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   9433篇
  免费   605篇
  国内免费   76篇
耳鼻咽喉   160篇
儿科学   241篇
妇产科学   282篇
基础医学   1101篇
口腔科学   141篇
临床医学   878篇
内科学   2354篇
皮肤病学   137篇
神经病学   991篇
特种医学   281篇
外科学   1628篇
综合类   85篇
一般理论   2篇
预防医学   620篇
眼科学   77篇
药学   521篇
  1篇
中国医学   28篇
肿瘤学   586篇
  2024年   12篇
  2023年   79篇
  2022年   209篇
  2021年   367篇
  2020年   193篇
  2019年   321篇
  2018年   336篇
  2017年   229篇
  2016年   282篇
  2015年   338篇
  2014年   414篇
  2013年   539篇
  2012年   805篇
  2011年   800篇
  2010年   408篇
  2009年   353篇
  2008年   626篇
  2007年   675篇
  2006年   587篇
  2005年   558篇
  2004年   503篇
  2003年   483篇
  2002年   377篇
  2001年   57篇
  2000年   48篇
  1999年   47篇
  1998年   57篇
  1997年   33篇
  1996年   36篇
  1995年   33篇
  1994年   21篇
  1993年   24篇
  1992年   16篇
  1991年   17篇
  1990年   20篇
  1989年   25篇
  1988年   11篇
  1987年   12篇
  1986年   8篇
  1985年   16篇
  1984年   11篇
  1983年   17篇
  1982年   15篇
  1981年   11篇
  1980年   8篇
  1979年   8篇
  1977年   6篇
  1976年   8篇
  1974年   7篇
  1971年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
BackgroundClostridioides difficile infection (CDI) is traditionally taught to be an antibiotic associated diarrheal infection. This diagnosis is based on the presence of clinical symptoms (usually defined as more than 3 watery, loose or unformed stool within 24 h) coupled with a diagnostic test. There is now a new presentation of CDI, including progression to toxic megacolon, in patients without diarrhea.MethodsWe report a case series of 9 surgical patients from a single institution who developed CDI without preceding diarrhea.ResultAll 9 patients had CDI with positive laboratory testing for C. difficile toxin. They, however, presented with a lack of or minimal bowel movements. Six patients had rapid development of abdominal distention, 1 patient had a single episode of watery stool in 3 days, while the other 2 patients presented with constipation. Seven patients received stool softeners, suppositories and/or enemas for presumed constipation. Four patients had a mild course of infection and were successfully treated medically. The other 5 patients developed toxic megacolon, and eventually required total abdominal colectomy. Out of the 5 patients that required total colectomy, 2 expired.ConclusionCDI must be suspected in patients who rapidly develop abdominal distention, vague abdominal complaints or change in bowel function even in the absence of diarrhea, especially if coupled with multi-system organ failure.  相似文献   
52.
IntroductionFibroepithelial polyps (FEP) of the lower urinary tract are relatively common in adults but rare in children, with fewer than 250 cases reported in the literature to date.ObjectiveThe aim of this study was to address the experience of FEP management in children.Study designA retrospective multicenter review was undertaken in children with defined FEP of the lower urinary tract managed between 2008 and 2018. The data at 18 pediatric surgery centers were collected. Their demographic, radiological, surgical, and pathological information were reviewed.ResultsA total of 33 children (26 boys; 7 girls) were treated for FEP of the lower urinary tract at 13 centers. The most common presentation was urinary outflow as hematuria (41%), acute urinary retention (25%), dysuria (19%), or urinary infections (28%). A prenatal diagnosis was made for three patients with hydronephrosis. Almost all of the children (94%) underwent ultrasound imaging of the urinary tract as the first diagnostic examination, 23 (70%) of them also either had an MRI (15%), cystourethrography (25%), computerized tomography (6%), or cystoscopy (45%). Two of these children (6%) had a biopsy prior to the surgery. The median preoperative delay was 7.52 (range: 1–48) months. Most of the patients were treated endoscopically, although four (12.1%) had open surgery and two (6.1%) had an additional incision for specimen extraction. The median hospital stay was 1.5 (range: 1–10) days. There were no recurrences and no complications after a median follow-up of 13 (range: 1–34) months.DiscussionThe main limitation of our study is the retrospective design, although it is the largest one for this pathology.ConclusionThis series supports sonography as the most suitable diagnosis tool before endoscopy to confirm the diagnosis and to perform the resection for most FEP in children. This report confirms the recognized benign nature in the absence of recurrences.Level of EvidenceLevel V.  相似文献   
53.
During aging, changes in endosteal and periosteal boundaries of cortical bone occur that differ between men and women. We here develop a new procedure that uses high-resolution peripheral quantitative CT (HR-pQCT) imaging and 3D registration to identify such changes within the timescale of longitudinal studies. A first goal was to test the sensitivity of the approach. A second goal was to assess differences in periosteal/endosteal expansion over time between men and women. Rigid 3D registration was used to transform baseline and all follow-up (FU) images to a common reference configuration for which the region consisting of complete slices (largest common height) was determined. Periosteal and endosteal contours were transformed to the reference position to determine the net periosteal and endosteal expansion distances. To test the sensitivity, images from a short-term reproducibility study were used (15 female, aged 21 to 47 years, scanned three times). To test differences between men and women, images from a subset of the Geneva Retirees Cohort were used (248 female, 61 male, average age 65 years, 3.5 and 7 years FU). The sensitivity study indicated a least significant change for detecting periosteal/endosteal expansion of 41/31 microns for the radius and 17/26 microns for the tibia. Results of the cohort study showed significant net endosteal retraction only in females at the radius and tibia after 3.5 years (38.0 and 38.4 microns, respectively) that further increased at 7 years FU (70.4 and 70.8 microns, respectively). No significant net periosteal changes were found for males or females at 7 years. The results demonstrate that it is possible to measure changes in endosteal contours in longitudinal studies within several years. For the investigated cohort, significant endosteal retraction was found in females but not in males. Whether these changes in cortical geometry are related to fracture risk remains to be investigated in larger cohorts © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).  相似文献   
54.
ObjectivesTo assess potential nosocomial coronavirus disease-2019 (COVID-19) transmission in patients who underwent robot-assisted laparoscopic procedures during the pandemic.Material and methodsProspective study in patients undergoing robot-assisted laparoscopy in urology or gynaecology within 2 academic hospitals. Patients underwent local preoperative COVID-19 screening using a symptoms questionnaire. Patients with suspicious screening underwent coronavirus real time-polymerase chain reaction (RT-PCR) and were excluded from robotic surgery if positive. Patients with symptoms postsurgery were systematically tested for coronavirus by RT-PCR. One-month postsurgery, all patients had a telephone consultation to evaluate COVID-19 symptoms.ResultsSixty-eight patients underwent robotic surgery during the study period (median age: 63-years [IQR: 53–70], 1.8 male: female ratio). Oncology was the main indication for robotic surgery (n = 62, 91.2%) and 26 patients (38.2%) received a chest CT-scan prior to surgery. Eleven patients (16.2%) were symptomatic after surgery of whom only 1 tested positive for coronavirus by RT-PCR (1.5%) and was transferred to COVID-19 unit with no life-threatening condition. No attending surgeon was diagnosed with COVID-19 during the study.ConclusionsRobot-assisted laparoscopic surgery seemed safe in the era of COVID-19 as long as all recommended precautions are followed. The rate of nosocomial COVID-19 transmission was extremely low despite the fact that we only used RT-PCR testing in symptomatic patients during the preoperative work-up. Larger cohort is needed to validate these results.  相似文献   
55.

The attitudes of medical students toward transgender people have important implications for the future quality of healthcare for Caribbean transgender patients. This paper examined the attitudes and beliefs of Caribbean medical students toward transgender people, provides psychometric evaluation of a promising instrument, and considers implications for the development of transgender curricula in Caribbean medical education. Medical students (N?=?205; 155 women, 43 men, 7 unstated) enrolled at a publicly supported Caribbean university completed the Transgender Attitudes and Beliefs Scale (TABS; Kanamori et al., 2017). Internal consistency was strong for the total TABS (α?=?.93) and more variable for the three subscales: interpersonal comfort (IC: α?=?.91), sex/gender beliefs (SGB: α?=?.89), and human value (HV: α?=?.74). Confirmatory factor analysis demonstrated acceptable overall fit for the three-factor model. There were no significant gender differences in overall attitudes toward transgender people as measured by the total TABS score; women reported higher IC scores. Scores were not correlated with age or with year in medical school. Students reported significantly more tolerant attitudes on the HV scale than on IC or SGB scales. Psychometric findings establish measurement invariance and provide support for further use of the TABS in the Caribbean. We discuss implications for medical curriculum development, including use of the TABS as a tool for medical students to reflect on their individual attitudes and beliefs regarding transgender people.

  相似文献   
56.
Liver resection still represent the treatment of choice for liver malignancies, but in some cases inadequate future remnant liver (FRL) can lead to post hepatectomy liver failure (PHLF) that still represents the most common cause of death after hepatectomy. Several strategies in recent era have been developed in order to generate a compensatory hypertrophy of the FRL, reducing the risk of post hepatectomy liver failure. Portal vein embolization, portal vein ligation, and ALLPS are the most popular techniques historically adopted up to now. The liver venous deprivation and the radio-embolization are the most recent promising techniques. Despite even more precise tools to calculate the relationship among volume and function, such as scintigraphy with 99mTc-mebrofenin (HBS), no consensus is still available to define which of the above mentioned augmentation strategy is more adequate in terms of kind of surgery, complexity of the pathology and quality of liver parenchyma. The aim of this article is to analyse these different strategies to achieve sufficient FRL.  相似文献   
57.
Bulletin of Environmental Contamination and Toxicology - The holistic approach of Driver-Pressure-State-Impact-Response (DPSIR) methodology was applied to selected Cr(VI) impacted groundwater...  相似文献   
58.
Background: Occult choroidal neovascularization (CNV), poorly defined on fluorescein angiography, is present in the majority of patients with exudative complications of age-related macular degeneration. For patients who present with this type of subfoveal CNV but who have useful visual acuity, no form of treatment is of proven benefit. Accordingly, a pilot randomized trial of indirect laser treatment was performed. The rationale of this treatment was to inhibit the CNV through laser-induced effects on the retinal pigment epithelium. Methods: Patients with occult subfoveal CNV without retinal pigment epithelial detachment and with visual acuity of 20/200 or better were randomized to treatment or control groups. A grid of laser burns was applied to the macula beyond the area of serous retinal detachment and of angiographically defined occult CNV Results: After an average follow-up of 38 months, there was no difference in mean final visual acuity (0.12 treated, 0.14 control) or clinical outcome between treated and untreated groups. Fluorescein angiography showed gradual enlargement in the occult CNV in 58% of eyes in both groups. A decrease in visual acuity to worse than 20/200 (54% of treated, 50% of control eyes) was associated with ingrowth of well-delineated CNV (6 treated, 7 control eyes) or progression to a fibroglial or atrophic scar (11 treated, 8 control eyes). Conclusions: No benefit was demonstrated for scatter photocoagulation of the macula in patients with age-related macular degeneration and occult subfoveal CNV with initially good visual acuity. There were, however, no complications related to treatment.  相似文献   
59.
In this paper we use nonparametric mathematical programming models to compute and decompose Malmquist indices of productivity and quality change, which are used to evaluate the reforms in the UK National Health Service in the early nineties. We focus on acute hospitals and we study them over the first five years of the reforms. The findings of the study indicate that there was a productivity slowdown in the first year after the reforms but productivity progress in the subsequent years and thus, overall there was a net gain in productivity over the entire period considered. Productivity trends were dominated by technical change rather than hospital relative efficiency changes, as hospitals were already largely relatively efficient at the time of the introduction of the reforms. In fact, over the last four years in the period studied there was small relative efficiency regress and this does not bear out the argument that the reforms would increase hospital efficiency. The productivity changes are similar when service quality is incorporated in the analysis but the magnitude of these changes diminishes. Quality of service followed different trends to productivity change and this may have been the price for the productivity gains achieved.  相似文献   
60.
Duchenne muscular dystrophy (DMD), a severe X-linked recessive disorder which results in progressive muscle degeneration, is due to a lack of dystrophin, a membrane cytoskeletal protein. An approach to treatment is to compensate for dystrophin loss with utrophin, another cytoskeletal protein with over 80% homology with dystrophin. Utrophin is expressed, at the neuromuscular junction, in normal and DMD muscles and there is evidence that it may perform the same cellular functions as dystrophin. So, the identification of molecules or drugs that could up-regulate utrophin is a very important goal for therapy. We show that in adult normal and mdx mice (an animal model of Duchenne myopathy) treated with -arginine, the substrate of nitric oxide synthase (NOS), a pool of utrophin localized at the membrane appeared and increased, respectively. In normal and mdx myotubes in culture, -arginine, nitric oxide (NO), or hydroxyurea increased utrophin levels and enhanced its membrane localization. This effect did not occur with -arginine, showing the involvement of NOS in this process. The NO-induced increase in utrophin was prevented by oxadiazolo-quinoxalin-1-one, an inhibitor of a soluble guanylate cyclase implicated in NO effects. These results open the way to a potential treatment for Duchenne and Becker dystrophies.  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