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   68252篇
  免费   4986篇
  国内免费   1917篇
耳鼻咽喉   519篇
儿科学   1561篇
妇产科学   2351篇
基础医学   7261篇
口腔科学   1384篇
临床医学   6370篇
内科学   7919篇
皮肤病学   933篇
神经病学   4356篇
特种医学   1781篇
外国民族医学   7篇
外科学   5227篇
综合类   10216篇
现状与发展   3篇
一般理论   6篇
预防医学   6708篇
眼科学   1797篇
药学   8127篇
  79篇
中国医学   5544篇
肿瘤学   3006篇
  2023年   1095篇
  2022年   1580篇
  2021年   2595篇
  2020年   2482篇
  2019年   3083篇
  2018年   2715篇
  2017年   2346篇
  2016年   2092篇
  2015年   2012篇
  2014年   4028篇
  2013年   4840篇
  2012年   3827篇
  2011年   4249篇
  2010年   3343篇
  2009年   3012篇
  2008年   2917篇
  2007年   2884篇
  2006年   2545篇
  2005年   2272篇
  2004年   1894篇
  2003年   1864篇
  2002年   1407篇
  2001年   1342篇
  2000年   1074篇
  1999年   978篇
  1998年   753篇
  1997年   737篇
  1996年   679篇
  1995年   795篇
  1994年   668篇
  1993年   554篇
  1992年   509篇
  1991年   457篇
  1990年   473篇
  1989年   414篇
  1988年   298篇
  1987年   261篇
  1986年   320篇
  1985年   637篇
  1984年   708篇
  1983年   519篇
  1982年   589篇
  1981年   516篇
  1980年   478篇
  1979年   405篇
  1978年   315篇
  1977年   306篇
  1976年   324篇
  1975年   252篇
  1974年   188篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
71.
目的制备美洲大蠊Periplaneta americana口腔原位温敏凝胶。方法采用自由基聚合法首次以N-异丙基丙烯酰胺(NNIPAM)和甲基丙烯酸羟丙酯(HPMA)合成聚(N-异丙基丙烯酰胺-甲基丙烯酸羟丙酯)[P(NNIPAM-HPMA)]作为温敏材料;通过冷溶法制备美洲大蠊口腔原位温敏凝胶,采用Box-Behnken设计响应面法,以溶蚀时间、胶凝时间为评价指标,在固定美洲大蠊提取物用量基础上,对羟丙基甲基纤维素(HPMC)、聚乙烯吡咯烷酮(PVP K30)、P(NNIPAM-HPMA)的用量进行优选。结果通过原位聚合法合成了P(NNIPAM-HPMA)温敏材料;并用响应面法优选了可用于口腔的美洲大蠊原位温敏凝胶的处方,优选的处方为美洲大蠊提取物10%、HPMC 3.0%、PVP K30 9.5%、P(NNIPAM-HPMA) 10.0%,其溶蚀时间为2 h,胶凝时间8~9 s。结论优选得到美洲大蠊口腔原位温敏凝胶,为美洲大蠊提取物的口腔原位局部的临床应用奠定了科学依据。  相似文献   
72.
《中国现代医生》2020,58(34):60-63
目的 通过检测老年轻度认知障碍(MCI)患者血清瘦素(LEP)、甲状腺激素水平,分析其与局部脑血流量(rCBF)的关系。方法 选择本院收治的128 例老年MCI 患者,另选健康者128 例作为对照组。检测血清LEP、甲状腺激素、大脑各区域rCBF 水平并分析其相关性。结果 老年MCI 组患者左右侧额叶、右侧颞叶、左侧顶叶、左右侧基底节区域脑血流量[(43.81±8.62)mL/(100 g·min)、(43.24±7.93)mL/(100 g·min)、(45.14±6.98)mL/(100 g·min)、(45.86±6.77)mL/(100 g·min)、(67.95±8.52)mL/(100 g·min)、(68.36±8.34)mL/(100 g·min)]低于对照组[(46.39±8.31)mL/(100 g·min)、(46.52±8.56)mL/(100 g·min)、(47.37±7.04)mL/(100 g·min)、(48.25±6.98)mL/(100 g·min)、(70.34±8.96)mL/(100 g·min)、(70.58±8.57)mL/(100 g·min)](P<0.05)。老年MCI 组患者血清LEP、T3、FT3 水平[(4.87±1.56)μg/L、(1.21±0.16)nmol/L、(3.04±0.36)pmol/L]低于对照组[(11.45±3.92)μg/L、(1.68±0.21)nmol/L、(4.82±1.21)pmol/L](P<0.05),TSH 水平为(2.78±0.75)IU/mL,高于对照组的(1.13±0.38)IU/mL(P<0.05)。老年MCI 患者血清LEP 水平与左侧额叶、右侧颞叶、左侧顶叶rCBF 呈正相关(r=0.452、0.537、0.544,P 均<0.05),T3 水平与左侧额叶、右侧颞叶rCBF 呈正相关(r=0.427、0.521,P 均<0.05),FT3 水平与右侧颞叶rCBF 呈正相关(r=0.492,P<0.05),TSH 水平与左侧额叶、右侧颞叶rCBF 呈负相关(r=-0.463、-0.489,P 均<0.05)。结论 老年MCI 患者血清中LEP、T3、FT3 水平降低,TSH 水平升高,且与不同区域rCBF 有相关性,可通过调控脑血管功能影响rCBF 变化水平。  相似文献   
73.
目的:研究乙酰紫草素(ASK)对人前列腺癌PC-3细胞的诱导凋亡作用及相关的分子机制。方法:利用CCK-8实验检测ASK对体外培养PC-3细胞的杀伤作用;利用流式细胞术实验检测ASK处理后PC-3细胞凋亡情况;利用Western blotting检测凋亡蛋白和AKT信号通路蛋白的表达。结果:CCK-8实验证明ASK能够以时间和浓度依赖性抑制前列腺癌PC-3细胞的增殖;流式细胞术实验证明ASK能够诱导人前列腺癌PC-3细胞线粒体依赖性凋亡;Western blotting证明ASK能够有效抑制前列腺癌PC-3细胞中的AKT信号通路。结论:ASK能够有效抑制人前列腺癌PC-3细胞增殖,并能够有效诱导PC-3细胞发生线粒体依赖性凋亡,其机制可能是通过调控PI3K/Akt信号通路来实现,说明ASK具有一定的抗前列腺癌的潜力。  相似文献   
74.
75.
76.
Morbidity and mortality among children is usually the result of trauma. Because a child’s face is retruded relative to the protecting skull, has a thicker layer of adipose tissue, more elastic bones, flexible sutures lines, the presence of tooth buds within the jaws, and the lack of pneumatisation of the sinuses, the facial bones fracture less commonly than in adults. Our aim was to assess the patterns of such fractures in children who presented to the department of Oral and Maxillofacial Surgery, King Edward Medical University/Mayo Hospital Lahore, Pakistan. All 535 eligible children between the ages of 1-16 years who presented during the two years December 2009 - December 2011 were included in the study. Facial fractures were diagnosed by clinical examination, plain radiographs, and computed tomography, and the pattern of fractures of the facial bones including the frontal bone, orbital bones, maxilla, zygoma, naso-orbito-ethmoidal complex, mandible, and dentoalveolar region was documented. The male:female ratio was 2:1 with 369 male (70%) and 166 female (31%) patients. Fall was the cause in 212 (39%), and in 167 (31%) it was road traffic accidents, while sports were the cause in 135 (25%). The naso-orboto-ethmoid complex was fractured in 37 cases (7%) while 104 children (19%) presented with isolated fractures of the zygomatic bone. The maxilla was fractured in 195 cases (36%), the mandible in 380 (71%), and dentoalveolar trauma was the cause in 256 (50%). The mandible was the bone that was most often fractured (mostly in boys and usually as a result of falls during summer vacations), with the peak occurring in those aged 8-12 years.  相似文献   
77.
78.
Background:In recent years, the incidence rate of children with severe Mycoplasma pneumoniae pneumonia (SMPP) is increasing, which poses a great threat to children''s life and safety. There are some limitations in the existing drugs for the treatment of SMPP, and the supplementary and alternative therapy of SMPP plays an irreplaceable role in the treatment of this disease. This study will evaluate the efficacy and safety of various complementary and alternative therapies for SMPP by means of mesh meta-analysis. In order to provide the basis for clinical rational use.Methods:Two researchers will independently and comprehensively searched the Cochrane Central controlled trials registry, Cochrane Library, PubMed, web of science, EMBASE, CNKI, and Wanfang database to collect randomized controlled trials (RCT) studies on complementary and alternative therapies for SMPP. And the relevant references included in the systematic review/meta-analysis are screened. The retrieval time limit is from the establishment of the database to November 2020. We will use Revman 5.3 software for meta-analysis and use grade to grade the quality of evidence in the net meta-analysis (NMA).Results:The aim of this study was to compare the efficacy and safety of different complementary and alternative therapies in the treatment of SMPP, with a view to evaluating and ranking different interventions.Conclusion:The supplement and replacement therapy of SMPP can improve the clinical efficacy, relieve the clinical symptoms, improve the quality of life of children, and reduce adverse reactions, which can provide strong support for the rational use of clinicians.INPLASY registration number:INPLASY2020110079.  相似文献   
79.
《Clinical neurophysiology》2021,132(7):1622-1635
ObjectiveTo assess whether ictal electric source imaging (ESI) on low-density scalp EEG can approximate the seizure onset zone (SOZ) location and predict surgical outcome in children with refractory epilepsy undergoing surgery.MethodsWe examined 35 children with refractory epilepsy. We dichotomized surgical outcome into seizure- and non-seizure-free. We identified ictal onsets recorded with scalp and intracranial EEG and localized them using equivalent current dipoles and standardized low-resolution magnetic tomography (sLORETA). We estimated the localization accuracy of scalp EEG as distance of scalp dipoles from intracranial dipoles. We also calculated the distances of scalp dipoles from resection, as well as their resection percentage and compared between seizure-free and non-seizure-free patients. We built receiver operating characteristic curves to test whether resection percentage predicted outcome.ResultsResection distance was lower in seizure-free patients for both dipoles (p = 0.006) and sLORETA (p = 0.04). Resection percentage predicted outcome with a sensitivity of 57.1% (95% CI, 34–78.2%), a specificity of 85.7% (95% CI, 57.2–98.2%) and an accuracy of 68.6% (95% CI, 50.7–83.5%) (p = 0.01).ConclusionIctal ESI performed on low-density scalp EEG can delineate the SOZ and predict outcome.SignificanceSuch an application may increase the number of children who are referred for epilepsy surgery and improve their outcome.  相似文献   
80.
Adenoid cystic carcinoma (ACC) is an aggressive, rare, malignant tumour that accounts for about 1% of all head and neck neoplasms and 10% of all salivary gland tumours. It is characterised by frequent local recurrences and distant metastases. Growth is slow but relentless, and progression poses a challenge to head and neck clinicians. Many small retrospective studies have described its clinical management, but the lack of multicentre, randomised, controlled trials has resulted in inconsistencies in management globally. We have focused on three key management-related controversies: the role of elective neck dissection (END) for the N0 neck; the role of adjuvant treatment or radiotherapy; and finally, the follow-up protocol, particularly cross-sectional surveillance imaging of the full body or chest computed tomography (CT) alone, and options for treatment if metastases are found. The paucity of published studies may reflect the inconsistencies that exist in the management of ACC of the head and neck in the UK. The collaboration of head and neck centres would, we think, help to correct the imbalance in these three domains of care.  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