全文获取类型
收费全文 | 1879篇 |
免费 | 0篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 4篇 |
金属工艺 | 1篇 |
机械仪表 | 6篇 |
建筑科学 | 1篇 |
轻工业 | 5篇 |
冶金工业 | 1854篇 |
原子能技术 | 1篇 |
自动化技术 | 5篇 |
出版年
2014年 | 1篇 |
2013年 | 1篇 |
2009年 | 2篇 |
2008年 | 1篇 |
2007年 | 7篇 |
2004年 | 2篇 |
2003年 | 8篇 |
1999年 | 54篇 |
1998年 | 632篇 |
1997年 | 314篇 |
1996年 | 213篇 |
1995年 | 102篇 |
1994年 | 112篇 |
1993年 | 110篇 |
1992年 | 13篇 |
1991年 | 17篇 |
1990年 | 24篇 |
1989年 | 27篇 |
1988年 | 25篇 |
1987年 | 19篇 |
1986年 | 15篇 |
1985年 | 13篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 18篇 |
1978年 | 2篇 |
1977年 | 38篇 |
1976年 | 85篇 |
1959年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有1879条查询结果,搜索用时 0 毫秒
101.
102.
JK Jain 《Canadian Metallurgical Quarterly》1985,32(8):5456-5458
103.
Relaxin, a peptide hormone responsible for the widening of the birth canal in mammals, has been purified from the ovaries of pregnant hogs. The amino acid sequences of its constituent A and B chains were determined, and the positions of the disulfide cross-links were established. Relaxin was shown to be identical to insulin with respect to its disulfide bond distribution, but significant homology was lacking in other positions. These findings suggest that relaxin and insulin were derived from a common ancestral gene. Since the intrauterine mode of propagation is synonymous with the development of mammals, the genetic distance between insulin and relaxin should therefore permit an estimate of the earliest possible time of commitment of one evolutionary branch to the development of mammals. This event was estimated to have occurred about 5 X 10(8) years ago. 相似文献
104.
The level of PGE is increased 10-fold in intestinal tissues during primary infection of the rat with Nippostrongylus brasiliensis. Peak levels (ca. 7,000 pg/cm) were assayed in the jejunal site of infection on day 7 of infection and similar levels were recorded in 'post-infection' (ileal) segments at this time. The level of PGE in 'post-infection' segments showed further increase to 12,000 pg/cm on day 10. The level of PGE also increased in 'pre-infection' (duodenal) but this was delayed by 4-5 days. The level of PGF also increased during primary infection (from about 100 to 950 pg/cm) but this occurred after expulsion. Increase in the level of PGE occurred earlier (at 3-4 days) during secondary challenge given 19 days after primary infection, but the PGE levels followed the primary response when challenge was given 10 weeks after primary infection. It is suggested that PGE plays a dual role in parasite immunity. (1) PGE may directly affect metabolism of the parasite. In this event it is also suggested that protective antibodies cause the release of PG. (2) Elevated levels of PGE act indirectly by affecting gastrointestinal function which alters the microenvironment at the site of infection. The duodenal migration of parasites may be due to this effect of PGE. 相似文献
105.
106.
107.
108.
A clinical study of hand strength and complications in 41 patients with a transmetacarpal amputation of the index finger found that the average prehension strength was reduced by 20% and stability of grip by almost 50%. Tendon transfers or other operative modifications did not affect the results. The most disabling complication, hyperesthesia, or painful sensitivity to light touch, in the thumb--long-finger web was present in 59% of patients and interfered with hand function in 37%. 相似文献
109.
110.
VK Naik AN Thakur AR Sheth UM Joshi SS Rao DS Pardanani JK Kulsreshtha RK Handa 《Canadian Metallurgical Quarterly》1976,48(2):441-442
The testosterone concentration in allantoic fluid between 90 and 150 days of gestation in cattle can be used to determine the fetal sex; values were 442 +/- 20-3 (S.E.M.) pg testosterone/ml for males fetuses and 215 +/- 8-2 pg/ml for female fetuses. 相似文献