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   41080篇
  免费   4337篇
  国内免费   1120篇
耳鼻咽喉   195篇
儿科学   1667篇
妇产科学   339篇
基础医学   5200篇
口腔科学   618篇
临床医学   4496篇
内科学   9554篇
皮肤病学   934篇
神经病学   2283篇
特种医学   661篇
外国民族医学   4篇
外科学   2748篇
综合类   6525篇
现状与发展   4篇
一般理论   1篇
预防医学   2846篇
眼科学   507篇
药学   3875篇
  27篇
中国医学   2900篇
肿瘤学   1153篇
  2024年   165篇
  2023年   941篇
  2022年   1052篇
  2021年   2151篇
  2020年   2003篇
  2019年   1744篇
  2018年   1665篇
  2017年   1774篇
  2016年   1874篇
  2015年   1682篇
  2014年   3065篇
  2013年   3222篇
  2012年   2906篇
  2011年   3033篇
  2010年   2256篇
  2009年   2172篇
  2008年   2079篇
  2007年   1888篇
  2006年   1630篇
  2005年   1440篇
  2004年   1118篇
  2003年   895篇
  2002年   770篇
  2001年   686篇
  2000年   540篇
  1999年   464篇
  1998年   425篇
  1997年   347篇
  1996年   335篇
  1995年   255篇
  1994年   235篇
  1993年   217篇
  1992年   216篇
  1991年   164篇
  1990年   144篇
  1989年   125篇
  1988年   108篇
  1987年   109篇
  1986年   94篇
  1985年   110篇
  1984年   80篇
  1983年   56篇
  1982年   62篇
  1981年   50篇
  1980年   41篇
  1979年   32篇
  1978年   27篇
  1977年   25篇
  1976年   24篇
  1974年   12篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
The porcine circovirus type 2 (PCV2) is a swine infectious viral pathogen of great significance in global swine herds. It was recently detected at another Province of South Africa sequel to the first detection of North American‐like strain (PCV2a) at Gauteng about two decades ago, but there is a dearth of information about the genomic features and diversity of the viral strains in circulation within the country and the entire sub‐Saharan Africa region. To date, only one complete genome of the virus from South Africa is available on global data base. This current effort is therefore geared towards the full‐genome characterization of the circulating PCV2 strains in the pigs of Eastern Cape Province. With the use of conventional polymerase chain reaction method, fifteen complete PCV2 genomes were successfully amplified, sequenced and assembled from field samples obtained from non‐vaccinated pigs in the region. Neighbor Joining and Maximum Likelihood phylogenetic analyses of the ORF2 gene and full genomes unanimously showed that most of the assembled genomes (11) belong to genotype PCV2b. Furthermore, three of the characterized sequences formed clade with other reference mutant PCV2b and PCV2b subtype 1C (i.e. PCV2d) strains from the USA, China and South Korea. The last sequence, however, clustered with other reference strains belonging to PCV2 intermediate clade 2 (PCV2‐IM2), recently identified in a global PCV2 strains phylogenetic analysis. This study reports the first complete genome sequences of PCV2b, PCV2d and PCV2‐IM2 in pigs from South Africa, and it gives a possible insight into the genetic characteristics and variability of the viral strains presently in circulation within the country. It further emphasizes the need for more stringent measures in curtailing the introduction and spread of transboundary swine pathogens in the country and entire Southern African region.  相似文献   
42.

Background

Acute myocardial infarction (AMI) causes irreversible myocardial damage and release of inflammatory mediators, including cytokines, chemokines and miRNAs. We aimed to investigate changes in the levels of cytokines (IL-6, TNF-α and IL-10), miRNAs profiles (miR-146 and miR-155) and distribution of different monocyte subsets (CD14++CD16-, CD14++CD16+, CD14+CD16++) in the acute and post-healing phases of AMI.

Methods

In eighteen consecutive AMI patients (mean age 56.78?±?12.4 years, mean left ventricle ejection fraction – LVEF: 41.9?±?9.8%), treated invasively, monocyte subsets frequencies were evaluated (flow cytometry), cytokine concentrations were analyzed (ELISA) as well as plasma miRNAs were isolated twice – on admission and after 19.2?±?5.9 weeks of follow-up. Measurements were also performed among healthy volunteers.

Results

AMI patients presented significantly decreased frequencies of classical cells in comparison to healthy controls (median 71.22% [IQR: 64.4–79.04] vs. 84.35% [IQR: 81.2–86.7], p?=?0.001) and higher percent of both intermediate and non-classical cells, yet without statistical significance (median 6.54% [IQR: 5.14–16.64] vs. 5.87% [IQR: 4.48–8.6], p?=?0.37 and median 5.99% [IQR: 3.39–11.5] vs. 5.26% [IQR: 3.62–6.2], p?=?0.42, respectively). In AMI patients both, analyzed plasma miRNA concentrations were higher than in healthy subjects (miR-146: median 5.48 [IQR: 2.4–11.27] vs. 1.84 [IQR: 0.87–2.53], p?=?0.003; miR-155: median 25.35 [IQR: 8.17–43.15] vs. 8.4 [IQR: 0.08–16.9], p?=?0.027, respectively), and returned back to the values found in the control group in follow-up. miR-155/miR-146 ratio correlated with the frequencies of classical monocytes (r=0.6, p?=?0.01) and miR-155 correlated positively with the concentration of inflammatory cytokines ? IL-6 and TNF-α.

Conclusions

These results may suggest cooperation of both pro-inflammatory and anti-inflammatory signals in AMI in order to promote appropriate healing of the infarcted myocardium.  相似文献   
43.
44.
45.
梁金  陈茜  张璇 《世界中医药》2020,15(1):71-75,80
目的:探究痛泻四神汤对腹泻型肠易激综合征胃肠激素水平的影响。方法:选取2017年2月至2018年6月西安市中医医院收治的腹泻型肠易激综合征患者124例作为研究对象,按照就诊顺序编号随机分为对照组和观察组,每组62例。对照组给予西医常规治疗,观察组在对照组基础上加用痛泻四神汤加减治疗,均治疗2周。观察和比较2组治疗前后淋巴细胞指标CD3^+、CD4^+、CD8^+、CD4^+/CD8^+变化,观察并比较2组治疗前后胃肠激素指标血浆胃动素(MOT)、降钙素相关基因肽(CGRP)、血管活性肠肽(VIP)、生长抑素(SS)、一氧化氮(NO)变化;观察并比较2组治疗前后在γ-干扰素(IFN-γ)、5-羟色胺(5-HT)、神经肽Y(NPY)含量变化;观察并比较2组治疗前后临床症状腹痛、腹胀、肠鸣失气、急躁易怒、神疲乏力、纳呆食少症状评分变化;治疗过程中进行不良反应记录,治疗结束后进行统计。结果:1)2组患者治疗前CD3^+、CD4^+、CD8^+、CD4^+/CD8^+比较,差异无统计学意义(P>0.05),治疗后2组CD3^+、CD4^+、CD4^+/CD8^+较治疗前均显著上升,CD8^+显著下降(均P<0.05);治疗后观察组患者CD3^+、CD4^+、CD4^+/CD8^+显著高于对照组,CD8^+显著低于对照组(P<0.05)。2)2组治疗前MOT、CGRP、VIP、SS、NO比较,差异无统计学意义(P>0.05),治疗后2组MOT、NO较治疗前显著升高,CGRP、VIP、SS显著下降(P<0.05);治疗后观察组CGRP、VIP、SS显著低于对照组,MOT、NO显著高于对照组(P<0.05)。3)2组治疗前IFN-γ、5-HT、NPY比较,差异无统计学意义(P>0.05),治疗后2组IFN-γ、5-HT、NPY较治疗前均显著下降(P<0.05);治疗后观察组IFN-γ、5-HT、NPY显著低于对照组(P<0.05)。4)2组治疗前腹痛、腹胀、肠鸣失气、急躁易怒、神疲乏力、纳呆食少积分比较,差异无统计学意义(P>0.05),治疗后2组以上各症状评分较治疗前显著下降(P<0.05);治疗后观察组以上各积分显著低于对照组(P<0.05)。5)2组口干、头痛、皮疹、胃肠道反应发生率比较,差异无统计学意义(P>0.05)。结论:痛泻四神汤能改善腹泻型肠易激综合征胃肠激素水平,改善临床症状,提高机体免疫力,提高疗效。  相似文献   
46.
47.
Introduction: The sodium-glucose co-transporter 2 (SGLT2) is ascribed to target renal tubular glucose re-absorption, and its inhibition has been proved to induce glucosuria which improves the glycemic index. Accordingly, SGLT2 inhibitors have found to be the promising class of antidiabetic agents for the management of type 2 diabetes mellitus. A large number of SGLT2 inhibitors have developed through structural modification and investigated for their ability to selectivity inhibit SGLT2 transporters with better bioavailability.

Areas covered: This review comprises a summary of patent applications (2013–2018) of SGLT2 inhibitors with focus on chemical structural advancement and therapeutic potentials in the management of diabetes and related disorders.

Expert opinion: SGLT2 inhibitors exert multiple metabolic benefits, including reduced glycated hemoglobin (HbA1c), improved glycemic control (fasting and postprandial), reduced body weight, reduced systolic and diastolic blood pressure and improved HDL cholesterol. Due to the virtue of no interference with insulin action and secretion, their efficacy remains the same even in presence of progressive β cell failure in type 2 diabetes. Additionally, few members of this class have been reported to exhibit cardioprotective, renoprotective, and anticancer activity. However, more study on the long-term outcomes in patients taking SGLT2 inhibitors is warranted.  相似文献   

48.
49.
50.
目的:探究风池穴不同刺法对椎动脉型颈椎病的临床疗效。方法:选择2018年4月—2019年1月北京中医药大学东直门医院针灸科门诊就诊的84例椎动脉型颈椎病患者作为研究对象,分为观察组43例、对照组41例。观察组采用短刺法针刺风池穴治疗,对照组采用平补平泻法针刺风池穴治疗,1个疗程后比较两组患者的ESCV、颈椎病症状分级量化表评分以及TCD相关指标,TCD指标观察基底动脉和双侧椎动脉的平均血流速度(Vm)、收缩期血流速度峰值(Vs)、血管搏动指数(PI)和血管阻力指数(RI)的变化。结果:治疗前后两组ESCV、颈椎病症状分级量化表评分比较,差异有统计学意义(P<0.05),且椎动脉、基底动脉的Vs、Vm较治疗前明显减慢,且观察组治疗效果优于对照组(P<0.05)。结论:针刺风池穴治疗椎动脉型颈椎病临床效果显著,且短刺法优于平补平泻法。  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