全文获取类型
收费全文 | 1697篇 |
免费 | 86篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 74篇 |
儿科学 | 104篇 |
妇产科学 | 58篇 |
基础医学 | 183篇 |
口腔科学 | 48篇 |
临床医学 | 86篇 |
内科学 | 311篇 |
皮肤病学 | 38篇 |
神经病学 | 69篇 |
特种医学 | 36篇 |
外科学 | 359篇 |
综合类 | 28篇 |
一般理论 | 1篇 |
预防医学 | 54篇 |
眼科学 | 32篇 |
药学 | 111篇 |
中国医学 | 1篇 |
肿瘤学 | 194篇 |
出版年
2023年 | 6篇 |
2022年 | 23篇 |
2021年 | 66篇 |
2020年 | 27篇 |
2019年 | 34篇 |
2018年 | 38篇 |
2017年 | 39篇 |
2016年 | 42篇 |
2015年 | 44篇 |
2014年 | 69篇 |
2013年 | 68篇 |
2012年 | 110篇 |
2011年 | 113篇 |
2010年 | 47篇 |
2009年 | 46篇 |
2008年 | 91篇 |
2007年 | 81篇 |
2006年 | 89篇 |
2005年 | 97篇 |
2004年 | 82篇 |
2003年 | 74篇 |
2002年 | 56篇 |
2001年 | 46篇 |
2000年 | 52篇 |
1999年 | 36篇 |
1998年 | 13篇 |
1997年 | 13篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 33篇 |
1991年 | 21篇 |
1990年 | 13篇 |
1989年 | 17篇 |
1988年 | 14篇 |
1987年 | 26篇 |
1986年 | 21篇 |
1985年 | 17篇 |
1984年 | 7篇 |
1983年 | 12篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 7篇 |
1972年 | 6篇 |
1967年 | 4篇 |
1966年 | 3篇 |
排序方式: 共有1787条查询结果,搜索用时 15 毫秒
1.
Elizabeth D. Krebs Robert B. Hawkins J. Hunter Mehaffey Clifford E. Fonner Alan M. Speir Mohammed A. Quader Jeffrey B. Rich Leora T. Yarboro Nicholas R. Teman Gorav Ailawadi 《The Journal of thoracic and cardiovascular surgery》2019,157(4):1533-1542.e2
Objectives
Expedient extubation after cardiac surgery has been associated with improved outcomes, leading to postoperative extubation frequently during overnight hours. However, recent evidence in a mixed medical-surgical intensive care unit population demonstrated worse outcomes with overnight extubation. This study investigated the impact of overnight extubation in a statewide, multicenter Society of Thoracic Surgeons database.Methods
Records from 39,812 patients undergoing coronary artery bypass grafting or valve operations (2008-2016) and extubated within 24 hours were stratified according to extubation time between 06:00 and 18:00 (day) or between 18:00 and 6:00 (overnight). Outcomes including reintubation, mortality, and composite morbidity-mortality were evaluated using hierarchical regression models adjusted for Society of Thoracic Surgeons predictive risk scores. To further analyze extubation during the night, a subanalysis stratified patients into 3 groups: 06:00 to 18:00, 18:00 to 24:00, and 24:00 to 06:00.Results
A total of 20,758 patients were extubated overnight (52.1%) and were slightly older (median age 66 vs 65 years, P < .001) with a longer duration of ventilation (4 vs 7 hours, P < .001). Day and overnight extubation were associated with equivalent operative mortality (1.7% vs 1.7%, P = .880), reintubation (3.7% vs 3.4%, P = .141), and composite morbidity-mortality (8.2% vs 8.0%, P = .314). After risk adjustment, overnight extubation was not associated with any difference in reintubation, mortality, or composite morbidity-mortality. On subanalysis, those extubated between 24:00 and 06:00 exhibited increased composite morbidity-mortality (odds ratio, 1.18; P = .001) but no difference in reintubation or mortality.Conclusions
Extubation overnight was not associated with increased mortality or reintubation. These results suggest that in the appropriate clinical setting, it is safe to routinely extubate cardiac surgery patients overnight. 相似文献2.
3.
4.
Species differences in the hydrolysis of 2-cyanoethylene oxide, the epoxide metabolite of acrylonitrile 总被引:2,自引:1,他引:1
The carcinogenic effects of acrylonitrile in rats are believedto be mediated by its DNA-reactive epoxide metabolite, 2-cyanoethyleneoxide (CEO). Previous studies have shown that conjugation withglutathione is the major detoxication pathway for both acrylonitrileand CEO. This study investigated the role of epoxide hydrolasein the hydrolysis of CEO by HPLC analysis of the products from[2,3-14C]CEO. CEO is a relatively stable epoxide with a half-lifeof 99 min at 37°C in sodium phosphate buffer (0.1 M), pH7.3. Incubation with hepatic microsomes or cytosols from maleF-344 rats or B6C3F1 mice did not enhance the rate of hydrolysisof CEO (0.69 nmol/min). Human hepatic microsomes significantlyincreased the rate of hydrolysis of CEO, whereas human hepaticcytosols did not. Human hepatic microsomal hydrolysis activitywas heat-sensitive and potently inhibited by 1,1,1-trichloropropeneoxide (IC50 of 23 µM), indicating that epoxide hydrolasewas the catalyst. The hydrolysis of CEO catalyzed by hepaticmicrosomes from six individuals exhibited normal saturationkinetics with KM ranging from 0.6 to 3.2 mM and V max from 8.3to 18.8 nmol hydrolysis products/min/mg protein. Pretreatmentof rodents with phenobarbital or acetone induced hepatic microsomalhydrolysis activity toward CEO, whereas treatment with ß-naphthoflavone,dexamethasone or acrylonitrile itself was without effect. Thesedata show that humans possess an additional detoxication pathwayfor CEO that is not active in rodents (but is inducible). Thepresence of an active epoxide hydrolase hydrolysis activitytoward CEO in humans should be considered in assessments ofcancer risk from acrylonitrile exposure. 相似文献
5.
6.
7.
R Guleria Y K Batra B K Sharma S K Jindal 《The Indian journal of chest diseases & allied sciences》1992,34(3):149-152
A patient of chronic obstructive pulmonary disease (COPD) with cor-pulmonale and chronic respiratory failure, who was given intermittent positive pressure ventilation at home, is reported. The patient did remarkably well on home mechanical ventilatory support. We believe this to be the first case report of domiciliary mechanical ventilation in a patient of COPD from India. 相似文献
8.
M Hidiroglou T R Batra L F Laflamme F Markham 《International journal for vitamin and nutrition research. Internationale Zeitschrift für Vitamin- und Ern?hrungsforschung. Journal international de vitaminologie et de nutrition》1992,62(4):308-311
The effect of vitamin E injections on immune responses of calves was investigated. Treatments were: 0, 900, 1800 and 2700 IU of D-alpha-tocopherol given by injection starting at birth and then a 3 wk interval until the age of 12 wk. Plasma vitamin E levels were significantly higher for supplemented calves than control calves at any of the sampling times. There were no significant differences in the concentrations of immunoglobulin IgG1, IgG2 and titre to Keyhole Limpet Haemocyanin among treatments. However, the general trend was to have higher concentrations of IgG1 and IgG2 with an increase in the levels of vitamin E. Immunoglobulin IgM was significantly higher for calves supplemented with 2700 IU of vitamin E than control calves. 相似文献
9.
Adult worms of Acanthocheilonema viteae were found to be susceptible to the reactive oxygen intermediates (ROI) generated by the xanthine-xanthine oxidase (X-XO) system. The damage caused by this system was completely abolished by superoxide dismutase (SOD) and catalase but not by mannitol. The results, therefore, suggest that superoxide anions (O2-) and hydrogen peroxide (H2O2) alone or in combination might be toxic to the filariid. A. viteae exhibited the presence of an active enzyme system to protect itself against the oxidants. SOD and catalase were present in high levels of activities and appeared to constitute the major defence system. The role of glutathione peroxidase (GPx), on the other hand, seemed less important due to the weak activities of glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PDH). A. viteae also released SOD, catalase and GPx in the ambient medium, which appear useful in protecting the filariid against ROI generated by the host in the immediate surroundings of the parasite. Antifilarial agents, diethylcarbamazine (DEC) and 2,2'-dicarbomethoxylamino-5,5'-dibenzimidazolyl ketone (82/437) appreciably inhibited catalase and GPx of A. viteae. Inhibition of these enzymes appears to render the parasite prone to H2O2 toxicity leading to death. No adverse effect on antioxidant enzymes of liver, lungs and subcutaneous tissue of Mastomys natalensis recorded as a result of exposure to 82/437 suggests a non-toxic nature to the compound. 相似文献
10.