全文获取类型
收费全文 | 6800篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 25篇 |
金属工艺 | 1篇 |
机械仪表 | 1篇 |
建筑科学 | 2篇 |
能源动力 | 1篇 |
轻工业 | 6篇 |
石油天然气 | 2篇 |
无线电 | 5篇 |
一般工业技术 | 31篇 |
冶金工业 | 6719篇 |
原子能技术 | 1篇 |
自动化技术 | 8篇 |
出版年
2017年 | 1篇 |
2014年 | 1篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 4篇 |
2006年 | 3篇 |
2005年 | 5篇 |
2004年 | 10篇 |
2003年 | 16篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 6篇 |
1999年 | 215篇 |
1998年 | 2307篇 |
1997年 | 1285篇 |
1996年 | 809篇 |
1995年 | 421篇 |
1994年 | 336篇 |
1993年 | 415篇 |
1992年 | 37篇 |
1991年 | 47篇 |
1990年 | 53篇 |
1989年 | 47篇 |
1988年 | 54篇 |
1987年 | 56篇 |
1986年 | 53篇 |
1985年 | 36篇 |
1984年 | 1篇 |
1983年 | 18篇 |
1982年 | 24篇 |
1981年 | 30篇 |
1980年 | 61篇 |
1979年 | 3篇 |
1978年 | 13篇 |
1977年 | 136篇 |
1976年 | 277篇 |
1975年 | 11篇 |
1973年 | 1篇 |
1955年 | 3篇 |
排序方式: 共有6802条查询结果,搜索用时 0 毫秒
71.
MJ Hurley C Brown E Miller DS deJongh MS Litwin 《Canadian Metallurgical Quarterly》1977,112(2):222-225
Stored human blood of varying age was passed through polyurethane foam (Bentley) micropore blood transfusion filters. Passage through these filters resulted in decreased screen filtration pressure (SFP) of the blood and increased filter weights. Numerous microaggregates were removed and SFP returned to normal after filtration. Occlusion of the filter occurred after passage of only 2 units of whole blood. On the basis of this research, we conclude that polyurethane foam (Bentley) micropore blood transfusion filters are effective in removal of microaggregates from stored human blood. Because the filtering capacity is not great, it is recommended that when these filters are used during transfusion a new filter be used for each unit of blood administered. 相似文献
72.
We determined the relationship between mouth occlusion pressure and diaphragmatic electromyography during CO2 rebreathing with and without inspiratory flow resistance. Diaphragmatic electromyography was measured as a moving time average; occlusion pressures were measured 150 msec after onset of an inspiratory effort against a closed airway (P.15). P.15 versus diaphragmatic electromyographic plots during CO2 rebreathing with and without inspiratory flow resistance were linear. In 3 subjects the slope of P.15 versus diaphragmatic electromyography was unchanged with inspiratory flow resistance whereas in 3 others the slope increased, indicating greater inspiratory force for a given degree of diaphragmatic activity. We concluded that under unloaded conditions P.15 is a reliable index of respiratory neural output but may no longer reflect only inspiratory motoneuron drive during mechanical loading. 相似文献
73.
74.
delta9-Tetrahydrocannabinol (THC) was compared with diphenylhydantoin (DPH), phenobarbital (PB) and chlordiazepoxide (CDP) using two electroshock procedures to determine anticonvulsant activity in mice, i.e., electroshock seizure threshold (EST) and the reduced EST caused by hyponatremia (injection of isotonic glucose). Using doses of each drug which were ineffective against MES, only CDP (10.0 mg/kg) was able to raise the EST by 20%. The lowered EST due to hyponatremia was reveresed by al four drugs. In these tests latency to convulsions and lethality associated with electroshock were more sensitive to THC. 相似文献
75.
76.
77.
The adult cuticular wing of Drosophila is covered by an array of distally pointing hairs that reveals the planar polarity of the wing. We report here that mutations in dachsous disrupt this regular pattern, and do so by affecting frizzled signaling. dachsous encodes a large membrane protein that contains many cadherin domains and dachsous mutations cause deformed body parts. We found that mutations in dachsous also result in a tissue polarity phenotype that at the cellular level is similar to frizzled, dishevelled and prickle, as many cells form a single hair of abnormal polarity. Although their cellular phenotype is similar to frizzled, dishevelled and prickle, dachsous mutant wings display a unique and distinctive abnormal hair polarity pattern including regions of reversed polarity. The development of this pattern requires the function of frizzled pathway genes suggesting that in a dachsous mutant the frizzled pathway is functioning - but in an abnormal way. Genetic experiments indicated that dachsous was not required for the intracellular transduction of the frizzled signal. However, we found that dachsous clones disrupted the polarity of neighboring wild-type cells suggesting the possibility that dachsous affected the intercellular signaling function of frizzled. Consistent with this hypothesis we found that frizzled clones in a dachsous mutant background displayed enhanced domineering non-autonomy, and that the anatomical direction of this domineering non-autonomy was altered in regions of dachsous wings that have abnormal hair polarity. The direction of this domineering nonautonomy was coincident with the direction of the abnormal hair polarity. We conclude that dachsous causes a tissue polarity phenotype because it alters the direction of frizzled signaling. 相似文献
78.
R Wikaningrum J Highton A Parker M Coleman PA Hessian PJ Roberts-Thompson MJ Ahern MD Smith 《Canadian Metallurgical Quarterly》1998,41(10):1783-1797
OBJECTIVE: To investigate the production of proinflammatory cytokines and expression of cell adhesion molecules in the rheumatoid nodule. METHODS: Cytokine content (tumor necrosis factor alpha [TNFalpha], interleukin-1beta [IL-1beta], and IL-1 receptor antagonist [IL-1Ra]), at the messenger RNA (mRNA) and protein levels, and cell adhesion molecule expression were studied in 16 rheumatoid nodules and 6 synovial membranes. RESULTS: Macrophages in the rheumatoid nodules contained TNFalpha, IL-1beta, and IL-1Ra mRNA and protein, particularly in perivascular cells of the stroma and in the palisading layer. All cell adhesion molecules studied were expressed in both the rheumatoid nodules and synovial membranes, with increased expression of E-selectin in the rheumatoid nodule compared with the synovial membrane, and with the absence of vascular cell adhesion molecule 1 expression on cells of the palisading layer in the rheumatoid nodule. CONCLUSION: The presence of similar proinflammatory cytokines and cell adhesion molecules in the rheumatoid nodule and synovial membrane suggests that similar pathogenic processes result in the chronic inflammation and tissue destruction in these lesions. 相似文献
79.
80.