全文获取类型
收费全文 | 8502篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 1篇 |
综合类 | 5篇 |
化学工业 | 38篇 |
金属工艺 | 5篇 |
建筑科学 | 3篇 |
能源动力 | 4篇 |
轻工业 | 13篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
武器工业 | 1篇 |
无线电 | 20篇 |
一般工业技术 | 13篇 |
冶金工业 | 8367篇 |
原子能技术 | 1篇 |
自动化技术 | 29篇 |
出版年
2020年 | 3篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2014年 | 4篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 6篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 11篇 |
2004年 | 14篇 |
2003年 | 14篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 279篇 |
1998年 | 2680篇 |
1997年 | 1484篇 |
1996年 | 951篇 |
1995年 | 549篇 |
1994年 | 420篇 |
1993年 | 526篇 |
1992年 | 64篇 |
1991年 | 103篇 |
1990年 | 100篇 |
1989年 | 87篇 |
1988年 | 93篇 |
1987年 | 91篇 |
1986年 | 95篇 |
1985年 | 65篇 |
1984年 | 2篇 |
1983年 | 9篇 |
1982年 | 35篇 |
1981年 | 38篇 |
1980年 | 77篇 |
1979年 | 2篇 |
1978年 | 12篇 |
1977年 | 182篇 |
1976年 | 432篇 |
1975年 | 9篇 |
1963年 | 2篇 |
1955年 | 7篇 |
1954年 | 1篇 |
排序方式: 共有8504条查询结果,搜索用时 0 毫秒
91.
The treatment of alcoholism has changed during the past 2 decades. Notable developments have occurred in pharmacotherapy, psychotherapy, and health-care delivery. A better understanding of the biologic basis for addiction has led to clinical trials of medications that target neuroreceptors. One such medication is the opiate antagonist naltrexone, which decreases the craving for alcohol. Psychosocial interventions continue to be the mainstay of alcohol treatment programs. The efficacy of three different therapies was demonstrated in a study called Project MATCH (Matching Alcoholism Treatments to Client Heterogeneity). This study, however, did not prove the patient-treatment "matching" hypothesis. In addition to therapies provided by addiction specialists, interest is growing in the use of brief motivational techniques in primary-care settings. As the field of addiction responds to an unfolding health-care delivery system, a broader range of treatment options in conjunction with a greater opportunity to individualize patient care is evolving. 相似文献
92.
93.
94.
短消息平台的原理与设计 总被引:15,自引:0,他引:15
结合作者的实际工作经验,介绍了移动短消息的收发原理和短消息平台的体系结构、设计方法,并以本文作者负责组建的青岛短消息平台为例,介绍了其中的系统分析、系统设计、体系结构和功能构成等关键技术问题. 相似文献
95.
Abstract. A new hybrid classifier is proposed which utilizes the advantages of the maximum likelihood classifier and the parallelepiped classifier. The new hybrid classifier reduces the processing time more substantially than the conventional one by introducing a lower boundary for each class. The rate of misclassification is comparable to that of maximum likelihood classifier. Performance of the conventional and the new method are compared by an example. 相似文献
96.
CA Farman K Watkins B van Hoozen JA Last H Witschi KE Pinkerton 《Canadian Metallurgical Quarterly》1999,20(2):303-311
Sprague-Dawley rats were exposed to 0.8 ppm ozone (O3), to 14.4 ppm nitrogen dioxide (NO2), or to both gases simultaneously for 6 h per day for up to 90 d. The extent of histopathologic changes within the central acinus of the lungs was compared after 7 or 78 to 90 d of exposure using morphometric analysis by placement of concentric arcs radiating outward from a single reference point at the level of the bronchiole- alveolar duct junction. Lesions in the lungs of rats exposed to the mixture of gases extended approximately twice as far into the acinus as in those exposed to each individual gas. The extent of tissue involvement was the same at 78 to 90 d as noted at 7 d in all exposure groups. At the end of exposure, in situ hybridization for procollagen types I and III demonstrated high levels of messenger RNA within central acini in the lungs of animals exposed to the combination of O3 and NO2. In contrast, animals exposed to each individual gas had a similar pattern of message expression compared with that seen in control animals, although centriacinar histologic changes were still significantly different from control animals. We conclude that the progressive pulmonary fibrosis that occurs in rats exposed to the combination of O3 and NO2 is due to sustained, elevated expression of the genes for procollagen types I and III. This effect at the gene level is correlated with the more severe histologic lesions seen in animals exposed to both O3 and NO2 compared with those exposed to each individual gas. In contrast, the sustained expression of the procollagen genes is not associated with a shift in the distribution of the lesions because the area of change in each group after 7 d of exposure was the same as after 78 to 90 d of exposure. 相似文献
97.
98.
99.
100.
P Jacquemin D Depetris MG Mattei JA Martial I Davidson 《Canadian Metallurgical Quarterly》1999,55(1):127-129
The tetrapeptide Ala-lle-Gly-Met bound to a Wang resin via the methionine residue was studied by NMR under MAS conditions and compared to the same peptide in solution. The bound peptide exhibits average linewidths superior to those observed for the peptide in solution. The origin of the residual NMR linewidth observed for the bound form was investigated. The dynamics of the peptide is shown to be only marginally responsible for the increased linewidth; the major cause of the line broadening appears to be nonaveraged magnetic susceptibility differences. 相似文献