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   239篇
  免费   25篇
  国内免费   1篇
儿科学   16篇
妇产科学   6篇
基础医学   26篇
口腔科学   5篇
临床医学   16篇
内科学   61篇
皮肤病学   4篇
神经病学   7篇
特种医学   19篇
外科学   74篇
综合类   9篇
预防医学   13篇
药学   4篇
肿瘤学   5篇
  2023年   1篇
  2021年   2篇
  2019年   5篇
  2018年   36篇
  2017年   19篇
  2016年   10篇
  2015年   8篇
  2014年   10篇
  2013年   13篇
  2012年   10篇
  2011年   5篇
  2010年   11篇
  2009年   12篇
  2008年   9篇
  2007年   7篇
  2006年   10篇
  2005年   6篇
  2004年   2篇
  2003年   5篇
  2002年   5篇
  2001年   2篇
  2000年   2篇
  1999年   5篇
  1998年   12篇
  1997年   13篇
  1996年   4篇
  1995年   5篇
  1994年   4篇
  1993年   9篇
  1992年   2篇
  1989年   1篇
  1988年   1篇
  1987年   3篇
  1986年   4篇
  1985年   1篇
  1983年   2篇
  1981年   2篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1976年   1篇
  1970年   2篇
  1968年   1篇
排序方式: 共有265条查询结果,搜索用时 15 毫秒
71.
To identify the predictive factors for testicular sperm extraction (TESE) and to understand the pathology associated with TESE, we carried out a prospective study in 40 consecutive men with azoospermia due to primary gonadal failure. The main outcome measure was the retrieval of at least one testicular spermatozoon. Endocrine and biophysical profiles, testicular histology, Johnsen score and testicular spermatids were used as predictors of sperm extraction. Spermatogenesis was quantified with the Johnsen score. A variable pattern of spermatogenesis was common, being present in 20 (50%) patients. Visualisation of testicular spermatids on testicular histology showed a strong association with TESE (P < 0.0001). Statistically significant differences were detected in plasma follicle stimulating hormone (FSH) and testicular volume between patients who had hypospermatogenesis and Sertoli cell-only or maturation arrest. There were no significant differences in Johnsen score, biophysical and endocrine profiles between the groups with successful and failed TESE. However, a statistically significant trend occurred with changes in histological pattern [chi2 for trend, P = 0.001; Pearson's coefficient (r) = 0.6], Johnsen score (P = 0.022; r = 0.5), testicular volume (P = 0.01; r = 0.5) and plasma FSH concentrations (P = 0.044; r = 0.4), albeit to a limited degree. Difference in the interpretation of histological patterns with different assessors was observed. The type of occupation or risk factors for azoospermia showed no association with testicular pathology or TESE. Variable histological patterns in different tubules in the same individual may explain the poor correlation of TESE with endocrine and biophysical profiles, Johnsen score and histological pattern. Differences in the amount of tissue used for TESE and histopathology, and misinterpretation of testicular histology rather than failure to quantify spermatogenesis may explain the poor correlation between histological patterns and TESE. Testicular spermatids predicted TESE. However, considerable overlap in values means that no single variable can provide a perfect discrimination between the groups with successful and failed TESE.   相似文献   
72.
Two modes of embryo transfer, uterine and tubal, were compared following natural cycle in-vitro fertilization (IVF). Only patients with patent Fallopian tubes were included in the study. Tubal embryo transfer was performed by retrograde tubal cannulation without analgesia on an outpatient basis. Tubal transfer conferred no benefit compared with uterine transfer in male factor infertility with positive fertilization (pregnancy rates of 15.8% in both groups). Although tubal embryo transfer in the patients with unexplained infertility improved the pregnancy rates from 7.8% in uterine transfer (5/64) to 17.6% in the tubal transfer group (13/74), this improvement was not statistically significant.   相似文献   
73.
The relationship between modern clinical diagnostic data, such as from radiographs or computed tomography, and the temporal biomechanical integrity of bone fracture healing has not been well‐established. A diagnostic tool that could quantitatively describe the biomechanical stability of the fracture site in order to predict the course of healing would represent a paradigm shift in the way fracture healing is evaluated. This paper describes the development and evaluation of a wireless, biocompatible, implantable, microelectromechanical system (bioMEMS) sensor, and its implementation in a large animal (ovine) model, that utilized both normal and delayed healing variants. The in vivo data indicated that the bioMEMS sensor was capable of detecting statistically significant differences (p‐value <0.04) between the two fracture healing groups as early as 21 days post‐fracture. In addition, post‐sacrifice micro‐computed tomography, and histology data demonstrated that the two model variants represented significantly different fracture healing outcomes, providing explicit supporting evidence that the sensor has the ability to predict differential healing cascades. These data verify that the bioMEMS sensor can be used as a diagnostic tool for detecting the in vivo course of fracture healing in the acute post‐treatment period. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1439–1446, 2015.  相似文献   
74.
Informed consent for living donor liver transplantation (LDLT) requires that patients are provided with accurate information on the relative benefits and risks of this procedure compared with deceased donor liver transplantation (DDLT). There is strong evidence to suggest that LDLT facilitates timely transplantation to patients; however, information on the relative morbidity and death risks after LDLT as compared with DDLT is limited. A matched cohort comparison was performed matching recipients for age, MELD, date of transplant, gender, primary diagnosis, and recipient surgeon. A total of 145 LDLT were matched with 145 DDLT. LDLT had a higher overall rate of perioperative surgical complications (P = 0.009). Most of this difference was caused by a higher rate of biliary complications. However, the complications that occurred in the DDLT group tended to be more serious (P = 0.037), and these complications were strongly associated with graft loss in multivariate analysis. The 3‐ and 5‐year graft and patient survivals were similar. In conclusion, DDLT and LDLT have different complication profiles, but comparable hospital stays and survival rates. In areas of deceased donor organ shortages, LDLT offers an excellent alternative to DDLT because it facilitates access to a liver transplant without compromising short‐ or medium‐term recipient outcomes.  相似文献   
75.

Purpose

The purpose of this study is to clarify morphological changes of acetabular subchondral bone cyst after total hip arthroplasty for osteoarthritis secondary to developmental dysplasia of the hip.

Methods

Two hundred and sixty-one primary cementless total hip arthroplasties of 208 patients, 18 males, 190 females, were retrospectively reviewed. Morphological changes of subchondral bone cyst were evaluated by computed tomography (CT). The mean cross-sectional area of the cyst from CT scans at 3 months postoperatively and after 7–10 years (average 8.4 years) were compared.

Results

Acetabular subchondral bone cysts were found in 49.0% of all cases in preoperative CT scans. There was no cyst which was newly recognized in CT scan performed after postoperative 7–10 years. All the cross-sectional areas of the cysts evaluated in this study were reduced postoperatively.

Conclusions

This study revealed that acetabular subchondral bone cysts do not increase or expand after total hip arthroplasty and indicated that the longitudinal morphological change of acetabular bone cysts in patients of developmental dysplasia of the hip do not influence long-term implant fixation in total hip arthroplasty.
  相似文献   
76.

BACKGROUND CONTEXT

Screw loosening is a prevalent failure mode in orthopedic hardware, particularly in osteoporotic bone or revision procedures where the screw-bone engagement is limited.

PURPOSE

The objective of this study was to evaluate the efficacy of a novel screw retention technology (SRT) in an ovine lumbar fusion model.

STUDY DESIGN/SETTING

This was a biomechanical, radiographic, and histologic study utilizing an ovine lumbar spine model.

METHODS

: In total, 54 (n=54) sheep lumbar spines (L2–L3) underwent posterior lumbar fusion (PLF) via pedicle screw fixation, connecting rod, and bone graft. Following three experimental variants were investigated: positive control (ideal clinical scenario), negative control (simulation of compromised screw holes), and SRT treatments. Biomechanical and histologic analyses of the functional spinal unit (FSU) were determined as a function of healing time (0, 3, and 12 months postoperative).

RESULTS

Screw pull-out, screw break-out, and FSU stability of the SRT treatments were generally equivalent to the positive control group and considerably better than the negative control group. Histomorphology of the SRT treatment screw region of interest (ROI) observed an increase in bone percentage and decrease in void space during healing, consistent with ingrowth at the implant interface. The PLF ROI observed similar bone percentage throughout healing between the SRT treatment and positive control. Less bone formation was observed for the negative control.

CONCLUSIONS

The results of this study demonstrate that the SRT improved screw retention and afforded effective FSU stabilization to achieve solid fusion in an otherwise compromised fixation scenario in a large animal model.  相似文献   
77.

Background

Hepatitis B (HBV) and hepatitis C (HCV) are well-recognized risk factors for hepatocellular carcinoma (HCC). The characteristics and clinical outcomes of HCC arising from these conditions may differ. This study was conducted to compare the outcomes of HCC associated with HBV and HCV after liver resection.

Methods

Of 386 liver resections for HCC performed between July 1992 and April 2011, 181 patients had HBV and 74 patients had HCV. Patients with HBV/HCV coinfections (n = 20), non-HBV/HCV etiology (n = 94), and postoperative death within 3 months (n = 17) were excluded. Patient, tumor characteristics, and perioperative and oncologic outcomes were compared between patients with HBV and HCV.

Results

The patients with HBV had better overall survival (OS) than patients with HCV (68 vs. 59 months, p = 0.03); however, there was no difference in recurrence-free survival (RFS) between the groups (44 vs. 45 months, p = 0.1). The factors predictive of OS based on multivariate analyses included: vascular invasion [p < 0.01, hazard ratio (HR) = 3.4], Child-Pugh Score (p < 0.01, HR = 4.8), and underlying liver disease (HCV vs HBV) (p = 0.01, HR = 1.9). Vascular invasion and tumor number (p < 0.01, HR = 2.3 and p < 0.01, HR = 2.1) were independent predictors of RFS.

Conclusions

OS but not RFS after liver resection for HCC is better in patients with HBV than HCV. This survival advantage for HBV patients may be due to differences in tumor biology and outcomes after disease recurrence.  相似文献   
78.

Background Context

The most commonly used materials used for interbody cages are titanium metal and polymer polyetheretherketone (PEEK). Both of these materials have demonstrated good biocompatibility. A major disadvantage associated with solid titanium cages is their radiopacity, limiting the postoperative monitoring of spinal fusion via standard imaging modalities. However, PEEK is radiolucent, allowing for a temporal assessment of the fusion mass by clinicians. On the other hand, PEEK is hydrophobic, which can limit bony ingrowth. Although both PEEK and titanium have demonstrated clinical success in obtaining a solid spinal fusion, innovations are being developed to improve fusion rates and to create stronger constructs using hybrid additive manufacturing approaches by incorporating both materials into a single interbody device.

Purpose

The purpose of this study was to examine the interbody fusion characteristic of a PEEK Titanium Composite (PTC) cage for use in lumbar fusion.

Study Design/Setting

Thirty-four mature female sheep underwent two-level (L2–L3 and L4–L5) interbody fusion using either a PEEK or a PTC cage (one of each per animal). Animals were sacrificed at 0, 8, 12, and 18 weeks post surgery.

Materials and Methods

Post sacrifice, each surgically treated functional spinal unit underwent non-destructive kinematic testing, microcomputed tomography scanning, and histomorphometric analyses.

Results

Relative to the standard PEEK cages, the PTC constructs demonstrated significant reductions in ranges of motion and a significant increase in stiffness. These biomechanical findings were reinforced by the presence of significantly more bone at the fusion site as well as ingrowth into the porous end plates.

Conclusions

Overall, the results indicate that PTC interbody devices could potentially lead to a more robust intervertebral fusion relative to a standard PEEK device in a clinical setting.  相似文献   
79.
Biliary strictures remain the most challenging aspect of adult right lobe living donor liver transplantation (RLDLT). Between 04/2000 and 10/2005, 130 consecutive RLDLTs were performed in our center and followed prospectively. Median follow-up was 23 months (range 3-67) and 1-year graft and patient survival was 85% and 87%, respectively. Overall incidence of biliary leaks (n = 19) or strictures (n = 22) was 32% (41/128) in 33 patients (26%). A duct-to-duct (D-D) or Roux-en-Y (R-Y) anastomosis were performed equally (n = 64 each) with no difference in stricture rate (p = 0.31). The use of ductoplasty increased the number of grafts with a single duct for anastomosis and reduced the biliary complication rate compared to grafts >/=2 ducts (17% vs. 46%; p = 0.02). Independent risk factors for strictures included older donor age and previous history of a bile leak. All strictures were managed nonsurgically initially but four patients ultimately required conversion from D-D to R-Y. Ninety-six percent (123/128) of patients are currently free of any biliary complications. D-D anastomosis is safe after RLDLT and provides access for future endoscopic therapy in cases of leak or stricture. When presented with multiple bile ducts, ductoplasty should be considered to reduce the potential chance of stricture.  相似文献   
80.
Right lobe living donor liver transplantation (RLDLT) is not yet a fully accepted therapy for patients with end-stage liver failure in the Western hemisphere because of concerns about donor safety and inferior recipient outcomes. An outcome analysis from the time of listing for all adult patients who were listed for liver transplantation (LT) at our center was performed. From 2000 to 2006, 1091 patients were listed for LT. One hundred fifty-four patients (LRD; 14%) had suitable live donors and 153 (99%) underwent RLDLT. Of the remaining patients (DD/Waiting List; n = 937), 350 underwent deceased donor liver transplant (DDLT); 312 died or dropped off the waiting list; and 275 were still waiting at the time of this analysis. The LRD group had shorter mean waiting times (6.0 months vs. 9.8 months; p < 0.001). Although medical model for end-stage liver disease (MELD) scores were similar at the time of listing, MELD scores at LT were significantly higher in the DD/Waiting List group (15.4 vs. 19.5; p = 0.002). Patients in Group 1 had a survival advantage with RLDLT from the time of listing (1-year survival 90% vs. 80%; p < 0.001). To our knowledge, this is the first report to document a survival advantage at time of listing for RLDLT over DDLT.  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