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   662篇
  免费   58篇
  国内免费   1篇
耳鼻咽喉   4篇
儿科学   36篇
妇产科学   27篇
基础医学   90篇
口腔科学   31篇
临床医学   54篇
内科学   139篇
皮肤病学   14篇
神经病学   41篇
特种医学   13篇
外科学   57篇
综合类   13篇
一般理论   1篇
预防医学   89篇
眼科学   23篇
药学   36篇
中国医学   4篇
肿瘤学   49篇
  2023年   13篇
  2022年   12篇
  2021年   44篇
  2020年   14篇
  2019年   28篇
  2018年   22篇
  2017年   25篇
  2016年   27篇
  2015年   27篇
  2014年   43篇
  2013年   45篇
  2012年   56篇
  2011年   53篇
  2010年   32篇
  2009年   21篇
  2008年   40篇
  2007年   34篇
  2006年   22篇
  2005年   41篇
  2004年   36篇
  2003年   30篇
  2002年   23篇
  2001年   7篇
  2000年   3篇
  1999年   3篇
  1998年   4篇
  1997年   2篇
  1996年   2篇
  1994年   1篇
  1993年   3篇
  1992年   2篇
  1991年   1篇
  1990年   2篇
  1988年   1篇
  1981年   1篇
  1976年   1篇
排序方式: 共有721条查询结果,搜索用时 0 毫秒
671.
672.
673.
674.
Aim  To analyse volumetrically using spiral computed tomography (SCT) the efficacy of various techniques to fill root canals.
Methodology  Root canals in 40 maxillary central incisors were instrumented with K-files to size 60 and the volume of the canal measured using SCT. The teeth were divided into four groups of 10 each and root filled by lateral compaction, Thermafil, Obtura II and System B techniques, respectively. AH plus was used as sealer with all techniques. The filled volume in each canal was measured using SCT and the percentage of obturated volume (POV) was calculated. The data were statistically analysed using Kruskal–Wallis test and Mann–Whitney U -test.
Results  The four groups were comparable in canal volume. The overall POV was 80.4%, 93.3%, 84.8% and 93.7% for lateral compaction, Thermafil, Obtura II and System B, respectively ( P  < 0.05).
Conclusion  The greatest POV was obtained with System B and Thermafil. Voids were seen in all root fillings.  相似文献   
675.
Diverse proteins are known to be capable of forming amyloid aggregates, self-seeding fibrillar assemblies that may be biologically functional or pathological. Well-known examples include neurodegenerative disease-associated proteins that misfold as amyloid, fungal prion proteins that can transition to a self-propagating amyloid form and certain bacterial proteins that fold as amyloid at the cell surface and promote biofilm formation. To further explore the diversity of amyloidogenic proteins, generally applicable methods for identifying them are critical. Here we describe a cell-based method for generating amyloid aggregates that relies on the natural ability of Escherichia coli cells to elaborate amyloid fibrils at the cell surface. We use several different yeast prion proteins and the human huntingtin protein to show that protein secretion via this specialized export pathway promotes acquisition of the amyloid fold specifically for proteins that have an inherent amyloid-forming propensity. Furthermore, our findings establish the potential of this E. coli-based system to facilitate the implementation of high-throughput screens for identifying amyloidogenic proteins and modulators of amyloid aggregation.  相似文献   
676.
Respiratory syncytial virus (RSV) causes significant infant mortality worldwide and a vaccine may be available soon. This study determined age-stratified anti-RSV antibody positivity (enzyme-linked immunosorbent assay [ELISA]) at Pune, India (cord blood-85 years). Antibody positivity declined from 100% at birth to 71.3% (3 months), and 0.7% (6 months). A significant rise was noted at 15 months (16%), 16 to 24 months (64.5%) and 4 years (95.2%) with concomitant IgM-anti-RSV positivity indicative of recent infection. Antibody decline was higher in infants born preterm than full-term. Across subsequent age groups including the elderly, antibody positivity was similar and comparable, suggestive of repeated exposure to the virus. Early protection/vaccination is essential for the infant population.  相似文献   
677.
Chronic pain is multi-dimensional. At the physical level itself, beyond the nociceptive pathway, there is hyper arousal state of the components of the nervous system, which negatively influences tension component of the muscles, patterns of breathing, energy levels and mindset, all of which exacerbate the distress and affect the quality of life of the individual and family. Beginning with the physical body, Yoga eventually influences all aspects of the person: vital, mental, emotional, intellectual and spiritual. It offers various levels and approaches to relax, energize, remodel and strengthen body and psyche. The asanas and pranayama harmonize the physiological system and initiate a “relaxation response” in the neuro endocrinal system. This consists of decreased metabolism, quieter breathing, stable blood pressure, reduced muscle tension, lower heart rate and slow brain wave pattern. As the neural discharge pattern gets modulated, hyper arousal of the nervous system and the static load on postural muscle come down. The function of viscera improves with the sense of relaxation and sleep gets deeper and sustained; fatigue diminishes. Several subtle level notional corrections can happen in case the subject meditates and that changes the context of the disease, pain and the meaning of life. Meditation and pranayama, along with relaxing asanas, can help individuals deal with the emotional aspects of chronic pain, reduce anxiety and depression effectively and improve the quality of life perceived.  相似文献   
678.
The objective of this study was to find a pattern in vocalizations of children with Autism Spectrum Disorder (ASD). We compared the intonational features of 15 children with ASD who showed speech, aged 4–10 years, with 10 age-matched typically developing controls. Exaggerated pitch, pitch range, pitch excursion and pitch contours were observed in speech of children with autism, but absent in age-matched controls. These exaggerated features, which are distinctive characteristics of motherese, were also seen in interactions of an independent group of 8 mothers of typical infants using child-directed speech. Our findings provide the first evidence of a distinct pattern in vocal output from children with autism. They also demonstrate that speech patterns might follow a delayed developmental trajectory in these children.  相似文献   
679.
Physical activity (PA) is a key management strategy for type 2 diabetes. Despite the known benefits, PA levels are low. Whether the low level of PA is related to lack of knowledge or support is not fully understood. This study was conducted to describe where and how often adults with type 2 diabetes receive and seek information related to PA and examine the relationships between the source and quality of PA information with PA behaviors. A series of questions related to the source and quality of PA information were added to a baseline survey distributed to the participants (N = 244) of the Canadian Aerobic and Resistance Training in Diabetes (CARED) study. Physicians and television were found to be the main sources of PA-related information. In our cross-sectional model, sources of PA-related information other than that from health care professionals explained 14% (p = .05) and 16% (p < .05) of the variance for aerobic-based and resistance training behaviors and 22% (p < .01) and 15% (p < .05) for these behaviors in our longitudinal model. Physical activity (PA)-related information is widely available to adults with type 2 diabetes. Neither the quantity nor the quality of the PA information provided by health care professionals predicted PA behavior. These data provide further insight into the modes with which PA can be promoted to adults with type 2 diabetes.  相似文献   
680.
Vanilla, being the world's most popular flavoring materials, finds extensive applications in food, beverages, perfumery and pharmaceutical industry. With the high demand and limited supply of vanilla pods and the continuing increase in their cost, numerous efforts of blending and adulteration in natural vanilla extracts have been reported. Thus, to ensure the quality of vanilla extracts and vanilla-containing products, it is important to develop techniques to verify their authenticity. Quantitatively, vanillin is the major compound present in the vanilla pods and the determination of vanillin is a vital consideration in natural vanilla extracts. This paper provides a comprehensive account of different extraction processes and chromatographic techniques applied for the separation, identification and determination of chemical constituents of vanilla. The review also provides an account of different methods applied for the quantification and the authentification of chemical constituents of vanilla extract. As the various properties of vanilla are attributed to its main constituent vanillin, its physico-chemical and bioactive properties have also been outlined.  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