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   2043篇
  免费   93篇
  国内免费   14篇
耳鼻咽喉   23篇
儿科学   62篇
妇产科学   24篇
基础医学   200篇
口腔科学   55篇
临床医学   167篇
内科学   529篇
皮肤病学   25篇
神经病学   92篇
特种医学   80篇
外科学   460篇
综合类   61篇
一般理论   4篇
预防医学   149篇
眼科学   48篇
药学   89篇
中国医学   7篇
肿瘤学   75篇
  2024年   1篇
  2023年   34篇
  2022年   108篇
  2021年   157篇
  2020年   80篇
  2019年   87篇
  2018年   109篇
  2017年   71篇
  2016年   64篇
  2015年   78篇
  2014年   107篇
  2013年   117篇
  2012年   183篇
  2011年   171篇
  2010年   116篇
  2009年   102篇
  2008年   102篇
  2007年   88篇
  2006年   93篇
  2005年   69篇
  2004年   63篇
  2003年   62篇
  2002年   33篇
  2001年   6篇
  2000年   4篇
  1999年   6篇
  1998年   10篇
  1997年   1篇
  1996年   1篇
  1995年   2篇
  1994年   4篇
  1993年   2篇
  1992年   2篇
  1991年   4篇
  1990年   5篇
  1989年   2篇
  1988年   3篇
  1985年   1篇
  1983年   1篇
  1979年   1篇
排序方式: 共有2150条查询结果,搜索用时 15 毫秒
101.
Chronic obstructive pulmonary disease (COPD) is a major disease in Asia. However, how to manage specifically Asian COPD patients has not been proposed. Awareness of COPD is very low and underdiagnosis/undertreatment is common in Asian countries. Low utilization of pulmonary function test and inhalers is also a problem. Moreover, high smoking prevalence and air pollution are barriers to managing Asian patients with COPD. The relatively low body mass index of Asian patients with COPD can increase their risk for experiencing adverse effects from COPD drugs. Physicians should consider the unique features of Asian populations with COPD such as the high prevalence rates of bronchiectasis and tuberculosis‐destroyed lungs, biomass smoke exposure and parasitic infection.  相似文献   
102.
To avoid time-consuming, costly, and laborious experimental tests that require skilled personnel, an effort has been made to formulate the depth of wear of fly-ash concrete using a comparative study of machine learning techniques, namely random forest regression (RFR) and gene expression programming (GEP). A widespread database comprising 216 experimental records was constructed from available research. The database includes depth of wear as a response parameter and nine different explanatory variables, i.e., cement content, fly ash, water content, fine and coarse aggregate, plasticizer, air-entraining agent, age of concrete, and time of testing. The performance of the models was judged via statistical metrics. The GEP model gives better performance with R2 and ρ equals 0.9667 and 0.0501 respectively and meet with the external validation criterion suggested in the previous literature. The k-fold cross-validation also verifies the accurateness of the model by evaluating R2, RSE, MAE, and RMSE. The sensitivity analysis of GEP equation indicated that the time of testing is the influential parameter. The results of this research can help the designers, practitioners, and researchers to quickly estimate the depth of wear of fly-ash concrete thus shortening its ecological susceptibilities that push to sustainable and faster construction from the viewpoint of environmentally friendly waste management.  相似文献   
103.
ObjectiveRosacea is a common inflammatory cutaneous condition with a complex yet unknown etiopathogenesis. Diet and certain food items are known to trigger or worsen rosacea symptoms, but conflicting and often inconsistent advice is given to patients regarding this link. We provide an up-to-date literature review on the relationship between rosacea and diet.MethodsUsing the keywords “alcohol,” “diet,” “flushing,” “food,” “inflammation,” “rosacea,” “skin-gut axis” and “spice” we systemically searched the databases PubMed, MEDLINE and EMBASE for English-language articles in July 2020.ResultsThe most frequently reported triggers implicated in rosacea include alcohol, spicy food, cinnamaldehyde-containing foods (e.g., tomatoes, citrus fruits, chocolate), hot drinks, and histamine-rich foods (e.g., aged cheese, wine, processed meats). Some food items appear to play a protective role, such as omega-3, which appears to protect against ocular rosacea. The relationship between certain food items and the subtype of rosacea is varied, with inconsistent results shown in the few studies that examined this. As an example, alcohol worsens flushing and fatty food triggers both erythematotelangiectatatic and phymatous rosacea in susceptible individuals.ConclusionWhile several food types appear to be associated with exacerbation of rosacea, there are no recommendations that can be applied to all patients. Further studies are needed to examine the exact link between diet and rosacea subtypes.  相似文献   
104.
Correction for ‘Development and in vitro evaluation of κ-carrageenan based polymeric hybrid nanocomposite scaffolds for bone tissue engineering’ by Muhammad Umar Aslam Khan et al., RSC Adv., 2020, 10, 40529–40542. DOI: 10.1039/D0RA07446B.

The authors regret errors in Fig. 9 in the original article. The corrected Fig. 9 is shown below where all three +ive control panels and the 72 h CG-g-Aac-2 panel have been replaced.Open in a separate windowFig. 9Cell morphology of MC3T3-E1 against +ive control and all scaffold samples (CG-g-AAc1, CG-g-AAc2 and CG-g-AAc3) under standard in vitro conditions. The red arrows show thread-like morphology and the yellow arrows exhibits well-grown morphology of the cells.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.  相似文献   
105.
Ebastine, is an antihistamine drug that exerts its effect upon oral administration in humans for the treatment of allergic contact dermatitis (ACD), it also has some systemic side effects like gastric distress, headache, drowsiness, and epistaxis. Moreover, topical corticosteroids are used for treatment of ACD, which causes the human skin to lose its thickness and elasticity. Hence, ebastine-loaded solid lipid nanoparticles (E-SLNs) were prepared and their topical efficacy against allergic contact dermatitis was determined. Compritol 888 ATO and tween 80 were used to prepare E-SLNs by cold dilution of the hot micro-emulsion. E-SLNs were optimized statistically by employing a central composite design using Design-Expert® version 11.0. Optimized E-SLNs showed spherical surface morphology, zeta potential of −15.6 ± 2.4 mV, PDI of 0.256 ± 0.03, and particle sizes of 155.2 ± 1.5 nm and th eentrapment efficiency of ebastine was more than 78%. Nanoparticles were characterized using FT-IR, XRD, and TEM. An E-SLNs loaded hydrogel was prepared using chitosan as a gelling agent and glutaraldehyde as a crosslinker. In vitro drug release studies performed for 24 hours on the E-SLNs dispersion and E-SLNs loaded hydrogel showed a sustained release of maximum 82.9% and 73.7% respectively. In vivo studies were conducted on BALB/c mice to evaluate the topical efficacy of the E-SLNs loaded hydrogel for allergic contact dermatitis. ACD was induced on the ear using picryl chloride solution. After induction, ears were treated daily with the E-SLNs loaded hydrogel for 15 days. Swelling behavior, mast cell count, and histopathological studies of the ear confirmed that the hydrogel alleviated the symptoms of allergic contact dermatitis.

Ebastine exerts its effect upon oral administration in humans for the treatment of allergic contact dermatitis (ACD), but it has some systemic side effects. Hence, ebastine-SLNs loaded hydrogel was prepared to increase topical efficacy of ebastine.  相似文献   
106.
There is increasing concern regarding alleviating world energy demand by determining an alternative to petroleum-derived fuels due to the rapid depletion of fossil fuels, rapid population growth, and urbanization. Biodiesel can be utilized as an alternative fuel to petroleum-derived diesel for the combustion engine. At present, edible crops are the primary source of biodiesel production. However, the excessive utilization of these edible crops for large-scale biodiesel production might cause food supply depletion and economic imbalance. Moreover, the utilization of edible oil as a biodiesel feedstock increases biodiesel production costs due to the high price of edible oils. A possible solution to overcome the existing limitations of biodiesel production is to utilize non-edible crops oil as a feedstock. The present study was conducted to determine the possibility and challenges of utilizing non-edible oil as a potential feedstock for biodiesel production. Several aspects related to non-edible oil as a biodiesel feedstock such as overview of biodiesel feedstocks, non-edible oil resources, non-edible oil extraction technology, its physicochemical and fatty acid properties, biodiesel production technologies, advantages and limitation of using non-edible oil as a feedstock for biodiesel production have been reviewed in various recent publications. The finding of the present study reveals that there is a huge opportunity to utilize non-edible oil as a feedstock for biodiesel production.

There is increasing concern regarding alleviating world energy demand by determining an alternative to petroleum-derived fuels due to the rapid depletion of fossil fuels, rapid population growth, and urbanization.  相似文献   
107.
Methane is the main component of biogas, which could be used as a renewable energy source for electricity, source of heat, and biofuel production after upgrading from biogas. It also contains toxic compounds which cause environmental and human health problems. Therefore, in this work, the removal of a toxic compound (toluene) from methane gas was studied using a dielectric barrier discharge (DBD) reactor. It was observed that the removal of the toxic compound could be achieved from methane carrier gas using a dielectric barrier discharge reactor, and it depends on plasma input power. The maximum removal of the toxic compound was 85.9% at 40 W and 2.86 s. The major gaseous products were H2 and lower hydrocarbons (LHC) and the yield of these products also increases with input power. In the current study, the yield of gaseous products depends on the decomposition of toxic compounds and methane, because the decomposition of methane also produces H2 and lower hydrocarbons. The percentage yield of H2 increases from 0.43–4.74%. Similarly, the yield of LHC increases from 0.56–7.54% under the same reaction conditions. Hence, input power promoted the decomposition of the toxic compound and enhanced the yield of gaseous products.

The removal of toluene as a toxic volatile organic compound from methane gas, which is the major component of biogas, is carried out using a non-thermal plasma dielectric barrier discharge reactor.  相似文献   
108.
109.
110.
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