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   256811篇
  免费   13290篇
  国内免费   256篇
耳鼻咽喉   4076篇
儿科学   9895篇
妇产科学   7201篇
基础医学   37676篇
口腔科学   7366篇
临床医学   19958篇
内科学   47451篇
皮肤病学   7463篇
神经病学   23333篇
特种医学   11184篇
外国民族医学   55篇
外科学   40274篇
综合类   2202篇
一般理论   71篇
预防医学   13774篇
眼科学   6365篇
药学   17933篇
中国医学   516篇
肿瘤学   13564篇
  2021年   1775篇
  2020年   1558篇
  2019年   2055篇
  2018年   3896篇
  2017年   3371篇
  2016年   4389篇
  2015年   4121篇
  2014年   4737篇
  2013年   7884篇
  2012年   10390篇
  2011年   11226篇
  2010年   6522篇
  2009年   4972篇
  2008年   11295篇
  2007年   12005篇
  2006年   11875篇
  2005年   11851篇
  2004年   11259篇
  2003年   11239篇
  2002年   11058篇
  2001年   12046篇
  2000年   13240篇
  1999年   9523篇
  1998年   3036篇
  1997年   2702篇
  1996年   2251篇
  1995年   1965篇
  1994年   1864篇
  1993年   1802篇
  1992年   4643篇
  1991年   4388篇
  1990年   4353篇
  1989年   4145篇
  1988年   3630篇
  1987年   3633篇
  1986年   3400篇
  1985年   3422篇
  1984年   2692篇
  1983年   2196篇
  1982年   1553篇
  1981年   1480篇
  1979年   2408篇
  1978年   1852篇
  1977年   1642篇
  1976年   1368篇
  1975年   1674篇
  1974年   1679篇
  1973年   1612篇
  1972年   1410篇
  1971年   1354篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
991.
Cell culture-based influenza vaccine manufacturing is of growing importance. Depending on virus strains, differences in infection dynamics, virus-induced apoptosis, cell lysis and virus yields are observed. Comparatively little is known concerning details of virus–host cell interaction on a cellular level and virus spreading in a population of cells in bioreactors. In this study, the infection of MDCK cells with different influenza A virus strains in lab-scale microcarrier culture was investigated by flow cytometry. Together with the infection status of cells, virus-induced apoptosis was monitored. A mathematical model has been formulated to describe changes in the concentration of uninfected and infected adherent cells, dynamics of virus particle release (infectious virions, hemagglutinin content), and the time course of the percentage composition of the cell population.  相似文献   
992.
The pharmacokinetics of opioids are impaired in patients with liver and renal failure. Fentanyl, sufentanil, and alfentanil are metabolized in the liver. The extrahepatic metabolism by renal enzymes is gaining more importance in patients with severe liver disease. Pharmacokinetic effects of single doses of fentanyl and sufentanil are not affected in liver and renal failure; however, continuous infusion of fentanyl may result in accumulation and prolonged opioid effects. Plasma clearance and elimination of alfentanil are reduced in patients with liver failure and its clinical use can therefore not be recommended. A reduction in alfentanil dosing is not necessary in patients with renal failure. Remifentanil is the opioid of choice in patients with liver and renal failure. The clearance of morphine is reduced in liver failure. In renal failure an accumulation of morphine metabolites has been demonstrated, and thus, application of morphine is not recommended in patients with liver and renal failure. A reduction in piritramide dosing is necessary in patients with liver failure.  相似文献   
993.
994.
Symptomatic biliary leakage following major upper abdominal surgery is a severe complication resulting in increased morbidity and mortality. Treatment options usually include either endoscopic intervention or surgical revision. These options may be burdened by a high perioperative risk for the patient (e.g., patients with severe disease) or simply may not be possible (e.g., nonpreserved gastroduodenal passage). In the past, percutaneous transhepatic cholangiodrainage did only seem to be a viable option for patients with dilated bile ducts. Here, we present our experience in a consecutive series of patients with symptomatic biliary leakage following major upper abdominal surgery and without dilation of the biliary system that underwent percutaneous transhepatic cholangiodrainage. Percutaneous transhepatic cholangiodrainage was feasible in 15 of 18 patients (83.3%). The procedure was technically not possible in three patients (16.7%). In 10 of the 15 patients (66.6%) with feasible percutaneous transhepatic cholangiodrainage, biliary leakage was definitely controlled without the need for surgical revision. Depending on the experience with the interventional procedure, percutaneous transhepatic cholangiodrainage should be considered as an alternative for treatment of symptomatic biliary leakage instead of immediate reoperation. Presented at the Digestive Disease Week 2005 (DDW), Chicago, IL, May 14–19, 2005 (poster presentation).  相似文献   
995.
Abstract Aggressive behaviour is rarely observed as an ictal semiology. Ictal aggression can occur in lesions of frontal and limbic structures. In limbic structure lesions, the main mechanism of aggressive behaviour is hyperactivity; whereas frontal lesions may cause aggressive behaviour with an indirect mechanism in which the suppression on limbic system is lost. Here we present a patient with ictal aggression. In this case a right frontoparietal epileptiform focus was detected during the postictal period. Magnetic resonance imaging showed cortical dysplasia on the right inferior frontal gyrus. The seizures disappeared completely after pharmacological treatment.  相似文献   
996.
Zusammenfassung Die Epilepsieforschung ist kein neues wissenschaftliches Feld—klinische und experimentelle Untersuchungen werden seit Jahrzehnten betrieben. Trotz dieser fortw?hrenden Bemühungen sind die Pathomechanismen der Epilepsie letztlich nicht vollst?ndig gekl?rt—allerdings gelangen in den letzten Jahren auch beachtliche Fortschritte. Vor allem durch die Kombination genetischer, molekularer und funktioneller Analysen konnten wichtige Teilaspekte der Entstehungsprozesse der Epilepsie aufgekl?rt werden. Der vorliegende übersichtsartikel soll nach einer kurzen Er?rterung der grunds?tzlichen Faktoren der Erregbarkeit einzelner Zellen und des neuronalen Zellverbandes in fünf kurzen Kapiteln einen überblick über den aktuellen Forschungsstand liefern. Innerhalb der ersten drei Abschnitte werden Ver?nderungen spannungsabh?ngiger Str?me, der synaptischen Transmission und deren Modulation sowie der Expression von Gap junctions beleuchtet. Darüber hinaus widmet sich ein Abschnitt morphologischen Ver?nderungen. Der letzte Teil behandelt Aspekte spezifischer genetischer Syndrome. Dieser Beitrag ist bereits in verkürzter Form in der Zeitschrift „Klinische Neurophysiologie“, Bd. 37 (2006), S. 1–9, unter dem Titel „Pathophysiologie der Epilepsie“ erschienen.  相似文献   
997.
ObjectiveTo assess the social disability of people with different psychiatric disorders.MethodsCross-site survey in five psychiatric hospitals (Dresden, Wrocław, London, Michalovce and Prague). Working-aged patients diagnosed (ICD-10) with schizophrenia and related disorders (F2), affective disorders (F3), anxiety disorders (F4), eating disorders (F5) and personality disorders (F6), were assessed at admission (n = 969) and 3 months after discharge (n = 753) using the Brief Psychiatric Rating Scale and the Groningen Social Disability Schedule. The main outcome measure was Interviewer-rated social disability.ResultsDuring acute episodes patients with personality, eating and schizophrenic disorders functioned less effectively than those with affective or anxiety disorders. After controlling for age and severity of psychopathology, there was no significant effect of the diagnosis (during remission), sex, education and history of disorder on disability. Site, employment and partnership were significant factors for the level of social disability in both measure points.ConclusionSeverity of psychopathological symptoms, not the diagnosis of a mental disorder, was the most significant factor in determining the level of social functioning, particularly during the remission period. Site, employment and partnership appeared as significant factors influencing the level of social disability.  相似文献   
998.
Eight-channel transmit/receive body MRI coil at 3T.   总被引:1,自引:0,他引:1  
Multichannel transmit magnetic resonance imaging (MR) systems have the potential to compensate for signal-intensity variations occurring at higher field strengths due to wave propagation effects in tissue. Methods such as RF shimming and local excitation in combination with parallel transmission can be applied to compensate for these effects. Moreover, parallel transmission can be applied to ease the excitation of arbitrarily shaped magnetization patterns. The implementation of these methods adds new requirements in terms of MRI hardware. This article describes the design of a decoupled eight-element transmit/receive body coil for 3T. The setup of the coil is explained, starting with standard single-channel resonators. Special focus is placed on the decoupling of the elements to obtain independent RF resonators. After a brief discussion of the underlying theory, the properties and limitations of the coil are outlined. Finally, the functionality and capabilities of the coil are demonstrated using RF measurements as well as MRI sequences.  相似文献   
999.
1000.
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