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   846篇
  免费   42篇
  国内免费   14篇
耳鼻咽喉   6篇
儿科学   9篇
妇产科学   4篇
基础医学   73篇
口腔科学   5篇
临床医学   49篇
内科学   168篇
皮肤病学   16篇
神经病学   201篇
特种医学   64篇
外科学   237篇
综合类   4篇
预防医学   14篇
眼科学   4篇
药学   39篇
肿瘤学   9篇
  2020年   7篇
  2017年   9篇
  2016年   7篇
  2015年   9篇
  2014年   15篇
  2013年   12篇
  2012年   22篇
  2011年   12篇
  2010年   8篇
  2009年   17篇
  2008年   15篇
  2007年   22篇
  2006年   14篇
  2005年   22篇
  2004年   19篇
  2003年   25篇
  2002年   27篇
  2001年   33篇
  2000年   37篇
  1999年   42篇
  1998年   26篇
  1997年   23篇
  1996年   25篇
  1995年   19篇
  1994年   28篇
  1993年   15篇
  1992年   26篇
  1991年   18篇
  1990年   27篇
  1989年   20篇
  1988年   20篇
  1987年   18篇
  1986年   24篇
  1985年   17篇
  1984年   8篇
  1982年   8篇
  1981年   8篇
  1980年   13篇
  1979年   10篇
  1978年   8篇
  1977年   8篇
  1976年   8篇
  1975年   8篇
  1974年   15篇
  1973年   7篇
  1972年   7篇
  1971年   13篇
  1970年   13篇
  1969年   9篇
  1968年   11篇
排序方式: 共有902条查询结果,搜索用时 0 毫秒
51.
52.
BACKGROUND: Untreated, one third of patients who undergo surgery will have postoperative nausea and vomiting. Although many trials have been conducted, the relative benefits of prophylactic antiemetic interventions given alone or in combination remain unknown.METHODS: In a randomized, controlled trial of factorial design, 5,199 patients at high risk for postoperative nausea and vomiting were randomly assigned to 1 of 64 possible combinations of 6 prophylactic interventions: 1) 4 mg of ondansetron or no ondansetron; 2) 4 mg of dexamethasone or no dexamethasone; 3) 1.25 mg of droperidol or no droperidol; 4) propofol or a volatile anesthetic; 5) nitrogen or nitrous oxide; 6) remifentanil or fentanyl. The primary aim parameter was nausea and vomiting within 24 h after surgery, which was evaluated blindly.RESULTS: Ondansetron, dexamethasone, and droperidol each reduced the risk of postoperative nausea and vomiting by about 26%, propofol reduced the risk by 19%, and nitrogen by 12%. The risk reduction with both of these agents (i.e., total intravenous anesthesia) was thus similar to that observed with each of the antiemetics alone. All the interventions acted independently of each other and independently of the patients' baseline risk. Consequently, the relative risks associated with the combined interventions could be estimated by multiplying the relative risks associated with each intervention. However, absolute risk reduction was a critical function of patients' baseline risk.CONCLUSIONS: Because antiemetic interventions are similarly effective and act independently, the safest or least expensive should be used first. Prophylaxis is rarely warranted in low-risk patients, moderate-risk patients may benefit from a single intervention, and multiple interventions should be reserved for high-risk patients.  相似文献   
53.
Zusammenfassung Anwendungsweise und Anzeigestellung für den Gebrauch der Kopfklammer nach Crutchfield bei Halswirbelverletzungen werden an Hand von Beispielen beschrieben. Gegenüber dem Dauerzug mittels der Glissonschlinge hat die Crutchfield-Klammer den Vorteil einer weit besseren Verträglichkeit und Ruhigstellung, sowie Essenserleichterung. Ja nach der Höhe der vorliegenden Verletzung werden verschieden große Zuggewichte benötigt. Die Sicherung des erzielten Korrekturergebnisses erfolgt in der Regel durch nachfolgenden Schanzschen Watteverband, wobei ältere Personen zur späteren Wiederkehr der Wirbelverschiebung infolge schlechterer Regenerationsbedingungen neigen. Weitere Anwendungsbereiche der Crutchfield-Klammer sind zerstörende Prozesse im Bereiche der Halswirbelsäule, die eine Dauerzugbehandlung über Monate erfordern und schwere Skoliosen mit Lähmungserscheinungen zur Dauerzugsvorbereitung für die Laminektomie.Wegen der einfachen Technik der Anwendung und der Zuverlässigkeit ist die Crutchfield-Klammer der weit weniger leistungsfähigen Glissonschlingenextension vorzuziehen.Mit 16 Textabbildungen (32 Einzelbilder).  相似文献   
54.
55.
Summary This report deals with two patients, brother and sister, suffering from spastic paraplegia. Onset of the disease was at 46 and 51 years of age, respectively. The outstanding clinical features were a slowly progressive course of the disease and an overall slight to moderate impairment of motility in spite of the long duration of the disease of more than 8 to 10 years. The family history failed to reveal any other affected members and we therefore concluded that the disease was inherited by recessive mode. Our cases belong to the adult form of spastic paraplegia of Strümpell and Haldane. We agree on Becker's suggestion stating that this adult form represents a genetically independent type.  相似文献   
56.
Cortical area MT/V5 in the human occipito-temporal cortex is activated by visual motion. In this study, we use functional imaging to demonstrate that a subregion of MT/V5 is more strongly activated by unidirectional motion with speed gradients than by other motion patterns. Our results suggest that like the monkey homolog middle temporal area (MT), human MT/V5 contains neurons selective for the processing of speed gradients. Such neurons may constitute an intermediate stage of processing between neurons selective for the average speed of unidirectional motion and neurons selective for different combinations of speed gradient and different motion directions such as expanding optical flow patterns.  相似文献   
57.
In 1928, Hugo Friedrich Kufs reported on a family with cerebral, retinal, and cutaneous cavernous malformations. Since then, more than 300 families with inherited cavernous malformations have been reported. Genetic studies showed three loci, on chromosomes 7q21-q22 (with the gene CCM1), 7p15-p13 (CCM2), and 3q25.2-q27 (CCM3). The gene product of CCM1 is Krit 1 (Krev interaction trapped 1), a protein interacting with angiogenesis by various mechanisms. Recently, CCM2 has also been identified; its product is a protein which might have a function similar to that of Krit 1. However, the CCM3 gene has still not been found. In this study, we present clinical and genetic findings on 15 German families.  相似文献   
58.
AIM: Low-intensity pulsed ultrasound has been proven to accelerate fracture healing both clinically and experimentally. In this study the influence of low-intensity pulsed ultrasound during distraction-osteogenesis in case of delayed callotasis was investigated. METHOD: 20 patients could be included in this study. 16 patients initially were treated because of fractures of the lower leg, 2 because of fractures of the femur with resulting shortening of the afflicted limb. One patient suffered from chronic osteitis at the thigh and one from chronic osteitis at the upper arm without previous trauma. Because of delayed callotasis an adjunctive ultrasound treatment device was transcutaneously applied (frequency 1.5 MHz, signal burst width 200 microseconds, signal repetition frequency 1.0 kHz, intensity 30 mW/cm (2)) with the transducer placed at the distraction zone for 20 minutes daily. In all cases in-home treatment was performed. Evaluation was done by radiographic and sonographic controls of the distraction zone during examination of all patients at the outpatients' department every 3-4 weeks. RESULTS: Progress of callotasis was achieved in 15 out of 20 patients. Patients who were smokers during ultrasound therapy showed lower healing rates than those who never smoked. 2 patients suffering from osteitis of the tibia and missing callotasis had to be amputated. 3 other patients needed additional operative treatment including cancellous bone grafts because of missing new bone formation. Negative effects of low-intensity pulsed ultrasound during therapy could not be detected. CONCLUSION: We conclude that ultrasound treatment can accelerate bone maturation and formation in distraction osteogenesis, sometimes even in states of poor callotasis. It may provide a method of great promise in cases where delayed bone formation during distraction osteogenesis occurs.  相似文献   
59.
Indication, biomechanics and early results of artificial disk replacement   总被引:4,自引:0,他引:4  
AIM: Judgment of factors concerning the indication for the implantation of an artificial disc endoprosthesis, the rating of this operation and biomechanical considerations. METHOD: Presentation of the indication and the value of a new operative concept in comparison to a so-called dynamic stabilization procedure (Dynesys' method). Indications for the operation are: unsuccessful, orthopedic conservative treatment for > 6 months, segmental pain, age < 45 years, evidence of an MRI demonstrable mono- or bisegmental disc degeneration with or without disc prolabation, exclusion of psychogenic disease and positive preoperative, diagnostic measures such as facet joint infiltration and discography. RESULTS: In an earlier investigation the efficacy of the Link method was demonstrated as shown by the reduction of the analgesic use, the angle of the lumbar lordosis (L1-S1) increased from 35.6 degrees to 42.6 degrees (20.2 %), the segmental angle from 19 degrees to 30 degrees (57.5 %). The new investigation using the Aesculap endoprosthesis resulted in a change of the angle of lumbar lordosis from 35.4 degrees to 45.4 degrees (25.4 %) and a change of the segmental angle from 17.3 degrees to 29.1 degrees (57.6 %). This method is a real endoprosthetic instrumentation in the field of spinal surgery. CONCLUSION: In younger patients with mono- or bisegmental disc degeneration there is an indication for the implantation of a disc endoprosthesis. A facet joint arthrosis and an age over 45 years are contraindications for the operation. The indication in patients with a classic failed back surgery syndrome is still unclear, the improvement of the instrumentation and a further adaptation of the systems to the known biomechanics of the lumbar spine are mandatory as is an intensive discussion of the operative procedure in the case of revision operations. The Dynesys method, with the inherent danger of segmental kyphozitation, a published, significant revision quota combined with a reduction of motility, does not fulfill this criterion.  相似文献   
60.
The (dis-)advantages of preoperative chemoradiation in patients with esophageal cancer (EC) are still controversial as data are lacking showing a clear cut benefit. Therefore, data of neoadjuvant therapy of our hospital have been analyzed.Since 1994 102 patients with an EC (33 % adenocarcinoma, 67 % squamous cell cancer, scc) were operated after receiving preoperative chemoradiation (36 Gy radiation, 1.8 Gy/day for 4 weeks, 500 mg/m (2) 5-FU for 4 weeks and 20 mg/m (2) Cisplatin, day 1-5, week 1 and 4). Operation was performed usually 8-10 weeks after treatment start.In 11.7 % of patients with an adenocarcinoma a complete pathological response (CR, pT0N0M0) was observed and a pT0 stage in 20.6 %. 38.2 % of these patients were staged as pN0. Postoperative morbidity was observed in 66 % (anastomotic leakage in 20 %, recurrent nerve palsy in 23 %). In-hospital mortality was 5.9 %. 5-year survival was calculated as 30.5 %, in patients wit a CR 66 %.26.5 % of patients with a scc revealed a CR. However no effect at all was observed in 32 % of these patients. 56 % were staged as pN0. Postoperative morbidity was observed in 87 % (anastomotic leakage in 16 %, recurrent nerve palsy in 32 %). In-hospital mortality was 11.8 %. 5-year survival was calculated as 19.2 %, in patients with a CR 45 %. The impact of pN stage was significant (p = 0.0052).These results underline the benefit of neoadjuvant therapy in patients with a CR. Further on, a pN0 stage is an important prognostic indicator. However, it remains open, whether neoadjuvant therapy leads to a downstaging of lymph node involvement, as histological confirmation in clinically positive lymph node is seldom performed prospectively.  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