全文获取类型
收费全文 | 1243篇 |
免费 | 44篇 |
专业分类
电工技术 | 19篇 |
化学工业 | 144篇 |
金属工艺 | 16篇 |
机械仪表 | 25篇 |
建筑科学 | 47篇 |
矿业工程 | 4篇 |
能源动力 | 31篇 |
轻工业 | 139篇 |
水利工程 | 9篇 |
石油天然气 | 6篇 |
无线电 | 93篇 |
一般工业技术 | 226篇 |
冶金工业 | 344篇 |
原子能技术 | 16篇 |
自动化技术 | 168篇 |
出版年
2022年 | 12篇 |
2021年 | 13篇 |
2020年 | 7篇 |
2018年 | 13篇 |
2017年 | 26篇 |
2016年 | 23篇 |
2015年 | 18篇 |
2014年 | 23篇 |
2013年 | 79篇 |
2012年 | 39篇 |
2011年 | 48篇 |
2010年 | 52篇 |
2009年 | 32篇 |
2008年 | 38篇 |
2007年 | 30篇 |
2006年 | 28篇 |
2005年 | 21篇 |
2004年 | 27篇 |
2003年 | 31篇 |
2002年 | 30篇 |
2001年 | 16篇 |
2000年 | 25篇 |
1999年 | 24篇 |
1998年 | 90篇 |
1997年 | 45篇 |
1996年 | 42篇 |
1995年 | 24篇 |
1994年 | 22篇 |
1993年 | 19篇 |
1992年 | 18篇 |
1991年 | 11篇 |
1989年 | 7篇 |
1988年 | 12篇 |
1987年 | 16篇 |
1986年 | 16篇 |
1985年 | 23篇 |
1984年 | 14篇 |
1983年 | 19篇 |
1982年 | 15篇 |
1981年 | 22篇 |
1980年 | 18篇 |
1979年 | 7篇 |
1978年 | 16篇 |
1977年 | 32篇 |
1976年 | 23篇 |
1975年 | 17篇 |
1974年 | 19篇 |
1973年 | 21篇 |
1972年 | 14篇 |
1971年 | 8篇 |
排序方式: 共有1287条查询结果,搜索用时 0 毫秒
91.
92.
RG Owen RJ Johnson PA Evans GM Smith JA Child GJ Morgan 《Canadian Metallurgical Quarterly》1995,16(6):831-834
We have used a fluorescently based PCR technique to detect rearrangements in the immunoglobulin heavy chain (IgH) gene in the presentation BM of five patients with adult ALL and have looked for similar rearrangements in their PBPC. Using this approach we have been able to demonstrate clonal rearrangements in the PBPC of two of five patients. Remission BM samples taken 6-12 weeks prior to leucapheresis failed to show a clonal rearrangement in either patient. The significance of these results is discussed. 相似文献
93.
The prevalence of human immunodeficiency virus (HIV) in male prisoners in South Australia from July 1989 to June 1994 was ascertained from a repeated cross-sectional study. We also compared the criminological and demographic characteristics and histories of drug use of 39 HIV-infected prisoners and a randomly selected sample of 86 uninfected prisoners admitted at the same time. The numbers of HIV-infected prisoners in prison in any month ranged from 4 to 12. Prevalence among the total prison population ranged from 0.4 per cent to 1.4 per cent, and among the subpopulation of injecting drug users from 1.25 per cent to 4.36 per cent. Many HIV-infected prisoners continued after their diagnosis to have lifestyles that resulted in imprisonment. Infected prisoners were significantly older, had spent longer in prison and were more likely to be users of heroin (OR = 13.1) and methadone (OR = 25.4) than controls. Infection with HIV among South Australian prisoners has been continuous since at least the mid-1980s. The recidivism among many of the infected prisoners contributes to the variation in prevalence but also raises concerns about their management. Greater effort to minimise the recidivism of the HIV-infected prisoners could reduce the prevalence of HIV in the prison population. 相似文献
94.
The Rebinder effect, an environment-caused variation in the hardness of rock, ceramic, or glass, was investigated in polycrystalline aluminum oxide using conventional microhardness and electrochemical techniques. For an environment of pH-adjusted distilled water, both hardness and zeta potential were found to vary with pH. Maximum hardness and zero zeta potential were found to occur at pH 9.5. Observations in this study are consistent with a mechanism for the Rebinder effect in which changes in surface charge influence near-surface plastic deformation of surfaces and, thereby, hardness. 相似文献
95.
The authors determined the effects of distraction of the spine on physiologic integrity of the spinal cord using neurogenic motor evoked potentials (NMEPs), somatosensory evoked potentials (SEPs), spinal cord blood flow measurements, and clinical status in nine hogs. Spinal cord blood flow was measured after each level of distraction using the hydrogen washout technique. The results indicated that blood flow of at least 65% of baseline was required to maintain physiologic integrity of the spinal cord, and that a decrease of blood flow to 12% of baseline was associated with paraplegia. Neurogenic motor evoked potentials always correlated with the animal's postsurgical clinical status, whereas the SEP was falsely negative in one animal. 相似文献
96.
97.
Carey Michael P.; Kelley Mary L.; Buss Ray R.; Scott W. Owen 《Canadian Metallurgical Quarterly》1986,54(3):320
Developed an adolescent activities checklist (AAC) consisting of 100 items that assess pleasant and unpleasant activities. In an initial study with 151 8th–12th graders, the AAC subscales demonstrated high internal consistency and homogeneity. In a validation study conducted on 145 Ss, Unpleasant Activities total scores were correlated with Beck Depression Inventory (BDI) scores and with the Pleasant Activities total scores. Analysis of Ss with extreme BDI scores indicated differences on Unpleasant but not on Pleasant Activities total scores. The AAC appears to be a reliable index of the frequency of pleasant and unpleasant activities reported by adolescents. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
98.
99.
Natalie Stoeckl Michelle Esparon Marina Farr Aurélie Delisle Owen Stanley 《Papers in Regional Science》2014,93(4):783-801
This empirical study explores financial links between indigenous and non‐indigenous economic systems in a remote river catchment in Northern Australia (the Mitchell). It finds evidence of a profound and asymmetric ‘disconnect’ between these economies: an exogenous increase in indigenous incomes raises the incomes of non‐indigenous people, but the reverse is not true. Evidently, those seeking to improve the incomes of indigenous people in Northern Australia cannot simply seek to (i) increase payments to indigenous people, or (ii) expand the non‐indigenous sector hoping that some benefits will ‘trickle down’. Instead, structural change is required. 相似文献
100.
Rykaczewski K Hildreth OJ Wong CP Fedorov AG Scott JH 《Advanced materials (Deerfield Beach, Fla.)》2011,23(5):659-663
A process that allows control over the 3D motion of catalyst nanostructures during metal-assisted chemical etching by their local pinning prior to etching is demonstrated. The pinning material acts as a fulcrum for rotation of the catalyst structures resulting in etching of silicon features with rotational geometry. 相似文献