全文获取类型
收费全文 | 2309篇 |
免费 | 14篇 |
国内免费 | 3篇 |
学科分类
工业技术 | 2326篇 |
出版年
2022年 | 6篇 |
2021年 | 7篇 |
2020年 | 12篇 |
2019年 | 5篇 |
2018年 | 18篇 |
2017年 | 10篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 14篇 |
2013年 | 27篇 |
2012年 | 9篇 |
2011年 | 14篇 |
2010年 | 18篇 |
2009年 | 16篇 |
2008年 | 15篇 |
2007年 | 32篇 |
2006年 | 13篇 |
2005年 | 29篇 |
2004年 | 21篇 |
2003年 | 33篇 |
2002年 | 24篇 |
2001年 | 19篇 |
2000年 | 15篇 |
1999年 | 68篇 |
1998年 | 552篇 |
1997年 | 304篇 |
1996年 | 249篇 |
1995年 | 124篇 |
1994年 | 109篇 |
1993年 | 117篇 |
1992年 | 17篇 |
1991年 | 41篇 |
1990年 | 41篇 |
1989年 | 36篇 |
1988年 | 43篇 |
1987年 | 26篇 |
1986年 | 28篇 |
1985年 | 13篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 36篇 |
1976年 | 75篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1970年 | 5篇 |
排序方式: 共有2326条查询结果,搜索用时 15 毫秒
991.
992.
993.
Using Raman spectroscopy, we demonstrate that low levels of beta-carotene, lycopene, and xanthophyll give rise to resonance enhanced bands in blood plasma. These results explain the significance of previously unidentified spectral maxima which have been related to the state of health of the blood donor. 相似文献
994.
995.
996.
A 34-month-old girl presented with a clinical picture of Kenny syndrome. The clinical manisfestations included growth retardation, persistent open anterior fontanelle, prominent forehead, mid-facial dysplasia, hypocalcemic tetany and characteristic radiologic skeletal abnormalities. Serum levels of immunoreactive parathyroid hormone (PTH) remained inappropriately low during hypocalcemic episodes in the neonatal period; indicating that hypocalcemia was a consequence of the hypoparathyroid state. This is the first reported case of Kenny syndrome in Taiwan. The literature on the pathogenesis, etiology and genetic basis of this disorder is reviewed in this paper. 相似文献
997.
Q Shi JD Gaylor R Cousins J Plevris PC Hayes MH Grant 《Canadian Metallurgical Quarterly》1998,22(12):1023-1030
In many bioartificial liver systems currently being designed and evaluated for use in fulminant hepatic failure, direct contact is required between the patient's blood and the liver cells in the device. The efficacy of such devices will be influenced by the interaction of fulminant hepatic failure (FHF) patient serum with the cells. We have found that FHF serum inhibits the growth rate and the synthesis of DNA, RNA, and protein; disturbs glutathione homeostasis; and induces morphological changes in cultured human Hep G2 cells. These interactions should influence the design of bioartificial liver devices based on proliferating cell lines and indicate the requirement to pretreat FHF patient plasma to reduce the toxin load. 相似文献
998.
JE Ahlskog SC Waring RC Petersen C Esteban-Santillan UK Craig PC O'Brien MF Plevak LT Kurland 《Canadian Metallurgical Quarterly》1998,51(6):1672-1677
OBJECTIVES: To assess whether olfactory deficits are present in the general Guamanian Chamorro population and to evaluate olfaction in each of the four neurodegenerative disease syndromes of Guam: ALS, pure parkinsonism, pure dementia, and the combined parkinsonism-dementia complex (PDC). BACKGROUND: Olfactory dysfunction was previously reported in patients with PDC of Guam. METHODS: We developed a culturally adjusted olfactory test battery, derived from the original University of Pennsylvania Smell Identification Test (UPSIT), and administered this to Chamorro residents with ALS (n=9), pure parkinsonism (n=9), pure dementia (n=11), PDC (n=31), and 53 neurologically normal Chamorro and 25 North American control subjects. RESULTS: Similar, marked olfactory dysfunction was found in all four syndromes of Guamanian neurodegenerative disease. This correlated poorly with measures of parkinsonism and cognition. In the neurologically normal Chamorro control group, six subjects (11%) had very low olfactory scores; these were less than the lowest North American score, raising a question of subclinical neurodegenerative disease. CONCLUSIONS: Marked olfactory deficits are common to all four Guamanian neurodegenerative syndromes, and suggest the possibility of similar central neuropathologic substrates. The deficit in the Guamanian ALS group contrasts with idiopathic ALS, in which olfactory function has been reported to be only slightly compromised. 相似文献
999.
1000.
Previous studies have shown that mouse adenovirus type-1 (MAV-1) caused a fatal hemorrhagic encephalitis in certain strains of mice. C57BI/6 mice exhibited 100% mortality when given as little 10(3) plaque-forming units (PFU) of MAV, in contrast to BALB/c mice which were resistant to as many as 10(6) PFU. Susceptible animals died with a flaccid paralysis on the 3rd or 4th day after inoculation. The brains and spinal cords of these animals displayed numerous petechial hemorrhages that were found in virtually all areas of the brain, but were more numerous in white matter. In this paper, immunohistochemistry and electron microscopy were used to identify the viral target of replication within the CNS of susceptible mice. These studies showed that the CNS vascular endothelial cell was the primary site of viral replication within the CNS of mice infected with MAV-1. Characterization of cytokine mRNA levels and disease course in immunodeficient mice revealed that the host immune response played little, if any, role in the pathogenesis of MAV-1 disease in susceptible mice and was not responsible for the resistance of BALB/c mice. These results support the conclusion that disease course and outcome in susceptible and resistant strains of mice were determined primarily by the ability of the virus to replicate within the CNS vascular endothelium. 相似文献