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   5460篇
  免费   309篇
  国内免费   31篇
耳鼻咽喉   54篇
儿科学   218篇
妇产科学   80篇
基础医学   445篇
口腔科学   148篇
临床医学   629篇
内科学   1475篇
皮肤病学   67篇
神经病学   240篇
特种医学   126篇
外科学   1079篇
综合类   84篇
一般理论   1篇
预防医学   350篇
眼科学   136篇
药学   360篇
中国医学   27篇
肿瘤学   281篇
  2023年   40篇
  2022年   97篇
  2021年   188篇
  2020年   93篇
  2019年   149篇
  2018年   220篇
  2017年   128篇
  2016年   153篇
  2015年   149篇
  2014年   306篇
  2013年   305篇
  2012年   471篇
  2011年   508篇
  2010年   282篇
  2009年   212篇
  2008年   342篇
  2007年   339篇
  2006年   330篇
  2005年   246篇
  2004年   263篇
  2003年   219篇
  2002年   244篇
  2001年   44篇
  2000年   21篇
  1999年   46篇
  1998年   34篇
  1997年   36篇
  1996年   33篇
  1995年   21篇
  1994年   21篇
  1993年   15篇
  1992年   14篇
  1991年   10篇
  1990年   15篇
  1989年   19篇
  1988年   11篇
  1987年   11篇
  1986年   9篇
  1985年   21篇
  1984年   12篇
  1983年   7篇
  1982年   10篇
  1981年   12篇
  1980年   18篇
  1979年   8篇
  1978年   6篇
  1977年   6篇
  1976年   8篇
  1971年   7篇
  1970年   5篇
排序方式: 共有5800条查询结果,搜索用时 15 毫秒
51.
PURPOSE: The surgical resident experience with trauma has changed. Many residents are exposed to predominantly nonoperative patient care experiences while on trauma rotations. Data from a large multicenter study were analyzed to estimate surgical resident exposure to trauma laparotomy, diagnostic peritoneal lavage (DPL), and focused abdominal sonography for trauma (U/S). METHODS: Centers completed a self-report questionnaire on their institutional demographics, admissions, and procedure for a 2-year period (1998-1999). RESULTS: A total of 82 trauma centers that provide resident teaching were included. The included centers represent over 247,000 trauma admissions. The majority of trauma centers (65.9%) had > 80% blunt injury. Although all centers performed laparotomies, other results were more variable. For U/S, 24.2% performed none at all and 47.0% performed fewer than two U/S examinations per month. For DPLs, 3.8% performed none and 66.7% performed fewer than two per month. Assuming 1 night of 4 on call, the average surgical resident training at a trauma center performing > 80% blunt trauma has the potential to participate in only 15 trauma laparotomies, 6 diagnostic peritoneal lavages, and 45 ultrasound examinations per year. In addition, the resident will care for an average of 500 blunt trauma patients before performing a splenectomy or liver repair. CONCLUSION: Surgical resident experience on most trauma services is heavily weighted to nonoperative management, with a relatively low number of procedures, little experience with DPL, and highly variable experience with ultrasound. These data have serious implications for resident training and recruitment into the specialty.  相似文献   
52.
The purpose of the current study was to compare retrospectively the results of the Insall-Burstein constrained condylar knee implant used with and without intramedullary stems in 207 revision knee arthroplasties with the Insall-Burstein constrained condylar knee implant. One hundred sixty-one knees had either one or two stems placed. One hundred eight femoral stems and 76 tibial stems were placed. Fifty-five knees had no femoral or tibial stem. The average knee scores ranged from 52 preoperatively to 86 postoperatively. The average range of motion postoperatively was 4 degrees (range, 0 degrees -10 degrees ) to 106 degrees (range, 94 degrees -118 degrees ) in this group. The average postoperative knee score was 86 in the unstemmed group and 85 in the stemmed group with no difference in average range of motion. There were four (3%) cases of tibial loosening and two (2%) cases of femoral loosening in the unstemmed group. There were two (2%) cases of tibial loosening and two (2%) cases of femoral loosening at an average followup of 4.2 years (range, 2-6.2 years). Despite the higher constraint inherently designed in an Insall-Burstein constrained condylar knee component, the current study did not show a significantly higher loosening in implants without stems compared with implants used with stems. Therefore, the use of a semiconstrained component does not alone constitute a requirement for the use of an intramedullary stem.  相似文献   
53.
We have recently shown that HPV-positive tonsillar carcinoma in young patients exhibits nonkeratinizing basaloid morphology and a characteristic immunophenotype. The purpose of this study was to review a large number of cases of oropharyngeal carcinomas, in all age groups, and to identify tumors with nonkeratinizing morphology. Using polymerase chain reaction (PCR) the prevalence and type of HPV DNA was determined in representative cases and in a control group of conventional keratinizing squamous cell carcinomas. The tumors were further characterized with a panel of immunohistochemical stains. A total of 235 carcinomas were reviewed; 141 of the tonsils and 94 in the base of tongue. Ninety (36%) of the tonsillar and 30 (32%) of the base of tongue carcinomas were nonkeratinizing (NKCa) with basal cell features; the rest were classical keratinizing squamous cell carcinomas (KSCC). HPV DNA, particularly type 16, was identified in 10 (100%) of 10 of NKCA and in only 2 (20%) of 10 of KSCC (P = .0014). NKCas were strongly reactive to p16 antibodies while KSCC showed weak and focal reactivity. Higher Ki67 and lower p53 staining scores were observed in NKCa as compared to KSCC. It is concluded that NKCa of the tonsils and base of tongue is a distinct subtype of squamous cell carcinoma of the head and neck with high prevalence of HPV DNA and a characteristic immunophenotype.  相似文献   
54.
Robot assisted laparoscopic partial nephrectomy: initial experience   总被引:10,自引:0,他引:10  
PURPOSE: Advances in laparoscopy have made laparoscopic partial nephrectomy a technically feasible procedure but it remains challenging to even experienced laparoscopists. We hypothesized that robotic assisted laparoscopic partial nephrectomy may make this procedure more efficacious than the standard laparoscopic approach. MATERIALS AND METHODS: Ten patients with a mean age of 58 years and mean tumor size of 2.0 cm underwent robotic assisted laparoscopic partial nephrectomy and another 10 with a mean age of 61 years and mean tumor size of 2.18 cm underwent laparoscopic partial nephrectomy, as performed by a team of 2 surgeons (MS and ST) between May 2002 and January 2004. Demographic data, intraoperative parameters and postoperative data were compared between the 2 groups. RESULTS: There were no significant differences in patient demographics between the 2 groups. Intraoperative data and postoperative outcomes were statistically similar. In the 10 patients who underwent robotic assisted laparoscopic partial nephrectomy there were 2 intraoperative complications. There was 1 conversion in the laparoscopic partial nephrectomy group. CONCLUSIONS: Robotic assisted laparoscopic partial nephrectomy is a safe and feasible procedure in patients with small exophytic masses. The robotic approach to laparoscopic partial nephrectomy does not offer any clinical advantage over conventional laparoscopic nephrectomy.  相似文献   
55.

OBJECTIVE

To explore the ability of a novel transrectal ultrasonography (TRUS) device (TargetScanTM, Envisioneering Medical Technologies, St. Louis MO) that creates a three‐dimensional map of the prostate and calculates an optimal biopsy scheme, to accurately sample the prostate and define the true extent of disease, as standard TRUS‐guided prostate biopsy relies on the operator to distribute the biopsy sites, often resulting in under‐ and oversampling regions of the gland.

PATIENTS AND METHODS

In a multicentre retrospective chart review evaluating patients who had a TargetScan prostate biopsy between January 2006 and June 2007, we determined the overall cancer detection rate in all patients and in subgroups based on prostate specific antigen level, digital rectal examination, and indication for biopsy. We assessed the pathological significance of cancer detected, defined as a Gleason score of ≥7, positive margins, extracapsular disease or >20% tumour volume in the prostatectomy specimen. We also evaluated the concordance in Gleason score between the biopsy and prostatectomy specimen.

RESULTS

Cancer was detected in 50 (35.7%) of the 140 patients biopsied, including 39 (47.6%) with no previous biopsies. Of 23 prostatectomy specimens, 20 (87%) had pathologically significant disease. The biopsy predicted the prostatectomy Gleason score in 12 patients (52%), overestimated in two (9%), underestimated in eight (35%), and biopsy Gleason score could not be assigned in one (4%).

CONCLUSIONS

Template‐guided biopsy potentially produces a higher cancer detection rate and more accurate assessment of grade. Prostatectomy specimens did not have a high rate of pathologically insignificant disease.  相似文献   
56.
57.
58.

Background

Despite significant advantages to patients, less than 5% of all colorectal surgeries for cancer are performed laparoscopically. A minimally invasive colorectal cancer program was created in our Veterans' Affairs hospital with the intent of increasing access and improving quality of patient care while maintaining patient safety and oncologic standards.

Methods

Sixty consecutive laparoscopic colorectal cancer resections and 60 age-matched open resections were identified. Our prospective database was queried for demographic, clinical outcomes, and oncologic data.

Results

Patients undergoing laparoscopic resections experienced a shorter hospital stay and a quicker return of bowel function. Both groups had similar intraoperative blood loss and surgical times. Laparoscopic resections achieved equivalent lymph node retrieval and resection completeness compared with open resections. Laparoscopic resections resulted in fewer wounds and fewer complications requiring reoperation.

Conclusions

Establishment of a minimally invasive colorectal cancer program in a Veterans Affairs Medical Center leads to increased access to laparoscopic colorectal resections and improved patient care while maintaining patient safety.  相似文献   
59.
60.
Genetic, biochemical and physiological studies have demonstrated that the renin-angiotensin system (RAS) plays a fundamental role in kidney development. All of the components of the RAS are expressed in the metanephros. Mutations in the genes encoding components of the RAS in mice or pharmacological inhibition of RAS in animals or humans cause diverse congenital abnormalities of the kidney and lower urinary tract. The latter include renal vascular abnormalities, abnormal glomerulogenesis, renal papillary hypoplasia, hydronephrosis, aberrant UB budding, duplicated collecting system, and urinary concentrating defect. Thus, the actions of angiotensin (ANG) II during kidney development are pleiotropic both spatially and temporally. Whereas the role of ANG II in renovascular and glomerular development has received much attention, little is known about the potential role of ANG II and its receptors in the morphogenesis of the collecting system. In this review, we discuss recent genetic and functional evidence gathered from transgenic knockout mice and in vitro organ and cell culture implicating the RAS in the development of the ureteric bud and collecting ducts. A novel conceptual framework has emerged from this body of work which states that stroma-derived ANG II elicits activation of AT1/AT2 receptors expressed on the ureteric bud to stimulate branching morphogenesis as well as collecting duct elongation and papillogenesis.  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