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   3782篇
  免费   237篇
  国内免费   10篇
耳鼻咽喉   42篇
儿科学   103篇
妇产科学   41篇
基础医学   707篇
口腔科学   57篇
临床医学   350篇
内科学   801篇
皮肤病学   43篇
神经病学   362篇
特种医学   97篇
外科学   531篇
综合类   69篇
一般理论   30篇
预防医学   323篇
眼科学   34篇
药学   219篇
中国医学   1篇
肿瘤学   219篇
  2022年   22篇
  2021年   36篇
  2020年   30篇
  2019年   43篇
  2018年   57篇
  2017年   57篇
  2016年   60篇
  2015年   56篇
  2014年   77篇
  2013年   118篇
  2012年   152篇
  2011年   175篇
  2010年   107篇
  2009年   102篇
  2008年   200篇
  2007年   187篇
  2006年   191篇
  2005年   179篇
  2004年   166篇
  2003年   163篇
  2002年   179篇
  2001年   89篇
  2000年   95篇
  1999年   78篇
  1998年   59篇
  1997年   62篇
  1996年   53篇
  1995年   46篇
  1994年   37篇
  1993年   30篇
  1992年   63篇
  1991年   98篇
  1990年   60篇
  1989年   63篇
  1988年   53篇
  1987年   69篇
  1986年   67篇
  1985年   63篇
  1984年   58篇
  1983年   50篇
  1982年   60篇
  1981年   32篇
  1979年   40篇
  1978年   25篇
  1977年   22篇
  1975年   27篇
  1974年   29篇
  1972年   23篇
  1971年   32篇
  1969年   21篇
排序方式: 共有4029条查询结果,搜索用时 15 毫秒
41.
OBJECTIVE: To determine whether blocking the cell surface expression of intracellular adhesion molecules (ICAM-1) in established severe acute pancreatitis (AP) would ameliorate pulmonary injury. SUMMARY BACKGROUND DATA: Lung injury in AP is in part mediated by infiltrating leukocytes, which are directed to lung tissue by ICAM-l. The authors' laboratory has previously demonstrated that AP results in overproduction of inflammatory cytokines, upregulation of pulmonary ICAM-1 expression, and a concomitant infiltration of neutrophils, which results in lung injury. METHODS: Young female mice were fed a choline-deficient/ethionine-supplemented diet to induce AP and were treated with a blocking dose of monoclonal antibody specific to the ICAM-1 receptor. Antibody treatment was administered at 72, 96, and 120 hours after beginning the diet, and all animals were killed at 144 hours. The degree of pancreatitis was evaluated by serum biochemical and tumor necrosis factor alpha levels as well as histology. The dual radiolabeled monoclonal antibody method was used to quantitate ICAM-1 cell surface expression in pulmonary tissue. Lung injury was assessed histologically and by determining lung microvascular permeability by measuring accumulated 125I-radiolabeled albumin. Pulmonary neutrophil sequestration was determined by the myeloperoxidase assay. RESULTS: All mice developed severe AP, and pancreatic injury was equally severe in both treated and untreated groups. Pulmonary ICAM-1 expression was significantly upregulated in animals with AP compared with controls. Treatment with a blocking dose of anti-ICAM-1 antibody after the induction of AP resulted in inhibited ICAM-1 cell surface expression to near control levels. Compared to untreated animals with AP, mice treated with anti-ICAM-1 mice had significantly reduced histologic lung injury and neutrophil sequestration, and a decreased microvascular permeability by more than twofold. CONCLUSIONS: These results demonstrate for the first time that treatment targeting the cell surface expression of ICAM-1 after the induction of AP ameliorates pulmonary injury, even in the face of severe pancreatic disease.  相似文献   
42.
AIM: To investigate patients' psychological distress in relation to memory and stressful experiences in the intensive care unit (ICU), and to identify early predictors for the development of high levels of acute post-traumatic stress disorder (PTSD)-related symptoms. METHODS: A prospective cohort study was performed over 18 months in two general ICUs, including 313 intubated mechanically ventilated adults admitted for more than 24 h, 226 of whom completed the study. Patients were interviewed 5 days and 2 months post-ICU concerning their memories and psychological distress. The instruments used were the ICU Memory Tool, ICU Stressful Experience Questionnaire, Hospital Anxiety and Depression Scale and Impact of Event Scale-Revised (IES-R). RESULTS: High symptom levels of anxiety, depression and acute PTSD 2 months post-ICU were present in 4.9%, 7.5% and 8.4% of the 226 patients, respectively. Psychological distress 2 months post-ICU was associated with experiences of the ICU rated as extremely stressful and with high levels of anxiety and depression 5 days post-ICU, but not with amnesia or delusional memories without factual recall of the ICU. Female sex, signs of agitation (increasing proportion of Motor Activity Assessment Scale scores of 4-6) and feelings of extreme fear during the ICU stay were significantly and independently associated with IES-R scores of 30 or more. CONCLUSIONS: Extremely stressful experiences of the ICU are associated with subsequent psychological distress. Female sex, agitation and extreme fear during the ICU stay seem to increase the risk of developing high levels of acute PTSD-related symptoms.  相似文献   
43.
OBJECTIVES: To compare a colonic J-pouch or a side-to-end anastomosis after low-anterior resection for rectal cancer with regard to functional and surgical outcome. SUMMARY BACKGROUND DATA: A complication after restorative rectal surgery with a straight anastomosis is low-anterior resection syndrome with a postoperatively deteriorated anorectal function. The colonic J-reservoir is sometimes used with the purpose of reducing these symptoms. An alternative method is to use a simple side-to-end anastomosis. METHODS: One-hundred patients with rectal cancer undergoing total mesorectal excision and colo-anal anastomosis were randomized to receive either a colonic pouch or a side-to-end anastomosis using the descending colon. Surgical results and complications were recorded. Patients were followed with a functional evaluation at 6 and 12 months postoperatively. RESULTS: Fifty patients were randomized to each group. Patient characteristics in both groups were very similar regarding age, gender, tumor level, and Dukes' stages. A large proportion of the patients received short-term preoperative radiotherapy (78%). There was no significant difference in surgical outcome between the 2 techniques with respect to anastomotic height (4 cm), perioperative blood loss (500 ml), hospital stay (11 days), postoperative complications, reoperations or pelvic sepsis rates. Comparing functional results in the 2 study groups, only the ability to evacuate the bowel in <15 minutes at 6 months reached a significant difference in favor of the pouch procedure. CONCLUSIONS: The data from this study show that either a colonic J-pouch or a side-to-end anastomosis performed on the descending colon in low-anterior resection with total mesorectal excision are methods that can be used with similar expected functional and surgical results.  相似文献   
44.
We sought an animal model able to discriminate metabolic and angiogenic processes in limb ischemia. For that we modified and evaluated a rat model of severe unilateral limb ischemia at rest. A two-stage surgical procedure entailing left femoral artery ligation preceded by interruption of collateral vessels originating from the infra-renal aorta and left iliac arteries was performed in Sprague-Dawley rats. The model was evaluated for up to 8 weeks with a transit-time flow meter, a laser Doppler perfusion imager, microspheres, arteriography and histology. It was found to be well tolerated with low mortality and perfusion in the foot skin was reduced up to 8 weeks, while collaterals were visible after 2 weeks. Histologic signs of ischemia were seen for up to 4 weeks. This rat model of severe limb ischemia at rest lasts up to 8 weeks and seems well suited for longitudinal studies of the pathophysiology of limb ischemia and healing mechanisms like angio- and arteriogenesis.  相似文献   
45.
46.
Sexual dysfunction after anterior lumbar fusion has mainly been focused on male biological function (retrograde ejaculation). The aim of the present study is to assess the effect of fusion surgery for chronic low back pain on the sex-related quality of life. Apart from routine prospective questionnaires, additional gender-specific mailed questionnaires produced retrospective data on sexual enjoyment and function after 2 years of follow-up. Patients randomised to non-surgical treatment and anterior or posterior fusion were compared. We found that surgically treated patients had a significantly better sex life than those non-surgically treated. The improved sex life was significantly associated with the reduced back pain. The improvement after anterior fusion, however, was counteracted by a trend towards disturbed orgasm and genital sensation in women, and a significant disturbance of ejaculation and genital sensation in men. In view of the increased frequency of anterior lumbar surgery with the strong promotion of disc replacement, the findings in the present small retrospective pilot study should be tested in larger prospective trials.  相似文献   
47.

Background

It is not known if the loads and motions reported for instrumented knees are generalizable to a larger population of total knee arthroplasty (TKA) patients. The purpose of this study is to (1) report axial implant force data for chair and stair activities for a population of cruciate-retaining TKA patients and (2) compare the population forces to those measured with instrumented TKAs.

Methods

Twenty-three subjects with a cruciate-retaining TKA underwent motion analysis during stair ascending, stair descending, chair sitting, and chair rising activities after informed consent in this institutional review board approved study. Axial TKA forces were calculated using a previously validated computational model. Differences between the mean and variability of population instrumented TKA peak forces and force impulses were tested using t tests and Levene test.

Results

Peak axial forces were 3.06, 2.74, 2.65, and 2.60 kN for stair ascent, stair descent, chair rising, and chair sitting, respectively. Force impulses were 123.3, 123.4, 153.5, and 154.0 kN*% activity cycle for stair ascent, stair descent, chair sitting, and chair rising, respectively. Population TKA and instrumented TKA peak forces were different for stair ascent (P = .03) and stair descent (P = .03) in the second half of the activity cycles. The variability of the peak forces and impulses were not different (P = .106 to P = .99).

Conclusion

The forces and motions presented in this study represent cruciate-retaining TKA patients and could be used for displacement-driven knee wear testing. The forces are similar to those in the literature from instrumented prostheses of an ultracongruent cruciate-sacrificing TKA.  相似文献   
48.
There are strong indications that only a small fraction of grafts successfully engraft in clinical islet transplantation. One explanation may be the instant blood-mediated inflammatory reaction (IBMIR) elicited by tissue factor, which is produced by the endocrine cells. In the present study, we show that islets intended for islet transplantation produce tissue factor in both the transmembrane and the alternatively spliced form and that the membrane-bound form is released as microparticles often associated with both insulin and glucagon granules. A low-molecular mass factor VIIa (FVIIa) inhibitor that indirectly blocks both forms of tissue factor was shown in vitro to be a promising drug to eliminate the IBMIR. Thrombin-antithrombin complex (TAT) and FVIIa-antithrombin complex (FVIIa-AT) were measured in nine patients who together received 20 infusions of isolated human islets. Both the TAT and FVIIa-AT complexes increased rapidly within 15-60 min after infusion. When the initial TAT and FVIIa-AT levels were plotted against the increase in C-peptide concentration after 7 days, patients with an initially strong IBMIR showed no significant increase in insulin synthesis after 7 days. In conclusion, tissue factor present in both the islets and the culture medium and elicits IBMIR, which affects the function of the transplanted islets.  相似文献   
49.
Background and purpose In recent years several different plate designs for internal fixation of fractures of the distal radius have been developed. However, few biomechanical studies have been performed to compare these new implants. The purpose of this study was to compare the mechanical properties of 5 different commercially available plates (3 volar and 2 dorsal) with standard K-wire fixation using a distal radial cadaver model.Material and methods 42 human radial bones from 26 cadavers were included. The bone mineral density (BMD) was measured by DEXA in all bones, and the radial bones were assigned to 6 equiv alent groups based on bone density and total amount of mineral. A distal radial osteotomy was done and a dorsal 30-degree wedge of bone was removed. 1 K-wire fixation group and 5 plate groups were tested for rigidity, yield load, and maximum load.Results When data from dorsally and volarly applied plates were pooled, we did not find any statistically significant differences between them regarding stiffness, yield load, and maximum load. The K-wire group showed significantly lower yield load than 3 of the plate groups. There were no statistically significant differences in yield load between the 5 plate groups. The K-wire group showed lower rigidity than the plate groups. The K-wire group and 1 plate group failed at a statistically significant lower maximum load than the 4 other plate groups.Interpretation The volar plates had the same mechanical stability as the dorsally applied plates, and they are therefore a good alternative to dorsally applied plates. K-wire osteosynthesis was inferior to plate osteosyntheses regarding all mechanical properties.  相似文献   
50.
Background: Breast reconstruction is a common standard procedure in many centres after breast cancer surgery. The aim of the present study was to investigate and compare the incidence of various complications in different reconstruction methods. Method: Six hundred and eighty-five patients were retrospectively classified into five groups: (1) Deep inferior epigastric perforator flap (DIEP), (2) latissimus dorsi flap (LD), (3) lateral thoracodorsal flap (LTDF), (4) expander with secondary implant (EXP), and (5) direct implant (DI). Demographic and perioperative data, the incidence of complications, and follow-up data were collected. Results: There was a significant difference between groups regarding overall early complications (p?<?0.001). The DIEP group had the highest incidence of overall complications (50.0%) (p?<?0.05). DIEP also had the highest incidence of fat necrosis (18.3%), skin necrosis (22.1%), and incidence of reoperation for complications (26.9%) compared to the other reconstruction methods. In the entire group of patients, the overall incidence of late complications (occurring >30 days after surgery) that needed surgical corrections was 54.7%. The incidence of late complications was 46.2% for DIEP, 66.4% for LD, 74.8% for LTDF, 44.9% for EXP, and 62.9% for DI. The DIEP group had higher incidences of late local complications (fat necrosis, skin necrosis, haematoma, seroma, and wound rupture combined), and scars requiring treatment than the other reconstruction methods. Conclusion: Meticulous registration of incidence of different complications in five different breast reconstruction methods revealed high complication rates with all methods. The differences in incidence of complications were related to the operation method used. Based on these results, careful individual planning of a breast reconstruction is mandatory.  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