全文获取类型
收费全文 | 258篇 |
免费 | 6篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 28篇 |
金属工艺 | 10篇 |
机械仪表 | 14篇 |
建筑科学 | 7篇 |
能源动力 | 9篇 |
轻工业 | 9篇 |
水利工程 | 4篇 |
无线电 | 19篇 |
一般工业技术 | 37篇 |
冶金工业 | 103篇 |
原子能技术 | 5篇 |
自动化技术 | 17篇 |
出版年
2021年 | 2篇 |
2019年 | 3篇 |
2017年 | 6篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 10篇 |
2012年 | 2篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1998年 | 19篇 |
1997年 | 19篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 15篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1978年 | 2篇 |
1977年 | 8篇 |
1976年 | 4篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1957年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有264条查询结果,搜索用时 10 毫秒
71.
R. F. Domagala D. W. Levinson D. J. McPherson 《JOM Journal of the Minerals, Metals and Materials Society》1957,9(10):1191-1196
Alloys containing 1.3, 3.3, 5.4, and 7.5 pct Mo were prepared using high purity molybdenum and sponge zirconium. Time-temperature-transformation curves were established for these alloys based on the resistivity vs time of anneal curves of isothermally quenched rods. Tensile and impact bars of each alloy were heat treated by isothermal quench techniques as well as by quench and reheat treatments. These bars were then machined, tested, and the properties compared. Optimum properties could be developed in the 1.3 pct Mo alloy using the isothermal quench technique. The 3.3, 5.4, and 7.5 pct Mo alloys exhibited a brittle behavior irrespective of type of heat treatment. An ω or transition phase in the β → α transformation was discovered which undoubtedly accounts for most of the brittleness observed. The ω phase has been tentatively indexed as tetragonal, c/a= 1.45. Mechanical properties of unalloyed sponge zirconium are presented for comparison. 相似文献
72.
73.
R. McPherson 《Journal of Materials Science》1973,8(6):859-862
The structure of Al2O3-Cr2O3 powders prepared by plasma oxidation of the mixed halides has been examined by X-ray diffraction, electron microscopy and
electron spin resonance. The powders consisted predominantly of faceted spherical particles of a well crystallized solid solution
of Cr2O3 in θ-Al2O3, with diameters of the order of 0.1 μm. Some larger particles of α-Cr2O3 were present in powders containing 17.8 and 24 wt% Cr2O3. The maximum solid solubility of Cr2O3 in θ-Al2O3 observed was 18 wt%. It is suggested that nucleation of crystallization of liquid Al2O3-Cr2O3 droplets occurs as a structure based on cubic close packing of oxygen ions and that the presence of chromium results in ordering
to the θ-Al2O3 form rather than the δ-Al2O3 form usually observed in alumina powders prepared by plasma methods. 相似文献
74.
Using 28 intact families, comparatively unstructured discussions between parents and their disturbed adolescent child concerning an important problem were assessed by means of a coding system designed to measure the intent of each communication made in the course of the interaction. Consistent differences were found between child behavior disturbance and parental verbal behavior when the families were divided into subgroups according to the adolescents' manifest style of problem expression. Findings support the view that there are consistent relationships between different patterns of familial behavior and the symptoms of the adolescent child. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
75.
In a prospective study of the value of gallium-67 scintigraphy in cases of multisystem malignant melanoma, 69 scans were obtained for 36 patients. No abnormality was found in 18 scans; in only 3 was there other evidence of disease. Of 54 sites of disease demonstrated by scintigraphy, 40 were correlated with other investigations: biopsy (5), surgery (7), autopsy (7), radiographic (13), or clinical (8). Metastatic melanoma was found in 37 (69%) of the sites; no such disease was found in 3 (5.7%). The life expectancy of patients with an abnormal scan was shorter than that of patients with a normal scan. Gallium studies reliably indicated the extent of multisystem melanoma, and are of value in clinical management. 相似文献
76.
The adult population of a small Victorian town was interviewed for current analgesic consumption and the replies were validated by urine testing. One thousand four hundred and fifty-six subjects were ranked by stated analgesic consumption, and the 50 highest consumers matched for age and sex with non-consumers. Early morning urine specimens were collected and no significant difference in osmolality or white cell excretion rates was found between the two groups. It was concluded that the absolute risk of renal impairment on chronic analgesic consumers is low, and that patients on therapeutic regimens, including analgesics, may be reassured that any risk is minimal. 相似文献
77.
78.
In a collaborative investigation in which 4 laboratories took part, the Rose Bengal Test (RBT), Serum Agglutination Test (SAT) and 4 different Complement Fixation (CFT) techniques were evaluated in selected cattle for the diagnosis of bovine brucellosis, by comparing the results they gave with the bacteriological examination of a selection of lymph nodes taken from the same animals at slaughter. The RBT correctly classified all but 1 of 79 culture-positive cattle, but was more often positive in culture-negative animals than the other tests. The RBT may be most useful as a screen test. 11% of the culture-positive cattle had SAT titres below 100 iu and almost 4% of them had less than 30 iu. However, the SAT was more effective in cattle vaccinated with the 45/20 vaccine. The CFT, in 1 of 4 techniques used, identified all of the culture-positive cattle at a serum dilution of 1/4 or above and was considered to be far superior to the SAT as a diagnostic test, except perhaps in cattle vaccinated with the 45/20 vaccine. 相似文献
79.
Haas L.M. Chang W. Lohman G.M. McPherson J. Wilms P.F. Lapis G. Lindsay B. Pirahesh H. Carey M.J. Shekita E. 《Knowledge and Data Engineering, IEEE Transactions on》1990,2(1):143-160
The purpose of the Starburst project is to improve the design of relational database management systems and enhance their performance, while building an extensible system to better support nontraditional applications and to serve as a testbed for future improvements in database technology. The design and implementation of the Starburst system to date are considered. Some key design decisions and how they affect the goal of improved structure and performance are examined. How well the goal of extensibility has been met is examined: what aspects of the system are extensible, how extensions can be done, and how easy it is to add extensions. Some actual extensions to the system, including the experiences of the first real customizers, are discussed 相似文献
80.
WW Hauck BS Bloom CK McPherson RJ Nickerson T Colton OL Peterson 《Canadian Metallurgical Quarterly》1976,236(16):1864-1871
In a national surgical manpower questionnaire survey, 76% of those MD and DO surgeons who were contactable returned questionnaires that included a log diary reporting details of their daily activities. Comparisons were made of allocation of professional time, number of operations performed, and net income of respondents by physician classification (including certification), specialty, practice arrangement, age, and census division. The mean professional workweek was estimated at 46 hours for all respondents. More than two thirds of the total professional time was spent in direct patient care; about half the surgeon's time was spent in the hospital, with nearly 20% in the operating room. The median annual work load of respondents was 170 operations. Their median annual net income was $45,700. 相似文献