全文获取类型
收费全文 | 1558篇 |
免费 | 24篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 15篇 |
综合类 | 4篇 |
化学工业 | 356篇 |
金属工艺 | 23篇 |
机械仪表 | 38篇 |
建筑科学 | 59篇 |
矿业工程 | 12篇 |
能源动力 | 45篇 |
轻工业 | 112篇 |
水利工程 | 18篇 |
石油天然气 | 6篇 |
无线电 | 101篇 |
一般工业技术 | 220篇 |
冶金工业 | 387篇 |
原子能技术 | 16篇 |
自动化技术 | 171篇 |
出版年
2022年 | 12篇 |
2021年 | 9篇 |
2018年 | 18篇 |
2017年 | 16篇 |
2016年 | 7篇 |
2015年 | 17篇 |
2014年 | 23篇 |
2013年 | 64篇 |
2012年 | 39篇 |
2011年 | 62篇 |
2010年 | 45篇 |
2009年 | 47篇 |
2008年 | 59篇 |
2007年 | 52篇 |
2006年 | 53篇 |
2005年 | 46篇 |
2004年 | 40篇 |
2003年 | 32篇 |
2002年 | 46篇 |
2001年 | 34篇 |
2000年 | 23篇 |
1999年 | 30篇 |
1998年 | 67篇 |
1997年 | 54篇 |
1996年 | 48篇 |
1995年 | 31篇 |
1994年 | 31篇 |
1993年 | 35篇 |
1992年 | 25篇 |
1991年 | 21篇 |
1990年 | 35篇 |
1989年 | 40篇 |
1988年 | 39篇 |
1987年 | 27篇 |
1986年 | 24篇 |
1985年 | 26篇 |
1984年 | 25篇 |
1983年 | 20篇 |
1982年 | 28篇 |
1981年 | 28篇 |
1980年 | 21篇 |
1979年 | 16篇 |
1978年 | 20篇 |
1977年 | 19篇 |
1976年 | 27篇 |
1975年 | 17篇 |
1974年 | 14篇 |
1973年 | 16篇 |
1972年 | 7篇 |
1971年 | 8篇 |
排序方式: 共有1583条查询结果,搜索用时 15 毫秒
11.
Three studies, involving 146 undergraduates and 68 heterosexual couples, assessed the construct validity of the self- and other-model dimensions underlying the 4-category model of adult attachment. Five methods were used to assess the hypothesized dimensions: self-reports, friend-reports, romantic partner reports, trained judges' ratings of peer attachment, and trained judges' ratings of family attachment. Study 2 related the latent attachment dimensions to theoretically relevant outcome latent variables. As predicted, Ss' self models converged with direct measures of the positivity of their self-concepts, and Ss' other models converged with direct measures of the positivity of their interpersonal orientations. Study 3 related the latent attachment dimensions to 3 alternate self-report measures of adult attachment and showed that the 2 dimensions served as an organizing framework for the different measurement approaches. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
12.
It was proposed that individuals' responses to information regarding their relative position in a performance distribution would depend on how they frame the information. To the degree that they focus selectively on the positive features of the feedback (i.e., the number of others who performed worse than them) rather than the negative features (i.e., the number of others who performed better than them) they should report higher ability levels and more positive affective reactions. In Study I, Ss received feedback indicating that they occupied a particular percentile standing in either a large or small distribution. Individuals with negative orientations (depressives and pessimists) reported lower ability levels as a function of increases in comparison group size, whereas individuals with positive orientations (nondepressives and optimists) reported higher ability levels. Presumably, these effects occurred because negatively oriented persons focused on the negative features of the feedback and positively oriented persons focused on the positive features of the feedback. The results of Study 2 support this explanation. Implications for the social comparison literature are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
13.
14.
Attempted to determine whether the order in which 2 counselors were presented on videotape would affect ratings of their performances. 70 participants (63 women and 7 men) randomly assigned to 2 groups viewed and rated counseling interviews conducted by C. Rogers and E. L. Shostrom. Groups differed only in the order of presentation of counselors. The resulting 2?×?2 split-plot factorial design had 1 between-Ss factor (order of presentation) and 1 within-S factor (counselor). A multivariate analysis of variance (MANOVA) yielded a statistically significant interaction, indicating that the order in which counselors were evaluated significantly affected the magnitude of ratings of their performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
15.
The issue of generic scaling laws able to adequately predict (within better than 20%) cratering in semi-infinite targets and perforations through finite thickness targets was revisited. The approach used was to apply physical logic for hydrodynamics in a consistent manner able to account for chunky-body impacts such that the only variables needed are those directly related to known material properties for both the impactor and target. The analyses were compared and verified versus CTH hydrodynamic code calculations and existing experimental data. Comparisons with previous scaling laws were also performed to identify which (if any) were good for generic purposes. This paper is a short synopsis of the full report [1] available through the NASA Langley Research Center, LDEF Science Office. 相似文献
16.
Liping Wang Ramana V. Grandhi Dale A. Hopkins 《International journal for numerical methods in engineering》1995,38(10):1721-1738
The objective of this paper is to conduct reliability-based structural optimization in a multidisciplinary environment. An efficient reliability analysis is developed by expanding the limit functions in terms of intermediate design variables. The design constraints are approximated using multivariate splines in searching for the optimum. The reduction in computational cost realized in safety index calculation and optimization are demonstrated through several structural problems. This paper presents safety index computation, analytical sensitivity analysis of reliability constraints and optimization using truss, frame and plate examples. 相似文献
17.
Mark T. Muldoon Dale V. Onisk Michael C. Brown & James W. Stave 《International Journal of Food Science & Technology》2004,39(8):851-861
Bovine spongiform encephalopathy (BSE), or ‘mad cow disease’, is one of several transmissable spongiform encephalopathies (TSEs) known to affect certain mammals and is spread through the ingestion of infected animal tissue. It is believed that the inadvertent contamination of meat and bone meal (MBM) with infected animal tissue and the subsequent use of this material as a feed supplement contributed to the spread of the disease in cattle. As a result, the use of processed animal proteins (PAPs) in animal feeds is regulated in many parts of the world. Although feed testing is the only definitive means to certify compliance, regulatory compliance often relies solely on paper certification. Recently, rapid methods have become available that can be used by regulators to determine compliance during routine inspections. We describe a rapid, immunochromatographic strip test that can detect 0.1% MBM in animal feed. The test takes 15 min to perform and large numbers of samples can be screened for PAPs simultaneously. 相似文献
18.
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
19.
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
20.