全文获取类型
收费全文 | 3986篇 |
免费 | 3篇 |
专业分类
化学工业 | 38篇 |
金属工艺 | 2篇 |
机械仪表 | 2篇 |
建筑科学 | 3篇 |
矿业工程 | 1篇 |
能源动力 | 6篇 |
轻工业 | 6篇 |
石油天然气 | 3篇 |
无线电 | 5篇 |
一般工业技术 | 13篇 |
冶金工业 | 3890篇 |
原子能技术 | 7篇 |
自动化技术 | 13篇 |
出版年
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 4篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2010年 | 5篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 4篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 9篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 109篇 |
1998年 | 1166篇 |
1997年 | 709篇 |
1996年 | 451篇 |
1995年 | 221篇 |
1994年 | 226篇 |
1993年 | 216篇 |
1992年 | 18篇 |
1991年 | 45篇 |
1990年 | 40篇 |
1989年 | 42篇 |
1988年 | 33篇 |
1987年 | 44篇 |
1986年 | 52篇 |
1985年 | 35篇 |
1984年 | 1篇 |
1983年 | 14篇 |
1982年 | 18篇 |
1981年 | 26篇 |
1980年 | 50篇 |
1979年 | 3篇 |
1978年 | 10篇 |
1977年 | 113篇 |
1976年 | 259篇 |
1975年 | 7篇 |
1964年 | 1篇 |
1955年 | 5篇 |
1954年 | 2篇 |
1934年 | 1篇 |
排序方式: 共有3989条查询结果,搜索用时 0 毫秒
71.
72.
73.
FS Chen PE Di Cesare AA Kale JF Lee VH Frankel SA Stuchin JD Zuckerman 《Canadian Metallurgical Quarterly》1998,13(8):867-873
We have developed a computer program for the rapid assessment of the primary structure differences between a protein of unknown sequence and a homologous known protein. Both proteins are reduced, alkylated, and digested with the same hydrolytic agent. The unfractionated peptide mixtures are submitted to automatic sequence analysis. Based on the knowledge of the reference sequence, the program utilizes the analysis data to identify all the potential peptides present in the two mixtures, determining their primary structure, homology degree, and molecular weight calculated both as integer MH+ and average mass variables. These fingerprints allow the user to easily identify the structural differences between the two proteins and clarify possible doubts by a mass spectrometric analysis of the two mixtures. In order to verify the utility of the program, we provide an application example using the already reported data of two homologous proteins. 相似文献
74.
C Bode SR Hanson JF Schmedtje E Haber P Mehwald AB Kelly LA Harker MS Runge 《Canadian Metallurgical Quarterly》1997,95(4):800-804
BACKGROUND: Inhibition of thrombin by either the indirect thrombin inhibitor heparin or by more potent direct thrombin inhibitors such as hirudin reduces thrombus formation after arterial injury. The present study was designed to determine if a fibrin-specific thrombin inhibitor could, by local thrombin inhibition, prevent thrombosis more effectively. METHODS AND RESULTS: We first studied antithrombotic potency in vitro, comparing fibrin-targeted hirudin (recombinant hirudin covalently linked to the Fab' fragment of the anti-fibrin monoclonal antibody 59D8) to recombinant hirudin in baboon plasma. Fibrin-targeted hirudin was nine times more effective than recombinant hirudin in inhibiting fibrin deposition on experimental clot surfaces in baboon plasma (P < .01). The potency of fibrin-targeted hirudin was then compared with that of recombinant hirudin in a baboon model of thrombus formation. 111In-labeled platelet deposition was measured in a synthetic graft segment of an extracorporeal arteriovenous shunt in control animals and in animals receiving either fibrin-targeted hirudin or hirudin. In these experiments, fibrin-targeted hirudin was 10-fold more potent than hirudin in inhibiting platelet deposition and thrombus formation (P < .05). CONCLUSIONS: These data indicate that targeting a thrombin inhibitors such as hirudin to an epitope present in thrombi results in increased antithrombotic potency. 相似文献
75.
Synthesis and Characterization of Pyridine Compounds for Amperometric Measurements of Leukocyte Esterase 下载免费PDF全文
Douglas Hanson Travis Menard Teresa Blazek Prof. Dr. Stanton McHardy Prof. Dr. Waldemar Gorski 《Chembiochem : a European journal of chemical biology》2018,19(14):1488-1491
We introduce a new class of substrates (compounds I – III ) for leukocyte esterase (LE) that react with LE yielding anodic current in direct proportion to LE activity. The kinetic constants Km and kcat for the enzymatic reactions were determined by amperometry at a glassy carbon electrode. The binding affinity of I – III for LE was two orders of magnitude better than that of existing optical LE substrates. The specificity constant kcat/Km was equal to 2.7, 3.8, and 5.8×105 m ?1 s?1 for compounds containing the pyridine ( I ), methoxypyridine ( II ), and (methoxycarbonyl)pyridine ( III ), respectively, thus showing an increase in catalytic efficiency in this order. Compound III had the lowest octanol/water partition coefficient (log p=0.33) along with the highest topological surface area (tPSA=222 Å2) and the best aqueous solubility (4.0 mg mL?1). The average enzymatic activity of LE released from a single leukocyte was equal to 4.5 nU when measured with compound III . 相似文献
76.
77.
Sidaty Naty Heulot Julien Hamidouche Wassim Pelcat Maxime Menard Daniel 《Multimedia Tools and Applications》2020,79(37-38):26861-26884
Multimedia Tools and Applications - With the explosive growth of mobile video consumption over the Internet, delivering video at high quality while controlling the energy consumption of embedded... 相似文献
78.
Ronald S. Cok John W. Hamer Christopher A. Bower Etienne Menard Salvatore Bonafede 《Journal of the Society for Information Display》2011,19(4):335-341
Abstract— Small integrated circuits of crystalline silicon (chiplets) transfer‐printed onto a flat‐panel‐display substrate provide greatly improved electrical performance and uniformity in active‐matrix organic light‐emitting‐diode (OLED) displays. The integrated circuits are formed in high‐performance crystalline silicon using conventional photolithographic processes and then transfer‐printed onto a substrate using a stamp that transfers hundreds or thousands of chiplets at once. The chiplets are connected to an external controller and to pixel elements using conventional photolithographic substrate processing methods. Active‐matrix OLED (AMOLED) displays using transfer‐printed chiplets have good yields, excellent uniformity, and electrical performance and are thermally robust. 相似文献
79.
R Fuhrer C Dufouil TC Antonucci MJ Shipley C Helmer JF Dartigues 《Canadian Metallurgical Quarterly》1999,149(2):116-126
The possible modifying effect of social relations on the association between depression and mortality was examined in a community-based cohort study. A total of 3,777 randomly selected persons 65 years of age and older in southwest France were followed over a 5-year period from 1988 in the Personnes Agees Quid (PAQUID). At study entry, the prevalence of elevated depressive symptomatology was 12.9% for men and 14.7% for women, and the reported relative isolation was 14.1% for men and 26.0% for women. During a total of 16,984 person-years of follow-up, 849 deaths occurred. Among participants with high levels of depressive symptomatology, the age-adjusted mortality rate ratio was 2.10 (95% confidence interval 1.7-2.7) in men and 1.76 (95% confidence interval 1.4-2.3) in women. When compared with individuals with the most connections, men and women with few social network connections were also at increased risk of mortality: age-adjusted rate ratio = 2.69 (95% confidence interval 1.9-3.8) for men and 1.56 (95% confidence interval 1.0-2.4) for women. Satisfaction with social support had a small but nonsignificant effect on mortality risk. For women, the excess risks due to depressive symptoms and few network connections are observed only in the 65- to 74-year age group, after adjusting for health and health behaviors. Social relations did not significantly modify the depression-mortality associations for either men or women, although the depression-mortality effect was reduced by 12.8% in men. The latter findings do not appear to be compatible with the buffering hypothesis, whereby we would expect social relations to decrease the depression-mortality association. Nonetheless, there are independent effects from these two factors, and older men who are depressed and not socially connected are at increased risk of dying earlier. 相似文献
80.