全文获取类型
收费全文 | 1962篇 |
免费 | 115篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 41篇 |
儿科学 | 122篇 |
妇产科学 | 48篇 |
基础医学 | 243篇 |
口腔科学 | 32篇 |
临床医学 | 172篇 |
内科学 | 300篇 |
皮肤病学 | 27篇 |
神经病学 | 265篇 |
特种医学 | 173篇 |
外科学 | 276篇 |
综合类 | 23篇 |
预防医学 | 78篇 |
眼科学 | 6篇 |
药学 | 68篇 |
1篇 | |
肿瘤学 | 204篇 |
出版年
2021年 | 18篇 |
2020年 | 10篇 |
2019年 | 18篇 |
2018年 | 20篇 |
2017年 | 25篇 |
2016年 | 20篇 |
2015年 | 48篇 |
2014年 | 52篇 |
2013年 | 58篇 |
2012年 | 82篇 |
2011年 | 86篇 |
2010年 | 75篇 |
2009年 | 50篇 |
2008年 | 82篇 |
2007年 | 76篇 |
2006年 | 73篇 |
2005年 | 84篇 |
2004年 | 58篇 |
2003年 | 61篇 |
2002年 | 58篇 |
2001年 | 66篇 |
2000年 | 67篇 |
1999年 | 59篇 |
1998年 | 40篇 |
1997年 | 32篇 |
1996年 | 40篇 |
1995年 | 24篇 |
1994年 | 33篇 |
1993年 | 24篇 |
1992年 | 32篇 |
1991年 | 33篇 |
1990年 | 47篇 |
1989年 | 26篇 |
1988年 | 54篇 |
1987年 | 30篇 |
1986年 | 32篇 |
1985年 | 41篇 |
1984年 | 31篇 |
1983年 | 24篇 |
1982年 | 21篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 21篇 |
1978年 | 17篇 |
1977年 | 23篇 |
1975年 | 11篇 |
1974年 | 20篇 |
1973年 | 12篇 |
1970年 | 9篇 |
1966年 | 15篇 |
排序方式: 共有2079条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
5.
6.
A 68-year-old man receiving long-term therapy with oral sustained-release theophylline 450 mg twice/day was admitted to the hospital after failing treatment with azithromycin for an acute exacerbation of obstructive lung disease. Peak serum theophylline concentration was 20 μg/ml (normal 10–20 μg/ml). Azithromycin was discontinued and the theophylline dosage reduced by 33%. The subsequent 80% decrease in serum theophylline to 4.6 μg/ml was unexpectedly large. Two rechallenges produced similar transient depressions of serum theophylline concentrations after withdrawal of azithromycin, suggesting an interaction. Withdrawal of azithromycin may leave an increased number of active enzyme sites available as the drug is cleared from the system. In some circumstances, it may be useful for pharmacokinetic interaction studies to continue measuring concentrations after the suspected interacting agent is stopped. 相似文献
7.
8.
9.
Inhibition of 2-nitropropane-induced rat liver DNA and RNA damage by benzyl selenocyanate 总被引:5,自引:2,他引:3
We observed that pretreatment of male F344 rats with benzyl selenocyanate,
a versatile organoselenium chemopreventive agent in several animal model
systems, decreases the levels of DNA and RNA modifications produced in the
liver by the hepatocarcinogen 2- nitropropane. To clarify the mechanisms
involved, we pretreated male F344 rats with either benzyl selenocyanate,
its sulfur analog benzyl thiocyanate, phenobarbital or cobalt
protoporphyrin IX; the latter is a depletor of P450. We then determined (1)
the ability of liver microsomes to denitrify 2-nitropropane, (2) effects on
2-nitropropane- induced liver DNA and RNA modifications and (3) amount of
nitrate excreted in rat urine following administration of the carcinogen.
Pretreatment with benzyl selenocyanate or phenobarbital increased the
denitrification activity of liver microsomes by 217 and 765%, respectively,
increased liver P4502B1 by 31- and 435-fold, respectively, decreased the
levels of 2-nitropropane-induced modifications in liver DNA (29-70% and
17-30%, respectively) and RNA (67-85% and 30-50%, respectively), and
increased the 24-h urinary excretion of nitrate by 157 and 209%,
respectively. Pretreatment with benzyl thiocyanate had no significant
effect on any of these parameters. Pretreatment with cobalt protoporphyrin
IX decreased liver P4502B 1 by 87%, decreased the denitrification activity
of liver microsomes by 76%, decreased the 24 h urinary excretion of nitrate
by 88.5%, but increased the extent of 2-nitropropane-induced liver nucleic
acid modifications by 17-67%. These results indicate that the metabolic
sequence from 2-nitropropane to the reactive species causing DNA and RNA
modifications does not involve the removal of the nitro group. Moreover,
they suggest that benzyl selenocyanate inhibits 2-NP-induced liver nucleic
acid modifications in part by increasing its detoxication through induction
of denitrification, although it is evident that other mechanisms must also
be involved.
相似文献
10.
Acute psychotropic effects of bilateral subthalamic nucleus stimulation and levodopa in Parkinson's disease. 总被引:9,自引:0,他引:9
Aurélie Funkiewiez Claire Ardouin Paul Krack Valérie Fraix Nadège Van Blercom Jing Xie Elena Moro Alim-Louis Benabid Pierre Pollak 《Movement disorders》2003,18(5):524-530
High-frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves the motor symptoms of Parkinson's disease (PD). Opposite changes in mood, such as mania or depression, have been reported after surgery, but it is not known whether these side effects are specifically related to STN DBS. To learn whether STN DBS also influences the limbic loop, we investigated acute subjective psychotropic effects related to levodopa or bilateral STN DBS. After a median postoperative follow-up of 12 months, 50 PD patients completed the Addiction Research Center Inventory (ARCI), assessing subjective psychotropic effects in four conditions: off-drug/on-stimulation; off-drug/off-stimulation; on-drug/off-stimulation; and on-drug/on-stimulation. Both levodopa and STN DBS improved all the ARCI subscales, indicating subjective feelings of well being, euphoria, increase in motivation, and decrease in fatigue, anxiety, and tension. A suprathreshold dose of levodopa was significantly more effective than STN DBS, using the same electrical parameters as for chronic stimulation, on four of the five ARCI subscales. We concluded that 1) both STN DBS and levodopa have synergistic acute beneficial psychotropic effects in PD, 2) the psychotropic effects of both treatments need to be considered in the long-term management of chronic STN DBS, and 3) the results indicate an involvement of the limbic STN in mood disorders of PD. 相似文献