全文获取类型
收费全文 | 8662篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
综合类 | 5篇 |
化学工业 | 74篇 |
金属工艺 | 7篇 |
机械仪表 | 1篇 |
建筑科学 | 9篇 |
能源动力 | 1篇 |
轻工业 | 17篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
武器工业 | 1篇 |
无线电 | 12篇 |
一般工业技术 | 65篇 |
冶金工业 | 8437篇 |
原子能技术 | 3篇 |
自动化技术 | 25篇 |
出版年
2020年 | 8篇 |
2019年 | 2篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2012年 | 6篇 |
2011年 | 10篇 |
2010年 | 9篇 |
2009年 | 14篇 |
2008年 | 10篇 |
2007年 | 18篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 15篇 |
2003年 | 16篇 |
2002年 | 4篇 |
2001年 | 7篇 |
2000年 | 12篇 |
1999年 | 282篇 |
1998年 | 2695篇 |
1997年 | 1491篇 |
1996年 | 959篇 |
1995年 | 551篇 |
1994年 | 422篇 |
1993年 | 533篇 |
1992年 | 63篇 |
1991年 | 106篇 |
1990年 | 102篇 |
1989年 | 90篇 |
1988年 | 97篇 |
1987年 | 95篇 |
1986年 | 100篇 |
1985年 | 69篇 |
1984年 | 2篇 |
1983年 | 10篇 |
1982年 | 37篇 |
1981年 | 41篇 |
1980年 | 78篇 |
1979年 | 6篇 |
1978年 | 13篇 |
1977年 | 181篇 |
1976年 | 437篇 |
1975年 | 9篇 |
1972年 | 2篇 |
1967年 | 1篇 |
1963年 | 2篇 |
1955年 | 7篇 |
1954年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有8664条查询结果,搜索用时 10 毫秒
121.
We reviewed the use of a low radiation portable fluoroscopy unit in 100 patients. The most common indication was closed reduction of distal radial fractures. Fracture and joint stability were assessed on the real-time monitor and stored on videotape. Static images were stored on thermographic paper. Fluoroscopically guided joint injections and localization of implants, foreign bodies and bone tumours were performed. Fluoroscopy is a useful adjunct to arthroscopic assisted fracture reduction and other arthroscopic procedures such as distal ulnar resection. These new generation units produce superior resolution images, are easy to manoeuvre and do not require a radiographer. 相似文献
122.
123.
124.
I Scott J O'Shea M Bunce JM Tiercy JR Argüello H Firman J Goldman HG Prentice AM Little JA Madrigal 《Canadian Metallurgical Quarterly》1998,92(12):4864-4871
In comparison with HLA-matched sibling bone marrow transplants, unrelated donor transplants are associated with increased graft-versus-host disease and graft failure. This is likely in part due to HLA incompatibilities not identified by current matching strategies. High resolution DNA-based typing methods for HLA class II loci have improved donor selection and treatment outcome in unrelated donor bone marrow transplantation. By using DNA-based typing methods for HLA-A and -B on a cohort of 100 potential bone marrow donor/patient pairs, we find that serological typing for HLA class I is limited in its ability to identify incompatibilities in unrelated pairs. Furthermore, the incompatibilities identified are associated with the presence at high frequency of alloreactive cytotoxic T-lymphocyte precursors. DNA typing also indicates that HLA-C mismatches are common in HLA-A and -B serologically matched pairs. Such mismatches appear to be significantly less immunogenic with respect to cytotoxic T-lymphocyte recognition, but are expected to influence natural killer cell activity. Thus, improved resolution of HLA class I shows many previously undisclosed mismatches that appear to be immunologically functional. Use of high resolution typing methods in routine matching is expected to improve unrelated donor selection and transplant outcome. 相似文献
125.
126.
P Wesseling JA van der Laak M Link HL Teepen DJ Ruiter 《Canadian Metallurgical Quarterly》1998,29(4):352-358
BACKGROUND: Despite concerns about its prevalence and ramifications, harassment has not been well quantified among physicians. Previous published studies have been small, have surveyed only 1 site or a convenience sample, and have suffered from selection bias. METHODS: Our database is the Women Physicians' Health Study, a large (4501 respondents; response rate, 59%), nationally distributed questionnaire study. We analyzed responses concerning gender-based and sexual harassment. RESULTS: Overall, 47.7% of women physicians reported ever experiencing gender-based harassment, and 36.9% reported sexual harassment. Harassment was more common while in medical school (31% of gender-based and 20% for sexual harassment) or during internship, residency, or fellowship (29% for gender-based and 19% for sexual harassment) than in practice (25% for gender-based and 11% for sexual harassment). Respondents more likely to report gender-based harassment were physicians who were now divorced or separated and those specializing in historically male specialties, whereas those of Asian and other (nonwhite, nonblack, non-Asian, non-Hispanic) ethnicity, those living in the East, and those self-characterized as politically very conservative were less likely to report gender-based harassment. Being younger, born in the United States, or divorced or separated were correlated with reporting ever experiencing sexual harassment; those who were Asian or who were currently working in group or government settings were less likely to report it. Those who felt in control of their work environments, were satisfied with their careers, and would choose again to become physicians reported lower prevalences of ever experiencing harassment. Those with histories of depression or suicide attempts were more likely to report ever having been harassed. CONCLUSIONS: Women physicians commonly perceive that they have been harassed. Experiences of and sensitivity to harassment differ among individuals, and there may be substantial professional and personal consequences of harassment. Since reported rates of sexual harassment are higher among younger physicians, the situation may not be improving. 相似文献
127.
128.
129.
P Ussetti J Urbina C Pantoja J Sidne JA Martínez MA Martínez I Sánchez J Cobos O Rojas 《Canadian Metallurgical Quarterly》1996,14(2):80-85
BACKGROUND: Tuberculin reactivity varies on the basis of the PPD lot and the population studied. AIMS: To compare tuberculin reactivity in the elderly following successive applications of PPD from 2 different lots. POPULATION: Elderly nursing-home residents, from the province of Guadalajara, Spain. METHODS: The elderly were randomly selected and administered with a first Mantoux intradermoreaction of 2 UT of PPD-RT23 or 2 UT of PPD-CT68. The study was performed in a scaled basis, eliminating the reactors (transversal induration > or = 5 mm at 72 h). The non reactors were restudied with a second and third test in alternative arms at a 7-day interval with the same lot and initial dosis of PPD. At one year the scaled study was repeated with 2 UT of PPD-CT68. RESULTS: Eight hundred and thirty elderly persons (79 +/- 9 years) were studied, with 410 receiving PPD-RT23 and 420 receiving PPD-CT68. No differences were observed in the percentage of initial reactors (31% vs 29%; p = 0.26) or in the booster reactors (23% vs 20%; p = 0.16). The PPD-RT23 was found to trigger more intensive reactions than the PPD-CT68 leading to a greater frequency of indurations > 14 mm. After one year, the percentage of stable reactions was similar in both groups (50.5% vs 49.5%; NS). CONCLUSIONS: 1) In elderly nursing-home residents 2 UT of PPD-RT23 and 2 UT of PPD-CT68 showed similar results in regard to the number of reactors and the frequency of booster reactions. 2) The proportion of intense reactions was greater with 2 UT of PPD-RT23 than with 2 UT of PPD-CT68. 3) The stability of the reactions at one year was independent of the lot used in the first phase. 相似文献
130.