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   60418篇
  免费   4388篇
  国内免费   2133篇
耳鼻咽喉   382篇
儿科学   1409篇
妇产科学   740篇
基础医学   8993篇
口腔科学   791篇
临床医学   4604篇
内科学   9418篇
皮肤病学   1160篇
神经病学   4802篇
特种医学   860篇
外国民族医学   11篇
外科学   4442篇
综合类   6396篇
现状与发展   10篇
预防医学   4916篇
眼科学   996篇
药学   10332篇
  8篇
中国医学   3064篇
肿瘤学   3605篇
  2023年   875篇
  2022年   1497篇
  2021年   1913篇
  2020年   1808篇
  2019年   2388篇
  2018年   2342篇
  2017年   1976篇
  2016年   1899篇
  2015年   2098篇
  2014年   3276篇
  2013年   4014篇
  2012年   3399篇
  2011年   4053篇
  2010年   3380篇
  2009年   2793篇
  2008年   2643篇
  2007年   2480篇
  2006年   2101篇
  2005年   1833篇
  2004年   1634篇
  2003年   1510篇
  2002年   1241篇
  2001年   1088篇
  2000年   832篇
  1999年   849篇
  1998年   697篇
  1997年   646篇
  1996年   556篇
  1995年   487篇
  1994年   437篇
  1993年   410篇
  1992年   371篇
  1991年   349篇
  1990年   306篇
  1989年   247篇
  1988年   243篇
  1986年   183篇
  1985年   806篇
  1984年   1036篇
  1983年   821篇
  1982年   941篇
  1981年   888篇
  1980年   662篇
  1979年   619篇
  1978年   444篇
  1977年   356篇
  1976年   408篇
  1975年   311篇
  1974年   193篇
  1973年   196篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
BACKGROUND: A subgroup of children with obsessive-compulsive and tic disorders are proposed to have an infectious trigger. The purpose of this study was to investigate the relationship between group A streptococcal titers and symptom fluctuations in children with a clinical course resembling that described for pediatric autoimmune neuropsychiatric disorders associated with streptococcus. METHODS: Twenty-five children with obsessive-compulsive disorder and/or tic disorder were evaluated for neuropsychiatric severity and group A streptococcal antibody titers (streptolysin O, deoxyribonuclease B, and carbohydrate A) at 6-week intervals for > or = six consecutive evaluations (total visits=277). RESULTS: Children with large symptom fluctuations (n=15) were compared with children without dramatic fluctuations (n=10). Co-movements of obsessive-compulsive/tic severity and group A streptococcal antibodies were assessed. In subjects with large symptom changes, positive correlations were found between streptococcal titers and obsessive-compulsive severity rating changes (p=.0130). These subjects were also more likely to have elevated group A streptococcal titers during the majority of observations (p=.001). Tic symptom exacerbations occurred more often in the fall/winter months than spring/summer months (p=.03). CONCLUSIONS: Patients with marked obsessive-compulsive/tic symptom changes may be characterized by streptococcal titer elevations and exhibit evidence of seasonal tic exacerbations.  相似文献   
32.
目的:设计、表达两个A型肉毒毒素多表位串联体.方法:从文献报道的A型肉毒毒素(botulinum neurotoxin type A,BoNT/A)的表位及生物信息学方法预测得到的B细胞表位中遴选表位,并加入适当的辅助性元件,设计多表位串联体A、B.对其基因进行优化后,经重叠PCR方法合成串联体A、B的全长基因.分别插入原核表达载体pQE-30,再转化E.coli M15[pREP4]感受态细胞中进行诱导表达,以金属螯合亲和层析法纯化重组蛋白,并进行鉴定.结果与结论:成功设计并构建了两个多表位串联体A、B,并在E.coli中以包涵体形式获得高效表达.Ni-NTA法纯化后分别获得纯度大于92.2%、99%的重组串联体A、B蛋白,并经透析复性法复性.Western印迹和间接ELISA显示纯化、复性后的重组蛋白与抗天然BoNT/A马血清有特异性结合反应.  相似文献   
33.
Zusammenfassung Wir berichten fiber die Doppler-sonographischen Ergebnisse bei 33 Patienten mit einer Anastomose zwischen der A. temporalis superficialis and der A. cerebri media. Die Indikation zur Bypass-Operation beinhaltete rezidivierende TIA oder ein kurz zuvor erworbenes leichtes neurologisches Defizit bei angiographischem Nachweis einseitiger oder beidseitiger tiefer Obliterationen der A. carotis interna und hochgradiger Stenosen oder Verschlüsse im distalen Abschnitt der A. carotis interna bzw. im proximalen Abschnitt der A. cerebri media. Die Funktionsfahigkeit der Anastomose wurde überpriift durch die Berechnung der modifizier ten Pourcelot-Indices (relative enddiastolische Strömungsgeschwindigkeit) der A. temporalis superficialis praeauriculär und am Bohrlochrand Bowie durch den EinfluB der intermittierenden Kompression des den Bypass-versorgenden Gefäßes auf den modifizierten Pourcelot-Index der ipsilateralen A. carotis communis. Bei allen Patienten mit funktionsfahigen Anastomosen, definiert durch einen modifizierten Pourcelot-Index von zumindest 0,20 am Bohrlochrand, kam es zu einer Reduktion dieses Parameters um durchschnittlich 0,08 an der A. carotis communis bei kurzfristiger Kompression des den Bypass-versorgenden Astes. Bei den 18 Patienten mit unilateraler Obliteration der A. carotis interna war der Bypass über-wiegend dann funktionsfähig, wenn die summierten modifizierten Pourcelot-Indices der verbliebenen hirnversorgenden Gefäße um zumindest 10% gegenüber einem vergleichbaren Normalkollektiv reduziert waren. Das Vorhandensein bzw. das Fehlen von Ophthalmica-Kollateralen hatte dabei keinen Einfluß auf den Prozentsatz der funktionsfahigen Anastomosen in diesen Untergruppen. Bei den vier Patienten mit bilateraler Obliteration der A. carotis interna war die angelegte Anastomose in jedem Fall funktionsfähig, während die Hälfte der Patienten mit Stenosen and Verschlüssen im distalen Abschnitt der Carotisstrombahn nur eine ungeniigende Bypass-Funktion zeigten. Die zwei Patienten mit einer Mediahauptstammstenose bzw. -obliteration hatten Indices von 0,45 bzw. 0,46 am Bohrlochrand als Hinweis auf die Funktionstüchtigkeit. Wir Bind der Auffassung, daß man mittels Doppler-sonographischer Kriterien die Funktionsfahigkeit einer Temporalis superficialis-Cerebri media-Anastomose überprüfen kann. Der praeoperativ berechnete summierte modifizierte Pourcelot-Index der verbliebenen hirnversorgenden Arterien kann zumindest bei uni- and bilateraler Internaobliteration als zusatzlicher Parameter herangezogen werden, um die Indikation zur Bypass-Operation zu klären.  相似文献   
34.
乔丽华  马亚平 《实用医技》2007,14(36):4982-4982
近年来,随着社会的发展、科学的进步,社会人口流动量增大,城市人口相对集中,以及文化、生活习惯的差异,使得传染性疾病呈现上升趋势。为了有效控制传染疾病的发生、发展,为预防控制工作提供一些科学依据,现在对我院3年来的相关病例进行了总结、分析如下。  相似文献   
35.
Zusammenfassung Die Humerusschaftfraktur ist in 10–18% der Fälle durch primäre Radialisparese kompliziert. Sekundäre Radialisläsionen treten iatrogen bei intramedullären Verfahren in 3%, bei Plattenosteosynthesen in 15,5% auf. In der überwiegenden Mehrzahl der Fälle (80%) ist der Radialisschaden rückläufig. Eine Verletzung der A. radialis ist eher selten; sie erfordert ein offenes Vorgehen mit lokaler Revision des Gefäßes und Frakturversorgung mittels Plattenosteosynthese. Die Marknagelosteosynthese ist bei einfachen, komplexen oder pathologischen Schaftfrakturen primär oder als Verfahrenswechsel nach primärer Fixateuranlage indiziert. Während auch ausgewählte Frakturen im Collum chirurgicum mit einem Nagel versorgt werden können, sind Frakturen im distalen Viertel des Humerus ausgeschlossen. Frakturen bei kleinen Kopffragmenten weisen ein erhöhtes Komplikationsrisiko auf. Zur Vermeidung von Läsionen der Rotatorenmanschette stehen wir der anterograden Nagelung noch zurückhaltend gegenüber. Bei differenzierter Indikationsstellung und Nachbehandlung erwies sich die retrograde Marknagelung als ein schonendes Verfahren mit hohem Patientenkomfort und gutem funktionellem Ergebnis.  相似文献   
36.
Serum IgA and IgG functional antibodies and their subclasses to Streptococcus pneumoniae capsular antigen found in two aged‐matched cohorts of children with and without otitis media with effusion The relationship between acute otitis media and otitis media with effusion (OME) is uncertain and the aetiology of OME is multifactorial. Otitis media with effusion may be an inflammatory condition; both bacteria and viral infections could play a part in this inflammation. The four bacteria Streptococcus pneumoniae, Haemophilus influenza, Staphylococcus aureus and Branhamella catarrhalis cause 60% of the infections whereas S. pneumoniae accounts for up to 35%. IgA provides the dominant surface response to polysaccharide and lipopolysaccharide antigens, of which IgA2 is the main subclass. Once the mucosa has been breached, most protection is provided by IgG. IgG2 acts mainly against bacterial capsular antigens. This study looked at two groups of 50 children with and without OME who were aged between 3 and 10 years. The aims were to determine if, firstly, the levels of the serum immunoglobulins were different in the two groups, secondly whether these children made the appropriate antibody response to the capsular antigen to S. pneumoniae (PCP), and finally if there was a delay in the maturity of the IgA response. The total IgG, IgA and all subclass levels were measured using radial immunodiffusion. Levels of functional IgA and IgG were measured using ELISAs (25 patients in each group). The results were analysed with non‐parametric tests. The immunoglobulin levels were within the normal levels for both groups. There were very good correlations between the IgG total anti‐PCP and the IgG2 anti‐PCP (R > 0.9, p = 0.001). There was a good correlation between the levels of both IgG total and IgG2 anti‐PCP against IgA total anti‐PCP in both groups (R > 0.85, p > 0.01). This confirms a normal antibody response between both groups of patients. The ages of the controls and patients (50 samples) were correlated with increasing titres of circulating functional antibodies (P = 0.001). This is highly suggestive of a normal age‐related response. In conclusion, the findings were contradictory to our original hypothesis that there is a subtle difference in surface protection between children with and without OME. We believe that a previous history of recurrent acute otitis media is unrelated to the development of OME after 3 years of age.  相似文献   
37.
A 13-year-old boy who had hemophilia A was reported with pain in the left thigh and hip on walking. He had no history of trauma. Severe hemophilia A is diagnosed with a Factor VIII level of <1 iu/dl. The presumptive diagnosis was that of a spontaneous bleed into the hip joint. Factor VIII mutational analysis revealed a C to G substitution at nucleotide 6683 which results in a cystine change at codon 2194. However, the symptoms persisted and an X-ray demonstrated the presence of an acute on chronic slip of the upper femoral epiphysis. The patient was transferred to the center treating his hemophilia where the hip was pinned in situ under cover with Factor VIII. This case demonstrates the need to be aware of a possible traumatic diagnosis of hip pain in a hemophiliac child with a longstanding history of spontaneous bleeding into joints.  相似文献   
38.
A nationwide laboratory-based surveillance system for invasive group A streptococcal (GAS) infections was conducted in The Netherlands from March 1992 until December 2003. Until 1996, all isolates submitted were evaluated clinically and demographically. During this period there was a transition from passive to active surveillance for some of the participating laboratories, corresponding to a national coverage of 50%. During active surveillance, participating laboratories submitted twice as many isolates from invasive GAS disease, whereas the relative submission of isolates representing very severe manifestations (toxic shock-like syndrome, fatality) did not increase. From 1997 onwards, invasiveness was defined solely on the basis of source of isolation (without clinical evaluation). During the period of microbiological and clinical evaluation, microbiological evaluation alone was found to be specific (> 99%), but had limited sensitivity (66%). Estimation of the true rate of invasive GAS disease should be based on an active surveillance system with inclusion of both microbiological and clinical data.  相似文献   
39.
Synkinesias secondary to nerve lesions and aberrant re-innervation are well-known phenomena especially after lesions of the facial nerve. Synkinesias can successfully be treated with botulinum toxin A (BTx A). Synkinesias of the cremaster muscle have not been described or treated to date. We present the case of a 62-year-old man who developed synkinesias of both cremaster muscles after extensive laparatomy for esophageal cancer. Treatment of synkinesias with various oral medications had been unsuccessful. Electromyography-guided injections of BTx A in both cremaster muscles (15 MU on the right and 10 on the left) led to significant symptom relief for an average of 8 weeks. We present the case including pre- and posttreatment video clips.  相似文献   
40.
Clinical efficacy, safety and pharmacokinetic properties of the high-purity double-virus inactivated plasma-derived factor VIII concentrate Haemoctin SDH (pdFVIII) were evaluated in three prospective open-label uncontrolled studies in previously treated patients (PTPs) with severe haemophilia A. The pharmacokinetic properties assessed at baseline and after 3 months of treatment are in accurate accordance with published data and remain unchanged over time (study A, n = 12). Mean terminal elimination half-life was 11.8 and 11.9 h, mean incremental recovery (IU dL(-1)/IU kg(-1)) was 2.3 and 2.0, respectively. Long-term efficacy and safety, in particular the potential immunogenicity, were investigated in a total of 53 PTPs (studies A and B) treated prophylactically and on-demand, as required. PdFVIII has shown to be effective in preventing and controlling bleeding episodes; 23.5% of patients were free of bleeding events. A total of 177 haemorrhages occurred with 74.0% resolving after a single infusion, 87.6% within two infusions. 98.3% of responses reported on haemorrhages were rated as 'excellent' or 'good'. Moreover, 'excellent' haemostatic efficacy has been demonstrated in 10 surgical procedures including general and severe orthopaedic interventions (study C). No complication occurred in any surgery. Few adverse events were reported, one patient developed a high-titre FVIII inhibitor without clinical relevance. In all three studies, over 6 million units were administered in nearly 4300 infusions, approximately 94% units or infusions were given for prophylaxis and only 6% for treatment on-demand. In conclusion, pdFVIII has shown to be effective, safe and well tolerated in long-term prophylaxis and treatment on-demand as well as after minor and major surgical procedures.  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