全文获取类型
收费全文 | 1353篇 |
免费 | 7篇 |
专业分类
电工技术 | 11篇 |
综合类 | 1篇 |
化学工业 | 168篇 |
金属工艺 | 124篇 |
机械仪表 | 58篇 |
建筑科学 | 12篇 |
矿业工程 | 16篇 |
能源动力 | 3篇 |
水利工程 | 22篇 |
石油天然气 | 63篇 |
无线电 | 114篇 |
一般工业技术 | 176篇 |
冶金工业 | 475篇 |
原子能技术 | 85篇 |
自动化技术 | 32篇 |
出版年
2021年 | 17篇 |
2019年 | 14篇 |
2018年 | 29篇 |
2017年 | 29篇 |
2016年 | 25篇 |
2015年 | 13篇 |
2014年 | 28篇 |
2013年 | 39篇 |
2012年 | 39篇 |
2011年 | 37篇 |
2010年 | 31篇 |
2009年 | 36篇 |
2008年 | 33篇 |
2007年 | 26篇 |
2006年 | 28篇 |
2005年 | 22篇 |
2004年 | 21篇 |
2003年 | 13篇 |
2002年 | 17篇 |
2001年 | 27篇 |
2000年 | 15篇 |
1999年 | 20篇 |
1998年 | 131篇 |
1997年 | 78篇 |
1996年 | 62篇 |
1995年 | 39篇 |
1994年 | 25篇 |
1993年 | 36篇 |
1991年 | 16篇 |
1990年 | 19篇 |
1989年 | 16篇 |
1988年 | 19篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 16篇 |
1983年 | 18篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 22篇 |
1979年 | 12篇 |
1978年 | 18篇 |
1977年 | 25篇 |
1976年 | 33篇 |
1975年 | 16篇 |
1974年 | 14篇 |
1973年 | 11篇 |
1972年 | 12篇 |
1971年 | 14篇 |
1970年 | 16篇 |
1969年 | 11篇 |
排序方式: 共有1360条查询结果,搜索用时 15 毫秒
1.
Zakharov A. V. Rozenko S. A. 《Journal of Communications Technology and Electronics》2019,64(4):430-438
Journal of Communications Technology and Electronics - Microstrip band-pass filters (BPFs) containing quarter-wavelength resonators and a Π-shaped half-wavelength resonator placed next to each... 相似文献
2.
3.
这幢位于瑞士比尔郊区的公寓高三层,由8套大小不同的住宅单元所构成,所处位置能够俯瞰整个小镇,具有极佳的视野。下面的部分是跃层式的二层公寓,上面一层则是普通公寓。楼顶为公共活动区域,设有孩子们的游戏室,其屋顶形式与相邻的建筑风格颇为近似。基地东南向的陡坡非常理想地 相似文献
4.
SF Zakharov SH Kwok H Sokoloff HT Chang SP Radko A Chrambach 《Canadian Metallurgical Quarterly》1998,19(10):1625-1630
An automated gel electrophoresis apparatus, recently available commercially, allows one to follow the band during electrophoresis in real time, and lends itself therefore to an evaluation of bandwidth as a function of migration time (the dispersion coefficient), resolution and band shape. These determinations assume the constancy of band area with migration time and at various gel concentrations. The purpose of the present study was to verify these assumptions. Representative proteins and sodium dodecyl sulfate (SDS)-proteins, either natively fluorescent or fluorescein carboxylate labeled, were found to exhibit band areas which approach constancy as a function of migration time in both agarose and polyacrylamide gel electrophoresis, provided that (i) the protein concentration under the band was low enough to obviate self-quenching of fluorescence; (ii) the separation of the protein of interest from contaminants had progressed sufficiently during the time at which band areas were measured; (iii) the baseline under the peak was sufficiently well defined. However, band areas decrease with increasing gel concentration. Protein peaks exhibited leading and trailing tails. The ratio of the combined tail area to total area appeared to be near-constant at varying migration times. However, that ratio increases with increasing gel concentration. The tail area does not appear to be an artifact of fluorometric detection since it is reproduced upon fluorimetric analysis of the protein eluted from gel slices after electrophoresis. However, it may be due to photochemical destruction under the conditions of repetitive fluorometric peak detection. 相似文献
5.
Several studies have reported that the bulk aluminum (Al) concentration is increased in the brain in Alzheimer disease (AD), while other studies have failed to demonstrate an increase. Most of these investigations have had one or more methodological deficiencies, including lack of adequate neuropathological assessment; failure to age-match the control samples; small sample sizes, lacking statistical power; and geographical heterogeneity in the AD and control populations. The present population-based study of 92 clinically and histopathologically diagnosed AD patients and normal elderly nursing home residents was designed to avoid these potential biases. When a subsample of AD cases with the most severe brain pathology was compared with controls having no or minimal pathology, no statistically significant differences were found in the bulk aluminum concentration measured by graphite furnace atomic absorption spectrometry in frontal cortex (1.8 +/- 0.7 vs. 1.7 +/- 0.7 micrograms/g dry wt), temporal cortex (1.4 +/- 0.3 vs. 1.5 +/- 0.5 micrograms/g dry wt), liver (2.0 +/- 1.3 vs. 2.0 +/- 1.2 micrograms/g dry wt), or head of femur (2.4 +/- 1.6 vs. 2.2 +/- 1.0 micrograms/g ash wt). Within the whole series of 92 cases, there was no difference in the bulk aluminum concentration of the frontal cortex between individuals diagnosed as definite, probable, and possible cases of AD using the CERAD (Consortium to Establish a Registry for Alzheimer's Disease) criteria. The density of senile plaques and neurofibrillary tangles in frontal and temporal cortex showed no correlation with the bulk aluminum concentration. Logistic regression analyses, which controlled for age and sex, did not influence outcome for any of the comparisons. The data show conclusively that in AD, bulk aluminum concentration is not increased in two cortical brain regions that are selectively vulnerable to the neuropathological changes associated with this disorder. 相似文献
6.
Forty-seven children afflicted with acute leukemia were studied at the Tata Memorial Hospital Bombay to record the occurrence of oral manifestations prior to and during chemotherapy. Lymphadenopathy was the most frequent single finding suggestive of leukemia during head and neck examination. Gingival abnormalities, bleeding gums and oral mucosal pallor were the other findings on initial oral examination. Due to immunosuppression caused by the chemotherapy drugs oral mucosal ulcerations, uncontrolled herpes, candidiasis and pseudomoniasis were observed. 相似文献
7.
8.
9.
G Savini JD Dunsmore ID Robertson P Seneviratna 《Canadian Metallurgical Quarterly》1993,70(4):152-154
The Jamaican Perinatal Morbidity and Mortality Survey (1986-1987) revealed nine cases of a previously unreported form of birth-related injury in the English-speaking Caribbean--occipital osteodiastasis. Aspects of the clinical and pathological features of this form of occipital bone injury are presented and discussed. Our findings suggest that this lesion might occur more often than is currently accepted. 相似文献
10.
ID Zakharov AM Magasumov NI Simonova IaL E?del''man IuV Simenido 《Canadian Metallurgical Quarterly》1997,90(12):8-12
The authors present results of social and ecologic study carried out in Ufa. The results describe the course of ecologically important processes and phenomena in correlation with the public subjective understanding. Public health is influenced by hygienic parameters of food and water quality as well as a complex of social, economic and psychologic factors. Weak correlation between those parameters and ambient air pollution necessitates more accurate approach to ecologic mapping of cities and to manipulation with data on lower atmosphere pollution with chemical hazards. 相似文献