全文获取类型
收费全文 | 973篇 |
免费 | 148篇 |
国内免费 | 42篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 12篇 |
妇产科学 | 2篇 |
基础医学 | 105篇 |
口腔科学 | 6篇 |
临床医学 | 80篇 |
内科学 | 90篇 |
皮肤病学 | 10篇 |
神经病学 | 48篇 |
特种医学 | 26篇 |
外国民族医学 | 1篇 |
外科学 | 145篇 |
综合类 | 233篇 |
现状与发展 | 1篇 |
预防医学 | 72篇 |
眼科学 | 3篇 |
药学 | 112篇 |
中国医学 | 111篇 |
肿瘤学 | 86篇 |
出版年
2024年 | 14篇 |
2023年 | 51篇 |
2022年 | 61篇 |
2021年 | 94篇 |
2020年 | 61篇 |
2019年 | 47篇 |
2018年 | 50篇 |
2017年 | 60篇 |
2016年 | 34篇 |
2015年 | 70篇 |
2014年 | 73篇 |
2013年 | 47篇 |
2012年 | 58篇 |
2011年 | 64篇 |
2010年 | 43篇 |
2009年 | 36篇 |
2008年 | 40篇 |
2007年 | 37篇 |
2006年 | 26篇 |
2005年 | 22篇 |
2004年 | 19篇 |
2003年 | 16篇 |
2002年 | 22篇 |
2001年 | 12篇 |
2000年 | 13篇 |
1999年 | 20篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1980年 | 1篇 |
排序方式: 共有1163条查询结果,搜索用时 31 毫秒
51.
Renzhong Luo Wenlong Liu Jie Wang Yanqiu Chen Changzhi Sun Lifeng Zhou Yan Li Li Deng 《European journal of pediatrics》2014,173(8):1033-1040
Sublingual immunotherapy (SLIT) is the only therapeutic option for allergic rhinitis (AR) that modifies the immunological process to an allergen, rather than treating symptoms simply. However, its regulatory mechanisms are largely unknown. B-cell-activating factor of the TNF family (BAFF) plays very important roles in the development, differentiation, and proliferation of B cells and T cells. The aim of this study was to identify the role of BAFF during SLIT in pediatric patients with AR. Seventy-two house dust mite (HDM)-sensitized pediatric patients with AR were enrolled in this study. Thirty-six pediatric patients received HDM allergen extract for SLIT and 36 pediatric patients received placebo. Serum and nasal aspirate of different time points during treatment was collected and used for enzyme-linked immunosorbent assay (ELISA) of BAFF and related cytokines, respectively. Peripheral blood mononuclear cells were collected and stimulated by HDM allergen with or without rhBAFF after 12 months of treatment. Our results showed that the expression of BAFF protein decreased during the SLIT treatment compared with that in the placebo group after 6 months of therapy, and this trend lasted for 12 months. The decreased BAFF expression was positively related to Th2 cytokines and increased IL-10 expression. BAFF was also related to local production of IgA. In vitro experiments showed that BAFF can promote Th2 cytokines and inhibit IL-10 expression by PBMCs. Conclusion: During SLIT, BAFF expression was decreased and related to low Th2 cytokine expression and enhanced IL-10 expression. Besides, BAFF may contribute to local production of IgA. Our results suggested that BAFF may be an important biomarker during SLIT. Authors’ summary. Sublingual immunotherapy (SLIT) is the only therapeutic option for allergic rhinitis (AR) that modifies the immunological process to an allergen, rather than simply treating symptoms. However, its regulatory mechanisms are largely unknown. B-cell-activating factor of the TNF family (BAFF) plays very important roles in the development, differentiation, and proliferation of B cells and T cells. Our results showed that during SLIT, BAFF expression was decreased and related to low Th2 cytokine expression and enhanced IL-10 expression. Besides, BAFF may contribute to local production of IgA. Our results suggested that BAFF may be an important biomarker during SLIT. 相似文献
52.
Hongli Wu Meng Zou Lisheng Guo Fengyun Ma Wenlong Mo Yuming Yu Inamullah Mian Jingmei Liu Shuangjie Yin Noritatsu Tsubaki 《RSC advances》2020,10(7):4166
A series of Ni–La/Al2O3 catalysts for the syngas methanation reaction were prepared by a mechanochemical method and characterized by thermogravimetric analysis (TG-DTA), X-ray fluorescence (XRF), X-ray diffraction (XRD), N2 adsorption–desorption, H2 temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The calcination temperatures (350–700 °C) had significant impacts on the crystallite sizes and interactions between NiO and Al2O3. The catalyst calcined at 400 °C (cat-400) showed a 12.1% Ni dispersion degree and the maximum bound state of NiO (54%) through the Gaussian fitting of H2-TPR. Cat-400 also achieved the highest CO conversion, CH4 selectivity and yield. Cat-400 exhibited good stability and catalytic activity in a lifetime testing of 200 h. The deactivation of cat-400 was mainly caused by carbon deposition according to the data from XRD, TG-DTG and XPS.Calcination temperature affects the existing types of NiO, and the influence of the three NiO types on the catalytic activity of samples is bound type ≫ free type > combined type. 相似文献
53.
Xianlong Gao Wenlong Mo Fengyun Ma Tsubaki Noritatsu Hongli Wu Xing Fan 《RSC advances》2020,10(10):5516
Three commercial Ni–Al alloys formed by a vacuum atomization method (NAV), atmospheric atomization method (NAA) and high-temperature melting method (NAH) were leached by 10 wt% NaOH solution to prepare three RANEY®-Ni catalysts (RNAV, RNAA and RNAH, correspondingly). The effects of a forming process on the structure of Ni–Al alloys and the corresponding RANEY®-Ni catalysts were investigated via XRD, XPS, SEM, TEM, NH3-TPD, N2 adsorption–desorption and EDX-mapping studies. Also, the as-prepared RANEY®-Ni catalysts were evaluated via the hydrogenation of 1,4-butenediol (BED) to produce 1,4-butanediol (BDO). The results showed that the specific surface areas and surface morphologies of the Ni–Al alloys present significant differences. Meanwhile, the RNAA sample presented a comparatively regular morphology, similar to a small piece of sugar cane. The weak and medium acid peak areas of the RNAA catalyst were lower than those of the other samples. RNAV showed higher weak and medium acid peak areas, demonstrating the higher number of acid centers on the surface of the catalyst. The surface of the RNAA catalyst obtained from NAA contained more active component-Ni, about 90 wt% on the surface, and the specific surface area of the sample was 75 times that of its precursor Ni–Al alloy powder (NAA). The evaluation results present that the RNAA catalyst shows better hydrogenation performance, with BED conversion of 100%, both BDO selectivity and yield of 46.11%.Xianlong Gao''s paper focuses on the effects of a forming process on the catalytic hydrogenation of 1,4-butenediol (BED) to produce 1,4-butanediol (BDO). The evaluation results showed that the RNAA catalyst showed excellent hydrogenation performance. 相似文献
54.
目的:构建pEGFP—X真核表达载体,观察其在肝癌细胞株中的表达。方法:从质粒pcDNA3.1(+)-X酶切获HBVX基因片段,克隆至pEGFP—N1;用酶切、PCR和测序鉴定pEGFP—X载体;用脂质体法,将重组载体(pEGFP—X)和空载体(pEGFP-N1)瞬时转染肝癌细胞细胞株BEL-7402;分别用RT—PCR、荧光显微镜鉴定HBVX和EGFP基因表达。结果:鉴定证实pEGFP-X载体构建成功;该质粒瞬时转染的BEL-7402有HBVX基因表达,并发绿色荧光。结论:构建的pEGFP—X真核载体能在BEL-7402中表达,绿色荧光蛋白示踪利于表达HBVX基因稳定细胞株的筛选,并为探讨HBVX基因在HCC中的致瘤机理提供实验模型奠定基础。 相似文献
55.
目的研究截断逆挽方含药血清通过调控E2F1介导的细胞增殖途径减轻D-氨基半乳糖(D-Galactosamine,D-GlaN)诱导的人正常肝细胞LO2的损伤。方法体外培养LO2细胞,以D-GlaN进行造模,将细胞分为正常组、模型组、2.5%截断逆挽方含药血清组(2.5%JDNWF)、5%截断逆挽方含药血清组(5%JDNWF)、10%截断逆挽方含药血清组(10%JDNWF)。采用Cell Counting Kit-8(CCK8)法检测细胞活力;Real-time PCR检测转录因子E2F1、细胞周期蛋白E(cyclin E)、细胞周期蛋白A(cyclin A)、细胞周期蛋白依赖性激酶2(cyclin-dependent kinase 2,CDK2)、细胞分裂周期因子25A(cell division cyclin 25A,CDC25A)mRNA的表达;流式细胞术检测细胞周期;Western Blot检测分化调控因子DP1蛋白表达。结果截断逆挽方含药血清能显著促进LO2细胞进入S期(P<0.01),上调E2F1、cyclin E、cyclin A、CDK2、CDC25A mRNA的表达(P<0.01),并且能增加DP1蛋白的表达(P<0.05,P<0.01)。结论截断逆挽方减轻肝细胞损伤的作用机制可能与其促进肝细胞增殖有关。 相似文献
56.
Lihua Huang Li Zhou Jianhe Gan Wenlong Yang Yaping Dai Tingting Su Yuanwang Qiu 《The Turkish journal of gastroenterology》2021,32(2):178
Background: To investigate the association between interleukin-21 (IL-21) expression level and virological relapse (VR) of HBeAg positive chronic hepatitis B (CHB) after discontinuance of entecavir (ETV).Methods: The serum IL-21 level of 112 CHB patients was measured at 0, 12, 24, 52, and 104 weeks after ETV discontinuance. ELISA was used for the measurement of serum IL-21 level. VR was defined as two continuous examinations with an interval of 1 month with both showing HBV DNA >10 000 copies/mL after drug discontinuance.Results: The serum IL-21 levels at 0, 12, 24, 52, and 104 weeks after discontinuance of ETV were significantly higher in the durable virological remission (DVR) group than in the VR group (all P < .01). The area under the ROC curve (AUC) was 0.728 (95% CI: 0.630-0.827, P < .001), while the best cut-off value was 49.8 pg/mL. Multivariate Cox model showed that the factors affecting the relapse included age, followed by HBsAg level at the serological conversion of HBeAg and serum IL-21 level (all P < .05).Conclusion: Serum IL-21 level at ETV discontinuance is an independent risk factor for CHB relapse. IL-21 acts as an immunomodulatory factor in maintaining DVR in HBeAg positive CHB patients after ETV discontinuance. 相似文献
57.
Changmin Hou Zhao Cui Sai Zhang Wenlong Yang Hongtao Gao Xiliang Luo 《RSC advances》2021,11(59):37624
Transition metal layered double hydroxides (LDHs) with ultrathin two-dimensional (2D) structures, especially NiFe-based LDH nanosheets, have been extensively developed as advanced oxygen evolution reaction (OER) electrocatalysts for water splitting. Nevertheless, traditional synthetic approaches for these promising catalysts usually involve tedious pretreatment procedures and a subsequent time-consuming exfoliation process, and the obtained products possess a wide dispersion of thickness and limited production yield. Here, a sequence of ultrathin NiFe-LDH nanosheets with tunable components were prepared on a large scale via a rapid room-temperature method under ambient conditions, and were further used as a desired material model for studying the influence of Ni/Fe ratio modulation on the OER performance. Due to the synergetic effect of more exposed active sites, efficient electron transport and optimized OER kinetics, the resulting LDH samples manifest outstanding electrocatalytic performance toward water oxidation.A sequence of ultrathin NiFe-LDH nanosheets with tunable components were prepared via a rapid room-temperature method, which were further used as efficient electrocatalysts for water oxidation. 相似文献
58.
Xiaoduo Gao Fengyu Shi Fei Peng Xuejuan Shi Caihong Cheng Wenlong Hou Haicui Xie Xiaohu Lin Xiuping Wang 《RSC advances》2021,11(57):36089
Nanopesticides with controlled release can achieve more effective utilization of pesticides. Here, to enhance the adsorption of pesticides onto the target organisms, the formulation of pesticides with temperature-responsive release was proposed by combing graphene oxide (GO) and existing pyrethroid pesticides (cyhalothrin, bifenthrin and fenpropathrin). Pesticides were loaded onto GO nanosheets as a carrier via a simple physisorption process, and the GO–pesticide nanocomposites exhibited temperature-responsive release and excellent storage stability, which are of vital importance to the practical application. Furthermore, we assessed the bioactivity of the GO–pesticide nanocomposites against spider mites (Tetranychus urticae Koch) indoors and in the field. As a result, GO–pesticide nanocomposites had many folds higher bioactivity than individual pesticides, and could be adsorbed on the cuticle of T. urticae and surface of bean leaves with highly uniform dispersibility. The easy preparation and higher bioactivity of GO–pesticide nanocomposites indicate their promising application potential in pest control and green agriculture.Nanopesticides with controlled release can achieve more effective utilization of pesticides. 相似文献
59.
目的探讨淫羊藿素联合达拉菲尼对人黑素瘤A375细胞增殖和转移的抑制作用及可能的机制。方法采用不同浓度淫羊藿素和达拉菲尼单独及联合作用于A375细胞;CCK-8法检测细胞生长抑制率,进行协同性分析;Transwell和划痕实验检测细胞迁移和侵袭能力;qPCR及Westernblot检测MMP-2、MMP-9、Vimentin和E-cadherin的表达情况。结果淫羊藿素和达拉菲尼均能下调A375细胞MMP-2、MMP-9和Vimentin的表达,上调E-cadherin的表达,抑制其增殖、迁移和侵袭,且两药低浓度联合具有协同效应。结论淫羊藿素能协同达拉菲尼抑制A375细胞MMP-2、MMP-9和Vimentin的表达,促进E-cadherin的表达,抑制黑素瘤细胞的增殖和转移。 相似文献
60.
目的探讨儿童左束支区域起搏(LBBAP)的安全性及有效性.方法回顾性分析2019年1月至6月于北京安贞医院小儿心脏科住院采用LBBAP方式行永久心脏起搏器植入术的6例患儿(男1例、女5例)的临床资料、起搏心电图及参数并进行随访.组间比较采用t检验.结果6例患儿年龄9~14岁,体重26~48 kg;三度房室传导阻滞5例,右室心尖起搏术后伴心功能下降1例;1例患儿心功能降低,余5例心功能均正常;QRS波时限(95±13)ms;左心室舒张末径(LVEDD)Z值为1.85±0.65.起搏心电图V1呈右束支传导阻滞样,QRS波时限(111±20)ms,与术前相比,差异无统计学意义(t=-1.610,P>0.05).起搏阈值为(0.85±0.26)V,感知(15.0±4.3)mV,阻抗(717±72)Ω.3例可记录到P电位.起搏钉至左心室激动时间为(56±5)ms,不同输出电压下数值恒定.术后超声提示电极均位于室间隔左心室心内膜下.随访无心肌穿孔、电极脱位等并发症发生,患儿术后3个月阈值、感知及阻抗分别为(0.60±0.09)V、(16.1±3.9)mV、(662±78)Ω.左心室射血分数(LVEF)降低者LBBAP术后3d恢复正常(45%比57%).术后3个月LVEDD Z值降至(1.1±0.3),较术前明显减小(t=2.383,P<0.05).结论LBBAP可实现窄QRS波起搏,接近生理性起搏,起搏参数稳定,可快速、有效地纠正长期心动过缓所致的左心扩大及长期右室心尖起搏所致的心功能低下及心脏扩大.较大年龄儿童行LBBAP近期安全性、有效性好,远期潜在风险有待进一步观察研究. 相似文献