首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3143篇
  免费   260篇
  国内免费   115篇
耳鼻咽喉   5篇
儿科学   9篇
妇产科学   28篇
基础医学   312篇
口腔科学   86篇
临床医学   161篇
内科学   233篇
皮肤病学   94篇
神经病学   97篇
特种医学   41篇
外科学   184篇
综合类   472篇
现状与发展   1篇
预防医学   619篇
眼科学   38篇
药学   569篇
中国医学   339篇
肿瘤学   230篇
  2024年   3篇
  2023年   38篇
  2022年   91篇
  2021年   132篇
  2020年   107篇
  2019年   96篇
  2018年   86篇
  2017年   95篇
  2016年   108篇
  2015年   127篇
  2014年   174篇
  2013年   236篇
  2012年   151篇
  2011年   221篇
  2010年   170篇
  2009年   185篇
  2008年   198篇
  2007年   208篇
  2006年   139篇
  2005年   131篇
  2004年   124篇
  2003年   93篇
  2002年   75篇
  2001年   66篇
  2000年   63篇
  1999年   39篇
  1998年   55篇
  1997年   43篇
  1996年   27篇
  1995年   26篇
  1994年   14篇
  1993年   20篇
  1992年   17篇
  1991年   9篇
  1990年   7篇
  1989年   10篇
  1988年   5篇
  1987年   3篇
  1985年   8篇
  1984年   29篇
  1983年   16篇
  1982年   15篇
  1981年   6篇
  1980年   8篇
  1979年   13篇
  1978年   6篇
  1977年   5篇
  1976年   6篇
  1975年   3篇
  1974年   5篇
排序方式: 共有3518条查询结果,搜索用时 312 毫秒
91.
92.
The effects of acetylcholine on the spontaneous activity of the AV node of dog hearts were studied by recording transmembrane potentials of its fibers. Action potentials of most nodal fibers were characterized by prominent phase 4 depolarization and a smooth transition from phases 4 to 0. On the isolated AV nodes, acetylcholine at 1.0 μg/m1 suppressed the rate of phase 4 depolarization and increased the amplitude of the maximum diastolic potential, resulting in a slowing of spontaneous activity. At 2.0 μg/m1, spontaneous activity was completely suppressed. In comparison, spontaneous activity of the isolated His bundle was relatively insensitive to the suppressive effect of acetylcholine at the same concentrations. In the AV node-His bundle preparations in which the AV node was the pacemaker, acetylcholine decreased spontaneous activity by suppressing the phase 4 depolarization of the nodal fibers and shifted the pacemaker of the preparation to the His bundle. The findings provide a basis for predicting that under strong vagal influence, the automaticity of the AV node will be suppressed and the pacemaker of the junctional rhythm will be located at the His bundle.  相似文献   
93.
目的:提高目前国内教师职业心理健康水平,促进其职业健康,从而对学生的心理健康起到积极的影响作用。方法:尝试以格林模式为理论框架探索有效可行的教师职业心理健康干预模式,运用格林模式促进教师职业心理健康。结果:教师职业心理健康知识缺乏(倾向因素),目前没有系统的、持续的职业心理健康促进模式(促成因素)和良好的职业心理健康支持系统社会支持系统(强化因素)。结论:应运用格林模式从多个方面对目前教师职业心理健康存在的问题进行解读,然后去分析其发生的根本原因,进而有针对性地制定相应解决的办法。教师职业心理问题的预防应分为三级预防;教师职业心理健康问题的预防与化解可分为个人干预或组织干预。  相似文献   
94.
Compared with abundant catechins, strictinin is a minor constituent in teas and has been demonstrated to possess inhibitory potency on influenza virus. In this study, strictinin was found as the major phenolic compound in Pu’er teas produced from leaves and buds of wild trees. Due to its thermal instability, strictinin, in tea infusion or in an isolated form, was completely decomposed to ellagic acid and gallic acid after being autoclaved for 7 minutes. A plaque reduction assay was employed to compare the relative inhibitory potency between strictinin and its thermally degraded products against human influenza virus A/ Puerto Rico/8/34. The results showed that the antiviral activity of ellagic acid regardless of the presence or absence of gallic acid was significantly higher than that of strictinin. Thermal degradation of strictinin to ellagic acid and gallic acid seems to be beneficial for the preparation of Pu’er teas in terms of enhancing antiviral activity.  相似文献   
95.
Chun Mee tea is a kind of green tea produced in China mainly for export purposes. Foam quantity is usually used as an index for evaluating the quality of Chun Mee tea. In the current study, we compared the concentrations of total saponin and flavonoids between foamy and low-foam Chun Mee tea. Our research confirmed that the total saponin and O-glycosylated flavonoid concentrations were related to the foam quantity of Chun Mee teas. We also studied the short-term safety effects of extract supplementation with foamy and low-foam Chun Mee tea in rats by routine blood tests and analysis of liver and kidney function, and blood lipids. Our results showed that both types of tea extract supplementations did not cause any observable adverse effects or impair either liver or kidney function. Additionally, this study confirmed the beneficial effects of Chun Mee tea extract supplementation on the decrease of total plasma cholesterol.  相似文献   
96.
The present study was undertaken to investigate the food–drug interaction of carbamazepine (CBZ). Common fruit juices [grapefruit juice (GFJ), lime juice (LJ)], known to inhibit the enzyme cytochrome P450 3A4 (CYP3A4), and some widely consumed beverages [milk (M), black tea (BT)] were involved in this study in the presence of CBZ, as might happen during clinical therapy. The effects of the beverages on the pharmacokinetics and drug-induced toxicity of CBZ was observed after concomitant administration for a period of 28 days. Accordingly, the influence of altered bioavailability of CBZ on its antiepileptic activity was investigated. A significant shift in the Cmax as well as Tmax of CBZ was observed in the presence of LJ and GFJ. This increase in bioavailability significantly enhanced hepatotoxicity and delayed the onset of tremor and piloerection against pentylene tetrazole (PTZ)-induced seizure in experimental animals. However, increased toxicity of CBZ was found to be absent with BT. Thus, from our observation, LJ or GFJ in the presence of CBZ significantly increased the bioavailability of CBZ, which might lead to increased toxicity and antiepileptic activity of the drug.  相似文献   
97.
We have utilised a transgenic reporter mouse in which green fluorescent protein (GFP) expression is driven by the orexin-1 receptor (OX1R) promoter to systematically map the distribution of OX1R-expressing neurons throughout the mouse forebrain and rostral brainstem. GFP labelling was observed in perikarya and fibres in an extensive range of brain loci encompassing the olfactory and cerebral cortices, dorsal and ventral pallidum, hippocampus, amygdaloid regions, septal areas, thalamic nuclei, hypothalamic nuclei and several brainstem regions, consistent with previous studies of OX1R mRNA expression. This is the first study to systematically characterise the neuroanatomical distribution of OX1R in the OX1R-eGFP mouse, confirming its veracity as a faithful reporter of OX1R expression and utility for future studies assessing the role of OX1R in more complex behaviours.  相似文献   
98.
Despite all the emphasis laid today on the green economy, occupational health and safety (OHS) issues have still been talked only limitedly, as already noted in previous studies and literature reviews. The Department of Occupational and Environmental Medicine, Epidemiology and Hygiene of the Italian Workers’ Compensation Authority (INAIL) has conducted a survey among some Italian stakeholders, social partners, institutions and “green” businesses to gather their perceptions of the potential effects of green jobs on OHS, particularly in the renewable energy sector. The survey involved a sample of 61 stakeholders in the following categories: institutions (11), trade unions (11), employers’ organizations (13), businesses (11), research (15). Participation in this survey of national stakeholders who have a central role in the development and management of policies on renewable energy and OHS, allowed to analyze in depth the fundamental aspects for a fair transition towards green economy. Also, the good agreement among respondents brought to light quite clearly the main critical points as regards the OHS implications of green work in Italy, and pointed to the principal policies to be adopted to safeguard workers’ health and safety.  相似文献   
99.
The P, Na, K, Ca, Mg, Fe, Cu, Zn and Mn concentrations were determined in seventy-three samples of seaweeds belonging to different genera (classified as brown, red and green seaweeds), which were collected from three zones in the sub-Antarctic ecoregion of Magallanes (Chile). There were clear differences in the concentrations between the considered genera. Brown seaweed had the highest mean K (31.4 g/kg) and Ca (10.3 g/kg) concentrations compared with red (14.1 g/kg for K and 3.11 g/kg for Ca) and green (13.9 g/kg for K and 7.58 g/kg for Ca) seaweed, and green seaweed had the highest mean Mg (15.0 g/kg), Fe (1260 mg/kg) and Cu (7.46 mg/kg) concentrations. The consumption of a serving (8 g) from of the three groups of brown, red and green seaweed is a good source of Fe, Mg and Mn (>25% of the Dietary Recommended Intake). Significant differences were observed in the mean concentrations of all the minerals and trace elements, except for Fe, Cu and Mn, between the three collection zones. Factor and discriminant analysis were used to differentiate the type of seaweed and sampling zone. Besides which, good classifications were obtained according to the type of seaweed using discriminant analysis.  相似文献   
100.
经方大家胡希恕先生与冯世纶教授对《伤寒论》的六经进行了重新解读,认为六经来自八纲,系表、里、半表半里各分阴阳,即三阴三阳.提出辨证施治是于患病机体一般的规律反应的基础上,讲求疾病的通治方法.通过先辨八纲,再辨六经,最后辨方证,合理运用经方以提高临床疗效.验证于临床,应用经方小青龙汤治哮喘、厚朴生姜甘草半夏人参汤治脾虚腹胀、乌梅丸治慢性结肠炎等疑难杂症,均取得了满意疗效.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号