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111.
The activity of alkaline phosphatase (AP) was studied in adults of highly active (HA) and low active (LA) Drosophila melanogaster strains and their F1 hybrids, both under normal conditions and after a heat shock (38 degrees C). Under normal conditions, the HA strain expressed a higher AP activity compared to that in the wild-type strain Canton-S and dominated in respect to this character. The AP activity showed a sexual dimorphism, as it was higher in females of both strains. Heat shock (38 degrees C) induced no alterations in the AP activity of D. melanogaster. 相似文献
112.
BR Babu SJ Zhu AV Ramayya JH Hamilton LK Peker MG Wang TN Ginter J Kormicki WC Ma JD Cole R Aryaeinejad K Butler-Moore YX Dardenne MW Drigert GM Ter-Akopian YT Oganessian JO Rasmussen S Asztalos IY Lee AO Macchiavelli SY Chu KE Gregorich MF Mohar S Prussin MA Stoyer RW Lougheed KJ Moody JF Wild 《Canadian Metallurgical Quarterly》1996,54(2):568-571
113.
Recombinant papillomavirus-like particles have recently been shown to be highly effective for the prevention of papillomavirus infections and associated tumors, and a virus-like particle-based vaccine against the most prevalent HPV causing genital infection in humans will be developed in the near future. Another use of these virus-like particles may lie in gene therapy and DNA immunization. We report here that human papillomavirus-like particles composed of the major capsid protein (L1) of HPV-16 are able to package unrelated plasmid DNA in vitro and then to deliver this foreign DNA to eukaryotic cells with the subsequent expression of the encoded gene. The results indicate higher gene transfer than with DNA alone or with liposome. Virus-like particles are a very promising vehicle for delivering genetic material into target cells. Moreover, the preparation of the gene transfer vehicle is relatively easy. 相似文献
114.
Estrogen replacement therapy and worsening of radiographic knee osteoarthritis: the Framingham Study
Y Zhang TE McAlindon MT Hannan CE Chaisson R Klein PW Wilson DT Felson 《Canadian Metallurgical Quarterly》1998,41(10):1867-1873
OBJECTIVE: To examine whether estrogen replacement therapy (ERT) prevents worsening of radiographic knee osteoarthritis (OA) in elderly women. METHODS: A total of 551 women ages 63-91 years (mean age 71) in the Framingham Study were followed up from biennial examination 18 (1983-1985) to examination 22 (1992-1993). Data on postmenopausal ERT were obtained every 2 years. Subjects were classified into 3 groups according to their estrogen use at biennial examination 18: never users (n = 349), past users (n = 162), and current users (n = 40). Women received anteroposterior weight-bearing knee radiographs at examinations 18 and 22. Using the Kellgren and Lawrence criteria, global radiographic knee OA was assessed, (grade range 0-4) and individual radiographic features, such as osteophytes and joint space narrowing, were scored from 0 to 3. Worsening was defined as either development of radiographic OA that was not present at baseline (incident OA) or progression of baseline radiographic OA by > or =1 Kellgren and Lawrence grade (progressive OA). Potential confounding factors included age, body mass index, weight change, smoking, knee injury, physical activity level, and bone mineral density at the femoral neck. RESULTS: During 8 years of followup, 17.4% of knee radiographic scores worsened by 1 grade and 5.8% by 2 or 3 grades among never users of ERT. Among current estrogen users, only 11.7% of knee radiographic scores worsened by 1 grade and none worsened by more than 1 grade. After adjusting for age and other potential confounding factors, the relative risk of incident radiographic knee OA in comparison with never users of estrogen was 0.8 (95% confidence interval [95% CI] 0.5-1.4) in past users and 0.4 (95% CI 0.1-3.0) in current users. Current use of estrogen also showed a trend toward decreased risk of progressive knee OA compared with never use (odds ratio [OR] 0.5, 95% CI 0.1-2.9). When both incident and progressive radiographic knee OA cases were combined, current ERT use had a 60% decreased risk compared with never use (OR 0.4, 95% CI 0.1-1.5). CONCLUSION: This is the first prospective cohort study to examine the effects of ERT on radiographic knee OA. The results indicate that current use of ERT had a moderate, but not statistically significant, protective effect against worsening of radiographic knee OA among elderly white women. These findings corroborate those of cross-sectional studies and point further to a potential benefit of female hormones in OA. 相似文献
115.
116.
The strain rate sensitivity of flow stress has long been recognized as an important factor in determining superplastic ductility,
and its relationship to high tensile elongations is well understood from the mechanics point of view. However, the measurements
of this parameter and other properties of superplastic materials are challenging, and quite varied results are observed from
different test procedures used. In this paper a discussion of the various characterization methods is presented, and the relationship
between the superplastic characteristics and the microstructure is brought forth. The applicability of the uniaxial superplastic
properties on the biaxial deformation behavior as in the superplastic forming process is addressed, including a relationship
of such properties to the selection of forming parameters.
This paper is based on a presentation made at the symposium “On the Mechanical, Microstructural and Fracture Processes in
Superplasticity” held at the annual meeting of the AIME in Pittsburgh, PA on October 7, 1980 under the sponsorship of the
Flow and Fracture Activity of the Materials Science Division of ASM. 相似文献
117.
Scott Hamilton 《Information & Management》1982,5(6):339-347
Different strategies for conducting empirical research in the Management Information Systems (MIS) field are discussed. Strategies employed in 532 MIS articles published in 15 journals during the 1970–1979 time period are analyzed. The trends are analyzed over the ten year period with respect to the differences between articles authored by practitioners and academic, differences between articles that are cited frequently versus infrequently, and the relationship with the type of research conducted.The analysis points out that more than two thirds of published MIS research by either academicians or practitioners had utilized non-empirical approaches and focused on a single variable. Case studies are the most commonly employed empirical strategy and most studies do not measure the impact of independent variables on the process of using developing, or operating information systems. The analysis suggests that MIS journal articles employing empirical research strategies are cited more frequently than nonempirical ones. 相似文献
118.
M. W. Mahoney C. H. Hamilton A. K. Ghosh 《Metallurgical and Materials Transactions A》1983,14(8):1593-1598
Forming limits in conventional sheet metal forming are given by strain levels obtainable prior to the onset of a localized neck or tear in the sheet. While the external appearance of such a neck is not observed in superplastic metals until strains become quite large, the formation of internal cavities could dictate the tolerable levels of strain in formed components. In this paper, these useful strain limits for a superplastic 7475 Al alloy have been explored. The approach used was to establish the influence of strain state (uniaxial, plane strain, and balanced biaxial) on the inception and growth characteristics of cavities and to correlate the extent of cavitation with material properties. Based on these data, it was then possible to establish strain states for which little or no loss in properties was observed, and thereby to define forming limits for superplastic forming this material. These results, coupled with comparisons against strains developed in actual parts as well as analytically predicted strains, show that a wide range of structural parts can be superplastically formed within the constraints of the recommended forming limits. 相似文献
119.
120.
Organochlorine insecticide residues in wild birds in Britain 总被引:1,自引:0,他引:1
C H Walker G A Hamilton R B Harrison 《Journal of the science of food and agriculture》1967,18(3):123-129
Organochlorine insecticide residues in a wide range of wild birds and their eggs from all over Britain have been determined by gas-liquid chromatography and paper chromatography. Higher residues were found in predatory species than in omnivorous or herbivorous species. To illustrate the residue pattern in predatory species analytical data for specimens of the Heron, Kestrel and Sparrow-Hawk have been summarised. The source of the residues and their possible effects upon birds are discussed. 相似文献