全文获取类型
收费全文 | 423篇 |
免费 | 2篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 25篇 |
金属工艺 | 10篇 |
机械仪表 | 10篇 |
建筑科学 | 6篇 |
能源动力 | 5篇 |
轻工业 | 16篇 |
水利工程 | 4篇 |
石油天然气 | 3篇 |
无线电 | 26篇 |
一般工业技术 | 58篇 |
冶金工业 | 221篇 |
原子能技术 | 11篇 |
自动化技术 | 21篇 |
出版年
2021年 | 3篇 |
2020年 | 4篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2014年 | 4篇 |
2013年 | 9篇 |
2012年 | 11篇 |
2011年 | 7篇 |
2010年 | 9篇 |
2009年 | 7篇 |
2008年 | 15篇 |
2007年 | 9篇 |
2006年 | 12篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 13篇 |
2001年 | 12篇 |
2000年 | 3篇 |
1999年 | 17篇 |
1998年 | 46篇 |
1997年 | 40篇 |
1996年 | 15篇 |
1995年 | 13篇 |
1994年 | 7篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 8篇 |
1976年 | 21篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有425条查询结果,搜索用时 0 毫秒
371.
Hopthrow Timothy; Abrams Dominic; Frings Daniel; Hulbert Lorne G. 《Canadian Metallurgical Quarterly》2007,21(2):272
Alcohol is often consumed in group settings. The present article examines the effect of alcohol on intergroup competitiveness through the use of a prisoner's dilemma game. One hundred fifty-eight college students participated in the study, either individually or as a member of a 4-person experimental single-sex group. Participants consumed either alcohol (1.13 g ethanol/kg body weight) or a placebo. Results show no effect of alcohol on cooperative choice within individuals. However, groups were significantly less cooperative after consuming alcohol than they were after consuming a placebo. In addition, after consuming alcohol, groups were less cooperative than were individuals. Results are discussed in terms of the way alcohol may affect focus of attention on group-level cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
372.
Brisket disease in yearling feedlot cattle 总被引:1,自引:0,他引:1
R Jensen RE Pierson PM Braddy DA Saari A Benitez DP Horton LH Lauerman AE McChesney AF Alexander DH Will 《Canadian Metallurgical Quarterly》1976,169(5):515-517
During all of 1974, we surveyed, for illnesses and deaths, about 407,000 yearling feedlot cattle maintained at 1,600 m altitude. Of 1,988 cattle necropsied, 116 (5.8%) had brisket disease. The malady occurred during all seasons but was most common throughout fall and winter. The gross changes were hypertrophy and dilatation of the right ventricle and generalizaed passive congestion. The postulated causative factors were high genetic susceptibility, rapid growth rate, previous mountain grazing, and hypoventilation with airway hypoxia. 相似文献
373.
G. L. Powell J. S. Bullock IV R. L. Hallman P. J. Horton D. P. Hutchinson 《Journal of Fusion Energy》1990,9(3):355-357
Techniques have been established to prepare palladium specimens for cold fusion experiments using an ultra-high-vacuum, allmetal, high-temperature furnace to melt palladium metal in high purity alumina molds having a test tube shape. To date 6-mm and 15-mm cylinders have been fabricated, the latter being used to fabricate a sphere 12.5-mm in diameter. Techniques and facilities used for palladium-hydrogen isotope pressure-volume-temperature measurements1–4 have been used to anneal these palladium specimens after machining and, in some cases, to charge these specimens with deuterium to PdD0.63 stoichiometry prior to their use in electrochemical cells. The modeling of palladium-hydrogen isotope pressure-composition-temperature curves is described wherein existing data5,6 is used to derive models that accurately describe the existing data and that extrapolate to high compositions. Experiments for reacting6LiD with Pd rods at 700°C to 800°C, in an attempt to precharge6Li into the Pd rods, are being prepared.Operated for the U.S. Department of Energy by Martin Marietta Energy Systems, Inc. Under Contract no. DE-AC05-84OR21400. 相似文献
374.
375.
CM Horton 《Canadian Metallurgical Quarterly》1998,97(3):36-37
Four stages of the basal compartment disorders, not revealed while histological investigation and which may be used as an early differential-diagnostic, prognostic signs for the choice of the patients treatment tactics, were displayed during analysis of 20 observations of recurrent junction cell papilloma and 8 bladder cancer in situ. 相似文献
376.
B Horton 《Canadian Metallurgical Quarterly》1993,61(1):25-31
The formation of germ cells, their progress through meiosis, and the earliest stages of development are times when the genes in normal organisms are in balanced conflict. One conflict is expressed as meiotic drive, a system which characteristically associated with low fertility. It is argued that the association between carcinoma in situ (CIS) and low fertility can be explained by assuming that some meiotic drive system is operating in the testis. In meiotic drive systems, single haploid sets of chromosomes are frequently prevented from contributing to the next generation. The progression of carcinoma in situ to the near triploidy of germ cell tumors is taken as supportive evidence that meiotic drive systems are operating during tumor formation. Another conflict system is the opposing interests of the genes inherited from each parent. In general, genes inherited from the father promote growth and those from the mother limit the growth of the normal conceptus. In germ cell tumors, it is not known if the chromosomes retain a memory of their parent. 相似文献
377.
RG Allen BP Keogh M Tresini GS Gerhard C Volker RJ Pignolo J Horton VJ Cristofalo 《Canadian Metallurgical Quarterly》1997,272(40):24805-24812
We determined the activities of NADH dehydrogenase (ND), succinate dehydrogenase, and cytochrome c oxidase (COX) in 29 skin fibroblast lines established from donors ranging in age from 12 gestational weeks to 94 years. The results of this study demonstrate that all three of the enzyme activities examined are greater in adult-derived fibroblasts than in the fetal cell lines. The ratio of enzyme activities that control electron entry into and exit from the electron transport chain varied directly with lucigenin-detected chemiluminescence (an indicator of .O2- generation) and inversely with H2O2 generation. These results indicate a clear difference in the predominant oxidant species generated during fetal and adult stages of life. We also examined the mRNA abundances of different components of the electron transport chain complexes. We observed higher abundances of mitochondrial encoded mRNAs (COX 1 and ND 4) in cell lines established from adults than in fetal cells. No differences in the mRNA abundances of the nuclear encoded sequences (COX 4 and ND 51) were observed in fetal and postnatal-derived lines. Succinate dehydrogenase mRNA abundance was greater in cell lines established from postnatal donors than in fetal cell lines. No significant differences between cell lines established from young and old adults were detected in any of the parameters examined. 相似文献
378.
Spanos Nicholas P.; Bertrand Lorne D.; Perlini Arthur H. 《Canadian Metallurgical Quarterly》1988,97(3):378
Wilson and Kihlstrom (1986) reported that hypnotic amnesia was not associated with reduced clustering when subjects had initially learned a long (16-item) list of categorized words. However, Wilson and Kihlstrom inappropriately substituted hypnotic susceptibility for level of amnesia in their analyses and, consequently, they failed to test for an association between reduced clustering and amnesia. Furthermore, supplementary correlational findings provided by Wilson and Kihlstrom strongly suggest that a disorganized clustering effect occurred but went unrecognized in their data. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
379.
A Veves R Saouaf VM Donaghue CA Mullooly JA Kistler JM Giurini ES Horton RA Fielding 《Canadian Metallurgical Quarterly》1997,46(11):1846-1852
The aim of the present study was to examine if diabetes in the absence of neuropathy affects the exercising capacity of IDDM patients, and whether regular, intense training has a beneficial effect on endothelial function. Five groups of subjects were studied: 23 healthy control subjects who exercised regularly (age 33 +/- 6 years), 23 nonneuropathic type 1 diabetic patients who exercised regularly (age 33 +/- 6 years, IDDM duration 11 +/- 8 years), 7 neuropathic type 1 diabetic patients who exercised regularly (age 36 +/- 7 years, IDDM duration 22 +/- 8 years), 18 healthy subjects who did not exercise regularly (age 34 +/- 7 years), and 5 nonneuropathic type 1 diabetic patients who did not exercise regularly (age 31 +/- 4 years, IDDM duration 20 +/- 3 years). All groups were matched for age, sex, and body weight. No differences existed in the energy expenditure per week in physical activity among the three exercising groups or between the two nonexercising groups. The maximal oxygen uptake was similar between control and diabetic nonneuropathic exercisers, and among diabetic neuropathic exercisers, control nonexercisers, and diabetic nonexercisers; however, a significant difference existed between the first two and the last three groups (P < 0.0001). A stepwise increase was found in the resting heart rate among the groups, ranging from the lowest in control exercisers to the highest in diabetic nonexercisers, but the maximal heart rate was lower only in diabetic neuropathic exercisers compared with all other groups (P < 0.05). Assessments of endothelial function in both macro- and microcirculation were performed in 12 control exercisers, 10 diabetic nonneuropathic exercisers, 5 diabetic neuropathic exercisers, 17 control nonexercisers, and 4 diabetic nonexercisers. When all diabetic patients were considered as one group and all control subjects as another, the microcirculation endothelial function in the diabetic group was reduced compared with the control subjects (91 +/- 49 vs. 122 +/- 41% flux increase over baseline; P < 0.05). In contrast, no differences existed among the three diabetic groups or between the two control groups. Similarly, in macrocirculation, a reduced response during reactive hyperemia was observed in the diabetic patients compared with control subjects (7.0 +/- 4.5 vs. 11.2 +/- 6.6% diameter increase; P < 0.05), whereas again no difference existed among the three diabetic groups or between the two control groups. These data suggest that diabetes per se does not affect aerobic exercise capacity (VO2max) in physically active individuals, but is reduced in the presence of neuropathy. In addition, regular exercise training involving the lower extremities does not improve the endothelial function in the micro- and macrocirculation of the nonexercised upper extremity in type 1 diabetic patients. 相似文献
380.
Carcinogenesis is a stepwise process that occurs through mutations of cancer-related genes. Five or more genes must be mutated before malignant transformation occurs in most adult cancers; in some childhood cancers as few as two mutated genes may be sufficient. A rare inherited mutation of a critical gene may predestine cancer to occur in one or more sites. This germline mutation is present in virtually every cell in the body, except half of the germ cells, which do not contain the mutated gene in their haploid chromosome set. These and other genes have been used to piece together a puzzle of regulatory systems that govern cell division and proliferation, as well as apoptosis or programmed cell death. Mutations of these genes result not only in increased cell proliferation but also in diminished cell death. Most genetic changes that occur during carcinogenesis are not inherited or germline. They are acquired after birth and are called somatic mutations. A somatic mutation affects only the mutated cell and its progeny. Each time a cell divides, there is a chance of somatic mutation, and therefore there always is a low, background risk for cancer and other malignant lesions. A far more prevalent cause of cancer-related death in the United States is environmental exposure. Such exposure causes somatic mutations of cancer-related genes through direct damage to DNA or through alteration of proliferation or cell death, which enhances the baseline risk for mutation. As carcinogenesis becomes understood, interventions may be designed that selectively interfere in important steps. Screening for cancer is based on the premise that one can treat a patient for a cancer that has not spread from its primary site. Nevertheless, cancer screening is controversial and often confusing. Issues of costs, risks versus benefits, physical time and effort, and patient compliance all affect the clinician's view of screening, often to the extent that the true value of this approach to cancer control is underappreciated and underutilized. A clinician should consider the following questions when assessing the priority, scope, and intensity of cancer screening. Is the cancer an important public health problem? Can preclinical stages be detected and cured? Are effective screening tests available? Are the tests feasible and acceptable? Have screening programs reduced cancer-specific mortality? Is the screening program cost effective? Is screening generally recommended? There is clear-cut evidence of benefit from screening for cancer of the cervix, breast, colon and rectum, and skin and some specific genetic syndromes. Evidence of survival benefit from screening for prostate cancer is lacking, although prostate specific antigen screening is widely used. Screening for lung and ovarian cancer is ineffective. 相似文献