全文获取类型
收费全文 | 1978篇 |
免费 | 4篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 29篇 |
金属工艺 | 2篇 |
机械仪表 | 5篇 |
建筑科学 | 6篇 |
矿业工程 | 1篇 |
能源动力 | 4篇 |
轻工业 | 28篇 |
石油天然气 | 2篇 |
无线电 | 26篇 |
一般工业技术 | 33篇 |
冶金工业 | 1806篇 |
原子能技术 | 4篇 |
自动化技术 | 34篇 |
出版年
2023年 | 3篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 5篇 |
2012年 | 9篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 6篇 |
2008年 | 10篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 10篇 |
1999年 | 56篇 |
1998年 | 516篇 |
1997年 | 301篇 |
1996年 | 203篇 |
1995年 | 101篇 |
1994年 | 96篇 |
1993年 | 124篇 |
1992年 | 21篇 |
1991年 | 32篇 |
1990年 | 32篇 |
1989年 | 32篇 |
1988年 | 44篇 |
1987年 | 35篇 |
1986年 | 29篇 |
1985年 | 23篇 |
1984年 | 2篇 |
1983年 | 12篇 |
1982年 | 14篇 |
1981年 | 21篇 |
1980年 | 12篇 |
1978年 | 2篇 |
1977年 | 52篇 |
1976年 | 108篇 |
1975年 | 3篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1963年 | 1篇 |
1955年 | 1篇 |
1927年 | 2篇 |
排序方式: 共有1982条查询结果,搜索用时 140 毫秒
31.
KE McLaughlin IN Jacobs NW Todd GS Gussack G Carlson 《Canadian Metallurgical Quarterly》1997,107(10):1322-1331
Nasopharyngeal stenosis and oropharyngeal stenosis are rare and challenging problems in the pediatric population. The most common etiology is currently the surgical trauma associated with adenotonsillectomy. Stenosis can vary from a thin band to a complete obstructing cicatrix. Presenting symptoms range from mild hyponasal speech to severe airway obstruction. We present a series of eight children with varying degrees of stenosis and associated symptoms. Choice of treatment varied with the severity of disease. In our series, successful interventions included triamcinolone acetonide injection, lysis of adhesions, rotational and advancement mucosal flaps, and jejunal free flap. Preoperative evaluation and individualized surgical repair are essential for successful treatment. 相似文献
32.
33.
34.
GS Brody 《Canadian Metallurgical Quarterly》1997,100(4):1054-1057
35.
36.
37.
38.
39.
GS Wengler A Lanfranchi T Frusca R Verardi A Neva D Brugnoni S Giliani M Fiorini P Mella F Guandalini E Mazzolari S Pecorelli LD Notarangelo F Porta AG Ugazio 《Canadian Metallurgical Quarterly》1996,348(9040):1484-1487
BACKGROUND: X-linked severe combined immunodeficiency (SCIDXI) is an inherited immune defect which leads to death in infancy from severe infections. The defect is caused by mutations of the IL-2RG gene that encodes for the common gamma chain shared by several cytokine receptors. The disease is characterised by lack of T and NK cells with normal numbers of B cells. SCIDXI can be cured by bone marrow transplantation (BMT) or prevented by abortion after prenatal diagnosis. METHODS: A male fetus was diagnosed as having SCIDXI by molecular, immunophenotypic, and functional analyses. The fetus was injected intraperitoneally under ultrasound guidance with CD34 haematopoietic progenitor cells purified from paternal bone marrow and T-cell depleted by E rosetting. Chimerism analysis was by HLA-DQ alpha typing and gamma-chain staining on cord blood. FINDINGS: A healthy 3.6 kg boy was delivered by caesarean section at 38 weeks of gestation with no clinical or laboratory signs of graft-versus-host disease. Engraftment of donor-derived CD2 cells was found at birth. At 3.5 months of age the infant is well and his T-cell counts and function are normal. INTERPRETATION: In-utero transplantation of haematopoietic progenitor cells allowed immune reconstitution of a fetus with SCIDXI and may be an alternative to elective abortion. Our report should encourage applications of this method to other inherited disorders curable by BMT. 相似文献
40.
The objective of this study was to examine the immunotoxicological effects of the methyl-carbamate pesticide carbaryl via the oral, dermal, or inhalation routes. Male CD rats were exposed to carbaryl 5 d/wk for a 2-wk period. During nose-only inhalation exposures, rats received either 36, 137, or 335 mg/m3 carbaryl in acetone for 6 h. Air only and acetone/air controls were run concurrently. Orally exposed animals received either 1 ml corn oil or 10, 25, or 50 mg/kg carbaryl, while dermally exposed animals received either 2 ml acetone or 100, 500, or 1000 mg/kg carbaryl on their dorsal flank for 6 h. Four days prior to sacrifice, animals from all exposure groups were injected iv with 2 x 10(8) sheep red blood cells (SRBC). The primary immunoglobulin M (IgM) humoral immune response to SRBC was then assessed by measuring SRBC-specific antibody-forming cells (AFC) and levels of serum anti-SRBC IgM antibody, respectively, using the hemolytic plaque assay and an enzyme-linked immunosorbent assay. Individual body weights, spleen, thymus, and liver weights, spleen cell number, and red and white blood cell (RBC, WBC) counts were obtained for each animal. Following nose-only inhalation exposures, dose-dependent decreases in thymus weights, spleen cell number, AFC/spleen, AFC/10(6) splenocytes, and serum levels of SRBC-specific IgM antibody were observed. Significant decreases of 33, 57, and 22% in spleen cell number, AFC/spleen, and thymus weight, respectively, were found at the 335 mg/m3 exposure level. Animals exposed orally to 25 mg/kg carbaryl had a 34% decrease in WBC counts. A 34% decrease in WBC and a 13% increase in RBC counts were observed at the 50 mg/kg oral dose. Significant decreases in liver weights ranging from 11 to 13% were found at all oral exposure levels. Dermal exposure to carbaryl revealed no significant toxicological effects. Results indicate that humoral immune suppression was observed following inhalation, but not following oral or dermal exposures to carbaryl. Immunotoxicological studies evaluating pesticides need to consider relevant exposure routes and dosages for appropriate risk assessment procedures and exposure limits to be established. 相似文献