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   3635篇
  免费   175篇
  国内免费   27篇
耳鼻咽喉   53篇
儿科学   52篇
妇产科学   78篇
基础医学   359篇
口腔科学   118篇
临床医学   292篇
内科学   923篇
皮肤病学   47篇
神经病学   357篇
特种医学   140篇
外科学   490篇
综合类   8篇
一般理论   2篇
预防医学   151篇
眼科学   54篇
药学   265篇
中国医学   3篇
肿瘤学   445篇
  2023年   29篇
  2022年   56篇
  2021年   99篇
  2020年   75篇
  2019年   72篇
  2018年   69篇
  2017年   72篇
  2016年   89篇
  2015年   98篇
  2014年   103篇
  2013年   172篇
  2012年   248篇
  2011年   255篇
  2010年   137篇
  2009年   133篇
  2008年   227篇
  2007年   240篇
  2006年   236篇
  2005年   256篇
  2004年   251篇
  2003年   234篇
  2002年   189篇
  2001年   39篇
  2000年   29篇
  1999年   29篇
  1998年   24篇
  1997年   19篇
  1996年   22篇
  1995年   24篇
  1994年   36篇
  1993年   14篇
  1992年   22篇
  1991年   15篇
  1990年   15篇
  1989年   22篇
  1988年   14篇
  1987年   19篇
  1986年   13篇
  1985年   16篇
  1984年   19篇
  1983年   10篇
  1982年   13篇
  1981年   11篇
  1980年   12篇
  1979年   5篇
  1978年   8篇
  1975年   3篇
  1974年   4篇
  1973年   4篇
  1971年   3篇
排序方式: 共有3837条查询结果,搜索用时 0 毫秒
991.
BACKGROUND: Despite the high prevalence of sleep disorders in patients with kidney disease, no relationship has been demonstrated between sleep quality and the degree of renal function in cross-sectional studies. A prospective trial was, therefore, started in patients with chronic renal failure (CRF) to evaluate whether a link exists between the modifications of these parameters observed during a three-year follow-up period. METHODS: Sleep quality was determined by the Pittsburgh Sleep Quality Index (PSQI) at baseline and after two and three years (Time 0, 2 and 3, respectively) in 78 patients with various degrees of CRF in association with the main clinical and biochemical variables. RESULTS: The baseline PSQI averaged 6.2+/-3.8 (range: 0-21, with higher values indicating worse sleep quality) and was significantly increased at both Time 2 and 3 (8.8+/-3.7 and 10.2+/-3.5, respectively, P<0.0001 vs baseline), whereas creatinine clearance progressively decreased (45+/-24 vs 41+/-26 and 32+/-20ml/min, at time 0, 2 and 3, respectively, P<0.0001), although an independent association with PSQI could not be demonstrated after adjustment for confounding factors (P=0.90, mixed linear model). CONCLUSIONS: Our data suggest that the progression of renal disease is accompanied by a progressive worsening of sleep quality; age is strongly related to both phenomena. PSQI represents an easy tool to use to detect sleep disorders and to more effectively evaluate renal patients; the prevention of sleep disorders by early and appropriate treatments could beneficially influence the course of the disease.  相似文献   
992.
993.
994.
The V gamma 2 V delta 2 T cell subset responds to Bacille Calmette-Guerin (BCG) immunization in macaques and may be a component of protective immunity against tuberculosis. We characterized the effects of BCG on the V gamma 2 V delta 2 T cell receptor repertoire by comparing the starting population of V gamma 2 chains in cynomolgus macaques with the repertoire found after priming or booster immunization with BCG. The starting repertoire was dominated by public V gamma 2 chain sequences that were found repeatedly among unrelated animals. Primary exposure to BCG triggered expansion of cells expressing public V gamma 2 chains and booster immunization was often associated with contraction of these same subsets. Thus, BCG-reactive V gamma 2 chains were present at high frequency in the repertoire of mycobacteria-na?ve macaques and they comprised the major response to primary or booster immunization. Normal selection processes that created the na?ve V gamma 2 repertoire in macaques, also encoded the capacity for rapid responses to mycobacteria. The unusual composition of a normal V gamma 2 repertoire helps to explain the powerful gammadelta T cell responses to BCG immunization.  相似文献   
995.
996.
BACKGROUND/OBJECTIVES: Expert oral anticoagulation management is the key to good outcomes and is performed variably in different health care systems throughout the world. We set out to assess the quality of anticoagulation management in five countries in patients receiving vitamin K antagonists (VKAs) for stroke prophylaxis in chronic non-valvular atrial fibrillation (NVAF), and to compare the anticoagulation management practices in these countries. METHODS AND RESULTS: This was a retrospective, multi-centre cohort study in the United States, Canada, France, Italy, and Spain. About 1,511 patients were randomly recruited from representative practices (routine medical care (RMC) in the US, Canada, and France; anticoagulation clinics in Italy and Spain) and data pertaining to their oral anticoagulation care were abstracted from their medical records. The predominant anticoagulant in use was warfarin in the US, Canada, and Italy; acenocoumarol in Spain; and fluindione in France. Documentation of care was poor in the US, Canada, and France, countries where RMC was studied. Percent INRs or time-in-therapeutic range was greater in the two anticoagulation clinic samples compared with the RMC samples. CONCLUSION: Oral anticoagulation care varies considerably from country to country. Findings suggest that anticoagulation clinic care (ACC) may provide better outcomes as assessed by international normalized ratio (INR) time-in-range. Physicians tend to under treat more than over treat. Finally, documentation of care is often inadequate. Condensed Abstract Oral anticoagulation management (routine medical care or anticoagulation clinic care) was retrospectively assessed in 5 countries using a uniform, structured assessment tool. Major management differences were detected, especially between anticoagulation clinic care and routine care. Documentation was often a problem in the latter setting. Less time in therapeutic INR range was noted in routine medical care. Findings suggest that anticoagulation clinic care may provide better outcomes as assessed by international normalized ratio (INR) time-in-range. Physicians tend to under treat more than over treat. Finally, documentation of care is often inadequate.  相似文献   
997.
BACKGROUND: Endothelial dysfunction in cigarette smokers has been ascribed to increased oxidative damage. The aims of the present study were to compare the endothelial function of normotensive smokers with that of non-smokers and to examine its relation to some parameters representative of oxidative damage and of antioxidant capacity. METHODS: We investigated 32 chronic smokers (15-30 cigarettes daily) affected by coronary heart disease, ranging from acute myocardial infarction to instable angina pectoris, and 28 matched non-smokers without any definite risk factors. All subjects underwent assessment of nitric oxide (NO)-dependent endothelial function, measured as brachial artery vasodilatation in response to reactive ischemia, using a standardized echographic method. Plasma and urinary levels of NO were also measured in all subjects, as were urinary 15-isoprostane F(2t), plasma serum lipids, homocysteine (Hcy), ascorbic acid, retinol, tocopherol, and alpha- and beta-carotene (by high-performance liquid chromatography). RESULTS: Smokers showed a significantly lower NO-mediated vasodilatation response (3.50% vs. 6.18%, p<0.001) and higher levels of urinary NO metabolites and 15-isoprostane F(2t). They also had higher levels of Hcy (p<0.001); these values were significantly and inversely related to NO serum levels (r=-0.512, p<0.001). Moreover, smokers had a significant and corresponding reduction in circulating levels of ascorbic acid, tocopherol, and alpha- and beta-carotene. CONCLUSIONS: The present study shows a clear relation between endothelial dysfunction (NO production impairment) and cigarette smoking, especially in the presence of high levels of LDL-cholesterol. It also defines some markers of both oxidative damage and antioxidant protective capacity in this condition. The monitoring of these factors may be advisable in order to assess the amount of endothelial damage.  相似文献   
998.
Bortezomib is the first anticancer proteasome inhibitor introduced into clinical practice. It has been recently approved for the treatment of multiple myeloma, an incurable plasma cell tumour that accounts for 10-15% of all haematologic malignancies and for approximately 20% of deaths. Gastrointestinal toxicity associated with the use of this drug is common but generally mild to moderate. Paralytic ileus in patients undergoing bortezomib treatment has been reported, although a definite attribution to bortezomib administration has not been established. We report a myeloma patient who developed severe paralytic ileus during bortezomib therapy, which presented in the context of progressive constipation without other known causes and which regressed promptly with medical management after drug cessation, suggesting a direct causal relationship. Awareness of the various potential gastrointestinal toxic effects of bortezomib is of relevance given the growing number of patients undergoing treatment with this important and effective new cancer drug.  相似文献   
999.
1000.
Introduction The object of neoadjuvant chemoradiotherapy regimens is a downstaging or downsizing of advanced rectal tumor to increase the rate of curative resection and reduce loco-regional failure. A reliable method of assessing response to adjuvant therapies is required to help standardize the assessments of new multimodality therapies. The purpose of this study was to evaluate the role played by tumor regression grading on the evaluation of pathological response to chemoradiotherapy, compared with both the predicting value of the clinical response to neoadjuvant therapy and pathologic response evaluation.Methods From 1994 to 2003, 58 patients with a primary diagnosis of rectal cancer were studied at our department and enrolled in a single center, not randomized study based on 5-week sessions of radiotherapy associated with a 30-day 5-fluorouracil (FU) infusion, followed by surgical resection. Instrumental restaging and routine histological examination, including tumor regression grading, were performed to asses the response to neoadjuvant therapy.Results The cCR rate corresponds to pCR rate, while a 3.5% of cPR and a 3.4% of cSD corresponded to a pPD. cPR and cSD show a PPV of 92.8% and 90.9% respectively, while cPD NPV is 20%. No case was found with no regression (grade 0). Tumor regression was defined grade 1 in 24.5% of cases, grade 2 was found in 58.5% of cases, 7.5% were grade 3, and 9.5% showed complete regression (grade 4). Pathologic response resulted to be associated with regression grade (p=0.006). Tumor regression grading is an independent variable for pT (p=0.0002), pN status (p=0.00004), pathologic staging (p=0.000001) and local recurrence (p=0.003).Conclusion Our results lead us to consider only pathologic evaluation to determine the response to neoadjuvant treatment: the application of tumor regression grading on the specimens obtained after combined neoadjuvant chemoradiotherapy and surgery is useful to plan a better therapeutic strategy on the ground of a quantitative evaluation of the response to neoadjuvant treatment; it shows it is an important comparable pathological feature, useful in comparing different protocols’ results and differences between patient’s response as well as prognostic factors.  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