全文获取类型
收费全文 | 44975篇 |
免费 | 4012篇 |
国内免费 | 1493篇 |
专业分类
耳鼻咽喉 | 442篇 |
儿科学 | 865篇 |
妇产科学 | 466篇 |
基础医学 | 3138篇 |
口腔科学 | 7069篇 |
临床医学 | 4892篇 |
内科学 | 6944篇 |
皮肤病学 | 1179篇 |
神经病学 | 1692篇 |
特种医学 | 1748篇 |
外科学 | 2759篇 |
综合类 | 7181篇 |
现状与发展 | 11篇 |
一般理论 | 4篇 |
预防医学 | 5682篇 |
眼科学 | 939篇 |
药学 | 2835篇 |
37篇 | |
中国医学 | 2039篇 |
肿瘤学 | 558篇 |
出版年
2024年 | 713篇 |
2023年 | 1067篇 |
2022年 | 1907篇 |
2021年 | 2251篇 |
2020年 | 2233篇 |
2019年 | 1658篇 |
2018年 | 1558篇 |
2017年 | 1542篇 |
2016年 | 1752篇 |
2015年 | 1542篇 |
2014年 | 2904篇 |
2013年 | 3096篇 |
2012年 | 2659篇 |
2011年 | 2841篇 |
2010年 | 2281篇 |
2009年 | 2173篇 |
2008年 | 2091篇 |
2007年 | 2078篇 |
2006年 | 1752篇 |
2005年 | 1671篇 |
2004年 | 1307篇 |
2003年 | 1212篇 |
2002年 | 1013篇 |
2001年 | 965篇 |
2000年 | 764篇 |
1999年 | 570篇 |
1998年 | 595篇 |
1997年 | 498篇 |
1996年 | 400篇 |
1995年 | 436篇 |
1994年 | 365篇 |
1993年 | 270篇 |
1992年 | 349篇 |
1991年 | 284篇 |
1990年 | 220篇 |
1989年 | 219篇 |
1988年 | 205篇 |
1987年 | 174篇 |
1986年 | 159篇 |
1985年 | 123篇 |
1984年 | 100篇 |
1983年 | 75篇 |
1982年 | 64篇 |
1981年 | 45篇 |
1980年 | 46篇 |
1979年 | 43篇 |
1978年 | 34篇 |
1977年 | 39篇 |
1976年 | 31篇 |
1975年 | 36篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Unsal E Paksoy C Soykan E Elhan AH Sahin M 《Community dentistry and oral epidemiology》2001,29(4):272-277
OBJECTIVE: Besides genetic factors, tobacco smoking has been found to be the major cause of oral melanin pigmentation. The purpose of the present study was to evaluate the frequency of oral melanin pigmentation in a Turkish population and to present its correlation with clinical parameters relevant to periodontal status in current smokers, non-smokers, former smokers. METHOD: A sample of 496 patients was randomly selected. The subjects were interviewed regarding their smoking habits. They were clinically examined by a single examiner for the presence of oral melanin pigmentation in different oral mucosal regions. The same examiner recorded the clinical parameters including GI (gingival index), PI (plaque index), BOP (bleeding on probing), PD (probing depth) and GR (gingival recession). Examiner 2 completed a questionnaire concerning skin color and smoking habits. RESULTS: In the study group, 41% were current smokers, 46% nonsmokers and 13% former smokers. The frequencies of pigmented areas were significantly higher in current smokers than in those without any smoking habits. The clinical parameters revealed similar findings for all groups. Low GI and BOP values were observed for current smokers when compared with non-smokers and former smokers, respectively. GI values were significantly associated with the pigmentations in gingiva. CONCLUSIONS: The results of our study show that smokers in a Turkish population had significantly more pigmented oral surfaces than nonsmokers. 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.
Greenberg BL Glick M Goodchild J Duda PW Conte NR Conte M 《Journal of the American Dental Association (1939)》2007,138(6):798-804
BACKGROUND: The authors assessed the utilization of oral health care professionals (OHCPs) as a resource for identifying patients who were unaware of their increased risk of developing cardiovascular disease (CVD). METHODS: OHCPs administered a CVD risk-screening questionnaire, measured blood pressure and tested cholesterol levels, high-density lipoprotein levels and hemoglobin A1c (HgA1c) levels using "finger-stick" blood testing in 100 patients treated in a dental school clinic who were unaware of their CVD risk status. The authors determined the prevalence of specific risk factors (that is, smoking and abnormal levels of systolic blood pressure, lipids, body mass index and HgA1c) and calculated Framingham 10-year coronary heart disease (CHD) risk scores. RESULTS: Seventeen percent of the 100 patients (35 percent of men, 5 percent of women) had an increased global risk of experiencing a CHD event within 10 years (Framingham risk score>10 percent). Seventy-three percent of participants had one or more risk factors and 31 percent had two or more risk factors present. More men than women had low levels of high-density lipoprotein (45 percent [18/40] of men versus 3.3 percent [2/60] of women; P<.0001). The mean Framingham CHD risk score increased with increasing risk factor burden. CONCLUSIONS: OHCPs identified patients with an increased CHD risk who could benefit from primary prevention activities. A substantial proportion of study patients who were unaware of their risk status were at an increased risk of experiencing a CHD event within 10 years. OHCPs could contribute to public health CHD control efforts. 相似文献
94.
我国人口错畸形的发病率高达83.1%,随着人民生活水平和口腔保健意识的不断提高,正畸治疗需求量越来越大。口腔正畸固定矫治技术是矫治错畸形的主要方法,其在改善了错畸形患者美观和功能的同时,也对患 相似文献
95.
Effect of soaking in Hank's balanced salt solution or milk on PDL cell viability of dry stored human teeth 总被引:5,自引:0,他引:5
Abstract— This study was designed to evaluate the effect of soaking in either Hank's balanced salt solution (HBSS) or milk on peri− odontal ligament (PDL) cell viability in avulsed teeth. Dry storage times of 30, 60, and 90 min were evaluated. PDL cell viability was determined after removal of the cells from the root surfaces of extracted teeth using a modification of the procedure described by Nakashima (Arch Oral Biol 1991;36:655–63). After trypsinization and subsequent treatment in collagenase, the cells were stained with trypan blue, and viable and non-viable cells were counted using a hemocytometer and converted to percentages for statistical comparison. The results of this study demonstrated no significant difference in the number of viable cells with or without soaking in HBSS or milk at any of the dry storage times. In addition, there was no significant difference in PDL cell viability between the 30-and the 60-min dry periods. Although the soaking procedure had no obvious negative consequence, no simcant improvement in PDL cell viability by the addition of this step was demonstrated under the conditions of this study. 相似文献
96.
S. Takayama S. Murakami T. Nozaki K. Ikezawa Y. Miki T. Asano A. Terashima H. Okada 《Journal of periodontal research》1998,33(3):315-322
Basic fibroblast growth factor (FGF-2; bFGF) is a major mitogen for connective tissue cells, and participates in the healing process. It has already been reported that FGF-2 could be applicable to enhance periodontal regeneration. In the present study, we examined FGF receptor (FGFR) expression on human periodontal ligament (PDL) cells. The binding of [125I]-labeled FGF-2 to human PDL cells was studied by radioreceptor assay. The binding of [125I]-FGF-2 to PDL cells reached a plateau after 2.5 h incubation at 4°C and was inhibited by the addition of unlabeled FGF-2 and acidic FGF (FGF-1; aFGF), but not insulin-like growth factor-I, platelet-derived growth factor and transforming growth factor-β1. Scatchard analysis revealed the presence of approximately 1.0 × 105 FGF-2 binding sites per cell with an apparent Kd of 1.2 × 10-10 M. Interestingly, the binding of [125I]-FGF-2 on PDL cells reached its maximum at d 6 of the culture and then gradually decreased. Scatchard analysis also demonstrated that the number of FGFRs on a PDL cell was altered during the course of the culture, while the affinity between FGF-2 and its receptor was not. The responsiveness of PDL cells to FGF-2, which was monitored by the inhibitory effect on alkaline phosphatase activity, was reduced in proportion to the decrease in the number of FGFRs on the PDL cells. The present study suggests that PDL cells alter the responsiveness to FGF-2 during the course of the culture by changing the density of its receptor, and that the density of FGFR expression might be a marker of the cytodiflerentiation of PDL cells into mineralized tissue forming cells. 相似文献
97.
Min CK Wikesjö UM Park JC Chae GJ Pippig SD Bastone P Kim CS Kim CK 《Journal of clinical periodontology》2011,38(3):261-268
98.
G. R. Persson L. D. Engel B. J. Moncla R. C. Page 《Journal of periodontal research》1993,28(4):294-300
The non-human primate Macaca nemestrina was evaluated for use as a potential model in periodontal research by study of 16 animals. Using one incisor, premolar, and molar per quadrant, we measured supragingival plaque, severity of gingival inflammation, and pocket depth, and analyzed the subgingival flora. Serum IgG titers and avidities to antigens of Porphyromonas gingivalis (Pg) and Actinobacillus actinomycetemcomitans (Aa) were also assessed. Ten animals were between 13 and 24 years old, and six were between 4 and 5 years old. While mean gingival inflammation scores were significantly higher for older than for for younger animals (2.2 vs 1.8, p < 0.05), mean plaque index scores and mean probing depths did not differ significantly. The animals harbored a subgingival microflora considered to be pathogenic for humans including Aa, Pg, Bacteroides forsythus, Prevotella intermedia I and II, Campylobacter recta and Fusobacterium nucleatum . Aa, however, was found only in the younger animals. All of the animals had serum IgG antibodies reactive with antigens of Pg and Aa, and titers for Pg but not for Aa were significantly higher in the older relative to the younger animals (t test p < 0.02). In contrast, antibody avidity did not significantly differ between the two groups. A combined clinical assessment index based on maximum probing depth, gingival index score, and tooth loss was used to assess the overall disease severity. Titers were positively associated with disease severity (Spearman's rank correlation 0.57, p=0.02). We conclude that M. nemestrina harbors a subgingival microflora considered to be pathogenic for humans, manifest serum IgG antibodies to antigens of Pg and Aa, and exhibits clinical features of periodontitis comparable to those seen in humans. This species appears, therefore, to be a useful model for investigating periodontal microbial-host interactions, including the immune response. 相似文献
99.
目的:研究两种生长因子对牙周膜成纤维细胞在然金属表面附着和生长的影响。方法:将纯钛、钛75试件入在12孔培养板内,取生长良好的第五代人牙周膜成纤维细胞(PDLF)接种在试件表面,分别在接种后4h、12h、24h、72h进行贴壁细胞地数。结果:接种后4h、12h、24h、72h、bFGF组纯钛、钛75表面细胞附着数与空白对照组的差异均有显著性(P<0.05),rhBMP-2组纯钛、然75表面细胞附着数在初期(24h)与空白对组无显著性差异(P>0.05)。72h时与空白对照组差异有显著性(P<0.05),表明bFGF促进细胞附着和生长作用显著,而rhBMP-2促进细胞生长作用较促附着作用明显。结果:PDLF在钛金属表面的附着和生长可被生长因子所增强,但不同的生长因子对细胞附着和生长的生物学效应不尽相同。 相似文献
100.
The effect of three different periodontal pre-treatment procedures on the success of telescopic removable partial dentures 总被引:11,自引:0,他引:11
In this prospective study, 120 teeth consisting of maxillary and mandibular canines and premolars were divided into three groups each containing 40 teeth. The teeth were assigned randomly in quadrants to three different periodontal treatment protocols. The first group was treated with professional prophylaxis only. The second group received additional deep scaling. With the third group, additional surgical periodontal flap surgery and scaling was performed. Both papillary bleeding index (PBI) and probing depth (PD) were evaluated before, during and after treatment. During the subsequent prosthetic treatment phase all teeth were then used as telescope abutments supporting a removable prosthesis. The documentation of the attachment level (AL) was then used as a clinical parameter. One year after the incorporation of telescopic removable partial dentures (RPDs), PD, PBI and AL were again evaluated. The resulting periodontal parameters were compared between the different groups using the general linear model (GLM) repeated measures and the Kruskal-Wallis test for non-parametric variables. Differences within the three treatment groups were determined using the t-test, e.g. the Wilcoxon test for dependent variables (P < 0.05). A significant decrease in inflammatory indices (PBI) was found for all types of periodontal treatment (P < 0.03 for all groups). Additionally, the reduction in PD was significant for all of the three groups (P < 0.001 for all groups). The greatest reduction in PD was observed in the group in which a surgical approach was used. Evaluation of the attachment level after the incorporation of the telescopic RPDs showed that tooth position did not influence the periodontal prognosis and that the use of telescopic RPDs exerted no ascertainable negative influence on the periodontium of the abutment teeth. 相似文献