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   141553篇
  免费   6930篇
  国内免费   126篇
耳鼻咽喉   2359篇
儿科学   4842篇
妇产科学   3302篇
基础医学   21126篇
口腔科学   4746篇
临床医学   11720篇
内科学   25710篇
皮肤病学   4125篇
神经病学   14370篇
特种医学   6078篇
外国民族医学   4篇
外科学   21561篇
综合类   701篇
一般理论   41篇
预防医学   7833篇
眼科学   3084篇
药学   9567篇
  1篇
中国医学   260篇
肿瘤学   7179篇
  2023年   853篇
  2022年   561篇
  2021年   1391篇
  2020年   1242篇
  2019年   1515篇
  2018年   3099篇
  2017年   2638篇
  2016年   3373篇
  2015年   2956篇
  2014年   3267篇
  2013年   5705篇
  2012年   7294篇
  2011年   8226篇
  2010年   4631篇
  2009年   3107篇
  2008年   8216篇
  2007年   8646篇
  2006年   8358篇
  2005年   8248篇
  2004年   7757篇
  2003年   7775篇
  2002年   7673篇
  2001年   5370篇
  2000年   6817篇
  1999年   3806篇
  1998年   1504篇
  1997年   1229篇
  1996年   983篇
  1995年   815篇
  1994年   777篇
  1993年   753篇
  1992年   760篇
  1991年   636篇
  1990年   611篇
  1989年   648篇
  1988年   522篇
  1987年   597篇
  1986年   503篇
  1985年   707篇
  1984年   677篇
  1983年   581篇
  1982年   602篇
  1981年   570篇
  1980年   546篇
  1979年   505篇
  1978年   461篇
  1977年   490篇
  1976年   408篇
  1975年   422篇
  1974年   396篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The objective of this study is to compare the effects of three different anesthetic combinations on the electroretinogram in the same animals under similar laboratory conditions. Thiopental–isoflurane (TI), medetomidine–ketamine (MK), and xylazine–ketamine (XK) were used on each of 12 healthy miniature schnauzer dogs (MS) with a period of at least 3 weeks in between subsequent anesthesia protocols, using the Dog Standard Protocol. The scotopic ERGs consisted of scotopic low stimulus strength (S) responses designated S1, S2, S3, S4, and S5, at 1, 5, 10, 15, and 20 min after dark adaptation, respectively, and scotopic standard stimulus strength (S-ST) responses. The photopic ERGs consisted of a photopic single flash (P) response and 31 Hz flicker (P-FL) responses. For S-ST (2.5 cd s/m2), the amplitude of the a-wave using TI was significantly lower than that using MK (adjusted P = 0.05) and XK (adjusted P = 0.03), and the implicit time of the a-wave was significantly shorter than that using MK (adjusted P = 0.04). For P (2.5 cd s/m2), the amplitude of the b-wave using XK was significantly higher than that using MK (adjusted P = 0.01). The implicit times of the b-wave using TI was significantly longer and shorter than that of MK for S1, S2 and P-FL and for S4 and S-ST, respectively, and than that of XK for S2 and P-FL and for S5 and S-ST, respectively. The results of the present study showed that TI affected both the amplitude and the implicit time of the a-wave for S-ST and the implicit time of the b-wave relatively more so than was the case when using XK or MK. Therefore, it appears that either XK or MK could be advantageous to use rather than TI for clinical studies.  相似文献   
72.
73.
OBJECTIVES: to report our experience with hybrid vascular procedures in patients with pararenal and thoracoabdominal aortic pathologies. METHODS: 68 patients were treated for thoracoabdominal aortic pathologies between October 1999 and February 2004; 19 patients (16 men; mean age 68, range 40-79) with high risk for open thoracoabdominal repair were considered to be candidates for combined endovascular and open repair. Aortic pathologies included five thoracoabdominal Crawford I aneurysms, one postdissection expanding aneurysm, three symptomatic plaque ruptures (Crawford IV), five combined thoracic descending and infrarenal aneurysms with a healthy visceral segment, three juxtarenal or para-anastomotic aneurysms, and two patients with simultaneous open aortic arch replacement and a rendezvous maneuver for thoracic endografting. Commercially available endografts were implanted with standardized endovascular techniques after revascularization of visceral and renal arteries. RESULTS: Technical success was 95%. One patient developed a proximal type I endoleak after chronic expanding type B dissection and currently is waiting conversion. Nine patients underwent elective, five emergency and five urgent (within 24 h) repair. 17 operations were performed simultaneously, and 2 as a staged procedure. Postoperative complications include two retroperitoneal hemorrhages, and one patient required long-term ventilation with preexisting subglottic tracheal stenosis. Thirty-day mortality was 17% (one multiple organ failure, one secondary rupture after open aortic arch repair, one myocardial infarction). Paraplegia or acute renal failure were not observed. Total survival rate was to 83% with a mean follow-up of 30 months. CONCLUSIONS: Midterm results of combined endovascular and open procedures in the thoracoabdominal aorta are encouraging in selected high risk patients. Staged interventions may reduce morbidity.  相似文献   
74.
Heparin-induced thrombocytopenia (HIT) represents a serious side effect caused by an atypical immune response to platelet factor 4 leading to platelet activation and thrombin formation. These patients are at high risk of thromboembolism, with a rapid drop in platelet count between days 5 and 14 after the initiation of heparin treatment. In single cases, especially after major surgery, platelet count reduction might be absent or hidden by preceding thrombocytosis. Different clinical manifestations of HIT include unspecific skin reactions with potential necrosis at the site of heparin injection, mostly after the application of unfractionated heparin but also with low molecular weight heparin. In heparin-induced skin necrosis, administration of unfractionated or low molecular weight heparin is contraindicated and heparin therapy should be stopped immediately. Instead, an alternative anticoagulant in the form of a direct thrombin inhibitor such as argatroban, and respectively lepirudin, or danaparoid sodium must be administered. Due to frequent misinterpretations of heparin-induced unspecific skin reactions, especially in the absence of thrombocytopenia, we present two case reports which should increase the awareness of HIT’s various clinical pictures.  相似文献   
75.
The first part of this serial paper dealt with the medical criteria used in evaluation of the clinical picture caused by physical stress and the evaluation of other candidate causes and was published in issue no. 3/2005 (pp. 711–752) of Trauma and Berufskrankheit. This follow-up paper (II) presents criteria to be used in the evaluation of whether it is necessary to give up the occupations putting the spine at risk and in estimation of the degree of disability.  相似文献   
76.
77.
Migraine is considered to be a functional neurological disorder. In classical migraine (headache associated with prodromal visual field disturbances) and migraine accompagnée (headache associated with transient neurological symptoms), disturbances of cerebral blood flow and amine metabolism are thought to be pathogenetic factors. However, conventional methods of neuroimaging (CAT, NMR) usually do not yield any pathological findings in patients. Since 123I-iodoamphetamine (123I-IMP) crosses the intact blood brain barrier, 123I-IMP-SPECT is used for the assessment of cerebral perfusion in various neurological diseases, including functional disorders. 123I-IMP-SPECT was performed on 5 patients with classical migraine and 18 patients with migraine accompagnée. At the time of investigation, all patients were symptom-free. Cerebral blood flow was decreased in all patients with migraine accompagnée, and often corresponded to the site of headache as well as to the topography of transient neurological symptoms. This reduction was most obvious in a patient with persisting neurological symptoms. Most patients with classical migraine, however, did not show any alteration of cerebral perfusion. It appears that migraine--and in particular migraine accompagnée--is characterized by a permanent alteration not only of cerebral blood flow but also of neuronal activity. Migraine attacks may occur in connection with exacerbations of preexisting metabolic alterations.  相似文献   
78.

Background  

The telomeric region of mouse chromosome 12 has previously shown frequent allelic loss in murine lymphoma. The Bcl11b gene has been identified and suggested as a candidate tumor suppressor gene within this region. In this study, we aimed to elucidate whether Bcl11b is mutated in lymphomas with allelic loss, and whether the mutations we detected conferred any effect on cell proliferation and apoptosis.  相似文献   
79.
ZusammenfassungEinleitung In unserer Klinik wird seit über 30 Jahren die operative Behandlung von Klumpfüßen über einen dorsomedialen Zugang durchgeführt. Postoperativ erfolgt zunächst eine Gipsbehandlung, dann eine konsequente Nachbehandlung mit Orthesen und Winkeleinlagen.Material und Methode Zwischen dem 1. 6. 1986 und dem 31. 12. 2000 wurden 130 primäre Klumpfußweichteiloperationen bei 86 Patienten durchgeführt. 119 (92%) Füße konnten nach durchschnittlich 4,5 Jahren klinisch-radiologisch nachuntersucht werden. Das durchschnittliche Alter bei der Operation betrug 7,6 Monate. Klassifikation nach Dimeglio und Score nach Laaveg und Ponseti dienten zur Beurteilung. Die gemessenen Winkel in den belasteten Röntgenbildern des Fußes a.p. und seitlich prä- und postoperativ wurden verglichen, Komplikationen und Rezidive dokumentiert.Ergebnisse 29 (22,3%) Füße wiesen einen Schweregrad IV nach Dimeglio, 58 (44,6%) Grad III und 43 (33,1%) Grad II auf. Ein Klumpfußrezidiv war bei 9 (7,6%) Fällen zu beobachten. Alle Winkel verbesserten sich signifikant. Bei der Nachuntersuchung wurden durchschnittlich 95,4±9,2 Punkte nach dem Score von Laaveg und Ponseti erzielt.Schlussfolgerung Der von uns verwendete dorsomediale Zugangsweg erlaubt eine ausgezeichnete Klumpfußkorrektur mit geringer Rezidiv- und Komplikationsrate.  相似文献   
80.
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