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   5139篇
  免费   338篇
  国内免费   22篇
耳鼻咽喉   42篇
儿科学   233篇
妇产科学   101篇
基础医学   588篇
口腔科学   115篇
临床医学   414篇
内科学   1114篇
皮肤病学   85篇
神经病学   257篇
特种医学   230篇
外科学   818篇
综合类   83篇
一般理论   2篇
预防医学   284篇
眼科学   179篇
药学   592篇
中国医学   48篇
肿瘤学   314篇
  2023年   47篇
  2022年   132篇
  2021年   196篇
  2020年   117篇
  2019年   138篇
  2018年   175篇
  2017年   123篇
  2016年   136篇
  2015年   153篇
  2014年   227篇
  2013年   272篇
  2012年   375篇
  2011年   414篇
  2010年   219篇
  2009年   177篇
  2008年   315篇
  2007年   308篇
  2006年   270篇
  2005年   225篇
  2004年   229篇
  2003年   192篇
  2002年   198篇
  2001年   59篇
  2000年   44篇
  1999年   54篇
  1998年   38篇
  1997年   28篇
  1996年   23篇
  1995年   28篇
  1994年   14篇
  1993年   26篇
  1992年   35篇
  1991年   37篇
  1990年   35篇
  1989年   31篇
  1988年   27篇
  1987年   28篇
  1986年   21篇
  1984年   35篇
  1983年   17篇
  1982年   21篇
  1981年   20篇
  1980年   22篇
  1979年   23篇
  1978年   13篇
  1975年   12篇
  1973年   18篇
  1972年   11篇
  1970年   14篇
  1968年   11篇
排序方式: 共有5499条查询结果,搜索用时 15 毫秒
71.
Introduction and Aim:The prognostic role of neutrophil to lymphocyte ratio (NLR) has been explored extensively in the literature. The aim of this meta-analysis was to evaluate the link between NLR and lymph node metastasis in gastric cancer. A method for increasing specificity and sensitivity of pre-treatment staging has implications on treatment algorithms and survival.Search Strategy:The relevant databases were searched as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses flowchart. After selection, 12 full text articles that met the inclusion criteria were included for quantitative analysis. 2 × 2 squares were generated using lymph node positive/negative, and NLR high/low data. The effect size for each study was calculated using the DerSimonian–Laird random effects model. P values were calculated using the chi-square method. Finally publication bias was evaluated. All statistics were calculated using R Studio.Results:Meta-analysis showed a 1.90 times (odds ratio, with 95% CI 1.52–2.38) increase in risk of positive lymph node status with high neutrophil to lymphocyte ratio. This has significant implications for cancer screening and staging, as NLR is a highly reproducible, cost-effective, and widely available prognostic factor for gastric cancer patients. Additionally, high or low NLR values may have implications for management pathways. Patients with lymph node metastasis can be offered neoadjuvant chemotherapy, avoiding salvage therapy in the form of adjuvant chemoradiotherapy, which is poorly tolerated.Conclusion:This meta-analysis shows an association between NLR and positive lymph node status in gastric cancer patients with implications for staging, as well as preoperative personalisation of therapy.  相似文献   
72.
BackgroundCalcitonin gene-related peptide (CGRP) inhibitors have been developed as options for treatment of chronic and episodic migraine. We present our experience of the use of erenumab in a tertiary headache centre.MethodsThis was a prospective clinical audit of all patients commenced on erenumab following a locally agreed pathway and criteria over a consecutive period. Patients received monthly erenumab 140 mg for 3 months. Data were collected prospectively at baseline and 3 months follow up.ResultsOne hundred three patients were commenced on erenumab during the study period. Patients had tried a median of 7 previous prophylactics, including onabotulinum toxin A in 94%. At 3 months there was a reduction in median total (28 to 20, 29% reduction, p < 0.0001) and severe (15 to 5, 67% reduction, p < 0.0001) headache days. 39.8% of patients achieved at least a 30% reduction in total headache days; 61.8% of patients achieved at least a 50% reduction in severe headache days. Meeting either of these thresholds was considered a positive response, 68% of patients achieved this. Presence of daily headache pattern was negatively associated with response, (56% response vs. 90% without daily headache, p = 0.0003). There was no association between age, gender, presence of medication overuse or number of previously tried prophylactic treatments and response to erenumab. 43% of patients reported at least one adverse effect, most commonly constipation (26%); treatment was discontinued in 3 patients due to adverse effects.ConclusionsErenumab was an effective treatment for chronic migraine in this treatment resistant population over 3 months of follow up. Presence of daily headache predicted poorer response but there was still a significant positive response rate in this group.  相似文献   
73.
Purpose:To compare multicolor imaging (MCI) with Optos color fundus photography (OCFP) for the evaluation of morphology and extent of preretinal membranes in diabetic tractional retinal detachments (TRD).Methods:In this retrospective study, 30 eyes with diabetic TRDs were imaged using the MCI feature of the Heidelberg Spectralis Spectral-domain optical coherence tomography (SD-OCT) and color photo using the Optos Daytona ultra-widefield fundus camera. Two investigators independently graded and determined the agreeability between the two modalities with respect to the extent of the TRD and preretinal membranes on the SD-OCT B-scan images.Results:The MCI provided better visualization of the attachments and traction points of the posterior hyaloid face and preretinal membranes and is comparable to the SD-OCT B-scan images. The inter-rater agreeability rates for OCFP had a Kappa (κ) value of 0.37, while the MCI had a κ value of 0.46. When comparing between images of different wavelengths, grading using infrared reflectance (IR) had a poor agreement (−0.04 ± 0.04) while green reflectance (GR) (0.46 ± 0.32) and blue reflectance (BR) (0.53 ± 0.19) had a moderate agreement. The composite MCI and GR images also had comparatively higher intraclass coefficient when compared to the OCFP (0.25 [−0.09–0.55]) and IR (−0.03 [−0.39–0.34]) images.Conclusion:MCI is more sensitive for determining the extent of TRDs and for the detection of secondary membranes when compared to OCFP, thus, aiding in better surgical planning.  相似文献   
74.
The fabrication of fiber-reinforced metal matrix composites (MMCs) mainly consists of two stages: infiltration and solidification, which have a significant influence on the properties of MMCs. The present study is primarily focused on the simulation of the solidification process and the effect of the active cooling of fibers with and without nickel coating for making the continuous carbon fiber-reinforced aluminum matrix composites. The thermomechanical finite element model was established to investigate the effects of different cooling conditions on the temperature profile and thermal stress distributions based on the simplified physical model. The predicted results of the temperature distribution agree well with the results of the references. Additionally, a three-dimensional cellular automata (CA) finite element (FE) model is used to simulate the microstructure evolution of the solidification process by using ProCAST software. The results show that adding a nickel coating can make the heat flux smaller in the melt, which is favorable for preventing debonding at the coating/fiber and alloy interface and obtaining a finer microstructure. In the presence of the nickel coating, the number of grains increases significantly, and the average grain size decreases, which can improve the properties of the resultant composite materials. Meanwhile, the predicting results also show that the interfaces of fiber–coating, fiber–melt, and coating–melt experience higher temperature gradients and thermal stresses. These results will lead to the phenomenon of stress concentration and interface failure. Thus, it was demonstrated that these simulation methods could be helpful for studying the solidification of fiber-reinforced MMCs and reducing the number of trial-and-error experiments.  相似文献   
75.
Purpose:To assess the feasibility of measuring patients’ visual acuity (VA) in their homes by their caregivers.Methods:Patients consulting in a tertiary eye care institute were prospectively enrolled with informed consent. All underwent standard COMPlog distance VA testing. Patients and caregivers were oriented to test distance VA using the Peek Acuity app. The app was installed on the caregiver’s or patient’s smartphone. The patient’s VA was measured by the caregiver in the clinic (baseline value) under supervision. After 1 week, the caregivers recorded the patient’s VA with the Peek Acuity app at their home and reported the value in a telephone consultation. A questionnaire to assess the ease of using the app was administered at both the baseline visit and 1 week later.Results:A total of 100 patients (age group: 13 to 76 years) and 100 caregivers (age group: 17 to 65 years) participated. VA measurements with the Peek Acuity app were comparable with COMPlog (P > 0.1) both during the baseline and after 1-week measurement, regardless of the underlying ocular condition or educational level of the caregivers/patients. Most caregivers (95%) felt the app was easy to use.Conclusion:Though the Peek Acuity app was originally developed for health care workers to be used in field visits, we found that with proper orientation, the layperson can also use it. Such orientation can enable caregivers to effectively measure VA at home. Such a tool would enhance teleophthalmology consultations and can minimize the need for short follow-up visits.  相似文献   
76.
77.
78.
3-Phenoxybenzoic acid (3-PBA) and 4-hydroxy-3-phenoxybenzoic acid (OH-PBA) are the two common metabolites for most pyrethroid insecticides. A rapid, sensitive, and eco-friendly method has been developed based on ultrasound-assisted dispersive liquid–liquid microextraction (DLLME) coupled to large volume injection–gas chromatography–tandem mass spectrometry for the simultaneous determination of pyrethroid metabolites in rat brain treated with cypermethrin (CYP). Brain samples were homogenized in methanol (disperser solvent) followed by derivatization with methyl chloroformate (MCF) and extraction using DLLME. Factors that influence the extraction and derivatization efficiency such as type and volume of extraction and disperser solvent, sonication time, pH, ionic strength, and volumes of MCF and pyridine were optimized. Under optimized conditions, the limits of detection were 1 and 4 ng/g for 3-PBA and OH-PBA, respectively. Mean recoveries of pyrethroid metabolites in rat brain were in the range of 83–95 %. The developed method was successfully applied for determination of 3-PBA and OH-PBA in brain samples of CYP-treated rats. The developed method can be adopted for rapid and sensitive analysis of pyrethroid metabolites in toxicological and forensic laboratories.  相似文献   
79.
It is quite challenging to deal with the health care needs of migrant populations in general, especially pregnant women, due to their diverse sociopolitical and cultural beliefs and practices. In this article, we aim to examine and understand the food habits and beliefs of pregnant British Bangladeshis using qualitative methods. Our results indicate some positive associations between the increased intakes of particular foods to ensure healthy outcomes. We also note that migration affects pregnant Bangladeshi women's physical and mental conditions. We conclude that effective health care and awareness about traditional food beliefs and habits, and their subsequent reflection into the national and local policy agendas, may bring forth positive changes and improve the overall health of pregnant women.  相似文献   
80.
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