全文获取类型
收费全文 | 17296篇 |
免费 | 977篇 |
国内免费 | 66篇 |
专业分类
耳鼻咽喉 | 235篇 |
儿科学 | 453篇 |
妇产科学 | 340篇 |
基础医学 | 2485篇 |
口腔科学 | 299篇 |
临床医学 | 1559篇 |
内科学 | 3464篇 |
皮肤病学 | 517篇 |
神经病学 | 2158篇 |
特种医学 | 991篇 |
外科学 | 2335篇 |
综合类 | 125篇 |
一般理论 | 4篇 |
预防医学 | 874篇 |
眼科学 | 288篇 |
药学 | 948篇 |
中国医学 | 62篇 |
肿瘤学 | 1202篇 |
出版年
2023年 | 150篇 |
2022年 | 244篇 |
2021年 | 441篇 |
2020年 | 295篇 |
2019年 | 418篇 |
2018年 | 446篇 |
2017年 | 402篇 |
2016年 | 498篇 |
2015年 | 496篇 |
2014年 | 687篇 |
2013年 | 822篇 |
2012年 | 1328篇 |
2011年 | 1400篇 |
2010年 | 805篇 |
2009年 | 702篇 |
2008年 | 1160篇 |
2007年 | 1143篇 |
2006年 | 1090篇 |
2005年 | 1082篇 |
2004年 | 922篇 |
2003年 | 875篇 |
2002年 | 788篇 |
2001年 | 146篇 |
2000年 | 119篇 |
1999年 | 165篇 |
1998年 | 185篇 |
1997年 | 134篇 |
1996年 | 133篇 |
1995年 | 89篇 |
1994年 | 90篇 |
1993年 | 62篇 |
1992年 | 47篇 |
1991年 | 51篇 |
1990年 | 36篇 |
1989年 | 24篇 |
1988年 | 29篇 |
1987年 | 30篇 |
1986年 | 24篇 |
1985年 | 28篇 |
1984年 | 23篇 |
1983年 | 22篇 |
1982年 | 30篇 |
1981年 | 23篇 |
1980年 | 35篇 |
1979年 | 24篇 |
1978年 | 21篇 |
1977年 | 31篇 |
1976年 | 18篇 |
1936年 | 15篇 |
1933年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
Helmut K. Wolf Matthias Spänle Marianne B. Müller Christian E. Elger Johannes Schramm Otmar D. Wiestler 《Acta neuropathologica》1994,88(4):313-319
Alterations of gamma aminobutyric acid (GABA)-mediated neurotransmission have been implicated in the pathogenesis of epilepsies. Here we examine the distribution of the GABAA receptor in the hippocampus of 78 surgical specimens from patients with chronic pharmacoresistant focal epilepsies. The receptor was localized immunohistochemically with the monoclonal antibody bd-24 which selectively recognizes the 1 subunit of the GABAA receptor. The results were compared with the receptor distribution of 28 normal hippocampal specimens obtained at autopsy. In the great majority of the surgical specimens a loss of GABAA receptor immunoreactivity was present in CA1 (92.3%), CA4 (78.2%), the dentate granular cell layer (70.5%) and the molecular layer of the dentate gyrus (65.4%). The subiculum revealed a normal staining pattern in all but 4 cases. In no instance did we observe an increase of immunoreactivity in any region or cell population. The decrease of GABAA receptor immunoreactivity was closely related to neuronal loss in the respective specimen and to Ammon's horn sclerosis. There was no correlation between GABAA receptor loss and the patient's age at surgery, duration of seizures, age at onset of seizures and to the presence or absence of secondary generalized tonic clonic seizures. The data suggest that the observed loss of GABAA receptor immunoreactivity is a secondary phenomenon rather than an event that is relevant for the pathogenesis of epileptic seizures. 相似文献
162.
Dr. Martin Scholz Stefanie Märzheuser-Brands Joachim Gottschalk Johannes C. Böck Wolfgang R. Lanksch 《Neurosurgical review》1994,17(1):89-93
The authors add to the literature a case report of a 32-year-old man with an intramedullary epidermoid cyst at the level of D 3/4, that was successfully operated on. There are several previous reports in the literature, but only five of these include MRI studies. 相似文献
163.
Manke C Geissler A Seitz J Lenhart M Kasprzak P Gmeinwieser J Feuerbach S 《Cardiovascular and interventional radiology》1999,22(2):141-143
Stent placement is a widely used bail-out treatment for dissection of peripheral arteries. Below the level of the superficial femoral artery permanent stenting is complicated by a high incidence of subacute thrombosis and restenosis. We present two cases of arterial occlusion due to acute iatrogenic dissection of the popliteal and distal fibular arteries. Successful treatment was achieved with a new bail-out procedure. Strecker stents were implanted to seal off the dissection flap. Stents were retrieved easily after 24 hr using a myocardial biopsy forceps. After stent retrieval the temporarily stented segments were patent and showed a larger lumen compared with segments treated by balloon dilatation alone. Temporary stenting is a simple and safe procedure and offers the advantage of tacking up dissection membranes and preventing recoil. Persistent presence of a metallic implant as a source of continued injury and stimulus for intimal proliferation is avoided. 相似文献
164.
Traumatic brain and spinal cord injuries are severe burdens for the patients, their relatives, the health care providers and society as a whole. Recent data demonstrate the magnitude of the problem: It is mostly a disease of the young gen-eration (age 20-45 years) with mortality rates for severe traumatic brain injury (TBI) between 40-50%. In approximately 60% of cases, multiple trauma is accompanied by head injury. The outcome of TBI is determined not only by the extent and severity of the primary insult, but also by the degree of secondary brain damage. In the subgroup of severe TBI (GCS=8) only 25%t of patients showed a complete recovery or had minor neurological deficits; 15% resulted in a lifelong disability or even in a permanent vegetative state. Economically, the impact of TBI is enormous - estimates of the costs of TBI in the U.S. range from 4-15 billion dollars per year. Valid data for Germany are not yet available. 相似文献
165.
Johannes CB Stellato RK Feldman HA Longcope C McKinlay JB 《Journal of clinical epidemiology》1999,52(2):95-103
Low circulating levels of the adrenal steroids dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) are thought to be associated with increased risk of cardiovascular disease (CVD) in men. In women, either a positive or null association with CVD has been found. The nature of the relation between DHEAS and CVD risk factors in women is unclear and is based on cross-sectional data. We present results from a longitudinal investigation of serum DHEA and DHEAS and cardiovascular disease risk factors in 236 women, initially 50-60 years old, from a population-based prospective (1986-1995) study of the menopausal transition. We used generalized estimating equations to model the relation of serum DHEA and DHEAS to systolic and diastolic blood pressure and serum levels of total cholesterol, high density lipoprotein cholesterol, and apolipoproteins A and B, adjusting for other factors related to CVD. Both DHEA and DHEAS were positively related to diastolic and systolic blood pressure, and DHEAS was negatively related to apolipoprotein A. DHEA and DHEAS were also positively related to smoking, alcohol use, estrone, and estradiol levels, and inversely related to age. Our results suggest that higher levels of DHEA and DHEAS in middle-aged women may indicate increased CVD risk. 相似文献
166.
Striatal dopamine transporter density in major depression 总被引:4,自引:0,他引:4
Teijamari Laasonen-Balk Jyrki Kuikka Heimo Viinamäki Minna Husso-Saastamoinen Johannes Lehtonen Jari Tiihonen 《Psychopharmacology》1999,144(3):282-285
Rationale: There are no previous data available regarding [123I]β-CIT binding to the dopamine transporter sites in the basal ganglia in depressed patients. Objective: The present study tested the hypothesis that the brain DAT density in depressed patients is lower than that in matched healthy
controls. Methods: Fifteen drug-naive outpatients with major depression and 18 healthy controls were investigated using single photon emission
computerized tomography (SPECT) with a high-affinity dopamine transporter specific radioligand, 123I-labeled β-CIT (2β-carbomethoxy-3β-(4-iodophenyl)-tropane). Results: We found a significantly higher [123I]β-CIT uptake in both sides of the basal ganglia in patients with major depression than in the controls (Mann-Whitney U-test, P = 0.002 on the right and P = 0.003 on the left). Conclusions: The radioligand uptake reflecting the DAT density was significantly higher among the patients than in the controls. This
finding is unexpected, since it is generally believed that monoaminergic neurotransmission is lower in depression, and therefore
it could be assumed that a reduction in dopamine transmission would lead to secondary down-regulation of DAT density. However,
it is possible that up-regulation of the DAT may be the primary alteration, which leads to lower intrasynaptic dopamine concentration
and to lower dopamine neural transmission.
Received: 20 October 1998/Final version: 25 January 1999 相似文献
167.
Achim Schmoldt Ingbert Blömer Andrea Johannes 《Naunyn-Schmiedeberg's archives of pharmacology》1992,346(2):226-233
Summary In vitro experiments were performed with cytosolic and microsomal fractions of human liver specimens in order to investigate which enzyme forms of sulfotransferase (ST) and UDP-glucurosyltransferase (GT) are involved in the metabolism of digitoxin (dt-3) and/or its cleavage products. It was found that the cytosolic STs preferentially react with digitoxigenin (dt-0) whereas microsomal GTs conjugate digitoxigenin-monodigitoxoside (dt-1) and in traces the bisdigitoxoside (dt-2). Dt-3 and dt-0 cannot be glucuronidated. By separation of different sulfotransferases it was found that the hydroxysteroid-ST is responsible for dt-0 and 3-epidigitoxigenin (epi-dt-0) sulfation. The hydroxysteroid-ST could be purified and characterized (apparent Km and Vmax for dt-0 sulfation: approx. 17 mol/l and 2.7 nmol/min mg protein, respectively). Of various model substrates and endogenous compounds (steroids, bilirubin) none caused a competitive inhibition of the microsomal dt-1 glucuronidation except dt-2 and dt-3. Therefore it can be supposed that a new GT form catalyses this reaction. It is characterized by an extraordinarily high affinity towards dt-1 with Km values ranging between 0.7 and 27 mol/l.Abbreviations DHEA
dehydroepiandrosterone
- dg-0
digoxigenin
- dg-1
digoxigenin-monodigitoxoside
- dt-0
digitoxigenin
- dt1
digitoxigenin-monodigitoxoside
- dt-2
digitoxigenin-bisdigitoxoside
- dt-3
digitoxigenin-trisdigitoxoside, digitoxin
- epi-dt-0
3-epi-digitoxigenin
- GT
UDP-glucuronosyltransferase
- PAPS
3-phosphoadenosine-5-phosphosulfate
- ST
sulfotransferase
- UDPGA
UDP-glucuronic acid
Send offprint requests to A. Schmoldt at the above address 相似文献
168.
Johannes Pill Alfred Völkl Franz Hartig H. Dariush Fahimi 《Archives of toxicology》1992,66(5):327-333
The effects of bezafibrate administered at 10 and 50 mg/kg/day for 7 days to male Sprague-Dawley (SD) and Lewis rats were investigated in order to determine the interrelation between the changes in serum and hepatic lipid contents and activities of selected peroxisomal, microsomal and mitochondrial enzymes in the two rat strains. In both strains, bezafibrate effectively reduced serum and hepatic lipids, increased the liver weight, induced a proliferation of peroxisomes, and selectively elevated the activities of carnitine acetyltransferase and of the enzymes of the peroxisomal -oxidation system. Moreover, immunoblotting revealed that the drug specifically enhanced the concentration of only those peroxisomal enzymes involved in fatty acid -oxidation. The data obtained demonstrate that although the responses initiated by bezafibrate are qualitatively similar in both strains, they differ in their magnitude in a dose-dependent manner, with the Lewis strain exhibiting a more pronounced response than the SD rats. These results show that dose-dependent strain differences as well as the generally known species differences should be taken into account in pharmacological and toxicological evaluations of fibrates in rodents. Furthermore, generalization and extrapolation from rodent studies should be treated with great caution. 相似文献
169.
Johannes Lammer Ernst Pilger Günter E. Klein Klaus Hausegger Fritz Flückiger 《Lasers in medical science》1991,6(3):311-315
Laser recanalization of peripheral artery occlusions was performed in 338 patients. A continuous wave Nd-YAG laser was used in combination with sapphire-probe laser catheters. The initial recanalization rate was 85%. Complications such as dissections, perforations, emboli and spasm were observed in 14%. The cumulative patency rate after 3 years was 48%. 相似文献
170.
Summary The operative correction of the pathological flat acetabulum in congenital dislocation of the hip, myelodysplasia and cerebral palsy can be performed with pelvic osteotomies and acetabuloplasties. In the light of our own experiences gained with different methods we prefer the pericapsular osteotomy of the ilium according to Pemberton since 1971. After the evaluation of the results the advantages of the method compared with other procedures are presented in the light of the improvements of correction and the rate of complication.
Zusammenfassung Die operative Korrektur der Flachpfannen bei Luxationshüfte, Myelodysplasie und Zerebralparese kann mittels Beckenosteotomie oder Azetabuloplastik erzielt werden. Anhand eigener Erfahrungen mit verschiedenen Methoden wird seit 1971 die perikapsuläre Iliumosteotomie nach Pemberton bevorzugt. Nach Auswertung der Ergebnisse werden die Vorteile der Methode gegenüber den anderen Verfahren anhand des Korrekturgewinnes und der Komplikationsrate dargelegt.相似文献