全文获取类型
收费全文 | 679182篇 |
免费 | 83123篇 |
国内免费 | 443篇 |
出版年
2016年 | 7627篇 |
2015年 | 11389篇 |
2014年 | 12997篇 |
2013年 | 18390篇 |
2012年 | 20906篇 |
2011年 | 21056篇 |
2010年 | 14072篇 |
2009年 | 13116篇 |
2008年 | 18599篇 |
2007年 | 19271篇 |
2006年 | 17734篇 |
2005年 | 17492篇 |
2004年 | 17096篇 |
2003年 | 16710篇 |
2002年 | 15979篇 |
2001年 | 29233篇 |
2000年 | 29527篇 |
1999年 | 23834篇 |
1998年 | 8937篇 |
1997年 | 9365篇 |
1996年 | 9077篇 |
1995年 | 8291篇 |
1994年 | 8380篇 |
1993年 | 8243篇 |
1992年 | 19731篇 |
1991年 | 18906篇 |
1990年 | 18414篇 |
1989年 | 18215篇 |
1988年 | 16631篇 |
1987年 | 16333篇 |
1986年 | 15054篇 |
1985年 | 14953篇 |
1984年 | 12639篇 |
1983年 | 11166篇 |
1982年 | 8829篇 |
1981年 | 8229篇 |
1980年 | 7563篇 |
1979年 | 12411篇 |
1978年 | 9675篇 |
1977年 | 9088篇 |
1976年 | 8589篇 |
1975年 | 9222篇 |
1974年 | 9930篇 |
1973年 | 9799篇 |
1972年 | 8943篇 |
1971年 | 8223篇 |
1970年 | 7054篇 |
1969年 | 6937篇 |
1968年 | 6163篇 |
1967年 | 5462篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
973.
974.
Effects of opioid blockade with nalmefene in older impotent men 总被引:2,自引:0,他引:2
We evaluated the effect of the opioid antagonist nalmefene on the HPG axis and on food consumption in 14 older impotent men. These patients had low to low normal mean serum testosterone values and normal gonadotrophin levels on screening evaluation. Normal response to GnRH was demonstrated in all the men. The protocol called for 24 hours of evaluation before and during administration of nalmefene 2.0 mg IV every 8 hours for 3 doses. During each 24 hour period, the following determinations were made: serum testosterone, FSH, and LH by five separate determinations between 8 AM and noon; 8 AM and 11 PM serum cortisols; 24 hour urine collections for free cortisol; and nocturnal penile tumescence (NPT). Food consumption was measured from 4 PM to 10 AM during the two periods. Nalmefene resulted in significant rises in testosterone, LH, and FSH. Nalmefene significantly elevated morning and evening cortisol measurements in all the patients. Nalmefene decreased total calorie consumption, principally by decreasing fat consumption. There was no effect on NPT. We conclude that in older impotent men, nalmefene acutely increases activity of the HPG axis and decreases calorie intake predominantly by decreasing fat consumption. 相似文献
975.
976.
977.
978.
W. H. Inman 《BMJ (Clinical research ed.)》1994,309(6954):608-609
979.
980.
The active moieties of the anti-biofilm natural compounds zosteric (ZA) and salicylic (SA) acids have been covalently immobilized on a low density polyethylene (LDPE) surface. The grafting procedure provided new non-toxic eco-friendly materials (LDPE-CA and LDPE-SA) with anti-biofilm properties superior to the conventional biocide-based approaches and with features suitable for applications in challenging fields where the use of antimicrobial agents is limited. Microbiological investigation proved that LDPE-CA and LDPE-SA: (1) reduced Escherichia coli biofilm biomass by up to 61% with a mechanism that did not affect bacterial viability; (2) significantly affected biofilm morphology, decreasing biofilm thickness, roughness, substratum coverage, cell and matrix polysaccharide bio-volumes by >80% and increasing the surface to bio-volume ratio; (3) made the biofilm more susceptible to ampicillin and ethanol. Since no molecules were leached from the surface, they remained constantly effective and below the lethal level; therefore, the risk of inducing resistance was minimized. 相似文献