全文获取类型
收费全文 | 645篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 5篇 |
金属工艺 | 1篇 |
矿业工程 | 1篇 |
轻工业 | 2篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
一般工业技术 | 1篇 |
冶金工业 | 631篇 |
自动化技术 | 3篇 |
出版年
2020年 | 1篇 |
2016年 | 1篇 |
2013年 | 1篇 |
2011年 | 1篇 |
2003年 | 4篇 |
2000年 | 2篇 |
1999年 | 18篇 |
1998年 | 195篇 |
1997年 | 120篇 |
1996年 | 80篇 |
1995年 | 44篇 |
1994年 | 30篇 |
1993年 | 31篇 |
1992年 | 11篇 |
1991年 | 21篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 3篇 |
1976年 | 14篇 |
排序方式: 共有648条查询结果,搜索用时 500 毫秒
61.
62.
JM Benson IY Chang YS Cheng FF Hahn CH Kennedy EB Barr KR Maples MB Snipes 《Canadian Metallurgical Quarterly》1995,28(2):232-244
The goals of this study were to (1) determine the effects of repeated inhalation of relatively insoluble nickel oxide (NiO) and highly soluble nickel sulfate hexahydrate (NiSO4.6H2O) on lung particle clearance, (2) investigate the effects of repeated inhalation of NiO or NiSO4 on the pulmonary clearance of subsequently inhaled 85Sr-labeled microspheres, (3) correlate the observed effects on clearance with accumulated Ni lung burden and associated pathological changes in the lung, and (4) compare responses in F344 rats and B6C3F1 mice. Male F344/N rats and B6C3F1 mice were exposed whole-body to either NiO or NiSO4.6H2O 6 hr/day, 5 days/week for up to 6 months. NiO exposure concentrations were 0, 0.62, and 2.5 mg NiO/m3 for rats and 0, 1.25, and 5.0 mg NiO/m3 for mice. NiSO4.6H2O exposure concentrations were 0, 0.12, and 0.5 mg NiSO4.6H2O/m3 for rats and 0, 0.25, and 1.0 mg NiSO4.6H2O/m3 for mice. After 2 and 6 months of whole-body exposure, groups of rats and mice were acutely exposed nose-only to 63NiO (NiO-exposed animals only), 63NiSO4.6H2O (NiSO4.6H2O-exposed animals only), or to 85Sr-labeled polystyrene latex (PSL) microspheres (both NiO- and NiSO4.6H2O-exposed animals) to evaluate lung clearance. In addition, groups of rats and mice were euthanized after 2 and 6 months of exposure and at 2 and 4 months after the whole-body exposures were completed to evaluate histopathological changes in the left lung and to quantitate Ni in the right lung. Repeated inhalation of NiO results in accumulation of Ni in lungs of both rats and mice, but to a greater extent in lungs of rats. During the 4 months after the end of the whole-body exposures, some clearance of the accumulated Ni burden occurred from the lungs of rats and mice exposed to the lower, but not the higher NiO exposure concentrations. Clearance of acutely inhaled 63NiO was also impaired in both rats and mice, with the extent of impairment related to both exposure concentration and duration. However, the clearance of acutely inhaled 85Sr PSL microspheres was not impaired. The repeated inhalation of NiO resulted in alveolar macrophage (AM) hyperplasia with accumulation of NiO particles in both rats and mice, chronic alveolitis in rats, and interstitial pneumonia in mice. These lesions persisted throughout the 4-month recovery period after the NiO whole-body exposures were terminated. In contrast, repeated inhalation of NiSO4.6H2O did not result in accumulation of Ni in lungs of either rats or mice and did not affect the clearance of 63NiSO4.6H2O inhaled after either 2 or 6 months of NiSO4.6H2O exposure. Clearance of the 85Sr-labeled microspheres was significantly impaired only in rats exposed to the microspheres after 2 months of exposure to NiSO4.6H2O. Histopathological changes in rats were qualitatively similar to those seen in NiO-exposed rats. Only minimal histopathological changes were observed in NiSO4.6H2O-exposed mice. These results suggest that repeated inhalation of NiO at levels resulting in AM hyperplasia and alveolitis may impair clearance of subsequently inhaled NiO. The potential effects of repeated inhalation of soluble NiSO4.6H2O on the clearance of subsequently inhaled poorly soluble particles are less clear. 相似文献
63.
KH Yeh MT Lin DT Lin JL Tang LT Lui JF Lin YS Chang AL Cheng SC Yu KJ Chang YC Chen 《Canadian Metallurgical Quarterly》1998,49(3):237-244
BACKGROUND: Epidemiologic studies are necessary to determine the prevalence of allergic diseases. This varies widely depending on allergen preparations and patients studied. OBJECTIVE: To investigate the prevalence of atopic disease, skin test reactivity, total and specific IgE to common allergens, and other variables in a sample of students from Málaga, southern Spain. METHODS: Three hundred sixty-five students (age 17.9 +/- 1.18) were interviewed by an allergist. Skin prick tests were performed with Dermatophagoides pteronyssinus, Artemisia vulgaris, Plantago lanceolata, Chenopodium album, Olea europaea, Phleum pratense, Parietaria judaica, Cynodon dactylon, Alternaria tenuis, and cat dander. Total and specific IgE to D. pteronyssinus, Olea, and Parietaria were determined. RESULTS: Of all subjects studied, 19.9% suffered from rhinoconjunctivitis, 4.1% rhinoconjunctivitis plus asthma, 3.1% asthma alone, and 0.8% atopic dermatitis; 46.4% had a positive skin test to at least one allergen (28.2% to D. pteronyssinus, 20.4% to Olea, 13.8% to Phleum); and 43% had total IgE > 100 kU/L and 44.7% a family history of atopy. Allergic symptoms were strongly associated with skin test positivities and family allergic history. Patients with asthma or skin prick test positive had higher total IgE values than others (P < .01). There was a significant correlation between specific IgE values and wheal size in skin test. CONCLUSIONS: Our findings confirm the high prevalence of atopic diseases, and the close relationship of skin tests reactivity (or presence of specific IgE) to allergens with symptoms of asthma and rhinitis. The presence of a family history of allergic diseases influences the development of positive skin tests and atopic illness. Dermatophagoides pteronyssinus and pollen of Olea europaea were found to be the most common allergens. 相似文献
64.
65.
66.
67.
Antagonism of l-stepholidine against bromocriptine-inhibition on prolactin level in lactational rats
AIM: To study the antagonism of l-stepholidine (SPD) against bromocriptine (Bro)-inhibition on prolactin (PRL) level. METHODS: Bro (0.5 mg.kg-1.d-1, s.c.) reduced the PRL and caused a dysplasia of mammary gland in lactational rats. The weight growing of newborn rats was retarded. The PRL of the lactational rats was assessed by immunoradiometric assay (IRMA); the weight of newborn rats and development of mammary glands in lactational rats were also examined. Antagonism of SPD was evaluated. RESULTS: SPD (30 & 100 mg.kg-1.d-1, i.p.) obviously antagonized the Bro that induced lowering the PRL level in lactational rats, the PRL was 11 +/- 4 & 23 +/- 6 micrograms.L-1 (NS 7 +/- 2) respectively on d 15 of postpartum and the development of mammary gland in lactational rats was normal. The newborn rats grew rapidly in 11-15 d. CONCLUSION: SPD possessed an antagonism with Bro inhibition on D2 receptors located in the pituitary gland, and was an antagonist of dopamine D2 receptors. 相似文献
68.
A specific regulatory effect of ferrous ion on a biosynthesis of mildiomycin by Streptoverticillium rimofaciens was investigated. The minimal concentration of ferrous ion necessary for the maximal production of mildiomycin was about 8 micrograms/ml. The physiological effects of ferrous ion on the mildiomycin production were examined in the media with and without the ferrous ion. Addition of ferrous ion to the culture medium increased both the mildiomycin production (10 times) and an assimilation of ammonium-nitrogen, activities of peptidase and protease. 相似文献
69.
Bicomponent (fractions S and F) staphylococcal leukocidal toxins (Panton-Valentine leukocidin-Luk and haemolysin gamma-Hlg) were tested for in vitro activity against isolated polymorphonuclear leukocytes (PMNL) and peritoneal macrophages (PMF). For assessment of membrane permeability at subcytolytic concentrations of leukocidin (Luk-S + Luk-F) and haemolysin gamma (HlgA + HlgB) (8-1000 ng/ml), PMNL and PMF were radiolabelled (86Rb, 14C-amino-isobutyric acid (AIB) or 51Cr). All toxins tested caused lysis of human PMNL, although considerable differences were noted in the sensitivity of these cells to Luk and Hlg. Release of 51Cr (at 1000-5000 ng/ml), being a sign of irreversible cell damage and lysis, was preceded, at lower concentrations of the toxins (40 and 200 ng/ml), by the release of large amounts of low-molecular labels--86Rb and 14C-AIB. In another experiment, it was found that release of 86Rb from PMNL incubated with low concentrations of Luk (50 ng/ml) took place after 15-30 minutes of incubation, when no significant amounts of 14C-AIB or 51Cr were released. These findings support the concept of pore formation by staphylococcal leukocidal toxins in membranes of sensitive cells and indicate that a relatively short time is needed for the formation of these pores after binding of the Luk-S and Luk-F components to the membrane. 相似文献
70.