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   174266篇
  免费   6579篇
  国内免费   331篇
耳鼻咽喉   3096篇
儿科学   6490篇
妇产科学   4429篇
基础医学   24656篇
口腔科学   4913篇
临床医学   12970篇
内科学   31590篇
皮肤病学   4850篇
神经病学   16066篇
特种医学   8941篇
外国民族医学   24篇
外科学   28855篇
综合类   1104篇
一般理论   38篇
预防医学   8133篇
眼科学   4672篇
药学   12024篇
中国医学   347篇
肿瘤学   7978篇
  2021年   1284篇
  2020年   1143篇
  2019年   1337篇
  2018年   2897篇
  2017年   2383篇
  2016年   3352篇
  2015年   3720篇
  2014年   3919篇
  2013年   5494篇
  2012年   8471篇
  2011年   7869篇
  2010年   4675篇
  2009年   3767篇
  2008年   7809篇
  2007年   8674篇
  2006年   8705篇
  2005年   9112篇
  2004年   8670篇
  2003年   8567篇
  2002年   8458篇
  2001年   6339篇
  2000年   6389篇
  1999年   5545篇
  1998年   1619篇
  1997年   1346篇
  1996年   1022篇
  1995年   825篇
  1994年   767篇
  1992年   2447篇
  1991年   2381篇
  1990年   2333篇
  1989年   2189篇
  1988年   1896篇
  1987年   1909篇
  1986年   1768篇
  1985年   1679篇
  1984年   1319篇
  1983年   1047篇
  1979年   1407篇
  1978年   1026篇
  1977年   889篇
  1975年   1102篇
  1974年   1148篇
  1973年   1053篇
  1972年   1052篇
  1971年   1026篇
  1970年   910篇
  1969年   863篇
  1968年   823篇
  1967年   768篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
91.
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   
92.
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   
93.
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   
94.
Solid lipid nanoparticles (SLN), an alternative colloidal drug delivery system to polymer nanoparticles, emulsions and liposomes, are generally produced by high pressure melt-emulsification. However, the harsh production process is not applicable for formulations containing shear and temperature sensitive compounds. For that reason, subsequent adsorptive SLN loading might be a promising alternative. The aim of the present study was the development and characterisation of surface-modified SLN for adsorptive protein loading by variation of both the lipid matrix and the emulsifier concentration in the continuous phase. Variations in SLN composition resulted in particle sizes between 674 and 61 nm corresponding to specific surfaces of 4.5 m(2)/g and 48.9 m(2)/g and zeta potentials between -23.4 mV and -0.9 mV. In dependence of SLN surface properties, albumin payload ranged from 2.5 to 15%. Thermoanalysis, X-ray diffraction and electron microscopy revealed anisometrical and crystalline particles. In vitro cytotoxicity was low in terms of both haemolysis, which was between 1 and 2%, and neutral red test (NRT) showing a half lethal dose between 1.1 and 4.6%.  相似文献   
95.
Abstract 10 embalmed cadaver forearms and wrists were dissected to determine the anatomical course of the superficial branch of the radial nerve in the distal forearm. The superficial radial nerve bifurcated in two branches at a mean of 54,7 mm proximal to the radial styloid. From the styloid process of the radius, the mean distance to the closest dorsal branch of the superficial radial nerve was 3,5 mm and the mean distance to the closest volar branch was 9,8 mm. The mean distance between the closest branch of the superficial radial nerve and Lister?s tubercle was 16,4 mm. The crossing point between the nerve and the cephalic vein was located at a mean of 54,3 mm proximal to the styloid process. At the level of styloid process the mean distance between the closest dorsal branch of the superficial radial nerve and the first dorsal compartment was 15,2 mm and between the closest volar branch and the first dorsal compartment 4,4 mm. Detailed knowledge of anatomic characteristics of the superficial branch of the radial nerve may help prevent injury during operations and treat traumatic lesions of the nerve. Because of great variations in the course of the superficial radial nerve we could not define an absolute safe zone for surgical procedures on the distal forearm. Iatrogenic lesions of the superficial radial nerve are described complications of percutaneous procedures. Therefore open surgical approaches are recommended. Daniela Klitscher and Lars Peter Müller contributed equally to this work.  相似文献   
96.
Results of total and subtotal colon resections in children.   总被引:2,自引:0,他引:2  
AIM: The treatment of long-segment neuronal intestinal malformations confronts the paediatric surgeon with the problems of diagnosis, suitable surgical methods and postoperative care. The evidence based only on ganglion cells is inadequate to decide about the required extent of resection and does not exclude hypoganglionosis and disseminated dysganglionosis. For the surgical treatment, pouch procedures as well as the usual resection techniques according to Rehbein, Soave, and Duhamel are discussed. Since studies with greater numbers of patients are rare, we present here our own results. METHODS: 48 patients with long segment intestinal malformations were treated in our hospital between 1990 and 2000. A total of 35 patients were examined 1.5-6 years after definitive surgical therapy. Rehbein's anterior resection was performed in all cases. RESULTS: Our findings showed that the surgical treatment with Rehbein's technique offers good results, both with respect to complications as well as to the postoperative course, although a 4 cm long aganglionic segment remains in situ. We found that results were better after ascendorectostomy (n = 22) compared to ileorectostomy (n = 11). Earlier publications of this group (13) show that the histology of the proximal resection margin is decisive for the prognosis. Hypo- and aganglionic segments should be completely resected while short IND segments of the colon or terminal ileum may remain in situ. However, the additional effect of the aganglionic segment of the distal rectum and the decreased peristaltic flow of the pre-anastomotic bowel has to be taken into account. Further investigations are required to find out whether a combination of Soave's endorectal pull-through with a remaining neuronal dysplastic segment proximal to the resection margin may give better results or if the frequency of postoperative enterocolitis and incontinence increased in cases of long segment intestinal neuronal malformations. Accurate diagnosis of myenteric plexus is decisive for an optimal treatment and therefore, considering our results, it is essential that in case of newborns getting to hospital with colon obstruction and suspicion of neuronal intestinal malformation full thickness biopsies from the distal and proximal colon may be taken simultaneously with the enterostomy. Generally ileostomy is performed in patients suspected of long-segment neuronal intestinal malformations. Mucosa suction biopsies from the distal and proximal stoma side are less informative compared to full thickness biopsies.  相似文献   
97.
98.
99.
100.
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