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   55369篇
  免费   5804篇
  国内免费   1568篇
耳鼻咽喉   640篇
儿科学   932篇
妇产科学   945篇
基础医学   2339篇
口腔科学   1340篇
临床医学   10762篇
内科学   5488篇
皮肤病学   718篇
神经病学   2366篇
特种医学   1310篇
外国民族医学   5篇
外科学   4516篇
综合类   7244篇
现状与发展   1篇
一般理论   3篇
预防医学   10423篇
眼科学   791篇
药学   5201篇
  242篇
中国医学   4576篇
肿瘤学   2899篇
  2024年   347篇
  2023年   1456篇
  2022年   2237篇
  2021年   3078篇
  2020年   3267篇
  2019年   2765篇
  2018年   2499篇
  2017年   2744篇
  2016年   2610篇
  2015年   2507篇
  2014年   4425篇
  2013年   4593篇
  2012年   3793篇
  2011年   3704篇
  2010年   2835篇
  2009年   2749篇
  2008年   2739篇
  2007年   2574篇
  2006年   2310篇
  2005年   1823篇
  2004年   1522篇
  2003年   1268篇
  2002年   972篇
  2001年   778篇
  2000年   586篇
  1999年   467篇
  1998年   350篇
  1997年   324篇
  1996年   267篇
  1995年   247篇
  1994年   180篇
  1993年   159篇
  1992年   143篇
  1991年   81篇
  1990年   63篇
  1989年   56篇
  1988年   37篇
  1987年   36篇
  1986年   15篇
  1985年   27篇
  1984年   32篇
  1983年   13篇
  1982年   15篇
  1981年   18篇
  1980年   7篇
  1979年   8篇
  1978年   5篇
  1977年   2篇
  1974年   2篇
  1973年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
医疗机构实施ISO9001,其目的是为了提高医疗服务质量,满足病人一切明确和隐含的需求。那么,内审是否发挥作用,直接关系管理体系的有效性。文章对此进行了初步的探讨,即:①明确内审的目的是检查体系满足标准要求的程度;②建立正规的内审机构,要选拔责任心强、综合素质高的人担任内审员;③编制合理且有特色的内审计划,是内审有效性的关键;④适当增加专题审核;⑤医院最高管理者应重视内审结果。  相似文献   
72.
73.
BACKGROUND: Studies have suggested that the quality of human semen has been declining over recent decades, presumably because of lifestyle or environmental factors. METHODS: Polychlorinated biphenyls and organochlorine pesticides were analysed in the plasma of 25 men with poor semen quality, 20 men with normal semen quality and idiopathic subfertility and 27 men with normal semen quality and female factor subfertility. Samples of seminal fluid were also analysed to assess the relationship between the levels in blood and semen. RESULTS: The results indicate no difference in the levels of organochlorines between the groups. The levels of organochlorines in seminal fluid were proportional to the levels in plasma, but approximately 40 times lower. Men with poor semen quality were three times more likely to be obese than men with normal semen quality. There was also a significant negative correlation between semen quality parameters and body mass index among men with normal semen quality. The prevalence of sedentary work was lowest among men with the best semen quality. CONCLUSIONS: Poor semen quality was found to be associated with sedentary work and obesity but not with plasma levels of persistent organochlorines. More research is needed to assess whether sedentary lifestyle and obesity are causal factors in the decline of semen quality.  相似文献   
74.
BACKGROUND: There is a large variability in clinical response to corticosteroid treatment in patients with asthma. Several markers of inflammation like eosinophils and eosinophil cationic protein (ECP), as well as exhaled nitric oxide (NO), are good candidates to predict clinical response. AIM: We wanted to determine whether we could actually predict a favourable response to inhaled corticosteroids in individual patients. METHODS: One hundred and twenty patients with unstable asthma were treated with either prednisolone 30 mg/day, fluticasone propionate 1000 microg/day b.i.d. or fluticasone propionate 250 microg/day b.i.d., both via Diskhaler. They were treated during 2 weeks, in a double-blind, parallel group, double dummy design. We measured eosinophils and ECP in blood and sputum, and exhaled nitric oxide as inflammatory parameters before and after 2 weeks in order to predict the changes in forced expiratory volume in 1 s (FEV1), provocative concentration of methacholine causing a 20% fall in FEV1 (PC20 Mch), and asthma quality of life (QOL). Secondly, to test whether these results were applicable in clinical practice we determined the individual prediction of corticosteroid response. RESULTS: We found that changes in FEV1, PC20 Mch and QOL with corticosteroids were predominantly predicted by their respective baseline value and to a smaller extent by eosinophils in blood or sputum. ECP, measured in blood or sputum, was certainly not better than eosinophils in predicting clinical response to corticosteroids. Smoking status was an additional predictor for change in FEV1, but not for change in PC20 Mch or QOL. Prediction of a good clinical response was poor. For instance, high sputum eosinophils (> or = 3%) correctly predicted an improvement in PC20 Mch in only 65% of the patients. CONCLUSION: Our findings show that baseline values of the clinical parameters used as outcome parameters are the major predictors of clinical response to corticosteroids. Eosinophil percentage in blood or sputum adds to this, whereas ECP provides no additional information. Correct prediction of clinical response in an individual patient, however, remains poor with our currently used clinical and inflammatory parameters.  相似文献   
75.
Genetic carrier testing of children is usually not recommended. However, there are no data concerning long-term psychological consequences, experience, and satisfaction of those tested as well as their recall of the test results. We evaluated these items retrospectively 10–24 years after carrier testing performed in childhood. Study material comprised 25 families with aspatylglucosaminuria (AGU), an autosomal recessive disorder, with 35 healthy sibs from all parts of Finland tested for carriership during childhood between 1973 and 1987. Of these sibs, 25 participated in our study. The questionnaire comprised multiple-choice and open-ended questions. The psychosocial well-being of the study subjects measured by the RAND 36 item Health Survey 1.0 (RAND) was, in general, at least as good as that of controls, and showed no significant differences between carriers and non-carriers (p>0.154). All tested individuals were satisfied with the fact that they had been tested and stated that the decision to perform carrier testing on a child can be made by the parents. Of the 25 tested, 23 knew and understood their test result correctly at the time of our study. Most of the tested individuals (60%) stated that the best time for carrier testing would be in the childhood or in the teen years.
This study indicates that carrier testing in childhood for an autosomal recessive disorder (AGU) had caused no measurable disturbance of quality of life in adulthood, and those tested reported being satisfied. However, we do not recommend testing in childhood, as the result is not needed prior to the time for reproductive decisions.  相似文献   
76.
BACKGROUND: Few studies have measured pigeon allergens in non pigeon coop environments. This study was conducted to determine approximate pigeon dropping allergen concentrations in indoor environments. METHODS: Polyclonal antibody serum was prepared by injecting a rabbit three times with crude wild pigeon dropping extract in 50 mM Tris buffer with Freund's adjuvant. One hundred and fifteen dust samples were collected in a pigeon-infested school, pigeon coops, homes and hospitals and analyzed by a direct competitive pigeon enzyme-linked immunosorbent assay (ELISA). RESULTS: The highest level of pigeon allergen inhibitory activity were recorded in four samples from pigeon coop bedding samples with a median activity of 11.2% relative to pigeon droppings. The second highest level of pigeon allergens was in a pigeon-infested high school with a median or 7.4% activity relative to pigeon droppings. At an entrance underneath pigeon roosts, one sample had a relative inhibitory activity of 62.3%. Pigeon allergen inhibitory levels were generally low in the home and hospital samples, but nevertheless 46 out of 89 of these samples were still above detection limit. CONCLUSIONS: This study suggests that large concentrations of pigeon allergens can be found in buildings without domestic pigeons such as the pigeon-infested high school.  相似文献   
77.
In 18-week-old nulliparous rabbit dose, ovulation was inducedwith 50 IU of pure urinary luteinizing hormone (LH; LHgroup),or 50 IU of ohuman chorionic gonadotrophin (HCG; HCG group),in order to detemine the effect of these treatments on 17-oestradioland progesterone concentrations, and on oocyte and embryo quality.Luteinizing follicles, recovered oocytes, progesteronoe concentrationand grade 5 embryos were significantly reduced when pure urinaryLH was used. Statistically significant correlations were found:(i) between oestradiol concentration and number of degeneratedoocytes in both groups (positive); (ii) between oestradiol concentrationand grade 1 and 2 embrayos (negative), and grade 5 embryos (positive)in the HCG group; (iii) between progesteronoe concentrationand metaphase II oocytes(negatice), and between progesteroneand grade 5 sembryos (positive), in the HCG group; and (iv)between progesterone and oestradiol concentrations (negative)in the LH group. It seems that the oestrsdiol to progegsteroneratio improves during the early luteal phase when ovulationis induced with LH, and that oestradiol and progesterone concentrationscould play a role in dtermining oocyte and embryo quality  相似文献   
78.
79.
Critically ill patients in the intensive care unit (ICU) have a high risk of developing malnutrition, and this is associated with poorer clinical outcomes. In clinical practice, nutrition, including enteral nutrition (EN), is often not prioritized. Resulting from this, risks and safety issues for patients and healthcare professionals can emerge. The aim of this literature review, inspired by the Rapid Review Guidebook by Dobbins, 2017, was to identify risks and safety issues for patient safety in the management of EN in critically ill patients in the ICU. Three databases were used to identify studies between 2009 and 2020. We assessed 3495 studies for eligibility and included 62 in our narrative synthesis. Several risks and problems were identified: No use of clinical assessment or screening nutrition assessment, inadequate tube management, missing energy target, missing a nutritionist, bad hygiene and handling, wrong time management and speed, nutritional interruptions, wrong body position, gastrointestinal complication and infections, missing or not using guidelines, understaffing, and lack of education. Raising awareness of these risks is a central aspect in patient safety in ICU. Clinical experts can use a checklist with 12 identified top risks and the recommendations drawn up to carry out their own risk analysis in clinical practice.  相似文献   
80.
Macro and micronutrient deficiencies pose serious health challenges globally, with the largest impact in developing regions such as subSaharan Africa (SSA), Latin America and South Asia. Maize is a good source of calories but contains low concentrations of essential nutrients. Major limiting nutrients in maize-based diets are essential amino acids such as lysine and tryptophan, and micronutrients such as vitamin A, zinc (Zn) and iron (Fe). Responding to these challenges, separate maize biofortification programs have been designed worldwide, resulting in several cultivars with high levels of provitamin A, lysine, tryptophan, Zn and Fe being commercialized. This strategy of developing single-nutrient biofortified cultivars does not address the nutrient deficiency challenges in SSA in an integrated manner. Hence, development of maize with multinutritional attributes can be a sustainable and cost-effective strategy for addressing the problem of nutrient deficiencies in SSA. This review provides a synopsis of the health challenges associated with Zn, provitamin A and tryptophan deficiencies and link these to vulnerable societies; a synthesis of past and present intervention measures for addressing nutrient deficiencies in SSA; and a discussion on the possibility of developing maize with multinutritional quality attributes, but also with adaptation to stress conditions in SSA.  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