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   23601篇
  免费   1272篇
  国内免费   172篇
耳鼻咽喉   326篇
儿科学   458篇
妇产科学   550篇
基础医学   2830篇
口腔科学   754篇
临床医学   1925篇
内科学   6390篇
皮肤病学   408篇
神经病学   2309篇
特种医学   743篇
外科学   3455篇
综合类   84篇
一般理论   9篇
预防医学   1095篇
眼科学   317篇
药学   1551篇
  1篇
中国医学   42篇
肿瘤学   1798篇
  2024年   19篇
  2023年   159篇
  2022年   345篇
  2021年   667篇
  2020年   384篇
  2019年   554篇
  2018年   640篇
  2017年   478篇
  2016年   569篇
  2015年   606篇
  2014年   924篇
  2013年   1172篇
  2012年   1821篇
  2011年   1805篇
  2010年   1067篇
  2009年   948篇
  2008年   1641篇
  2007年   1571篇
  2006年   1483篇
  2005年   1485篇
  2004年   1385篇
  2003年   1266篇
  2002年   1159篇
  2001年   177篇
  2000年   178篇
  1999年   204篇
  1998年   196篇
  1997年   187篇
  1996年   185篇
  1995年   170篇
  1994年   137篇
  1993年   126篇
  1992年   116篇
  1991年   76篇
  1990年   92篇
  1989年   82篇
  1988年   79篇
  1987年   85篇
  1986年   68篇
  1985年   72篇
  1984年   78篇
  1983年   76篇
  1982年   67篇
  1981年   60篇
  1980年   55篇
  1979年   31篇
  1978年   40篇
  1977年   27篇
  1976年   21篇
  1975年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Hepatitis E (HE) is an important emerging disease in European countries. To analyse the role of equids as potential reservoirs for HE virus (HEV), we determined the prevalence of HEV infection in 861 equines from 464 herds in Spain. HEV RNA in serum was detected in 0.4% (3/692) of horses, 1.2% (1/86) of donkeys and 3.6% (3/83) of mules. Phylogenetic analysis identified the zoonotic genotype 3 as being closely related to viral human and swine strains. In this first report on HEV in equids in Europe, we confirm the susceptibility of horses, donkeys and mules to HEV infection. The low prevalence detected indicates that equids may be considered spillover hosts rather than true reservoirs.  相似文献   
992.
The COVID‐19 pandemic has rapidly evolved and changed our way of life in an unprecedented manner. The emergence of COVID‐19 has impacted transplantation worldwide. The impact has not been just restricted to issues pertaining to donors or recipients, but also health‐care resource utilization as the intensity of cases in certain jurisdictions exceeds available capacity. Here we provide a personal viewpoint representing different jurisdictions from around the world in order to outline the impact of the current COVID‐19 pandemic on organ transplantation. Based on our collective experience, we discuss mitigation strategies such as donor screening, resource planning, and a staged approach to transplant volume considerations as local resource issues demand. We also discuss issues related to transplant‐related research during the pandemic, the role of transplant infectious diseases, and the influence of transplant societies for education and disseminating current information.  相似文献   
993.
The clinical characteristics, management, and outcome of coronavirus disease 2019 (COVID‐19) caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) after solid organ transplant (SOT) remain unknown. We report our preliminary experience with 18 SOT (kidney [44.4%], liver [33.3%], and heart [22.2%]) recipients diagnosed with COVID‐19 by March 23, 2020 at a tertiary‐care center at Madrid. Median age at diagnosis was 71.0 ± 12.8 years, and the median interval since transplantation was 9.3 years. Fever (83.3%) and radiographic abnormalities in form of unilateral or bilateral/multifocal consolidations (72.2%) were the most common presentations. Lopinavir/ritonavir (usually associated with hydroxychloroquine) was used in 50.0% of patients and had to be prematurely discontinued in 2 of them. Other antiviral regimens included hydroxychloroquine monotherapy (27.8%) and interferon‐β (16.7%). As of April 4, the case‐fatality rate was 27.8% (5/18). After a median follow‐up of 18 days from symptom onset, 30.8% (4/13) of survivors developed progressive respiratory failure, 7.7% (1/13) showed stable clinical condition or improvement, and 61.5% (8/13) had been discharged home. C‐reactive protein levels at various points were significantly higher among recipients who experienced unfavorable outcome. In conclusion, this frontline report suggests that SARS‐CoV‐2 infection has a severe course in SOT recipients.  相似文献   
994.
The injection of bulking agents into the urethral submucosa is designed to create artificial urethral cushions that can improve urethral coaptation and hence restore continence. Ideally, a urethral bulking agent should be non-immunogenic and biocompatible, leading to minimal inflammatory and fibrotic response. The authors present a case report of a granulomatous reaction leading to urethral prolapse, 3 months after the transurethral injection of calcium hydroxylapatite. To our knowledge, this is the first granulomatous reaction described after calcium hydroxylapatite injection.  相似文献   
995.
OBJECTIVE: Because laparoscopic cholecystectomy (LC) is widely recognized as a "mild" or "mini-invasive" kind of surgery, in this prospective nonrandomized study, we investigated the effect of intestinal manipulation on intestinal permeability and endotoxemia, in patients undergoing elective cholecystectomy by comparing the laparoscopic with the laparotomic approach. SUMMARY BACKGROUND DATA: The intestine is susceptible to operations at remote locations, and the barrier function is altered during intestinal manipulation, leading to bacterial or endotoxin translocation into the systemic circulation. METHODS: Forty-three patients undergoing elective cholecystectomy were divided into either the laparotomic (n = 22) or laparoscopic (n = 21) approach. Intestinal permeability was measured preoperatively and at day 1 and day 3 after surgery using the lactulose/mannitol absorption test. Serial venous blood samples were taken at 0, 30, 60, 90, 120, and 180 minutes, and at 12, 24, and 48 hours after surgery, for endotoxin measurement using the chromogenic limulus amoebocyte lysate assay. RESULTS: Intestinal permeability was significantly increased at day 1 [0.106 +/- 0.005 (mean +/- SEM)] in the laparotomic group compared with the preoperative level (0.019 +/- 0.005, P < 0.05) and to the laparoscopic group at day 1 (0.019 +/- 0.005, P < 0.05), which showed no change in comparison with the preoperative level. A significantly higher concentration of systemic endotoxin was detected intraoperatively in the laparotomic group of patients in comparison to the laparoscopic group (P < 0.05). There was a significant positive correlation between systemic endotoxemia and intestinal permeability (r(s) = 0.958; P = 0.001). CONCLUSIONS: An increase in intestinal permeability and a greater degree of systemic endotoxemia are observed during laparotomic cholecystectomy. This suggests that intestinal manipulation may impair gut mucosal barrier function and contribute to the systemic inflammatory response see in open cholecystectomy.  相似文献   
996.
PURPOSE: To present a simple alternative technique to close the membranous urethra during laparoscopic radical cystectomy. PATIENTS AND METHODS: A series of 18 laparoscopy-assisted cystectomies were performed in our institute from November 2002 to May 2005. In order to prevent neoplastic-cell spillage, in 14 of these patients, the membranous urethra was closed with Hem-o-lok clips after careful dissection of the urethra and withdrawal of the bladder catheter. RESULTS: In all cases, one or two Hem-o-lok clips were easily, safely, and quickly positioned. The remaining length of the membranous urethra was sufficient for anastomosis with the neobladder if appropriate. In follow-up (mean 14 months), no local recurrence has been recorded. CONCLUSION: The closing of the membranous urethra with Hem-o-lok clips during laparoscopy-assisted cystectomy is in our experience a simple, fast, safe, and effective alternative that should be considered when laparoscopic radical cystectomy is performed.  相似文献   
997.
998.
In this study we investigated central and peripheral feature binding in a group of 24 high pre-morbid IQ patients with schizophrenia and 24 healthy controls. In particular, participants were asked to remember specific single (e.g., word, colour) or multiple features (e.g., coloured words) of experimental items with central (coloured word) vs. peripheral (a coloured frame) attributes in a working memory binding task. Performance of the patients was significantly inferior to that of controls, especially when required to remember the peripheral combination of multiple features. Results suggest that patients with schizophrenia may have difficulties in unitizing peripheral features in working memory.  相似文献   
999.
Essential tremor (ET) encompasses a group of progressive neurological diseases in which the primary clinical feature is kinetic tremor of the arms. There is accumulating evidence to suggest that the cerebellum is involved in the pathogenesis of ET; the clinical presentation, neurophysiological data, and functional and metabolic abnormalities revealed by neuroimaging studies all point toward the dysregulation of cerebellar circuits. Recent neuropathological findings at postmortem demonstrate that Purkinje neurons, and some brainstem neurons, play an integral role in the pathogenesis of this common neurological disorder. The assessment of Purkinje cell linear density shows that Purkinje density is abnormal in ET brains. Specific efforts need be devoted to understanding the molecular and cellular events occurring in the Purkinje neurons of the cerebellar cortex, which are emerging as being of particular importance in the pathogenesis of ET in a subgroup of patients. © 2013 International Parkinson and Movement Disorder Society.  相似文献   
1000.
PURPOSE: Anterior cruciate ligament (ACL) reconstructive surgery has seen significant progress since bioabsorbable interference screws have replaced synthetic metallic screws for ligament graft fixation within the femoral and tibial osseous tunnel. Our study compared the MR images of patients who underwent ACL reconstruction using bioabsorbable interference screws with those of patients who underwent ACL reconstruction using metallic screws to evaluate the MR aspects of degradation and osteointegration processes of bioabsorbable interference screws post-operatively. MATERIALS AND METHODS: Between September 1999 and December 2002 we performed MRI on 40 patients who underwent arthroscopic ACL reconstruction with patellar tendon auto-graft using PDLLA bioabsorbable screws in 35 cases and metallic screws in 5 cases. After surgery, all patients underwent an intensive rehabilitation programme along with clinical evaluation using the standard knee ligament evaluation form of the International Knee Documentation Committee (IKDC) and radiological examinations. MR studies were performed 1, 2 and 3 years post-operatively using a 0.5-Tesla MR scanner with T1- and T2*-weighted and STIR sequences. RESULTS: Thirty-three patients were clinically classified as group A IKDC (full return to sports activity) and 7 patients as group B IKDC. No foreign-body reaction was found in patients treated with bioabsorbable interference screws, both from a clinical point of view and from laboratory exams. Ferromagnetic artefacts were found in all patients treated with metallic interference screws. In patients with bioabsorbable interference screws, degradation of the screws and absence of significant artefacts allowed correct evaluation of the signal of the reconstructed ligament throughout its length, the osseous tunnels and the joint cavity. In 34 of 35 patients with bioabsorbable interference screws, the screw could not be detected due to complete degradation. In 8, 12 and 4 cases, a small cyst-like formation due to screw hydrolysis was present at the screw site within 1, 2 and 3 years from surgery respectively. Only in 4 cases was the process of osteointegration of the screw and bone plug complete 3 years after the operation, with consequent restoration of bone morphology. DISCUSSION AND CONCLUSIONS: The use of bioabsorbable interference screws is a valuable alternative to synthetic metallic fixation implants as the absence of artefacts allows correct post-operative MR follow-up. MRI is the only technique able to visualize all the portions of the transplant and to evaluate the healing process. Bioabsorbable interference screws usually degrade within one year. However, full osteointegration requires a long time and may not be complete 3 years after surgery. The presence of cyst-like formations at the screw site has to be regarded as a normal feature of the screw degradation process. Therefore, the use of bioabsorbable interference screws is recommended as it enables MR follow-up of the knee after ACL reconstruction.  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