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   58608篇
  免费   3435篇
  国内免费   41篇
耳鼻咽喉   938篇
儿科学   1776篇
妇产科学   1368篇
基础医学   8691篇
口腔科学   2220篇
临床医学   5466篇
内科学   10506篇
皮肤病学   1448篇
神经病学   6264篇
特种医学   2713篇
外科学   8206篇
综合类   204篇
一般理论   32篇
预防医学   3834篇
眼科学   1188篇
药学   4069篇
中国医学   87篇
肿瘤学   3074篇
  2023年   324篇
  2022年   220篇
  2021年   492篇
  2020年   577篇
  2019年   621篇
  2018年   1308篇
  2017年   1113篇
  2016年   1451篇
  2015年   1156篇
  2014年   1336篇
  2013年   2475篇
  2012年   3120篇
  2011年   3547篇
  2010年   1862篇
  2009年   1176篇
  2008年   3540篇
  2007年   3692篇
  2006年   3475篇
  2005年   3385篇
  2004年   3249篇
  2003年   3296篇
  2002年   3224篇
  2001年   2550篇
  2000年   3272篇
  1999年   1726篇
  1998年   557篇
  1997年   487篇
  1996年   353篇
  1995年   296篇
  1994年   318篇
  1993年   301篇
  1992年   286篇
  1991年   230篇
  1990年   218篇
  1989年   283篇
  1988年   214篇
  1987年   217篇
  1986年   221篇
  1985年   287篇
  1984年   309篇
  1983年   264篇
  1982年   266篇
  1981年   215篇
  1980年   208篇
  1979年   232篇
  1978年   181篇
  1977年   193篇
  1976年   188篇
  1975年   163篇
  1973年   174篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
83.
Summary In the last decades back pain has reached dramatic proportions in industrialized countries. Disorders of the back are nowadays the leading cause of direct and indirect health care costs. Accurate prevalence estimates are needed to serve as a basis for health care evaluations. A review of epidemiologic studies in the general population reveals that back pain has reached a prevalence of 40 % for current pain. 7 to 18 % are “frequently”, “often”, “daily” or “constantly” affected. 75 % of the adult population suffers from back pain during the last year. 80 to 90 % of the adult population in industrialized countries experience back pain ever. Gender specific differences are only present in severe, chronic forms which are more often experienced by women. Back pain has a prevalence maximum at 50 to 64 years. Older persons display lower prevalence estimates. The prevalence maximum in men is one decade earlier than in women. There are several potential explanations for this prevalence pattern that are discussed in the article. Back pain can be classified by location, temporal characteristics, pain intensity and pain history. Currently, for none of these dimensions generally accepted, uniformly employed and validated definitions are available. In most of the industrialized countries back pain is one of the most expensive symptoms. 75–90 % of the direct and indirect health care costs were caused by those 5–10 % of patients who are disabled. As predictors of back pain a history of back pain and job satisfaction play by far a more important role than the extensively studied mechanical factors. For a first episode of back pain the prognosis is favorable. If the pain persist for more than three months the prognosis is unfavorable. After six months of absenteeism because of back pain more than half of the afflicted never return to work. Rarely back pain is present as a single symptom. In more than 80 % back pain is associated with pain in at least one joint. It remains to be studied if back pain may be viewed as an entity or as part of a more complex pain syndrome.   相似文献   
84.
From 1980 to 1990 152 patients underwent Fontan operation at our institution. The following patient groups amenable for Fontan operation were identified: 1) patients with tricuspid atresia (n=82, 54.0%); 2) patients with single ventricle (n=31,20.3%), 3) patients with a wide variety of “complex”, non correctable cardiac malformations (n=39, 25.7%). Actuarial survival rate was 83.8±3.1% (mean±SEM) at 10 years. Follow up revealed, that more than 90.0% of the patients feel better than before operation, about 50.0% are without cyanosis, more than 70.0% are in sinus rhythm, and 90.0% of the patients are socialized according to their age. Considering the poor prognosis of these patients without an operation, the Fontan procedure offers a sufficient palliative method in the therapeutic approach up to now.  相似文献   
85.
The aim of this study was to investigate factors associated with life dissatisfaction in symptomatic patients (n = 144) with chest pain subsequently diagnosed as coronary heart disease (CHD) by coronary angiography. Life dissatisfaction was assessed with a four-item life satisfaction scale (LS), depression with the 21-item Beck Depression Inventory (BDI) and other psychiatric symptoms with the symptom check list (SCL). DSM-III-R Axis I and Axis II psychiatric diagnoses were performed by means of the Structured Clinical Interview. All assessments took place one day before angiography. Twenty-four per cent of CHD patients were dissatisfied with their lives. Life dissatisfaction was associated with being unmarried. Dissatisfied patients had Axis I mental disorders and Axis II personality disorders more frequently than others. Psychiatric and depressive symptoms according to the SCL and BDI, respectively, were also higher among dissatisfied patients. In multiple logistic regression analyses, mental disorders were related to life dissatisfaction when age, sex, employment status, New York Heart Association class, duration of chest pain symptoms and work load were controlled in the model. Married subjects had a lower probability of being dissatisfied with their lives than other subjects (Odds Ratio, OR: 0.23). When BDI scores were included in the model, the only factor independently associated with life dissatisfaction was the severity of depressive symptoms (OR: 1.81). To conclude, life dissatisfaction is not primarily determined by the severity of CHD but by the existence of depressive symptoms.  相似文献   
86.
Osteotomies of the distal femur were fixed with two self-reinforced poly-L-lactic acid (SR-PLLA) plates and metallic screws placed through the plates on each side of the femur in 23 adult rabbits. They were followed-up after 3, 6, 12 and 24 weeks. After killing, radiological, histological, microradiographic and oxytetracycline fluorescence studies were performed. Except for one histologically confirmed fibrotic non-union at 24 weeks, the osteotomies healed, including one involving a rabbit which had suffered an ipsilateral femoral shaft fracture of unknown cause. No malformations were observed, and the macroscopically detected swelling was a normal postoperative reaction. This study showed that SR-PLLA plates implanted on both sides on the bone are suitable for the fixation of weight-bearing cancellous bone osteotomies in rabbits.  相似文献   
87.
Objective: To determine whether the quality of infiltrations in chest radiographs can accurately predict the histological extent of fibrotic change in patients with acute respiratory distress syndrome (ARDS). Design: Retrospective clinical investigation. Setting: Intensive care unit (ICU) of a university teaching hospital. Patients and methods: Of 47 patients treated with extracorporeal membrane oxygenation (ECMO) for severe ARDS over a 5-year period, 23 patients underwent open lung biopsy at thoracotomy for treatment, mostly of pneumothorax. Chest films obtained by portable chest roentgenography preceding the operation were reviewed retrospectively and compared to the histomorphological results of the lung specimen. Results: Chest radiographs displayed mixed alveolar-reticular opacification in 60.2 %, alveolar patterns in 22.9 % and reticular opacities in 10.5 %. In 0.4 % there were no infiltrates, 6 % could not be evaluated because of insufficient quality. There was no relevant difference between the right and left lungs. Subdividing patients into two groups according to the histological results of either absent or mild (1) or severe (2) lung fibrosis, we found an alveolar haziness in 12.3 % in group 1 compared with 28.2 % in group 2, while reticular characteristics were identified in 13 % and 11 %, respectively. Conclusions: The most common opacity in chest radiographs of patients with severe ARDS treated with ECMO is mixed alveolar-reticular opacification. Severe lung fibrosis is not positively correlated with a reticular radiographic pattern. ECMO does not lead to specific radiological changes in conventional radiograms, contrary to clinical findings that treatment with ECMO might induce pleural or pulmonic haemorrhage, especially in the earlier days when systemic heparinization had to be used instead of the heparin-coated tube-surfacing. Received: 24 November 1997 Accepted: 20 July 1998  相似文献   
88.
Schlu?folgerungen Unser Motto in der Chirurgie sollte hei?en: „An erster Stelle steht die Qualit?t, erst sekund?r kommen die Kosten.“ In diesem Sinne verstehen wir auch die vorgelegte Arbeit vonKriwanek et al. (1). Durch den Gebrauch von wiederverwendbaren Instrumenten (oder Kombinationen davon) konnten die Kosten der LC um 50 bis 70% reduziert werden. Die Qualit?t für den Chirurgen litt jedoch unter dem reinen Gebrauch von wiederverwendbaren Instrumenten. Deshalb erachten es die Autoren für sinnvoll, eine Kombination zwischen Wegwerfinstrumenten und wiederverwendbaren Instrumenten anzuwenden. Damit entsteht unter leichter Erh?hung der Kosten keine Qualit?tseinbu?e und demzufolge ein maximaler Nutzen für die Patienten (nicht jedoch für die Spital?konomen). Jede Kosten-Nutzen-Analyse unterliegt jedoch einem stetigen Flu? und ver?ndert sich demzufolge auch mit der Einführung neuer Produkte und Technologien von Seite der Industrie. Interessant für die gesamte Laparoskopie wird es jedoch dann, wenn solche Kosten-Nutzen-Analysen auf andere Gebiete wie z. B. die Therapie der Leistenhernie oder der Gallengangssteine übertragen werden. Diese Ergebnisse werden die weitere Zukunft der laparoskopischen Chirurgie wesentlich beeinflussen. Deshalb gilt es für uns Chirurgen, eine Sensibilit?t für ?konomische Aspekte zu entwickeln und Kosten-Nutzen-Analysen für das eigene Spital (wie hier gezeigt) zu erarbeiten.  相似文献   
89.
Objective: To quantify gadolinium-related enhancement in the bone marrow of the spine in normals and in patients with homogeneous diffuse malignant bone marrow infiltration. Design and patients: The patients consisted of two groups: group 1 comprised 94 healthy adults (18–86 years) without bone marrow disease and group 2 comprised 30 patients with homogeneous diffuse malignant bone marrow infiltration due to myeloma (n=20) or breast carcinoma (n=10). All patients received intravenous gadopentetate dimeglumine (Gd-DTPA), 0.1 mmol/kg body weight. Pre- and postcontrast signal intensity (SI) on T1-weighted spin-echo (SE) images (TR/TE: 572 ms/15 ms) was measured over a region of interest (ROI) and the percentage SI increase was calculated. The results were confirmed by bone marrow biopsy (n=20) and clinical parameters (n=10). Dynamic contrast-enhanced studies using a spoiled gradient-recalled-echo (GRE) sequence (TR/TE/α: 68 ms/6 ms 75°) were performed in 10 controls with normal bone marrow. Results and conclusion: Contrast material enhancement in healthy persons can vary greatly (range 3–59%, mean 21%, SD 11%). With increasing age there is a significant decrease in contrast enhancement (Pearson’s correlation, P<0.01). The percentage SI increase in patients with intermediate-grade (biopsy 20–50 vol%) and high-grade (biopsy >50 vol%) diffuse malignant bone marrow infiltration was significantly higher than in normals (mean 67%, SD 34%, P<0.001). Low-grade (biopsy <20 vol%) diffuse malignant bone marrow infiltration can not be assessed by non-enhanced T1-weighted SE images or Gd-DTPA application. In conclusion, contrast material enhancement in healthy persons can vary greatly and is dependent on age, while intermediate-grade and high-grade diffuse malignant bone marrow infiltration can be objectively assessed with SI measurements.  相似文献   
90.
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