全文获取类型
收费全文 | 2444篇 |
免费 | 6篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 50篇 |
金属工艺 | 10篇 |
机械仪表 | 5篇 |
建筑科学 | 18篇 |
能源动力 | 3篇 |
轻工业 | 22篇 |
石油天然气 | 2篇 |
无线电 | 53篇 |
一般工业技术 | 48篇 |
冶金工业 | 2196篇 |
原子能技术 | 3篇 |
自动化技术 | 38篇 |
出版年
2022年 | 2篇 |
2020年 | 2篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 14篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 8篇 |
2007年 | 14篇 |
2006年 | 10篇 |
2005年 | 17篇 |
2004年 | 12篇 |
2003年 | 15篇 |
2002年 | 11篇 |
2001年 | 6篇 |
2000年 | 12篇 |
1999年 | 98篇 |
1998年 | 695篇 |
1997年 | 375篇 |
1996年 | 268篇 |
1995年 | 136篇 |
1994年 | 131篇 |
1993年 | 151篇 |
1992年 | 14篇 |
1991年 | 27篇 |
1990年 | 31篇 |
1989年 | 23篇 |
1988年 | 32篇 |
1987年 | 16篇 |
1986年 | 17篇 |
1985年 | 17篇 |
1984年 | 4篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 21篇 |
1979年 | 4篇 |
1978年 | 10篇 |
1977年 | 48篇 |
1976年 | 116篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1970年 | 2篇 |
1969年 | 3篇 |
1964年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有2450条查询结果,搜索用时 23 毫秒
61.
BJ Guglielmo 《Canadian Metallurgical Quarterly》1999,13(2):23-30
Antimicrobial agents are widely utilized in the prevention and treatment of infection in patients with cardiovascular diseases. Knowledge of spectrum of activity, pharmacology, adverse effect and toxicity profile, and emergence of resistant pathogens is critical to the appropriate use of these agents. The following review will emphasize the safe, effective use of antimicrobial drugs in the cardiovascular patient. 相似文献
62.
BJ Wilson 《Canadian Metallurgical Quarterly》1999,35(1):214-222
This study investigated the social deficits of developmentally delayed children. Participants were 48 five-year-old to eight-year-old boys. Delayed children (n = 20) were compared with nondelayed children of similar chronological age (CA nondelayed; n = 20) and of similar mental age (n = 8). The behavior and emotion regulation strategies of participants were assessed in an analogue entry situation. Delayed children were just as able as nondelayed children to understand the play themes of others but were more intrusive in delivering their entry attempts. Delayed children appeared to have less effective emotion regulation strategies for coping with entry failure and were more likely to increase their use of disruptive entry strategies over time than CA nondelayed children. 相似文献
63.
BJ Dave DL Pickering MM Hess DD Weisenburger JO Armitage WG Sanger 《Canadian Metallurgical Quarterly》1999,108(2):120-126
Our laboratories have documented a significantly high occurrence of chromosome 1p36 rearrangements in non-Hodgkin lymphoma (NHL). The cell division cycle 2-like 1(CDC2L1) (also known as TP58 or PITSLRE) gene, a protein kinase implicated in apoptotic signaling, is located at the very distal region of chromosome 1p36 and is likely to be disrupted by structural rearrangements involving 1p36. To determine the molecular consequences of the recurrent involvement of the 1p36 region, we examined metaphases containing 1p36 abnormalities from 31 specimens derived from 26 patients for the possible deletion of CDC2L1 by fluorescence in situ hybridization (FISH) using the TP58clk-1 DNA probe. Twenty-three cases exhibited the loss of CDC2L1 from the abnormal chromosome 1. In 2 of 26 cases, the gene locus was translocated to the partner chromosome, and in four specimens, all derived from one case, CDC2L1 was not deleted. This pilot investigation suggests that 1p36 rearrangements, and consequently the loss of the CDC2L1 gene locus, is important in NHL. This work also opens avenues for further molecular studies and prognostic correlations. 相似文献
64.
We describe a glucose sensor based on a mutant glucose/galactose binding protein (GGBP) and phase-modulation fluorometry. The GGBP from Escherichia coli was mutated to contain a single cysteine residue at position 26. When labeled with a sulfhydryl-reactive probe 2-(4'-iodoacetamidoanilino)naphthalene-6-sulfonic acid, the labeled protein displayed a twofold decrease in intensity in response to glucose, with a dissociation constant near 1 microM glucose. The ANS-labeled protein displayed only a modest change in lifetime, precluding lifetime-based sensing of glucose. A modulation sensor was created by combining ANS26-GGBP with a long-lifetime ruthenium (Ru) metal-ligand complex on the surface of the cuvette. Binding of glucose changed the relative intensity of ANS26-GGBP and the Ru complex, resulting in a dramatic change in modulation at a low frequency of 2.1 MHz. Modulation measurements at 2.1 MHz were shown to accurately determine the glucose concentration. These results suggest an approach to glucose sensing with simple devices. 相似文献
65.
66.
Classroom peer acceptance, friendship, and victimization: distinct relational systems that contribute uniquely to children's school adjustment? 总被引:1,自引:0,他引:1
The proposition that relationships make differential (i.e., unique, redundant, contingent) contributions to adjustment was examined by investigating the linkages between children's participation in different types of peer relationships (i.e., friendship, peer acceptance, peer victimization) and their adjustment to school. Relationship measures were gathered for 5- to 6-year-old children (105 males, 95 females) twice during kindergarten (i.e., fall and spring) and were correlated with adjustment indicators at each time of assessment and used to predict changes in school adjustment over time. Examination of the relative associations between the relationship measures and children's adjustment revealed evidence of both unshared (i.e., unique) and shared (i.e., redundant) linkages, depending on the form of adjustment examined. These findings suggest that adjustment may be influenced by the diverse experiences (i.e., provisions) that children encounter in different forms of relationship, and that certain types of relationships may have greater or lesser adaptive significance depending on the adjustment outcome examined. 相似文献
67.
The management of hypertrophic cardiomyopathy 总被引:1,自引:0,他引:1
68.
RL Cifelli JI Kirkland A Weil AL Deino BJ Kowallis 《Canadian Metallurgical Quarterly》1997,94(21):11163-11167
A densely sampled, diverse new fauna from the uppermost Cedar Mountain Formation, Utah, indicates that the basic pattern of faunal composition for the Late Cretaceous of North America was already established by the Albian-Cenomanian boundary. Multiple, concordant 40Ar/39Ar determinations from a volcanic ash associated with the fauna have an average age of 98.39 +/- 0.07 million years. The fauna of the Cedar Mountain Formation records the first global appearance of hadrosaurid dinosaurs, advanced lizard (e.g., Helodermatidae), and mammal (e.g., Marsupialia) groups, and the first North American appearance of other taxa such as tyrannosaurids, pachycephalosaurs, and snakes. Although the origin of many groups is unclear, combined biostratigraphic and phylogenetic evidence suggests an Old World, specifically Asian, origin for some of the taxa, an hypothesis that is consistent with existing evidence from tectonics and marine invertebrates. Large-bodied herbivores are mainly represented by low-level browsers, ornithopod dinosaurs, whose radiations have been hypothesized to be related to the initial diversification of angiosperm plants. Diversity at the largest body sizes (>10(6) g) is low, in contrast to both preceding and succeeding faunas; sauropods, which underwent demise in the Northern hemisphere coincident with the radiation of angiosperms, apparently went temporarily unreplaced by other megaherbivores. Morphologic and taxonomic diversity among small, omnivorous mammals, multituberculates, is also low. A later apparent increase in diversity occurred during the Campanian, coincident with the appearance of major fruit types among angiosperms, suggesting the possibility of adaptive response to new resources. 相似文献
69.
OH Suleiman BJ Conway P Quinn RG Antonsen FG Rueter RJ Slayton DC Spelic 《Canadian Metallurgical Quarterly》1997,203(2):471-476
PURPOSE: To determine the average abdominal entrance air kerma, low-contrast sensitivity, and spatial resolution in upper gastrointestinal tract fluoroscopy in the United States. MATERIALS AND METHODS: A random sample of fluoroscopic facilities was selected to be surveyed for the Nationwide Evaluation of X-ray Trends program. Measurements were performed by using a newly developed fluoroscopic phantom. The surveys were conducted by state radiation control personnel. RESULTS: Average air kerma rates 1 cm above the tabletop, free in air, were 43 mGy/min (n = 340). The rate increased to 64 mGy/min when a 1.6-mm-thick copper filter, which simulated the use of barium contrast medium, was added to increase attenuation. The average entrance air kerma, free in air, for radiographs was 3.4 mGy, and an average of 12 radiographs were obtained per examination. Of 352 facilities surveyed, 306 (87%) were able to resolve wire mesh with 20 or more lines per inch. Of 339 facilities for which percentage contrast could be calculated, 192 (57%) had minimum percentage contrast values of 4% or more. CONCLUSION: Spatial resolution for fluoroscopy is adequate for most of the facilities surveyed, but a substantial proportion of facilities could not visualize low-contrast test objects, which strongly suggests image quality problems. 相似文献
70.