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   6459篇
  免费   383篇
  国内免费   29篇
耳鼻咽喉   87篇
儿科学   162篇
妇产科学   96篇
基础医学   767篇
口腔科学   131篇
临床医学   395篇
内科学   1597篇
皮肤病学   183篇
神经病学   489篇
特种医学   186篇
外科学   955篇
综合类   29篇
一般理论   4篇
预防医学   255篇
眼科学   245篇
药学   649篇
中国医学   18篇
肿瘤学   623篇
  2023年   55篇
  2022年   84篇
  2021年   163篇
  2020年   91篇
  2019年   129篇
  2018年   147篇
  2017年   130篇
  2016年   167篇
  2015年   158篇
  2014年   210篇
  2013年   243篇
  2012年   375篇
  2011年   387篇
  2010年   209篇
  2009年   205篇
  2008年   325篇
  2007年   353篇
  2006年   359篇
  2005年   324篇
  2004年   341篇
  2003年   280篇
  2002年   269篇
  2001年   180篇
  2000年   194篇
  1999年   171篇
  1998年   72篇
  1997年   44篇
  1996年   37篇
  1995年   52篇
  1994年   47篇
  1993年   38篇
  1992年   105篇
  1991年   80篇
  1990年   75篇
  1989年   89篇
  1988年   92篇
  1987年   75篇
  1986年   65篇
  1985年   73篇
  1984年   41篇
  1983年   38篇
  1982年   18篇
  1980年   20篇
  1979年   24篇
  1975年   18篇
  1974年   17篇
  1972年   20篇
  1969年   26篇
  1968年   26篇
  1966年   15篇
排序方式: 共有6871条查询结果,搜索用时 31 毫秒
101.
BackgroundThe burden of COVID-19 on healthcare workers (HCWs) is reported to be increasing, yet the psychometric scales now in use evaluate only single aspects; few measure the pandemic-specific burden on HCWs comprehensively.ObjectiveTo develop a scale to quantify the physical, mental, and socioeconomic burden of the COVID-19 pandemic on HCWs.DesignScale development and cross-sectional survey.ParticipantsConsenting HCWs aged ≥20.Main MeasuresDevelopment of an item-list based on literature reviews and HCW panel input, evaluation of content validity and item selection using the Delphi method, psychometric testing conducted on HCWs, validity assessment by factor analyses and hypothesis verification, internal consistency evaluation by Cronbach’s alpha, test-retest analysis, and interpretability assessment.Key ResultsThrough the Delphi process, a 29-item pilot scale was generated. In psychometric testing, data from 863 HCWs contributed to the development of the final version of this scale, called Pandemic Burden Index twenty for HCWs (PBI-20), a 20-item scale to measure six domains: fatigue, fear of infection, inadequacy as a medical professional, mental health concerns, prejudice or discrimination, and anxiety about one’s livelihood and daily life. Factor analysis showed each factor corresponded to the six domains of this scale. Hypothesis verification showed the PBI-20 total score to be moderately to highly correlated with the Short Form 36 vitality score and mental health score and with intention of turnover. The PBI-20 had good internal consistency (Cronbach’s alpha 0.92). Test-retest analysis showed the intraclass correlation coefficient to be 0.70 and the minimal important change to be −7.0.ConclusionsThe psychometrically sound questionnaire we developed to measure pandemic-specific burdens for HCWs provides an understanding of comprehensive burdens on HCWs and may serve to evaluate interventions to reduce the burdens.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11606-023-08028-3.KEY WORDS: COVID-19, pandemic, burden, health personnel, psychometrics  相似文献   
102.
Histopathological diagnosis is the ultimate method of attaining the final diagnosis; however, the observation range is limited to the two‐dimensional plane, and it requires thin slicing of the tissue, which limits diagnostic information. To seek solutions for these problems, we proposed a novel imaging‐based histopathological examination. We used the multiphoton excitation microscopy (MPM) technique to establish a method for visualizing unfixed/unstained human breast tissues. Under near‐infrared ray excitation, fresh human breast tissues emitted fluorescent signals with three major peaks, which enabled visualizing the breast tissue morphology without any fixation or dye staining. Our study using human breast tissue samples from 32 patients indicated that experienced pathologists can estimate normal or cancerous lesions using only these MPM images with a kappa coefficient of 1.0. Moreover, we developed an image classification algorithm with artificial intelligence that enabled us to automatically define cancer cells in small areas with a high sensitivity of ≥0.942. Taken together, label‐free MPM imaging is a promising method for the real‐time automatic diagnosis of breast cancer.  相似文献   
103.
Background and aimsBreaking up sedentary periods, particularly with light activity, increases total energy expenditure (EE), and helps provide better glycemic control. However, the effects of activities of various intensities to interrupt prolonged sedentary time are unclear. The purpose of the present study was to examine potential differences in glycemic control and EE from breaking up sedentary time with short exercise bouts of different intensities.Methods and resultsNine overweight/obesity young men underwent whole body indirect calorimetry at 19:00 on day 1 and stayed overnight. After awakening on day 2, they performed short duration jogging every 30 min over 8 h (16-time bouts in total) under 3 different conditions with the same running distance: (1) lactate threshold (LT) for 2 min, (2) 60% LT for 200 s, and (3) onset of blood lactate accumulation (OBLA) for 75 s. The 24-h EE and interstitial glucose concentration (from 8:00 to 19:00 on day 2) was continuously measured throughout the trials. The standard deviation during intervention and indexes of postprandial of the interstitial glucose concentration was significantly lower at LT and OBLA than at 60% LT (p < 0.05). The 24-h EE was not significantly different among conditions, but EE at OBLA during intervention was slightly but significantly higher than at 60% LT and LT.ConclusionBreaking up sedentary time with short-duration jogging at LT and with OBLA intensities may have better glycemic control and increased use of carbohydrate as a fuel, while short-duration a jogging at OBLA intensity may increase EE.Trial registrationUMIN000041361.  相似文献   
104.
105.
BackgroundAlthough oxitropium bromide is used clinically as an anticholinergic drug (i.e., parasympathetic antagonist) to relax airway smooth muscle, we examined whether it has or does not have any effects on diaphragm muscle.MethodsThree treatment sets, an oxitropium bromide inhalation only group, an oxitropium bromide inhalation plus endotoxin injection group (in vivo) and an oxitropium bromide incubation group (in vitro) were studied as to diaphragm muscle contractile properties.ResultsOxitropium bromide inhalation shifted force-frequency curves upward at 2 h after inhalation (p < 0.05) and inhibited the decrease of force-frequency curves due to endotoxin injection in vivo. Incubation with oxitropium bromide of untreated diaphragm muscle and diaphragm muscle injected with endotoxin did not increase the force-frequency curves dose-dependently in vitro; however, it caused both types of muscle to be fatigue resistant.ConclusionsWe speculate that the increment of muscle contractility with the inhalation of oxitropium bromide was induced by the antagonization of musucarinic acetylcholine receptors (mAChR). In addition, the changes of fatigue resistance provoked by oxitropium bromide, which also is speculated to antagonize mAChR, may be beneficial in the treatment of patients with COPD.  相似文献   
106.
Abstract

Different approaches have been developed to improve the scaffold properties that provide structural support and biological interaction to achieve the desired environment for tissue regeneration. We previously reported that addition of human fibroblast growth factor 18 (hFGF18) to acryloyl group-modified cholesterol-bearing pullulan (CHPOA) nanogel-crosslinked (NanoClik) hydrogels that contain human bone morphogenetic protein 2 (hBMP2) stabilized bone healing in mouse calvarial defect model. In this study, we evaluated the use of disc-shaped dried nanogel-crosslinked gel as carriers of growth factors in order to seek possible clinical application in future. Both conventionally-dried NanoClik disc and nanogel-crosslinked porous (NanoCliP) disc made by freeze-drying that contained the growth factors induced bone healing but not as much as with NanoClik hydrogel application but addition of RGD peptides (RGD-NanoCliP disc) improved the healing. All type of discs showed the same biphasic ovalbumin-Alexa Fluor 488 protein release profile in vitro, an initial burst followed by a gradual sustained release more than one week, which was confirmed in vivo. Histological analysis showed remarkable new bone formation with more calcification in RGD-NanoCliP disc with the growth factors and the osteogenesis appeared to begin in the dura mater in contact with the disc. These observations suggest: (1) the fitness of the durable discs to the bone defect is a critical factor for bone healing, which is supplemented by addition of RGD peptides, (2) the porosity is suitable for osteoblast recruitment, (3) growth factor release pattern of the CHPOA nanogel based gels is ideal for bone healing.  相似文献   
107.
108.
109.
Despite possessing a limited number of neurones compared to vertebrates, honeybees show remarkable learning and memory performance, an example being ‘dance communication’. In this phenomenon, foraging honeybees learn the location of a newly discovered food source and transmit the information to nestmates by symbolic abdomen vibrating behaviour, leading to navigation of nestmates to the new food source. As an initial step toward understanding the detailed molecular mechanisms underlying the sophisticated learning and memory performance of the honeybee, we focused on the neural immediate early genes (IEGs), which are specific genes quickly transcribed after neural activity without de novo protein synthesis. Although these have been reported to play an essential role in learning and memory processes in vertebrates, far fewer studies have been performed in insects in this regard. From RNA‐sequencing analysis and subsequent assays, we identified three genes, Src homology 3 (SH3) domain binding kinase, family with sequence similarity 46 and GB47136, as novel neural IEGs in the honeybee. Foragers and/or orientating bees, which fly around their hives to memorize the positional information, showed induced expression of these IEGs in the mushroom body, a higher‐order centre essential for learning and memory, indicating a possible role for the novel IEGs in foraging‐related learning and memory processes in the honeybee.  相似文献   
110.

Background and Aim

Differential diagnosis of localized gallbladder lesions is challenging. The aim of the present study was to evaluate the utility of contrast‐enhanced harmonic endoscopic ultrasonography (CH‐EUS) for diagnosis of localized gallbladder lesions.

Methods

One hundred and twenty‐five patients with localized gallbladder lesions were evaluated by CH‐EUS between March 2007 and February 2014. This was a single‐center retrospective study. Utilities of fundamental B‐mode EUS (FB‐EUS) and CH‐EUS in the differentiation of gallbladder lesions and sludge plug were initially compared. Thereafter, these two examinations were compared with respect to their accuracy in the diagnosis of malignant lesions. Five reviewers blinded to the clinicopathological results evaluated microcirculation patterns in the vascular and perfusion images.

Results

In the differentiation between gallbladder lesions and sludge plug, FB‐EUS had a sensitivity, specificity, and accuracy of 82%, 100%, and 95%, respectively, whereas CH‐EUS had a sensitivity, specificity, and accuracy of 100%, 99%, and 99%, respectively. FB‐EUS‐based diagnosis of carcinomas based on tumor size and/or shape had a sensitivity, specificity, and accuracy of 61–87%, 71–88%, and 74–86%, respectively. Additional information regarding irregular vessel patterns in the vascular image and/or heterogeneous enhancement in the perfusion image on CH‐EUS increased the sensitivity, specificity, and accuracy for the diagnosis of carcinomas to 90%, 98%, and 96%, respectively. There was a significant difference between FB‐EUS and CH‐EUS in terms of carcinoma diagnosis.

Conclusion

CH‐EUS was useful for the evaluation of localized gallbladder lesions.  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