全文获取类型
收费全文 | 7004篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 68篇 |
金属工艺 | 4篇 |
机械仪表 | 3篇 |
建筑科学 | 5篇 |
矿业工程 | 5篇 |
能源动力 | 6篇 |
轻工业 | 16篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 20篇 |
一般工业技术 | 51篇 |
冶金工业 | 6786篇 |
原子能技术 | 2篇 |
自动化技术 | 41篇 |
出版年
2022年 | 3篇 |
2020年 | 4篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 12篇 |
2012年 | 11篇 |
2011年 | 12篇 |
2010年 | 12篇 |
2009年 | 9篇 |
2008年 | 9篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 10篇 |
2004年 | 10篇 |
2003年 | 13篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 10篇 |
1999年 | 213篇 |
1998年 | 2333篇 |
1997年 | 1295篇 |
1996年 | 822篇 |
1995年 | 429篇 |
1994年 | 345篇 |
1993年 | 420篇 |
1992年 | 39篇 |
1991年 | 47篇 |
1990年 | 54篇 |
1989年 | 49篇 |
1988年 | 55篇 |
1987年 | 58篇 |
1986年 | 55篇 |
1985年 | 37篇 |
1984年 | 2篇 |
1983年 | 18篇 |
1982年 | 25篇 |
1981年 | 30篇 |
1980年 | 64篇 |
1979年 | 4篇 |
1978年 | 13篇 |
1977年 | 138篇 |
1976年 | 281篇 |
1975年 | 12篇 |
1972年 | 2篇 |
1970年 | 3篇 |
1966年 | 1篇 |
1955年 | 3篇 |
排序方式: 共有7012条查询结果,搜索用时 0 毫秒
41.
42.
MJ Reed 《Canadian Metallurgical Quarterly》1976,26(5):762-770
In a longitudinal study on 13 adult female stumptailed macaques, Macaca speciosa, peripheral blood samples were analyzed hematologically and the in vitro response of the lymphocytes to the common mitogens concanavalin A, phytohemagglutinin and pokeweed mitogen were investigated. The results showed that the total leukocyte and differential counts in each animal remained quite stable throughout the 3-month experiment. The responses in culture to the mitogens showed that there were differences in the stimulation obtained by each mitogen and that the animals may be placed into high, medium and low groups based on differences in their level of response. 相似文献
43.
CL Gugliucci MJ O''Sullivan W opperman M Gordon ML Stone 《Canadian Metallurgical Quarterly》1976,125(4):435-441
Over the last 2 years at Metropolitan Hospital Medical Center 245 diabetic women have been seen on the obstetric service. This complication of pregnancy comprises 7.9 per cent of 3,076 deliveries, resulting in an over-all uncorrected perinatal mortality rate of 2.9 per cent. We believe that early detection and strict rigid control of diabetes is the key to improved perinatal outcome. This article presents the classification, diagnosis, and management which have led to these results. 相似文献
44.
Two-year disease-free survival is considered highly predictive of therapeutic success with neuroblastoma and death from neuroblastoma greater than 5 years after diagnosis is a rare event. We report of an unusual case of death from neuroblastoma 20 years after diagnosis; a literature review and discussion of this rare phenomenon of late recurrence is also included. Five additional cases of late recurrence, defined as greater than 5 years after diagnosis, were found in the literature with adequate detail to be reviewed. Advanced disease was present at diagnosis in five of six cases; three of six had disseminated disease. No age or sex differences were noted. A peculiar tencency for recurrence during the teenage years, preceded by a long disease-free interval, was also present in all cases, perhaps a reflection of maturational alterations in the immune system or hormonal changes that previously had suppressed extensive disease. This phenomenon of late recurrence in neuroblastoma, albeit rare, adds another facet to the clinical behavior of an enigmatic and therapeutically unyielding childhood tumor. 相似文献
45.
During the incubation of arachidonic acid with platelet-rich plasma, a persistent activity appeared that caused the release of [14C]5-hydroxytryptamine from indomethacin-treated platelets. By the time-course of its appearance and disappearance, this release-inducing activity could be dissociated from prostaglandin endoperoxides and associated with thromboxane A2-like material. This material persists in plasma because of its continued production and increased stability. 相似文献
46.
47.
A simple progressive exercise test was performed before and after operation on five subjects undergoing mitral valve replacement and on five subjects undergoing aortic valve replacement. The responses of heart rate and ventilation were related to work rate )kilopond metres/min). The patients were also assessed clinically by the New York Heart Association grading and radiologically before each exercise test. The clinical grading was shown to be a poor guide to observed exercise tolerance, as the improvement noted in symptoms was not matched by the objective measurement of working capacity. Only two patients had normal exercise tolerance after surgery, although six of the ten patients claimed that they had no exertional dyspnoea after operation. The changes in simple ventilatory function tests before and after operation were generally small. We suggest that measurements of exercise tolerance before and after operation should be an essential part of heart valve replacement surgery. 相似文献
48.
JM Nelems JD Cooper RD Henderson T Peng MJ Phillips 《Canadian Metallurgical Quarterly》1976,22(3):260-264
Twenty-eight patients underwent open lung biopsy on an emergency basis. The clinical course in each case was deteriorating rapidly, and all were in respiratory failure. The correct diagnosis was established in 96% of the biopsies (27 of the 28 patients). The clinical diagnosis prior to biopsy was in error or incomplete in 15 (55%) of the patients. Specific therapy was lifesaving in 12 of the 28 patients. The value of the procedure outweighed the complications. Thrombocytopenia and positive end-expiratory pressure ventilation were not contraindications to biopsy. 相似文献
49.
A retrospective record analysis of 112 juvenile-onset diabetics with nephropathy was conducted in order to determine their clinical course. The mean duration of diabetes at the onset of proteinuria was 17.3+/-6.0 years. Early renal failure appeared two years after the onset of protein-uria, and severe renal failure (mean serum creatinine level, 8.5+/-3.9 mg/100 ml) four years after the onset of proteinuria. The mean duration of life after the onset of severe renal failure was six months. The mortality was 53%, with 59% of the deaths attributable to renal failure and 36% to cardiovascular disease. All patients experienced progressive deterioration of renal function as well as the other complications of diabetes, the rate of progression being accelerated toward the end of the course. Juvenile onset diabetics should be considered for renal transplantation before the serum creatinine level reaches 8.5 mg/100 ml. 相似文献
50.
JA Palmore MJ Furlong FX Buchmeier IH Park LM Souder 《Canadian Metallurgical Quarterly》1976,7(12):349-356
The characteristics of Korean family planning opinion leaders are assessed through a secondary analysis of the 1971 national survey conducted by the Korean Institute for Research in the Behavioral Sciences. In effect, what characterized Korean family planning opinion leaders was a rather national and democratic model. Those who had tried methods, discussed them, and knew a lot about them assumed leadership roles more than others. Place of residence, education, and other such variables mattered relatively little unless a woman had credibility imparted by actual use and knowledge imparted by use or discussions with family planning professionals. 相似文献