.
30.