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   8305篇
  免费   631篇
  国内免费   30篇
耳鼻咽喉   105篇
儿科学   208篇
妇产科学   231篇
基础医学   1241篇
口腔科学   152篇
临床医学   1018篇
内科学   1676篇
皮肤病学   199篇
神经病学   917篇
特种医学   261篇
外科学   828篇
综合类   67篇
一般理论   1篇
预防医学   724篇
眼科学   118篇
药学   551篇
中国医学   40篇
肿瘤学   629篇
  2023年   92篇
  2022年   74篇
  2021年   336篇
  2020年   251篇
  2019年   263篇
  2018年   300篇
  2017年   224篇
  2016年   282篇
  2015年   324篇
  2014年   368篇
  2013年   502篇
  2012年   730篇
  2011年   740篇
  2010年   416篇
  2009年   368篇
  2008年   572篇
  2007年   506篇
  2006年   492篇
  2005年   479篇
  2004年   401篇
  2003年   347篇
  2002年   339篇
  2001年   43篇
  2000年   27篇
  1999年   32篇
  1998年   56篇
  1997年   35篇
  1996年   30篇
  1995年   32篇
  1994年   33篇
  1993年   20篇
  1992年   14篇
  1991年   13篇
  1990年   13篇
  1989年   13篇
  1988年   18篇
  1987年   9篇
  1986年   6篇
  1985年   8篇
  1984年   15篇
  1983年   12篇
  1982年   19篇
  1981年   6篇
  1980年   8篇
  1978年   11篇
  1977年   6篇
  1975年   10篇
  1972年   5篇
  1937年   5篇
  1928年   5篇
排序方式: 共有8966条查询结果,搜索用时 15 毫秒
1.
AIM: To investigate the effect of broccoli sprouts juice in preventing lens protein aggregation in diabetic rat model. METHODS: Totally 25 male Wistar rats were divided into negative control group, diabetic group without juice treatment as positive control and diabetic group given broccoli sprouts juice 0.25, 0.5 and 1 g/d for 28d. Diabetic rat model was obtained by administering a single dose streptozotocin 65 mg/kg intraperitoneal. At the end of the study, all rats were examined for fasting blood sugar level (FBS), visual cataract score using slit lamp biomicroscope and lens αB-crystallin expression using Western blot method. Statistical analysis was performed using one way ANOVA with post hoc test, correlation test, and simple linear regression. RESULTS: Positive control group had the highest cataract score and lens aggregated αB-crystallin expression. Broccoli sprout juice dose of 1 g/d group had the mildest cataract score, as well as the expression of lens aggregated αB-crystallin compared to treatments groups 1 and 2, opposite to lens native αB-crystallin expression. The broccoli sprout juice groups gave a significant decrease in cataract score, and also in lens aggregated αB-crystallin expression in diabetic rat models (P<0.05). CONCLUSION: Broccoli sprout juice has a significant effect in preventing lens protein aggregation in diabetic rat model. The higher dose gives better visual cataract scores, lower lens aggregated αB-crystallin expression and higher lens native αB-crystallin expression.  相似文献   
2.
3.
Bacterial biofilms are a cause of contamination in a wide range of medical and biological areas. Ultrasound is a mechanical energy that can remove these biofilms using cavitation and acoustic streaming, which generate shear forces to disrupt biofilm from a surface. The aim of this narrative review is to investigate the literature on the mechanical removal of biofilm using acoustic cavitation to identify the different operating parameters affecting its removal using this method. The properties of the liquid and the properties of the ultrasound have a large impact on the type of cavitation generated. These include gas content, temperature, surface tension, frequency of ultrasound and acoustic pressure. For many of these parameters, more research is required to understand their mechanisms in the area of ultrasonic biofilm removal, and further research will help to optimise this method for effective removal of biofilms from different surfaces.  相似文献   
4.

Statement of problem

Polymeric material for 3-dimensional printing can be used to fabricate occlusal devices. However, information about fracture resistance and wear is scarce.

Purpose

The purpose of this in vitro study was to investigate the fracture resistance and 2-body wear of 3-dimensional–printed (3DP) (FotoDent splint; Dreve Dentamid GmbH), milled polymethylmethacrylate (CAM) (Temp Basic; Transpa 95H16, Zirkonzahn GmbH), and conventionally fabricated polymethylmethacrylate (CAST) (Castdon; Dreve Dentamid GmbH) occlusal devices.

Material and Methods

A total of 96 occlusal devices were prepared according to the 3 different manufacturing techniques 3DP, CAM, and CAST (n=32). For each manufacturing technique, specimens were further divided into initial fracture resistance tests (n=16) and artificial aging in the mastication simulator (50 N, 37°C) with 2-body wear followed by fracture resistance tests (n=16). The fracture resistance was determined using a universal testing machine (1 mm/min). The wear was measured after 20?000 and 120?000 mastication cycles with the replica technique, mapped with a laser scanner, and quantified in R software. Data were analyzed using a 2-way ANOVA followed by a 1-way ANOVA with Scheffé or Games-Howell post hoc tests, repeated measures ANOVA with corrected Greenhouse-Geisser P values, and the Levene, Mann-Whitney, and paired t tests (α=.05).

Results

CAM presented higher initial fracture resistance than 3DP or CAST (P<.001). After mastication simulation, CAM followed by 3DP showed higher fracture resistance than CAST (P<.001). Mastication simulation decreased the fracture resistance for CAM and CAST (P<.001) but not for 3DP (P=.78). Three-dimensional–printed occlusal devices showed the highest material volume loss, followed by CAM and the lowest in CAST (P<.001).

Conclusions

Three-dimensional–printed occlusal devices showed lower wear resistance and lower fracture resistance than those milled or conventionally fabricated. Therefore, only short-term application in the mouth is recommended. Further developments of occlusal device material for 3-dimensional printing are necessary.  相似文献   
5.
Methadone has several unique characteristics that make it an attractive option for pain relief in serious illness, but the safety of methadone has been called into question after reports of a disproportionate increase in opioid-induced deaths in recent years. The American Pain Society, College on Problems of Drug Dependence, and the Heart Rhythm Society collaborated to issue guidelines on best practices to maximize methadone safety and efficacy, but guidelines for the end-of-life scenario have not yet been developed. A panel of 15 interprofessional hospice and palliative care experts from the U.S. and Canada convened in February 2015 to evaluate the American Pain Society methadone recommendations for applicability in the hospice and palliative care setting. The goal was to develop guidelines for safe and effective management of methadone therapy in hospice and palliative care. This article represents the consensus opinion of the hospice and palliative care experts for methadone use at end of life, including guidance on appropriate candidates for methadone, detail in dosing, titration, and monitoring of patients' response to methadone therapy.  相似文献   
6.
7.
8.
9.
10.
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