全文获取类型
收费全文 | 1893篇 |
免费 | 153篇 |
国内免费 | 46篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 12篇 |
妇产科学 | 2篇 |
基础医学 | 321篇 |
口腔科学 | 40篇 |
临床医学 | 117篇 |
内科学 | 255篇 |
皮肤病学 | 175篇 |
神经病学 | 123篇 |
特种医学 | 75篇 |
外科学 | 54篇 |
综合类 | 202篇 |
预防医学 | 107篇 |
眼科学 | 38篇 |
药学 | 421篇 |
中国医学 | 107篇 |
肿瘤学 | 31篇 |
出版年
2023年 | 27篇 |
2022年 | 14篇 |
2021年 | 68篇 |
2020年 | 51篇 |
2019年 | 49篇 |
2018年 | 62篇 |
2017年 | 57篇 |
2016年 | 50篇 |
2015年 | 78篇 |
2014年 | 91篇 |
2013年 | 121篇 |
2012年 | 96篇 |
2011年 | 130篇 |
2010年 | 94篇 |
2009年 | 59篇 |
2008年 | 84篇 |
2007年 | 86篇 |
2006年 | 59篇 |
2005年 | 69篇 |
2004年 | 47篇 |
2003年 | 65篇 |
2002年 | 49篇 |
2001年 | 37篇 |
2000年 | 33篇 |
1999年 | 35篇 |
1998年 | 28篇 |
1997年 | 26篇 |
1996年 | 32篇 |
1995年 | 35篇 |
1994年 | 23篇 |
1993年 | 28篇 |
1992年 | 23篇 |
1991年 | 28篇 |
1990年 | 20篇 |
1989年 | 23篇 |
1988年 | 31篇 |
1987年 | 15篇 |
1986年 | 15篇 |
1985年 | 25篇 |
1984年 | 23篇 |
1983年 | 17篇 |
1982年 | 29篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1970年 | 2篇 |
排序方式: 共有2092条查询结果,搜索用时 15 毫秒
1.
目的探讨钆塞酸二钠(Gadolinium ethoxybenzyl diethylene-triamine-pentaacetic-acid,Gd-EOB-DTPA)动态对比增强MRI(dynamic contrast-enhanced magnetic resonance imaging,DCE-MRI)定量评估大鼠中度肝纤维化(hepatic fibrosis,HF)的价值。材料与方法40只雄性Wistar大鼠(对照组10只,实验组30只),腹腔注射CCl4构建不同分期HF模型,并行肝脏轴位T1WI及DCE-MRI扫描,获取以下参数:容量转运常数(Ktrans)、速率常数(Kep)、血管外细胞外间隙体积百分数(Ve)以及初始曲线下面积(iAUC)。所有大鼠扫描前行尾静脉采血,测定血清中透明质酸(hyaluronic acid,HA)、层粘连蛋白(laminin,LN)含量。扫描结束后取大鼠肝脏组织进行HF病理学分期。采用独立样本t检验比较正常组与实验组、正常组及轻度HF组与中度HF组DCE-MRI参数和血清学指标的差异;采用单因素方差分析比较DCE-MRI参数和血清学指标在不同HF分期之间的差异;采用Spearman相关检验分析DCE-MRI参数和血清学指标与HF分期的相关性;利用ROC曲线比较各参数诊断中度HF的价值。结果26只大鼠纳入本次研究,其中病理学分期为正常组6只、轻度HF(F1期)7只、中度HF(F2~F3期)13只,随着HF加重,Ktrans、Kep、Ve及iAUC均降低(r=-0.665,P<0.001;r=-0.395、P=0.046;r=-0.565、P=0.003;r=-0.538、P=0.005),血清LN及HA含量均升高(r=0.606,P=0.001;r=0.601,P=0.001);Ktrans、Ve及iAUC在实验组与正常组、正常组及轻度HF组与中度HF组、正常组与中度HF组、轻度HF与中度HF组间差异均有统计学意义(P<0.05);血清LN及HA含量在对照组与中度HF组之间差异具有统计学意义(P<0.05);ROC曲线显示Ktrans及LN诊断中度HF效能最高。结论Gd-EOB-DTPA DCE-MRI定量评估对中度HF分期具有较好的诊断价值,其中DCE-MRI参数中Ktrans具有最佳的诊断效能。 相似文献
2.
《Nutrition, metabolism, and cardiovascular diseases : NMCD》2022,32(5):1227-1235
Background and aimsAlthough antithrombotic treatments are established for coronary artery disease (CAD), they increase the bleeding risk, especially in malnourished patients. The total thrombus-formation analysis system (T-TAS) is useful for the assessment of thrombogenicity in CAD patients. Here, we examined the relationships among malnutrition, thrombogenicity and 1-year bleeding events in patients undergoing percutaneous coronary intervention (PCI).Methods and resultsThis was a retrospective analysis of 300 consecutive CAD patients undergoing PCI. Blood samples obtained on the day of PCI were used in the T-TAS to compute the thrombus formation area under the curve. We assigned patients to two groups based on the geriatric nutritional risk index (GNRI): 102 patients to the lower GNRI group (≤98), 198 patients to the higher GNRI group (98<). The primary endpoint was the incidence of 1-year bleeding events defined by Bleeding Academic Research Consortium criteria types 2, 3, or 5. The T-TAS levels were lower in the lower GNRI group than in the higher GNRI group. Kaplan-Meier analysis showed worse 1-year bleeding event-free survival in the lower GNRI group compared with the higher GNRI group. The combined model of the GNRI and the Academic Research Consortium for High Bleeding Risk (ARC-HBR) had good calibration and discrimination for bleeding risk prediction. In addition, having a lower GNRI and ARC-HBR positivity was associated with 1-year bleeding events.ConclusionA lower GNRI could reflect low thrombogenicity evaluated by the T-TAS and determine bleeding risk in combination with ARC-HBR positivity. 相似文献
3.
目的 将质量常数中药饮片等级划分方法应用于麸炒苍术饮片的等级评价中,以期建立合理的麸炒苍术饮片等级标准。方法 收集来自主要中药材交易市场及其道地产区、主产区的不同厂家、不同规格、不同批号、不同产地的22批麸炒苍术饮片样品,对其外观形态参数、指标成分含量进行测定,通过计算其质量常数(A)及百分质量常数(A%)对22批麸炒苍术饮片样品进行等级划分。结果 所收集的22批麸炒苍术饮片样品的A为0.92~3.37;若将麸炒苍术样品分为3个等级,一等品为A%≥80%(A≥2.70)的麸炒苍术饮片,共有1批;二等品为50%≤A%<80%的麸炒苍术饮片(1.69≤A<2.70),共有11批;其余10批为三等品,即A%<50 %(A<1.69)的饮片。结论 质量常数方法用于划分麸炒苍术饮片等级是可行的,能更为全面、客观地反映不同等级麸炒苍术饮片的质量。 相似文献
4.
Efficient Polymer Solar Cells Based on New Random Copolymers with Porphyrin‐Incorporated Side Chains
Zhixin Liu Zhuohao Huang Yuzhuo Chen Tao Xu Hao Yu Xia Guo Lei Yan Maojie Zhang Wai‐Yeung Wong Xingzhu Wang 《Macromolecular chemistry and physics.》2020,221(1)
Two new wide bandgap block copolymers (PL1 and PL2) with porphyrin‐incorporated side chains are designed and used as electron donors for solution‐processed bulk heterojunction polymer solar cells. The photophysical, electrochemical, and photovoltaic properties, charge transport mobility and film morphology of these two block copolymers are investigated. Detailed investigations reveal that the different alkyl groups and electron‐withdrawing substituents on the porphyrin pendant units have significant influence on the polymer solubility, absorption energy level, band gap, and charge separation in the bulk‐heterojunction thin films, and thus the overall photovoltaic performances. Organic photovoltaic devices derived from these copolymers and ([6,6]‐phenyl‐C71‐butyric acid methyl ester) (PC71BM) acceptor show the best power conversion efficiencies of 5.83% and 7.14%, respectively. These results show that the inclusion of a certain proportion of side chain porphyrin group as a pendant in the traditional donor‐acceptor (D‐A) type polymer can broaden the molecular absorption range and become a full‐color absorbing molecule. The size of the porphyrin pendant also has an obvious effect on the properties of the molecule. 相似文献
5.
6.
钱雪飞 《南通大学学报(哲学社会科学版)》2015,(4)
本文基于南通市“巾帼挽霞行动”社工服务项目的实践探索,通过对社区志愿者、社团志愿者及高校学生志愿者持续参与志愿服务状况的比较分析,认为志愿服务由社团来承担具有诸多的优越性。社团应逐步成为持续志愿服务的承担主体。社团的志愿服务化以及志愿者的社团化应该成为持续志愿服务管理的努力方向。 相似文献
7.
Evidence‐ and consensus‐based (S3) Guidelines for the Treatment of Actinic Keratosis – International League of Dermatological Societies in cooperation with the European Dermatology Forum – Short version 下载免费PDF全文
R.N. Werner E. Stockfleth S.M. Connolly O. Correia R. Erdmann P. Foley A.K. Gupta A. Jacobs H. Kerl H.W. Lim G. Martin M. Paquet D.M. Pariser S. Rosumeck H.‐J. Röwert‐Huber A. Sahota O.P. Sangueza S. Shumack B. Sporbeck N.A. Swanson L. Torezan A. Nast 《Journal of the European Academy of Dermatology and Venereology》2015,29(11):2069-2079
8.
目的探讨直肠癌动态对比增强磁共振成像(DCE-MRI)参数的特点及其与病理分化程度、Dukes分期的关系。材料与方法对56例经病理证实为直肠癌患者的DCE-MRI图像进行回顾性分析,绘制时间-信号强度曲线(TIC)、构建Ktrans、Ve、Kep参数图,并分析TIC、Ktrans、Ve、Kep值的特点及其与肿瘤分化程度、Dukes分期的相关性。结果将直肠癌及肿瘤周围正常直肠壁的TIC分为3种类型,其中Ⅱ型8例,Ⅲ型48例,肿瘤周围正常直肠壁Ⅰ型为41例、Ⅱ型15例。直肠癌的Ktrans值随肿瘤分化程度减低,Dukes分期增加而升高(P值均0.01);Ve、Kep值差异无统计学意义。结论 DCE-MRI能反映肿瘤内部的血流动力学情况,TIC及Ktrans值与直肠癌的病理分化程度、Dukes分期具有一定相关性,TIC及Ktrans值可能用于评价直肠癌的恶性程度。 相似文献
9.
10.
Mohammad Raish Ajaz Ahmad Mushtaq Ahmad Ansari Khalid M. Alkharfy Abdul Ahad Altaf Khan Fahad I. Aljenobi Naushad Ali Abdullah M. Al-Mohizea 《Yao wu shi pin fen xi = Journal of food and drug analysis.》2019,27(1)
Dietary supplements and foods can interact with various drugs, leading to possible clinical concerns. This study aimed to investigate the effect of orally administered sinapic acid (SA) on the pharmacokinetics of aripiprazole (APZ) in rats and its possible modulatory effects on hepatic cytochrome P450 (CYP3A2 and CYP2D6) expression in the liver tissues. Single dose and multiple dose parallel groups of wistar rats were categorized into six groups (n = 6 each) which abstained from food for 12 h prior to the experiment, while water was allowed ad libitum. The investigation was carried out for single dose: Group I was treated with normal saline orally for 15 days (normal control). Group II was administered normal saline orally for 15 days and received APZ (3 mg/kg p.o.) on day 15. Group III received SA (20 mg/kg p.o.) for 15 days and received APZ (3 mg/kg p.o.) on day 15. Group IV was treated with SA (20 mg/kg p.o.) for 15 days. For the multiple dose study, Group I was treated with normal saline orally for 15 days (normal control); Group II received APZ (3 mg/kg p.o.) daily for 15 days; Group III was administered with SA (20 mg/kg p.o.) and APZ (3 mg/kg p.o.) for 15 days and Group IV received SA (20 mg/kg p.o.) for 15 days. The group I and IV were kept common in single and multiple dose groups. After last APZ dose, plasma samples were collected and APZ concentrations were determined using an UPLC-MS/MS technique. The pharmacokinetic parameters were calculated using a non-compartmental analysis. The concomitant administration of APZ with SA (as single or multiple dose) resulted in an increase in APZ absorption and a decrease on its systemic clearance. This was associated with a reduction in CYP3A2 and CYP2D6 protein expressions by 33–43% and -71–68% after the single and multiple co-administration, which are two enzymes responsible of the metabolism of APZ. Therefore, a reduction in the metabolic clearance appears to be the mechanism underlying the drug interaction of dietary supplement containing SA with APZ. Therefore, the concomitant administration of SA and APZ should be carefully viewed. Further investigations are required to assess the clinical significance of such observations in humans. 相似文献