全文获取类型
收费全文 | 9418篇 |
免费 | 28篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 9篇 |
综合类 | 7篇 |
化学工业 | 177篇 |
金属工艺 | 14篇 |
机械仪表 | 9篇 |
建筑科学 | 37篇 |
矿业工程 | 2篇 |
能源动力 | 34篇 |
轻工业 | 123篇 |
水利工程 | 5篇 |
石油天然气 | 6篇 |
武器工业 | 1篇 |
无线电 | 69篇 |
一般工业技术 | 113篇 |
冶金工业 | 8735篇 |
原子能技术 | 8篇 |
自动化技术 | 100篇 |
出版年
2022年 | 13篇 |
2021年 | 18篇 |
2020年 | 15篇 |
2019年 | 12篇 |
2018年 | 21篇 |
2017年 | 17篇 |
2016年 | 13篇 |
2015年 | 7篇 |
2014年 | 21篇 |
2013年 | 46篇 |
2012年 | 38篇 |
2011年 | 22篇 |
2010年 | 25篇 |
2009年 | 20篇 |
2008年 | 27篇 |
2007年 | 32篇 |
2006年 | 39篇 |
2005年 | 34篇 |
2004年 | 32篇 |
2003年 | 33篇 |
2002年 | 25篇 |
2001年 | 19篇 |
2000年 | 26篇 |
1999年 | 300篇 |
1998年 | 2757篇 |
1997年 | 1527篇 |
1996年 | 979篇 |
1995年 | 566篇 |
1994年 | 439篇 |
1993年 | 549篇 |
1992年 | 73篇 |
1991年 | 109篇 |
1990年 | 111篇 |
1989年 | 92篇 |
1988年 | 110篇 |
1987年 | 102篇 |
1986年 | 104篇 |
1985年 | 82篇 |
1984年 | 14篇 |
1983年 | 16篇 |
1982年 | 50篇 |
1981年 | 48篇 |
1980年 | 91篇 |
1979年 | 19篇 |
1978年 | 21篇 |
1977年 | 198篇 |
1976年 | 456篇 |
1975年 | 19篇 |
1960年 | 5篇 |
1955年 | 8篇 |
排序方式: 共有9449条查询结果,搜索用时 0 毫秒
81.
82.
83.
84.
85.
The purpose of this study was to investigate self-disclosure, emotion-focused, and problem-focused coping styles among men with borderline hypertension and two groups of normotensive men differentiated by parental hypertension. Because blood pressure reactivity may discriminate between hypertensive and normotensive men, subjects in these three groups were categorized as high or low cardiovascular reactors based on their blood pressure response to a mental arithmetic task. Self-disclosure and coping styles were investigated in relation to status effects within the doctor-patient relationship. Men with exaggerated blood pressure reactivity were less self-disclosive and used fewer emotion-focused coping strategies than men with no blood pressure reactivity. Normotensives with a history of parental hypertension were less self-disclosive than normotensives without a history of parental hypertension. 相似文献
86.
87.
88.
89.
H King MC McCulloch JA Barrie E Kyriakides CV Beechey BM Cattanach IR Griffiths 《Canadian Metallurgical Quarterly》1997,26(8):557-566
Animals with spontaneous mutations affecting myelin formation have provided useful information about the genetic and cellular mechanisms regulating normal and abnormal myelination. In this paper we describe a novel murine mutation termed hindshaker (hsh), which is inherited in an autosomal recessive manner. Affected mice are characterised by a variable tremor of the hind end which commences at about 2 weeks of age and largely disappears in animals older than 6 weeks. There is hypomyelination affecting predominantly the spinal cord, although the optic nerves and brain are involved to a much lesser degree. The defect of thinly myelinated and naked axons is maximal at 20 days of age and largely resolves with time so that in the adult most axons are myelinated. The myelin structure appears normal and immunostains for the major proteins. Although the distribution of oligodendrocytes in the spinal cord is similar to normal during the period of hypomyelination, there are fewer mature cells. The hsh mutation appears to delay the maturation of oligodendrocytes, particularly in the spinal cord. Additionally, there is a considerable variation in phenotypic expression and in penetrance when the mutation is expressed on different genetic backgrounds, suggesting the hsh locus is subject to the influence of modifying gene(s). Identification of the hsh gene should identify a factor important in the development of oligodendrocytes, particularly those in the spinal cord. 相似文献
90.
We have sequenced the NIb coding region of sugarcane mosaic potyvirus strain SC (SCMV-SC) and eight field isolates of SCMV from Australia. This region comprised 1563 nucleotides and encoded a putative protein of 521 amino acids containing the consensus motif GDD. The protease cleavage sites between the NIa/NIb and the NIb/coat protein were found to be Q/C and Q/A, respectively. The SCMV sequences were most similar to sorghum mosaic potyvirus with identities of 70% and 78% at the nucleotide and amino acid levels, respectively. When the sequences were compared to each other, there was a maximum of 3.3% variation between isolates at the nucleotide level and a maximum of 0.8% at the amino acid level. Phylogenetic analysis of the sequences indicated the field isolates were grouped according to their geographical location. The SCMV sequence with most homology to all other isolates has been selected to generate constructs for replicase-mediated resistance. 相似文献