全文获取类型
收费全文 | 19378篇 |
免费 | 1429篇 |
国内免费 | 906篇 |
专业分类
耳鼻咽喉 | 40篇 |
儿科学 | 203篇 |
妇产科学 | 106篇 |
基础医学 | 1382篇 |
口腔科学 | 256篇 |
临床医学 | 1313篇 |
内科学 | 1496篇 |
皮肤病学 | 228篇 |
神经病学 | 540篇 |
特种医学 | 589篇 |
外国民族医学 | 4篇 |
外科学 | 485篇 |
综合类 | 3359篇 |
预防医学 | 1866篇 |
眼科学 | 178篇 |
药学 | 6854篇 |
5篇 | |
中国医学 | 2218篇 |
肿瘤学 | 591篇 |
出版年
2024年 | 49篇 |
2023年 | 239篇 |
2022年 | 536篇 |
2021年 | 752篇 |
2020年 | 641篇 |
2019年 | 555篇 |
2018年 | 500篇 |
2017年 | 547篇 |
2016年 | 614篇 |
2015年 | 680篇 |
2014年 | 1220篇 |
2013年 | 1219篇 |
2012年 | 1368篇 |
2011年 | 1519篇 |
2010年 | 1205篇 |
2009年 | 980篇 |
2008年 | 1035篇 |
2007年 | 1115篇 |
2006年 | 957篇 |
2005年 | 821篇 |
2004年 | 672篇 |
2003年 | 552篇 |
2002年 | 425篇 |
2001年 | 362篇 |
2000年 | 358篇 |
1999年 | 267篇 |
1998年 | 214篇 |
1997年 | 236篇 |
1996年 | 163篇 |
1995年 | 161篇 |
1994年 | 158篇 |
1993年 | 114篇 |
1992年 | 118篇 |
1991年 | 166篇 |
1990年 | 133篇 |
1989年 | 107篇 |
1988年 | 120篇 |
1987年 | 95篇 |
1986年 | 88篇 |
1985年 | 137篇 |
1984年 | 143篇 |
1983年 | 118篇 |
1982年 | 79篇 |
1981年 | 51篇 |
1980年 | 31篇 |
1979年 | 37篇 |
1978年 | 21篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Han-Ju Chien Yi-Chun Ma Yi-Feng Zheng Cheng-Yu Kuo Wei-Chen Wang Guor-Rong Her Chien-Chen Lai 《Yao wu shi pin fen xi = Journal of food and drug analysis.》2021,29(4):738
A strategy was proposed to analyze bovine milk oligosaccharides using p-aminobenzoic ethyl ester (ABEE) closed-ring labeling and C18 capillary liquid chromatography negative ion electrospray tandem mass spectrometry. Linkage specific fragment ions were used to identify oligosaccharide isomers. By constructing the mass chromatograms using linkage specific fragment ions, isomers were differentiated based on m/z values as well as temporal separation provided by liquid chromatography. In addition to disialyllactose and the single isomer lacto-N-neohexaose, four pairs of linkage isomers including 3′/6′-sialyllactose (3′/6′-SL), 3′/6′-sialyllactosamine (3′/6′-SLN), 3′/6′-sialylgalactosyl-lactose (3′/6′-SGL), and lacto-N-tetraose/lacto-N-neotetraose (LNT/LNnT) in bovine milk were investigated. Variations of bovine milk oligosaccharides in a lactation period of 72 h after calving were studied. Sialylated oligosaccharide was found to be distinctively more abundant in milk of the first 24 h, decreasing in successive milkings. For the first time, the variation of lacto-N-tetraose in bovine milk was reported. 相似文献
972.
目的分析南京地区新生儿遗传代谢病的检出情况。方法分析2013年12月至2018年7月南京市出生的175767例串联质谱新生儿筛查的结果。采用非衍生化串联质谱技术检测干血滤纸片氨基酸、酰基肉碱和琥珀酰丙酮浓度,筛查新生儿氨基酸、有机酸和脂肪酸等三大类遗传代谢病。对于筛查阳性的患儿,通过基于高通量测序技术的基因Panel检测致病基因突变。对数据采用描述性统计学方法进行分析。结果175767例新生儿筛查初筛阳性率为2.1%(3691/175767),3691例初筛阳性中召回3598例,最终临床诊断遗传代谢病患儿62例,包括氨基酸代谢病35例、有机酸代谢病12例、脂肪酸代谢病15例。本地区新生儿遗传代谢病的总发病率为0.0353%,其中氨基酸代谢病、有机酸代谢病和脂肪酸代谢病的总发病率分别为0.0199%、0.0068%和0.0085%。发病率最高的疾病分别为苯丙氨酸羟化酶缺乏症0.0159%、甲基丙二酸血症0.0051%和原发性肉碱缺乏症0.0051%。62例临床诊断为遗传代谢病的患儿中,51例(82.2%,包括17例苯丙氨酸羟化酶缺乏症和34例其他遗传代谢病)进行了基因诊断(另外11例苯丙氨酸羟化酶缺乏症患儿拒绝进行基因诊断)。17例苯丙氨酸羟化酶缺乏症患儿均找到2个致病突变,分别来自于父母。34例其他遗传代谢病患儿中29例找到2个致病突变,分别来自于父母;另5例患儿仅找到1个致病突变,其中2例高甲硫氨酸血症为常染色体显性遗传。结论本地区发病率较高的新生儿遗传代谢病为苯丙氨酸羟化酶缺乏症、甲基丙二酸血症和原发性肉碱缺乏症。串联质谱筛查出的部分病例仅表现为筛查指标异常,随访中尚未出现特异性临床症状,需要进行更长期的随访。 相似文献
973.
目的 探讨脑小血管病(CSVD)患者血液氨基酸谱和脂肪酸谱的变化。方法 采用病例对照设计方法,选择2017年1月-2019年3月本院神经内科住院的165例CSVD患者为观察组,同期住院的66例非脑血管病患者作为对照组,采用串联质谱法(MS)测定入组患者血液氨基酸谱和脂肪酸谱。结果(1)2组Ala,Cys,Gly,C12,C16:1-OH,Gly/Ala,C2/C0,C3/C0,C3/C16,C6DC水平有显著性差异(P<0.05);(2)对上述代谢物进行Logistic回归分析显示Ala,Gly,Gly/Ala是CSVD发病的相关危险因素(P<0.05),C3/C0是CSVD的独立危险因素。结论 Ala,Cys,Gly,C12,C16:1-OH,Gly/Ala,C2/C0,C3/C0,C3/C16,C6DC是CSVD的潜在代谢物; Ala,Gly,Gly/Ala,C3/C0对CSVD可能具有辅助诊断价值。 相似文献
974.
975.
Akanksha Khandelwal Rajeev Kumar Seam Manish Gupta Manjit Kaur Rana Hridayesh Prakash Karen M. Vasquez Aklank Jain 《Cancer science》2020,111(3):826-839
Despite the availability of various diagnostic procedures, a tissue biopsy is still indispensable for the routine diagnosis of lung cancer. However, inaccurate diagnoses can occur, leading to inefficient cancer management. In this context, use of circulating microRNAs (miRNAs) may serve as diagnostic tools as liquid biopsies, and as biomarkers to better understand the molecular mechanisms involved in the progression of cancer. We identified miR‐590‐5p as a potential prognostic marker in the progression of non‐small cell lung cancer (NSCLC). We were able to detect this miRNA in blood plasma samples of NSCLC patients through quantitative real‐time PCR. Our data showed an ~7.5‐fold downregulation of miR‐590‐5p in NSCLC patients compared to healthy controls, which correlated with several clinicopathological features. Further, overexpression of miR‐590‐5p led to decreased cell viability, proliferation, colony formation, migration, and invasion potential of lung cancer cells, whereas its knockdown showed the opposite effect. In addition, the levels of several proteins involved in the epithelial‐to‐mesenchymal transition negatively correlated with miR‐590‐5p levels in lung adenocarcinoma cells and tumors of NSCLC patients. Further, dual‐luciferase reporter assays identified STAT3 as a direct target of miR‐590‐5p, which negatively regulated STAT3 activation and its downstream signaling molecules (eg, Cyclin D1, c‐Myc, Vimentin, and β‐catenin) involved in tumorigenesis. Taken together, our study suggests that miR‐590‐5p functions as a tumor suppressor in NSCLC through regulating the STAT3 pathway, and may serve as a useful biomarker for the diagnosis/prognosis of NSCLC, and as a potential therapeutic target for the treatment of NSCLC. 相似文献
976.
血府逐瘀口服液对大鼠缺氧-再给氧损伤心脏微血管内皮细胞黏附分子表达的影响 总被引:1,自引:0,他引:1
目的 观察血府逐瘀口服液对心脏微血管内皮细胞缺氧/复氧损伤中黏附分子表达的影响。方法 通过心脏微血管内皮细胞体外培养技术,建立缺氧/复氧损伤模型,模拟心肌缺血再灌注损伤。用免疫细胞化学法和图像定量分析系统,观察心脏微血管内皮细胞的细胞间黏附分子-1(ICAM-1)和血管细胞黏附分子-1(VCAM-1)的表达变化。结果大鼠心脏微血管内皮细胞缺氧4h后ICAM-1和VCAM-1的蛋白表达较对照组升高,但无统计学意义(P〉0.05),再给氧6h、12h后ICAM-1和VCAM一1的表达较对照组明显增高(P〈0.01)。血府逐瘀口服液能显著降低ICAM-1和VCAM-1的蛋白表达,这种作用随着剂量的增加而增强。结论 血府逐瘀口服液可通过降低心脏微血管内皮细胞的ICAM-1和VCAM-1表达,减少白细胞浸润,从而减轻缺血再灌注损伤中的炎性反应对心功能造成损害。 相似文献
977.
目的原核表达斯氏按蚊TEP1蛋白。方法PCR方法从斯氏按蚊扩增TEP1基因,并插入原核表达载体pQE-80L,构建重组表达质粒pQE-80L/TEP1。转化DH5α菌,IPTG诱导表达融合蛋白及质谱鉴定。结果成功表达重组质粒,经过质谱鉴定为斯氏按蚊TEP1分子。结论成功表达了按蚊TEP1蛋白为后续的抗体制备及TEP1功能研究奠定了基础。 相似文献
978.
Hong-Xu Liu Yu Li Xue-Dong Jiang Hong-Nian Yin Lin Zhang Yu Wang Jun Yang 《World journal of gastroenterology : WJG》2006,12(33):5281-5286
AIM: To shed light on the possible role of mismatch repair gene Mlh3 in familial esophageal cancer (FEC).METHODS: A total of 66 members from 10 families suggestive of a genetic predisposition to hereditary esophageal cancer were screened for germline mutations in Mlh3 with denaturing high performance liquid chromatography (DHPLC), a newly developed method of comparative sequencing based on heteroduplex detection. For all samples exhibiting abnormal DHPLC profiles,sequence changes were evaluated by cycle sequencing.For any mutation in family members, we conducted a segregation study to compare its prevalence in sporadic esophageal cancer patients and normal controls.RESULTS: Exons of Mlh3 in all samples were successfully examined. Overall, 4 missense mutations and 3 polymorphisms were identified in 4 families. Mlh3 missense mutations in families 9 and 10 might be pathogenic, but had a reduced penetrance. While in families 1 and 7,there was no sufficient evidence supporting the monogenic explanations of esophageal cancers in families.The mutations were found in 33% of high-risk families and 50% of low-risk families.CONCLUSION: Mlh3 is a high risk gene with a reduced penetrance in some families. However, it acts as a low risk gene for esophageal cancer in most families. Mutations of Mlh3 may work together with other genes in an accumulated manner and result in an increased risk of esophageal tumor. DHPLC is a robust and sensitive technique for screening gene mutations. 相似文献
979.
目的比较并评价两种基质辅助激光解吸电离飞行时间质谱(matrix-assisted laser desorption ionization time of flight mass spectrometry,MALDI-TOF-MS)系统——Bruker MALDI Biotyper系统(以下简称Bruker Biotyper系统)和MALDITOF Vitek MS系统(以下简称Vitek MS系统)在革兰阴性菌临床分离株鉴定中的应用。方法收集沈阳军区总医院2012年3月—2013年1月分离自血液、尿液、脑脊液、分泌物、伤口拭子和痰液临床标本的革兰阴性菌共120株。应用Vitek 2 Compact生化鉴定系统将每株细菌鉴定到种,而后采用Bruker Biotyper和Vitek MS系统对其进行鉴定,三者鉴定结果存在差异的菌株经16S rDNA测序最终确认菌种。结果对于120株革兰阴性菌临床分离株,Bruker Biotyper和Vitek MS系统在属的水平上正确鉴定率分别为95.0%和92.5%,在种的水平上正确鉴定率分别为89.2%和86.7%,差异均无统计学意义。结论 Bruker Biotyper和Vitek MS系统对革兰阴性菌临床分离株的正确鉴定率不存在差异,两种系统的鉴定结果与各自的图谱数据库有密切关系。 相似文献
980.