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   10218篇
  免费   654篇
  国内免费   48篇
耳鼻咽喉   126篇
儿科学   263篇
妇产科学   267篇
基础医学   1465篇
口腔科学   221篇
临床医学   1014篇
内科学   2301篇
皮肤病学   194篇
神经病学   1403篇
特种医学   280篇
外科学   993篇
综合类   27篇
一般理论   5篇
预防医学   743篇
眼科学   159篇
药学   662篇
中国医学   41篇
肿瘤学   756篇
  2024年   15篇
  2023年   98篇
  2022年   155篇
  2021年   291篇
  2020年   180篇
  2019年   279篇
  2018年   307篇
  2017年   268篇
  2016年   318篇
  2015年   311篇
  2014年   396篇
  2013年   532篇
  2012年   821篇
  2011年   818篇
  2010年   440篇
  2009年   407篇
  2008年   656篇
  2007年   663篇
  2006年   624篇
  2005年   651篇
  2004年   565篇
  2003年   519篇
  2002年   498篇
  2001年   98篇
  2000年   82篇
  1999年   107篇
  1998年   95篇
  1997年   73篇
  1996年   46篇
  1995年   52篇
  1994年   45篇
  1993年   36篇
  1992年   47篇
  1991年   49篇
  1990年   50篇
  1989年   29篇
  1988年   28篇
  1987年   29篇
  1986年   24篇
  1985年   24篇
  1984年   34篇
  1983年   17篇
  1982年   23篇
  1981年   16篇
  1980年   14篇
  1979年   14篇
  1978年   9篇
  1976年   7篇
  1974年   13篇
  1973年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
A core feature of autism is the abnormal use of gaze to attribute mental states to others, and thus to predict others' behaviour. An untested idea is whether this dysfunction is confined to mental states having a propositional content, such as beliefs and desire or extends to motor intentional states which allow one to make inferences about the actions of others. This study used kinematics to examine the ability to use gaze to inform one about the motor states of another in normal and autistic children. In each trial two participants, a model and an observer, were seated facing each other at a table. In three experimental blocks the model was requested to grasp a stimulus, to gaze towards the same stimulus, and to gaze away from the stimulus without performing any action. The task for the observer was to grasp the stimulus after having watched the model perform her task. We observed that normal children showed facilitation effects in terms of movement speed following the observation of the model grasping or simply gazing at the object. In contrast, autistic children did not show any evidence of facilitation in these conditions. Neither normal nor autistic children showed evidence of facilitation when the model's gaze was not directed towards the stimulus. These findings demonstrate that, in contrast to normal children, children with autism fail to use information from the model's action or gaze to plan their subsequent action, and that in autism the inability to use of another person's gaze produces a lack of understanding of the motor intention of others.  相似文献   
82.
OBJECTIVE: This prospective, open-label study was conducted to evaluate the effectiveness, tolerability, and safety of levetiracetam in patients with epilepsy in whom unfavorable metabolism, complex drug interactions, or direct toxic effects of antiepileptic drugs (AEDs) had caused a worsening of comorbid conditions. METHODS: Study design included the introduction of levetiracetam, discontinuation of other AEDs, and a serial assessment comprising electroencephalograms and blood tests at baseline and 2, 6, and 12 months. Of 21 patients, 16 had partial and five generalized epilepsy. Concomitant pathologies were gastroenterological (six), vascular (four), endocrinological (four), or complex conditions including hematological (four) or dermatological (three) disease. A change of regimen was necessitated by drug-drug interactions in four patients, direct real or potential toxic effects of previous AEDs in 13, and a combination of interactions/toxic effects in four. RESULTS: After 12 months, 12 patients were seizure-free, nine had reductions in seizure frequency of 50-75%, and improvement in concomitant medical conditions was observed. No side effects were reported. CONCLUSION: Levetiracetam appears to be effective, well tolerated, and safe in patients with epilepsy and other medical conditions that are difficult to manage because of drug interactions or AED-related side effects.  相似文献   
83.
Choroid plexus ependymal cells host neural progenitor cells in the rat   总被引:2,自引:0,他引:2  
We previously demonstrated that choroid plexus epithelial (modified ependymal) cells (CPECs) differentiated into astrocytes after grafting into the spinal cord. In the present study, we examined whether CPECs from rats at postnatal 1 day (P1), 7 day (P7), and 8 weeks (P8W) can function as neural progenitor cells that give rise to neurons and glial cells. Cell spheres were produced in cultures of whole tissue of the choroid plexus from the fourth ventricle of rats at each postnatal period. beta-tubulin class III (Tuj-1), glial fibrillary acid protein (GFAP)-, and O4-positive cells differentiated from cell spheres in the differentiation medium. We produced a monoclonal antibody 3E6 specifically labeling microvilli of CPECs. Using this monoclonal antibody, CPECs were isolated from the choroid plexus of P8W rats by cell sorter (FACS). Immunocytochemistry confirmed that there was no contamination from fibroblasts, endothelial cells, macrophages, or Schwann cells in the FACS-isolated 3E6-labeled cells. Cell spheres formed in the cultures of these 3E6-labeled CPECs. After expansion, these cell spheres gave rise to Tuj-1- (5%), GFAP- (45%), and O4-positive cells (0.16%). The remaining cells (45%) were unlabeled neural or glial markers. Some CPECs of the P8W rat were immunohistochemically stained with lineage-associated markers of Musashi-1 and epidermal growth factor-receptor (EGF-R). In addition, infusion of EGF or fibroblast growth factor-2 (FGF2) into the ventricle increased the number of bromodeoxyuridine (BrdU)-positive cells among CPECs from 0.03% (untreated) to 1.14% (38-fold, EGF) and 1.03% (35-fold, FGF2), respectively. These findings indicate that neural progenitor cells exist among CPECs in the rat.  相似文献   
84.
85.

Background  

Band erosion is reported with a highly variable incidence (0.3–14%) after laparoscopic adjustable gastric banding. Removal of the band is mandatory because the patient regains weight and may become symptomatic, but no consensus exists about the best method, surgical or endoscopic, for this purpose. This study aimed to evaluate the feasibility and effectiveness of endoscopic management of band erosion.  相似文献   
86.
Compelling evidences suggest that increased production of osteoclastogenic cytokines by activated T cells plays a relevant role in the bone loss induced by estrogen deficiency in the mouse. However, little information is available on the role of T cells in post-menopausal bone loss in humans. To investigate this issue we have assessed the production of cytokines involved in osteoclastogenesis (RANKL, TNFalpha and OPG), in vitro osteoclast (OC) formation in pre and post-menopausal women, the latter with or without osteoporosis. We evaluated also OC precursors in peripheral blood and the ability of peripheral blood mononuclear cells to produce TNFalpha in both basal and stimulated condition by flow cytometry in these subjects. Our data demonstrate that estrogen deficiency enhances the production of the pro-osteoclastogenetic cytokines TNFalpha and RANKL and increases the number of circulating OC precursors. Furthermore, we show that T cells and monocytes from women with osteoporosis exhibit a higher production of TNFalpha than those from the other two groups. Our findings suggest that estrogen deficiency stimulates OC formation both by increasing the production of TNFalpha and RANKL and increasing the number of OC precursors. Women with post-menopausal osteoporosis have a higher T cell activity than healthy post-menopausal subjects; T cells thus contribute to the bone loss induced by estrogen deficiency in humans as they do in the mouse.  相似文献   
87.
Background Although the feasibility of laparoscopic resection of gastric gastrointestinal stromal tumors (GISTs) has been established, various aspects are debated. This paper describes the problems of minimally invasive resection of gastric GISTs and compares this experience with an extensive literature review. Study Design Between August 2001 and December 2006, 21 consecutive patients undergoing laparoscopic resection of gastric GISTs were enrolled in a prospective study. A literature review of laparoscopic treatment was performed on Pubmed using keywords GIST and surgery. A comparison with authors’ experience with open wedge-segmental resection of GISTs (25 cases from November 1995 to December 2000) was also carried out. Statistical analysis was based on chi-squared test and t Student evaluation. Results Twenty-one patients, mean age 50.1 years (range, 34–68 years), were submitted to laparoscopic wedge- segmental gastric resections. Mean tumor size was 4.5 cm (range, 2.0–8.5 cm). Mean operative time was 151 min (range, 52–310 min), the mean blood loss was 101 mL (range, 10–250 mL), and the mean hospital stay was 4.8 days (range 3–7 days). There were no major operative complications or mortalities. All lesions had negative resection margins. At a mean follow-up of 35 months, all patients were disease-free. Morbidity, mortality, length of stay, and oncologic outcomes were comparable to the open surgery retrospective evaluation (p = not significant). Conclusions As found also in the literature review, the laparoscopic resection is safe and effective in treating gastric GISTs. Given these findings as well as the advantages afforded by laparoscopic surgery, a minimally invasive approach should be the preferred surgical treatment in patients with small- and medium-sized gastric GISTs.  相似文献   
88.
The Authors report on a rare case of blunt traumatic injury of the gallbladder. A careful clinical examination, an abdominal ultrasonography and a contrast material-enhanced computed tomography have a primary importance for a correct diagnosis. Laparoscopic surgery has an important diagnostic and, in selected cases, therapeutic role. In all traumatic gallbladder ruptures, after an accurate search of eventual associated injuries of other abdominal organs, cholecystectomy is considered the treatment of choice.  相似文献   
89.
From February 2002 to December 2005, 424 operations for thyroid disease were performed in our institute. Twenty-two patients were suffering from Basedow's disease, 14 female and 8 male, mean age 36 years (range: 23 to 53 years). In each patient the diagnosis of Basedow's disease was made according to common clinical and laboratory criteria, by evaluation of the thyroid hormones, TSH and TRAB. Before operation all patients were rendered euthyroid with antithyroid drug treatment. Fourteen total thyroidectomies (64%) and 8 near-total thyroidectomies (36%) were performed. Postoperative thyroid function status was evaluated before, 3-4 weeks after the operation and then 3, 6,12 and 24 months postoperatively. The patients were classified as euthyroid (FT3-FT4 and TSH normal), hypothyroid (FT3 and/or FT4 reduced and TSH increased), or hyperthyroid (FT3-FT4 increased). In expert hands, surgical treatment appears to be capable of curing the hyperthyroidism of Basedow's disease effectively, with a very low and largely acceptable risk of complications. Among the different types of surgery, total thyroidectomy and near-total thyroidectomy are equally appropriate to ensure there is no risk of recurrence of hyperthyroidism.  相似文献   
90.
A 69-year-old man with hepatoma was scheduled for laparoscopic percutaneous transthoracic radiofrequency ablation (RFA) under general anesthesia. His history and physical examination were unremarkable. Anesthesia was induced with propofol and maintained with oxygen-air, sevoflurane and fentanyl. After pneumoperitoneum was introduced, percutaneous RFA needle was inserted into the hepatoma crossing the thoracic cavity and diaphragm several times. Sixty-five minutes after the start of pneumoperitoneum, breathing sounds gradually decreased over the right side of the chest. Because his oxygenation and hemodynamics were stable, the operation was continued with pneumoperitoneum. At the end of surgery, breathing sounds were hardly audible over the right side of the chest. Postoperative chest X-ray showed right pneumothorax. Following thoracentesis, the patient was successfully extubated. During laparoscopic percutaneous transthoracic radiofrequency ablation for liver tumors in the hepatic dome, pneumothorax can occur easily due to passage of peritoneal gas through lesion of the diaphragm caused by RFA needle. We anesthesiologist should recognize the risk of this operation.  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