全文获取类型
收费全文 | 18170篇 |
免费 | 2032篇 |
国内免费 | 772篇 |
专业分类
耳鼻咽喉 | 47篇 |
儿科学 | 247篇 |
妇产科学 | 114篇 |
基础医学 | 3285篇 |
口腔科学 | 224篇 |
临床医学 | 1316篇 |
内科学 | 3206篇 |
皮肤病学 | 197篇 |
神经病学 | 879篇 |
特种医学 | 350篇 |
外国民族医学 | 4篇 |
外科学 | 1033篇 |
综合类 | 2250篇 |
现状与发展 | 5篇 |
预防医学 | 1072篇 |
眼科学 | 178篇 |
药学 | 3351篇 |
8篇 | |
中国医学 | 1157篇 |
肿瘤学 | 2051篇 |
出版年
2024年 | 248篇 |
2023年 | 528篇 |
2022年 | 929篇 |
2021年 | 1081篇 |
2020年 | 909篇 |
2019年 | 833篇 |
2018年 | 730篇 |
2017年 | 755篇 |
2016年 | 827篇 |
2015年 | 917篇 |
2014年 | 1202篇 |
2013年 | 1447篇 |
2012年 | 1056篇 |
2011年 | 989篇 |
2010年 | 805篇 |
2009年 | 738篇 |
2008年 | 777篇 |
2007年 | 704篇 |
2006年 | 616篇 |
2005年 | 617篇 |
2004年 | 477篇 |
2003年 | 504篇 |
2002年 | 434篇 |
2001年 | 390篇 |
2000年 | 278篇 |
1999年 | 247篇 |
1998年 | 247篇 |
1997年 | 210篇 |
1996年 | 177篇 |
1995年 | 143篇 |
1994年 | 142篇 |
1993年 | 127篇 |
1992年 | 113篇 |
1991年 | 96篇 |
1990年 | 86篇 |
1989年 | 67篇 |
1988年 | 52篇 |
1987年 | 64篇 |
1986年 | 47篇 |
1985年 | 82篇 |
1984年 | 62篇 |
1983年 | 57篇 |
1982年 | 46篇 |
1981年 | 39篇 |
1980年 | 21篇 |
1979年 | 25篇 |
1978年 | 10篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
低分子壳聚糖季铵盐对小鼠实体瘤及其免疫系统的影响 总被引:11,自引:1,他引:11
目的研究低分子壳聚糖季铵盐对小鼠S180 和机体免疫功能的影响。方法采用抑瘤实验、碳粒廓清实验、MTT法观察低分子壳聚糖季铵盐对小鼠实体瘤和免疫系统的影响。结果低分子壳聚糖季铵盐可使荷瘤小鼠的碳粒廓清指数、胸腺指数、脾脏指数升高,并对由ConA、脂多糖诱导体外小鼠T ,B淋巴细胞增殖有明显的兴奋作用;能够抑制小鼠实体瘤的生长。结论低分子壳聚糖季铵盐能够增强机体的免疫功能,并具有抑瘤作用 相似文献
62.
Buyang Huanwu decoction (BYHWD), as one of the traditional Chinese medicine formulas, is widely used in the clinical treatment of lumbar disc herniation (LDH) with curative effect. It has the characteristics of multi-component, multi-target, and mutual synergy, but the mechanism of action is often unclear. It needs some research to explore the molecular mechanism of BYHWD in the treatment of LDH based on network pharmacology and molecular docking. Screen the active compounds of BYHWD and predict drug-related gene/protein targets, which could determine the specific target of BYHWD in the treatment of LDH. Construct the “Drugs-Compounds-Targets” network and search for the core targets. Use Gene Ontology functional enrichment analysis, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, and molecular docking verification to explore the possible molecular mechanism. Eighty-two effective compounds and 666 targets of BYHWD, 187 targets for LDH treatment, and 20 core candidate targets were excavated. A total of 3414 entries were identified by Gene Ontology enrichment analysis, 173 related signal pathways were identified by Kyoto Encyclopedia of Genes and Genomes enrichment analysis, and 5 core compounds were identified by molecular docking, which had a good affinity with core genes STAT3, JUN, AKT1, MAPK1, RELA, and PIK3CA. BYHWD may play the role of analgesic and improving function by synergistic anti-inflammatory and analgesic compounds, regulating cell metabolic differentiation, regulating immunity, and anticoagulation. BYHWD in the treatment of LDH may play a role in analgesia and improve function through multiple signaling pathways, including PI3K-Akt, mitogen-activated protein kinase, tumor necrosis factor, and interleukin-17. The PI3K-Akt signaling may be one of the key mechanisms. 相似文献
63.
人内质网分子伴侣BiP的克隆、表达及其在RA患者血清抗体检测中的作用 总被引:1,自引:0,他引:1
以类风湿关节炎(rheumatoid arthritis,RA)患者滑膜组织文库cDNA为模板,用PCR方法扩增得到1965 bp人内质网分子伴侣BiP的全长cDNA,将其克隆入OmicsLinkTM表达载体pReceiver-B01a,构建重组表达质粒pReceiver-B01a-BiP。重组表达质粒导入大肠杆菌BL-21(DE3)菌株中诱导表达目的蛋白,表达产物以Ni+-NTA agarose层析柱纯化。SDS-PAGE和免疫印迹法(Western blot)分析发现,表达产物以可溶性蛋白和包涵体形式共同存在,表达量约占菌体蛋白总量的20%~30%。相对分子质量约为80000,纯度达到电泳级。经免疫印迹法鉴定,获得的BiP重组蛋白可以与RA患者血清反应,检测的抗BiP抗体在RA患者血清中的阳性率为75.4%(49/65),明显高于系统性红斑狼疮(systemic lupus erythe-matosus,SLE)患者14.6%(7/48)、原发性干燥综合征(primary Sj gren’s syndrome,pSS)患者7.3%(4/55)及正常人0%(0/71)(P<0.01)。表明,经原核表达获得的BiP全长蛋白,RA患者血清抗体可以很好结合,有望应用于临床血清学诊断。 相似文献
64.
65.
In this study, the phase-structure and rheological response-behavior of multi-walled carbon nanotube (MWCNTs) modified asphalt-binder (MWCNTs-MA) were measured and quantified in the laboratory. The changes in the molecular dynamics due to MWCNTs modification were simulated and quantified based on the intermolecular interaction energy computations, electrostatic potential surface analyses and phase-structure modeling of the asphalt-binder matrix. The rheological properties such as the asphalt-binder viscosity and complex modulus, of both the base and modified asphalt-binders, were determined using the standard Brookfield viscometer (BV) and dynamic shear rheology (DSR) test devices, respectively. In comparison to the base asphalt-binder, the corresponding BV-DSR test results exhibited higher viscosity and complex modulus for the MWCNTs modified asphalt-binder, with reduced sensitivity and susceptibility to temperature variations. From the study results, it was observed that MWCNTs significantly improved the rheological properties and high-temperature performance of the asphalt-binder. Overall, the study has demonstrated that MWCNT modified asphalt-binder has great promising potential for application and usage as a road-pavement material, particularly with respect to mitigating the high temperature related distresses such as rutting. 相似文献
66.
67.
Resveratrol (3,5,4′-trans-trihydroxystilbene) is a polyphenolic phytoalexin belonging to the stilbene family. It is commonly found in grape skins and seeds, as well as other plant-based foods. Oxidative stress and inflammation play a key role in the initiation and progression of age-related eye disorders (glaucoma, cataracts, diabetic retinopathy, and macular degeneration) that lead to a progressive loss of vision and blindness. Even though the way resveratrol affects the human body and the course of many diseases is still the subject of ongoing scientific research, it has been shown that the broad spectrum of anti-inflammatory and neuroprotective properties of resveratrol has a beneficial effect on eye tissues. In our research, we decided to analyze the current scientific literature on resveratrol, its possible mechanisms of action, and its therapeutic application in order to assess its effectiveness in eye diseases. 相似文献
68.
目的:采用分子吸收光度法测定万寿菊中代森锰锌残留。方法:通过蒸馏和溶液吸收实验装置,氯化亚锡催化,二乙基二硫代氨基甲酸钠分解定量产生二硫化碳气体,通过浓硫酸脱氧脱水,氢氧化钾的甲醇液吸收,用分光光度法在304 nm波长处测定其标准曲线。代森锰锌以平均相对分子质量333计,可通过平均相对分子质量计算出代谢锰锌的含量。结果:万寿菊中添加浓度为10 mg.kg-1和20 mg.kg-1(以二硫化碳计)的回收率(n=5)分别为95.9%和93.2%,RSD分别为4.8%和3.7%;最低检测限为2 mg.kg-1。结论:该方法操作简单,灵敏度高,适合大批量样品的检测。 相似文献
69.
Zafar Ali Shah Khalid Khan Zafar Iqbal Tariq Masood Hassan A. Hemeg Abdur Rauf 《Annals of medicine》2022,54(1):2102
BackgroundPenicillium produces a wide range of structurally diverse metabolites with significant pharmacological impacts in medicine and agriculture. For the first time, a complete metabolome of Penicillium claviforme (P. claviforme) (FBP-DNA-1205) was studied alongside pharmacological research in this study.MethodsThe metabolic profile of P. claviforme fermented on Potato Dextrose Broth (PDB) was investigated in this work. The complete metabolomics studies of fungus were performed using GC-MS and LC-MS-QTOF techniques. An in vitro model was utilised to study the cytotoxic and antioxidant activities, while an in vivo model was employed to investigate the antinociceptive and acute toxicity activities. Molecular Operating Environment (MOE) software was used for molecular docking analysis.ResultsGC-MS study showed the presence of alkanes, fatty acids, esters, azo and alcoholic compounds. Maculosin, obtain, phalluside, quinoline, 4,4’-diaminostilbene, funaltrexamine, amobarbital, and fraxetin were among the secondary metabolites identified using the LC-MS-QTOF technique. The n-hexane fraction of P. claviforme displayed significant cytotoxic activity in vitro, with an LD50 value of 92.22 µgml−1. The antinociceptive effects in vivo were dose-dependent significantly (p < .001). Interestingly, during the 72 h of investigation, no acute toxicity was demonstrated. In addition, a docking study of tentatively identified metabolites against the inflammatory enzyme (COX-2) supported the antinociceptive effect in an in silico model.ConclusionMetabolic profile of P. claviforme shows the presence of biologically relevant compounds in ethyl acetate extract. In addition, P. claviforme exhibits substantial antioxidant and cytotoxic activities in an in vitro model as well as antinociceptive activity in an in vivo model. The antinociceptive action is also supported by a molecular docking study. This research has opened up new possibilities in the disciplines of mycology, agriculture, and pharmaceutics.
Key messages
- The first time explored complete metabolome through GC-MS and LC-MS-QTOF.
- Both in vivo & in vitro pharmacological investigation of P. claviforme.
- In silico molecular docking of LC-MS-QTOF metabolites.
70.
目的:测定红芪多糖3(HPS-3)中4个组分的绝对分子量,相对分子质量分布,均方根旋转半径(Rg),多分散系数(Mw/Mn)等分子特征参数,以均方根旋转半径(Rg)对重均分子量(Mw)作图,计算4个组分在溶液状态的构象。方法:采用凝胶渗透色谱-多角度激光散射(GPC-MALLS)联用技术,流动相为含0.02%NaN3的0.1 mol.L-1NaNO3溶液,Ultrahydro-gelTM1000,500色谱柱串联。结果:HPS-3的4个组分中,HPS-3-C的Mw最大(1.986×105g.mol-1);其次为HPS-3-B(1.113×105 g.mol-1)和HPS-3-D(8.457×104 g.mol-1);HPS-3-A的Mw最小(1.223×104 g.mol-1),而Rg最大(55.5 nm)。HPS-3-D相对分子质量分布范围最广,Mw/Mn 2.543。在流动相中,HPS-3-A为球型构象,HPS-3-C为无规则线团构象,HPS-3-B和HPS-3-D则均为高枝化度结构。结论:为进一步研究HPS-3中4个组分分子特征与其生物活性的关系提供必要依据。 相似文献