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   79214篇
  免费   6898篇
  国内免费   4557篇
耳鼻咽喉   926篇
儿科学   963篇
妇产科学   809篇
基础医学   9840篇
口腔科学   1379篇
临床医学   8705篇
内科学   11521篇
皮肤病学   1413篇
神经病学   3936篇
特种医学   3909篇
外国民族医学   21篇
外科学   7976篇
综合类   12070篇
现状与发展   28篇
一般理论   7篇
预防医学   5360篇
眼科学   2351篇
药学   8646篇
  67篇
中国医学   3943篇
肿瘤学   6799篇
  2024年   189篇
  2023年   978篇
  2022年   2475篇
  2021年   3452篇
  2020年   2487篇
  2019年   2284篇
  2018年   2459篇
  2017年   2328篇
  2016年   2465篇
  2015年   3694篇
  2014年   4576篇
  2013年   4533篇
  2012年   6633篇
  2011年   7036篇
  2010年   4648篇
  2009年   4005篇
  2008年   4996篇
  2007年   4699篇
  2006年   4448篇
  2005年   3924篇
  2004年   2963篇
  2003年   2965篇
  2002年   2473篇
  2001年   1679篇
  2000年   1404篇
  1999年   1253篇
  1998年   791篇
  1997年   703篇
  1996年   599篇
  1995年   544篇
  1994年   520篇
  1993年   345篇
  1992年   374篇
  1991年   343篇
  1990年   288篇
  1989年   262篇
  1988年   174篇
  1987年   188篇
  1986年   141篇
  1985年   96篇
  1984年   55篇
  1983年   39篇
  1982年   38篇
  1981年   27篇
  1980年   27篇
  1979年   16篇
  1978年   6篇
  1975年   7篇
  1973年   10篇
  1972年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
目的探讨急性坏死性胰腺炎(ANP)大鼠模型胰腺组织高迁移率族蛋白-1(HMGB1)的表达及其意义。方法72只大鼠随机分成3组,即对照组、ANP组和正丁酸钠治疗组(治疗组)。逆行性胰胆管注射5%牛磺胆酸钠建立ANP模型。ELISA法检测血清TNF-α和IL-1β水平;RT-PCR法检测胰腺组织HMGB1 mRNA的表达,并观察其病理变化。结果ANP组血清TNF-α和IL-1β水平在ANP建模后6h达高峰,12h下降。ANP组大鼠胰腺组织HMGB1 mRNA表达水平在ANP后12h明显升高,至24h仍维持在较高水平。治疗组胰腺组织HMGB1 mRNA表达水平在ANP后12,24h明显低于ANP组(P<0.05),且同期胰腺损伤比ANP组轻(P<0.05)。建模后24h血清TNF-α和IL-1β水平ANP组与治疗组间差异无显著性。结论HMGB1作为晚期炎症因子参与了ANP的全身炎症反应。HMGB1抑制剂正丁酸钠能降低ANP大鼠胰腺组织HMGB1基因表达水平,减轻ANP胰腺组织的损伤。  相似文献   
992.
目的:制备盐酸氯丙嗪生物黏附缓释片,并对该缓释片进行体外释放性能和黏附性评价。方法:建立释放度紫外分析方法与黏附力测定方法。采用粉末直接压片压制盐酸氯丙嗪黏附缓释片,采用正交试验以释放度为指标,筛选最优处方。按照上述筛选出的最优处方制备盐酸氯丙嗪黏附缓释片,进行体外释放度与黏附力综合评价。结果:盐酸氯丙嗪黏附缓释片的释放度在1,4,8,12 h释放度分别是23.45%,57.89%,79.56%,95.21%。生物黏附缓释片在胃和肠黏附力分别为30.4 g·cm-2和49.4 g·cm-2,均大于普通片,且与肠的黏附力大于胃。结论:盐酸氯丙嗪生物黏附缓释片在12 h内累积释放度为95%左右,与胃肠黏膜有较大的黏附力,能满足生物黏附制剂的要求。  相似文献   
993.
[目的]建立舒血宁注射液中总黄酮醇苷含量测定方法,为其质量控制提供技术手段。[方法]采用ExtendC18柱(4.6 mm×250 mm,5μm),以乙腈-0.1%甲酸水(v/v)为流动相,梯度洗脱,流速为1 mL/min,进样体积为15μL,柱温为35℃,检测波长为360 nm。[结果]槲皮素、山奈酚及异鼠李素3种黄酮的分离及线性关系良好;精密度,重复性和稳定性RSD均都小于5%;平均回收率在99.5%~100%之间且RSD均值小于5%。30批舒血宁注射液中总黄酮醇苷平均含量为1.06 mg/mL且无统计学差异。[结论]本方法简便、准确、可靠,适用于舒血宁注射液中总黄酮醇苷含量的测定,为舒血宁注射液质量控制提供了科学依据。  相似文献   
994.
PURPOSE: To investigate ocular higher order aberration (HOA) changes caused by rigid gas permeable (RGP) contact lens (CL) wear. METHODS: Twenty-two eyes of 22 myopic patients and 14 eyes of 14 keratoconic patients who were fitted with an RGP CL were enrolled to examine ocular HOAs using a Hartmann-Shack wavefront sensor before and after RGP wear. Root mean square (RMS) values and Zernike coefficients in RGP-on and RGP-off eyes were compared for both myopic and keratoconic eyes, or between patient groups divided according to their prefitted total HOA value (RMS<0.33 microm or>or=0.33 microm in myopic eyes and RMS<0.46 microm or>or=0.46 microm in keratoconic eyes). All HOA values were recomputed for a 4-mm pupil for comparison purposes. RESULTS: In keratoconic eyes, RGP CL changed the direction of vertical coma from -0.185 to 0.134 microm (p=0.024). In the low HOA myopic group, total HOA increased from 0.23 to 0.35 microm (p=0.006) by RGP CL wear, mainly due to increased coma aberration from 0.0951 to 0.2146 microm (p=0.006). The direction of vertical coma changed from the inferior to superior cornea in the low HOA group (p=0.020). In the high HOA keratoconic group, total HOA decreased from 0.54 to 0.36 microm (p=0.049), and the direction of the vertical coma changed from the inferior to superior cornea (p=0.049). CONCLUSIONS: RGP CL wear may enhance or reduce HOA based on original existing ocular aberration mainly through directional changes in vertical coma.  相似文献   
995.
PURPOSE: To detect the abnormalities of the optic radiation (OR) in children with amblyopia by diffusion tensor imaging (DTI) and tractography. DESIGN: Prospective, nonrandomized clinical trial. METHODS: Fourteen children with amblyopia and 14 normally sighted children underwent DTI scanning. After the ORs were reconstructed by using tractography algorithm, voxels through which the anterior parts of ORs passed were determined for their values of fractional anisotropy (FA). The paired t test was applied to compare their mean FA values of right OR and left OR in the control group. For the amblyopia group, analysis of variance was conducted to determine the effect of laterality and vision status on the FA values. In addition, the voxel numbers of anterior and posterior parts of both ORs were calculated. The Student t test was used to compare the average FA of bilateral ORs and voxel numbers between the two groups. RESULTS: Comparison demonstrated left-higher-than-right asymmetry in both amblyopic children and normal children. We found no significant difference of average FA between the amblyopic group (0.4832 +/- 0.0225) and control group (0.4770 +/- 0.0273). Voxel numbers of the anterior parts of both ORs were not significantly different between the two groups, whereas voxel numbers of their posterior parts in the controls were more than that of amblyopic children. CONCLUSION: Tractography showed more voxels in the posterior ORs of normal children than in the amblyopic children, indicating that normal children have better development of the ORs. The underdevelopment of the ORs might reflect the dysfunction of visual cortex in children with amblyopia.  相似文献   
996.
Protective effect of uridine on cornea in a rabbit dry eye model   总被引:1,自引:0,他引:1  
PURPOSE: To investigate the effect of uridine on cultured human corneal epithelial cells and keratocytes in vitro and to evaluate whether the application of uridine-containing eye drops could improve ocular surface health in an in vivo dry eye model. METHODS: Uridine was added to cultured epithelial cells (3 x 10(4) cells/well) and keratocytes (1 x 10(4) cells/well) at various concentrations (0.5-50 microM). Cytotoxicity was tested with the use of MTT assay, and the cells were assessed for apoptosis with the use of flow cytometry. Expressions of hyaluronic acid (HA), glycosaminoglycan (GAG), nitric oxide (NO), and matrix metalloproteinase (MMP)-9 were measured. In vivo, the degree of reepithelialization was assessed after topical application of uridine (100 microM) in a rabbit corneal wound model. Changes in tear production and conjunctival goblet cell counts were investigated after instillation of various concentrations of uridine-containing eye drops in a rabbit dry eye model. RESULTS: In vitro, uridine showed no cellular toxicity. It increased the biosynthesis of HA and GAG and reduced MMP-9 levels in cultured corneal epithelial cells and keratocytes. In vivo, uridine enhanced corneal wound healing and significantly increased the number of conjunctival goblet cells in rabbits. CONCLUSIONS: Uridine can restore the health of the ocular surface in a rabbit corneal wound and dry eye model.  相似文献   
997.
998.
正交实验法评估伊曲康唑对甲真菌病的疗效   总被引:3,自引:1,他引:3  
为了观察伊曲康唑治疗甲真菌病各种方法的疗效,探索服用该药的最低剂量和最佳治疗方案应用正交实验法观察46例服用伊曲康唑的甲真菌病患者。结果显示:在4个观察组(100mg每日1次,连续口服;100mg,每日2次,隔周口服;200mg,每日1次,隔周口服;200mg,每日2次,每月服用1周)中,指甲时间最短的方法是:200mg每日1次,隔周口服(平均治愈时间3.11个月);趾甲癣治疗时间最短的是:100  相似文献   
999.
1000.
气管食管裂隙状瘘发音重建术的声学分析   总被引:4,自引:0,他引:4  
目的 客观评价气管食管裂隙状瘘发音重建术后的发音效果,并以此指导临床工作。方法 对喉全切除术后I期与Ⅱ期气管食管裂隙状瘘发音患者、食管发音患者、安装Blom—Singer发音钮患者以及健康人分别进行语音测试,分析7项客观声学参数,比较发音效果。结果 经统计学t检验,气管食管裂隙状瘘语音最长发音时间短于健康人,明显长于食管音,但和Blom—Singer发音钮语音差异无显著性;其声音的强度和健康人及Blom—Singer发音钮差异无显著性,明显高于食管音;其基频明显低于健康人;其频率微扰和振幅微扰明显高于健康人,而明显低于食管发音,与Blom—Singer发音钮语音差异无显著性;其共振峰频率和能量仅在F1共振峰能量上明显高于食管音,其余各频率上差异均无显著性。虽然喉全切除I期气管食管裂隙状瘘发音重建术中制作帽状气室,而Ⅱ期发音重建术中不制作帽状气室,但两者语音声学分析各参数间差异均无显著性。结论气管食管瘘语音比食管音接近健康人语音,能满足日常生活需要。气管食管裂隙状瘘发音重建术中不制作帽状气室不影响术后的发音。  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