全文获取类型
收费全文 | 7854篇 |
免费 | 861篇 |
国内免费 | 34篇 |
专业分类
耳鼻咽喉 | 180篇 |
儿科学 | 480篇 |
妇产科学 | 247篇 |
基础医学 | 745篇 |
口腔科学 | 569篇 |
临床医学 | 855篇 |
内科学 | 1510篇 |
皮肤病学 | 181篇 |
神经病学 | 517篇 |
特种医学 | 353篇 |
外科学 | 1655篇 |
综合类 | 186篇 |
一般理论 | 1篇 |
预防医学 | 346篇 |
眼科学 | 204篇 |
药学 | 427篇 |
中国医学 | 13篇 |
肿瘤学 | 280篇 |
出版年
2024年 | 15篇 |
2023年 | 166篇 |
2022年 | 118篇 |
2021年 | 281篇 |
2020年 | 203篇 |
2019年 | 225篇 |
2018年 | 457篇 |
2017年 | 355篇 |
2016年 | 465篇 |
2015年 | 459篇 |
2014年 | 490篇 |
2013年 | 939篇 |
2012年 | 388篇 |
2011年 | 385篇 |
2010年 | 526篇 |
2009年 | 265篇 |
2008年 | 160篇 |
2007年 | 74篇 |
2006年 | 249篇 |
2005年 | 165篇 |
2004年 | 79篇 |
2003年 | 68篇 |
2002年 | 90篇 |
2001年 | 157篇 |
2000年 | 123篇 |
1999年 | 169篇 |
1998年 | 173篇 |
1997年 | 138篇 |
1996年 | 171篇 |
1995年 | 99篇 |
1994年 | 133篇 |
1993年 | 96篇 |
1992年 | 64篇 |
1991年 | 61篇 |
1990年 | 51篇 |
1989年 | 40篇 |
1988年 | 48篇 |
1987年 | 35篇 |
1986年 | 37篇 |
1985年 | 37篇 |
1984年 | 39篇 |
1983年 | 31篇 |
1982年 | 34篇 |
1981年 | 35篇 |
1980年 | 32篇 |
1979年 | 22篇 |
1977年 | 14篇 |
1976年 | 16篇 |
1975年 | 13篇 |
1930年 | 13篇 |
排序方式: 共有8749条查询结果,搜索用时 15 毫秒
91.
目的: 探讨丹参酮ⅡA磺酸钠(STS)对大气细颗粒物(PM2.5)诱导的大鼠肺部损伤的保护作用及可能机制。方法: 24只清洁级雄性SD大鼠,随机分为4组,每组6只,分别为对照组(生理盐水)、PM2.5染毒组(模型组)、丹参酮ⅡA磺酸钠组(STS组)、地塞米松组(阳性对照)。采用气管滴注PM2.5悬液染毒,除对照组外,其余3组染毒剂量均为5.4 mg/kg,每3 d滴注1次,共10次,于染毒第1天起STS组和地塞米松组分别以浓度15 mg/kg和0.5 mg/kg腹腔注射,每天1次,持续28 d。末次染毒后24 h采用整体体积描记法(WBP)检测大鼠呼吸频率(f值)和被迫呼吸间隙(Penh);末次染毒后2 d,经腹主动脉采血2 mL,流式细胞术检测外周血淋巴细胞亚群;处死大鼠后灌洗左肺,收集肺泡灌洗液5 mL,ELISA法测定肺泡灌洗液中白细胞介素-1β(IL-1β)、肿瘤坏死因子-α(TNF-α)和白细胞介素6(IL-6)含量;Western blot检测肺组织核因子κB (NF-κB)蛋白表达。结果: 与对照组相比,模型组呼吸f值和Penh值均明显升高(P<0.01);CD4+细胞百分率和CD4+/CD8+比值降低(P<0.05);肺泡灌洗液中IL-1β、TNF-α和IL-6浓度升高(P<0.01);肺细胞浆中P65含量降低而胞核中p-P65含量升高(P<0.01)。与模型组相比,STS组f值和Penh值均降低(P<0.05或P<0.01);CD4+细胞百分率和CD4+/CD8+比值均升高(P<0.01或P<0.05);IL-1β、TNF-α、IL-6浓度降低(P<0.01或P<0.05);细胞浆中P65含量升高而胞核中p-P65含量降低(P<0.01)。结论: STS对PM2.5诱导的大鼠肺部炎症有抑制作用,并具有调节肺功能和免疫功能的作用。 相似文献
92.
目的:探讨M1型巨噬细胞源外泌体对卵泡膜细胞活力的影响及其作用机制。方法:采用脂多糖(LPS)处理Raw264.7小鼠巨噬细胞,构建M1型巨噬细胞模型及巨噬细胞-卵泡膜细胞共培养体系。超速离心法分离巨噬细胞分泌的外泌体;通过电镜、Western blot和纳米流式检测仪鉴定外泌体。体外分离培养小鼠卵泡膜细胞,与PKH67荧光标记的外泌体共孵育,观察卵泡膜细胞摄取外泌体的情况。CCK-8法检测细胞活力,流式细胞术分析细胞周期分布,q PCR及Western blot检测细胞周期蛋白依赖性激酶抑制因子1B(CDKN1B)的表达。结果:在巨噬细胞-卵泡膜细胞共培养体系中,LPS诱导的M1型巨噬细胞通过外泌体增强卵泡膜细胞活力。电镜、Western blot及纳米流式检测结果显示,巨噬细胞源外泌体被成功分离。PKH67标记的外泌体与卵泡膜细胞共孵育实验证实卵泡膜细胞能摄取大量巨噬细胞源外泌体。这些外泌体可增强卵泡膜细胞的活力,使卵泡膜细胞G0/G1期比例下降,S期比例升高,且卵泡膜细胞CDKN1B的m RNA及蛋白相对表达量均明显低于对照组。结论:卵... 相似文献
93.
Introduction: Chronic progressiveexternal ophthalmoplegia is characterisedby limitation of ocular motility in alldirections of gaze and ptosis.Innervational or myogenic factors wereclaimed to be responsible for thismotility disorder. The aim of thisstudy was toinvestigate the extraocular muscles inCPEO with computerized tomography in an attemptto distinguish extraocular musclemorphology caused by this disorderfrom that occurring in normal individuals.Methods: Eighteen orbits from 9patients diagnosed with CPEOwere included in the study. Axialand coronal scans were obtained for CTevaluation of extraocular muscles and thedimensions of extraocular muscles were measured.The control group consisted of40 orbits belonging to 20 individuals and,the results were compared with a student'st test.Results: The thickness (the verticaldimension of vertical recti and thehorizontal dimension of horizontal recti)of all rectus muscles wassignificantly decreased in comparison with the controlgroup, whereas the width (the horizontal dimensionof vertical recti and the verticaldimension of horizontal recti) was similar inboth the diseased and normal orbits.In all the rectus musclesof the diseased orbits,the normal fusiform shape was lost and the muscles appeared asthin bands.Discussion: The differentiation ofCPEO from other myogenic and neurogenicdisorders may present difficulty,and a cluster of criteria are required fora final diagnosis. CT has provento be a valuable tool in assessing extraocularmuscles [1, 2]. In this study, an extremeatrophy of all rectus muscles wasdemonstrated by means of CT. This diagnostic method mayconsequently contribute to a properdiagnosis of CPEO. 相似文献
94.
Janet Hoogstraate Lars I. Andersson Odd-Geir Berge Bror Jonzon Göran Öjteg 《Inflammopharmacology》2003,11(4-6):423-428
The clinical utility of non-selective non-steroidal anti-inflammatory drugs (NSAIDs) for pain relief is tempered by their propensity to cause gastrointestinal toxicity. Cyclooxygenase (COX)-inhibiting nitric oxide donators (CINODs) are a new class of drugs designed to provide analgesic efficacy through COX inhibition and gastrointestinal safety through the protective effects of controlled nitric oxide donation. Pre-clinical studies assessing the pharmacology, efficacy and gastrointestinal safety of AZD3582 [4-(nitrooxy)butyl-(2S)-2-(6-methoxy-2-naphthyl)propanoate] support this concept. Based on these studies, AZD3582 was the first CINOD to enter clinical development for the treatment of acute and chronic pain. The potential clinical utility of this new class is illustrated by a study of AZD3582 in healthy volunteers in which it caused significantly less acute gastrointestinal toxicity than an equimolar dose of naproxen. The results of the animal studies and the initial clinical study warrant long-term tolerability studies of AZD3582 along with evaluation of its anti-inflammatory and analgesic effects in humans. 相似文献
95.
Miriş Dikmen Yusuf Öztürk Gianni Sagratini Massimo Ricciutelli Sauro Vittori Filippo Maggi 《Phytotherapy research : PTR》2011,25(2):208-214
For centuries, Hypericum perforatum has been used in folk medicine to treat wounds. In the present study, the wound healing activities of extracts of H. perforatum ssp. perforatum (HPP) and H. perforatum ssp. veronense (HPV) were evaluated by comparing with a titrated extract of Centella asiatica (TECA) on NIH3T3 fibroblasts. The cells were incubated with the extracts. Using microscopical methods by staining cells, mitotic ability, morphological changes and collagen production in the fibroblasts were evaluated as parameters to approach possible wound repair mechanism(s). The wound healing activity caused an increase in the percentage of polygonal fibroblasts and in collagen granule numbers in fibroblasts of HPP and HPV. At 1 µg/mL, HPP caused a greater increase in mitotic cell numbers than HPV. The most increases in polygonal cell numbers were observed with HPV at 1 and 10 µg/mL. The number of collagen granules was increased with 1 µg/mL HPV being higher than HPP. As an indication of cytotoxic effects, round cells in response to HPV and HPP extracts, were found to be increased in concentrations higher than 10–50 µg/mL. The results indicated that the two subspecies of H. perforatum have different wound healing profiles as a result of the fibroblast migration and stimulation of collagen synthesis. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
96.
Effects of pesticides on human peripheral lymphocytes in vitro: induction of DNA damage 总被引:6,自引:0,他引:6
Because of the widespread use of pesticides for domestic and industrial applications the evaluation of their genotoxic effects is of major concern to public health. Although various experimental data have provided evidence that pesticides can possess genotoxic properties in animals and in in vitro test systems after acute and chronic exposure, the information on the genotoxic effects of some of pesticides is limited and inconsistent. In the present study, the genotoxic potential of commonly used pesticides (i.e., dimethoate and methyl parathion from the organophosphate class, propoxur and pirimicarb from carbamates, and cypermethrin and permethrin from pyrethroids) have been evaluated. The genotoxic effects of these substances were examined using the single cell gel electrophoresis (comet) assay in freshly isolated human peripheral lymphocytes. The cells were incubated with 10, 50, 100 and 200 µg/ml concentrations of the test substances for 0.5 h at 37°C and DNA damage was compared with that obtained in lymphocytes from the same donor not treated with substances. Hydrogen peroxide, 100 µM, was used as a positive control. Within the concentration ranges studied, no significant cytotoxic effects were observed. Dimethoate and methyl parathion at 100 and 200 µg/ml; propoxur at 50, 100 and 200 µg/ml, and pirimicarb, cypermethrin and permethrin at 200 µg/ml significantly increased DNA damage in human lymphocytes. 相似文献
97.
Oya Soylu Karapinar Neslihan Pinar Oğuzhan Özcan Tümay Özgür Kenan Dolapçıoğlu 《Gynecological endocrinology》2017,33(8):653-659
To determine whether the possible oxidative effect of methotrexate (Mtx) on ovary and to evaluate the effectiveness of alpha lipoic acid (ALA), which may be useful in many oxidative stress models.Thirty-two female Wistar-albino rats were randomly divided into four groups; control group, alpha lipoic acid group (ALA 100?mg/kg, 10?days), multiple dose Mtx group (Mtx 1?mg/kg 1, 3, 5, 7?days) and Mtx and ALA group (Mtx 1?mg/kg 1, 3, 5, 7?days and ALA 100?mg/kg, 10?days). Serum total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI), tumor necrosis factor-alpha (TNF-α), tissue malondialdehyde (MDA) and activities of glutathione peroxidase (GSH-Px) and catalase (CAT) and anti-Mullerian hormone (AMH) and total ovarian follicle count were evaluated.Mtx administration caused a significant decrease in TAS, a significant increase in TOS and OSI, a significant increase in MDA levels and a decrease in GSH-Px and CAT activity. Moreover the proinflammatory cytokine (TNF-α) was increased in the Mtx group. And AMH values and total follicle count were significantly decreased in Mtx group. However, ALA treatment reversed biochemical results and AMH levels and total follicle count.Alpha lipoic acid ameliorates methotrexate induced oxidative damage of ovarian in rats. 相似文献
98.
Mehmet Tetikoğlu Serdar Aktas Hacı Murat Sagdık Sıla Tasdemir Yigitoglu Fatih Özcura 《Seminars in ophthalmology》2017,32(5):651-654
Aim: To evaluate the effect of the platelet indices on the stage of diabetic retinopathy (DR) and diabetic macular edema (DME). Methods: In this retrospective study, the mean platelet valume (MPV), Plateletcrit (PCT), platelet (PLT), and platelet distribution width (PDW) of 199 diabetic patients and 76 healthy subjects were enrolled. The participants were divided into four groups. The first group was healthy control; the second group consisted of diabetic patients without DR; the third group was nonproliferative DR (NPDR); and the fourth group was proliferative DR (PDR). Results: Significant differences were found only in MPV and PCT values between patients with diabetes and healthy participants (8.6±0.96 fL vs 8.32±0.9 fL, P=0.011, 0.216± 0.58 vs 0.202±0.52, P=0.038). Comparing the groups, a statistically significant difference in MPV values was found between groups 4 and 1 (8.91±.7 fL vs 8.32±0.9 fL P=0.001) and between groups 4 and 3 (8.91±.7 fL vs 8.42±0.9 fL P=0.014). The MPV values of patients with DME were significantly higher than those of diabetic patients without DME (8.87±0.80 fL vs 8.45±0.97 fL). Conclusion: High MPV values may be an important risk factor for the development of PDR and DME in patients with diabetic retinopathy. 相似文献
99.
目的调查肺癌患者在围手术期不同时间点的症状群和生活质量,并分析两者的相关性,为临床护士动态管理其症状群及改善其生活质量提供依据。方法便利选取2019年1月—9月就诊于合肥市某三级甲等医院胸外科行手术治疗的217例肺癌患者为调查对象。在患者入院当天、术后2~4 d和术后1个月,采用一般资料调查表、中文版安德森症状评估量表-肺癌模块及肺癌患者生活质量评估量表进行调查。结果入院当天肺癌患者存在呼吸道症状群、疼痛-疲乏-睡眠障碍症状群、心理情感症状群及神经系统症状群,共4个症状群;术后2~4 d和术后1个月患者增加了消化道症状群,共5个症状群,各时间点群内症状组成不同。肺癌患者围手术期不同时间点生活质量总分及各维度得分(除社会与家庭状况维度)比较,差异有统计学意义(P<0.001)。入院当天,呼吸道症状群严重程度得分与患者生活质量总分及各维度得分均呈负相关(P<0.01);术后2~4 d,呼吸道及疼痛-疲乏-睡眠障碍症状群严重程度得分均与患者生活质量总分呈负相关(P<0.05);术后1个月,5个症状群严重程度得分均与患者生活质量总分呈负相关(P<0.01)。结论肺癌患者... 相似文献
100.
高迁移率族蛋白B1(high-mobility group box 1,HMGB1)是一种普遍存在于真核细胞中的非组核蛋白。在细胞核内的HMGB1主要参与DNA修复、转录、维持端粒酶的活性以及染色体稳定。释放至细胞核外的HMGB1在细胞的增殖、炎症、血管生成、免疫耐受、免疫逃逸中发挥促肿瘤作用;但又能活化和募集免疫细胞至肿瘤微环境中,诱导肿瘤细胞发生免疫原性细胞死亡,从而发挥抗肿瘤作用。HMGB1在多种肿瘤中异常表达,参与了肿瘤的发生、发展和转移,故推测它可能同时发挥促肿瘤和抗肿瘤的双重作用。 相似文献