全文获取类型
收费全文 | 296篇 |
免费 | 7篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 30篇 |
金属工艺 | 3篇 |
机械仪表 | 5篇 |
建筑科学 | 9篇 |
能源动力 | 4篇 |
轻工业 | 20篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 8篇 |
一般工业技术 | 14篇 |
冶金工业 | 184篇 |
自动化技术 | 22篇 |
出版年
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2013年 | 3篇 |
2012年 | 2篇 |
2011年 | 6篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 9篇 |
2007年 | 9篇 |
2006年 | 12篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2000年 | 1篇 |
1999年 | 7篇 |
1998年 | 55篇 |
1997年 | 40篇 |
1996年 | 23篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 7篇 |
1976年 | 17篇 |
1975年 | 1篇 |
1973年 | 3篇 |
1965年 | 1篇 |
1956年 | 4篇 |
1954年 | 4篇 |
排序方式: 共有305条查询结果,搜索用时 875 毫秒
101.
The study was undertaken to test the significance of dummy use and carry-cots for counts of sudden infant death (SID). Based on the impression that very few SID victims have a dummy (comforter, pacifier) in their mouth at the time of death, and that a high proportion of SID babies were found dead in a carry-cot (portable crib, pram), a case-control study was performed. Questionnaires were sent to 167 parents of SID victims and to 352 parents of live-infants matched for sex and time of birth. Questionnaires were returned by 121 parents of SID victims (73%) and 307 parents of controls (87%). Only 4 SID victims (3%) were found dead with a dummy in their mouth. A quarter of the controls always used a dummy, 24% during night-time and 23% during daytime between 0 and 2 months of age, whereas this was only true for 10% in the SID group, the odds ratios being 0.27 for night-time and 0.36 for daytime. This trend was also seen until 1 year of life. Of the SID victims, 48% were found dead in a carry-cot, 79% during the cold time of the year and two thirds outdoors. Most deaths occurred during the afternoon (12 pm-5 pm). In both SID and control groups daytime use of carry-cots was equally frequent. Approximately 40% in both groups slept in such a cot between 5-7 days a week during the daytime. CONCLUSION: The use of dummy could be a favourable factor in the prevention of SID. Because of the frequent use of carry-cots during the daytime both in the SID group and the control group, the high percentage of SID in such cots does not seem to be of significance. However the high frequency of deaths in outdoor placed carry-cots during the cold period of the year may give clues to understanding the death mechanism in SID. 相似文献
102.
103.
JW Sleasman TO Harville GB White JF George DJ Barrett MM Goodenow 《Canadian Metallurgical Quarterly》1994,153(1):442-448
Human X-linked severe combined immunodeficiency disease (SCID) is an immunodeficiency disorder in which T cell development is arrested in the thymic cortex. B lymphocytes in children with X-linked SCID seem to differentiate normally. X-linked SCID is associated with a mutation in the gene that encodes the IL-2R gamma-chain. Because TCR-beta gene recombination is a pivotal initial event in T lymphocyte ontogeny within the thymus, we hypothesized that a failure to express normal IL-2R gamma could lead to impaired TCR-beta gene recombination in early thymic development. PCR was used to determine the status of TCR-beta gene-segment rearrangements in thymic DNA that had been obtained from children with X-linked SCID. The initial step in TCR-beta gene rearrangement, that of D beta to J beta recombination, was readily detected in all thymus samples from children with X-linked SCID; in contrast, V beta to DJ beta gene rearrangements were undetectable in the same samples. Both D beta to J beta and V beta to DJ beta TCR genes were rearranged in the thymic tissues obtained from immunologically normal children. We conclude that TCR beta-chain gene rearrangement is arrested in children with X-linked SCID. Our results suggest a causative relationship between the failure of TCR beta-chain gene rearrangements to proceed beyond DJ beta rearrangements and the production of a nonfunctional IL-2R gamma-chain. 相似文献
104.
TO Larsen K Frydenvang JC Frisvad C Christophersen 《Canadian Metallurgical Quarterly》1998,61(9):1154-1157
Fumiquinazoline F (1) and alantrypinone (2) have been isolated as the two major metabolites of Penicillium thymicola. The structure of 2, which contains a new ring structure, was elucidated by analysis of spectroscopic data including 2D NMR. The absolute configuration of 2 was established by a single-crystal X-ray diffraction study. 相似文献
105.
TO Cheng 《Canadian Metallurgical Quarterly》1997,96(10):3799-3800
106.
107.
J Cao M Drews HM Lee C Conner WF Bahou S Zucker 《Canadian Metallurgical Quarterly》1998,273(52):34745-34752
Activation of secreted latent matrix metalloproteinases (MMPs) is accompanied by cleavage of the N-terminal propeptide, thereby liberating the active zinc from binding to the conserved cysteine in the pro-domain. It has been assumed that an analogous mechanism is responsible for the activation of membrane type 1 MMP (MT1-MMP). Using recombinant wild-type MT1-MMP cDNA and mutant cDNAs transfected into COS-1 cells lacking endogenous MT1-MMP, we have examined the function of the propeptide domain of MT1-MMP. MT1-MMP was characterized by immunoblotting, surface biotinylation, gelatin substrate zymography, and 125I-tissue inhibitor of metalloproteinases 2 (TIMP-2) binding. In contrast to wild-type MT1-MMP-transfected COS-1 cells, transfected COS-1 cells containing a deletion of the N-terminal propeptide domain of MT1-MMP or a chimeric construction (substitution of the pro-domain of MT1-MMP with that of collagenase 3) were functionally inactive in terms of binding of 125I-labeled TIMP-2 to the cell surface and initiating the activation of pro-gelatinase A. These results support the concept that in its native plasma membrane-inserted form, the pro-domain of MT1-MMP plays an essential role in TIMP-2 binding and subsequent activation of pro-gelatinase A. 相似文献
108.
109.
RA Lothe M Hektoen H Johnsen GI Meling TI Andersen TO Rognum A Lindblom AL B?rresen-Dale 《Canadian Metallurgical Quarterly》1998,58(14):2923-2924
Recently, a T-to-A transversion creating an 8-base mononucleotide tract in the APC gene, resulting in substitution of lysine for isoleucine at codon 1307 (I1307K), was found in a subset of Ashkenazi Jews. This sequence variant was most frequent in colorectal cancer patients with a positive family history of colorectal cancer. To determine whether the I1307K variant plays a role in colorectal or breast cancer predisposition in the Norwegian population, we have analyzed blood samples from 210 colorectal cancer patients and 183 breast cancer patients by PCR and direct sequencing. Thirty-seven of the colorectal cancer patients had a positive family history of cancer. Among the breast cancer patients, 24 had a family history of colorectal cancer and 75 a family history of breast and/or ovarian cancer. Only one colorectal cancer patient who belonged to a Jewish family was found to carry the A variant. Our data show that the I1307K variant is rare in the Norwegian population and should not be viewed as a candidate for susceptibility testing for colorectal cancer. 相似文献
110.
Canada is a vast country with great diversity in its landscape, industry, culture and communities. The healthcare issues and concerns of people living in rural and remote areas are as fully diverse as the people and the landscape. This article describes the context of rural and remote nursing practice in Canada and discusses issues of health status and the social determinants of health, geographical isolation, professional isolation and cultural safety. It concludes with current initiatives in practice, education, research and policy. Particular issues facing nurses in rural and remote First Nations communities are highlighted. 相似文献