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   2703篇
  免费   236篇
  国内免费   104篇
耳鼻咽喉   9篇
儿科学   100篇
妇产科学   144篇
基础医学   427篇
口腔科学   52篇
临床医学   261篇
内科学   416篇
皮肤病学   20篇
神经病学   166篇
特种医学   53篇
外科学   170篇
综合类   516篇
预防医学   148篇
眼科学   81篇
药学   228篇
  7篇
中国医学   135篇
肿瘤学   110篇
  2024年   8篇
  2023年   38篇
  2022年   78篇
  2021年   124篇
  2020年   97篇
  2019年   92篇
  2018年   84篇
  2017年   108篇
  2016年   94篇
  2015年   111篇
  2014年   148篇
  2013年   182篇
  2012年   154篇
  2011年   162篇
  2010年   124篇
  2009年   117篇
  2008年   108篇
  2007年   124篇
  2006年   116篇
  2005年   100篇
  2004年   94篇
  2003年   80篇
  2002年   59篇
  2001年   53篇
  2000年   60篇
  1999年   41篇
  1998年   43篇
  1997年   39篇
  1996年   36篇
  1995年   38篇
  1994年   32篇
  1993年   28篇
  1992年   27篇
  1991年   22篇
  1990年   29篇
  1989年   16篇
  1988年   25篇
  1987年   8篇
  1986年   22篇
  1985年   19篇
  1984年   26篇
  1983年   13篇
  1982年   16篇
  1981年   5篇
  1980年   11篇
  1979年   8篇
  1978年   7篇
  1977年   5篇
  1973年   3篇
  1968年   2篇
排序方式: 共有3043条查询结果,搜索用时 15 毫秒
11.
BACKGROUND: In chronic ambulatory peritoneal dialysis, bicarbonate-buffered fluids, with their neutral pH and less advanced glycosylation end-products (AGE) and glucose degradation products (GDP), have better biocompatibility than conventional peritoneal dialysis (PD) solutions. That difference may be more beneficial in automated peritoneal dialysis (APD), due to its more frequent exchanges and longer contact times with fresh dialysate. We performed a prospective, randomized study in APD patients to compare the biocompatibility of conventional and bicarbonate/lactate-buffered PD fluids. METHODS: We randomized 14 APD patients to have APD with either conventional or bicarbonate/lactate-based fluids. After 6 months, both groups changed to the other solution. The overall observation period was 12 months. After 1 and 5 months and again after 7 and 11 months, phagocytotic and respiratory burst capacities of effluent peritoneal macrophages were determined. Plasma interleukin (IL)-6 and C-reactive protein (CRP) as well as effluent IL-6, CRP, transforming growth factor (TGF)-beta 1, AGE and CA125 concentrations were measured. Inflow pain was quantified using a patient questionnaire. RESULTS: Respiratory burst capacity remained unchanged and phagocytotic activity increased significantly during APD (P<0.001) with the bicarbonate/lactate fluid. Effluent IL-6 release was significantly lower than with the lactate fluid (P<0.05). While in the effluent TGF-beta 1 was unaffected, AGE concentration was lower after bicarbonate/lactate treatment (P<0.05). Effluent CA125 concentration, an indicator of mesothelial cell integrity, was higher (P<0.05) in neutral effluents. Finally, patients' inflow pain diminished (P = 0.05) when using the neutral fluid. CONCLUSIONS: The use of a neutral PD fluid in APD improved patients' inflow pain as well as biocompatibility parameters reflecting enhanced phagocytotic activity of peritoneal macrophages, reduced constitutive inflammatory stimulation (IL-6), reduced AGE accumulation in the peritoneal cavity and better preservation of the mesothelial cell integrity. From the biocompatibility point of view, a neutral fluid with low GDP content can be recommended as the primary choice for APD.  相似文献   
12.
Background: The Farnsworth D15 test is designed to categorise colour vision deficiency as severe or moderate. The level of difficulty of the test was set so that those who passed it should be able to recognise surface colour codes, such as those used for electrical wiring. The test is widely used to provide advice to patients with abnormal colour vision and is often used for occupational selection when reliable recognition of surface colour codes is required. However, there has been only one previous study of the correlation between performance at the D15 test and the naming of surface colour codes and there has been no study of whether a person who passes the D15 can reliably name surface colours. Methods: One hundred and two people aged 11 to 65 years with abnormal colour vision were recruited from consecutively presenting optometric patients and were asked to name the colours of fabric, paint and cotton thread samples. There were 10 colours in each class of material and the samples were presented in a large (five to 10 degree angular subtense) and small size (2.5 deg and a single thread). The errors made were compared to those made by an age‐matched control group of equal size with normal colour vision. Results: The correlations between the Farnsworth D15 colour confusion index and colour naming errors were 0.62 for the large stimuli and 0.73 for the small stimuli. Its sensitivity and specificity identifymg those who made more errors than the worst performing colour normal person were 0.80 and 0.69 (large stimuli) and 0.75 and 0.71 (small stimuli). A Nagel anomaloscope range of less than 35 scale units provides essentially the same sensitivity and specificity. Conclusions: About 40 per cent of those with abnormal colour vision can name the main colours correctly under good visibility conditions. The D15 test is an imperfect predictor of those who can name surface colour codes correctly but it does provide useful information for general counselling. It is not suitable as a single test for occupational selection because it will pass 20 per cent who cannot name surface colours correctly and fail 30 per cent who can. In occupations in which recognition of surface colour codes is of critical importance, it may be best not to select people with abnormal colour vision because of the lack of a colour vision test that is a perfect predictor of the ability to recognise surface colours.  相似文献   
13.
[目的]探讨宫血宁胶囊对月经过多患者的临床效果。[方法]对月经过多的患者通过使用宫血宁胶囊前后的经量、血色素比较分析。[结果]20例月经过多患者使用宫血宁胶囊后经量明显减少、血色素有提高。[结论]宫血宁胶囊治疗月经过多临床效果显著。  相似文献   
14.
对150名有机磷农药作业工人进行了心电图检查,结果表明,有机磷农药作业工人心电图异常发生率极显著高于对照组(P<0.001)。主要改变为窦性心动过缓,窦性心律不齐,ST—T异常,说明心电图与异常接触有机磷衣药有关,应加强防护措施。  相似文献   
15.
Abstract We investigated factors correlated with abnormal behavior in the elderly residing in a special nursing home (group A) and a psychiatric hospital (group B) using the dementia behavior disturbance scale, the mini mental state examination, the Japanese version of the Philadelphia Geriatric Center morale scale, and the ADL assessment scale. The cognitive function of group B was decreased compared with that of group A, but most activities of daily living (ADL) in the latter group were disrupted compared with those in the former. Only a few categories of ADL correlated with abnormal behavior in group A, whereas cognitive function, quality of life, and most categories of ADL correlated with abnormal behavior in group B. These results suggest that factors correlated with abnormal behavior in the elderly differ within institutions of medical and social welfare systems.  相似文献   
16.
17.
Background: People with abnormal colour vision often report difficulty seeing coloured berries and flowers in foliage, which suggests they will have a diminished capacity for visual search when target objects are marked out by colour. There is very little experimental evidence of the effect of abnormal colour vision on visual search and none relating to search for objects in natural foliage. Method: We showed 79 subjects with abnormal colour vision (seven protanopes, 10 deuteranopes, 16 protanomals and 46 deuteranomals) and 20 subjects with normal colour vision photographs of natural scenes and asked them to locate clumps of red berries, to trace the length of a red string on grass and to name the season depicted in a photograph taken in the Autumn and the same scene photographed in the Summer. Colour vision was assessed using the Ishihara, the Medmont C100, the Farnsworth D15, the Richmond HRR and the Nagel anomaloscope. Results: All the subjects with abnormal colour vision located fewer clumps of red berries than those with normal colour vision. The subjects who failed the Farnsworth D15 performed significantly worse than those who passed but the distribution of scores in the two groups overlaps. The majority of subjects with abnormal colour vision could not trace the full length of the string: only 38 per cent of anomalous trichromats who passed the Farnsworth D15 test and three per cent of those who failed it were able to trace the full length of the string. Fifty‐five per cent of those classed as having a mild deficiency by the HRR test could trace the whole string. Most dichromats were unable to identify the Autumn season and those who did may have been assisted by guessing. Most (94 per cent) of those who passed the Farnsworth D15 test and all those classified as having a ‘mild’ deficiency by the HRR test could identify the season. Conclusions: All people with abnormal colour vision, even those with a very mild deficiency, have some degree of impairment of their ability to see coloured objects in natural surroundings. A pass at the Farnsworth D15 test or a ‘mild’ classification with the Richmond HRR test identifies those likely to have the least problems with visual search and identification tasks. The results have practical implications for the selection of personnel in occupations that involve visual search in natural terrain.  相似文献   
18.
应用与凝血酶原及异常凝血酶原有免疫交叉反应的非Ca(Ⅱ)依赖性抗人凝血酶原抗体,建立夹心BA-ELISA法,检测人血浆凝血酶原的最低浓度可达1ng/ml。血浆经皂土和柠檬酸钡吸附处理,除去纤维蛋白原和凝血酶原后,可用本法检出存留于血浆中的微量异常凝血酶原,并测得健康人血浆异常凝血酶原的均值为74.61±19.43ng/ml。本法操作简便,特异性强,重复性好。  相似文献   
19.
We report on 2 unrelated Brazilian girls, born to nonconsanguineous parents, and presenting structural central nervous system defects, hydrocephaly, macrocephaly, craniosynostosis, prominent forehead, anophthalmia, and abnormal nares. These patients may have a previously undescribed recurrent-pattern cerebro-oculo-nasal syndrome. © 1993 Wiley-Liss, Inc.  相似文献   
20.
Abstract. Objectives. To evaluate lipids and lipoproteins as risk factors for coronary heart disease (CHD) in older men with non-insulin-dependent diabetes (NIDDM) or abnormal glucose tolerance compared with normoglycaemic men. Design. A prospective, population-based cohort study based on the lipoprotein examination (1970–72) of the Honolulu Heart Program. Follow-up was through to December 1988. Setting. Honolulu, Hawaii. Subjects. Japanese-American men, ages 51–72 at baseline: 2042 with 1 h glucose < 12.5 mmol l?1 (normal group); 376 on oral hypoglycaemic agents or with 1 h glucose ≥ 12.5 mmol l?1 after 50 g oral glucose challenge (abnormal glucose tolerance group). None had prevalent coronary heart disease (CHD) or stroke at baseline. Main outcome measures. Incident CHD: definite nonfatal myocardial infarction (MI) or fatal CHD. Results. There were 221 incident cases in the normal group, and 65 in the abnormal glucose tolerance group. Total and high-density lipoprotein (HDL) cholesterol were significant predictors of incident CHD in men with NIDDM or abnormal glucose tolerance after controlling for age, body-mass index, systolic blood pressure, pack-years of cigarettes and alcohol consumption (P < 0.05). Total, low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL) cholesterol were significant predictors in normal men, and HDL cholesterol was of borderline significance. Conclusions. Abnormal lipids and lipoproteins are significant, independent predictors of CHD in subjects with NIDDM or abnormal glucose tolerance. Attention to lipid and lipoproteins as CHD risk factors should be part of clinical management of these patients.  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