全文获取类型
收费全文 | 2000篇 |
免费 | 13篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 6篇 |
综合类 | 2篇 |
化学工业 | 70篇 |
金属工艺 | 36篇 |
机械仪表 | 11篇 |
建筑科学 | 20篇 |
矿业工程 | 5篇 |
能源动力 | 6篇 |
轻工业 | 89篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
武器工业 | 1篇 |
无线电 | 47篇 |
一般工业技术 | 118篇 |
冶金工业 | 1513篇 |
原子能技术 | 15篇 |
自动化技术 | 71篇 |
出版年
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 11篇 |
2015年 | 4篇 |
2014年 | 14篇 |
2013年 | 38篇 |
2012年 | 24篇 |
2011年 | 23篇 |
2010年 | 12篇 |
2009年 | 14篇 |
2008年 | 13篇 |
2007年 | 23篇 |
2006年 | 22篇 |
2005年 | 19篇 |
2004年 | 13篇 |
2003年 | 11篇 |
2002年 | 17篇 |
2001年 | 12篇 |
2000年 | 6篇 |
1999年 | 53篇 |
1998年 | 456篇 |
1997年 | 281篇 |
1996年 | 182篇 |
1995年 | 111篇 |
1994年 | 79篇 |
1993年 | 118篇 |
1992年 | 26篇 |
1991年 | 24篇 |
1990年 | 28篇 |
1989年 | 19篇 |
1988年 | 16篇 |
1987年 | 16篇 |
1986年 | 21篇 |
1985年 | 26篇 |
1984年 | 14篇 |
1983年 | 13篇 |
1982年 | 14篇 |
1981年 | 15篇 |
1980年 | 20篇 |
1979年 | 10篇 |
1978年 | 15篇 |
1977年 | 29篇 |
1976年 | 72篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1973年 | 10篇 |
1971年 | 4篇 |
1970年 | 5篇 |
1969年 | 4篇 |
1967年 | 5篇 |
排序方式: 共有2014条查询结果,搜索用时 15 毫秒
91.
XF Zhao T Colaizzo-Anas NJ Nowak TB Shows RW Elliott PD Aplan 《Canadian Metallurgical Quarterly》1998,47(2):319-322
OBJECTIVE: We prospectively compared the ability of two techniques--bone scintigraphy with single-photon emission computed tomography (SPECT) of the chest and CT of the chest--to reveal potential osteosarcoma metastases of the lung. SUBJECTS AND METHODS: Our study included 27 patients with osteosarcoma who prospectively underwent both bone scintigraphy with SPECT of the chest and CT of the chest. The imaging results were compared with outcome or pathologic analysis of any lung lesions found. RESULTS: Eight (30%) of the 27 patients had pulmonary metastases. Four of these eight patients had positive results on both CT studies and bone SPECT studies, with additional lesions detected with bone SPECT in two of these four patients. The other four patients with pulmonary metastases had positive results on CT studies, whereas the results of bone SPECT studies remained negative. The results of bone SPECT studies were negative in the 19 patients without pulmonary metastases. CT, however, showed abnormalities in seven (37%) of the 19 patients, which were eventually attributed to benign conditions. CONCLUSION: Negative results on a bone SPECT study of the chest should not be used to exclude the possibility of lung metastases. However, if the results are positive, a bone SPECT study can be used to confirm abnormalities seen on CT scans and may also reveal subtle lesions missed on CT scans. 相似文献
92.
In a prospective study at a single centre between August 1995 and March 1996, 193 patients with elbow injuries were studied. Standard radiographs of the elbows were taken. A total of 181 X-rays were reported by one person concerning the presence or absence of fractures and fat-pad signs. The radiographs were analysed and positive predictive values were calculated for the presence of the fat-pad sign with radial head/neck fractures. The sensitivity for radial head/neck fracture is 85.4 per cent, while the specificity is only 50 per cent. The fat-pad sign must be used cautiously as an indicator of radial head/neck fractures; its absence is a more reliable indicator of the absence of a radial head/ neck fracture. 相似文献
93.
94.
In studies of T cell responses to synthetic peptides we have observed agonist and antagonist activities associated with contaminants identified within the parent synthesis. The synthesis of two candidate analogues implied by a peptide contaminant formed during the synthesis of La 51-58 (IMIKFNRL) has been carried out. The peptide contaminant was 17-18 Da smaller than the parent peptide consistent with a modified asparagine residue at position 6 and so we synthesised both an aspartimide and a nitrile analogue, representing cyclisation or dehydration of the asparagine residue. The candidate aspartimide and nitrile analogues both bound empty MHC class I molecules to form allo determinants recognised by monoclonal antibodies. These results demonstrate that altered synthetic peptides can bind class I MHC molecules and prompt caution in the use of synthetic peptides as a source of immunising antigen. 相似文献
95.
The long cane can be used as a mobility aid for visually handicapped people. According to a questionnaire completed by Japanese cane users, it seems they are not always satisfied with using long canes for a variety of reasons. In this study, hand-transmitted vibration from the long cane due to tapping the ground was measured because an exposure to repeated shock-type tapping vibration may affect the hand-arm system. A sighted female wearing a blindfold participated. The measurement was carried out in different conditions with three different ground materials both indoor and outdoors. The vibration at three axes of the cane grip and one axis at the wrist were measured. The pinch forces between an index finger and the grip were also measured using a strain gauge in order to observe how the vibration characteristics depend on the changing forces. Measurement, evaluation and assessment were based on the International Standard (ISO 5349). The estimated daily exposure time and the transmissibility were obtained in order to investigate the severity of the hand-transmitted vibration caused by the long cane. It was found that the characteristics of tapping vibration depend on different measurement conditions and the vibration might be associated with a health risk over a long life span. 相似文献
96.
97.
98.
99.
100.
Electron irradiation damage at 1 MeV has been studied in zircomium and Zircaloy-2, in the temperature range 315 to 725 K, using a high voltage microscope. At low doses, the damage takes the form of perfect prismatic dislocation loops of interstitial character, with Burgers vectors of the type . The loops form in bands parallel to the trace of the basal plane, by a process of preferred nucleation. A significant proportion of the loops appear to nucleate on {112?0} planes in a pure edge configuration and reorient during growth to reduce their energy. Continued irradiation causes loop growth and interactions, resulting in the formation of a dislocation network. The results are compared with data from neutron- and ion-irradiation studies. 相似文献