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   182369篇
  免费   16026篇
  国内免费   11731篇
耳鼻咽喉   1567篇
儿科学   1807篇
妇产科学   2428篇
基础医学   21884篇
口腔科学   3003篇
临床医学   25345篇
内科学   26942篇
皮肤病学   1830篇
神经病学   10256篇
特种医学   6675篇
外国民族医学   109篇
外科学   18022篇
综合类   28810篇
现状与发展   42篇
一般理论   12篇
预防医学   10665篇
眼科学   5492篇
药学   18483篇
  203篇
中国医学   10228篇
肿瘤学   16323篇
  2025年   51篇
  2024年   2505篇
  2023年   3791篇
  2022年   7710篇
  2021年   9484篇
  2020年   7509篇
  2019年   6510篇
  2018年   6469篇
  2017年   5745篇
  2016年   5438篇
  2015年   8310篇
  2014年   10088篇
  2013年   8619篇
  2012年   12912篇
  2011年   14429篇
  2010年   8520篇
  2009年   6540篇
  2008年   8940篇
  2007年   8909篇
  2006年   9075篇
  2005年   9073篇
  2004年   5582篇
  2003年   5312篇
  2002年   4367篇
  2001年   3915篇
  2000年   4275篇
  1999年   4552篇
  1998年   2817篇
  1997年   2822篇
  1996年   2251篇
  1995年   2100篇
  1994年   1737篇
  1993年   1121篇
  1992年   1517篇
  1991年   1289篇
  1990年   1035篇
  1989年   883篇
  1988年   808篇
  1987年   717篇
  1986年   588篇
  1985年   420篇
  1984年   274篇
  1983年   196篇
  1982年   117篇
  1981年   113篇
  1980年   87篇
  1979年   111篇
  1978年   42篇
  1975年   48篇
  1974年   41篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
冠状切口在颧骨复合体骨折中的应用   总被引:6,自引:0,他引:6  
目的探讨颧骨复合体骨折复位和固定术中应用冠状切口入路的手术适应证、手术方法及减少并发症的措施。方法84例颧骨复合体骨折的患者应用单纯冠状切口为36.9%、冠状切口 下睑缘切口为32.1%、冠状切口 下睑缘切口 前庭沟切口为16.7%和冠状切口 前庭沟切口为14.3%。术中患者均使用微型钛板或小型钛板坚强内固定。对于眶底骨折出现眼球内陷的患者以羟基磷灰石人工骨进行眶底重建。结果84例患者均未发生手术后切口感染,术后随访3个月到2年,无面神经永久性损伤,术后所有咬合关系紊乱的患者均达到功能性咬合。通过训练后张口度得到满意恢复。8例患者术后患侧颧弓处仍稍显膨隆。术后眼球内陷只有1例仍大于3mm,其余均恢复满意。结论颧骨复合体骨折使用头皮冠状切口时,熟练掌握颞部的解剖层次是至关重要的,仔细保护神经及血管结构可减少手术并发症。  相似文献   
92.
BACKGROUND AND OBJECTIVE: Bone morphogenic proteins are known, in animal models, to promote many developmental processes, including osteogenesis. Clinical trials are currently underway to evaluate the potential of bone morphogenic proteins to promote bone and periodontal regeneration in humans. The aim of this study was to establish an optimal cell culture condition for using to study the biological effects of recombinant human bone morphogenic protein-2 on periodontal ligament cells. MATERIAL AND METHODS: The roles of serum concentration, types of culture medium (alpha-modified essential medium or Dulbecco's modified Eagle's medium), the presence of osteoinductive medium (including dexamethasone, ascorbic acid and beta-glycerophosphate), and timing of addition of the osteoinductive medium and recombinant human bone morphogenic protein-2, on the expression of alkaline phosphatase were investigated in cultured periodontal ligament cells. Cytochemical stainings and biological assay of alkaline phosphatase were also demonstrated. RESULTS: Our results suggested that an increased concentration of serum might mask the effect of recombinant human bone morphogenic protein-2 on the expression of alkaline phosphatase in periodontal ligament cells. alpha-Modified essential medium was found to induce a stronger cytochemical staining of the alkaline phosphatase than Dulbecco's modified Eagle's medium under similar culture conditions. Pre-incubation of cells with osteoinductive medium before the addition of various concentrations of recombinant human bone morphogenic protein-2 enhanced greater alkaline phosphatase expression than the simultaneous presence of both osteoinductive medium and recombinant human bone morphogenic protein-2. CONCLUSION: The findings of this study suggest that the effect of recombinant human bone morphogenic protein-2 on periodontal ligament cells could be efficiently investigated after the proper selection of culture variables and temporal sequence of adding bioactive factors. The optimal culture condition identified in this study might be useful in further studies to elucidate the regulatory mechanism of periodontal ligament cells in periodontal regeneration after stimulation with recombinant human bone morphogenic protein-2.  相似文献   
93.
1354 freshmen have been investigated to discover the relationship between dental diseases and environments,living habits and personal sanitary conditions,because urban young men like sweet foods and snacks,the incidence of caries is greater in the cities than in the country,more people with tetracycline discolored tooth live in urban areas than in the rustic ones,which is due to dense living conditions, vulnerable to respiratory organs disease,medical conditions and convenience of taking tetracycline when ill;on the other hand,gingivitis is more common within the country students than within the city students,for those students from the country are used to brush their tooth after adolescence and usually have more dental calculus which is harmful to the gingiva.More than half of the investigated freshmen are ignorant of correct method of brushing and oral health and that is important factors of high rate of dental disease,according to the above reasons,the effective measures should educated to prevent dental disease.  相似文献   
94.
目的 探讨雷帕霉素(rapamycin)与顺铂(cisplatin)联合使用对趋化因子CCL19调节头颈鳞状细胞癌细胞活性的影响.方法 应用甲基噻唑基四唑(MTT)法及流式细胞仪检测顺铂及雷帕霉素对CCL19诱导后人头颈鳞状细胞癌淋巴结转移细胞系(PCI-4B、PCI-37B)生长抑制作用、细胞凋亡作用和细胞周期变化.使用Calcusyn软件计算两种药物(浓度比为80:1)联合使用时的剂量效应参数及联合指数(combination index,CI),使用SPSS 11.0软件包进行统计分析.结果 顺铂及雷帕霉素可以分别提高CCL19作用后细胞的生长抑制率(CCL19+顺铂作用后两细胞系的生长抑制率为21.22%±2.68%和22.76%±2.79%,CCL19+雷帕霉素作用后为19.46%±2.54%和20.6%±4.38%)、细胞G1期比例(CCL19+顺铂作用后两细胞系的G1期比例为72.14%±2.66%和76.39%±1.45%,CCL19+雷帕霉素作用后为75.26%±5.92%和74.00%±1.51%)和凋亡率(CCL19+顺铂作用后两细胞系的凋亡率9.59%±0.86%和7.55%±0.66%,CCL19+雷帕霉素作用后为8.21±1.80%和6.26±0.78%).两种药物浓度比为80:1联合使用时,PCI-4B细胞在半数抑制量(inhibitory concentration 50%,IC50)以下,CI<1,IC75以上CI>1;PCI-37B则在IC75以下CI<1,IC90以上CI>1.结论 顺铂及雷帕霉素均有抑制CCL19对人头颈鳞状细胞癌淋巴结转移细胞的活性调节作用,并且二者联合使用存在协同作用.
Abstract:
Objective To investigate the synergistic effects of rapamycin and cisplatin on head and neck squamous cancer cells regulated by chemokine( C-C motif) ligand 19 (CCL19). Methods The role of rapamycin and cisplatin was detected on cell-cycle and apoptosis in CCL19 induced PCI-4B and PCI-37B cells by methyl thiazolyl tetrazolium (MTT) and flow cytometry(FCM). Dose-effect relationship parameters and combination index(CI) were calculated on the median-effect equation and multiple drug effect equation using computer software CalcuSyn. Statistical analysis was performed by the unpaired student's t-test.Results Rapamycin and cisplatin could respectively increase the growth arrest, the proportion of G1 phase and apoptosis of CCL19 induced cancer cells (P <0. 05 ). Under inhibitory concentration 50% (IC50), CI was less than 1, and in IC75, it was more than 1 in PCI-4B cells. In PCI-37B cells, under IC75, CI was less than 1, and in IC90, it was more than 1. Conclusions Rapamycin and cisplatin can inhibit CCL19-regulated PCI-4B and PCI-37B cells' survival. The two drugs have synergistic effects when used in combination.  相似文献   
95.
目的 分析颌面部巨大血管畸形的临床特点及治疗方法,探讨放疗在血管畸形治疗中的可行性.方法 回顾分析2000年1月至2008年1月浙江大学医学院附属第二医院施行三维立体定向适形放射治疗的颌面部巨大血管畸形6例的临床资料,并主要根据影像检查与临床体检结果判断疗效.结果 6例患者在术中、术后无严重并发症,均对治疗后面部外形满意,MRI示病变范围缩小,甚至消失.随访0.5~9年,6例患者均无明显复发迹象.无一例出现视器损伤、张口受限等放疗并发症.结论 三维立体定向适形放疗可以作为一种安全有效治疗颌面部巨大血管畸形的方法.
Abstract:
Objective To discuss the clinical use of radiotherapy in the treatment of giant vascular malformation. Methods Six patients with giant vascular malformation in oral and maxillofacial region were treated by three dimensional radiation therapy in Department of Stomatology, The Second Affiliated Hospital,School of Medicne, Zhejiang University in the last ten years and the cilinical data were reviewed. The treatment results were evaluated by clinical examination and radiology. Results No complication was observed during and after the radiotherapy. All patients were satisfied with the aesthetic results. The lesions in MRI were all reduced and even disappeared. There was no sign of recurrence during the follow-up period.Conclusions Three dimensional radiotherapy is safe and effective for oral and maxillofical vascular malformation.  相似文献   
96.
目的探讨粘接式全牙列矫治器联合面具前牵治疗乳牙早期反  相似文献   
97.
类探讨增进牙龈上皮细胞在钛表面附着的因素,将基底膜提物Matrigel涂在光滑纯钛片表面,扫描电镜观察原代培养的人牙龈上皮细胞在涂Matrigel 钛表面和光滑钛表面的伸展情况。  相似文献   
98.
Aim  To evaluate human pulp tissue response following direct pulp capping with a self-etching adhesive: Clearfil SE BOND (SB).
Methodology  Forty-five sound teeth from 20 subjects were used. Forty-one teeth had their pulp mechanically exposed at the base of a Class 1 cavity preparation and were divided into two groups: group 1, teeth were capped with SB ( n  = 21), and group 2, with calcium hydroxide cement (CH) ( n  = 20). Four teeth were maintained intact as an untreated control group. After 7, 30 and 90 days, respectively, 15 teeth were extracted and processed for light microscopic examination. Pulp healing and bacterial microleakage were assessed by haematoxylin and eosin, Masson trichrome and Brown and Brenn stain techniques. The data were analysed statistically by using the Mann–Whitney U test.
Results  After the 7-day observation period, the inflammatory reaction in the SB group was slight and significantly less severe than that of the CH group ( P  < 0.05). After the 30- and 90-day observation periods, the inflammatory reaction was slight in both groups, but specimens with dentine bridge formation in the SB group were significantly less common than those in the CH group ( P  < 0.05).
Conclusions  Clearfil SB had good biocompatibility with human pulp tissue, but its ability to induce reparative dentine was significantly lower than that of calcium hydroxide.  相似文献   
99.
Oral Radiology - To evaluate the feasibility, safety, and efficacy of endovascular interventions in the emergent management of life-threatening hemorrhage associated with head and neck neoplasm....  相似文献   
100.
镧、铈、氟在抑制人离体牙根面脱矿中作用的比较研究   总被引:5,自引:0,他引:5  
作者采用含镧(La)、铈(Ce)、氟(F)的脱矿液,在体外模拟口腔pH循环变化的环境中对离体人牙根面进行抑制脱钙的实验研究,并采用化学及能谱分析手段,对La,Ce,F在根面的抑制脱钙作用进行定量分析。结果显示,这三种微量元素对根面均有明显的抑制脱钙作用,但F较La、Ce的抑制作用强.该研究还从晶体物理化学角度对La、Ce、F的抑制脱矿作用的机理进行探讨。  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