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   69092篇
  免费   6348篇
  国内免费   3627篇
耳鼻咽喉   493篇
儿科学   1049篇
妇产科学   1069篇
基础医学   9448篇
口腔科学   1607篇
临床医学   7422篇
内科学   11983篇
皮肤病学   932篇
神经病学   4924篇
特种医学   2433篇
外国民族医学   25篇
外科学   8314篇
综合类   8140篇
现状与发展   12篇
一般理论   10篇
预防医学   4112篇
眼科学   1639篇
药学   6826篇
  15篇
中国医学   2280篇
肿瘤学   6334篇
  2024年   109篇
  2023年   666篇
  2022年   1536篇
  2021年   2087篇
  2020年   1618篇
  2019年   1584篇
  2018年   1925篇
  2017年   1707篇
  2016年   1648篇
  2015年   2354篇
  2014年   2834篇
  2013年   2805篇
  2012年   4225篇
  2011年   4363篇
  2010年   2688篇
  2009年   2193篇
  2008年   3263篇
  2007年   3389篇
  2006年   3099篇
  2005年   3005篇
  2004年   2264篇
  2003年   2127篇
  2002年   1776篇
  2001年   3132篇
  2000年   3168篇
  1999年   2851篇
  1998年   1300篇
  1997年   1127篇
  1996年   820篇
  1995年   752篇
  1994年   674篇
  1993年   518篇
  1992年   1296篇
  1991年   1203篇
  1990年   1072篇
  1989年   1115篇
  1988年   998篇
  1987年   936篇
  1986年   860篇
  1985年   735篇
  1984年   473篇
  1983年   390篇
  1982年   210篇
  1981年   177篇
  1980年   140篇
  1979年   232篇
  1978年   108篇
  1977年   100篇
  1973年   103篇
  1971年   100篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
[目的]探讨各型肝炎的感染率。[方法]研究对象为我院住院及门诊患者,共计4110例。采用微粒子酶免分析法(MEIA)及酶联免疫吸附法(ELISA)进行肝炎分型(甲、乙、丙、丁、戊、庚肝)检测。[结果]4110例受检者中,单纯乙肝感染者133例,占3.24%;单纯丙肝感染者134例,占3.26%;单纯戊肝感染者2例,占0.05%;乙肝合并丙肝感染者3例,占0.07%;丙肝合并戊肝感染者1例,占0.02%;HAV、HDV、HGV无一例感染,感染率为0。另外,男性受检者2088人,乙肝感染者88人,占4.21%;丙肝感染者48人,占2.30%;女性受检者2022人,乙肝感染45人,占2.23%;丙肝感染86人,占4.25%。[结论]除丙肝外,各型感染率均低于全国平均感染率,与相关资料报道相差甚远。乙肝及丙肝仍以单纯感染多见。另,本组资料还显示,男性较女性更易感染乙肝病毒,而女性感染丙肝者远远高于男性,对于丙肝感染的性别差异,尚无报道,需进一步探讨。  相似文献   
53.
54.
OBJECTIVE: Surgical reduction and retention of apophyseal avulsion injuries at the medial epicondyle to prevent joint instability, lasting malalignment, or pseudarthrosis. INDICATIONS: Absolute: intraarticular apophyseal dislocation of the medial epicondyle, complete lesion of the ulnar nerve. Relative: dislocation of the apophysis (> 4 mm) in children > 5 years of age; the need for intervention increases in children as the degree of dislocation, age, and athletic activity increase. CONTRAINDICATIONS: Dislocation of the medial epicondyle (< or = 4 mm) in children < 5 years of age, provided the fragment location is not intraarticular. SURGICAL TECHNIQUE: Open reduction of the apophysis through a medial approach. Identification of the ulnar nerve. In young children or with small fragments fixation with Kirschner wire. Screw fixation in older children or for larger fragments. POSTOPERATIVE MANAGEMENT: Long upper-arm plaster cast until wound healing is achieved. Subsequently, upper-arm plaster cast for 3 weeks. Removal of Kirschner wires after 4-6 weeks, screw removal after 8-12 weeks. Physiotherapy only if marked reduction of elbow mobility is found 6 weeks after cast removal. RESULTS: From January 1, 1994 to December 31, 2003, 25 children with an average age of 12 years suffering from medial epicondylar avulsion fractures were operated on using open reduction and Kirschner wire fixation. An average of 3 years after the injury 14 of these children underwent follow-up examination using a procedure that took subjective, clinical and radiologic parameters into account. Two children showed a slight reduction in overall strength of the injured extremity when compared with the contralateral extremity. One child had a flexion deficit of 10 degrees, all other children showed movement limitations of < or = 5 degrees compared to the contralateral extremity. In all the cases available to follow-up, there was a slight increase in valgus alignment of the elbow joint compared with the uninjured side (3 degrees on average). All fractures consolidated within 6 weeks.  相似文献   
55.
PINK1 mutations in sporadic early-onset Parkinson's disease.   总被引:5,自引:0,他引:5  
Pathogenic PINK1 mutations have been described in PARK6-linked Parkinson's disease (PD) patients of Asian origin. However, data on the frequency of PINK1 mutations in sporadic early-onset Parkinson's disease (EOPD) Asian patients are lacking. The objectives of this study were to report the frequency of PINK1 mutations of sporadic EOPD in an Asian cohort comprising of ethnic Chinese, Malays, and Indians, and to highlight a PINK1-positive patient who presented with restless legs symptoms. Eighty consecutive sporadic EOPD patients from the movement disorder clinics of two major tertiary institutions in the country were included. We performed sequence analysis of all the coding and exon-intron junctions of the PINK1 using specific primer sets. In addition, we genotyped polymorphisms detected from the analysis in a group of sporadic PD patients and controls. Three different mutations (two homozygous nonsense and one heterozygous missense) in the putative kinase domain were found in three patients, giving a 3.7% frequency of PINK1 mutations in our EOPD cohort. All the mutations were absent in 200 healthy controls. One patient with a novel homozygous nonsense PINK1 mutation presented unusually with restless legs symptoms. Separately, analysis of the frequency of four PINK1 polymorphisms in a group of sporadic PD and controls did not reveal any significant differences. We highlight a 3.7% frequency of PINK1 mutations in an Asian cohort (ethnic Chinese, Malay, and Indian) of EOPD. The phenotypic spectrum associated with PINK1-positive patients may be wider than previously reported. Polymorphisms of PINK1 do not appear to modulate risk of PD in our population.  相似文献   
56.
目的 探讨中西医结合治疗慢性结肠炎的体会。方法 对采用中草药灌肠液E+西医药治疗66例慢性结肠炎的临床观察进行分析。结果66例患者中,有效率达96%左右。结论 慢性结肠炎是我国的常见病及多发病,采用中草药+西医药治疗,效果好,药价低廉,操作简便,值得推广,应予重视。  相似文献   
57.
氧化砷对小鼠腹水型肝癌细胞的作用   总被引:2,自引:0,他引:2  
目的 :研究氧化砷对移植性腹水型肝癌细胞的抗癌作用。方法 :肝癌细胞 (1 8× 10 7)接种入小鼠腹腔。对照组注射NS(0 8mL) ,余组用氧化砷 (1,2 ,3μmol/L)腹腔注射 ,每日 1次 ,共 10日。结果 :第 10天腹水细胞计数 ,1,2和 3μmol/L组瘤细胞锐减 (P <0 0 5 ) ,但第 16天腹水肿瘤细胞急骤增加。结论 :氧化砷对腹水肿瘤细胞有暂时抑制作用。  相似文献   
58.
庆大霉素对豚鼠前庭上皮IGF-1及其受体表达的影响   总被引:1,自引:0,他引:1  
目的:研究庆大霉素对豚鼠前庭上皮胰岛素样生长因子-1(insulin-like growth factor-1,IGF-1)及其受体(insulin-like growth factor-1 receptor,EGF-1R)表达的影响,并探讨其生物学特性。方法:采用免疫组织细胞化学方法,以抗IGF-1及IGF-1R抗体为标记物,检测庆大霉素损伤后豚鼠前庭上皮自发修复期IGF-1及IGF-1R的表达变化和分布特点;采用Brdu体内标记和抗Brdu抗体免疫组化染色,检测庆大霉素损伤后豚鼠前庭上皮增殖的变化。结果:IGF-1及IGF-1R在正常成年豚鼠前庭上皮细胞中有低水平表达,庆大霉素损伤后,其表达增多。在1d组IGF-1及IGF-1R表达最强,其后逐渐减少。在正常对照组中无Brdu阳性细胞。各实验组均观察到Brdu阳性细胞,7d组最多。结论:庆大霉素损伤后,豚鼠前庭上皮IGF-1及IGF-1R表达增强,其时程变化与细胞增殖活动密切相关。IGF-1在豚鼠前庭上皮损伤后的细胞增殖中可能起重要信号转导作用。  相似文献   
59.
This study examined the immunoregulatory role of recombinant interleukin 4 (IL-4), also known as B-cell stimulating factor 1, on the generation of cytotoxic effector cells from normal and leukaemic human blood mononuclear cells. When tested on cells from normal individuals, the addition of IL-4 to mixed lymphocyte cultures led to a dose-dependent proliferation of T-helper cells (CD3, 4 positive) with a concomitant decrease in phenotypic and functional cytotoxic T cells and natural killer (NK) cells. IL-4 also inhibited the interleukin-2 (IL-2)-induced generation of lymphokine-activated killer (LAK) activity when added at the beginning of mixed lymphocyte culture. When tested on mature leukaemic NK cells, IL-4 also inhibited the ability of IL-2 to induce LAK function using a short-term culture system. These results show that IL-4 acts on both normal and leukaemic cells and suggests that it acts at more than one level during the development of LAK function.  相似文献   
60.
The thiadiazinone derivative [+]-EMD 60263 ((+)-5-(1-(α-ethylimino-3,4-dimethoxybenzyl)-1,2,3,4- tetrahydroquinoline-6-yl)-6-methyl-3,6-dihydro-2H-1,3,4 -thiadiazine-2-on) is a Ca2+-sensitizing agent with only minor phosphodiesterase inhibitory activity. Our aim was to characterize the inotropic and electrophysiological effects of [+]-EMD 60263 and its enantiomer [-]-EMD 60264 in several cardiac muscle preparations. The Ca2+-sensitizing activity resided in the [+]-enantiomer only. [+]-EMD 60263 (3 μM) shifted the EC50 of Ca2+ for contractile activation of skinned fibers of pig heart from 2.41 μM to 0.73 μM, whereas [-]-EMD 60264 (30 μM) was ineffective. In Langendorff-perfused guinea pig hearts, [+]-EMD 60263 and [-]-EMD 60264 induced concentration-dependent positive and negative inotropic effects, respectively; both enantiomers reduced spontaneous heart rate but did not influence perfusion pressure. The maximum increase in force of human atrial trabeculae was 35 % of pre-drug control with [+]-EMD 60263 in comparison to 113 % with forskolin. In guinea-pig papillary muscles, [+]-EMD 60263 and [-]-EMD 60264 had opposite inotropic responses, however, both agents similarly prolonged action potential duration. Both enantiomers concentration-dependently blocked the rapidly activating component IKr of the delayed rectifier in guinea-pig myocytes. The block saturated at potentials positive to +30 mV, closely resembling the effects of the antiarrhythmic agent E-4031 which had been originally used to define IKr. It is concluded, that the positive inotropic action of [+]-EMD 60263 can be explained by prevalence of the Ca2+-sensitizing effect. The accompanying prolongation in action potential duration is caused by block of the IKr component of the delayed rectifier. While the inotropic effects are stereoselective, most of the electrophysiological actions are clearly independent of sterical configuration. The combination of Ca2+-sensitizing with class-III antiarrhythmic action may provide an interesting pharmacological profile of potential therapeutic use. Received: 7 January 1997 / Accepted: 25 February 1997  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