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   3693篇
  免费   190篇
  国内免费   41篇
耳鼻咽喉   61篇
儿科学   179篇
妇产科学   131篇
基础医学   315篇
口腔科学   188篇
临床医学   311篇
内科学   716篇
皮肤病学   102篇
神经病学   284篇
特种医学   115篇
外科学   658篇
综合类   37篇
一般理论   3篇
预防医学   328篇
眼科学   89篇
药学   211篇
中国医学   5篇
肿瘤学   191篇
  2023年   28篇
  2022年   65篇
  2021年   96篇
  2020年   60篇
  2019年   102篇
  2018年   113篇
  2017年   71篇
  2016年   117篇
  2015年   134篇
  2014年   163篇
  2013年   193篇
  2012年   275篇
  2011年   291篇
  2010年   171篇
  2009年   158篇
  2008年   294篇
  2007年   306篇
  2006年   228篇
  2005年   233篇
  2004年   221篇
  2003年   139篇
  2002年   142篇
  2001年   60篇
  2000年   42篇
  1999年   31篇
  1998年   15篇
  1997年   17篇
  1996年   11篇
  1995年   9篇
  1994年   8篇
  1993年   5篇
  1992年   14篇
  1991年   15篇
  1990年   10篇
  1989年   7篇
  1988年   6篇
  1987年   8篇
  1986年   8篇
  1985年   5篇
  1983年   8篇
  1979年   4篇
  1978年   2篇
  1977年   2篇
  1975年   4篇
  1974年   4篇
  1973年   2篇
  1972年   2篇
  1971年   11篇
  1969年   5篇
  1968年   2篇
排序方式: 共有3924条查询结果,搜索用时 10 毫秒
131.
Objective: To investigate the color alterations in enamel following the use of different orthodontic bonding resins and adhesive residue–removal burs.Materials and Methods:Metal brackets were bonded to extracted human premolars (n  =  175) by using an etch-and-rinse adhesive system, a self-etch adhesive system (SEP), or a resin-modified glass ionomer cement (RMGIC). After 24 hours of photoaging, the brackets were removed and the adhesive residue on the tooth surfaces was cleaned with either a tungsten carbide bur or a Stainbuster bur. Tooth colors were measured with a spectrophotometer at baseline, after adhesive removal, and after additional photoaging. Color evaluation was made, and color differences induced by photoaging were calculated. Statistical evaluation was made using the Kruskal-Wallis test and the Mann-Whitney U-test, with Bonferroni correction.Results:All specimens showed discoloration at varying levels. The highest color change was observed in the etch-and-rinse adhesive/tungsten carbide bur group. When the etch-and-rinse and self-etch adhesives were used, adhesive-remnant removal with Stainbuster burs resulted in significantly lower discoloration. The type of bur did not affect the extent of enamel discoloration in the RMGIC group.Conclusions:Orthodontic treatment alters the original color of enamel, and both the adhesive system and the resin-removal methods are responsible for this change. When brackets are bonded with the etch-and-rinse system or the SEP, cleaning the adhesive residuals with Stainbuster burs is recommended for minimal change. RMGIC can be safely cleaned with tungsten carbide burs.  相似文献   
132.
133.
BackgroundThere has been no valid and reliable Turkish scale that measures symptoms in children with eosinophilic esophagitis (EoE). The aim of the study is to test the validity and reliability of the Turkish version of Pediatric Eosinophilic Esophagitis Symptom Scores® (Tr-PEESS v2.0).Methods Relevant forms of Tr-PEESS v2.0 were applied to 2-18 years old children with EoE and to their parents. KINDL QoL patient and parent questionnaires and the GaziESAS scale developed in this study were used to test the convergent validity of Tr-PEESS v2.0. Discriminant validity was evaluated among 3 EoE treatment groups: under treatment, off treatment due to remission, and uncompliant with treatment. Reliability was evaluated by internal consistency, test–retest reliability, and item analysis.Results Fifty-two children/teens (mean age 130.2 ± 60.3 months) and 84 parents were interviewed twice one week apart. The mean duration of EoE was 47.2 ± 35.6 months. Tr-PEESS v2.0 reports correlated with GaziESAS (range 0.361-0.855) and KINDL QoL questionnaires (range −0.316 to 0.413). Parent report of Tr-PEESS v2.0 discriminated children uncompliant with treatment from the ones off treatment and undertreatment. Cronbach’s α values and intraclass correlation coefficients (ICC) values of Tr-PEESS v2.0 ranged from 0.614-0. 895 and 0.646-0.910, respectively.Conclusion Tr-PEESS v2.0 is a valid and reliable tool to use in Turkish children. GaziESAS is a new parent-proxy pediatric EoE scale with an additional adaptive behavior domain that passed scale developmental stages successfully for Turkish children with EoE.  相似文献   
134.
Rationale:Bacterial and fungal infections in Coronavirus Disease-19 (COVID-19) patients have been inadequately investigated and reported thus far. The safety profile of tocilizumab (TCZ) administration in candidemia patient still debatable.Patient concerns:A 54 year-old woman presenting with weakness on the left side of her body was diagnosed with COVID-19. After 7 days of admission, her condition worsened and developed respiratory distress and was having respiratory distress despite standard treatment.Diagnoses:Acute respiratory distress syndrome (ARDS) in COVID 19 was diagnoses based on real time-PCR swab, deterioration of PaO2/FiO2 and increased of acute phase reactants.Interventions:Anti Interleukin–6 (IL-6) was considered to tackle her inflammatory condition. Prior to TCZ administration, blood culture was performed and the result came with Candida tropicalis in the absence of bacterial growth.Outcomes:No major complications associated with intravenous antifungal or TCZ occurred. After 40 days of hospitalization, the patient''s clinical condition improved and was finally discharged.Lessons:This case underscores the safety profile of giving TCZ in candidemia as a secondary infection in severe COVID-19 patient.  相似文献   
135.
136.
This study reports the electropolymerization of novel keto functionalized octaethyl metal porphyrins (Zn2+ and Ni2+) in the presence of 4,4′-bipyridine (4,4′-bpy) as a bridging nucleophile. The polymer films were characterized by electrochemical, spectroscopic (UV-Vis, XPS, FT-IR and Raman spectroscopy) and imaging (AFM and SEM) techniques. The absorption and electronic spectra confirm the presence of both porphyrin and 4,4′-bipyridine units in the film. The surface morphology reveals homogeneous film deposition with average roughness values of approx. 8 nm. The theoretical studies performed offered insights into the interplay of different metal centres (Zn2+ and Ni2+) and the keto functionality of the porphyrin unit in the formation of copolymer films. The electrochemical interaction of polymer films with CO2 suggests a reversible trap and release of CO2 with low energy barriers for both the polymers.

Electropolymerization of keto functionalized porphyrins and 4,4′-bipyridine.  相似文献   
137.
As a typical transition metal dichalcogenide (TMD), molybdenum disulphide (MoS2) has become one of the most promising anode materials for lithium-ion batteries (LIBs) due to its desirable electrochemical properties. But the development of commercial MoS2 is limited by the problem of agglomeration. Thus, the production of MoS2 nanosheets with few (<10) layers is highly desired but remains a great challenge. In this work, a facile and scalable approach is developed to prepare large-flake, few-layer (4–8) MoS2 nanosheets with the assistance of ultrasonics. Simultaneously, the as-prepared MoS2 nanosheets and commercial bulk MoS2 were analysed under multiple spectroscopic techniques and a series of electrochemical tests to understand the dependence of electrochemical performance on structural properties. When used as anode materials for LIBs, the obtained MoS2 nanosheets provide a reversible capacity of 716 mA h g−1 at 100 mA g−1 after 285 cycles, and demonstrated an excellent capacity retention rate of up to 80%. Compared with that of commercial MoS2 (14.8%), the capacity retention rate of our MoS2 nanosheets has a significant improvement. This work explored the ability of few-layered MoS2 nanosheets in the field of LIBs while suggesting the commercialization of the MoS2 by an ultrasonicated ball milling exfoliation technique.

A facile and scalable approach is developed to prepare large-flake, few-layer (4–8) MoS2 nanosheets with the assistance of ultrasonics.  相似文献   
138.
139.
AimItching, a common skin disorder, impacts the quality of life of individuals. Itchy skin occurs more with increasing age and the prediction of itchy skin prognosis is necessary to provide good skincare. This study validated biomarkers in skin blotting to identify and measure itching sensation as well as conventional methods to measure skin barrier function.Materials and methodsFrom a cross-sectional study conducted in Long-term Care (LTC) facilities in Indonesia itching symptoms were obtained through a questionnaire. Skin conditions were assessed using photographs, stratum corneum (SC) hydration, skin pH, and skin blotting for biomarkers: albumin, interleukin 2 (IL2), nerve growth factor β (NGFβ), and thymic stromal lymphopoietin (TSLP). Association of skin measurements with the presence of skin blotting and trends analysis were conducted.ResultsAltogether, 564 LTC residents (average age, 70 years) participated. The SC hydration, skin pH, albumin, and NGFβ were associated with the presence of itch (p value= <0.001, <0.001, <0.001, and <0.001, respectively). The signal levels of skin blotting biomarkers were higher in itch group than in the non-itch group. Additionally, the higher quantile of SC hydration was significantly associated with a lower intensity level of NGFβ and TSLP (p value = 0.005, 0.003, respectively). The lower quantile of skin pH (better skin condition) was significantly associated with lower albumin, NGFβ, and TSLP (p value = 0.048, 0.035, and <0.001, respectively).ConclusionThe albumin, NGFβ, and TSLP could be a candidate for measurement of itchy skin among older adult with disrupted skin barrier function and local skin inflammation.  相似文献   
140.
To elucidate the clinical importance of estrogen receptor (ER) beta in breast cancer, 29 archival primary breast cancer specimens, six locally recurrent cancers, and five benign mammary tumors were examined histochemically for ERalpha, ERbeta and the proliferation markers Ki67 and cyclin A. In benign tumors, most epithelial cells contained ERbeta, but ERalpha was rare. In primary cancers, both ERalpha and ERbeta occurred in epithelial cells, the presence of ERbeta being associated with elevated expression of Ki67 and cyclin A, and ERalpha with decreased levels. Thus, the highest content of proliferation markers was seen in primary cancers that were ERalpha(-) ERbeta(+). Most Ki67-containing cells coexpressed ERbeta, but few showed ERalpha. In locally recurring cancers, ERalpha, ERbeta, and Ki67 were more highly expressed than in the corresponding primary tumors, and many cells containing ERbeta, but few with ERalpha, expressed Ki67. Surprisingly, ERbeta, but not ERalpha, was seen in the stromal cells of both primary and recurrent cancers. Because the response of breast cancers to tamoxifen therapy is correlated with the presence of ERalpha, cancer cells that lack ERalpha but contain ERbeta and proliferation markers represent a novel population of apparently proliferating cells that probably are not targeted by the current antiestrogens. Thus, appropriate ERbeta-specific ligands, perhaps in combination with tamoxifen, may be useful in improving the treatment of breast cancers.  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