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   28851篇
  免费   1714篇
  国内免费   58篇
耳鼻咽喉   400篇
儿科学   745篇
妇产科学   574篇
基础医学   4762篇
口腔科学   604篇
临床医学   2712篇
内科学   5581篇
皮肤病学   556篇
神经病学   2386篇
特种医学   1580篇
外国民族医学   25篇
外科学   3519篇
综合类   229篇
一般理论   6篇
预防医学   2488篇
眼科学   467篇
药学   2537篇
中国医学   72篇
肿瘤学   1380篇
  2022年   183篇
  2021年   345篇
  2020年   224篇
  2019年   314篇
  2018年   386篇
  2017年   307篇
  2016年   364篇
  2015年   445篇
  2014年   580篇
  2013年   848篇
  2012年   1260篇
  2011年   1361篇
  2010年   768篇
  2009年   770篇
  2008年   1248篇
  2007年   1320篇
  2006年   1320篇
  2005年   1291篇
  2004年   1211篇
  2003年   1172篇
  2002年   1105篇
  2001年   795篇
  2000年   830篇
  1999年   727篇
  1998年   330篇
  1997年   295篇
  1996年   237篇
  1995年   232篇
  1994年   268篇
  1993年   312篇
  1992年   703篇
  1991年   657篇
  1990年   549篇
  1989年   388篇
  1988年   363篇
  1987年   346篇
  1986年   314篇
  1985年   343篇
  1984年   264篇
  1983年   197篇
  1982年   163篇
  1981年   162篇
  1979年   216篇
  1978年   180篇
  1977年   164篇
  1976年   176篇
  1975年   179篇
  1974年   218篇
  1973年   188篇
  1972年   158篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
The US economic and social costs of Alzheimer's disease revisited.   总被引:13,自引:2,他引:11       下载免费PDF全文
OBJECTIVEs. An earlier paper estimated the per-case and national incidence costs of Alzheimer's disease for 1983. This paper updates the estimates of costs per case to 1991 and presents new national prevalence estimates of the economic and social costs of the disease. METHODS. All data for the cost estimates were taken from published sources or provided by other researchers. RESULTS. At midrange values of the estimated cost and epidemiological parameters, the discounted (at 4%) direct and total costs of Alzheimer's disease were $47,581 and $173,932 per case, respectively. The estimated 1991 national direct and total prevalence costs were $20.6 billion and $67.3 billion, respectively. Assuming conservatively that the prevalence of the disease remains constant, the estimated discounted present values of the direct and total costs of all current and future generations of Alzheimer's patients are $536 billion and $1.75 trillion, respectively. CONCLUSIONS. The $536 billion and $1.75 trillion figures are minimum estimates of the long-term dollar losses to the US economy in 1991 caused by Alzheimer's disease.  相似文献   
32.
Acute CyA nephrotoxicity involves alteration in the proximal tubule and leads to glomerular lesions. Administration of a vasodilatator agent such as the prostaglandin E1 analogue Rioprostil (Bayer AG, BAY 06893) might prevent preglomerular vasoconstriction and hence reduce cyclosporin nephrotoxicity. As an increased excretion of urinary enzymes as a consequence of CyA-nephrotoxicity is well known we investigated in 40 male Wistar rats the excretion of three urinary enzymes: the brush border enzyme gamma-glutamyltransferase (GGT), the leucine aminopeptidase (LAP), and the lysosomal enzyme N-acetyl-beta-glucosaminidase (NAG). Additionally we determined s-creatinine and CyA plasma level. The kidneys were studied histologically at the end of the study. Wistar rats receiving 20 or 50 mg CyA/kg/d showed a marked deterioration in renal function and an increase of all urinary enzymes determined. In the rats receiving 20 mg CyA/kg/d and Rioprostil (150 micrograms/d) renal function and the enzymes determined remained in the normal range. There was no change in the enzyme excretion and only a minor improvement of renal function in rats receiving 50 mg CyA/kg/d and Rioprostil. Histological findings showed prevention of CyA nephrotoxicity in the 20 mg/kg/d group and diminished renal damage in the 50 mg/kg/d group.  相似文献   
33.
34.
Tissue distribution, disposition, and metabolism of 3H-cyclosporine were studied in rats after single and repeated oral doses of 10 and 30 mg/kg and after an iv dose of 3 mg/kg. The oral doses of 10 and 30 mg/kg were dissolved in polyethylene glycol 200/ethanol or in olive oil/Labrafil/ethanol. Absorption from both formulations was slow and incomplete, with peak 3H blood levels at 3-4 hr. Approximately 30% of the radioactive dose was absorbed, which is consistent with oral bioavailability data for cyclosporine. More than 70% of the radioactivity was excreted in feces and up to 15% in urine. Elimination via the bile accounted for 10 and 60% of the oral and iv doses, respectively. Since unchanged cyclosporine predominated in both blood and tissues at early time points, the half-lives of the distribution phases (t 1/2 alpha) of parent drug and of total radioactivity were similar. In blood, kidney, liver, and lymph nodes, t 1/2 alpha of cyclosporine ranged from 6-10 hr. Elimination of radioactivity from the systemic circulation was multiphasic, with a terminal half-life of 20-30 hr. 3H-Cyclosporine was extensively distributed throughout the body, with highest concentrations in liver, kidney, endocrine glands, and adipose tissue. The concentrations of both total radioactivity and parent drug were greater in tissues than in blood, which is consistent with the high lipid solubility of cyclosporine and some of its metabolites. Skin and adipose tissue were the main storage sites for unchanged cyclosporine. Elimination half-lives were slower for most tissues than for blood and increased with multiple dosing. The amount of unchanged drug was negligible in urine and bile.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
35.
Bone morphogenetic proteins (BMPs) are bone growth factors, which regulate bone formation during fetal development and bone repair after injury in postfetal life. Since 1992 BMP-7 has been produced by recombinant technique (rhBMP-7). Numerous animal models and clinical trials have shown that rhBMP-7 can induce de novo bone formation in segmental defects of bones and in cases of nonunion. Since 2001 rhBMP-7 has been approved for treatment of tibial nonunion in Europe. The effect of rhBMP-7 is comparable to the clinical and radiological results achieved with bone autografts. The problem of donor site morbidity (which occurs in up to 20% of all cases) is eliminated by the use of BMP-7. Long-term results and experience in clinical practice are not yet available.  相似文献   
36.
EMPACT syndrome     
Background: Seizure prophylaxis with phenytoin is a common measure in oncologic patients with brain metastases. In these patients, generalized severe adverse drug reactions such as erythema multiforme (EEM) may occur. However, in a subgroup of patients with brain radiation therapy, EEM‐like lesions develop particularly in the radiation field. Most recently, the acronym EMPACT ( E rythema M ultiforme associated with P henytoin A nd C ranial radiation T herapy) was proposed to specifically describe this syndrome. Patient/Method: Here, we report on EMPACT syndrome in a 46‐year‐old woman. Therapeutic measures included seizure prophylaxis with phenytoin and total brain radiation therapy of brain metastases from bronchial carcinoma. Three weeks after introduction of phenytoin, the patient presented with EEM‐like skin lesions restricted to the original radiation field and facial mucocutaneous involvement. After a few days, the rash spread to the upper part of the body. She was also in poor general condition. Results: The immediate cessation of phenytoin therapy, combined with administration of systemic corticosteroids and high dose immunoglobulins along with intensive local treatment and pain medications, resulted in complete resolution of the skin eruption. Patch testing to phenytoin was positive after 72 hours. Conclusion: EMPACT should be classified as an specific entity among the EEM‐like drug reactions as it only appears after radiotherapy and seizure prophylaxis with the anticonvulsant phenytoin. We propose including specific type IV‐sensitization to phenytoin into the definition of EMPACT.  相似文献   
37.
B M Psaty  T D Koepsell  J P LoGerfo  E H Wagner  T S Inui 《JAMA》1989,261(14):2087-2094
We conducted a population-based, case-control study to determine whether beta-blockers, used for the treatment of hypertension, prevent first events of coronary heart disease. Cases were patients who had high blood pressure treated with medicines and who presented in 1982 to 1984 with angina or fatal or nonfatal myocardial infarction. Controls were a probability sample of health maintenance organization patients with pharmacologically treated hypertension and free of coronary heart disease. Blinded to case-control status, we reviewed the medical records of the 248 cases and 737 controls. The health maintenance organization's computerized pharmacy database was used to ascertain the use of beta-blockers. Fewer cases than controls were taking beta-blockers. This difference was confined to those with nonfatal infarctions. After adjustment for confounding, the estimated relative risk was 0.62 (95% confidence interval, 0.39 to 0.99). Higher doses of beta-blockers conferred greater protection. We conclude that beta-blockers may prevent first events of nonfatal myocardial infarction in patients with high blood pressure.  相似文献   
38.
Zusammenfassung Die Humerusschaftfraktur ist in 10–18% der Fälle durch primäre Radialisparese kompliziert. Sekundäre Radialisläsionen treten iatrogen bei intramedullären Verfahren in 3%, bei Plattenosteosynthesen in 15,5% auf. In der überwiegenden Mehrzahl der Fälle (80%) ist der Radialisschaden rückläufig. Eine Verletzung der A. radialis ist eher selten; sie erfordert ein offenes Vorgehen mit lokaler Revision des Gefäßes und Frakturversorgung mittels Plattenosteosynthese. Die Marknagelosteosynthese ist bei einfachen, komplexen oder pathologischen Schaftfrakturen primär oder als Verfahrenswechsel nach primärer Fixateuranlage indiziert. Während auch ausgewählte Frakturen im Collum chirurgicum mit einem Nagel versorgt werden können, sind Frakturen im distalen Viertel des Humerus ausgeschlossen. Frakturen bei kleinen Kopffragmenten weisen ein erhöhtes Komplikationsrisiko auf. Zur Vermeidung von Läsionen der Rotatorenmanschette stehen wir der anterograden Nagelung noch zurückhaltend gegenüber. Bei differenzierter Indikationsstellung und Nachbehandlung erwies sich die retrograde Marknagelung als ein schonendes Verfahren mit hohem Patientenkomfort und gutem funktionellem Ergebnis.  相似文献   
39.
AIMS: This study evaluates feasibility, safety, and efficacy of magnetic remote-controlled accessory pathway (AP) ablation. METHODS AND RESULTS: The novel magnetic navigation system (MNS) (Niobe, Stereotaxis) creates a steerable magnetic field (0.08 T) controlling the distal magnetic tip of an ablation catheter. In conjunction with a catheter advancer system (Cardiodrive, Stereotaxis) remote catheter ablation is enabled. Conventional electrophysiology study identified AP conduction in 59 patients (37 males, 36+/-14 years, 60 APs). First generation 1-magnet tip (1-M) (group I, n=18), second generation bipolar 3-magnet tip (3-M) (group II, n=27), and third generation quadripolar 3-magnet tip catheters (3-M quad.) (group III, n=14) were used for magnetic remote-controlled ablation. Successful AP ablation was achieved in 67% (group I), 85% (group II), and 92% (group III). A significant decrease of median [IQR: Q1-Q3] fluoroscopy time and dosage was observed: 21.2 [12.1-33.8] min, 1110 [395-3234] microGym2 (group I); 6.5 [4.4-15.4] min, 290 [129-489] microGym2 (group II), and 4.9 [3.4-8.0] min, 129 [74-270] microGym2 (group III). Mean procedure time (217+/-67 min; 182+/-68 min, and 172+/-90 min) significantly decreased in group III. Median number [Q1-Q3] of radiofrequency current applications in groups I, II, and III was 4 [2-9], 4 [2-6], and 2 [2-4], respectively. No complications occurred. CONCLUSION: Remote AP ablation is safe and feasible using the novel MNS. Introduction of the 3-magnet quadripolar ablation catheter significantly improved the efficacy of the procedure.  相似文献   
40.
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