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   16383篇
  免费   1289篇
  国内免费   136篇
耳鼻咽喉   127篇
儿科学   501篇
妇产科学   454篇
基础医学   2230篇
口腔科学   322篇
临床医学   1531篇
内科学   3210篇
皮肤病学   230篇
神经病学   1184篇
特种医学   571篇
外科学   2762篇
综合类   664篇
一般理论   5篇
预防医学   1039篇
眼科学   409篇
药学   996篇
  1篇
中国医学   96篇
肿瘤学   1476篇
  2023年   148篇
  2022年   166篇
  2021年   428篇
  2020年   289篇
  2019年   380篇
  2018年   449篇
  2017年   343篇
  2016年   359篇
  2015年   457篇
  2014年   560篇
  2013年   702篇
  2012年   1050篇
  2011年   1139篇
  2010年   686篇
  2009年   608篇
  2008年   907篇
  2007年   899篇
  2006年   878篇
  2005年   878篇
  2004年   852篇
  2003年   772篇
  2002年   714篇
  2001年   610篇
  2000年   499篇
  1999年   416篇
  1998年   146篇
  1997年   141篇
  1996年   116篇
  1995年   104篇
  1994年   81篇
  1993年   71篇
  1992年   207篇
  1991年   194篇
  1990年   187篇
  1989年   194篇
  1988年   151篇
  1987年   166篇
  1986年   130篇
  1985年   94篇
  1984年   74篇
  1983年   57篇
  1982年   29篇
  1981年   46篇
  1980年   35篇
  1979年   65篇
  1978年   42篇
  1977年   48篇
  1976年   32篇
  1975年   30篇
  1973年   27篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Phytonutrients extracted from natural resources are receiving much attention among researchers due to their highly antioxidative characteristics which prevent several degenerative diseases including cardiovascular diseases and cancers. These nutraceutical compounds can be used in food, pharmaceutical and cosmetic products as natural antioxidants, preservatives, colourants and functional foods. Huge volume of food wastes are generated from the processing industry and these low-value food residues are rich in various phytonutrients worth recovering. This approach of valorisation reduces the generation of food wastes and is cost-effective considering the cheap feedstock, reduced waste management expenses and high market value of extracted compounds. In light of the health and safety risks posed by commonly used organic extraction solvents derived from the petrochemical industry, there is a need to recover the phytonutrients using green, sustainable and efficient solvents that are safe for human consumption. This work discusses ethyl lactate as a safe, green, efficient and potentially cheap solvent to recover phytonutrients from fruit and vegetable by-products. Ethyl lactate is compared with other organic solvents commonly used from the aspects of safety, environmental impacts and efficiency. Current challenges when employing ethyl lactate are also discussed.  相似文献   
4.
5.
6.
目的:评价东部身体-智力-精神(EBMS)群体干预对进行体外受精(IVF)的中国妇女焦虑缓解的作用。设计:随机对照研究。机构:三级辅助生殖机构。受试者:227例接受第1个IVF周期治疗的妇女。干预:干预组(n=69)接受4次EBMS群体咨询,而对照组(n=115)无任何干预。主要观察指标:状态-特质焦虑问卷。结果:与对照组相比,干预组在干预后状态焦虑平均分显著下降。每组移植同样数目的卵子,但干预组没有明显更高妊娠率的倾向。  相似文献   
7.
To assess the vascular involvement of renin-angiotensin system inhibition in human hypertension, acute effects of intravenous enalaprilat on brachial artery diameter, blood flow, and blood velocity were investigated in hypertensive patients by pulsed Doppler technique and compared with effects of saline vehicle. Compared with saline vehicle, enalaprilat reduced blood pressure (P less than 0.001) and increased brachial arterial diameter (P less than 0.01) and brachial blood flow (P less than 0.01). Enalaprilat effect on arterial pulse pressure was dependent on preinjection pulse pressure (r = -0.76; P less than 0.001), but its effect on mean blood pressure was not dependent on preinjection mean blood pressure. On the other hand, enalaprilat effect on arterial blood flow was negatively correlated with preinjection blood pressure (r = -0.64; P less than 0.02). The findings point to different responses of large and small arteries to intravenous enalaprilat.  相似文献   
8.
9.
Background and objective  The purpose of this study is to assess whether Chinese children with high apnea–hypopnea index (AHI) are sleepier by a modified Epworth Sleepiness Scale (ESS). Materials and methods  Records were retrospectively reviewed. We included children who were between 3 and 12 years old, admitted for overnight polysomnogram because of suspected obstructive sleep apnea syndrome (OSAS). A modified ESS was used to assess excessive daytime sleepiness (EDS) of the children. Results  One hundred ninety-two Chinese children were included. Children with high AHI, defined as AHI > 5.0, were sleepier than children with AHI less than or equal to 5. After adjustment by age, gender, and obesity, children with high AHI remained significantly sleepier. Modified ESS was significantly correlated with AHI (rho = 0.124, 95% CI = 0.004–0.281). Modified ESS score of >8 was the best cutoff point with the sensitivity and specificity of 0.29 and 0.91, respectively. The odds ratio of children with modified ESS > 10 having high AHI was 4.231 (95%CI = 1.248 to 14.338) and children with modified ESS > 8 had the highest odds ratio, 4.295(95%CI = 1.66 to 11.1), of having high AHI. Conclusion   Chinese children with high AHI appear to be sleepier than children with low AHI. Children with suspected OSAS and high modified ESS, i.e., ESS > 8, had significantly higher odds ratio of having high AHI. Increased sleepiness is a specific but not a sensitive symptom in snoring children with high AHI. Screening for EDS in snoring children may help us identify those with high AHI and prioritize the management of those children. All authors worked and the study was carried out in Kwong Wah Hospital in Hong Kong. There was no conflict of interest and no specific source of funding for the study.  相似文献   
10.
Following an encephalopathic illness, a 13-year-old Chinese boy had a partial form of Klüver-Bucy syndrome with emotional disturbance, recent memory loss, hypersexuality, and polyphagia. Other unusual features included narcolepsy, polydipsia, and polyuria. Virologic studies failed to incriminate the etiologic agent, including herpes simplex virus. Brain biopsy of the frontal lobe demonstrated Alzheimer type II astrocytosis.  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