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   741篇
  免费   31篇
  国内免费   24篇
儿科学   32篇
妇产科学   4篇
基础医学   58篇
口腔科学   9篇
临床医学   93篇
内科学   141篇
皮肤病学   14篇
神经病学   5篇
特种医学   185篇
外科学   70篇
综合类   3篇
预防医学   76篇
眼科学   9篇
药学   51篇
肿瘤学   46篇
  2024年   2篇
  2023年   2篇
  2022年   2篇
  2021年   8篇
  2020年   5篇
  2019年   3篇
  2018年   11篇
  2017年   5篇
  2016年   8篇
  2015年   9篇
  2014年   19篇
  2013年   27篇
  2012年   12篇
  2011年   18篇
  2010年   22篇
  2009年   10篇
  2008年   20篇
  2007年   37篇
  2006年   23篇
  2005年   28篇
  2004年   22篇
  2003年   13篇
  2002年   12篇
  2001年   13篇
  2000年   19篇
  1999年   10篇
  1998年   34篇
  1997年   48篇
  1996年   28篇
  1995年   27篇
  1994年   20篇
  1993年   12篇
  1992年   8篇
  1991年   13篇
  1990年   16篇
  1989年   26篇
  1988年   28篇
  1987年   18篇
  1986年   21篇
  1985年   26篇
  1984年   13篇
  1983年   8篇
  1982年   16篇
  1981年   7篇
  1980年   16篇
  1979年   7篇
  1978年   9篇
  1977年   8篇
  1976年   15篇
  1975年   4篇
排序方式: 共有796条查询结果,搜索用时 31 毫秒
71.
72.
73.
BACKGROUND AND OBJECTIVES: Atherosclerosis is a multifactorial disease, in part characterized by chronic inflammatory changes in the vessel wall and loss of normal physical and biochemical interactions between endothelial cells and smooth muscle cells. Previous studies [Hu J., Cotgreave IA. J Clin Invest; 99: 1-5] have provided molecular links between inflammation and myoendothelial communication via gap junctions, suggesting that these structures may be important in the development of the atherosclerotic vessel phenotype. In order to strengthen this premise, the aim of the present work was to probe for structural polymorphisms in connexin 37, a gap junctional protein uniquely expressed in endothelial cells, and to assess for potential genotypic segregation in individuals displaying atherosclerotic plaque. METHODS AND RESULTS: Computer-based comparisons of Expressed Sequence Tags (ESTs) predicted a polymorphism in the human gap junctional protein connexin 37 (cx37). The C1019-T mutation results in a proline to serine shift at codon 319 (cx37*1-cx37*2). A Restriction Fragment Length Polymorphism (RFLP) assay, involving the insertion of a novel Drd I cleavage site in the proline variant revealed a statistically significant over-representation of the cx37*1 allele in association with atherosclerotic plaque-bearing individuals (Odds-ratio for the homozygote = 2.38, Chi2 = 7.693, P = 0.006), in comparison to individuals lacking plaque, irrespective of a history of hypertension. CONCLUSIONS: These data suggest that the C1019-T polymorphism in cx37 may provide 'single gene marker', which could be useful in assessing atherosclerotic plaque development, particularly in cardiovascular risk groups such as those with borderline hypertension.  相似文献   
74.
Specificity of autoantibodies in autoimmune thrombocytopenia   总被引:12,自引:5,他引:12  
In 42 patients with autoimmune thrombocytopenia (AITP) and a positive direct platelet suspension immunofluorescence test (PSIFT), the antigenic specificity of the autoantibodies was studied. Because the autoantibodies were often not detectable in the serum and additional HLA antibodies may disturb the reaction pattern with the platelet panel, we used eluates prepared from the patients' platelets for this study. Thirty-five patients had antibodies equally reactive with normal platelets, irrespective of their antigenic make-up, but not with the platelets from two Glanzmann's disease patients. Absorption and elution experiments in two patients showed that his was probably not due to the presence of a combination of anti-Zwa and anti-Zwb antibodies. Thus, the majority of autoantibodies against platelets seems to be directed against antigenic determinants not present on Glanzmann's disease platelets, but perhaps located on the platelet-membrane glycoproteins IIb and/or IIIa. In ten patients, antibodies of no, or still unknown, specificity were detected. Three of these had additional antibodies not reactive with the platelets of the two Glanzmann patients.  相似文献   
75.
76.

Background

Choledochocystolithiasis can be managed by endoscopic retrograde cholangiopancreaticography (ERCP) or laparoscopically by transcystic (TC) or transductal (TD) stone extraction.

Objective

The aim of this study was to systematically review safety and effectiveness of combined endoscopic/laparoscopic management versus total laparoscopic management for choledochocystolithiasis with specific emphasis on TC versus TD stone extraction.

Methods

MEDLINE/PubMed, EMBASE, the Cochrane Library, and clinicaltrials.gov were searched systematically to identify trials on combined endoscopic/laparoscopic and total laparoscopic management for choledochocystolithiasis. Laparoscopic common bile duct (CBD) exploration was divided into TD and TC approach. Primary outcomes were successful stone clearance from CBD, postoperative/procedural morbidity, and mortality.

Results

Eight randomized trials with 965 patients were included. Successful bile duct clearance varied between 52.6 and 97 % in the ERCP groups, 80.4 and 100 % in the TC groups, and 58.3 and 100 % in the TD groups. There were more bile leaks after TD stone extraction (11 %) than after ERCP (1 %) and TC stone extraction (1.7 %). Total morbidity varied between 9.1 and 38.3 % in the ERCP groups, 7 and 10.5 % in the TC groups, and 18.4 and 26.7 % in the TD groups. Methodological and statistical heterogeneity among the trials precluded a meaningful meta-analysis.

Conclusion

Stone clearance rates are comparable between the three modalities, but TD stone extraction is associated with a higher risk of bile leaks and should only be performed by highly experienced surgeons. TC stone extraction seems a more accessible technique with lower complication rates. If unsuccessful, per- or postoperative endoscopic stone extraction is a viable option.  相似文献   
77.
The prevalence of osteopenia in children with inflammatory bowel disease (IBD) is unknown. The effect of nutritional state, disease activity, and steroid therapy on bone mineral content (BMC) of whole body, lumbar spine, and left femoral neck measured by dual energy x ray absorptiometry in 32 children with IBD was assessed by comparison with 58 healthy local school children. Using the control data, a predicted BMC was calculated taking into account bone area, age, height, weight, and pubertal stage. The measured BMC in children with IBD was expressed as a percentage of this predicted value (% BMC). Mean (SD) % BMC was significantly reduced for the whole body and left femoral neck in the children with IBD (97.0 (4.5)% and 93.1 (12.0)% respectively, p < 0.05). Of the children with IBD, 41% had a % BMC less than 1 SD below the mean for the whole body and 47% at the femoral neck. Reduction in % BMC was associated with steroid usage but not with the magnitude of steroid dose, disease activity, or biochemical markers of bone metabolism. In conclusion, osteopenia is relatively common in childhood IBD and may be partly related to the previous use of steroids.  相似文献   
78.

Background

The purpose of this study was to determine the test-retest reliability of temporal and spatial gait measurements over a one-week period as measured using an instrumented walkway system (GAITRite®).

Methods

Subjects were tested on two occasions one week apart. Measurements were made at preferred and fast walking speeds using the GAITRite® system. Measurements tested included walking speed, step length, stride length, base of support, step time, stride time, swing time, stance time, single and double support times, and toe in-toe out angle.

Results

Twenty-one healthy subjects participated in this study. The group consisted of 12 men and 9 women, with an average age of 34 years (range: 19 – 59 years). At preferred walking speed, all gait measurements had ICC's of 0.92 and higher, except base of support which had an ICC of 0.80. At fast walking speed all gait measurements had ICC's above 0.89 except base of support (ICC = 0.79),

Conclusions

Spatial-temporal gait measurements demonstrate good to excellent test-retest reliability over a one-week time span.
  相似文献   
79.
80.

OBJECTIVES:

To determine patterns of follow-up and prenatal education by family physicians and to assess whether practice patterns comply with the 1996 Canadian Paediatric Society/Society of Obstetricians and Gynecologists of Canada (CPS/SOGC) guidelines for early neonatal discharge.

DESIGN:

Mail survey.

SETTING:

A community of 300,000 people who were served exclusively for obstetrical care by a tertiary care hospital that performs 5000 deliveries per year and provides an early discharge program (EDP).

PARTICIPANTS:

Family physicians who provide prenatal and/or newborn care.

MAIN OUTCOME MEASURES:

The timing of neonatal follow-up and parental teaching by family physicians.

RESULTS:

Thirty-two per cent of the respondents scheduled their first postnatal visits two or more weeks after early discharge. There was no significant difference (P=0.7) in scheduling of follow-up for babies who were part of an EDP compared with those who were not. Fewer than 20% of physician respondents provided antenatal education in preparation for early discharge.

CONCLUSIONS:

The 1996 CPS/SOGC guidelines for physician follow-up after early neonatal discharge and for anticipatory parental education are not being followed consistently; however, these guidelines were disseminated without reinforcement. Until further study supports a change in practice guidelines, appropriate implementation strategies must be employed to ensure compliance.  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