全文获取类型
收费全文 | 200255篇 |
免费 | 8385篇 |
国内免费 | 342篇 |
专业分类
耳鼻咽喉 | 3496篇 |
儿科学 | 7632篇 |
妇产科学 | 5377篇 |
基础医学 | 28203篇 |
口腔科学 | 6375篇 |
临床医学 | 15559篇 |
内科学 | 36150篇 |
皮肤病学 | 5027篇 |
神经病学 | 18520篇 |
特种医学 | 9754篇 |
外国民族医学 | 24篇 |
外科学 | 32289篇 |
综合类 | 1242篇 |
一般理论 | 39篇 |
预防医学 | 10436篇 |
眼科学 | 5054篇 |
药学 | 13846篇 |
中国医学 | 377篇 |
肿瘤学 | 9582篇 |
出版年
2021年 | 1539篇 |
2020年 | 1442篇 |
2019年 | 1724篇 |
2018年 | 3373篇 |
2017年 | 2813篇 |
2016年 | 3747篇 |
2015年 | 4127篇 |
2014年 | 4399篇 |
2013年 | 6433篇 |
2012年 | 9529篇 |
2011年 | 8969篇 |
2010年 | 5361篇 |
2009年 | 4492篇 |
2008年 | 8765篇 |
2007年 | 9739篇 |
2006年 | 9776篇 |
2005年 | 10210篇 |
2004年 | 9602篇 |
2003年 | 9483篇 |
2002年 | 9297篇 |
2001年 | 7172篇 |
2000年 | 7206篇 |
1999年 | 6325篇 |
1998年 | 1934篇 |
1997年 | 1610篇 |
1996年 | 1277篇 |
1995年 | 1094篇 |
1994年 | 1022篇 |
1992年 | 3148篇 |
1991年 | 3020篇 |
1990年 | 3024篇 |
1989年 | 2852篇 |
1988年 | 2536篇 |
1987年 | 2522篇 |
1986年 | 2303篇 |
1985年 | 2191篇 |
1984年 | 1781篇 |
1983年 | 1401篇 |
1982年 | 936篇 |
1979年 | 1734篇 |
1978年 | 1266篇 |
1977年 | 1057篇 |
1975年 | 1312篇 |
1974年 | 1367篇 |
1973年 | 1233篇 |
1972年 | 1228篇 |
1971年 | 1199篇 |
1970年 | 1074篇 |
1969年 | 976篇 |
1968年 | 962篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Abstract – Traumatic dental injuries often occur to the teeth and their supporting tissues and they are the main reasons for emergency visit to a dental clinic. Management of a fracture depends on its position and the extent of root involvement. Horizontal root fractures are not seen frequently and the treatment consists of reduction and long‐term rigid fixation of the coronal segment. The present case demonstrates the successful management of two horizontally fractured maxillary central incisors with a follow‐up period of 9 months. 相似文献
102.
Man Bok Jeong Kristina Narfström Shin Ae Park Je Min Chae Kang Moon Seo 《Documenta ophthalmologica. Advances in ophthalmology》2009,119(2):79-88
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
103.
104.
Dittmar Böckler Hardy Schumacher Klaus Klemm Marcel Riemensperger Philipp Geisbüsch Drosos Kotelis Harry Rotert Jens-Rainer Allenberg 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》2007,392(6):715-723
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
105.
Eser Tüfek?i Thomas E Merrill Maria R Pintado John P Beyer William A Brantley 《American journal of orthodontics and dentofacial orthopedics》2004,125(6):733-739
Teeth with white spot lesions (WSL) might be more prone to enamel loss during bracket debonding. This in vitro study compared enamel loss from teeth with (n = 14) and without (n = 14) WSL after polishing with low-speed finishing burs or disks (Sof-Lex, 3M ESPE, St Paul, Minn). Debonded surfaces were analyzed with a contact stylus profilometer, and digitized data were compared with baseline readings by using AnSur NT software (Regents, University of Minnesota, Minneapolis, Minn). Specimen surfaces were also examined with a scanning electron microscope. Two-way analysis of variance was performed to analyze the data. In teeth without WSL, the volume losses were 0.16 mm(3) for the bur group and 0.10 mm(3) for the disk group; the mean maximum depths were 47.7 microm for the bur group and 54.3 microm for the disk group. In teeth with WSL, the volume losses were 0.06 and 0.17 mm(3), and the mean maximum depths were 35.1 and 48.7 microm for the bur and disk groups, respectively. There were no significant differences in enamel loss between the 2 groups of teeth without WSL (P =.12). However, in teeth with WSL, the burs removed less enamel than the disks (P = 0.006). Scanning electron microscope examination showed that any damage on the enamel surface was usually located in the cervical third of the teeth. On most specimens, even though tooth surfaces appeared resin-free to the naked eye, there were remnants of it. The differences between groups were so small that they might be clinically insignificant. 相似文献
106.
Factor Xa-activated whole blood clotting time (Xa-ACT) for bedside monitoring of dalteparin anticoagulation during haemodialysis. 总被引:1,自引:1,他引:0
Rolf Dario Frank Vincent M Brandenburg Regina Lanzmich Jürgen Floege 《Nephrology, dialysis, transplantation》2004,19(6):1552-1558
BACKGROUND: Low molecular weight heparins (LMWH) like dalteparin are increasingly used for anticoagulation during haemodialysis (HD). The available laboratory tests for monitoring LMWH anticoagulation are time-consuming and expensive, and the suitability of the conventional activated clotting time (ACT) is controversial. A simple and cheap bedside test would be useful. METHODS: We studied the factor Xa-activated whole blood clotting time (Xa-ACT) in vitro and in vivo in nine patients undergoing chronic HD with i.v. dalteparin bolus anticoagulation and compared it with the conventional ACT. Plasma anti-factor Xa (antiXa) activity was determined with a chromogenic assay. Thrombin-antithrombin complexes were measured to detect coagulation activation. RESULTS: Xa-ACT and ACT were prolonged with rising dalteparin concentration. In vitro, both clotting times were strongly correlated with the antiXa levels (r = 0.94 and 0.89, respectively). Nevertheless, compared with the ACT, the Xa-ACT was considerably more sensitive to the LMWH in vitro (healthy blood: Xa-ACT 90 s/U vs ACT 26 s/U; uraemic blood: Xa-ACT 96 s/U vs ACT 31 s/U) as well as in vivo (Xa-ACT 81 s/U vs ACT 22 s/U) and reflected different intensities of anticoagulation. An initial dalteparin bolus of 80+/-11 U/kg body weight was able to prevent coagulation activation for up to 4 h of HD. CONCLUSION: For monitoring LMWH anticoagulation the Xa-ACT was superior to the conventional ACT in vitro as well as in vivo during HD. The Xa-ACT can be useful as a LMWH bedside test. The ACT was not sensitive enough to serve as a LMWH monitoring tool. 相似文献
107.
Zusammenfassung GRUNDLAGEN: Die endoskopische thorakale Sympathektomie (ETS) existiert seit 60 Jahren als effektive Therapie der primären Hyperhidrose. Nach wie vor gibt es in der medizinischen Welt teils Vorbehalte, teils Unwissen über die Methode selbst, ihre Erfolgs- und Komplikationsraten sowie Nebenwirkungen. METHODIK: Nach Einführung in die Symptome und Behandlung der primären Hyperhidrose (konservativ und chirurgisch) werden Operationsmethoden und Langzeitergebnisse der ETS-Operation vorwiegend anhand der Daten aus der eigenen Abteilung präsentiert. ERGEBNISSE: Von 1965–2001 wurden 734 Sympathikotomien (ETS2–4) und bis 2003 weitere 103 Sympathikusblockaden (ESB4) bei Patienten mit primärer palmarer und axillärer Hyperhidrose durchgeführt. Die Konversionsrate betrug 0,1 %. Seit Einführung der Video-Thorakoskopie 1991 trat kein postoperatives Horner-Syndrom auf (zuvor 2,2 %), Drainage-pflichtige Pneumothoraces waren in 1,1 % zu verzeichnen. Nach einem medianen Follow-up von 16 Jahren waren 93 % der Extremitäten trocken, 5 % fast trocken und 2 % feucht. Nebenwirkungen traten in Form von kompensatorischem Schwitzen am Stamm (55 % insgesamt, davon 5 % stark) und gustatorischem Schwitzen (33 %) auf. Seit Einführung der limitierten Sympathikusblockade auf Höhe T4 (ESB4) konnte (bei naturgemäß kurzer Nachbeobachtungszeit) das kompensatorische Schwitzen auf 8,5 % und das gustatorische Schwitzen auf 2,1 % gesenkt werden. Mit dem postoperativen Ergebnis waren 100 % der Patienten nach ESB4 zufrieden, nach ETS2–4 waren 80 % zufrieden, 14 % teilweise zufrieden und 6 % unzufrieden (meist wegen starken kompensatorischen Schwitzens). SCHLUSSFOLGERUNGEN: Die ETS-Operation bietet hohe langfristige Erfolgsraten bei niedrigen Komplikationsraten. Patienten sollten über die zu erwartenden Nebenwirkungen genau aufgeklärt werden, für unzufriedene Patienten mit starkem kompensatorischem Schwitzen besteht nun die Möglichkeit der thorakoskopischen Klip-Entfernung. 相似文献
108.
U. Bolm-Audorff S. Brandenburg T. Brüning H. Dupuis R. Ellegast G. Elsner K. Franz H. Grasshoff V. Grosser L. Hanisch B. Hartmann E. Hartung† K. G. Hering G. Heuchert M. Jäger J. Krämer Dr. A. Kranig E. Ludolph A. Luttmann A. Nienhaus W. Pieper K. D. Pöhl T. Remé D. Riede G. Rompe K. Schäfer S. Schilling E. Schmitt F. Schröter A. Seidler M. Spallek M. Weber 《Trauma und Berufskrankheit》2005,7(4):320-332
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
109.
Zusammenfassung Frakturen des proximalen Humerus stellen beim älteren Patienten, bedingt durch Osteopenie und Verletzungsschwere, eine Herausforderung für die operative Versorgung dar. Seit wenigen Jahren stehen intramedulläre Implantate zur Verfügung, mit denen auch Mehrfragmentfrakturen mit hoher Primärstabilität versorgt werden können. Bei limitierten Weichteilschäden kann durch frühe Physiotherapie ein gutes funktionelles Ergebnis erreicht werden. Seit 2003 verwenden wir den T2-PHN (Fa. Stryker) und konnten bisher 15 Patienten nach 1-jähriger Beobachtung auswerten. Bei einem Durchschnittsalter von 64,6 Jahren lag der durchschnittliche Constant-Score nach 1 Jahr bei 68,3 (±17,3) auf der betroffenen Seite, seitenadaptiert wurden 79% erreicht. Der Anteil der 4-Segment-Frakturen lag bei 60%. Bei 4 Patienten beobachteten wir eine partielle Humeruskopfnekrose ohne Therapiekonsequenz. Implantatentfernungen waren in 5 Fällen wegen überstehender Schrauben oder vorstehendem proximalem Nagelende nötig. Mit den modernen Verriegelungsmarknägeln ist eine Gewebe schonende und sehr stabile Versorgung der proximalen Humerusfrakturen möglich. 相似文献
110.
This prospective study investigated the effects of standard pharmacotherapy in out-of-hospital ventricular fibrillation (VF) after i.v. or endobronchial (e.b.) administration of epinephrine and lidocaine. METHODS. Only patients presenting with out-of-hospital VF were included in this study, whereby VF of noncardiac origin was excluded. Cardiopulmonary resuscitation (CPR) was performed according to the guidelines of the American Heart Association. Basic life support was initiated by Emergency Medical Service (EMS) technicians. The first step of advanced life support was immediate defibrillation by the EMS physician. Epinephrine was given in doses of 2.5 mg e.b. or 1.0 mg i.v. If indicated, patients received 200-500 mg lidocaine e.b. or 100 mg i.v. The course of CPR was tape-recorded and 2-3 blood samples were taken from each patient for drug monitoring. Plasma levels of epinephrine and lidocaine were measured by high-pressure liquid and gas chromatography, respectively, and then correlated to the course of CPR. RESULTS. Forty-seven patients presented VF on arrival of the EMS physician. Restoration of spontaneous circulation was achieved in 64% (Table 3), and 30% of the patients were discharged from hospital without major neurologic deficits. Immediate defibrillation before initiation of pharmacotherapy produced a success rate of 15.8%, whereas defibrillation after drug therapy was successful in 61.5% of cases. Following e.b. instillation of 2.5 mg epinephrine (Fig. 1), median peak concentrations of epinephrine (40.2, range 4.0-79.8 ng/ml) were reached after 3-4 min and plasma levels greater than or equal to 10 ng/ml were seen for 20 min. After i.v. injection of 1.0 mg epinephrine (Fig. 2) maximum concentrations (71.6, range 4.7-104.2 ng/ml) were measured after 1-2 min and plasma levels decreased below 10 ng/ml after 10 min. Following e.b. instillation of 400-500 mg lidocaine mean lidocaine concentrations within the therapeutic range (2-5 micrograms/ml) were reached after 4-5 min and remained within these limits for 20-30 min. Peak concentrations were obtained after 12 min. Doses of 200-320 mg lidocaine e.b. failed to achieve therapeutic plasma levels (Fig. 3). Regarding the pharmacodynamic aspects of drug therapy, 22.5% of the initial survivors were resuscitated from VF without therapeutic epinephrine, presenting with mean endogenous epinephrine concentrations of 7.1 ng/ml, 51.6% of patients were resuscitated after epinephrine therapy with plasma concentrations greater than 20 ng/ml. In only 1 case could a relationship be demonstrated between the administration of lidocaine and resuscitation success. CONCLUSION. In CPR, the e.b. administration of epinephrine and lidocaine is a reliable alternative to the i.v. injection route of these drugs. Recommended doses are 2.5 mg for epinephrine and 400-500 mg for lidocaine. Resuscitation from VF requires immediate epinephrine therapy if initial defibrillation is not successful. Lidocaine has no effect on resuscitation from VF and therefore should be used specifically for antiarrhythmic therapy after restoration of spontaneous circulation. 相似文献