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   7774篇
  免费   687篇
  国内免费   262篇
耳鼻咽喉   44篇
儿科学   42篇
妇产科学   30篇
基础医学   862篇
口腔科学   25篇
临床医学   397篇
内科学   359篇
皮肤病学   24篇
神经病学   1896篇
特种医学   248篇
外国民族医学   2篇
外科学   905篇
综合类   656篇
预防医学   114篇
眼科学   2555篇
药学   305篇
  2篇
中国医学   202篇
肿瘤学   55篇
  2024年   27篇
  2023年   156篇
  2022年   208篇
  2021年   360篇
  2020年   323篇
  2019年   263篇
  2018年   307篇
  2017年   290篇
  2016年   285篇
  2015年   279篇
  2014年   465篇
  2013年   633篇
  2012年   370篇
  2011年   392篇
  2010年   313篇
  2009年   307篇
  2008年   367篇
  2007年   346篇
  2006年   324篇
  2005年   236篇
  2004年   201篇
  2003年   223篇
  2002年   165篇
  2001年   135篇
  2000年   127篇
  1999年   103篇
  1998年   135篇
  1997年   132篇
  1996年   110篇
  1995年   90篇
  1994年   80篇
  1993年   79篇
  1992年   66篇
  1991年   75篇
  1990年   67篇
  1989年   53篇
  1988年   51篇
  1987年   50篇
  1986年   55篇
  1985年   83篇
  1984年   69篇
  1983年   56篇
  1982年   62篇
  1981年   53篇
  1980年   39篇
  1979年   28篇
  1978年   25篇
  1977年   20篇
  1976年   13篇
  1975年   8篇
排序方式: 共有8723条查询结果,搜索用时 15 毫秒
11.
目的探讨下腰痛患者腰椎终板Modic退变、椎间盘退变及CT引导下腰椎间盘造影疼痛激发试验的相关性.方法对45例下腰痛患者常规行腰椎X线和MR检查,分别按Modic终板退变标准(0~3级)与Pearce椎间盘退变标准(Ⅰ~Ⅴ级)对终板和椎间盘进行评估.在CT引导下对45例患者中的40例(120个椎间盘)进行造影和疼痛激发试验,并按Dallas椎间盘造影分级系统(DDD)测评椎间盘退变程度.采用SPSS 11.5统计学软件分析腰椎终板Modic退变、椎间盘退变与腰椎间盘造影疼痛激发试验之间的相关性.结果40例下腰痛患者的腰椎终板Modic分级与椎间盘退变Pearce分级存在较强的相关性(Pearson x^2=43.326,P=0.000),与椎间盘造影疼痛激发试验有显著相关性(Pearson x^2=27.858,P=0.000);椎间盘退变Pearce分级与CT椎间盘造影椎间盘退变Dallas分级也呈较强的相关性.结论腰椎终板Modic退变分级与椎间盘退变Pearce分级密切相关,而与椎间盘疼痛激发试验有显著相关性,提示终板Modic退变可能是下腰痛的原因之一.  相似文献   
12.
项韧带骨化相关因素及其组织学变化   总被引:1,自引:0,他引:1  
于淼  刘忠军 《中国脊柱脊髓杂志》2006,16(8):586-588,I0001
目的:探讨脊髓型颈椎病患者项韧带骨化的相关因素及其组织学改变特点.方法:将45例脊髓型颈椎病患者根据项韧带有无骨化分为两组,观察并统计两组患者的年龄、性别组成、颈椎椎间退变和颈椎稳定性情况,对各指标与项韧带骨化的关系进行相关性分析,同时观察项韧带骨化的组织学改变.结果:统计分析表明,项韧带骨化和颈椎椎间退行性改变及颈椎不稳定之间具有相关性(P<0.05);同时还与患者年龄、性别组成有相关性(P<0.05).项韧带骨化的组织学改变以软骨内化骨为主.结论:项韧带骨化与颈椎退行性改变及颈椎椎间关节不稳定具有相关性,组织学改变以软骨内化骨为主.  相似文献   
13.
过量氟化物导致大鼠腰椎黄韧带退变与骨化   总被引:2,自引:0,他引:2  
[目的]研究氟化物在黄韧带骨化中可能的作用机理。[方法]36只雄性SD大鼠,实验组饮用含NaF(质量分数为1014)蒸馏水,分别于3个月及6个月时,检测骨密度,血清、骨组织标本中Ca、P^3+、Mg、Zn、Cu、Fe、F^-含量和血清碱性磷酸酶(ALP)活性;行大鼠腰段标本X线检查后组织病理观察。[结果]3个月实验组10只大鼠中6只出现氟斑牙:6个月实验组均出现氟斑牙,且大鼠中轴骨骨密度显著增加(P〈0.05)。X线检查,6个月实验组中有4只可见黄韧带嵴状骨化影。病理观察,3个月实验组大鼠黄韧带呈退行性改变;6个月实验组部分黄韧带骨化,骨化类型以膜内骨化为主。[结论]过量氟化物可造成SD大鼠腰椎黄韧带的退变、骨化,在黄韧带的骨化中可能起重要作用。  相似文献   
14.
The frequency and pathophysiology of freezing of gait (FoG) in atypical parkinsonism is unknown. We analysed the frequency of FoG in postmortem-confirmed atypical parkinsonian disorders (APD) comprising corticobasal degeneration (CBD), dementia with Lewy bodies (DLB), multiple system atrophy (MSA), and progressive supranuclear palsy (PSP). Sixty-six patients with pathologically confirmed APD (CBD, n = 13; DLB, n = 14; MSA, n = 15; PSP, n = 24) formed the basis for a multicenter clinicopathological study. Clinical features at first and last clinical visit were abstracted from patient records on standardized forms following strict instructions. At the first visit (median 36 months after symptom onset), 24% of APD had FoG (CBD, 8%; DLB, 21%; PSP, 25%; MSA, 40%). Logistic regression analysis showed a significant association of FoG and urinary incontinence (P = 0.04) at first visit. At last visit, 47% of APD had FoG (CBD, 25%; PSP, 53%; DLB, 54%; MSA, 54%). Clinicopathological correlation based on routine postmortem examination failed to identify a consistent neuropathological substrate of FoG. This study demonstrates that (1) FoG is common in APD, and (2) urinary incontinence is significantly associated with FoG in these disorders. Whether FoG and urinary incontinence share similar neuropathological substrates remains to be determined by future studies.  相似文献   
15.
We examined changes in the expression of glial fibrillary acidic protein (GFAP) mRNA during Wallerian degeneration in the corticospinal system of the adult Golden hamster following axotomy. GFAP is the product of a type III intermediate filament (IF) gene that is expressed specifically in mature astrocytes. A well-studied component of a complex response termed reactive astrogliosis that occurs after various types of CNS injury is the increased production of astrocytic processes filled with GFAP-containing IFs. While increased expression of GFAP during reactive astrogliosis has been well established at the protein level, little is known about whether or not changes in GFAP mRNA levels occur after CNS injury. In the present study we used in situ hybridization methods to examine this issue. A 35S-labeled mouse GFAP cDNA probe was used for in situ hybridizations of sections of the brain stem obtained 2, 7, and 14 days after unilateral transections of the corticospinal tract in the caudal medulla. Film as well as emulsion autoradiography showed a dramatic increase in GFAP mRNA labeling associated with the degenerating corticospinal tract. GFAP mRNA levels were already dramatically increased in the injured corticospinal tract by 2 days post axotomy and remained elevated at 14 days. Interestingly, in addition to the robust increase in GFAP mRNA levels specifically associated with the degenerating tract, a diffuse increase in GFAP mRNA labeling was observed throughout the grey matter of the brain stem at 2 days post-axotomy, but not after this time. Immunoblotting and immunocytochemical experiments verified that the increased GFAP mRNA levels in the degenerating corticospinal system were accompanied by an increased expression of the protein. These results demonstrate that an increase in GFAP mRNA levels occurs during Wallerian degeneration in the CNS and suggest that increased expression of the GFAP gene is a major contributor to CNS scarring that results after direct traumatic injury.  相似文献   
16.
非孕期子宫肌瘤红色变性40例分析   总被引:2,自引:0,他引:2  
目的 了解非孕期子宫肌瘤红色变性的临床特征。方法 本组回顾分析了1993年1月~2001年2月间住院手术治疗40例非孕期子宫肌瘤红色变性的临床病理特征。结果 非孕期子宫肌瘤红色变性发生率为2.3%。生育年龄多见,绝经后也可发生。有典型表现者2例,占5%,非典型下腹隐痛而无发热者7例,占17.5%,肌瘤结节局部压痛者12例,占30%,无任何症状者30例,占75%,白细胞升高占10例,25%。90%的红色变性肌瘤直径在5cm以上,77.5%为壁间肌瘤。68.6%有典型牛肉样改变,54.8%旋涡状结构存在。65%为单纯红色变性,余35%可合并其他类型变性。结论 非孕期子宫肌瘤红色变性临床过程缓和,症状不典型,易漏诊,不作为手术指征,但因子宫肌瘤往往较大,多需手术治疗。  相似文献   
17.
阐述肝豆状核变性(HLD)在药物、饮食、外科和分子生物学方面的治疗进展,介绍了HLD的药物治疗、外科治疗和分子生物学治疗中的新方法或新技术:以DMPS等为主的药物治疗仍是治疗HLD的主体方法,肝移植等是治疗HLD中的暴发性肝功能衰竭的首选方法,基因等治疗为HLD的彻底治疗提供了可能。  相似文献   
18.
45 patients with spinocerebellar degeneration (SCD) underwent through quantitative investigation of the ventricular and cisternal systems by CT scanning and threshold vibrometry in the limbs to find out whether these parameters could be used for distinguishing mainly spinal from cerebellar forms or from olivopontoce-rebellar atrophy. The increase in the vibration sense threshold and the mild atrophy in the posterior cranial fossa proved typical of spinal forms and the reverse for cerebellar forms. In olivopontocerebellar atrophy enlargement of the cisterns and dilatation of the ventricles always exceeded 85% of normal values.
Sommario 45 pazienti affetti da degenerazione spinocerebellare (SCD) sono stati sottoposti ad uno studio approfondito di esplorazione quantitativa del sistema ventricolare e cisternale alla TAC e della soglia di percezione vibratoria agli arti per valutare la possibilità di distinguere con questi parametri le forme prevalentemente spinali da quelle cerebellari o delle atrofie olivopontocerebellari. L'aumento della soglia vibratoria e la modesta atrofia in fossa posteriore è risultata tipica delle forme spinali, mentre l'inverso si verifica per le forme cerebellari. Nelle atrofie olivopontocerebellari l'allargamento delle cisterne e la dilatazione dei ventricoli supera quasi sempre l'85% rispetto ai casi normali.
  相似文献   
19.
The histological findings of the patellar cartilage were compared between cases of chondromalacia, which occurs predominantly in young persons (22 patients, average age 19.8 years) and cases of osteoarthritis, which is common among the elderly (21 patients, average age 65.4 years). The histological findings of cartilage in the chondromalacia were characterized by increased density and vigorous fibrous metaplasia of chondrocytes. These findings may be considered to represent a reactive change in the chondrocyte. Cartilage degeneration in osteoarthritis, by contrast, is regressive and presents a clearly different histological picture from that of chondromalacia patellae. We conclude that chondromalacia does not easily lead to osteoarthritis. On the other hand, the cartilage was characteristically softened, as observed by gross inspection, and showed rarefaction of the cartilage matrix. It should be noted that the change was not observed in aging, but showed a pattern of cartilage degeneration peculiar to young patients with chondromalacia patellae.  相似文献   
20.
探刊干性型老年黄斑变性(age-related macular deganeration,AMD)的病变发展特征并 寻找监测AMD病情进展的较敏感指标。 方法:用眼底彩色照相和眼底荧光血管造影(FFA)、明视视网膜电囤(ERG)、FM100-hue 色彩试验及视力检查,对60例(111眼)50~80岁、视力≤1.0的干性型AMD患者进行3~74个月(平均30.2个月)的随访观察。 结果:本组68眼经FFA检查、平均25.6个月随访,其中25%的患眼病灶损害有快慢不一的发展.全部111眼视力在平均30.2个月随访中有18%患眼的视力下降2行以下,且与病灶进展相符,FM100-hue 色彩试验的被随访者中,随访2年以后,其总错误分明显的增加(P<0.01).63眼的明视ERG在随访过程中无明显变化。 结论:大部分干性AMD患眼的病灶损害和视力可以在较长时间内维持稳定。FM100—hue的总错误分可能为监测AMD病情进展的较敏感指标. (中华眼底病杂志,1997,13:150-152)  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