全文获取类型
收费全文 | 479篇 |
免费 | 5篇 |
专业分类
电工技术 | 2篇 |
综合类 | 2篇 |
化学工业 | 41篇 |
机械仪表 | 1篇 |
能源动力 | 4篇 |
轻工业 | 6篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 6篇 |
一般工业技术 | 7篇 |
冶金工业 | 412篇 |
出版年
2023年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2013年 | 2篇 |
2012年 | 7篇 |
2011年 | 3篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2007年 | 2篇 |
2006年 | 6篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 126篇 |
1997年 | 66篇 |
1996年 | 51篇 |
1995年 | 32篇 |
1994年 | 24篇 |
1993年 | 28篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 20篇 |
1976年 | 32篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有484条查询结果,搜索用时 15 毫秒
471.
472.
Immune and inflammatory responses occurring during dermal infestation by larvae of Lucilia cuprina can retard larval growth and development. This study examined the effect of 4 classes of humoral inflammatory mediators on larval growth in an in vitro assay. Mediators of plasma leakage (histamine, bradykinin, platelet-activating factor and serotonin), leucocyte chemotactic agonists (activated complement, leukotriene B4 and interleukin-8), effector molecules of immune responses (interleukin-1 beta, tumour necrosis factor-alpha and interferon-gamma) and endotoxin all failed to inhibit larval growth. In contrast, immunoglobulins isolated from immune serum caused marked retardation of larval growth. The results suggest that humoral mediators of inflammatory and immune responses do not play a role in immune defence against Lucilia cuprina. 相似文献
473.
J Hoyle IG Yulug K Johnstone PJ Scambler EM Fisher 《Canadian Metallurgical Quarterly》1996,97(1):117-120
A 25-year-old man with hemophilia A who had received concentrated plasma and plasma factor VIII products since childhood presented with a productive cough and a fever. The CD4/CD8 ratio of peripheral lymphocyte subsets was very low and the serum was positive for anti-HIV antibodies. The chest roentgenogram showed bilateral multiple nodules with cavity formation. The patient underwent transbronchial lung biopsy, and the specimen obtained had Pneumocystic carinii organisms. The patient was treated with sulfamethoxazole and trimethoprim compounds, and with inhaled pentamizine. His condition improved. Patients with pulmonary pneumocystosis usually present with interstitial infiltrates spreading from the hilium to the periphery of the lungs, and nodular and cavitary lesions are unusual pulmonary radiographic findings in this condition. 相似文献
474.
We studied major malformations in 5,581 infants with Down syndrome (DS) from three registers of congenital malformations. THe prevalence at birth of 23 different malformations was compared with the program-specific rates for each malformation in non-DS infants. An about 300 times risk increase was seen for annular pancreas, cataracts and duodenal atresia and an about 100 times risk increase for megacolon and small choanal atresia. Esophageal, anal and small bowel atresia, preaxial polydactyly, and omphalocele all showed risk increases between 10 and 30 times. Statistically significantly elevated risk ratios around 3-5 were seen for cleft palate, cleft lip/palate, and limb deficiencies. No increased risk was seen for neural tube defects, hydrocephaly, microtia, renal agenesis or severe dysgenesis, hypospadias or polydactyly other than preaxial. Oral clefts were more often present in DS in the Swedish material than in the other two materials. Cardiac defects were registered in 26% of all cases (varying between programs) but 28% of the cardiac defects were unspecified. DS infants born to women younger than 25 years had a significantly increased risk for megacolon and there was a trend increasing risk for esophageal or anal atresia with maternal age. A decreased risk for cardiac defect in DS infants born to teenage mothers was found, quite pronounced for endocardial cushion defects and ventricular septum defects. There were no statistically significant differences in the sex distribution of specific malformations in infants with DS and in non-DS infants. 相似文献
475.
The effects of intracellular levels of polyamines on both the in vivo inhibition of protein synthesis and the decrease of translation accuracy induced by streptomycin have been studied in polyamine-auxotrophic strains of Escherichia coli infected with the MS2 bacteriophage. The amount of viral coat protein formed was strongly reduced upon addition of increasing concentrations of streptomycin to polyamine-supplemented bacteria. In contrast, the antibiotic almost did not inhibit coat protein synthesis in polyamine-starved cells. The increase of mistranslation frequency elicited by streptomycin was only observed in bacteria grown with putrescine. In these cells several coat protein-satellites were detected after two-dimensional gel electrophoresis. These proteins, more basic than the normal MS2 coat protein, contain multiple substitutions of lysine for asparagine. 相似文献
476.
477.
To elucidate the effect of antioxidants aevit and glutaminic acid on the course of bronchial asthma (BA) and free radical processes in this disease, 54 BA patients were divided into 2 groups: glucocorticoid-untreated and glucocorticoid-treated. Each of two subgroups made of these groups either received antioxidants (AO) or not. The response was assessed by clinical BA symptoms and free radical processes reflecting production of active oxygen forms by leukocytes (PAOFL) and free radical peroxidation (FRPO). PAOFL was studied using luminol-dependent chemiluminescence (CL). CL basal and stimulated values were calculated. FRPO was measured by plasma levels of malonic dialdehyde. Aevit and glutaminic acid treated BA patients improved clinically and exhibited reduced CL of PAOFL and malonic dialdehyde in plasma compared to BA patients on conventional therapy or conventional therapy plus glucocorticoids. Aevit and glutaminic acid are recommended for BA patients. 相似文献
478.
A study was made of the dynamics of the colony-forming and migration capacity of the polypotent stem hemopoietic cells of the bone marrow of the F1 (CBA X C57BL) mice after the hydrocortisone administration. The relative count of the stem hemopoietic cells in the bone marrow increased on the 3rd day after the hydrocortisone administration. This elevation was maximal on the 5th day after the hydrocortisone administration. On the 8th day the stem hemopoietic cell count decreased to the normal level. 相似文献
479.
Accurate electrocardiographic diagnosis of myocardial ischemia or infarction is difficult in patients with the Wolff-Parkinson-White syndrome; however, myocardial ischemia may also have profound effects on the electrophysiologic characteristics of the bypass tract in these patients. Comparison of studies performed during and two months following an episode of significant myocardial ischemia demonstrated substantial prolongation of the refractoriness of the bypass tract during the period of ischemia. Bypass refractoriness was prolonged by 196 msec, yet atrioventricular nodal refractoriness was not significantly different from normal. These studies, therefore, suggest that, on occasion, the presence of acute myocardial ischemia may, in fact, obscure the electrocardiographic diagnosis of the Wolff-Parkinson-White syndrome. 相似文献
480.