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   40187篇
  免费   3804篇
  国内免费   2609篇
耳鼻咽喉   445篇
儿科学   549篇
妇产科学   526篇
基础医学   5078篇
口腔科学   674篇
临床医学   5203篇
内科学   6017篇
皮肤病学   808篇
神经病学   2103篇
特种医学   1594篇
外国民族医学   23篇
外科学   3638篇
综合类   5857篇
现状与发展   8篇
一般理论   10篇
预防医学   2843篇
眼科学   1153篇
药学   4596篇
  24篇
中国医学   2250篇
肿瘤学   3201篇
  2024年   115篇
  2023年   602篇
  2022年   1568篇
  2021年   1998篇
  2020年   1516篇
  2019年   1422篇
  2018年   1471篇
  2017年   1420篇
  2016年   1417篇
  2015年   1955篇
  2014年   2477篇
  2013年   2280篇
  2012年   3356篇
  2011年   3442篇
  2010年   2089篇
  2009年   1702篇
  2008年   2237篇
  2007年   2142篇
  2006年   1901篇
  2005年   1899篇
  2004年   1339篇
  2003年   1270篇
  2002年   1070篇
  2001年   798篇
  2000年   729篇
  1999年   746篇
  1998年   490篇
  1997年   451篇
  1996年   327篇
  1995年   346篇
  1994年   286篇
  1993年   209篇
  1992年   253篇
  1991年   225篇
  1990年   167篇
  1989年   164篇
  1988年   153篇
  1987年   126篇
  1986年   92篇
  1985年   77篇
  1984年   33篇
  1983年   52篇
  1982年   12篇
  1981年   21篇
  1980年   15篇
  1979年   23篇
  1977年   10篇
  1974年   10篇
  1973年   12篇
  1970年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
OBJECTIVE: Tissue microarray (TMA) technology allows simultaneous examination of the expression of many molecular markers (protein, mRNA, DNA, etc.) with high-throughput. The application of this technology, to date, has been largely confined to the study of cancer. Placental pathology poses unique challenges because of the size of the organ, its complex anatomy, as well as its histological heterogeneity. The objective of this study was to assess the feasibility and efficiency of TMAs for immunohistochemistry and in situ hybridization of placental tissues. STUDY DESIGN: TMAs were constructed using an automated tissue arrayer. Standard 0.6-mm or 1-mm microarray needles were used. Villous parenchyma, basal plate, and chorioamniotic membranes were targeted in each block. Five mum-thick TMA sections underwent immunohistochemical analysis of both cytoplasmic and nuclear antigens using a panel of antibodies against a variety of cytoplasmic [cytokeratin-7, vascular endothelial growth factor (VEGF), and protein Z], membranous (endoglin), and nuclear (c-fos and c-jun) antigens. mRNA in situ hybridization for surfactant protein A (SP-A) and chromogenic in situ hybridization for the Y chromosome (DYZ1) were also performed. RESULTS: Validation of TMA immunoreactivity demonstrated comparable results with corresponding whole sections. When a two-tiered scoring system (positive/negative) was employed, there was agreement between two and three cores and whole tissue sections (kappa>0.7). When a three-tiered scoring system (negative, weak-positive, or strong-positive) was used, the data from three cores showed the highest agreement with whole tissue sections (kappa >0.7). In situ hybridization experiments for mRNA and DNA were also successful in that the signals were readily detectable. Successful transfer from the donor block to the recipient block differed according to the anatomical compartment. The transfer efficiency of villous parenchyma, basal plate, and chorioamniotic membranes were 96.9% (875/903), 76.7% (115/150), and 75.4% (224/297), respectively. CONCLUSION: TMA is a practical and effective tool for high-throughput molecular analysis of the human placenta. Duplicate and triplicate cores offer agreement with whole tissue sections for two-category distinction immunostaining. TMA also affords relevant results from in situ hybridization experiments for mRNA and DNA. The major advantages are the conservation of tissues and reagents, simultaneous comparison of molecular markers in different anatomical compartments of the placenta, and reduction of experimental error.  相似文献   
102.
先天性小肠闭锁术后肠动力功能障碍的原因探讨   总被引:4,自引:0,他引:4  
目的探讨小肠闭锁术后发生肠动力功能障碍的原因及手术切除病变肠管范围。方法对小肠闭锁手术切除小肠标本15例及对照组6例非肠道或神经系统疾病死亡的足月新生儿尸检小肠标本肠壁S-100蛋白、α-平滑肌肌动蛋白(α-SMA)和c-kit蛋白进行免疫组化研究。观察闭锁两端肠壁肠神经系统(ENS)、平滑肌和肠间质细胞(ICCs)病理改变及其分布范围,并行统计学处理。结果闭锁近端肠壁S-100、α-SMA和c—kit阳性表达明显低于对照组。随远离盲端,以上指标呈逐渐增加趋势。在闭锁近端16cm、远端4cm处,三者病变总体趋于正常。结论小肠闭锁两端肠壁与肠动力密切相关的ENS、平滑肌和ICCs均存在病变。是小肠闭锁术后发生肠道动力功能障碍的原因。在患儿小肠长度允许的情况下.切除闭锁近端肠管16cm以上,而远端切除4cm.可减少或避免术后肠动力功能障碍的发生。  相似文献   
103.
通过研究样本地区农村中医药人力资源的现状,对中医药人力资源的培训与继续教育意愿进行分析,探讨合理配置农村中医药人力资源的政策和措施,促进农村中医事业的发展,实现卫生公平.  相似文献   
104.
殷红妹  刘军 《中国药师》2005,8(10):816-818
目的:建立皮康口服液的质量标准.方法:用薄层色谱法对黄芪、赤芍进行定性鉴别,用反相高效液相色谱(RPHPLC)法测定口服液中的芍药苷的含量.结果:薄层色谱斑点清晰,专属性强;芍药苷在0.116~1.16 μg范围内呈良好的线性关系,r=0.999 8,平均回收率为98.99%,RSD为0.62%.结论:所建立的方法简便准确、灵敏度高,可用于皮康口服液的质量控制.  相似文献   
105.
106.
目的 探讨C反应蛋白与白蛋白比值(CRP/ALB)对川崎病(KD)早期丙种球蛋白(IVIG)抵抗的预测价值。方法 将2020年1月至2023年6月成都医学院第一附属医院住院的118例病程≤5 d的KD患儿分为IVIG抵抗组和IVIG敏感组,分析患儿临床资料,采用多因素Logistic回归分析探究独立危险因素,ROC曲线探究CRP/ALB对KD患儿早期IVIG抵抗的预测价值。结果 IVIG抵抗组比IVIG敏感组有更高水平的白细胞计数(WBC)、CRP、CRP/ALB和更低水平的血红蛋白(HGB)。CRP/ALB升高和HGB降低是KD患儿早期IVIG抵抗的独立危险因素。CRP/ALB可预测KD患儿早期IVIG抵抗(AUC=0.664)。结论 CRP/ALB升高和HGB降低是KD患儿早期IVIG抵抗的独立危险因素,CRP/ALB可有效预测KD患儿早期IVIG抵抗。  相似文献   
107.
Among refractive errors, astigmatism is the most common optical aberration, where refraction changes in different meridians of the eye. It causes blurred vision at any distance and includes corneal, lenticular, and retinal astigmatism. Cataract surgery used to cause a progressive increase in the pre-exisiting corneal astigmatism because of creating a surgically induced astigmatism, for example, a large size surgery incision. The development of surgical techniques during last decades has made cataract surgery interchange to treat preoperative corneal astigmatism at time of surgery. Nowadays, three surgical approaches can be used. By placing a sutureless clear corneal incision on the steep meridian of the cornea, a preoperative corneal astigmatism less than 1.0 D can be corrected. Single or paired peripheral corneal relaxing incisions (PCRIs) provide 1.0-3.0 D corneal astigmatism correction. PCRIs are typically used for treating 1.0-1.5 D of regular corneal astigmatism, if more than 2.0 D, the risk of overcorrection and irregular astigmatism is increased. When toric intraocular lenses (IOLs) are unavailable in markets, PCRIs are still a reasonable option for patients with up to 3.0 D of pre-existing corneal astigmatism. Toric IOLs implantation can correct 1.0-4.5 D of corneal astigmatism. Several IOLs are approved to correct a high degree of corneal astigmatism with cylinder power up to 12.0 D. These approaches can be used alone or in combination.  相似文献   
108.
Endoscopic mucosal resection (EMR) was originally described in 1973 and is currently a popular practice used in treating polyps, small adenomas, and early cancers. Although the safety of EMR has been proven in numerous studies, complications occur occasionally. We report a case in which the patient complained of severe upper abdominal pain and who was diagnosed with acute appendicitis after colorectal EMR. The patient recovered well after surgery. Cautious observation is necessary when resuming oral intake in patients who undergo colorectal EMR and who complain of postoperative abdominal pain. Observation is especially important for patients with a fecalith that may have originally existed in the appendix or in the colon near the appendix.  相似文献   
109.
Vitamin D (VD) is a major regulator of calcium metabolism in many living organisms. In addition, VD plays a key role in regulating innate and adaptive immunity in vertebrates. Neutrophils constitute an important part of the first line of defense against invading microbes; however, the potential effect of VD on neutrophils remains elusive. Thus, in this study zebrafish in different developmental stages were utilized to identify the potential role of VD in the basal homeostasis and functions of neutrophils. Our results showed that addition of exogenous VD<sub>3</sub> promoted granulopoiesis in zebrafish larvae. Reciprocally, neutrophil abundance in the intestine of adult zebrafish with a cyp2r1 mutant, lacking the capacity to 25-hydroxylate VD, was reduced. Moreover, VD-mediated granulopoiesis was still observed in gnotobiotic zebrafish larvae, indicating that VD regulates neutrophil generation independent of the microbiota during early development. In contrast, VD was incapable to influence granulopoiesis in adult zebrafish when the commensal bacteria were depleted by antibiotic treatment, suggesting that VD might modulate neutrophil activity via different mechanisms depending on the developmental stage. In addition, we found that VD<sub>3</sub> augmented the expression of il-8 and neutrophil recruitment to the site of caudal fin amputation. Finally, VD<sub>3</sub> treatment significantly decreased bacterial counts and mortality in zebrafish infected with Edwardsiella tarda (E. tarda) in a neutrophil-dependent manner. Combined, these findings demonstrate that VD regulates granulopoiesis and neutrophil function in zebrafish immunity.  相似文献   
110.
Aims dl‐PHPB (potassium 2‐(1‐hydroxypentyl)‐benzoate) has been shown to have neuroprotective effects against acute cerebral ischemia, vascular dementia, and Alzheimer''s disease. The aim of this study was to investigate the effects of dl‐PHPB on memory deficits and preliminarily explore the underlying molecular mechanism.MethodsBlood glucose and behavioral performance were evaluated in the KK‐Ay diabetic mouse model before and after dl‐PHPB administration. Two‐dimensional difference gel electrophoresis (2D‐DIGE)‐based proteomics was used to identify differentially expressed proteins in brain tissue. Western blotting was used to study the molecular mechanism of the related signaling pathways.ResultsThree‐month‐old KK‐Ay mice were given 150 mg/kg dl‐PHPB by oral gavage for 2 months, which produced no effect on the level of serum glucose. In the Morris water maze test, KK‐Ay mice treated with dl‐PHPB showed significant improvements in spatial learning and memory deficits compared with vehicle‐treated KK‐Ay mice. Additionally, we performed 2D‐DIGE to compare brain proteomes of 5‐month KK‐Ay mice treated with and without dl‐PHPB. We found 14 altered proteins in the cortex and 11 in the hippocampus; two of the 25 altered proteins and another four proteins that were identified in a previous study on KK‐Ay mice were then validated by western blot to further confirm whether dl‐PHPB can reverse the expression levels of these proteins. The phosphoinositide 3‐kinase/protein kinase B/glycogen synthase kinase‐3β (PI3K/Akt/GSK‐3β) signaling pathway was also changed in KK‐Ay mice and dl‐PHPB treatment could reverse it.ConclusionsThese results indicate that dl‐PHPB may play a potential role in diabetes‐associated cognitive impairment through PI3K/Akt/GSK‐3β signaling pathway and the differentially expressed proteins may become putative therapeutic targets.  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