全文获取类型
收费全文 | 180598篇 |
免费 | 17583篇 |
国内免费 | 8801篇 |
专业分类
耳鼻咽喉 | 2526篇 |
儿科学 | 3918篇 |
妇产科学 | 2018篇 |
基础医学 | 33168篇 |
口腔科学 | 6261篇 |
临床医学 | 14591篇 |
内科学 | 23835篇 |
皮肤病学 | 4594篇 |
神经病学 | 11011篇 |
特种医学 | 4047篇 |
外国民族医学 | 121篇 |
外科学 | 16878篇 |
综合类 | 28666篇 |
现状与发展 | 49篇 |
一般理论 | 2篇 |
预防医学 | 4542篇 |
眼科学 | 3788篇 |
药学 | 13626篇 |
31篇 | |
中国医学 | 5459篇 |
肿瘤学 | 27851篇 |
出版年
2024年 | 142篇 |
2023年 | 2489篇 |
2022年 | 3204篇 |
2021年 | 6104篇 |
2020年 | 5918篇 |
2019年 | 5674篇 |
2018年 | 5937篇 |
2017年 | 6343篇 |
2016年 | 6736篇 |
2015年 | 7690篇 |
2014年 | 11493篇 |
2013年 | 12624篇 |
2012年 | 10688篇 |
2011年 | 12106篇 |
2010年 | 10086篇 |
2009年 | 9553篇 |
2008年 | 9932篇 |
2007年 | 10095篇 |
2006年 | 9137篇 |
2005年 | 8349篇 |
2004年 | 7296篇 |
2003年 | 6210篇 |
2002年 | 5036篇 |
2001年 | 4292篇 |
2000年 | 3526篇 |
1999年 | 3040篇 |
1998年 | 2493篇 |
1997年 | 2439篇 |
1996年 | 2094篇 |
1995年 | 2118篇 |
1994年 | 1878篇 |
1993年 | 1572篇 |
1992年 | 1274篇 |
1991年 | 1200篇 |
1990年 | 943篇 |
1989年 | 878篇 |
1988年 | 816篇 |
1987年 | 653篇 |
1986年 | 608篇 |
1985年 | 809篇 |
1984年 | 716篇 |
1983年 | 494篇 |
1982年 | 548篇 |
1981年 | 434篇 |
1980年 | 387篇 |
1979年 | 278篇 |
1978年 | 195篇 |
1977年 | 154篇 |
1976年 | 118篇 |
1975年 | 41篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
《Journal of vascular and interventional radiology : JVIR》2022,33(8):964-971.e2
PurposeTo assess the cost effectiveness of microwave ablation (MWA) and stereotactic body radiotherapy (SBRT) for patients with inoperable stage I non–small cell lung cancer (NSCLC).Materials and MethodsA literature search was performed in MEDLINE with broad search clusters. A decision-analytic model was constructed over a 5-year period. The model incorporated treatment-related complications and long-term recurrence. All clinical parameters were derived from the literature with preference to long-term prospective trials. A healthcare payers’ perspective was adopted. Outcomes were measured in quality-adjusted life years (QALYs) extracted from prior studies and U.S. dollars from Medicare reimbursements and prior studies. Base case calculations, probabilistic sensitivity analysis with 10,000 Monte Carlo simulations, and multiple 1- and 2-way sensitivity analyses were performed.ResultsMWA yielded a health benefit of 2.31 QALYs at a cost of $195,331, whereas SBRT yielded a health benefit of 2.33 QALYs at a cost of $225,271. The incremental cost-effectiveness ratio was $1,480,597/QALY, indicating that MWA is the more cost-effective strategy. The conclusion remains unchanged in probabilistic sensitivity analysis with MWA being the optimal cost strategy in 99.84% simulations. One-way sensitivity analyses revealed that MWA remains cost effective when its annual recurrence risk is <18.4% averaged over 5 years, when the SBRT annual recurrence risk is >1.44% averaged over 5 years, or when MWA is at least $7,500 cheaper than SBRT.ConclusionsMWA appears to be more cost effective than SBRT for patients with inoperable stage I NSCLC. 相似文献
42.
《Journal of thoracic oncology》2022,17(3):362-387
The 2021 WHO Classification of Thoracic Tumours was published earlier this year, with classification of lung tumors being one of the chapters. The principles remain those of using morphology first, supported by immunohistochemistry, and then molecular techniques. In 2015, there was particular emphasis on using immunohistochemistry to make classification more accurate. In 2021, there is greater emphasis throughout the book on advances in molecular pathology across all tumor types. Major features within this edition are (1) broader emphasis on genetic testing than in the 2015 WHO Classification; (2) a section entirely dedicated to the classification of small diagnostic samples; (3) continued recommendation to document percentages of histologic patterns in invasive nonmucinous adenocarcinomas, with utilization of these features to apply a formal grading system, and using only invasive size for T-factor size determination in part lepidic nonmucinous lung adenocarcinomas as recommended by the eighth edition TNM classification; (4) recognition of spread through airspaces as a histologic feature with prognostic significance; (5) moving lymphoepithelial carcinoma to squamous cell carcinomas; (6) update on evolving concepts in lung neuroendocrine neoplasm classification; (7) recognition of bronchiolar adenoma/ciliated muconodular papillary tumor as a new entity within the adenoma subgroup; (8) recognition of thoracic SMARCA4-deficient undifferentiated tumor; and (9) inclusion of essential and desirable diagnostic criteria for each tumor. 相似文献
43.
44.
45.
目的 慢性牙周炎表现的病理性骨吸收非常常见,牙周膜干细胞(PDLSCs)的外泌体(Exo)对骨吸收的作用和影响尚不明确,本研究分析了该Exo蛋白组分对破骨细胞分化的影响。方法 分别从正畸前拔牙患者和慢性牙周炎患者的牙周膜组织中提取PDLSCs,通过流式细胞术检测表面标记物;通过差速离心分别提取2种细胞的Exo,即Exo-WT和Exo-CP,并通过Western blot、透射电子显微镜(TEM)、蛋白浓度检测、纳米粒径追踪检测Exo特征;通过蛋白质谱检测2种Exo的蛋白组分;通过酶联免疫吸附(ELISA)验证了差异表达蛋白肿瘤坏死因子α(TNF-α)、核因子κB受体活化因子配体(RANKL)、白细胞介素(IL)-1α、转化生长因子β(TGF-β)、骨形态发生蛋白2(BMP-2)表达水平;将10、100、1 000 μg·mL-1的Exo-CP或Exo-WT加入RAW264.7培养基中并于5 d时通过实时荧光定量聚合酶链反应(RT-qPCR)、Western blot、抗酒石酸酸性磷酸酶(TRAP)染色检测破骨分化相关指标表达情况;采用SPSS 24.0软件对实验数据进行统计学分析。结果 Exo-CP富集的差异表达蛋白主要与破骨细胞分化的TNF信号通路、核转录因子κB(NF-κB)信号通路相关;ELISA实验证实了Exo-CP中高表达TNF-α、RANKL、IL-1α,低表达TGF-β1、BMP-2(P<0.05);Exo-CP作用于RAW264.7,显著提高了细胞的破骨分化相关基因及蛋白的表达水平,TRAP染色可见分化的破骨细胞,且呈现浓度依赖性,100、1 000 μg·mL-1浓度Exo-CP对破骨细胞分化的促进作用显著高于10 μg·mL-1浓度组(P<0.05)。结论 慢性牙周炎的病理性骨吸收可能由炎性PDLSCs所分泌的Exo通过促进破骨细胞分化引起,Exo中主要的作用蛋白可能为RANKL和TNF-α,本研究为慢性牙周炎骨吸收的发病机制提供了新视角。 相似文献
46.
目的研究利用经聚乙烯亚胺(PEI)钝化的荧光碳点(CD)装载阿霉素(DOX)进行药物递送,旨在增加DOX对非小细胞肺癌的治疗作用,减少DOX的心肌毒性。 方法通过一步微波加热法将甘油和PEI的混合物制备成CD-PEI,并通过静电效应将DOX装载至CD-PEI。采用CCK8实验检测CD-PEI-DOX对非小细胞肺癌细胞A549的增殖能力的影响;Transwell实验评估CD-PEI-DOX对A549细胞迁移侵袭能力的影响;最后通过体内动物实验评估CD-PEI-DOX的心肌毒性以及对非小细胞肺癌皮下肿瘤生长的抑制效果。 结果体外细胞实验证实,对比单纯的DOX处理组,CD-PEI-DOX对非小细胞肺癌A549细胞增殖、迁移侵袭能力的抑制作用更为显著。体内实验证实,CD-PEI-DOX纳米复合物治疗组小鼠心肌细胞结构完整,并且能有效抑制小鼠皮下肺癌肿瘤的生长。 结论经PEI钝化的荧光碳点负载阿霉素能显著提高DOX对非小细胞肺癌的治疗效果,并减少DOX对心脏的毒性作用。运用CD-PEI纳米颗粒改善化疗药物递送的治疗方案取得了初步证实,这可为肺癌化学治疗提供新思路,具有广大的临床应用前景。 相似文献
47.
Evaluation of the Role of Merromoside from Ipomoea aquatica Forsskal Hydroalcoholic Extract in the Downregulation of ROS Species in Overcoming MDR in Breast Cancer 下载免费PDF全文
Sasikala MMohan SSwarnakumari SNagarajan A 《Asian Pacific journal of cancer prevention》2022,23(11):3657-3663
Purpose: The medicinal plant Ipomoea aquatica belonging to convulvulaceae family is an effective natural herb for treatment of various ailments and possesses effective anticancer activity. The aim of the work is to characterize a secondary metabolite merromoside (a resin glycoside) for anti-breast cancer activity through down regulation of ROS species. Methods: The Extract of the whole plant has been prepared by maceration method using 50%v/v ethanol in distilled water to get a hydroalcoholic extract. The phytochemical evaluation reveals that the active secondary metabolite was isolated by using column chromatographic technique. The isolated compound was evaluated for its anticancer properties through invitro method such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay on Michigan Cancer Foundation-7 Cell lines. The purity and structural characterization were done by high-performance thin layer chromatography, Fourier Transform Infrared Spectroscopy, Proton and13C Nuclear Magnetic Resonance spectroscopy and Liquid Chromatography–Mass Spectrometry. Results: The isolated compound (W04) from the derived extract showed Rf value of 0.79 that showed IC50 of 182.8μg/ml. The chemical structure of W04 has been confirmed as [4,5-dihydroxy-6-[5-hydroxy-2-methyl-4-(2-methylpropanoyloxy)-6-[(24,25,26-trihydroxy-5,23-dimethyl-9-oxo-19-pentyl-2,4,8,20,22-pentaoxatricyclo[19.2.2.13,7]hexacosan-6-yl)oxy]oxan-3-yl]oxy-2-methyloxan-3-yl] 2-methyl propanoate with the molecular weight of 979.15268. The isolated compound merromoside from hydroalcoholic extract of Ipomoea aquatica has been evaluated for anti-breast cancer properties. The down regulation of ROS species will prevent reverse signalling and angiogenesis. This indicates that merromoside will overcome MDR in breast cancer especially DOX-resistant. 相似文献
48.
49.
50.
《Journal of pediatric surgery》2023,58(9):1613-1617
BackgroundThe goal of this study was to characterize contemporary performance benchmarks and risk factors associated with negative appendectomy (NA) in children with suspected appendicitis.MethodsA multicenter retrospective cohort analysis of children undergoing appendectomy for suspected appendicitis was performed using data from the 2016–2021 NSQIP-Pediatric Appendectomy Targeted Public Use Files. Multivariable regression was used to evaluate the influence of year, age, sex, and WBC count on NA rate, and to generate rate estimates for NA based on different combinations of demographic characteristics and WBC profiles.Results100,322 patients were included from 140 hospitals. The overall NA rate was 2.4%, and rates decreased significantly during the study period (2016: 3.1% vs. 2021: 2.3%, p < 0.001). In adjusted analyses, the highest risk for NA was associated with a normal WBC (<9000/mm3; OR 5.31 [95% CI: 4.87–5.80]), followed by female sex (OR 1.55 [95% CI: 1.42–1.68]) and age <5 years (OR 1.64 [95% CI 1.39, 1.94]). Model-estimated risk for NA varied significantly across demographic and WBC strata, with a 14.4-fold range in rates between subgroups with the lowest and highest predicted risk (males 13–17 years with elevated WBC [1.1%] vs. females 3–4 years with normal WBC [15.8%]).ConclusionsContemporary NA rates have decreased over time, however NA risk remains high in children without a leukocytosis, particularly for girls and children <5 years of age. These data provide contemporary performance benchmarks for NA in children with suspected appendicitis and identify high-risk populations where further efforts to mitigate NA risk should be targeted.Level of EvidenceIII. 相似文献