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   18270篇
  免费   1849篇
  国内免费   399篇
耳鼻咽喉   59篇
儿科学   1748篇
妇产科学   278篇
基础医学   1879篇
口腔科学   158篇
临床医学   1165篇
内科学   2797篇
皮肤病学   172篇
神经病学   856篇
特种医学   177篇
外科学   981篇
综合类   3046篇
现状与发展   2篇
预防医学   1677篇
眼科学   267篇
药学   785篇
  10篇
中国医学   4267篇
肿瘤学   194篇
  2024年   42篇
  2023年   339篇
  2022年   589篇
  2021年   1010篇
  2020年   980篇
  2019年   696篇
  2018年   642篇
  2017年   837篇
  2016年   812篇
  2015年   690篇
  2014年   1272篇
  2013年   1169篇
  2012年   1010篇
  2011年   1083篇
  2010年   792篇
  2009年   723篇
  2008年   648篇
  2007年   686篇
  2006年   652篇
  2005年   533篇
  2004年   494篇
  2003年   439篇
  2002年   354篇
  2001年   339篇
  2000年   303篇
  1999年   267篇
  1998年   238篇
  1997年   194篇
  1996年   166篇
  1995年   218篇
  1994年   180篇
  1993年   179篇
  1992年   162篇
  1991年   174篇
  1990年   151篇
  1989年   145篇
  1988年   143篇
  1987年   119篇
  1986年   118篇
  1985年   152篇
  1984年   116篇
  1983年   74篇
  1982年   109篇
  1981年   92篇
  1980年   69篇
  1979年   79篇
  1978年   45篇
  1977年   43篇
  1976年   49篇
  1975年   28篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
[目的]了解居民户食用盐的碘含量情况,以便采取针对性的防控措施,为持续性消除碘缺乏病工作提供参考依据。[方法]对2004~2010年日照市居民户食用盐监测资料进行分析。[结果]2004~2010年累计检测7 760份居民户食用盐,合格碘盐7 362份,不合格碘266份,非碘盐132份,碘盐覆盖率为98.30%,碘盐合格率为96.51%,合格碘盐食用率为94.87%,非碘盐率为1.70%,盐碘中位数为29.30mg/kg。2004~2010年,碘盐合格率分别为95.11%、96.65%、92.58%、96.70%、97.30%、98.60%、98.20%,合格碘盐食用率分别为94.56%、95.27%、91.34%、92.60%、95.60%、97.60%、96.90%。东港区、岚山区、莒县、五莲县,碘盐合格率分别为95.59%、95.15%、96.95%、98.11%,合格碘盐食用率分别为93.50%、91.65%、96.03%、97.82%。[结论]日照市碘盐质量稳定,居民合格碘盐食用率符合国家消除碘缺乏病的标准。  相似文献   
992.
艾滋病已在全球广泛流行,由于艾滋病患者的临床表现多样,病情进展快,死亡率高,如何降低HIV感染者和艾滋病患者的死亡率已成为当前艾滋病防治的重要任务.HIV感染者和艾滋病患者的死亡与多种因素有关,既涉及宿主本身的因素,又涉及病毒方面的因素,还有治疗及其他社会心理因素等.此文主要对国内外在HIV感染者和艾滋病患者死亡危险因素的相关研究作一综述.  相似文献   
993.
Magnesium is a micronutrient essential for the normal functioning of the cardiovascular system, and Mg deficiency (MgD) is frequently associated in the clinical setting with chronic pathologies such as CHF, diabetes, hypertension, and other pathologies. Animal models of MgD have demonstrated a systemic pro-inflammatory/pro-oxidant state, involving multiple tissues/organs including neuronal, hematopoietic, cardiovascular, and gastrointestinal systems; during later stages of MgD, a cardiomyopathy develops which may result from a cascade of inflammatory events. In rodent models of dietary MgD, a significant rise in circulating levels of proinflammatory neuropeptides such as substance P (SP) and calcitonin gene-related peptide among others, was observed within days (1–7) of initiating the Mg-restricted diet, and implicated a neurogenic trigger for the subsequent inflammatory events; this early “neurogenic inflammation” phase may be mediated in part, by the Mg-gated N-methyl-D-aspartate (NMDA) receptor/channel complex. Deregulation of the NMDA receptor may trigger the abrupt release of neuronal SP from the sensory-motor C-fibers to promote the subsequent pro-inflammatory changes: elevations in circulating inflammatory cells, inflammatory cytokines, histamine, and PGE2 levels, as well as formation of nitric oxide, reactive oxygen species, lipid peroxidation products, and depletion of key endogenous antioxidants. Concurrent elevations of tissue CD14, a high affinity receptor for lipopolyssacharide, suggest that intestinal permeability may be compromised leading to endotoxemia. If exposure to these early (1–3 weeks MgD) inflammatory/pro-oxidant events becomes prolonged, this might lead to impaired cardiac function, and when co-existing with other pathologies, may enhance the risk of developing chronic heart failure.  相似文献   
994.
Summary A 12-year-old girl with a 2-month history of fever and abdominal pain was admitted to our hospital. Ultrasound and CT scans of the abdomen showed multiple hypoechoic lesions of liver and spleen. Screening for zoonosis revealed high positive titers to Bartonella henselae. T-cell deficiency was demonstrated and remained almost unchanged during a follow-up of 11 months. A review of the literature shows that disseminated visceral affection is a rare presentation of cat scratch disease (CSD) in childhood and adolescence. Further immunological investigations are needed in more patients with CSD to confirm whether an altered imunological state may be responsible for the atypical visceral manifestation of CSD. Received: May 18, 1999 · Revision accepted: January 19, 2000  相似文献   
995.
Use of recombinant factor VIIa (rFVIIa, NovoSeven in patients with congenital FVII deficiency has been reported for the prophylactic management of surgical bleeding and for the treatment of acute bleeding episodes. Because of its short half-life, the use of rFVIIa on a regular prophylactic regimen has not been routinely adopted. In this report, we describe our successful experience with rFVIIa prophylaxis in preventing recurrent target joint bleeding in a severely FVII-deficient adolescent.  相似文献   
996.
Abstract A patient presented with hematological evidence of vitamin B12 deficiency. The Schilling test performed suggested intestinal malabsorption and further investigation revealed heavy infestation with Giardia lamblia. Specific treatment of the giardiasis with tinidazole resulted in correction of the abnormalities in vitamin B12 absorption. These findings, together with the absence of other causes of vitamin B12 deficiency, suggest that giardiasis should be considered as a cause of vitamin B12 deficiency.  相似文献   
997.
We studied a family in which the proband, a 13-year-old boy, had unmeasurable plasma levels of coagulation factor V antigen and activity. Clinical symptoms were severe, with several episodes of haemorrhages in the mucosal tracts (gastrointestinal, nose and urinary) and recurrent haemarthroses that caused permanent arthropathy. Sequence analysis of the factor V gene demonstrated the presence of a novel 2 base pair (bp) homozygous deletion in exon 13 at positions 2833-2834. This mutation, present in the heterozygous state in the asymptomatic mother and absent in the healthy brother, introduced a frameshift and a premature stop at codon 900. This would predict the synthesis of a truncated factor V molecule, lacking part of the B domain and the complete light chain. Because of the existence of a surveillance mechanism that selectively recognizes and degrades mRNA molecules carrying premature termination codons, we analysed the relative abundance of mutant vs. wild-type mRNA molecules in the platelets of the heterozygous proband's mother. The mutant mRNA was significantly reduced in amount (mutant/wild-type ratio 0.35). This is the first reported mutation in the factor V gene causing severe factor V deficiency, the effect of which was quantitatively analysed at mRNA level.  相似文献   
998.
Glucose-6-phosphate dehydrogenase A- (G6PD A-) deficiency is a common enzymopathy in Africa that sporadically leads to manifest haemolytic anaemia. It is not exactly known how far the haematological status of individuals with either homozygous or heterozygous G6PD A- deficiency differs from that of individuals with normal G6PD activity. In a field study in Nigeria, we determined G6PD gene variants, the corresponding G6PD and pyruvate kinase (PK) activities, and basic haematological parameters in clinically healthy individuals, who were, in part, asymptomatically infected by malaria parasites. Red blood cell counts and haemoglobin levels were lower in G6PD A- deficient than in G6PD normal subjects. PK activities were higher in G6PD deficients, indicating a younger red cell population in these individuals. These findings suggest that G6PD A- deficiency is accompanied by chronic subclinical haemolysis. As a consequence, the reduced life span of red cells leads to an impaired diagnosis of G6PD heterozygosity when applying routine biochemical methods.  相似文献   
999.
We undertook a prospective study to test Simoons' hypothesis that in certain susceptible races milk exerts a cataractogenic effect. Overall milk intake in low lactase deficiency areas did not correlate with cataract occurrence. Subgrouping of cataract patients revealed that greater milk intake did show positive correlation with cortical cataracts. Cortical cataracts were also markedly more common in females. Analysis of data from three different regions showed greater milk intake in cortical cataract patients only. Our data indicate the importance of specifying cataract type in cataract studies and highlight the problem this approach brings forth. We noted no different trends in subjects from northwest and southeast India, although the number of subjects from the southeast was considerably less. Patients with early cortical cataracts may be advised to restrict milk intake.Part of this material was presented at second cataract epidemiology meeting at Bonn in March 1988. A brief report has been accepted for publication in the proceedings of the meeting to be published inDevelopment of Ophthalmology, Vol. 17, 1988.  相似文献   
1000.
Factor X (FX) deficiency is a rare autosomal recessive disorder. The phenotype and genotype of 15 Iranian patients with FX deficiency from 13 unrelated families with a high frequency of consanguinity were analysed. Five different assays identified four patients from three families with a discrepancy between low-FX coagulant activity (FX:C) and higher-FX antigen (FX:Ag) (a type II deficiency). The remaining 11 patients had parallel reductions of FX:C and FX:Ag (a type I deficiency). Nine different homozygous candidate mutations were identified, of which eight were novel. The four type II cases were associated with an Arg(-1)Thr missense mutation in the prepropeptide: Arg(-1) is highly conserved in all vitamin K-dependent proteins. Four type I mutations (Gly78Asp, Cys81Tyr, Gly94Arg and Asp95Glu) were localized to the EGF-1 and EGF-2 domains, for which molecular views showed that the protein folding would be disrupted. The type I mutation Gly222Asp was localized in the catalytic domain of FX, and is sufficiently close to the Asp-His-Ser catalytic triad to disrupt its correct protein folding. The two type I splice site mutations were IVS1+3, A-->T and IVS2-3, T-->G. These novel homozygous FX mutations were consistent with their phenotypes and agree with experimental data from knockout mice, indicating that FX is an essential protein for survival.  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