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   15262篇
  免费   831篇
  国内免费   81篇
耳鼻咽喉   79篇
儿科学   308篇
妇产科学   359篇
基础医学   2041篇
口腔科学   570篇
临床医学   1305篇
内科学   4261篇
皮肤病学   337篇
神经病学   1468篇
特种医学   423篇
外科学   2033篇
综合类   72篇
一般理论   3篇
预防医学   799篇
眼科学   222篇
药学   844篇
中国医学   45篇
肿瘤学   1005篇
  2023年   109篇
  2022年   225篇
  2021年   492篇
  2020年   253篇
  2019年   343篇
  2018年   476篇
  2017年   308篇
  2016年   387篇
  2015年   406篇
  2014年   581篇
  2013年   726篇
  2012年   1173篇
  2011年   1197篇
  2010年   661篇
  2009年   637篇
  2008年   1045篇
  2007年   1048篇
  2006年   987篇
  2005年   863篇
  2004年   802篇
  2003年   703篇
  2002年   700篇
  2001年   146篇
  2000年   147篇
  1999年   167篇
  1998年   128篇
  1997年   137篇
  1996年   109篇
  1995年   92篇
  1994年   85篇
  1993年   72篇
  1992年   89篇
  1991年   93篇
  1990年   80篇
  1989年   70篇
  1988年   57篇
  1987年   56篇
  1986年   55篇
  1985年   33篇
  1984年   52篇
  1983年   40篇
  1982年   32篇
  1981年   24篇
  1980年   23篇
  1979年   27篇
  1977年   31篇
  1975年   21篇
  1974年   21篇
  1972年   25篇
  1970年   20篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
101.
Ectopic breast tissue occurs in 0.4-6% of the general population. Usually, these tissues develop along the embryonic milk line but other sites are reported in the literature. Accessory breasts are commonly axillary and may undergo hormonal changes. Some pathologies of normally positioned breasts can occur in ectopic breast tissue, including carcinoma, and therefore require traditional senological flow-charts and imaging strategies. Supernumerary nipples are generally asymptomatic but may sometimes be associated with urological malformations. In our 10-year experience, 208 patients were observed (138 polythelia and 70 polymastia) and 159 surgical procedures were performed, 97 for supernumerary nipple excision and 67 for accessory breast ablation. Five neoplastic lesions and 25 fibrocystic mastopathies were detected in specimens; normal nipple or breast tissue was found in 129. In view of the potentially malignant transformation of accessory breasts, thorough physician evaluation is needed. Surgery is currently suggested in cases of suspected malignancy, in symptomatic cases and for cosmetic problems.  相似文献   
102.

Background

Functional rehabilitation of patients afflicted with severe mandibular and maxillary alveolar atrophy might be challenging especially in malformed patients.

Methods

Treatment planning using sinus lifting and implant placement before Le Fort I maxillary osteotomy in a patient with severe mandibular and posterior maxillary alveolar atrophy and skelettal class-III conditions due to cleft palate are described.

Results

A full functional and esthetic rehabilitation of the patient was achieved by a stepwise surgical approach performed through sinus lifting as the primary approach followed by implant placement and subsequent Le Fort I maxillary osteotomy to correct the maxillo-mandibular relation.

Conclusion

Stabilisation of the maxillary complex by a sinus lifting procedure in combination with computer aided implant placement as preorthodontic planning procedure before Le Fort I maxillary osteotomy seems to be suitable in order to allow ideal oral rehabilitation especially in malformed patients.  相似文献   
103.
目的评估十二指肠-空肠导管(Endoluminal Duodeno-Jejunal Tube,EDJT)在活体猪实验动物模型中减缓体重增加的可行性,及其在中短期生存中的安全性。方法本项研究共用8只45kg重的Yorkshire猪,其中3只置入180emEDJT,1只置入360cm EDJT,另4只猪作为对照组。切开十二指肠,将EDJT导管缝合固定在十二指肠近Vater壶腹起始处。结果评估全部猪的不适反应和体重,每日一次,共7周,未发现严重并发症发生。术后7周3组动物的平均体重变化百分率:对照组、180cm组和360cm组分别是22.5%,6%和-2.8%。EDJT组(180cm组、360cm组)体重增加明显减慢,与对照组相比,有统计学意义(P=0.05)。结论EDJT可以安全使用,无肠梗阻、肠套叠或胰腺炎等并发症发生。EDJT可明显减缓体重增加。  相似文献   
104.
Background Exploratory laparoscopy is commonly undertaken in patients with highly suspicious biliary and pancreatic lesions to facilitate diagnosis and staging cancer is present. If an unresectable tumor is identified, a second endoscopic procedure may be required do deploy a self-expandable metal stent (SEMS) for palliation. As endoscopic retrograde cholangio pancreatography (ERCP) may be unsuccessful in up to 20% of patients, we evaluated the feasibility and safety of deployment of self-expandable metal stents at the same time as the initial laparoscopy. Patients and Methods A total of 23 eligible patients (8 male and 15 female) with malignant obstruction of the common bile duct underwent deployment of SEMS at laparoscopy. Primary outcome measure was the successful laparoscopic deployment of stent and secondary outcome measure was complications rates. Results Indications for stent deployment were unresectable pancreatic cancer in 18, cholangiocarcinoma in two, neuroendocrine tumor in one and ampullary adenocarcinoma in two patients. The median age was 73 years (range 49–93). Twenty-two of 23 stents were deployed successfully: 17 stents were deployed transcystically and five via a choledochotomy. Median times for laparoscopic exploration and SEMS deployment were 165 min (range 105–230) and 20 min (range 10–50), respectively. Pre- and post-procedures median total bilirubin were 9.4 mg/dl (range 5.4–17.5) and 4.0 (range 2.6–7.1). The median size of the pancreatic mass was 3 cm (range 2–5 cm) and that of the common bile duct (CBD) from 9.2 mm (range 7.2–17.4). The mean duration of laparoscopy was 170 min (range 120–230 min) and that for stent deployment 23 min (range 10–50 min). Complications included bleeding, obstruction, and wound infection. Bleeding occurred on day 7 in two patients and on day 30 in one patient; bleeding occurred at the gastrojejunal anastomosis site and was successfully treated with endoscopic hemostasis. A total of three stent obstructions were identified: one each at 60, 90, and 120 days follow-up. All complications were successfully managed endoscopically. There were a total of seven deaths, six as a result of progressive cancer and one of surgical wound infection and ensuing complications. Conclusion This study demonstrates that laparoscopic deployment of self-expandable metal bile duct stents is feasible and safe. This option appears to be a reasonable option in patients with inoperable malignant obstruction of the distal common bile duct.  相似文献   
105.
BACKGROUND: Subthalamic Deep Brain Stimulation is a valid surgical procedure for the treatment of idiopathic PD, although its precise mechanism of action is still unclear; moreover, there are no conclusive data about the functional anatomy of the human subthalamic region. Identifying the location of active contacts for StnDBS can yield interesting insights on the mechanisms of action of DBS and the different role played by the anatomical structures of the subthalamic region. METHODS: Twenty-five patients operated on for bilateral StnDBS were considered. During the surgical procedure, a complete intraoperative neurophysiological study was obtained by means of semimicrorecordings and stimulations. After surgery, an MRI study confirmed the position of the electrodes; MR images were subsequently superimposed onto a stereotactic atlas by using a dedicated workstation. The coordinates relative to the tip of the electrodes and active contacts were then calculated. RESULTS: Most of the electrode tips are located inside the subthalamus or immediately ventrally to it. Of the active contacts used for chronic stimulation, 96.5% are located in a well-defined anatomical region, which includes subthalamus, zona incerta, and FF. CONCLUSIONS: Our findings seem to suggest that other structures beyond the subthalamus itself play a clinical role in symptoms control after DBS for PD.  相似文献   
106.

Background

The first reliable statistic data about perioperatory mortality were published in 1841 by the French Joseph-Francois Malgaigne (1806–1863): he referred to a mean mortality of 60% for amputations and this bad result was to be attributed mainly to hospital acquired diseases. The idea of “hospital acquired disease” although vague, included five infective nosologic entities, which at that time were diagnosed more frequently: erysipelas, tetan, pyemia, septicemia, and gangrene. Nonetheless, the suppuration with pus production was considered from most of the surgeons and doctors of that time as a necessary and unavoidable step in the process of wound healing. During the end of the eighteenth century, hospitals of the main European cities were transforming into aggregations of several wards, where the high concentration of patients created poor sanitary conditions and a consistent increase of perioperatory mortality. In 1865, Lister applied his first antiseptic dressing on the surface of an exposed fracture. These experimental attempts lead to an effective reduction of wound infections respect to the dressing with strings used previously.

Discussion

Lister's innovations in the field of wound treatment were based on two brand new concepts: germs causing rot were ubiquitarious and the wound infection was not a normal step in the process of wound healing. The concept of antisepsis was hardly accepted in the European surgical world: “Of all countries, Italy is the most indifferent and uninterested in experimenting this method, which has been so favorably judged from the greatest surgical societies in Germany”. This quotation from the young surgeon Giuseppe Ruggi (1844–1925) from Bologna comes from his article where he presented his first experiences on aseptic medications started the previous year in the Surgical Department of Maggiore Hospital in Bologna. In his report, Ruggi described the adopted technique and suggested that the medication should be extended to all the surgical patients of the hospital:“… this is needed to totally remove from the hospital all those elements of infection which grow in the wounds dressed with the old method”. The experimentation of this new dressing for the few treated cases was rigorous and concerned both the sterilization of surgical tools with the fenic acid (5%) and the shaving of the skin. Ruggi also observed that there was no correlation between the seriousness of the wound and its extension or way of healing: when “simple” cases that “should heal without complication” showed fever he often realized that “it was often due to a medication performed without following the rules for an accurate disinfection and dressing”. Ruggi thought that the fever was connected to “reabsorption of pyrogenic substances, which can be removed cleaning and disinfecting the wound” in cases of wounds not accurately dressed and rarely medicated. Frequent postoperative medications of the wound were able to eliminate the fever within 2 h. Ruggi's attitude toward the fine reasoning lead him to introduce the concept of immunodeficiency related to physical deterioration: “… patients treated for surgical disease may sometimes suffer from complications of medical conditions, which initially escape the most accurate investigations… The surgical operation could, in some cases, hold the balance of power”.

Conclusions

The obtained results, published in 1879, appear extremely interesting. As he wrote in 1898, for the presentation of his case record of more than 1000 laparotomies, he had started “… operating as a young surgeon without any tutor, helped only by his mind and what he could deduce from publications existing at the moment …”.  相似文献   
107.

Introduction

Vitamin D insufficiency (VDI) has been associated with increased cardiovascular risk in the non-HIV population. This study evaluates the relationship among serum 25-hydroxyvitamin D [25(OH)D] levels, cardiovascular risk factors, adipokines, antiviral therapy (ART) and subclinical atherosclerosis in HIV-infected males.

Methods

A cross-sectional study in ambulatory care was made in non-diabetic patients living with HIV. VDI was defined as 25(OH)D serum levels <75 nmol/L. Fasting lipids, glucose, inflammatory markers (tumour necrosis factor-α, interleukin-6, high-sensitivity C-reactive protein) and endothelial markers (plasminogen activator inhibitor-1, or PAI-I) were measured. The common carotid artery intima-media thickness (C-IMT) was determined. A multivariate logistic regression analysis was made to identify factors associated with the presence of VDI, while multivariate linear regression analysis was used to identify factors associated with common C-IMT.

Results

Eighty-nine patients were included (age 42±8 years), 18.9% were in CDC (US Centers for Disease Control and Prevention) stage C and 75 were on ART. VDI was associated with ART exposure, sedentary lifestyle, higher triglycerides levels and PAI-I. In univariate analysis, VDI was associated with greater common C-IMT. The multivariate linear regression model, adjusted by confounding factors, revealed an independent association between common C-IMT and patient age, time of exposure to protease inhibitors (PIs) and impaired fasting glucose (IFG). In contrast, there were no independent associations between common C-IMT and VDI or inflammatory and endothelial markers.

Conclusions

VDI was not independently associated with subclinical atherosclerosis in non-diabetic males living with HIV. Older age, a longer exposure to PIs, and IFG were independent factors associated with common C-IMT in this population.  相似文献   
108.
BackgroundBrain death (BD) and cold preservation are major risk factors for an unfavorable transplantation outcome. Although donor dopamine treatment in brain-dead rats improves renal function and histology in allogeneic recipients, it remains to be assessed if this also holds true for the combinations of BD and prolonged static cold preservation.MethodsBD was induced in F344 donor rats, which were subsequently treated with NaCl 1 mL/h (BD, n = 11), NaCl/hydroxy ethyl starch (BD-norm, n = 10), or 10 μg/min/kg dopamine (BD-dopa, n = 10). Renal grafts were harvested 4 h after BD and transplanted into bilateral nephrectomized Lewis recipients 6 h after cold preservation in University of Wisconsin solution. Renal function was evaluated by use of serum creatinine and urea concentrations at days 0, 1, 3, 5, and 10. Ten days after transplantation, recipients were killed and the renal allografts were processed for light microscopy and immune histology.ResultsSerum urea concentrations at days 5 and 10 were significantly lower in recipients that received a renal graft from dopamine-treated rats; for serum creatinine, only a trend was observed at day 10. Immune histology revealed a lower degree of ED1-positive cells in the donor dopamine-treated group. Under light microscopy, Banff classification revealed significantly less intimal arteritis in these grafts (P < .05).ConclusionsAlthough donor dopamine treatment clearly improves renal histology in this model, the beneficial effect on early renal function was marginal. It remains to be assessed if donor dopamine treatment has a beneficial effect on renal function in long-term follow-up.  相似文献   
109.

Background

Several studies have demonstrated skills transfer after virtual reality (VR) simulation training in laparoscopic surgery. However, the impact of VR simulation training on transfer of skills related to laparoscopic colectomy remains not investigated. The present study aimed at determining the impact of VR simulation warm-up on performance during laparoscopic colectomy in the porcine model.

Methods

Fourteen residents naive to laparoscopic colectomy as surgeons were randomly assigned in block to two groups. Seven trainees completed a 2-h VR simulator training in the laparoscopic sigmoid colectomy module (study group). The remaining seven surgeons (control group) underwent no intervention. On the same day, all participants performed a sigmoid colectomy with anastomosis on a pig. All operations were video recorded. Two board-certified expert colorectal surgeons independently assessed performance during the colectomy on the swine. Examiners were blinded to group assignment. The two examiners used a previously validated clinical instrument specific to laparoscopic colectomy. The primary outcome was the generic and specific skills score values.

Results

Surgeons undergoing short-duration training on the VR simulator performed significantly better during laparoscopic colectomy on the pig regarding general and specific technical skills evaluation. The average score of generic skills was 17.2 (16.5–18) for the control group and 20.1 (16.5–22) for the study group (p = 0.002). The specific skills average score for the control group was 20.2 (19–21.5) and 24.2 (21–27.5) for the study group (p = 0.001). There was acceptable concordance (Kendall’s W) regarding the video assessment of generic (W = 0.78) and specific skills (W = 0.84) between the two examiners.

Conclusions

A single short-duration VR simulator practice positively impacted surgeons’ generic and specific skills performance required to accomplish laparoscopic colectomy in the swine model.  相似文献   
110.

Introduction

Conversion to laparoscopic gastric bypass (LRYGB) appears to be the treatment of choice after failed LAGB. To reduce the risk of postoperative complications, some surgeons routinely adopt a two-stage strategy. The purpose of this study was to analyze our institution’s experience with the two-stage procedure for LAGB conversion to LRYGB

Materials and Methods

The bariatric database of our institution was reviewed to identify patients who had undergone conversion of LAGB to LRYGB from November 2007 to June 2012.

Results

One hundred patients were included. Of these, 62 (62 %) required conversion to LRYGB for inadequate weight loss or weight regain and 38 for band-related complications. All the procedures were performed in two stages and laparoscopically. The average time between band removal and LRYGB was 17.3 months. The mean follow-up after LRYGB was 31?±?18.7 months. The mean BMI prior to LRYGB conversion was 45.3?±?5.2. Early complications occurred in 15 patients (15 %), while late complications occurred in only 3 patients (3 %). The average %EWL at 24 months and 48 months after conversion was 70.1 and 69.4 %, respectively.

Conclusion

Although a two-stage conversion strategy increases the number of operations and hospital stay without decreasing the rate of early complications compared to one-stage conversion; it has shown to be associated with low rates of GJA stenosis and excellent %EWL.  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