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   284篇
  免费   18篇
儿科学   10篇
基础医学   43篇
口腔科学   14篇
临床医学   29篇
内科学   36篇
皮肤病学   3篇
神经病学   15篇
特种医学   19篇
外科学   42篇
综合类   36篇
预防医学   15篇
眼科学   5篇
药学   3篇
肿瘤学   32篇
  2023年   3篇
  2022年   3篇
  2021年   7篇
  2020年   3篇
  2019年   3篇
  2018年   4篇
  2017年   5篇
  2016年   4篇
  2015年   5篇
  2014年   13篇
  2013年   12篇
  2012年   14篇
  2011年   10篇
  2010年   21篇
  2009年   13篇
  2008年   13篇
  2007年   11篇
  2006年   11篇
  2005年   17篇
  2004年   4篇
  2003年   5篇
  2002年   3篇
  2001年   8篇
  2000年   2篇
  1999年   7篇
  1998年   12篇
  1997年   7篇
  1996年   5篇
  1995年   5篇
  1994年   10篇
  1993年   6篇
  1992年   2篇
  1991年   3篇
  1990年   5篇
  1989年   5篇
  1988年   9篇
  1987年   3篇
  1986年   2篇
  1985年   3篇
  1984年   5篇
  1981年   2篇
  1980年   7篇
  1977年   2篇
  1976年   3篇
  1974年   1篇
  1973年   1篇
  1970年   1篇
  1969年   1篇
  1966年   1篇
排序方式: 共有302条查询结果,搜索用时 15 毫秒
1.
The authors reviewed their institutional experience with liver resection for metastatic colorectal carcinoma to (1) determine whether perioperative blood transfusion affects survival; (2) identify prognostic determinants; and (3) estimate the patient requirement for a prospective randomized trial designed to demonstrate efficacy of liver resection. Two hundred eighty consecutive patients treated by potentially curative liver resection between 1960 and 1987 were included. Data were obtained for all but 10 patients for at least 5 years after operation or through 1990. Actuarial survival curves related to potential prognostic determinants were analyzed with the log-rank test. Overall, survival was 47 +/- 3% at 3 years and 25 +/- 3% at 5 years, including 4% 60-day operative mortality rate. Eighty-one patients who did not receive blood 7 days before to 14 days after operation had 60 +/- 6% 3-year and 32 +/- 6% 5-year survival compared with 40 +/- 4% and 21 +/- 3% survival rates for 183 patients who received at least one unit (p = 0.03, operative deaths excluded). Extrahepatic disease (p = 0.015), extrahepatic lymph node involvement (p = 0.002), satellite configuration of multiple metastases (p = 0.0052), and initial detection by abnormal liver enzymes (p = 0.0005) were associated with poor survival rates. Synchronous presentation of metastatic and stage B primary disease was associated with a favorable prognosis (p = 0.003). The requirement for a prospective randomized trial estimated by an exponential survival model would be 36, 74, 168, or 428 patients if 5-year survival without resection were 1, 5, 10, or 15%. We conclude that (1) perioperative blood transfusion may be adversely associated with survival; (2) extrahepatic disease, extrahepatic lymph node involvement, satellite configuration, and initial detection by clinical examination or a liver enzyme abnormality portend a poor prognosis; and (3) a prospective randomized trial of liver resection is impractical because of the large patient requirement, at least by a single institution.  相似文献   
2.
Cardiac tissues show a propensity to develop nonbacterial thrombotic endocarditis, a meshwork of platelets and fibrin. This lesion may cause a predisposition to subsequent colonization by circulating microorganisms, leading to infective endocarditis. We measured platelet adherence in vitro to cultured endothelial cells derived from the porcine aortic valve and ascending aorta. We found that valvular endothelial cells showed a twofold to threefold higher adherence than ascending aortic endothelial cells of chromium 51-labeled platelets in the presence of proteolytically active thrombin. This finding did not correlate with endothelial prostacyclin release: cardiac valve endothelial cells released more prostacyclin than did, ascending aortic cells, exogenous prostacyclin had no effect on thrombin-stimulated adherence, and aspirin inhibition of endothelial prostacyclin synthesis showed no effect on platelet adherence. Fixation of platelets abolished thrombin-stimulated adherence; fixation of endothelial cells had minimal effect. We suggest that these differences may contribute to the propensity of the cardiac valve to develop nonbacterial thrombotic endocarditis.  相似文献   
3.
Renal transplant (RT) is now a therapy of choice for end stage renal disease (ESRD). The Nephrology Unit, Asvini started functioning in Dec 90 and to date 1298 sittings of hemodialysis have been given to 45 patients. Of these, 35 were in ESRD and 11 patients underwent renal transplantation at this hospital during the period Jan 91 – Dec 93. One patient expired after 18 months of transplantation due to infection. Early experience in screening patients for RT, use of immunosuppression, management of rejection episodes and protocol are presented with special emphasis on its relevance to the Armed Forces.KEY WORDS: Transplantation, Renal Failure, Immunosuppression, Rejection  相似文献   
4.
This study examined the linkage of posttraumatic growth (PTG) to quality of life (QOL) among individuals newly diagnosed with cancer. Individuals (26 men, 36 women) reported PTG 3 months postdiagnosis (T1) and 3 months later (T2). Cross‐sectional analyses revealed a linear association between PTG and QOL—more PTG was related to worse mental health at T1 (β = ?.28). PTG, however, revealed a quadratic relationship with depressive symptoms at T1 and physical health at T2: Individuals with high or low levels of PTG had fewer depressive symptoms and better QOL than those with moderate levels. Longitudinal analyses revealed a linear association between PTG and QOL; more PTG at T1 predicted better physical health at T2. There were no longitudinal curvilinear associations. Although the linear links of PTG to QOL were contradictory within this study, both of the curvilinear relations, although not robust, confirm previous research. Further analyses differentiated low, medium, and high PTG groups in terms of perceiving cancer as stressful, intrusive thoughts, and coping strategies. Overall, relations of PTG to adjustment may be more complex and dynamic than previously assumed. Clinicians should consider the notion that more growth may sometimes, but not always, be better.  相似文献   
5.
Background contextThere is currently no reliable technique for intraoperative assessment of pedicle screw fixation strength and optimal screw size. Several studies have evaluated pedicle screw insertional torque (IT) and its direct correlation with pullout strength. However, there is limited clinical application with pedicle screw IT as it must be measured during screw placement and rarely causes the spine surgeon to change screw size. To date, no study has evaluated tapping IT, which precedes screw insertion, and its ability to predict pedicle screw pullout strength.PurposeThe objective of this study was to investigate tapping IT and its ability to predict pedicle screw pullout strength and optimal screw size.Study designIn vitro human cadaveric biomechanical analysis.MethodsTwenty fresh-frozen human cadaveric thoracic vertebral levels were prepared and dual-energy radiographic absorptiometry scanned for bone mineral density (BMD). All specimens were osteoporotic with a mean BMD of 0.60±0.07 g/cm2. Five specimens (n=10) were used to perform a pilot study, as there were no previously established values for optimal tapping IT. Each pedicle during the pilot study was measured using a digital caliper as well as computed tomography measurements, and the optimal screw size was determined to be equal to or the first size smaller than the pedicle diameter. The optimal tap size was then selected as the tap diameter 1 mm smaller than the optimal screw size. During optimal tap size insertion, all peak tapping IT values were found to be between 2 in-lbs and 3 in-lbs. Therefore, the threshold tapping IT value for optimal pedicle screw and tap size was determined to be 2.5 in-lbs, and a comparison tapping IT value of 1.5 in-lbs was selected. Next, 15 test specimens (n=30) were measured with digital calipers, probed, tapped, and instrumented using a paired comparison between the two threshold tapping IT values (Group 1: 1.5 in-lbs; Group 2: 2.5 in-lbs), randomly assigned to the left or right pedicle on each specimen. Each pedicle was incrementally tapped to increasing size (3.75, 4.00, 4.50, and 5.50 mm) until the threshold value was reached based on the assigned group. Pedicle screw size was determined by adding 1 mm to the tap size that crossed the threshold torque value. Torque measurements were recorded with each revolution during tap and pedicle screw insertion. Each specimen was then individually potted and pedicle screws pulled out “in-line” with the screw axis at a rate of 0.25 mm/sec. Peak pullout strength (POS) was measured in Newtons (N).ResultsThe peak tapping IT was significantly increased (50%) in Group 2 (3.23±0.65 in-lbs) compared with Group 1 (2.15±0.56 in-lbs) (p=.0005). The peak screw IT was also significantly increased (19%) in Group 2 (8.99±2.27 in-lbs) compared with Group 1 (7.52±2.96 in-lbs) (p=.02). The pedicle screw pullout strength was also significantly increased (23%) in Group 2 (877.9±235.2 N) compared with Group 1 (712.3±223.1 N) (p=.017). The mean pedicle screw diameter was significantly increased in Group 2 (5.70±1.05 mm) compared with Group 1 (5.00±0.80 mm) (p=.0002). There was also an increased rate of optimal pedicle screw size selection in Group 2 with 9 of 15 (60%) pedicle screws compared with Group 1 with 4 of 15 (26.7%) pedicle screws within 1 mm of the measured pedicle width. There was a moderate correlation for tapping IT with both screw IT (r=0.54; p=.002) and pedicle screw POS (r=0.55; p=.002).ConclusionsOur findings suggest that tapping IT directly correlates with pedicle screw IT, pedicle screw pullout strength, and optimal pedicle screw size. Therefore, tapping IT may be used during thoracic pedicle screw instrumentation as an adjunct to preoperative imaging and clinical experience to maximize fixation strength and optimize pedicle “fit and fill” with the largest screw possible. However, further prospective, in vivo studies are necessary to evaluate the intraoperative use of tapping IT to predict screw loosening/complications.  相似文献   
6.

Background

Nodding Syndrome is a seizure disorder of children in Mundri County, Western Equatoria, South Sudan. The disorder is reported to be spreading in South Sudan and northern Uganda.

Objective

To describe environmental, nutritional, infectious, and other factors that existed before and during the de novo 1991 appearance and subsequent increase in cases through 2001.

Methods

Household surveys, informant interviews, and case-control studies conducted in Lui town and Amadi village in 2001–2002 were supplemented in 2012 by informant interviews in Lui and Juba, South Sudan.

Results

Nodding Syndrome was associated with Onchocerca volvulus and Mansonella perstans infections, with food use of a variety of sorghum (serena) introduced as part of an emergency relief program, and was inversely associated with a history of measles infection. There was no evidence to suggest exposure to a manmade neurotoxic pollutant or chemical agent, other than chemically dressed seed intended for planting but used for food. Food use of cyanogenic plants was documented, and exposure to fungal contaminants could not be excluded.

Conclusion

Nodding Syndrome in South Sudan has an unknown etiology. Further research is recommended on the association of Nodding Syndrome with onchocerciasis/mansonelliasis and neurotoxins in plant materials used for food.  相似文献   
7.
Inflammation in areas of fibrosis (i‐IFTA) in posttransplant biopsy specimens has been associated with decreased death‐censored graft survival (DC‐GS). Additionally, an i‐IFTA score ≥ 2 is part of the diagnostic criteria for chronic active TCMR (CA TCMR). We examined the impact of i‐IFTA and t‐IFTA (tubulitis in areas of atrophy) in the first biopsy for cause after 90 days posttransplant (n = 598); mean (SD) 1.7 ± 1.4 years posttransplant. I‐IFTA, present in 196 biopsy specimens, was strongly correlated with t‐IFTA, and Banff i. Of the 196, 37 (18.9%) had a previous acute rejection episode; 96 (49%) had concurrent i score = 0. Unlike previous studies, i‐IFTA = 1 (vs 0) was associated with worse 3‐year DC‐GS: (i‐IFTA = 0, 81.7%, [95% CI 77.7 to 85.9%]); i‐IFTA = 1, 68.1%, [95% CI 59.7 to 77.6%]; i‐IFTA = 2, 56.1%, [95% CI 43.2 to 72.8%], i‐IFTA = 3, 48.5%, [95% CI 31.8 to 74.0%]). The association of i‐IFTA with decreased DC‐GS remained significant when adjusted for serum creatinine at the time of the biopsy, Banff i, ci and ct, C4d and DSA. T‐IFTA was similarly associated with decreased DC‐GS. Of these indication biopsies, those with i‐IFTA ≥ 2, without meeting other criteria for CA TCMR had similar postbiopsy DC‐GS as those with CA TCMR. Those with i‐IFTA = 1 and t ≥ 2, ti ≥ 2 had postbiopsy DC‐GS similar to CA TCMR. Biopsies with i‐IFTA = 1 had similar survival as CA TCMR when biopsy specimens also met Banff criteria for TCMR and/or AMR. Studies of i‐IFTA and t‐IFTA in additional cohorts, integrating analyses of Banff scores meeting criteria for other Banff diagnoses, are needed.  相似文献   
8.
9.
The transfer from pediatric to adult diabetes health care for emerging adults with type 1 diabetes (T1D) has received increasing attention in the literature. This review analyzes the effect of this health care transfer on the outcomes of diabetes care visit attendance, glycemic control, and acute diabetes‐related complications, and assesses the methodological strength of the studies reporting observational and interventional data. Observational studies, often limited by incomplete data, report a decline in diabetes care visits but an improvement or no change in hemoglobin A1c (HbA1c) after transfer to adult care. Results from studies reporting a transition intervention are restricted by lack of appropriate control groups and the collection of data both before and after transfer of care. Very few methodologically strong studies are available to guide clinicians with the transition from pediatric to adult care, and these shortcomings should be addressed in future studies designed to facilitate and improve the care of emerging adults with T1D.  相似文献   
10.
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