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   81750篇
  免费   7461篇
  国内免费   5441篇
耳鼻咽喉   850篇
儿科学   885篇
妇产科学   1226篇
基础医学   10588篇
口腔科学   1417篇
临床医学   10878篇
内科学   12179篇
皮肤病学   1026篇
神经病学   4502篇
特种医学   3085篇
外国民族医学   53篇
外科学   8477篇
综合类   10909篇
现状与发展   22篇
一般理论   22篇
预防医学   5050篇
眼科学   2981篇
药学   8538篇
  71篇
中国医学   4211篇
肿瘤学   7682篇
  2024年   221篇
  2023年   1100篇
  2022年   2736篇
  2021年   4114篇
  2020年   3007篇
  2019年   2899篇
  2018年   3089篇
  2017年   2557篇
  2016年   2654篇
  2015年   3822篇
  2014年   4776篇
  2013年   4192篇
  2012年   6207篇
  2011年   6654篇
  2010年   4104篇
  2009年   3105篇
  2008年   4306篇
  2007年   4166篇
  2006年   4281篇
  2005年   4101篇
  2004年   2803篇
  2003年   2560篇
  2002年   2105篇
  2001年   1798篇
  2000年   1795篇
  1999年   2068篇
  1998年   1308篇
  1997年   1278篇
  1996年   968篇
  1995年   914篇
  1994年   769篇
  1993年   489篇
  1992年   594篇
  1991年   503篇
  1990年   475篇
  1989年   413篇
  1988年   371篇
  1987年   291篇
  1986年   250篇
  1985年   213篇
  1984年   129篇
  1983年   88篇
  1982年   42篇
  1981年   51篇
  1980年   29篇
  1979年   63篇
  1978年   22篇
  1974年   27篇
  1973年   18篇
  1968年   16篇
排序方式: 共有10000条查询结果,搜索用时 421 毫秒
991.
In order to develop new anti-inflammatory agents having different action mechanisms compared with nonsteroidal and steroidal anti-inflammatory drugs, the culture broths of various actinomycetes isolated from soil were screened using anin vivo mouse ear edma assay and one strain (Streptomyces sp. MT 2705-4: KCTC 8651P) was selected. Activity-guided purification led to the isolation of a polyether compound, dianemycin. Topically, dianemycin showed a potent anti-inflammatory activity in mouse ear edema induced by croton-oil or arachidonic acid. ED(50) value of dianemycin was found to be 0.8 mg/ear compared to 0.4 mg/ear of prednisolone in croton-oil ear edema. However, dianemycin did not show the inhibitory activity in UV-erythema and delayed hypersensitivity reaction. These results indicate that dianemycin is a potential topical anti-inflammatory agent.  相似文献   
992.
Methicillin-resistant Staphylococcus aureus (MRSA) is a worldwide important pathogen in nosocomial infections. To investigate the extent of the problem in Taiwan, analysis for the period of 1981-1994 was carried out of prospective surveillance data from the National Taiwan University Hospital, a major university teaching hospital in Taiwan. The number of nosocomial MRSA infections increased from five in 1981 to 133 in 1994, and the incidence increased from 0.2 episodes/1000 discharges in 1981 to 2.9 episodes/1000 discharges in 1994. The most common infection site was surgical wounds, which accounted for 26.3% of total 577 episodes of nosocomial MRSA infections during the study period. However, bacteraemia has become more and more common during the past 14 years. MRSA infections occured more frequently in patients stayed in the burn unit and other intensive care units than in the general wards. Other than oxacillin, the resistance rate to many other antibiotics also increased in S. aureus strains causing nosocomial infections in this hospital. Vancomycin remained active to all these S. aureus strains, even until 1994.  相似文献   
993.
The localization of apolipoprotein E (ApoE) has been examined immunohistochemically in the autopsied brains of middle-aged and old-aged control subjects, with and without amyloid protein (A) deposits, and of Alzheimer's disease patients. Senile plaques were consistently labeled with ApoE antiserum even in the very early stage of senile plaque formation seen in the fifth decade. In the cerebellar molecular layer, small dots of ApoE immunoreactivity, which were prominent in the Alzheimer's disease subjects, were observed in addition to immunoreactivity in diffuse plaques. ApoE antisera labeled all of the extracellular neurofibrillary tangles (NFT), whereas only a small minority of extracellular NFT were positive for A. A punctate pattern of ApoE immunoreactivity was seen at the media of the meningeal vessels lacking amyloid, when senile plaques were present in the nearby cortex. In the early stage of amyloid angiopathy, the distribution of ApoE immunoreactivity was much more extensive than that of A positivity. These findings suggest that ApoE accumulates in the early stage of senile plaque formation and, furthermore, that ApoE accumulation precedes A deposition in extracellular NFT and amyloid angiopathy.  相似文献   
994.
The pulmonary absorption kinetics of a single molecular weight distribution (MWD) of fluorophore-labeled poly-,-[N(2-hydroxyethyl)-DL-aspartamide] (F-PHEA), a hydrophilic and biocompatible synthetic polypeptide, were studied in the isolated, perfused rat lung (iprl) as functions of administered polymer concentration, dose, vehicle, and presence and absence of fluorophore. The MWD was characterized before and after absorption by measurement of weight- and number-averaged molecular weights (M wand M n, respectively) using high-performance gel-permeation chromatography. Values for M w and M n were 8.6 and 5.3 kD before, and 6.7 and 4.7 kD after, absorption into the perfusate; there was no significant metabolism and the MWD of the absorbed polymer was independent of both dose and sampling time over a 3-hr period. F-PHEA failed to show any evidence of aggregation in solution or changes in dose distribution within the airways as functions of increasing polymer concentration and dose. A concentration ranging study indicated the presence of a saturable, carrier-mediated transport process for F-PHEA with a maximum absorption rate, V max, of approximately 180 µg or 0.027 µmol/hr. Coadministration of fluorophore-free PHEA was capable of depressing the absorption of F-PHEA. The transport process for F-PHEA appeared to have a molecular weight limit of about 7 kD for this hydrophilic polymer.  相似文献   
995.
The new bis-naphthalimide antitumor agent (R,R)2,2-[1,2-ethanediylbis[imino(1-methyl-2.1-ethanediyl)]-bis {5-nitro-1H-benz[de]-isoquinoline-1,3-2H) dione} dimethanesulfonate (DMP 840) was evaluated against parental and multidrug-resistant human KB cell lines in vitro and against these lines growing as xenografts in immunedeprived mice. In vitro, KB8-5 cells were 50-fold resistant to vincristine but only 16-fold resistant to DMP 840 as measured by clonogenic survival. For in vivo evaluation, DMP 840 was given by i. v. injection daily for 9 days or for 5 days/week for 2 consecutive weeks [(dx5)2]. In contrast to the cross-resistance of KB cell lines in vitro, both KB3-1 and KB8-5 tumors were highly and equally sensitive to DMP 840; only KB3-1 xenografts demonstrated sensitivity to vincristine, which was consistent with the in vitro results. DMP 840 was also evaluated against a panel of human tumors comprising colon adenocarcinoma and rhabdomyosarcoma xenografts. Against eight lines of colon adenocarcinoma, DMP 840 caused a high frequency of partial and complete regressions in two lines and significant inhibition of growth in two lines. DMP 840 caused complete regressions in five of six lines of advanced rhabomyosarcomas, demonstrating a broad range of effective dose levels. The pattern of activity against this tumor panel was similar but not identical to that of two inhibitors of topoisomerase I. There was no cross-resistance to DMP 840 in xenografts selected for resistance to vincristine or in a rhabdomyosarcoma selected for resistance to the topoisomerase I inhibitor topotecan. In contrast, a colon tumor selected for topotecan resistance was completely resistant to DMP 840. Slight cross-resistance to DMP 840 was demonstrated in a rhabdomyosarcoma xenograft that was selected for primary resistance to melphalan and was cross-resistant to topoisomerase I inhibitors. The pattern of activity and cross-resistance in these tumors was compared with that shown by two agents that inhibit topoisomerase I: topotecan and CPT-11.This work was supported in part by CA23099, Cancer Center Support (CORE) grant CA21675, The Du Pont Merck Pharmaceutical Company, and by American Lebanese Syrian Associated Charities (ALSAC)  相似文献   
996.
SEARCHFORHERPESSIMPLEXVIRUSTYPE2(HSV-2)ANDHUMANPAPILLOMAVIRUS(HPV)INTHENORMALANDABNORMALCERVICALSAMPLESZhangWei;张伟;JinShunqia...  相似文献   
997.
1982年3月~1994年12月,我们为各类肺部疾病进行肺切除术106例。术中、术后发生并发症23例次占21.6%,术后30日内死亡2例占1.8%.文内着重对支气管胸膜瘘、血胸、肺血管损伤大出血、癌栓脱入对侧肺支气管、肺静脉癌栓脱入股动脉及心跳聚停等并发症的防治及紧急处理进行了讨论。此外,作者认为,肺叶切除术目前在大多数病例仍是肺癌外科的“标准术式”,但在心肺功能允许并由于技术或肿瘤学原因非行全肺切除术才能达到根治性切除时,就要果断地行全肺切除,心包外处理肺血管有困难时,要毫不迟疑地采取心包内途径。  相似文献   
998.
目的 探讨上海市≥50岁人群维生素D水平与握力的关系。方法 数据来源于WHO全球老龄化与成人健康研究我国上海市2018-2019年数据,采用logistic回归模型分析维生素D水平与握力的关系,进一步按照性别、年龄及乳制品摄入情况进行分层;采用限制性立方样条曲线绘制维生素D水平与低握力的剂量-反应曲线。结果 共4 391人纳入研究,其中男性2 054人(46.8%);年龄(67.02±8.81)岁;低握力1 421人(32.4%);维生素D不足及缺乏分别为1 533人(34.9%)和401人(9.1%)。在调整相关混杂因素后,logistic回归分析结果显示,维生素D缺乏的人群发生低握力的风险更高(OR=1.41,95%CI:1.09~1.83);在男性中,调整相关混杂因素后,维生素D缺乏与低握力发生风险呈显著正相关(OR=1.67,95%CI:1.12~2.50),而女性中两者之间无关联(OR=1.30,95%CI:0.97~1.74);在60~69岁及≥80岁年龄组中,调整相关混杂因素后,维生素D缺乏与低握力发生风险呈显著正相关(OR=1.57,95%CI:1.05~2.35;OR=2.40,95%CI:1.08~5.31),在乳制品摄入<250 ml/d的人群中,调整相关混杂因素后,二者之间呈显著正相关(OR=1.57,95%CI:1.17~2.09),而在乳制品摄入≥250 ml/d的人群中无明显关联。限制性立方条样图显示,低握力的发生风险可能随维生素D含量的上升而降低,但差异无统计学意义(P>0.05)。结论 维生素D水平与握力存在一定的关系,维生素D缺乏人群出现低握力的风险更高。  相似文献   
999.
目的:探讨高熔铸件浇铸不全的可能原因。方法:通过对临床85件可摘铸件缺损的初浅分析,总结出浇铸不全的可能原因。结果:高熔铸件浇铸不全的原因有以下7个方面:①铸金量不足;②熔金温度过低;③离心力不够;④铸道布局不当;⑤铸件过薄;⑥高温包埋料透气性差;⑦铸圈温度下降。结论:通过查找原因,总结出预防的方法,对提高高熔铸件修复体的质量有一定的作用。  相似文献   
1000.
高校离退休老人躯体健康与心理状况的相关性研究   总被引:10,自引:1,他引:9  
目的:了解离退休老人躯体健康和心理状况的关系。方法:采用CMI和SCL-90对225名高校离退休老人进行调查,分析两者的关系。结果:既往健康状况、神经系统疾病和躯体化成正相关;强迫与呼吸系统疾病成正相关,与心血管系统疾病成负相关;疲劳感和敌对成负相关,和睡眠饮食障碍成负相关。结论:维持老人心身健康,主要在于防治慢性疾病和神经系统疾病,以及对躯体化障碍和强迫症状的干预  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