全文获取类型
收费全文 | 1458篇 |
免费 | 2篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 33篇 |
金属工艺 | 5篇 |
机械仪表 | 5篇 |
建筑科学 | 20篇 |
能源动力 | 3篇 |
轻工业 | 19篇 |
武器工业 | 1篇 |
无线电 | 27篇 |
一般工业技术 | 28篇 |
冶金工业 | 1288篇 |
原子能技术 | 3篇 |
自动化技术 | 24篇 |
出版年
2022年 | 2篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 7篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 12篇 |
2007年 | 5篇 |
2006年 | 15篇 |
2005年 | 8篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 46篇 |
1998年 | 413篇 |
1997年 | 254篇 |
1996年 | 164篇 |
1995年 | 75篇 |
1994年 | 61篇 |
1993年 | 89篇 |
1992年 | 15篇 |
1991年 | 17篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 14篇 |
1986年 | 15篇 |
1985年 | 15篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 4篇 |
1978年 | 10篇 |
1977年 | 19篇 |
1976年 | 57篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1970年 | 2篇 |
1960年 | 1篇 |
1955年 | 1篇 |
1932年 | 1篇 |
排序方式: 共有1460条查询结果,搜索用时 15 毫秒
61.
In a prospective study at a single centre between August 1995 and March 1996, 193 patients with elbow injuries were studied. Standard radiographs of the elbows were taken. A total of 181 X-rays were reported by one person concerning the presence or absence of fractures and fat-pad signs. The radiographs were analysed and positive predictive values were calculated for the presence of the fat-pad sign with radial head/neck fractures. The sensitivity for radial head/neck fracture is 85.4 per cent, while the specificity is only 50 per cent. The fat-pad sign must be used cautiously as an indicator of radial head/neck fractures; its absence is a more reliable indicator of the absence of a radial head/ neck fracture. 相似文献
62.
63.
In studies of T cell responses to synthetic peptides we have observed agonist and antagonist activities associated with contaminants identified within the parent synthesis. The synthesis of two candidate analogues implied by a peptide contaminant formed during the synthesis of La 51-58 (IMIKFNRL) has been carried out. The peptide contaminant was 17-18 Da smaller than the parent peptide consistent with a modified asparagine residue at position 6 and so we synthesised both an aspartimide and a nitrile analogue, representing cyclisation or dehydration of the asparagine residue. The candidate aspartimide and nitrile analogues both bound empty MHC class I molecules to form allo determinants recognised by monoclonal antibodies. These results demonstrate that altered synthetic peptides can bind class I MHC molecules and prompt caution in the use of synthetic peptides as a source of immunising antigen. 相似文献
64.
The work of adhesion, depending solely on the contact angle and surface tension, is unreliable as a guide to the strength of a joint. The kinetics of joint formation, exemplified by the rate of wetting, is also important and can be measured by rate of change of contact angle, a process for which an empirical equation has previously been suggested. A proposed mechanism introduces a viscosity term into the differential form of this equation.
A series of metal lacquers was prepared from epoxy, U/F and M/F resins in various ratios and also epoxy/P/F and epoxy/acrylic mixtures. Stainless steel substrates, coated with these lacquers were then cemented together using polyethylene as an adhesive. It is shown that joint strength correlates better with a high wetting constant (γ/ηL) than with a low contact angle except where this is very low. 相似文献
A series of metal lacquers was prepared from epoxy, U/F and M/F resins in various ratios and also epoxy/P/F and epoxy/acrylic mixtures. Stainless steel substrates, coated with these lacquers were then cemented together using polyethylene as an adhesive. It is shown that joint strength correlates better with a high wetting constant (γ/ηL) than with a low contact angle except where this is very low. 相似文献
65.
66.
67.
Similar depressions in growth were observed when rats consumed a 10% casein basal diet containing equal quantities of either methionine or S-methyl-L-cysteine. Supplemental glycine or serine partially alleviated the growth depression caused by the high levels of methionine but were ineffective in alleviating the growth depression caused by high levels of S-methylcysteine. Histological examination of five organs of rats fed the basal, high methionine or high S-methylcysteine diet for 6, 13 or 20 days revealed that only the spleens were affected in that there was erythrocyte engorgement and an accumulation of hemosiderin. The intensity of iron staining in spleens decreased from the second to the third week. The similarity in the depression of growth and splenic damage observed in rats consuming high levels of methionine or S-methylcysteine is consistent with an earlier suggestion that metabolism of the methionine or S-methylcysteine is consistent with an earlier suggestion that metabolism of the methyl group is in some way involved in the toxicity of methionine. 相似文献
68.
A system for the quantitative assessment of uterine activity during an oxytocin-induced labour has been developed. This has been achieved using relatively simple analogue techniques and can easily be used in the labour ward alongside existing monitoring equipment. Initial results indicate that a plateau of uterine activity can be easily recognised from the display and maintained at oxytocin dosage levels below those that might normally be used. 相似文献
69.
Common region of ALL-1 gene disrupted in epipodophyllotoxin-related secondary acute myeloid leukemia
CA Felix NJ Winick M Negrini WP Bowman CM Croce BJ Lange 《Canadian Metallurgical Quarterly》1993,53(13):2954-2956
Translocations at chromosomal band 11q23 characterize most de novo acute lymphoblastic leukemias (ALL) of infants, acute myeloid leukemias (AML) of infants and young children, and secondary AMLs following epipodophyllotoxin exposure. The chromosomal breakpoints at 11q23 have been cloned from isolated cases of de novo ALL and AML. Using an 859-base pair BamHI fragment of human ALL-1 complementary DNA that recognizes the genomic breakpoint region for de novo ALL and AML, we investigated two cases of secondary AML that followed etoposide-treated primary B-lineage ALL. In the first case, the translocation occurred between chromosomes 9 and 11 and the breakpoint at 11q23 localized to the same 9-kilobase region of the ALL-1 gene that is disrupted in most of the de novo leukemias. In the second case the translocation was between chromosomes 11 and 19. The breakpoint occurred outside of the ALL-1 breakpoint cluster region. 相似文献
70.
Niederer SA Kerfoot E Benson AP Bernabeu MO Bernus O Bradley C Cherry EM Clayton R Fenton FH Garny A Heidenreich E Land S Maleckar M Pathmanathan P Plank G Rodríguez JF Roy I Sachse FB Seemann G Skavhaug O Smith NP 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2011,369(1954):4331-4351
Ongoing developments in cardiac modelling have resulted, in particular, in the development of advanced and increasingly complex computational frameworks for simulating cardiac tissue electrophysiology. The goal of these simulations is often to represent the detailed physiology and pathologies of the heart using codes that exploit the computational potential of high-performance computing architectures. These developments have rapidly progressed the simulation capacity of cardiac virtual physiological human style models; however, they have also made it increasingly challenging to verify that a given code provides a faithful representation of the purported governing equations and corresponding solution techniques. This study provides the first cardiac tissue electrophysiology simulation benchmark to allow these codes to be verified. The benchmark was successfully evaluated on 11 simulation platforms to generate a consensus gold-standard converged solution. The benchmark definition in combination with the gold-standard solution can now be used to verify new simulation codes and numerical methods in the future. 相似文献