全文获取类型
收费全文 | 2214篇 |
免费 | 0篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 35篇 |
金属工艺 | 7篇 |
机械仪表 | 6篇 |
建筑科学 | 5篇 |
能源动力 | 2篇 |
轻工业 | 17篇 |
水利工程 | 2篇 |
无线电 | 30篇 |
一般工业技术 | 16篇 |
冶金工业 | 2073篇 |
原子能技术 | 1篇 |
自动化技术 | 18篇 |
出版年
2020年 | 3篇 |
2013年 | 3篇 |
2011年 | 4篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 9篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 75篇 |
1998年 | 623篇 |
1997年 | 324篇 |
1996年 | 201篇 |
1995年 | 106篇 |
1994年 | 128篇 |
1993年 | 121篇 |
1992年 | 11篇 |
1991年 | 22篇 |
1990年 | 24篇 |
1989年 | 38篇 |
1988年 | 34篇 |
1987年 | 31篇 |
1986年 | 32篇 |
1985年 | 30篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 12篇 |
1981年 | 23篇 |
1980年 | 23篇 |
1979年 | 7篇 |
1978年 | 11篇 |
1977年 | 71篇 |
1976年 | 172篇 |
1975年 | 4篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1957年 | 1篇 |
1956年 | 3篇 |
1955年 | 2篇 |
1954年 | 2篇 |
排序方式: 共有2214条查询结果,搜索用时 15 毫秒
101.
RB D'Agostino 《Canadian Metallurgical Quarterly》1998,4(2):109-111; discussion 111-3
102.
103.
WF Gee HL Holtgrewe PC Albertsen MS Litwin MJ Manyak MP O'Leary MR Painter RT Blizzard RB Fenninger L Emmons 《Canadian Metallurgical Quarterly》1996,156(5):1778-1780
PURPOSE: Trends of urologist practice patterns in evaluating and treating impotence, incontinence and infertility in the United States were assessed. MATERIALS AND METHODS: In July 1995 the executive interviewing branch of the Gallup Organization selected randomly and interviewed by telephone 533 practicing urologists in the United States who had provided urological patient care for more than 20 hours per week, practiced in 1994 and completed a urological residency program. RESULTS: Treatment of male sexual dysfunction and female urinary incontinence comprises a significant portion of the professional activity of United States urologists. However, evaluation and management of male infertility occupy a small portion of the average urological work load. While more than half of United States urologist office clinical laboratories were inspected in 1994, only 2% failed evaluation due to major deficiencies. CONCLUSIONS: Male sexual dysfunction and female urinary incontinence are major areas of urological practice in the United States but male infertility is not. Few United States urologist clinical laboratories failed inspection because of major deficiencies. 相似文献
104.
105.
106.
107.
108.
MM Miller HP Bennett RB Billiar KB Franklin D Joshi 《Canadian Metallurgical Quarterly》1998,33(7-8):729-757
Our studies in the C57BL/6J mouse have been designed to examine the interactions of aging and the ovary, and their mutual effects on neuroendocrine function. In the pituitary, ovarian status and not age determines responsiveness to gonadotropin hormone releasing hormone (GnRH), but estrogen (E2) is an important mediator in CNS changes, and removal of the ovary (OVX) is deleterious to the neuroendocrine hypothalamus. OVX for just six days in young animals results in synaptic loss between noradrenergic terminals and gonadotropin hormone releasing hormone (GnRH) neurons. Long-term OVX, hypothesized to protect against neuroendocrine aging, fails to guard against any studied age-related changes. Some age-related changes occur as early as midlife. Although neuron number remains constant at middle age, opiatergic neurons undergo significant functional changes by producing opiate antagonist peptides. This change appears to be caused by alterations in the prohormone convertases, which cleave propeptide to peptide. Altered peptides may trigger the loss of reproductive capacity. The midlife shift in opiate peptide production is a component of natural developmental processes that begin in the neonate and continue through old age. In the cholinergic system, E2 mediates numbers of cholinergic receptors, cholinergic neurons, and cholinergic-modulated memory systems in both young and old animals. Regardless of age, ovarian steroids, if present at physiologic levels, are beneficial to the neuroendocrine CNS, and long-term deprivation from ovarian-produced factors is deleterious in the systems we have examined. Our studies have shown that deprivation from ovarian steroid hormones in the female appears to be a major factor in the health of the CNS and in events associated with aging. 相似文献
109.
110.