全文获取类型
收费全文 | 6894篇 |
免费 | 440篇 |
国内免费 | 91篇 |
专业分类
耳鼻咽喉 | 74篇 |
儿科学 | 296篇 |
妇产科学 | 212篇 |
基础医学 | 1340篇 |
口腔科学 | 53篇 |
临床医学 | 711篇 |
内科学 | 1266篇 |
皮肤病学 | 186篇 |
神经病学 | 491篇 |
特种医学 | 461篇 |
外科学 | 844篇 |
综合类 | 58篇 |
预防医学 | 317篇 |
眼科学 | 175篇 |
药学 | 405篇 |
中国医学 | 5篇 |
肿瘤学 | 531篇 |
出版年
2022年 | 43篇 |
2021年 | 62篇 |
2020年 | 49篇 |
2019年 | 71篇 |
2018年 | 101篇 |
2017年 | 73篇 |
2016年 | 88篇 |
2015年 | 118篇 |
2014年 | 131篇 |
2013年 | 194篇 |
2012年 | 290篇 |
2011年 | 262篇 |
2010年 | 183篇 |
2009年 | 191篇 |
2008年 | 262篇 |
2007年 | 334篇 |
2006年 | 261篇 |
2005年 | 284篇 |
2004年 | 255篇 |
2003年 | 259篇 |
2002年 | 246篇 |
2001年 | 261篇 |
2000年 | 237篇 |
1999年 | 203篇 |
1998年 | 151篇 |
1997年 | 140篇 |
1996年 | 122篇 |
1995年 | 112篇 |
1994年 | 83篇 |
1993年 | 85篇 |
1992年 | 113篇 |
1991年 | 133篇 |
1990年 | 109篇 |
1989年 | 162篇 |
1988年 | 136篇 |
1987年 | 111篇 |
1986年 | 113篇 |
1985年 | 131篇 |
1984年 | 74篇 |
1983年 | 60篇 |
1982年 | 49篇 |
1981年 | 42篇 |
1980年 | 52篇 |
1979年 | 45篇 |
1976年 | 42篇 |
1975年 | 53篇 |
1936年 | 47篇 |
1935年 | 45篇 |
1933年 | 51篇 |
1932年 | 49篇 |
排序方式: 共有7425条查询结果,搜索用时 0 毫秒
21.
Nuthapong Ukarapol Nirush Lertprasertsuk George J. Fuchs Lumduan Wongsawasdi Virat Sirisanthana 《Digestive endoscopy》2004,16(1):26-29
Objective: To evaluate the role of gastrointestinal (GI) endoscopy in human immunodeficiency virus (HIV)‐infected children with GI problems. Methods: From 1998 to 2002, we retrospectively reviewed all cases of HIV‐infected children presenting with GI problems in which an upper or lower GI endoscopy was indicated. The initial diagnostic endoscopic examination and any repeat endoscopic session leading to a new diagnosis were used in the data analysis. Tissue biopsies were obtained from all abnormal lesions and representative sites of normal‐appearancing GI mucosa. Results: Fourteen patients (median age: 22.5 months) underwent 23 sessions of GI endoscopy, including 10 esophagogastroduodenoscopy, nine colonoscopy and four flexible sigmoidoscopy. Chronic diarrhea was the most common indication, followed by lower GI bleeding, abdominal/retrosternal pain, dysphagia/odynophagia, and upper GI bleeding. Gross endoscopic abnormalities were observed in 78.3%; whereas histological inflammation and opportunistic pathogens were identified in 87% and 43.5%, respectively. Cytomegalovirus was the most common identified pathogen. Abnormal gross findings were significantly associated with histological inflammation and identification of pathogens (P = 0.006 and 0.046, respectively). Specific changes in medical management were made in 50% of cases as a result of endoscopic investigation. Conclusion: If non‐invasive investigations for HIV‐infected children with GI symptoms fail to establish a diagnosis, gastrointestinal endoscopy should be performed and often yields a positive result leading to changes in medical management. 相似文献
22.
Uwe Fuchs Armin Zittermann Ole Suhr Gösta Holmgren Gero Tenderich Kazutomo Minami Reiner Koerfer 《American journal of transplantation》2005,5(5):1159-1162
Senile systemic amyloidosis (SSA) results from deposition, predominantly in the heart, of amyloid fibrils derived from wild-type transthyretin (T TR) molecules. Cardiac autopsies indicate that SSA progressively increases in subjects 80 years of age and older. However, only a few cases of patients with SSA and cardiac failure have been recognized by cardiac biopsies during life. Here, we report a case of heart transplantation in a 68-year-old male patient with SSA. After cardiopulmonary resuscitation in October 1998, he underwent complete evaluation. Myocardial biopsies revealed the presence of amyloid deposition. Immunohistochemical staining of the amyloid indicated T TR. Genomic DNA analysis of the T TR exons did not result in any identification of a mutation. In 2001, heart transplantation was performed because progressive heart failure occurred. At the 1-year follow-up, no amyloid deposits were found in the donor heart. At the 2-year follow-up, the patient's physical and mental health was excellent. We conclude that heart transplantation can be an effective treatment in progressive heart failure due to SSA. 相似文献
23.
D Mahalanabis H Ashraf MM Rahman GJ Fuchs 《Acta paediatrica (Oslo, Norway : 1992)》1998,87(11):1113-1115
One-hundred and six male children aged 6-23 months with a history of acute watery diarrhoea of less than 72 h duration were randomized to receive either folic acid in a dose of 5 mg at 8-h intervals or placebo for 5 d. There were 54 children in the folic acid group and 52 in the placebo group. The admission characteristics were comparable between the two groups. No significant differences were observed in the intake of oral rehydration solution or stool output between the groups. The mean ± SD of total stool output (g kg−1 ) was 532 ± 476 vs 479 ± 354 and the duration (h) of diarrhoea was 108 ± 68 vs 103 ± 53 in the folic acid vs placebo group, respectively. The findings, therefore, should have a positive influence on preventing the inappropriate use of folic acid in acute diarrhoea. 相似文献
24.
25.
Dr. S. Fuchs Ch. Jürgens A. P. Schulz M. E. Wenzl D. Wolter 《Trauma und Berufskrankheit》2005,7(2):83-88
Zusammenfassung Winkelstabile Plattenfixateur-interne-Systeme haben in den letzten 20 Jahren zunehmend an Bedeutung gewonnen. Die aus der Winkelstabilität resultierende flächenhafte Krafteinleitung und gleichmäßigere Kraftverteilung führen zu einer besseren Knochenbruchheilung insbesondere im metaphysischen Bereich und bei Osteoporose. Bei Marknagelsystemen ist die Winkelstabilität bislang nur partiell verwirklicht. Der vorgestellte winkelstabile Tibiamarknagel realisiert an jedem einzelnen Bolzen eine Winkelstabilität mit dem einliegenden intramedullären Kraftträger. Von Februar 2002–August 2004 wurden 21 Patienten mit ihm behandelt. In 13 Fällen wurden Frakturen stabilisiert, 6 Patienten hatten Fehlstellungen, 2 Patienten Pseudarthrosen. Zum Nachuntersuchungszeitpunkt waren alle Behandlungen abgeschlossen. Postoperative Komplikationen traten nicht auf. In allen Fällen wurde eine vollständige Durchbauung erreicht. In 6 Fällen fand sich radiologisch eine verzögerte Knochenbruchheilung. Die ersten klinischen Erfahrungen mit dem winkelstabilen Tibiamarknagel zeigen, dass dieser aufgrund der höheren Primärstabilität insbesondere im metaphysären Knochenbereich mit kurzen Fragmenten sowie bei Osteoporose Vorteile gegenüber anderen nichtwinkelstabilen oder nur partiell winkelstabilen Marknagelsystemen erbringt. Die verzögerten Knochenbruchheilungen bedürfen weiterer klinischer und biomechanischer Untersuchungen. 相似文献
26.
J L Fuchs 《Neurobiology of aging》1991,12(5):523-530
The enzyme 5'-nucleotidase is present in glial and neuronal membranes, and catalyzes the formation of adenosine, which in turn can act as a neuromodulator or neurotransmitter. The present study found marked increases in histochemically demonstrated 5'-nucleotidase activity in most regions of rat brain from young adulthood (3-4 months) to middle age (12-18 months), with smaller or no changes between middle and old age (24-32 months). The aging adult cerebellum showed alterations in the histochemical pattern, with declines in the molecular layer and increases in the Purkinje layer. Both myelin and synaptic plasma membrane fractions from forebrain showed increases in enzyme activity. Assays of various other body tissues suggested that the increases are fairly specific to brain, and thus apparently do not represent a ubiquitous cellular mechanism of aging. Changes in brain 5'-nucleotidase activity during aging probably reflect the increasing number and size of glial cells, and perhaps also affect synaptic transmission through regulation of adenosine. 相似文献
27.
Intestinal obstruction proximal to a transition zone without an interposed physical barrier usually indicates Hirschsprung disease. The authors report one case of focal small bowel muscular thinning just distal to a transition zone that produced clinical and radiographic findings that simulated long-segment Hirschsprung disease in a 2-day-old infant. 相似文献
28.
The suprachiasmatic nucleus (SCN) of rat and hamster have been studied extensively and shown to play critical roles in circadian rhythmicity. [125I]Vasoactive intestinal peptide (VIP) binding levels are high in the rat SCN, suggesting that VIP receptors may be an important component of SCN function. In contrast to previously demonstrated diurnal variations in VIP immunoreactivity and VIP mRNA, the present study found [125I]VIP binding to be stable across the light-dark cycle in both rat and hamster SCN. High [125I]VIP labeling appeared to be coextensive with the rat SCN but extended somewhat beyond the cytoarchitectonic boundaries of the hamster SCN. Binding density in hamster SCN was slightly higher than in rat. In the developing rat SCN, [125I]VIP binding levels distinguished the SCN on embryonic day 18, and appeared to increase to postnatal day 10 before declining to adult levels. The early presence of [125I]VIP binding suggests possible involvement of VIP receptors in fetal entrainment of circadian rhythms. 相似文献
29.
30.
M. A. Pfaller A. L. Barry L. D. Sabath B. N. Kreiswirth P. R. Murray P. C. Fuchs J. C. McLaughlin 《European journal of epidemiology》1993,9(6):658-662
The in vitro activity of ceftriaxone and six additional antimicrobial agents (ceftizoxime, cefoperazone, cefuroxime, fleroxacin, ciprofloxacin, and trimethoprim/sulfamethoxazole) was assessed or 602 recent clinical isolates of staphylococci from six geographically distinct medical centers in North America. All seven antimicrobial agents were active (90–100% of strains susceptible) against oxacillin-susceptible (OS) strains of Staphylococcus aureus (OSSA) and coagulase-negative staphylococci (OSCNS) but had limited activity against oxacillin resistant (OR) staphylococci. Our assessment of the in vitro antistaphylococcal activity of ceftriaxone against contemporary isolates of Staphylococcus aureus and coagulase-negative staphylococci indicates that the activity versus OS staphylococci has not changed over the past decade despite widespread use of the drug. It appears that these agents will continue to be useful for empiric therapy in those centers in which OR strains are uncommon.Corresponding author. 相似文献