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   8045篇
  免费   807篇
  国内免费   443篇
耳鼻咽喉   23篇
儿科学   95篇
妇产科学   116篇
基础医学   662篇
口腔科学   335篇
临床医学   912篇
内科学   896篇
皮肤病学   102篇
神经病学   377篇
特种医学   284篇
外国民族医学   1篇
外科学   570篇
综合类   1268篇
一般理论   1篇
预防医学   1139篇
眼科学   128篇
药学   1218篇
  19篇
中国医学   523篇
肿瘤学   626篇
  2024年   24篇
  2023年   153篇
  2022年   222篇
  2021年   357篇
  2020年   395篇
  2019年   312篇
  2018年   293篇
  2017年   327篇
  2016年   339篇
  2015年   335篇
  2014年   508篇
  2013年   801篇
  2012年   498篇
  2011年   520篇
  2010年   428篇
  2009年   414篇
  2008年   350篇
  2007年   380篇
  2006年   333篇
  2005年   307篇
  2004年   258篇
  2003年   220篇
  2002年   198篇
  2001年   176篇
  2000年   120篇
  1999年   110篇
  1998年   82篇
  1997年   75篇
  1996年   65篇
  1995年   146篇
  1994年   72篇
  1993年   56篇
  1992年   47篇
  1991年   42篇
  1990年   46篇
  1989年   37篇
  1988年   28篇
  1987年   33篇
  1986年   18篇
  1985年   23篇
  1984年   24篇
  1983年   13篇
  1982年   28篇
  1981年   14篇
  1980年   16篇
  1979年   10篇
  1978年   6篇
  1977年   12篇
  1976年   6篇
  1975年   7篇
排序方式: 共有9295条查询结果,搜索用时 15 毫秒
1.
目的:运用新型光学生物测量仪IOL Master 700测量白内障超声乳化手术前后眼部生物学参数的变化,并探讨人工晶状体(IOL)屈光度数计算公式的选择。

方法:前瞻性研究。收集2021-01/06在苏州大学附属第一医院就诊的白内障患者52例57眼。术前和术后3mo使用IOL Master 700完成眼轴长度(AL)、前房深度(ACD)、角膜曲率(Km)的测量并分析。对不同IOL公式计算时预留的目标屈光值与术后3mo全自动验光仪实际屈光值结果进行比较并分析。

结果:手术前后测量的AL平均值分别为24.20±1.86、24.09±1.86mm,术后AL缩短了0.11mm; ACD值分别为3.08±0.44、4.55±0.36mm(P<0.001),术后ACD加深1.49mm; Km值分别为44.14±1.86、44.14±1.82D(P>0.05)。术前选用Barrett Universal Ⅱ公式所测结果的屈光误差最小,其次是Holladay Ⅱ及SRK/T公式,Holladay Ⅰ公式所测结果的误差最大(P<0.05)。

结论:白内障术后AL缩短以及ACD加深,度数测算时可考虑增加0.1mm的校正因子。IOL屈光度数计算公式中Barrett Universal Ⅱ公式预测性最佳,其次是Holladay Ⅱ及SRK/T公式。  相似文献   

2.
We carried out a longitudinal study on the associations between residential greenness and depression risk in urban areas in Finland. Residential greenness indicators were estimated within various buffer sizes around individuals' home locations (selected n = 14424) using time-series of normalized differential vegetation index (NDVI) and CORINE land cover data (CLC). We estimated individuals’ cumulative exposure to residential greenness over a 5-years and 14-years follow-up. We used doctor-diagnosed depression and Beck Depression Inventory for depression assessment. Our multi-logistic model showed an inverse association between residential greenness and depression, implying lowered depression risk for individuals with higher residential greenness. The association was particularly evident when using NDVI-based residential greenness (within a buffer of 100 m radius) and doctor-diagnosis depression data, adjusted with individual-level covariates. The odds ratio was 0.56 (95% CI 0.33 to 0.96) for the 5-years follow-up, and 0.54 (95% CI 0.30 to 0.98) for the 14-years follow-up. The associations between CLC-based total residential green space and depression varied across the different buffer sizes. In general, all the associations depended on the type of depression assessment, quality of greenness indicators, and the spatial scale of analysis. The associations also varied across the socio-demographic groups and neighborhood socioeconomic disadvantage level.  相似文献   
3.
目的 观察结肠癌HCT116细胞健脾消癌方的条件培养液对HUVEC细胞管腔形成的影响,从PI3K/Akt生物轴调控角度探讨其作用机制。方法 培养HCT116细胞,细胞设3组:对照组,健脾消癌方组(加入15%健脾消癌方含药血清)及人参皂苷Rg3组;制备HCT116细胞健脾消癌方条件培养液(分组及制备方法见实验方法),用条件培养液干预HUVEC(脐静脉内皮细胞,Human Umbilical Vein Endothelial Cells),Matrigel基质胶法检测HCT116细胞健脾消癌方条件培养液对HUVEC小管形成的影响。随后采用蛋白免疫印迹法(Western blot)检测各组HCT116细胞磷脂酰肌醇3-激酶(PI3K)、蛋白激酶B(Akt)、p-Akt、VEGF(血管内皮生长因子,Vascular endothelial growth factor)蛋白表达。最后在结肠癌HCT116荷瘤小鼠中验证健脾消癌方对肿瘤生长速度的影响,并经瘤组织VEGF蛋白表达、CD31免疫组化染色检测肿瘤内血管生成情况。结果 模型组HUVEC细胞管腔形成较空白血清组显著增加(P<0.05);健脾消癌方组及人参皂苷Rg3组较模型组HUVEC细胞管腔形成显著减少(P<0.01)。p-Akt和VEGF蛋白表达水平模型组高于空白血清组(P<0.05),健脾消癌方组及人参皂苷Rg3组显著低于模型组(P<0.01);PI3K、Akt蛋白表达量组间差异无统计学意义。与对照组比较,模型组荷瘤小鼠肿瘤体积显著性增大,瘤组织内VEGF表达、CD31阳性面积显著性增加,差异有统计学意义(P<0.05);与模型组比较,健脾消癌方组及人参皂苷Rg3组荷瘤小鼠肿瘤体积显著减小,瘤组织内VEGF表达、CD31阳性面积降低,差异有统计学意义(P<0.05)。结论 健脾消癌方可抑制肿瘤的血管生成和生长,其作用机制可能与PI3K/Akt生物轴调控VEGF表达有关。  相似文献   
4.
ObjectivesWe evaluated breast cancer (BC) care quality indicators (QIs) in clinical pathways and integrated health care processes.MethodsFollowing protocol registration (Prospero no: CRD42021228867), relevant documents were identified, without language restrictions, through a systematic search of bibliographic databases (EMBASE, Scopus, Web of Science, MEDLINE), health care valuable representatives and the World Wide Web in April 2021. Data concerning QIs, measurement tools and compliance standards were extracted from European and North American sources in duplicate with 98% reviewer agreement.ResultsThere were 89 QIs found from 22 selected documents (QI per document mean 13.5 with standard deviation 11.9). The Belgian (38 QIs) and the EUSOMA (European Society of Breast Cancer Specialists) (34 QIs) documents were the ones that best reported the QIs. No identical QI was identified in all the documents analysed. There were 67/89 QIs covering processes (75.3%) and 11/89 (12.4%) for each structure and outcomes QIs. There were 21/89 QIs for diagnosis (30.3%), 43/89 for treatment (48.3%), and 19/89 for staging, counselling, follow-up and rehabilitation (21.4%). Of 67 process QIs and 11 outcome QIs, 20/78 (26%) did not report a minimum standard of care. Shared decision making was only included as a QI in the Italian document.ConclusionMore than half of countries have not established a national clinical pathway or integrated breast cancer care process to achieve the excellence of BC care. There was heterogeneity in QIs for the evaluation of BC care quality. Over two-thirds of the clinical pathways and integrated health care processes did not provide a minimum auditable standard of care for compliance, leaving open the definition of best practice. There is a need for harmonisation of BC care QIs.  相似文献   
5.
6.
蛋白质精氨酸甲基转移酶1(protein arginine methyltransferase 1,PRMT1)是主要的Ⅰ型精氨酸甲基转移酶,催化一甲基化和不对称二甲基化,其底物被甲基化后参与细胞生物学过程。研究表明,PRMT1在多种恶性肿瘤中异常表达,促进肿瘤细胞的增殖、侵袭和迁移,调控人类多种肿瘤发生发展过程,揭示PRMT1可能成为肿瘤治疗中潜在的生物标志物或靶点。本文对PRMT1的结构、底物、生物学功能、及其在肿瘤发生发展中的作用进行总结,旨在为今后研究PRMT1相关肿瘤提供参考。  相似文献   
7.
目的:探究三结构域蛋白59(TRIM59)调控人皮肤黑色素瘤细胞SK-MEL-2增殖、细胞周期、凋亡及迁移侵袭的作用机制,及其与Bcl2相关转录因子1(BCLAF1)之间的关系。方法:qPCR和WB法检测人表皮黑色素细胞HEMn-LP、人皮肤黑色素瘤细胞SK-MEL-2、UACC903、A375及36例邢台市人民医院2019年2月至2021年7月收集的皮肤黑色素瘤组织中TRIM59的mRNA和蛋白表达,使用脂质体将si-con、si-TRIM59转染至SK-MEL-2细胞中,WB法检测干扰TRIM59表达对细胞中周期蛋白D1(CCND1)、细胞周期素依赖性激酶2(CDK2)、肿瘤抑制蛋白基因(TP53)和 BCLAF1 蛋白表达的影响,CCK-8法、流式细胞术、划痕愈合实验、Transwell实验检测对细胞的活性、凋亡、迁移和侵袭的影响,免疫共沉淀(Co-IP)实验检测对细胞中TRIM59蛋白与BCLAF1结合能力的影响。结果:与HEMn-LP细胞相比,SK-MEL-2、UACC903、A375细胞中TRIM59 mRNA和TRIM59、BCLAF1蛋白均呈高表达(均P<0.05),SK-MEL-2细胞中TRIM59表达水平最高。相较于si-con组和Normal组,沉默TRIM59后,SK-MEL-2细胞的活性显著降低,细胞周期阻滞于G2期,CCND1、CDK2的蛋白表达显著降低,TP53蛋白和细胞凋亡率均显著升高,划痕抑制率明显升高,迁移侵袭细胞数明显降低(均P<0.05)。免疫共沉淀实验结果显示,TRIM59与BCLAF1之间存在蛋白结合关系。TRIM59与 BCLAF1 在肿瘤组织中的表达呈显著的正相关(r=0.878,P<0.001)。结论:干扰TRIM59表达能够抑制人皮肤黑色素瘤SK-MEL-2细胞的增殖、迁移和侵袭而促进凋亡,抑制SK-MEL-2细胞的恶性生物学行为,其机制可能与TRIM59结合BCLAF1有关。  相似文献   
8.
《L'Encéphale》2019,45(6):482-487
ObjectiveAntipsychotics are the standard treatment for psychosis. However, when combined with other lifestyle factors they are partially responsible for an excessive mortality rate. A clinical and paraclinical monitoring of patients is therefore necessary. In 2011, this element led doctors and pharmacists to improve monitoring and formalize a follow-up adapted to inmate patients. The aim of this study was to assess the impact of medical-pharmaceutical collaboration on monitoring quality of patients treated by antipsychotics.MethodsThis is a retrospective study including all patients treated by antipsychotics for at least 6 months in 2011 and again in 2015. Data were collected from medical files. The indicator assessing the monitoring quality was the compliance percentage, of registred parameters for each patient on the basis of specific guidelines.ResultsIn 2015 compared to 2011, the monitoring quality increased for 9 out of 10 parameters. This improvement was statisticaly significant for 7 of them : Body Mass Index, lipid test, complete blood count, transaminase, ionogram, glycemia, glomerular filtration rate.ConclusionThe actions of improvement collectivelly implemented in 2011 had a concrete impact on patients in the follow-up in 2015.  相似文献   
9.
10.
Steady-state axisymmetric simulations using the Reynolds-Averaged Navier-Stokes equations have been carried out in order to optimize the performance of a Chemical, Biological, Radiological, and Nuclear (CBRN) canister filter for its use in a powered air-purifying respirator (PAPR). Alterations have been made to the shape of the canister, the spacing of the rear wall of the canister with regard to the carbon filter, and the bracketing between (i) the particulate filter and the carbon bed and (ii) the carbon bed and the canister wall. The pressure drops across the canister and the residence time distribution at the rear of the carbon bed have been analyzed in detail based on an extensive parametric analysis involving the aforementioned variations. It has been demonstrated that the non-uniform porosity profile of the carbon bed resulted in alternating regions of high and low velocity close to the canister wall, providing a possible route for breakthrough. Designs, which included a bracket at the rear of the carbon bed, blocked this route and consequently had a longer minimum mean residence time than those, which did not. It has also been shown that the spacing between the carbon bed and the canister rear wall had a large impact on both residence time and pressure drop. In cases where the carbon backed directly onto the canister rear wall flow in the axial direction from the outside wall toward the canister axis resulted in far greater pressure drop and a reduction in minimum mean residence time within the carbon bed.  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