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   1332篇
  免费   111篇
  国内免费   69篇
  2024年   4篇
  2023年   43篇
  2022年   58篇
  2021年   93篇
  2020年   77篇
  2019年   92篇
  2018年   77篇
  2017年   66篇
  2016年   77篇
  2015年   81篇
  2014年   104篇
  2013年   152篇
  2012年   62篇
  2011年   84篇
  2010年   53篇
  2009年   41篇
  2008年   29篇
  2007年   49篇
  2006年   39篇
  2005年   35篇
  2004年   21篇
  2003年   24篇
  2002年   18篇
  2001年   26篇
  2000年   17篇
  1999年   10篇
  1998年   7篇
  1997年   11篇
  1996年   9篇
  1995年   10篇
  1994年   5篇
  1993年   6篇
  1992年   1篇
  1991年   6篇
  1990年   1篇
  1989年   5篇
  1988年   6篇
  1986年   1篇
  1985年   5篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1980年   1篇
  1976年   1篇
  1975年   1篇
排序方式: 共有1512条查询结果,搜索用时 15 毫秒
191.
Pharmacokinetic studies play an important role in all stages of drug discovery and development. Recent advancements in the tools for discovery and optimization of therapeutic proteins have created an abundance of candidates that may fulfill target product profile criteria. Implementing a set of in silico, small scale in vitro and in vivo tools can help to identify a clinical lead molecule with promising properties at the early stages of drug discovery, thus reducing the labor and cost in advancing multiple candidates toward clinical development. In this review, we describe tools that should be considered during drug discovery, and discuss approaches that could be included in the pharmacokinetic screening part of the lead candidate generation process to de-risk unexpected pharmacokinetic behaviors of Fc-based therapeutic proteins, with an emphasis on monoclonal antibodies.  相似文献   
192.
There is an alleged tension between undue inducement and exploitation in research trials. This paper considers claims that increasing the benefits to research subjects enrolled in international, externally‐sponsored clinical trials should be avoided on the grounds that it may result in the undue inducement of research subjects. It proceeds from the premise that there are good grounds for thinking that, at least some, international research sponsors exploit trial participants because they do not provide the research population with a fair share of the benefits of research. This provides a prima facie argument for increasing the benefits for research participants. Concern over undue inducement is a legitimate moral concern; however, if this concern is to prevent research populations from receiving their fair share of benefits from research there must be sufficient evidence that these benefits will unduly influence patients’ decision‐making regarding trial participation. This article contributes to the debate about exploitation versus undue inducement by introducing an analysis of the available empirical research into research participants’ motivations and the influence of payments on research subjects’ behaviour and risk assessment. Admittedly, the available research in this field is limited, but the research that has been conducted suggests that financial rewards do not distort research subjects’ behaviour or blind them to the risks involved with research. Therefore, I conclude that research sponsors should prioritise the prevention of exploitation in international research by providing greater benefits to research participants.  相似文献   
193.
Objective: To assess the effect of baseline serum calcium on the progression of periodontal disease in non‐institutionalized elderly. Background: Although a few studies have found some evidence of the role played by dietary calcium in periodontal disease process, there is a paucity of information pertinent to longitudinal assessment of serum calcium‐periodontal relationships. Material and methods: Clinical attachment levels of 266 Japanese subjects aged 70 years were recorded at baseline and annually for six consecutive years. Progression of periodontal disease (PPD) was defined as the number of teeth that showed additional attachment loss of ≥3 mm during the 6 years. The number of PPD was calculated for each subject and categorised into four levels, namely, PPD0, PPD1, PPD2 and PPD3 where the number of teeth with additional attachment loss ranged from 0, 1–10, 11–20 and >20 respectively. The levels of serum calcium, albumin, random blood sugar, immunoglobulin (IgG, IgA and IgM), gender, smoking habits, education, gingival bleeding and the number of teeth present were obtained at baseline. Results: Serum calcium, IgA, smoking, gingival bleeding and teeth present were associated with PPD at p ≤ 0.10 and were included in a multinomial logistic regression analysis. Serum calcium was the only variable that was significantly associated with PPD with relative risks of 100 at PPD1 and PPD2, respectively, and 1000 at PPD3. Conclusion: Serum calcium may be considered a risk factor for periodontal disease progression in non‐institutionalized elderly.  相似文献   
194.
195.
Background: Studies show that elders wearing implant overdentures have improved nutrition and quality of life. However, upfront costs of this therapy are high, and the income of elderly edentulous populations is low. Objectives: This study was designed (i) to measure the preferences of edentulous patients for mandibular two‐implant overdentures using Willingness‐To‐Pay (WTP) and Willingness‐To‐Accept (WTA), (ii) to assess the effect of long‐term financing on WTP and (iii) to assess the desired role of health care plans in financing dental prostheses. Methods: Edentulous elders (68–79 years; n = 36) wearing maxillary dentures and either a mandibular conventional denture (CD, n = 13) or a two‐implant overdenture with ball attachments (IOD, n = 23) participated in this study. All had received their prostheses 2 years previously, as part of a randomised clinical trial. A three‐part questionnaire was completed during a 20‐min interview with a trained researcher. Results: Forty‐six per cent (6/13) of the CD wearers and 70% (16/23) of the IOD wearers were willing to pay three times more than the current cost of conventional dentures for implant prostheses. These percentages were increased to 77% (CD) and 96% (IOD) if participants could pay for implant overdentures in monthly instalments. Eighty‐six per cent (31/36) of all participants in both groups (21/23 IOD; 10/13 CD) thought that the government should cover at least some of the cost of implant overdentures. Conclusions: This study shows that, the majority of elderly edentate individuals who have not experienced mandibular two‐implant overdenture therapy are willing to pay the cost, particularly when payment can be made in monthly instalments.  相似文献   
196.
The current paper presents the second part of chapter 6 of the second edition of the European Guidelines for Quality Assurance in Cervical Cancer Screening . The first part of the same chapter was published in a previous issue ( Cytopathology 2008;19:342–54). This part provides guidance on how to manage and treat women with histologically confirmed cervical intraepithelial neoplasia. The paper describes the characteristics, indications and possible complications of excisional and ablative treatment methods. The three options to monitor the outcome after treatment (repeat cytology, HPV testing and colposcopy) are discussed. Specific recommendations for particular clinical situations are provided: pregnancy, immuno-suppression, HIV infection, post-menopause, adolescence and cyto-colpo-histological disparity. The paper ends with recommendations for quality assurance in patient management and some general advice on how to communicate screening, diagnosis and treatment results to the woman concerned. Finally, a data collection form is attached.  相似文献   
197.
The genetic structure of a global sample of 170 clinical and nonclinical Saccharomyces cerevisiae isolates was analysed using 12 microsatellite markers. High levels of genetic diversity were revealed both among the clinical and among the nonclinical S. cerevisiae isolates without significant differentiation between these two groups of isolates, rendering a single origin of pathogenic isolates unlikely. This suggests that S. cerevisiae is a true opportunistic pathogen, with a diversity of unrelated genetic backgrounds able to cause infections in humans, and that the ability of S. cerevisiae isolates to cause infections is likely due to a combination of their phenotypic plasticity and the immune system status of the exposed individuals. As was previously reported for bread, beer and wine strains and for environmental S. cerevisiae isolates, the microsatellite genotypes indicated ploidy level variation, from possibly haploid up to tetraploid, among clinical S. cerevisiae isolates. However, rather than haploid, sporulation proficiency and spore viability data indicated that most S. cerevisiae isolates that were mono-allelic at all examined microsatellite loci were likely homothallic and self-diploidized. Interestingly, the proportion of heterozygous clinical isolates was found to be significantly higher than the proportion of heterozygous nonclinical isolates, suggesting a selective advantage of heterozygous S. cerevisiae yeasts in clinical environments.  相似文献   
198.
Background: We clarified the clinical significance of measurement of IgG antibody titers against Helicobacter pylori using data from a nested case–control study from a large-scale cohort study in Japan.
Method: Participants included 36,745 subjects from the Japan Health Center-based Prospective Study who responded to the baseline questionnaire and provided a blood sample. Subjects were aged 40–69 years and were followed over 15 years after initial sampling. Controls were matched to 511 gastric cancer patients. Plasma surface antigen (Hp)-IgG titer was measured using ELISA, and mucosal atrophy was determined by measuring pepsinogen I and II levels.
Results: Seropositive subjects with low Hp-IgG titer and mucosal atrophy showed a higher risk for gastric cancer than high-titer subjects. Odds ratio (OR) referred to cases with true negative IgG titers and no mucosal atrophy. In moderately atrophic subjects, the low titer OR was 19.0, with a 95% confidence interval (CI) of 7.7–46.9, and 12.5 for high titer, with a 95% CI of 5.2–30.0. In severely atrophic subjects, the low titer OR was almost double that of high-titer subjects (OR = 30.2, 95% CI = 12.4–73.7 and OR = 15.9, 95% CI = 6.3–40.3, respectively). These associations were observed more frequently for differentiated than undifferentiated gastric cancer.
Conclusion: Combination assay with Hp-IgG titer and pepsinogens may help identify groups at high risk for gastric cancer. Subjects with low Hp-IgG titer and mucosal atrophy were at extremely high risk for gastric cancer, particularly differentiated cancer. Subjects with this background may require ongoing observation and periodic endoscopic examination for early cancer detection.  相似文献   
199.
周亚芳  易继平  江泓 《生物磁学》2009,(13):2492-2494,F0002
目的:探讨鼻咽癌放疗后致迟发性放射性脑病的临床特征。方法:对中南大学湘雅医院神经内科所收治的34例鼻咽癌放疗后致迟发性放射性脑病患者临床资料、治疗方法及预后进行回顾性研究。结果:34例迟发性放射性脑病患者的临床特征包括头痛、头晕、记忆力下降、精神异常、抽搐、复视、面瘫或面部麻木、听力下降、言语增多、肢体无力、走路不稳、肢端麻木等。头部MRIT1WI呈低信号,T2WI呈高信号,增强后呈不规则强化。34例均随访,其中死亡11例,占32.35%;现存活23例,17例伴有严重症状,生存质量差,占50%。结论:鼻咽癌放疗后致迟发性放射性脑病临床表现各异,患者预后较差,临床上需尽早诊断,积极治疗,定期随诊。  相似文献   
200.
目的报道1例铁锈色小孢子菌感染引起的结节性肉芽肿及病理改变,探讨诊断和治疗。方法反复取感染部位分泌物进行细菌和真菌培养,对皮损进行病理检查,将培养菌落进行rDNAITS测序鉴定。结果分泌物PDA培养基中可见灰色菌落,表面呈绒毛状,37℃生长良好,镜下可见分隔菌丝未见分生孢子。分子生物学ITS测序结果显示:病原菌与铁锈色小孢子菌相似率为100%。确诊后用伊曲康唑治疗取得良好效果。结论在新疆特别是南疆地区头癣是很常见的皮肤病。对皮肤出现结节性损害且长期抗炎治疗不愈的患者,要考虑真菌感染的可能,及时诊断并早期进行抗真菌治疗。  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