全文获取类型
收费全文 | 1223篇 |
免费 | 1篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 34篇 |
金属工艺 | 2篇 |
机械仪表 | 5篇 |
建筑科学 | 1篇 |
矿业工程 | 5篇 |
轻工业 | 4篇 |
水利工程 | 3篇 |
石油天然气 | 39篇 |
无线电 | 8篇 |
一般工业技术 | 57篇 |
冶金工业 | 1058篇 |
原子能技术 | 2篇 |
自动化技术 | 5篇 |
出版年
2017年 | 4篇 |
2013年 | 4篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2010年 | 2篇 |
2008年 | 2篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 26篇 |
1998年 | 317篇 |
1997年 | 157篇 |
1996年 | 118篇 |
1995年 | 65篇 |
1994年 | 71篇 |
1993年 | 71篇 |
1992年 | 9篇 |
1991年 | 23篇 |
1990年 | 15篇 |
1989年 | 18篇 |
1988年 | 24篇 |
1987年 | 14篇 |
1986年 | 15篇 |
1985年 | 14篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 21篇 |
1979年 | 6篇 |
1978年 | 11篇 |
1977年 | 32篇 |
1976年 | 57篇 |
1975年 | 10篇 |
1974年 | 7篇 |
1973年 | 5篇 |
1972年 | 9篇 |
1970年 | 4篇 |
1968年 | 2篇 |
1967年 | 4篇 |
1966年 | 4篇 |
1965年 | 4篇 |
1964年 | 2篇 |
1963年 | 3篇 |
1962年 | 2篇 |
1960年 | 4篇 |
1957年 | 2篇 |
排序方式: 共有1224条查询结果,搜索用时 15 毫秒
11.
S Rothemund M Beyermann E Krause G Krause M Bienert RS Hodges BD Sykes FD S?nnichsen 《Canadian Metallurgical Quarterly》1995,34(40):12954-12962
D-Amino acid replacements and the determination of resulting structural changes are a useful tool to recognize amphipathic helices in biologically active peptides such as neuropeptide Y and corticotropin-releasing factor. In this paper the secondary structures of one amphipathic alpha-helical peptide and its double D-amino acid analog have been determined by means of 1H NMR and CD spectroscopies under equivalent conditions. The chemical shifts (NH and C alpha H) and the analysis of nuclear Overhauser effects show a split of the continuous helix for the all-L peptide into two helices at the position of double D-amino acid replacement. Hydrogen exchange rates correlate with water accessibilities in the hydrophobic/hydrophilic face and confirm the amphipathic helical structure in the all-L peptide as well as in its double D-amino acid analog. A significantly accelerated hydrogen isotope exchange rate is observed for the D-Ala9 backbone proton, implying an increased flexibility at that position. These results show that the incorporation of an adjacent pair of D-amino acids only causes a local change in structure and flexibility, which makes the double D replacement interesting as a tool for specific helix-disturbing modifications to search for helical conformations in biologically active peptides. 相似文献
12.
13.
14.
M Albert C Athanassopoulos LB Auerbach D Bauer R Bolton B Boyd RL Burman I Cohen DO Caldwell BD Dieterle JB Donahue AM Eisner A Fazely FJ Federspiel GT Garvey RM Gunasingha V Highland J Hill R Imlay K Johnston WC Louis A Lu AK Mann J Margulies K McIlhany W Metcalf RA Reeder V Sandberg M Schillaci D Smith I Stancu W Strossman MK Sullivan GJ VanDalen W Vernon YX Wang DH White D Whitehouse D Works Y Xiao S Yellin 《Canadian Metallurgical Quarterly》1995,51(3):R1065-R1069
15.
16.
17.
H Wakasaki D Koya FJ Schoen MR Jirousek DK Ways BD Hoit RA Walsh GL King 《Canadian Metallurgical Quarterly》1997,94(17):9320-9325
Increased cardiovascular mortality occurs in diabetic patients with or without coronary artery disease and is attributed to the presence of diabetic cardiomyopathy. One potential mechanism is hyperglycemia that has been reported to activate protein kinase C (PKC), preferentially the beta isoform, which has been associated with the development of micro- and macrovascular pathologies in diabetes mellitus. To establish that the activation of the PKCbeta isoform can cause cardiac dysfunctions, we have established lines of transgenic mice with the specific overexpression of PKCbeta2 isoform in the myocardium. These mice overexpressed the PKCbeta2 isoform transgene by 2- to 10-fold as measured by mRNA, and proteins exhibited left ventricular hypertrophy, cardiac myocyte necrosis, multifocal fibrosis, and decreased left ventricular performance without vascular lesions. The severity of the phenotypes exhibited gene dose-dependence. Up-regulation of mRNAs for fetal type myosin heavy chain, atrial natriuretic factor, c-fos, transforming growth factor, and collagens was also observed. Moreover, treatment with a PKCbeta-specific inhibitor resulted in functional and histological improvement. These findings have firmly established that the activation of the PKCbeta2 isoform can cause specific cardiac cellular and functional changes leading to cardiomyopathy of diabetic or nondiabetic etiology. 相似文献
18.
19.
BD Weiss 《Canadian Metallurgical Quarterly》1994,13(1):175-186
Symptoms related to the bicycle seat are common among cyclists. Skin problems, such as chafing, ischial tuberosity pain, folliculitis, and ulceration are particularly common. Although rarely serious, these problems may cause significant discomfort and interfere with a cyclist's ability to ride. Numerous preventive measures have been recommended to prevent these problems, mostly related to seat position, seat construction, and bicycling pants. Little research is available, however, to support any of these recommendations. Research does indicate that use of skin creams is not effective for prevention of bicycle-related skin problems. 相似文献
20.
An approach to the calculation and design of metal forming is proposed and theoretically considered. This approach can minimize the nonuniformity of a deformation distribution over the cross section of ready products, which is equal to controlling the structure and properties of forged pieces. This approach is based on the calculation of the intermediate shapes of a forged piece by solving a set of inverse forming problems using the boundary element method and by constructing a forging process that is optimal according to a given criterion using dynamic programming. 相似文献