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   1302篇
  免费   87篇
  国内免费   6篇
耳鼻咽喉   26篇
儿科学   30篇
妇产科学   18篇
基础医学   160篇
口腔科学   36篇
临床医学   88篇
内科学   365篇
皮肤病学   31篇
神经病学   49篇
特种医学   18篇
外科学   213篇
综合类   35篇
一般理论   1篇
预防医学   83篇
眼科学   47篇
药学   97篇
中国医学   30篇
肿瘤学   68篇
  2023年   8篇
  2022年   33篇
  2021年   41篇
  2020年   28篇
  2019年   67篇
  2018年   53篇
  2017年   34篇
  2016年   33篇
  2015年   27篇
  2014年   43篇
  2013年   77篇
  2012年   96篇
  2011年   120篇
  2010年   49篇
  2009年   45篇
  2008年   67篇
  2007年   76篇
  2006年   56篇
  2005年   58篇
  2004年   61篇
  2003年   46篇
  2002年   36篇
  2001年   21篇
  2000年   30篇
  1999年   24篇
  1998年   7篇
  1997年   3篇
  1995年   5篇
  1994年   7篇
  1992年   10篇
  1991年   12篇
  1990年   6篇
  1989年   13篇
  1988年   10篇
  1987年   9篇
  1986年   11篇
  1985年   5篇
  1984年   3篇
  1983年   6篇
  1979年   8篇
  1977年   2篇
  1975年   5篇
  1974年   8篇
  1973年   2篇
  1972年   3篇
  1971年   2篇
  1970年   3篇
  1969年   5篇
  1968年   5篇
  1967年   4篇
排序方式: 共有1395条查询结果,搜索用时 15 毫秒
31.
The purpose of this study was to provide information concerning the possible early effects of smoking on measures of respiratory capacity and control in young adult female smokers vs. nonsmokers. In particular, maximum performance test results (vital capacity and maximum phonation time) and measures of air pressures and airflows during voiceless, stop‐plosive productions were analysed. Subjects were 45 female nonsmokers and 30 female smokers (total n = 75) between the ages of 18–30 years. For the purposes of this study, a smoker was defined as any subject who, at the time of this study, had smoked at least two cigarettes per day for at least 1 year. All of the subjects in the nonsmoker category were those who, at the time of this study, did not smoke and who had not smoked for at least 5 years prior to the study. Vital capacity measures were conducted using a hand‐held digital spirometer, while maximum phonation productions and voiceless, stop‐plosive pressures and flows were recorded and measured using the Aerophone II Model 6800 (Kay Elemetrics Corp., Lincoln Park, NJ). Results showed significantly lower vital capacities and maximum phonation times in smokers vs. nonsmokers. The maximum phonation time task was also produced with significantly higher mean airflow rates in smokers than nonsmokers. In addition, the smokers were observed to produce significantly greater peak and mean pressures during the voiceless stop‐plosive task than the nonsmokers. A weak, but significant correlation was observed between the number of days the subject had smoked and the mean pressure produced during the voiceless, stop‐plosive task. The findings of reduced respiratory capacity and control in smokers may be associated with factors such as increased bronchial reactivity secondary to exposure to cigarette smoke and/or mild airway obstruction, increased airflow secondary to increased glottal gap size during phonation, and increased vocal fold mass and/or inefficiency in vocal fold closure. The findings of this study indicate that decrements in respiratory capacity and control may occur even in relatively young smokers who have only been smoking for a comparatively short time  相似文献   
32.
The advent of antibiotics revolutionized medical care resulting in significantly reduced mortality and morbidity caused by infectious diseases. However, excessive use of antibiotics has led to the development of antibiotic resistance and indeed, the incidence of multidrug-resistant pathogens is considered as a major disadvantage in medication strategy, which has led the scholar's attention towards innovative antibiotic sources in recent years. Medicinal plants contain a variety of secondary metabolites with a wide range of therapeutic potential against the resistant microbes. Therefore, the aim of this review is to explore the antibacterial potential of traditional herbal medicine against bacterial infections. More than 200 published research articles reporting the therapeutic potential of medicinal plants against drug-resistant microbial infections were searched using different databases such as Google Scholar, Science Direct, PubMed and the Directory of Open Access Journals (DOAJ), etc., with various keywords like medicinal plants having antibacterial activities, antimicrobial potentials, phytotherapy of bacterial infection, etc. Articles were selected related to the efficacious herbs easily available to local populations addressing common pathogens. Various plants such as Artocarpus communis, Rheum emodi, Gentiana lutea L., Cassia fistula L., Rosemarinus officinalis, Argemone maxicana L, Hydrastis canadensis, Citrus aurantifolia, Cymbopogon citrates, Carica papaya, Euphorbia hirta, etc, were found to have significant antibacterial activities. Although herbal preparations have promising potential in the treatment of multidrug-resistant bacterial infection, still more research is required to isolate phytoconstituents, their mechanism of action as well as to find their impacts on the human body.  相似文献   
33.
34.
35.
Graefe's Archive for Clinical and Experimental Ophthalmology - Current methods to analyse the globe position, including Hertel exophthalmometry and computed tomography (CT), are limited to the...  相似文献   
36.
BACKGROUND & AIMS: Digestive and liver diseases are associated with substantial morbidity and mortality in the United States. Statistics about the incidence, prevalence, mortality, and resource utilization of digestive and liver diseases in the United States may be cumbersome to obtain because they are scattered in multiple sources. These data may be useful for policy makers, grant applicants, and authors. METHODS: Data on the most common gastrointestinal and liver diseases were collected from large publicly available national databases. Information was collected on inpatient and outpatient gastrointestinal complaints and diagnoses, gastrointestinal cancers, and deaths from common liver diseases. RESULTS: The leading gastrointestinal complaint prompting an outpatient visit is abdominal pain, with 12.2 million annual visits, followed by diarrhea, nausea, and vomiting. Abdominal pain is the leading outpatient gastrointestinal diagnosis, accounting for 5.2 million visits annually, followed by gastroesophageal reflux disease, with 4.5 million visits. Gallstone disease is the most common inpatient diagnosis, with 262,411 hospitalizations and a median inpatient charge of USD$11,584. Colorectal cancer is the most common gastrointestinal cause of death and is the most common gastrointestinal cancer, with an incidence of 54 per 100,000. Among gastrointestinal cancers, primary liver cancer had the highest increase in incidence from 1992 to 2000. CONCLUSIONS: Gastrointestinal and liver diseases are associated with significant outpatient and inpatient healthcare utilization. Following trends in utilization is important for determining allocation of resources for health care and research.  相似文献   
37.
International Journal of Diabetes in Developing Countries - The present study aimed to evaluate the expression of microRNA-155 (miR-155) in type 2 diabetes mellitus (T2DM) and assess its...  相似文献   
38.
Previous studies have suggested the involvement of tumour-suppressor genes on chromosomes 8p, 22q and 18q (DCC) in prostate cancer. The aim of this study was to further characterize these regions. We investigated 20 polymorphic regions on the 3 chromosome arms in 43 cancers and 10 cases of benign prostatic hyperplasia (BPH). Allelic loss was observed in 72% of cancers on 8p, 16% on 22q and 24% at DCC. For BPH, loss was observed in 20% on 8p and in 12% at DCC. The low incidence of LOH on 22q implies that this locus has no significant role in prostate carcinogenesis. At DCC, although the overall incidence was low, tumours with LOH were mostly of high grade or had metastases, suggesting a role for this gene in prostate cancer progression. On chromosome 8p, 29% of cancers had deletions at the LPL locus on 8p22 and 60% had deletions within a region flanked by the markers D8S339 and ANKI on 8p11.1-p21.1. Within this region, 2 distinct areas of allelic loss were observed, at one or both ANKI and D8S255, and in the region defined by the markers D8S259-D8S505. For the regions 8p22 and ANKI-D8S255, tumours with metastases had a greater frequency of LOH compared to non-metastasizing tumours, suggesting the presence of putative metastasis-suppressor genes in these regions. © 1996 Wiley-Liss, Inc.  相似文献   
39.
40.
This study describes for the first time the preparation of re-dispersible surfactant-free dry eicosane oil emulsion using cellulose nanocrystals (CNCs) using the freeze-drying technique. Surface properties of CNCs constitute a critical point for the stability of o/w emulsions and thus can affect both the droplet size and dispersion properties of the emulsion. Therefore, surface modification of CNCs was performed to understand its effect on the size of the obtained re-dispersible dry o/w eicosane emulsion. Decoration of the CNC surface with metal and metal oxide nanoparticles was conducted through the available alcoholic groups of glycosidic units of CNC, which played a dual role in reducing and stabilizing nanoparticles. Of these nanoparticles, silver (AgNPs), gold (AuNPs), copper oxide (CuO-NPs), and iron oxide (Fe3O4-NPs) nanoparticles were prepared via a facile route using alkali activated CNCs. Thorough characterizations pertaining to the as-prepared nanoparticles and their re-dispersible dry eicosane o/w emulsions were investigated using UV-vis spectroscopy, TEM, XRD, particle size, zeta potential, and STEM. Results confirmed the ability of CNCs to stabilize and/or reduce the formed nanoparticles with different sizes and shapes. These nanoparticles showed different shapes and surface charges accompanied by individual morphologies, reflecting on the stability of the re-dispersed dry eicosane emulsions with droplet sizes varying from 1.25 to 0.5 μm.

Schematic diagram for the detailed preparation of dry eicosane o/w emulsions.  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