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   1580篇
  免费   102篇
  国内免费   5篇
耳鼻咽喉   10篇
儿科学   88篇
妇产科学   39篇
基础医学   199篇
口腔科学   23篇
临床医学   167篇
内科学   347篇
皮肤病学   18篇
神经病学   125篇
特种医学   39篇
外科学   129篇
综合类   27篇
一般理论   2篇
预防医学   119篇
眼科学   50篇
药学   167篇
中国医学   8篇
肿瘤学   130篇
  2024年   6篇
  2023年   22篇
  2022年   26篇
  2021年   62篇
  2020年   40篇
  2019年   38篇
  2018年   57篇
  2017年   55篇
  2016年   59篇
  2015年   72篇
  2014年   75篇
  2013年   106篇
  2012年   117篇
  2011年   129篇
  2010年   65篇
  2009年   69篇
  2008年   80篇
  2007年   79篇
  2006年   66篇
  2005年   97篇
  2004年   71篇
  2003年   55篇
  2002年   41篇
  2001年   25篇
  2000年   35篇
  1999年   25篇
  1998年   10篇
  1997年   13篇
  1996年   3篇
  1995年   6篇
  1994年   8篇
  1993年   3篇
  1992年   2篇
  1991年   16篇
  1990年   10篇
  1989年   9篇
  1988年   6篇
  1987年   5篇
  1986年   3篇
  1985年   3篇
  1984年   2篇
  1983年   4篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1979年   4篇
  1973年   1篇
  1972年   1篇
排序方式: 共有1687条查询结果,搜索用时 15 毫秒
101.
The aim of this study was to describe a novel device that has been designed to facilitate anterior segment and novice surgeons to perform extraocular needle-guided haptic insertion technique (X-NIT) for scleral fixation intraocular lens surgery (SFIOL). We performed SFIOL surgery using X-NIT device in 21 eyes of 21 patients. The mean preoperative best-corrected visual acuity (BCVA) was 0.5 ± 0.2 logarithm of minimum angle of resolution (log MAR), which improved by one or more lines postoperatively in all eyes. There were no intraoperative complications. Postoperatively, we noted minimal corneal edema in one patient and dispersed vitreous hemorrhage in one patient. The sharpness and angulation of the needle and the haptic holding ability of silicone stopper were found to be satisfactory. The X-NIT device may potentially improve the safety of SFIOL procedures by minimizing intraocular maneuvers.  相似文献   
102.
Introduction: The major challenge of first pass metabolism in oral drug delivery can be surmounted by directing delivery toward intestinal lymphatic system (ILS). ILS circumvents the liver and transports drug directly into systemic circulation via thoracic duct. Lipid and polymeric nanoparticles are transported into ILS through lacteal and Peyer’s patches. Moreover, surface modification of nanoparticles with ligand which is specific for Peyer’s patches enhances the uptake of drugs into ILS. Bioavailability enhancement by lymphatic uptake is an advantageous approach adopted by scientists today. Therefore, it is important to understand clear insight of ILS in targeted drug delivery and challenges involved in it.

Areas covered: Current review includes an overview of ILS, factors governing lymphatic transport of nanoparticles and absorption mechanism of lipid and polymeric nanoparticles into ILS. Various ligands used to target Peyer’s patch and their conjugation strategies to nanoparticles are explained in detail. In vitro and in vivo models used to assess intestinal lymphatic transport of molecules are discussed further.

Expert opinion: Although ILS offers a versatile pathway for nanotechnology based targeted drug delivery, extensive investigations on validation of the lymphatic transport models and on the strategies for gastric protection of targeted nanocarriers have to be perceived in for excellent performance of ILS in oral drug delivery.  相似文献   

103.
A series of 2‐(substituted phenyl/benzyl‐amino)‐6‐(4‐chlorophenyl)‐5‐(methoxycarbonyl)‐4‐methyl‐3,6‐dihydropyrimidin‐1‐ium chlorides 7–13 and 15 was synthesized in their hydrochloride salt form. The title compounds were characterized by FT‐IR, NMR (1H and 13C) and elemental analysis. They were evaluated for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv, multidrug resistance tuberculosis and extensively drug resistance tuberculosis by agar diffusion method and tested for the cytotoxic action on peripheral blood mononuclear cells by MTT assay. Among all the tested compounds in the series, compounds 7 and 11 emerged as promising antitubercular agents at 16 μg/mL against multidrug resistance tuberculosis and over 64 μg/mL against extensively drug resistance tuberculosis. The conformational features and supramolecular assembly of the promising compounds 7 and 11 were determined by single crystal X‐ray study.  相似文献   
104.
105.
106.
107.
Novel diallyl and dibenzylthiosemicarbazones were prepared by three-step reactions. The compounds were tested for their in vitro activity against Mycobacterium tuberculosis H37Rv (MTB) and multi-drug-resistant Mycobacterium tuberculosis (MDR-TB). Most of the compounds showed excellent activity toward MDR-TB. Among the thirty compounds (4,5ao) tested N,N-dibenzyl-2-((5-nitrofuran-2-yl)methylene)hydrazinecarbothioamide (5g) was found to be the most potent compound MICs of 0.55 and 0.12 μM against MTB and MDR-TB.  相似文献   
108.
Lysine ?‐aminotransferase (LAT) is a protein involved in lysine catabolism, and it plays a significant role during the persistent/latent phase of Mycobacterium tuberculosis (MTB), as observed by its up‐regulation by ~40‐fold during this stage. We have used the crystal structure of MTB LAT in external aldimine form in complex with its substrate lysine as a template to design and identify seven lead compounds with IC50 ranging from 18.06 to > 90 μm . We have synthesized 21 compounds based on the identified lead, and compound 21 [2,2′‐oxybis(N′‐(4‐fluorobenzylidene)acetohydrazide)] was found to be the most active with MTB LAT IC50 of 0.81 ± 0.03 μm . Compound 21 also showed a 2.3 log reduction in the nutrient‐starved MTB model and was more potent than standard isoniazid and rifampicin at the same dose level of 10 μg/mL.  相似文献   
109.
Purpose: The purpose of this study is to determine racial and ethnic disparities with the adherence to inhaled corticosteroids (ICSs) in adults with persistent asthma, and their association with healthcare expenditures.

Methods: A retrospective, cross-sectional study using the Medical Expenditure Panel Survey (MEPS) 2013–2014 data included patients ≥18 years with persistent asthma. Median medication possession ratio (MPR) was used to dichotomize adherence levels. Multivariate regression analysis was conducted to ascertain the association between adherence and race/ethnicity. Total expenditures and association with adherence were analyzed using a generalized linear model with a log link function and gamma distribution. Unadjusted expenditures were compared after bootstrapping.

Results: The average MPR of ICSs for the sample of 277 patients was 0.34. The average MPR level was 0.33 among whites, 0.37 among African-Americans and 0.35 among other minorities. The average MPR was 0.30 among Hispanics, and 0.35 among non-Hispanics. African-Americans were less likely to be adherent than whites (OR 0.95). Hispanics were less likely to be adherent (OR 0.4; CI 0.206–0.777). Higher adherence was associated with significantly higher total health expenditure than lower adherence ($19,223 vs. $12,840 respectively, p?<?.0001). African-Americans had slightly higher total expenditure compared to whites; however, other minorities had significantly lower health expenditures compared to whites (p?=?.01). Non-Hispanics spent significantly less on healthcare compared to Hispanics (p?=?.04).

Conclusions: Valuable insight into the economic cost of the disparities as they relate to persistent asthma provides further evidence of possible ethnic inequities that warrant addressing.  相似文献   
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