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   11314篇
  免费   847篇
  国内免费   92篇
耳鼻咽喉   89篇
儿科学   333篇
妇产科学   265篇
基础医学   1267篇
口腔科学   172篇
临床医学   1045篇
内科学   2400篇
皮肤病学   148篇
神经病学   817篇
特种医学   393篇
外科学   1778篇
综合类   255篇
一般理论   7篇
预防医学   687篇
眼科学   976篇
药学   736篇
中国医学   70篇
肿瘤学   815篇
  2024年   13篇
  2023年   104篇
  2022年   140篇
  2021年   294篇
  2020年   184篇
  2019年   268篇
  2018年   305篇
  2017年   208篇
  2016年   204篇
  2015年   251篇
  2014年   320篇
  2013年   401篇
  2012年   620篇
  2011年   683篇
  2010年   401篇
  2009年   361篇
  2008年   604篇
  2007年   699篇
  2006年   669篇
  2005年   647篇
  2004年   587篇
  2003年   541篇
  2002年   498篇
  2001年   442篇
  2000年   395篇
  1999年   321篇
  1998年   113篇
  1997年   88篇
  1996年   84篇
  1995年   65篇
  1994年   64篇
  1993年   63篇
  1992年   177篇
  1991年   173篇
  1990年   149篇
  1989年   117篇
  1988年   125篇
  1987年   141篇
  1986年   101篇
  1985年   95篇
  1984年   59篇
  1983年   72篇
  1982年   47篇
  1981年   41篇
  1980年   42篇
  1979年   67篇
  1978年   47篇
  1977年   20篇
  1973年   16篇
  1972年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
PURPOSE: Lumbar subarachnoid catheters for cerebrospinal fluid (CSF) drainage (lumbar drains) are indicated for several medical and surgical conditions. A number of complications can occur from the placement of this type of catheter, including catheter breakage from excessive traction or shearing over the Tuohy needle. CLINICAL FEATURES: Five cases of lumbar subarachnoid catheter breakage/shearing and catheter fragment retention, as well as one near miss, were identified over a one-year period at a single institution. All (n = 6) patients were undergoing neurosurgical procedures. Four patients required surgical retrieval of the catheter fragments. No patient experienced log-term neurological sequelae. DISCUSSION: From these experiences, the following risks factors for catheter rupture are identified: 1) intentional or accidental retraction of the catheter through the needle during placement; 2) faulty use of the guidewire; or 3) use of excessive force during removal of the catheter. Methods to prevent such complications are suggested, including minimal use, or complete avoidance of a guidewire.  相似文献   
102.
The objective of this report is to describe cerebral autoregulation after severe inflicted pediatric traumatic brain injury (iTBI). We examined cerebral autoregulation of both cerebral hemispheres (mean autoregulatory index; ARI) in children <5 years with Glasgow Coma Scale (GCS) score of <9 and no evidence of brain death within the first 48 h of pediatric intensive care unit (PICU) admission. Discharge and 6-month Glasgow Outcome Scale (GOS) scores were collected. GOS of <4 reflected poor outcome. All three iTBI and all seven noninflicted TBI (nTBI) patients had admission GCS score of <9. Eight of 10 patients had Autoregulatory Index (ARI) of <0.4 (impaired cerebral autoregulation) of at least one hemisphere. All children with iTBI had poor outcome, and none had intact cerebral autoregulation in both hemispheres. Children with nTBI had better overall outcome than those with iTBI. Two of the children with nTBI had intact autoregulation in both hemispheres and good outcome. Two of the three children with iTBI had differential effects on autoregulation between hemispheres despite bilateral injury. These are, to our knowledge, the first data on cerebral blood flow autoregulation in the unique setting of iTBI and provide a rationale for further study of their relationship to outcome and effects of therapy.  相似文献   
103.
OBJECTIVE: Distal embolization of plaque or thrombus may cause organ ischemia following percutaneous peripheral interventions. The purpose of this study was to evaluate the incidence and clinical significance of particulate embolization during percutaneous superficial femoral artery (SFA) intervention by monitoring with continuous Doppler ultrasound. The rate and timing of embolization at various phases of intervention such as guidewire crossing, balloon angioplasty, stent deployment, and directional atherectomy were analyzed and compared. METHODS: Sixty patients underwent SFA intervention. Of these 60 patients, 10 patients underwent percutaneous transluminal angioplasty (PTA) alone, 40 patients underwent PTA with stenting, and 10 patients underwent plaque excision with the SilverHawk atherectomy device (8) or Spectranetics excimer laser (2) with or without additional PTA or stent placement. A 4-MHz Doppler probe was used for continuous monitoring in the ipsilateral popliteal artery. Distal embolization was registered as embolic signals (ES). ES were quantitatively assessed during critical portions of the procedure including guidewire crossing, balloon angioplasty, stent deployment and/or atherectomy. ES during different phases of intervention were compared using analysis of variance (ANOVA). RESULTS: ES was noted in every patient during wire crossing, angioplasty, stent deployment and atherectomy. The average number of ES noted during guidewire crossing was 8, PTA was 12, stent deployment was 28, SiverHawk atherectomy was 49, and Spectranetics excimer laser was 51. The frequency of ES was statistically higher during stent deployment vs wire crossing or balloon angioplasty but equivalent to that generated by plaque excision. ES was observed more frequent during balloon angioplasty than during wire crossing. In one patient who was treated with the excimer laser, a single runoff vessel was occluded with embolic debris but patency was restored angiographically after thrombolysis. The patient went on to require below knee amputation. During follow-up, all patients with claudication reported improved symptoms and those with ulcers or gangrene demonstrated healing. The average increase in ankle-brachial index following intervention was 0.31. CONCLUSION: While ES were recorded at each step of SFA intervention, the frequency was greatest during stent deployment. Despite the frequency of these events, only one patient developed angiographically and clinically significant embolization. Thus, our findings do not support the routine use of protection devices during percutaneous SFA intervention.  相似文献   
104.

Background

Laparoscopic distal gastrectomy has been increasingly utilized in the treatment of gastric adenocarcinoma. This study aims to compare the morbidity/mortality and postoperative outcomes of laparoscopic-assisted versus open distal gastrectomy since 2000.

Methods

A comprehensive search of MEDLINE and EMBASE was conducted including studies published between 2000 and present.

Results

Seventeen studies with a total of 7,109 distal gastrectomies (3,496 lap vs 3,613 open) were included. Across all studies, postoperative morbidity rates for laparoscopic gastrectomy were lower than that of open [median (range) 10 (0–36)?% vs 17 (0–43)?%]. Meta-analysis of postoperative morbidity rates in prospective studies only yielded pooled odds ratio of 0.52 (95 % CI 0.33–0.81) (P?=?0.004). In-hospital mortality rates were comparable between the two (range: laparoscopic 0–3.3 vs open 0–6.7 %). The long-term oncological outcomes of resection were difficult to analyze given variable reporting but appeared similar between the two. Meta-analysis of prospective studies showed that laparoscopic-assisted distal gastrectomy was associated with significantly shorter hospital length of stay [standard mean difference (SMD)?=??0.78 (95 % CI?=??1.0 to ?0.56)], comparable intraoperative bleeding [SMD?=?0.64 (95 % CI?=??1.3–0.0430) P?=?0.066] and longer operative time compared to open gastrectomy [1.9 (95 % CI 0.05–3.8) P?=?0.045, with P?<?0.001].

Conclusion

This study supports the use of laparoscopic-assisted distal gastrectomy for treatment of gastric adenocarcinoma with evidence of comparable, if not better, short-term postoperative parameters when compared to open distal gastrectomy. The long-term oncological outcomes appear similar but may require more evaluation.  相似文献   
105.
106.

Context

The European Association of Urology Renal Cell Carcinoma (RCC) Guideline Panel has prepared evidence-based guidelines and recommendations for the management of RCC.

Objective

To provide an updated RCC guideline based on standardised methodology including systematic reviews, which is robust, transparent, reproducible, and reliable.

Evidence acquisition

For the 2019 update, evidence synthesis was undertaken based on a comprehensive and structured literature assessment for new and relevant data. Where necessary, formal systematic reviews adhering to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were undertaken. Relevant databases (Medline, Cochrane Libraries, trial registries, conference proceedings) were searched until June 2018, including randomised controlled trials (RCTs) and retrospective or controlled studies with a comparator arm, systematic reviews, and meta-analyses. Where relevant, risk of bias (RoB) assessment, and qualitative and quantitative syntheses of the evidence were performed. The remaining sections of the document were updated following a structured literature assessment. Clinical practice recommendations were developed and issued based on the modified GRADE framework.

Evidence synthesis

All chapters of the RCC guidelines were updated based on a structured literature assessment, for prioritised topics based on the availability of robust data. For RCTs, RoB was low across studies. For most non-RCTs, clinical and methodological heterogeneity prevented pooling of data. The majority of included studies were retrospective with matched or unmatched cohorts, based on single- or multi-institutional data or national registries. The exception was for the treatment of metastatic RCC, for which there were several large RCTs, resulting in recommendations based on higher levels of evidence.

Conclusions

The 2019 RCC guidelines have been updated by the multidisciplinary panel using the highest methodological standards. These guidelines provide the most reliable contemporary evidence base for the management of RCC in 2019.

Patient summary

The European Association of Urology Renal Cell Carcinoma Guideline Panel has thoroughly evaluated the available research data on kidney cancer to establish international standards for the care of kidney cancer patients.  相似文献   
107.
Pancreaticoduodenectomy combined with portal vein resection is increasingly accepted as a viable treatment option for pancreatic carcinoma with suspected involvement of the portal vein.However, its clinical benefit remains controversial. This study evaluated the outcomes of pancreaticoduodenectomy with portal vein resection for pancreatic carcinoma in a group of Chinese patients operated on by a specialized team in a center with a low case volume of pancreatic cancer. The perioperative and long-term outcomes of 12 patients with portal vein resection for suspected involvement of the portal vein and 38 patients who underwent pancreaticoduodenectomy without portal vein resection during the same period were compared. In the former group, eight patients underwent segmental resection, and four patients underwent wedge resection of the portal vein. There were no significant differences in operative blood loss (median 0.8 vs. 0.8 liter, p = 0.313), hospital mortality (0% vs. 2.6%, p = 1.000), or operative morbidity (41.7% vs. 42.1%, p = 0.979) between the two groups. Patients who required portal vein resection had higher frequencies of microscopic lymphatic permeation (58.3% vs. 18.4%, p = 0.023) and vascular invasion (50.0% vs. 15.8%, p = 0.025). Long-term survival was comparable between patients with portal vein resection and those without it (median 19.5 vs. 20.7 months, p = 0.769). These findings suggest that pancreaticoduodenectomy combined with portal vein resection can be performed safely by a specialized team in a center with a low case volume of pancreatic carcinoma and that it may offer survival benefit in patients with suspected portal vein involvement.  相似文献   
108.
BACKGROUND: Portal venous blood flow may protect adjacent tumour cells from thermal destruction with radiofrequency ablation (RFA). This study aimed to investigate the local effect of RFA on the main portal vein branch, and the completeness of cellular ablation in its vicinity, with or without a Pringle manoeuvre using a porcine model. METHODS: This was an in vivo study on 23 domestic pigs. RFA using a cooled-tip electrode was performed 5 mm from the left main portal vein branch under ultrasonographic guidance for 12 min with (n = 10) or without (n = 10) a Pringle manoeuvre. Ten pigs were killed 4 h after the procedure to study the early effects of RFA and ten others were killed 1 week later to determine any delayed effect. As a control, sham operations with a Pringle manoeuvre for 12 min were performed on three pigs. The flow velocity changes of portal vein and hepatic artery were measured using Doppler ultrasonography, and the completeness of cellular ablation around the portal vein was assessed qualitatively by histochemical staining and quantitatively by measuring intracellular levels of adenosine 5'-triphosphate (ATP). RESULTS: In the absence of the Pringle manoeuvre, there was no significant change in mean(s.d.) portal vein flow velocity before RFA (20.0(3.5) cm/s) and at 4 h (18.5(2.5) cm/s) (P = 0.210) and 1 week (19.5(2.2) cm/s) (P = 0.500) after the procedure. Gross and histological examination of the portal vein branches showed no damage without the Pringle manoeuvre. In all pigs that underwent RFA with a Pringle manoeuvre, the portal vein was occluded 1 week after the operation; histological examination of the affected portal vein showed severe thermal injury and associated venous thrombosis. The local effect of RFA on the hepatic artery was similar. With intact portal blood flow during RFA, complete ablation of liver tissue around the pedicle was demonstrated by histochemical staining and measurement of the intracellular ATP concentration. CONCLUSION: RFA was safe when applied close to the main portal vein branch without a Pringle manoeuvre, with complete cellular destruction. Use of the Pringle manoeuvre resulted in delayed portal vein and hepatic artery thrombosis and injury to the hepatic artery and bile duct.  相似文献   
109.
Liu CL  Fan ST  Lo CM  Wong Y  Ng IO  Lam CM  Poon RT  Wong J 《Annals of surgery》2004,239(2):194-201
OBJECTIVE: The aim of this study was to determine whether abdominal drainage is beneficial after elective hepatic resection in patients with underlying chronic liver diseases. SUMMARY BACKGROUND DATA: Traditionally, in patients with chronic liver diseases, an abdominal drainage catheter is routinely inserted after hepatic resection to drain ascitic fluid and to detect postoperative hemorrhage and bile leakage. However, the benefits of this surgical practice have not been evaluated prospectively. PATIENTS AND METHODS: Between January 1999 and March 2002, 104 patients who had underlying chronic liver diseases were prospectively randomized to have either closed suction abdominal drainage (drainage group, n = 52) or no drainage (nondrainage group, n = 52) after elective hepatic resection. The operative outcomes of the 2 groups of patients were compared. RESULTS: Fifty-seven (55%) patients had major hepatic resection with resection of 3 Coiunaud's segments or more. Sixty-nine (66%) patients had liver cirrhosis and 35 (34%) had chronic hepatitis. Demographic, surgical, and pathologic details were similar between both groups. The primary indication for hepatic resection was hepatocellular carcinoma (n = 100, 96%). There was no difference in hospital mortality between the 2 groups of patients (drainage group, 6% vs. nondrainage group, 2%; P = 0.618). However, there was a significantly higher overall operative morbidity in the drainage group (73% vs. 38%, P < 0.001). This was related to a significantly higher incidence of wound complications in the drainage group compared with the nondrainage group (62% vs. 21%, P < 0.001). In addition, a trend toward a higher incidence of septic complications in the drainage group was observed (33% vs. 17%, P = 0.07). The mean (+/- standard error of mean) postoperative hospital stay of the drainage group was 19.0 +/- 2.2 days, which was significantly longer than that of the nondrainage group (12.5 +/- 1.1 days, P = 0.005). With a median follow-up of 15 months, none of the 51 patients with hepatocellular carcinoma in the drainage group developed metastasis at the drain sites. On multivariate analysis, abdominal drainage, underlying liver cirrhosis, major hepatic resection, and intraoperative blood loss of >1.5L were independent and significant factors associated with postoperative morbidity. CONCLUSION: Routine abdominal drainage after hepatic resection is contraindicated in patients with chronic liver diseases.  相似文献   
110.
Background and purpose: Quality of Life (QoL) studies have received a substantial amount of attention in medical and rehabilitative practices. However, there is still a paucity of studies in the area, especially on persons with brain injuries (BI). This pilot study, on the QoL of individuals with brain injuries in Hong Kong, attempts to fill this void. It is hoped that the finding of this study will guide the development of programmes and services to people with brain injuries.

Methods: Through the Self-help Group for People with Brain Damage in Hong Kong, 35 subjects (22 men and 13 women) were successfully recruited to participate in this study by convenience sampling. Demographic data were collected through face-to-face interviews guided by a questionnaire and QoL data were gathered using the Comprehensive Quality of Life Scale—Intellectual/Cognitive Disability—5th edition (ComQol-I5). The general emotional condition of the participants over the past 2 months was measured by a validated Chinese version of the Positive and Negative Affect Scale (PANAS). The participants' ratings on the importance of and their satisfaction with 20 health services areas were also collected.

Results: Preliminary results show that the overall mean quality of life score, as measured by ComQol-I5, was slightly less than two-thirds of the maximum score. Among the seven QoL domains, health and safety received some of the highest scores, while the lowest scores were obtained in the area of material well-being, place in community and productivity. People whose injuries had occurred relatively recently (less than 5 years ago) were found to have higher intimacy QoL scores than their counterparts injured more than 5 years ago. In the domain of safety, persons with a brain injury who were employed scored significantly higher than those who were not. Positive affect scores and the total affect of PANAS scores correlated significantly with the overall QoL scores. Moreover, persons with a brain injury usually felt satisfied with the services they valued as important. The top five most important services were medical services, occupational therapy, physiotherapy, vocational counselling and social work.

Discussion and conclusion: The QoL profile of people with brain injuries in Hong Kong was initially obtained and low scores in the ComQoL were identified in the domains of material well-being, community activities and responsibility and productivity. These might be the consequences of their physical and cognitive limitations due to brain injury. This implies that appropriate interventions to improve their daily life conditions and their social integration would be necessary to improve their QoL. On the other hand, the BI sample also rated relatively high scores in other ComQoL areas such as safety and health, reflecting a good living environment and probably good health care services. Those whose brain injuries had occurred less than 5 years ago tended to have a higher ComQoL intimacy score than those whose injuries occurred more than 5 years ago. In other words, their social relationships may deteriorate with the longer period post-injury so that this group may need more supportive services. In the safety domain, it was found that subjects who were employed after their brain injury scored significantly higher than those who were not, which matched studies about the significant contribution of work towards life satisfaction. The satisfaction of their needs in the services they received, which may affect their QoL, was also investigated. It is clear that they valued the medical and rehabilitation services they received and felt satisfied with them.  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