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   729篇
  免费   27篇
  国内免费   5篇
耳鼻咽喉   3篇
儿科学   14篇
妇产科学   36篇
基础医学   86篇
口腔科学   9篇
临床医学   97篇
内科学   120篇
皮肤病学   5篇
神经病学   37篇
特种医学   37篇
外科学   160篇
综合类   1篇
预防医学   76篇
眼科学   11篇
药学   35篇
肿瘤学   34篇
  2023年   7篇
  2022年   12篇
  2021年   36篇
  2020年   20篇
  2019年   24篇
  2018年   23篇
  2017年   19篇
  2016年   16篇
  2015年   15篇
  2014年   30篇
  2013年   34篇
  2012年   58篇
  2011年   64篇
  2010年   37篇
  2009年   22篇
  2008年   38篇
  2007年   43篇
  2006年   29篇
  2005年   33篇
  2004年   38篇
  2003年   33篇
  2002年   27篇
  2001年   3篇
  2000年   9篇
  1999年   6篇
  1998年   5篇
  1997年   4篇
  1996年   3篇
  1995年   3篇
  1994年   2篇
  1992年   8篇
  1991年   5篇
  1990年   6篇
  1987年   2篇
  1985年   3篇
  1984年   4篇
  1983年   3篇
  1982年   1篇
  1981年   3篇
  1980年   1篇
  1979年   2篇
  1978年   4篇
  1977年   8篇
  1976年   2篇
  1975年   4篇
  1974年   1篇
  1972年   1篇
  1971年   3篇
  1970年   1篇
  1966年   2篇
排序方式: 共有761条查询结果,搜索用时 15 毫秒
41.
Summary: Urinary oestriol measurements were performed in 239 rhesus immunized patients with rhesus positive infants. Oestriol excretion was low in 31 of the 55 pregnancies (56%) resulting in perinatal deaths, including 17 of the 26 in which the fetus was hydropic at birth. When oestriol excretion was low the perinatal mortality rate was 65% (31 of 48). When the fetus had severe erythroblastosis, oestriol assays sometimes provided useful extra information when amniotic fluid bilirubin was unexpectedly low.
The important conclusion from this study was that low oestriol excretion was an accurate index for selection of the fetus in jeopardy in rhesus immunized patients, although normal oestriol values did not guarantee that the fetus was in good condition.  相似文献   
42.
Objectives: To ascertain whether plain radiographs interpreted by doctors working in a paediatric ED need reporting by radiologists. Methods: Prospective observational study based in a paediatric teaching hospital. Results: The overall disagreement rate was 26.1%. The clinically significant disagreement rate was 4.8%. There was no relationship between seniority or confidence of ED doctor, and likelihood of disagreement. Disagreement was more likely where radiographs were interpreted during normal working hours (P < 0.05). Chest films, then abdominal films, then skeletal films were more likely to result in disagreement (P < 0.0001). However, this relationship was reversed when considering rates of clinically significant disagreement (P < 0.05). The highest risk of disagreement was in chest films initially thought to be normal, and the lowest in skeletal films initially thought to be abnormal. Conclusion: All radiographs requested on patients discharged from the paediatric ED should be reported. Reporting need not be immediate.  相似文献   
43.
BACKGROUND: Sirolimus has been associated with an increased risk of wound-healing complications in several retrospective analyses. The authors compared the rates of wound-healing complications in renal allograft recipients in a prospective, randomized trial of sirolimus-mycophenolate mofetil-prednisone versus tacrolimus-mycophenolate mofetil-prednisone. METHODS: All patients received antithymocyte globulin induction. In the first phase of the study, patients (n = 77) were included regardless of body mass index (BMI). In the second phase (n = 46 patients), the authors excluded patients with a BMI greater than 32 kg/m2, and the target trough sirolimus level was lowered to 10 to 15 ng/mL (previously 15-20 ng/mL). Multivariate logistic regression analyses were performed to identify predictors of wound complications. RESULTS: Fifty-nine patients received tacrolimus and 64 received sirolimus and were included in subsequent analyses. The incidence of complications was 8% (5 of 59) in the tacrolimus group and 47% (30 of 64) in the sirolimus group (P < 0.0001). Rates of perigraft fluid collections, superficial wound infections, and incisional herniae were significantly higher in the sirolimus group. Multivariate logistic regression showed only sirolimus (P = 0.0001) and BMI (P = 0.0021) to independently correlate with complications. In the first phase of the study, the wound complication rate in the sirolimus group was 55% (21 of 38 patients). After excluding obese recipients and decreasing the target sirolimus level, the wound complication rate in the sirolimus group was 35% (9 of 26 patients; P = 0.1040). CONCLUSIONS: The use of sirolimus-based immunosuppressive regimens leads to a higher incidence of wound-healing complications and will require new approaches to patient selection and management to decrease their incidence.  相似文献   
44.
Widespread applications of totally laparoscopic aortic reconstructions have been limited by the long cross-clamp time required to suture the aortic anastomosis despite improvement in instrumentation. The authors' hypothesis was that a "one-step anastomosis concept" using an intraluminal stapler would allow shorter cross-clamp time but similar patency and imperviousness as videoscopic suturing techniques. An intraluminal stapler (Endopath-ILS, Ethicon) with a modified anvil was used to perform videoscopic-assisted thoracic aorta-to-iliac artery bypass with a 21 mm by 8 mm polytetrafluoroethylene (PTFE) graft in 22 sheep through a minimally invasive approach using a 5 cm thoracotomy. The graft-to-iliac artery anastomoses were hand sutured through a flank incision. Twelve sheep were used to establish the technique and 10 subsequent animals constituted the study group. Aortic cross-clamp time, imperviousness, and need for additional sutures were recorded and compared to previously reported data using videoscopic suturing in pigs. Patency was assessed by comparing lower limb arterial pressures. Macroscopic and microscopic examinations of the anastomoses were performed at different time-points within the first 3 months. Videoscopic-assisted stapled anastomoses were also performed on atherosclerotic aortas of 3 human cadavers. Stapled anastomoses between the thoracic aorta and PTFE graft were completed in 8 of 10 animals. Two animals were euthanized after stapler failure and anastomotic bleeding. Sutures to strengthen the anastomosis had to be used in 4 cases. Mean aortic cross-clamp time in 8 successful cases was 4.3 +/-2.9 minutes (range 2-11 minutes) and was significantly shorter than clamp time of videoscopic suturing technique (48.7 +/-9.4 minutes, p < 0.0001). Imperviousness was good or excellent in 4 animals and fair in 4 animals. All anastomoses were patent at the end of the procedure. Examination of the anastomosis of the 2 failed interventions showed medial aortic tear surrounding the anastomosis in 1 case and misfired staples in the other. No graft occlusion was noted during follow-up ranging from 0 to 12 weeks. At the time of harvest, no bleeding was noted after epinephrine and volume infusion to increase mean arterial pressure to 200 mm Hg for 15 minutes. Macroscopic examination of the anastomoses revealed adequate healing with circumferential stapling of the prosthesis to the aortic wall and no stenosis or thrombus except in 1 false aneurysm (1/7, 14%). Surface electron microscopy showed cells coverage of the anastomosis surface. When applied on human cadaver thoracic and abdominal aorta with atherosclerotic changes, clamping times of less than 5 minutes were achieved. However, imperviousness tested with saline was poor. An automatic stapling device allows performance of a graft-to-aorta anastomosis through a minimally invasive approach with shorter clamping time than a videoscopic suturing technique. However, the current technique of aortic stapling is unreliable and further improvements are needed.  相似文献   
45.
Videoscopic surgical techniques have been developed to reduce morbidity of open aortic reconstructions. The advantage of hand-assisted laparoscopic surgery (HALS) technique is the introduction of the surgeon's hand into the peritoneal cavity. The aims of this study were to assess the feasibility and to examine the learning curve, limitations, and pitfalls of the HALS technique to perform aortic reconstruction in a porcine model for training purposes. HALS aorto-aortic 8 mm polytetrafluoroethylene (PTFE) interposition grafts were placed in 12 pigs. Proficiency was judged by measuring operative time points, satisfactory completion of the operation, and the need to convert to open procedure. The strength of the relationship between order number in which a procedure was performed and the various surgical time point measures was described with the Spearman rank correlation. HALS aortic grafting was successful in the last 8 pigs. The first 2 pigs required conversion to open repair, and the graft of the third and fourth animals occluded early. Median operative time was 115 minutes (range: 75 to 205), median intestinal retraction time was 28 minutes (range: 10 to 40), median aortoiliac dissection time was 30 minutes (range: 20 to 60), and median aortic cross-clamp time was 48 minutes (range: 35 to 82). The Spearman rank correlations and p values between the order of the procedure and the intestinal retraction time, aortoiliac dissection time, clamping time, and total operative time were -0.62 (0.06), -0.47 (0.17), -0.69 (0.03), and -0.83 (0.03), respectively. HALS facilitates intestinal retraction and completion of laparoscopic aortoiliac dissection. It offers adequate exposure in pigs for aortic grafting and allows open sutured aortic anastomosis. The learning curve for HALS aortic surgery in a porcine model is short and within reach of surgeons with standard laparoscopic surgery skills, since no laparoscopic suturing is required. Training on this porcine model may be an efficient and safe way to introduce surgeons to HALS for aortoiliac reconstruction.  相似文献   
46.
BACKGROUND: This paper describes decisions about the experimental design for the Youth, Osteoporosis, and Understanding Total Health Project (YOUTH), a trial designed to test the efficacy of a health plan-based lifestyle intervention for increasing bone mineral density among adolescent women 14 to 16 years of age. METHODS: This randomized controlled trial recruited adolescent women who were at higher risk for developing osteoporosis (body mass index 16-23) from a large HMO in the Pacific Northwest. The intervention focused on improving diet (high calcium foods, fruits, and vegetables) and increasing physical activity (high impact and spinal motion). The intervention included both group and individual activities. The primary endpoint in the study was total bone mineral density as measured by dual-energy X-ray absorptiometry (DEXA). RESULTS: Baseline data were collected on the trial cohort of 228 adolescent women and their families. This paper discusses how researchers met the following challenges in designing and implementing the trial: determining appropriate dietary and exercise targets to affect bone mineral density in adolescents; choosing suitable assessments; and developing an intervention well suited for implementation in a non-school (health plan) setting. We also discuss the rationale for the specific study population chosen (females, younger adolescents). CONCLUSIONS: The YOUTH project is one of very few preventive research interventions with adolescents conducted in a health plan setting. Many of the recruitment and intervention strategies used in this trial may be appropriate for adoption in other health plan-based prevention studies.  相似文献   
47.
Urinary incontinence is a significant health care problem affecting women and men of all races and cultures. Existing literature provides a limited evidence base with which to influence UI practice. More research is needed to fully understand the influences of gender, race, culture, or ethnicity on the patient's experience of UI and its management. The matter is particularly relevant for nurses who want to understand and help people cope with the adverse physical and psychosocial consequences of this chronic, socially isolating, and potentially devastating disorder.  相似文献   
48.
OBJECTIVE: To test the substitution hypothesis, that community-based care reduces the probability of institutional placement for at-risk elderly. RESEARCH DESIGN: The closure of the Social Health Maintenance Organization (Social HMO) at HealthPartners (HP) in Minnesota in 1994 and the continuation of the Social HMO at Kaiser Permanente Northwest (KPNW) in Oregon/Washington comprised a "natural experiment." Using multinomial logistic regression analyses, we followed cohorts of Social HMO enrollees for up to 5 years, 1995 to 1999. To adjust for site effects and secular trends, we also followed age- and gender-matched Medicare-Tax Equity and Fiscal Responsibility Act (TEFRA) cohorts, enrolled in the same HMOs but not in the Social HMOs. SUBJECTS: All enrollees in the Social HMO for at least 4 months in 1993 and an age-gender matched sample of Medicare-TEFRA enrollees. To be included, individuals had to be alive and have a period out of an institution after January 1, 1995 (total n = 18,143). MEASURES: The primary data sources were the electronic databases at HP and KPNW. The main outcomes were long-term nursing home placement (90+ days) or mortality. Covariates were age, gender, a comorbidity index, and geographic site effect. RESULTS: Adjusting for variations in the 2 sites, we found no difference in probability of mortality between the 2 cohorts, but approximately a 40% increase in long-term institutional placement associated with the termination of the Social HMO at HealthPartners (odds ratio, 1.43; 95% confidence interval, 1.15-1.79). CONCLUSIONS: The Social HMO appears to help at-risk elderly postpone long-term nursing home placement.  相似文献   
49.
50.
BACKGROUND: Worldwide, type 2 diabetes prevalence is increasing, with Native American populations particularly at risk. The Zuni Pueblo, with a history of wellness activities, volunteered to test the feasibility and efficacy of a high school-based diabetes prevention intervention. METHODS: This school-based intervention used a multiple cross-sectional design to evaluate outcome measures at 0, 1.5, and 3 years against an Anglo comparison group. The Zuni high school diabetes prevention program included an educational component targeting decreased consumption of sugared beverages, knowledge of diabetes risk factors, and a youth-oriented fitness center. Main outcome measures were plasma glucose and insulin measured fasting and 30 min after a 75-g glucose challenge. RESULTS: Plasma glucose levels were normal at baseline for Zuni (n = 72) and Anglo (n = 37) youth and did not significantly change throughout the study. At baseline, fasting and 30-min plasma insulin levels were significantly elevated for Zuni youth; they showed significant steady declines for both males and females throughout the study (P = 0.06 to P = 0.000 for trends using quantile regression). By Year 3, values for Zuni males (n = 29) equaled Anglo comparison values, while Zuni female (n = 26) values had declined but were still higher than Anglo comparison values. CONCLUSIONS: Among at-risk youth, an environmentally based lifestyle intervention may significantly suppress markers of type 2 diabetes risk.  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