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   1075048篇
  免费   71574篇
  国内免费   1366篇
耳鼻咽喉   15016篇
儿科学   34613篇
妇产科学   28624篇
基础医学   153403篇
口腔科学   29555篇
临床医学   94924篇
内科学   203644篇
皮肤病学   24409篇
神经病学   81442篇
特种医学   42969篇
外国民族医学   201篇
外科学   163096篇
综合类   21702篇
现状与发展   1篇
一般理论   263篇
预防医学   74608篇
眼科学   24540篇
药学   86124篇
  7篇
中国医学   2805篇
肿瘤学   66042篇
  2019年   7759篇
  2018年   11296篇
  2017年   8907篇
  2016年   10094篇
  2015年   11262篇
  2014年   15270篇
  2013年   22198篇
  2012年   30545篇
  2011年   32288篇
  2010年   18953篇
  2009年   17813篇
  2008年   29952篇
  2007年   32068篇
  2006年   32701篇
  2005年   31035篇
  2004年   29727篇
  2003年   28557篇
  2002年   27528篇
  2001年   60027篇
  2000年   61479篇
  1999年   50929篇
  1998年   12448篇
  1997年   11003篇
  1996年   11014篇
  1995年   10322篇
  1994年   9342篇
  1993年   8857篇
  1992年   37794篇
  1991年   36273篇
  1990年   35745篇
  1989年   34286篇
  1988年   30866篇
  1987年   29986篇
  1986年   28214篇
  1985年   26449篇
  1984年   19185篇
  1983年   16113篇
  1982年   8822篇
  1979年   17033篇
  1978年   11404篇
  1977年   10229篇
  1976年   8837篇
  1975年   10069篇
  1974年   11652篇
  1973年   11273篇
  1972年   10757篇
  1971年   10095篇
  1970年   9252篇
  1969年   8939篇
  1968年   7919篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
231.
The aim of this study was to investigate retrospectively the efficacy of expandable metallic stents (EMSs) for severe respiratory distress in patients with central airway obstruction. Twenty patients with central airway obstructions were treated with an EMS. An intraluminal stricture was present in 15 and an extraluminal stricture in 5 patients. Of the 15 patients with intraluminal stenosis, 11 exhibited symptomatic improvement. All 11 patients had tumor infiltration occupying less than 50% of the endoluminal diameter. The other four patients with intraluminal stenosis had tumor infiltration occupying > 50% of the endoluminal diameter and demonstrated no improvement. All five patients with extraluminal stenosis were improved. EMS is useful for an extraluminal stricture in the central airway and the effect of EMS for intraluminal stenosis is related to the degree of infiltration and of tumor progression itself.   相似文献   
232.
The biodistribution of two recently developed tumour markers, trimethylated (CP(Me)3) and trimethoxylated (CP(OMe)3) carotenoporphyrin, was investigated by means of laser-induced fluorescence (LIF) after i.v. injection into 38 tumour-bearing (MS-2 fibrosarcoma) female Balb/c mice. At 3, 24, 48 or 96 h after administration, the carotenoporphyrin fluorescence was measured in tumoral and peritumoral tissue, as well as in the abdominal, thoracic and cranial cavities. The fluorescence was induced by a nitrogen laser-pumped dye laser, emitting light at 425 nm, and analysed by a polychromator equipped with an image-intensified CCD camera. The fluorescence was evaluated at 490, 655 and 720 nm: the second and third wavelengths represent the carotenoporphyrin (CP)-related peaks, whereas the first one is close to the peak of the tissue autofluorescence. The tumour and the liver were the two tissue types showing the strongest carotenoporphyrin-related fluorescence, whereas the cerebral cortex and muscle consistently exhibited weak substance-related fluorescence. In most tissue types, the fluorescence intensities decreased over time. A few exceptions were observed, notably the liver, in which the intensity remained remarkably constant over the time period investigated.  相似文献   
233.
Zusammenfassung Zahlen zur H?ufigkeit von Herztumoren im operativen Krankengut liegen bisher für die Bundesrepublik Deutschland nicht vor. Um einen entsprechenden überblick für das Jahr 1996 zu erhalten, wurde allen 77 herzchirurgischen Zentren der Bundesrepublik Deutschland ein standardisierter Fragebogen zugesandt. Daten von 65 der 77 Herzzentren (=84%) waren schlie?lich verfügbar: 187 Patienten waren wegen Myxomen, lediglich 44 wegen nichtmyxomat?sen Tumoren, davon 28 wegen malignen prim?ren oder sekund?ren Herztumoren, operiert worden. Im Jahr 1996 waren somit 0,32% (231/72 763) der Eingriffe mit Herz-Lungen-Maschine (erfa?t 72 763 von insgesamt 87 372) wegen eines Herztumors vorgenommen worden. Ausgehend von diesen operativen Daten liegt die Inzidenz ausschlie?lich der prim?ren Tumoren des Herzens zumindest bei 3 Tumoren pro 1 Million Einwohner pro Jahr (253 Tumoren/81,814 Millionen Einwohner). Wenn auch kleine Tumoren asymptomatisch und unentdeckt bleiben k?nnen, wird heute doch die Mehrzahl prim?rer kardialer Tumoren durch Echokardiographie, Computer- und Kernspintomographie bereits zu Lebzeiten des Patienten diagnostiziert, und diese Patienten werden in aller Regel einer Operation zugeführt. Somit werden gut 0,3% aller Eingriffe mit Herz-Lungen-Maschine in Deutschland wegen Herztumoren durchgeführt, wobei es sich weit überwiegend um Myxome handelt. Eingegangen: 23. September 1997, Akzeptiert: 11. Februar 1998  相似文献   
234.
Recurrent dislocation of the patella and the Goldthwait operation   总被引:1,自引:0,他引:1  
In this study 17 patients with recurrent dislocation of the patella were followed up 10 years after their Goldthwait operation. The subjective and clinical findings were excellent or good in 70%. X-radiographs indicated osteoarthritis of the femoropatellar joint in 60%. Concerning the aetiopathological factors, we found an increased external torsion of the afflicted extremity (measured by computed tomography).  相似文献   
235.
Bone mineral density in patients with atopic dermatitis   总被引:1,自引:0,他引:1  
With the aim of evaluating the systemic effect of glucocorticoids (GCs), we measured bone mineral density (BMD) in 29 adult patients with chronic atopic dermatitis. BMD was measured in the lumbar spine and in the left femoral neck using dual–energy X–ray absorptiometry (DEXA). In the right calcaneus. BMD was measured using broad–spectrum ultrasound attenuation (BUA). For BMD, the patients with dermatitis did not differ from healthy controls. We did not find any statistically significant correlation between BMD and single risk factors, such as the barrier function of the skin (P = 0.08), the duration of the dermatitis (P = 0.58), and the use of oral GCs (P = 0.27) and potent topical GCs (P = 0.10). However, selected patients with severe disease, needing topical GCs of higher potency than hydrocortisone (HC), had lower values for lumbar BMD than the patients who had not used these preparations (–1.0 vs. +0.1 SD; P = 0.026). The lower lumbar BMD in this group could be explained by a long-term systemic effect of GCs.  相似文献   
236.
Abstract Perioscan requires a plaque sample to detect the presence of enzymes capable of degrading N-benzoyl-DL-arginine-2-naphthylamide (BANA) from relatively few anaerobic periodontal pathogens. Periocheck assays the presence of neutral proteases in crevicular fluid. The aim of this study was to compare these test kits with traditional clinical methods of detecting periodontal disease and to monitor the ability of the kits to reflect the response to initial therapy. 19 patients with moderately severe chronic periodontitis were seen before and after a course of oral hygiene and root instrumentation consisting of 4 appointments. Clinical measurements and test assays were collected at 5 diseased sites and 2 healthy sites in each subject. Complete data from 125 sites were available for statistical analysis. At baseline Periocheck had a sensitivity of 88% and a specificity of 61% whereas Perioscan had a sensitivity of 99% and a specificity of 55%, when related to the clinical diagnosis. A composite clinical assessment, based on improvement or deterioration of one whole unit change of the subjective clinical indices and 2mm changes or greater in probing depth or probing attachment level, revealed 75 sites which improved following treatment, whereas 45 sites did not change and 5 sites deteriorated. The probability that the tests agreed with the clinical outcome after treatment, was calculated as 50.4% for Periocheck and 52% for Perioscan. The diagnostic kits did not reliably reflect the clinical assessment of periodontal disease in the cross sectional study, or the outcome following treatment.  相似文献   
237.
In order to satisfy the need to restore the aesthetics, phonetics and comfort and to facilitate optimal hygiene procedures, 20 edentulous patients were treated with a new concept of overdenture therapy on implants ad modum Brånemark. After 24±3.5 months the patients were re‐examined. They were asked to answer a questionnaire and use a Visual Analogue Scale (VAS) to give their opinion on the prosthetic treatment. The results indicate that an implant‐retained overdenture in the maxilla with this design can satisfy the patients needs in aesthetics, phonetics and comfort and can 1 facilitate oral hygiene measures.  相似文献   
238.
The carpal regions of ten cadaver extremities were imaged by CT. The images were combined into a 3-dimensional model of the carpus using a technique based on a dynamic programming algorithm to find an optimal estimate of the location of the bone boundaries in the CT images. The resulting set of surface points on each bone was used to compute volumes and principal and antipodal axes for the bones. A spatial coordinate system was established based on the positions of the centroids of three bones in the distal carpal row. The angular orientations of all carpal bones were determined with respect to this system. The principal axes for the same bone among ten wrist specimens proved to be more widely dispersed than the antipodal axes for the same bones. The antipodal axes also correspond more closely to an intuitive notion of the “longest axis” of the bones. We conclude that the antipodal axis is a more reliable and useful measure of bone orientation than the principal axis.  相似文献   
239.
240.
Three patients who experienced premature complete physeal closure of the ipsilateral limb following diaphyseal fractures are reported. The diagnosis was recognized because of unexpected progressive limb length discrepancy following fracture healing. The cause is unknown. This phenomenon should be recognized by those treating fractures in children.  相似文献   
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