全文获取类型
收费全文 | 15200篇 |
免费 | 1797篇 |
国内免费 | 1篇 |
出版年
2021年 | 139篇 |
2018年 | 156篇 |
2017年 | 127篇 |
2016年 | 272篇 |
2015年 | 363篇 |
2014年 | 414篇 |
2013年 | 535篇 |
2012年 | 651篇 |
2011年 | 631篇 |
2010年 | 487篇 |
2009年 | 463篇 |
2008年 | 622篇 |
2007年 | 652篇 |
2006年 | 542篇 |
2005年 | 567篇 |
2004年 | 547篇 |
2003年 | 545篇 |
2002年 | 465篇 |
2001年 | 425篇 |
2000年 | 431篇 |
1999年 | 375篇 |
1998年 | 170篇 |
1997年 | 179篇 |
1996年 | 159篇 |
1995年 | 147篇 |
1994年 | 177篇 |
1993年 | 142篇 |
1992年 | 351篇 |
1991年 | 340篇 |
1990年 | 341篇 |
1989年 | 295篇 |
1988年 | 296篇 |
1987年 | 268篇 |
1986年 | 251篇 |
1985年 | 271篇 |
1984年 | 258篇 |
1983年 | 261篇 |
1982年 | 207篇 |
1981年 | 152篇 |
1980年 | 167篇 |
1979年 | 228篇 |
1978年 | 201篇 |
1977年 | 183篇 |
1976年 | 174篇 |
1975年 | 173篇 |
1974年 | 182篇 |
1973年 | 177篇 |
1972年 | 160篇 |
1971年 | 143篇 |
1970年 | 128篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
1.
2.
3.
Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect. 相似文献
4.
5.
6.
7.
8.
Administration of high-dose Antide to ovariectomized monkeys results in rapid, prolonged, and reversible inhibition of gonadotropin secretion. The present study examined whether similar long-term control would be manifested in the menstrual cycle of intact primates. Antide administration at a dose of either 3.0 or 18.0 mg/kg induced rapid suppression of bioassayable LH concentrations, precipitating a concurrent fall in serum progesterone concentrations from 7.9 +/- 3.6 and 5.8 +/- 1.0 ng/ml (mean +/- SEM) on the day of injection to 0.6 +/- 0.2 and 0.5 +/- 0.1 ng/ml by 2 days post-treatment, respectively. This Antide-induced luteolysis was accompanied by the premature onset of menses within 3 days. The next menses following Antide administration was delayed. Ultimately, folliculogenesis culminating in normal follicular-phase estradiol production, ovulation, and subsequent normal luteal-phase progesterone production did occur in all treated monkeys. Menses resumed 54 +/- 9 and 75 +/- 13 days after treatment with 3.0 and 18.0 mg/kg Antide, respectively. No allergic cutaneous or peripheral reactions were seen, even at the highest dose of Antide. Thus, the long duration of action of high-dose Antide reported earlier in ovariectomized monkeys is also demonstrated in intact primates. These findings, along with the apparent absence of histamine-release effects even at high doses, suggest that Antide is a GnRH antagonist deserving clinical evaluation. 相似文献
9.
10.
DETECTION OF FRNA COLIPHAGES IN GROUNDWATER 总被引:1,自引:0,他引:1
A.H. Havelaar M.D. Sobsey F.P. Williams Jr R.E. Stetler 《Letters in applied microbiology》1995,20(6):396-397