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   17835篇
  免费   1321篇
  国内免费   454篇
耳鼻咽喉   101篇
儿科学   571篇
妇产科学   160篇
基础医学   1247篇
口腔科学   300篇
临床医学   1373篇
内科学   1699篇
皮肤病学   267篇
神经病学   1311篇
特种医学   581篇
外国民族医学   5篇
外科学   993篇
综合类   2149篇
现状与发展   3篇
一般理论   2篇
预防医学   2100篇
眼科学   311篇
药学   3867篇
  20篇
中国医学   1295篇
肿瘤学   1255篇
  2024年   43篇
  2023年   241篇
  2022年   400篇
  2021年   511篇
  2020年   587篇
  2019年   527篇
  2018年   506篇
  2017年   609篇
  2016年   651篇
  2015年   584篇
  2014年   1118篇
  2013年   1517篇
  2012年   937篇
  2011年   947篇
  2010年   713篇
  2009年   764篇
  2008年   786篇
  2007年   790篇
  2006年   699篇
  2005年   635篇
  2004年   542篇
  2003年   532篇
  2002年   403篇
  2001年   330篇
  2000年   287篇
  1999年   239篇
  1998年   253篇
  1997年   253篇
  1996年   218篇
  1995年   193篇
  1994年   191篇
  1993年   178篇
  1992年   197篇
  1991年   190篇
  1990年   172篇
  1989年   164篇
  1988年   169篇
  1987年   167篇
  1986年   152篇
  1985年   170篇
  1984年   181篇
  1983年   100篇
  1982年   145篇
  1981年   97篇
  1980年   101篇
  1979年   93篇
  1978年   67篇
  1977年   69篇
  1976年   58篇
  1975年   39篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The aim of this study was to develop films based on β–glucans in association with pomegranate juice for its potential in metabolic disorders such as diabetes due to plenty of bioactive compounds from the film composition. Initially, a Box-Behnken design was generated by varying the level of β–glucan content (0.5, 1, 1.5 g), sodium alginate (0.2, 0.4, 0.6 g) and pomegranate juice (10, 20, 30 mL) for development of films. Subsequently, glycerin was added as 25% of the total dry matter. The optimization of the films prepared by the solvent casting method was conducted based on the different responses such as: water vapor transmission rate (WVTR), water vapor permeability (WVP), thickness, density, moisture content, solubility, film opacity and color. The water activity profile and FT–IR analysis were performed in all tests. The model was used to determine the optimal experimental values considering that the optimal film will make a sustained contribution to diabetes. The optimal values of the film sample made of β–glucans, sodium alginate, pomegranate juice and glycerin make it befitting for packaging dry powdered pharmaceuticals. Finally, antimicrobial activity against Gram-negative and Gram-positive bacteria, UV barrier properties and microcrack and pore detections through SEM were also investigated for the optimal film sample.  相似文献   
102.
The unregulated use of acetaminophen (APAP), an antipyretic and analgesic drug, harms hepatocytes and kidney cells, leading to liver failure and acute kidney injury. Herein, we investigate whether APAP damages macrophages in the immune system by observing its effects on macrophage proliferation and apoptosis. Using proteomics, we analyzed the effects of APAP on macrophage protein expression profiles and evaluated whether polydatin, the active ingredient in grapes and wine, can repair the damaged cells. The results showed that APAP alters the morphology and physiological processes of macrophages, inhibits macrophage proliferation, and promotes apoptosis. We observed 528 differentially expressed proteins when 500 µg/mL APAP was administered to the cells. These proteins are involved in biological processes including cell division, apoptosis, and acute phase response. Overall, our findings demonstrate that APAP harms the immune system by damaging macrophages and that polydatin can repair this damage.  相似文献   
103.
目的观察强心化瘀方对慢性心力衰竭的临床疗效。方法将106例慢性心力衰竭患者随机分为治疗组(A组,应用强心化瘀方治疗,69例)和对照组(B组,应用西医综合治疗,37例),比较两组总有效率、心功能改善状况、心力衰竭常见症状及体征改善率。结果 A组总有效率高于B组(94.20% v s .72.98%)( P<0.05)。治疗后,A组气短、心悸、疲劳乏力、咳嗽咳痰和紫绀的改善率均高于B组(91.30% vs .72.97%、81.03% vs .48.28%、65.57% vs .15.63%、77.14% vs .33.33%和75.56% v s .24.13%)( P<0.05)。治疗后,A组心功能Ⅰ级患者所占比例多于B组( P<0.05)。结论强心化瘀方治疗慢性心力衰竭疗效确切,较常规西药疗效好。  相似文献   
104.
105.
槲皮素对培养人视网膜色素上皮细胞增生及DNA合成的影响   总被引:3,自引:0,他引:3  
目的研究槲皮素(quercetin, QUE)对培养人视网膜色素上皮(retinal pigment epithelium, RPE)细胞增生和DNA合成以及对表皮生长因子(epidermal growth factor, EGF)促RPE细胞增生和DNA合成作用的影响。方法用细胞计数和3H-胸腺嘧啶核苷(3H-thymidine, 3H-TdR)掺入方法,观察不同浓度(200、100、50、1μmol/L)的QUE和最大浓度的QUE(200μmol/L)在不同作用时间(24-168小时),分别单独或与EGF共同作用时,对RPE细胞增生及DNA合成的影响,排除着色的死细胞,用活细胞计数法判断药物的细胞毒性作用。结果QUE 200μmol/L具有最强的抑制效应,48小时时抑制效应已明显出现,96小时时抑制达到高峰。与QUE单独作用相比,QUE对EGF的促RPE细胞增生效应能产生更强的抑制。QUE无细胞毒性作用,各实验组细胞活力均在85.00%以上。结论QUE以剂量依赖和时间依赖的方式抑制RPE细胞的增生,尤其是由EGF刺激的增生,并且对培养的RPE细胞无细胞毒作用。(中华眼底病杂志,1999,15:27-29)  相似文献   
106.
通关藤化学成分和药理作用研究进展   总被引:6,自引:0,他引:6  
通关藤为萝藦科牛奶菜属植物通关藤的藤茎,其主要化学成分为C21甾体化合物,尚含有三萜、有机酸、甾醇、多糖等化合物.研究表明,其主要的药理作用为抗肿瘤,降压,平喘等.本文就近年来通关藤的化学成分和药理作用的研究进展作一综述,为其进一步的开发利用提供参考.  相似文献   
107.
附子毒-效关系探析   总被引:2,自引:0,他引:2  
李琳  平静 《河南中医》2015,35(1):171-172
应用附子要以"得附子之益,去附子之损"为原则,正所谓"正有毒以祛毒,非无毒以治有毒也"。附子之毒与效密不可分,是以毒攻毒治法的具体体现,辨证地看待附子的毒-效关系,从而对今后附子的临床合理应用提供一定的借鉴。  相似文献   
108.
The effect of radiotherapy during immunotherapy on immune-related adverse events (irAEs) is not fully understood. We herein report a 74-year-old woman diagnosed with lung adenocarcinoma with programmed death ligand 1 expression ≥50% and treated with pembrolizumab. She developed fatal immune thrombocytopenia associated with pembrolizumab immediately following radiotherapy. A flow cytometry analysis of peripheral blood detected an increased expression of programmed death-1 (PD-1) and Ki-67 in CD4 and CD8 T cells after radiotherapy, compared with pre-irradiation measurements. This case suggests that radiotherapy may evoke irAEs during treatment with anti-PD-1 antibodies, which physicians should consider when using radiotherapy in patients treated with these drugs.  相似文献   
109.
The Coronavirus Disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome-coronavirus-2, has claimed 5,587,549 lives worldwide as of January 20, 2022. Fortunately, large-scale vaccination can mitigate the impact of COVID-19 by making the disease milder and less common. Although 75.2% of the United States population has received at least 1 dose of a COVID-19 vaccines thus far, concerns regarding vaccine side effects have contributed to vaccine hesitancy. Furthermore, nearly 50% of adults in the United States are concerned not only about side effects, but about their downstream impact, including missed work.The goal of this cross-sectional study was to investigate the effect of messenger RNA vaccine adverse effects on the propensity to miss work among employees associated with a single, large academic health center.Using Qualtrics, all employees, including faculty, staff, and trainees, of 5 large departments were surveyed to determine whether they received the COVID-19 vaccine and which type, and any symptoms they experienced after receipt of either vaccine dose. We hypothesized that vaccine recipients would be more likely to miss work or feel sick enough to miss work following the second dose.Thirty-seven percent of respondents experienced events severe enough that they needed to miss work from either of the doses, with the majority (27.8%) related to the second dose. These findings are consistent with and expand on the results from the phase 3 trials for Pfizer-BionTech and Moderna, which showed that vaccine side effects were more common after the second dose than after the first dose. Our statistically significant finding was more common among Asians, women, trainees/house staff, and nonphysician clinical employees.With an increasing number of individuals taking the vaccine, employers will need to account for the impact of adverse effects on their employees’ ability to work. These findings will further help organizations better plan for staffing as vaccinations increase to mitigate the spread of COVID-19.  相似文献   
110.
Research on the effects of glyphosate and seed germination spans 30 years. Despite several studies reporting detrimental effects of the herbicide on seedling germination and growth, glyphosate is still being registered for use as a weed killer and preharvest desiccant. Its nonselective nature and low chance of species developing resistance has lead to the development of genetically modified crops tolerant to the herbicide which also raises concerns about increased reliance on herbicide use, and subtle ecological impact.This paper presents the result of a literature review on past studies mostly, on crop species, and the results of a new experiment performed with emphasis on noncrop species. The new experimental part attempted to determine whether glyphosate (Roundup®) would have an effect on the germination and growth of the F1 generation of seeds produced by plants sprayed with the herbicide. It was designed to mirror spray drift which might affect noncrop plants in nontarget drift zones. Of the 11 species tested using treatments of 0% (control), 1%, 10% or 100% of a 890 g a.i./ha label rate solution sprayed near seed maturity, seven showed a significant effect of the glyphosate treatment on germination and/or growth characteristics.Results of this experiment together with several previous studies reviewed in this paper suggest that there are significant effects to keep in mind when using herbicides such as glyphosate as severe ecological changes could occur.  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