全文获取类型
收费全文 | 17494篇 |
免费 | 2248篇 |
国内免费 | 375篇 |
专业分类
耳鼻咽喉 | 126篇 |
儿科学 | 270篇 |
妇产科学 | 164篇 |
基础医学 | 2851篇 |
口腔科学 | 233篇 |
临床医学 | 1012篇 |
内科学 | 2238篇 |
皮肤病学 | 218篇 |
神经病学 | 1330篇 |
特种医学 | 413篇 |
外国民族医学 | 1篇 |
外科学 | 1095篇 |
综合类 | 1763篇 |
预防医学 | 1913篇 |
眼科学 | 201篇 |
药学 | 2017篇 |
中国医学 | 3286篇 |
肿瘤学 | 986篇 |
出版年
2024年 | 1005篇 |
2023年 | 524篇 |
2022年 | 504篇 |
2021年 | 513篇 |
2020年 | 451篇 |
2019年 | 693篇 |
2018年 | 787篇 |
2017年 | 455篇 |
2016年 | 597篇 |
2015年 | 847篇 |
2014年 | 534篇 |
2013年 | 649篇 |
2012年 | 642篇 |
2011年 | 691篇 |
2010年 | 561篇 |
2009年 | 529篇 |
2008年 | 538篇 |
2007年 | 579篇 |
2006年 | 523篇 |
2005年 | 472篇 |
2004年 | 770篇 |
2003年 | 452篇 |
2002年 | 387篇 |
2001年 | 400篇 |
2000年 | 237篇 |
1999年 | 229篇 |
1998年 | 253篇 |
1997年 | 325篇 |
1996年 | 279篇 |
1995年 | 246篇 |
1994年 | 330篇 |
1993年 | 242篇 |
1992年 | 251篇 |
1991年 | 255篇 |
1990年 | 249篇 |
1989年 | 178篇 |
1988年 | 183篇 |
1987年 | 98篇 |
1986年 | 101篇 |
1985年 | 300篇 |
1984年 | 371篇 |
1983年 | 265篇 |
1982年 | 306篇 |
1981年 | 251篇 |
1980年 | 198篇 |
1979年 | 198篇 |
1978年 | 148篇 |
1977年 | 90篇 |
1976年 | 151篇 |
1975年 | 119篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Acquired Immunodeficiency Syndrome (AIDS) 总被引:3,自引:0,他引:3
Joel S Schuman M.D. Juan Orellana M.D. Alan H Friedman M.D. Steven A Teich M.D. 《Survey of ophthalmology》1987,31(6):384-410
The Acquired Immunodeficiency Syndrome (AIDS), caused by the human immunodeficiency virus (HIV), also called the human T-lymphotropic virus type III/lymphadenopathy-associated virus [HTLV-III/LAV], has affected over 23,000 people; more than half of those with the disease have died. The actual case fatality rate approaches 100%. AIDS affects all groups and classes of people, although some are at special risk. Distribution of the disease is worldwide. The illness' effects on the body are widespread; of special interest are the ophthalmologic manifestations. The eye may be infected by various viruses (cytomegalovirus, varicella-zoster virus, herpes simples virus or HIV itself), toxoplasma gondii, candida sp, cryptococcus neoformans, M. tuberculosis, or M. avium-intracellulare. Kaposi's sarcoma may affect the eye as well. Retinal vascular abnormalities (e.g., cotton-wool spots, vasculitis) are not uncommon in AIDS. The syndrome may present with neuro-ophthalmologic manifestations. No effective treatment for the illness is currently available, although several hold promise and there is hope for an AIDS vaccine. Prevention of infection through reduction of risks appears to be the only defense against AIDS at this time. 相似文献
82.
Karla ech Barabaszov Ale Slíva Gabriela Kratoov Sylva Holeov Anastasia Volodarskaja Tugrul Cetinkaya Silvie Broov Libor Kozubek Grayna Simha Martynkov 《Materials》2022,15(15)
Today, Ni-Cr steel is used for advanced applications in the high-temperature and electrical industries, medical equipment, food industry, agriculture and is applied in food and beverage packaging and kitchenware, automotive or mesh. A study of input steel powder from various stages of the recycling process intended for 3D printing was conducted. In addition to the precise evaluation of the morphology, particle size and composition of the powders used for laser 3D printing, special testing and evaluation of the heat-treated powders were carried out. Heat treatment up to 950 °C in an air atmosphere revealed the properties of powders that can appear during laser sintering. The powders in the oxidizing atmosphere change the phase composition and the original FeNiCr stainless steel changes to a two-phase system of Fe3Ni and Cr2O3, as evaluated by X-ray diffraction analysis. Observation of the morphology showed the separation of the oxidic phase in the sense of a brittle shell. The inner part of the powder particle is a porous compact core. The particle size is generally reduced due to the peeling of the oxide shell. This effect can be critical to 3D printing processing, causing defects on the printed parts, as well as reducing the usability of the precursor powder and can also change the properties of the printed part. 相似文献
83.
84.
85.
目的建立RP-HPLC法同时测定石榴皮提取物阴道泡腾片中安石榴苷和鞣花酸的方法。方法色谱柱为Phenomenex Gemini C18柱(250 mm×4.6 mm,5μm),流动相为甲醇-乙腈-0.2%三氟乙酸水溶液,梯度洗脱,体积流量为0.8 mL/min,检测波长280 nm。结果安石榴苷在0.098~0.610 mg/mL(r=0.999 1)、鞣花酸在0.011~0.060 mg/mL(r=0.999 8)有良好的线性关系;平均回收率分别为102.0%、100.4%(n=9),RSD均小于1.5%。结论本方法简便、准确、专属性强,为石榴皮提取物阴道泡腾片的质量控制建立了方法。 相似文献
86.
87.
目的 探讨罗布麻叶总黄酮的抗抑郁作用及与多巴胺能系统相关的可能机制.方法 采用经典的小鼠强迫游泳和悬尾抑郁模型,观察罗布麻叶总黄酮的抗抑郁作用.同时观察多巴胺D1受体阻滞剂SCH23390、D2受体阻滞剂舒必利对小鼠强迫游泳和悬尾试验中罗布麻叶总黄酮抗抑郁作用的影响,研究罗布麻叶总黄酮抗抑郁的作用机制.结果 罗布麻叶总黄酮具有明确的抗抑郁作用;SCH23390、舒必利与罗布麻叶总黄酮联合ig给药10 d,能明显延长悬尾小鼠累计不动时间(P<0.05).结论 罗布麻叶总黄酮的抗抑郁作用与多巴胺能系统有关. 相似文献
88.
The genus Ilex L. has been used as remedies in traditional Chinese medicine in Aquifoliaceae and beverages for thousands of years due to abundant pharmaceutical bioactivities. There are 600 species in genus Ilex L. containing various compounds such as terpenoids, saponins, glycosides, etc. Three species, I. cornuta, I. chinensis, and I. rotunda have been admitted in Chinese Pharmacopoeia 2015 to treat dyspepsia, stomatitis, and hyperactivity cough and protect the liver and kidney. Recent studies showed that several species have been daily drunk to promote human health and prevent cardiovascular diseases in the folk. Here we reviewed the genus Ilex L. in phytochemistry, ethnopharmacology, and pharmacology. 相似文献
89.
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
90.
Esra Yildirim Uzay Koc Vural Filiz Yalcin Cakir Sevil Gurgan 《Acta stomatologica Croatica》2022,56(2):120
ObjectiveThe purpose of this in vitro study was to evaluate the effects of four over-the-counter (OTC) whitening products on the microhardness, surface roughness, color, shear bond strength (SBS) and surface charecteristics of human enamel compared with a product used for dentist-supervised home whitening.Materials and methodsSeventy eight enamel specimens allocated into 6 groups (n=13): 1-Opalescence PF 10% (OP) dentist prescribed home whitening product, 2-Opalescence Go prefilled tray (PT), 3-Opalescence Whitening Toothpaste (WT), 4-Listerine Healthy White whitening mouth rinse (WMR), 5-Cavex Bite&White whitening pen (WP) and 6- no treatment (Con). The microhardness (VHN), surface roughness (Ra) and color of the specimens were measured (T0). The specimens were then subjected to whitening protocols for 14 days (T1.) followed by artificial saliva storage for 14 days (T2). The measurements were repeated at T1 and T2. The SBS test was done after the application of 35% phosphoric acid (Scotchbond Universal Etchant), followed by a universal adhesive (G-Premio Bond) and a micro hybrid/universal resin composite (Essentia) into a Teflon tube attached to the enamel surface (p<0.05). Surface morphologies of the enamel surfaces were examined by SEM. p value was set at 0.05ResultsApplication of OP, PT and WP decrased the microhardness of enamel specimens (p<0.05) whereas, no significant changes were seen in the microhardness of enamel specimens treated with WT and WMR (p>0.05). Ra values of enamel specimens increased with the application of OP, PT and WT (p<0.05); whereas no changes were observed after the applications of WMR and WP (p>0.05). OP, PT, WMR, and WP changed the color of the enamel(p<0.05). There were not any significant differences among the SBSs groups, apart from OP applied enamel specimens. OP showed the least SBS values (p=0.001). SEM observations revealed smooth enamel surfaces.ConclusionsThe whitening products affected the microhardness, surface roughness, color of enamel differently. Only OP decreased the SBS of the enamel. 相似文献