全文获取类型
收费全文 | 9259篇 |
免费 | 612篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 53篇 |
儿科学 | 269篇 |
妇产科学 | 239篇 |
基础医学 | 1027篇 |
口腔科学 | 426篇 |
临床医学 | 1023篇 |
内科学 | 1746篇 |
皮肤病学 | 101篇 |
神经病学 | 826篇 |
特种医学 | 428篇 |
外科学 | 1273篇 |
综合类 | 430篇 |
一般理论 | 11篇 |
预防医学 | 980篇 |
眼科学 | 176篇 |
药学 | 468篇 |
1篇 | |
中国医学 | 22篇 |
肿瘤学 | 380篇 |
出版年
2022年 | 50篇 |
2021年 | 138篇 |
2020年 | 72篇 |
2019年 | 126篇 |
2018年 | 138篇 |
2017年 | 114篇 |
2016年 | 116篇 |
2015年 | 158篇 |
2014年 | 193篇 |
2013年 | 313篇 |
2012年 | 435篇 |
2011年 | 454篇 |
2010年 | 271篇 |
2009年 | 231篇 |
2008年 | 394篇 |
2007年 | 431篇 |
2006年 | 395篇 |
2005年 | 391篇 |
2004年 | 371篇 |
2003年 | 344篇 |
2002年 | 345篇 |
2001年 | 286篇 |
2000年 | 277篇 |
1999年 | 255篇 |
1998年 | 116篇 |
1997年 | 104篇 |
1996年 | 101篇 |
1995年 | 86篇 |
1994年 | 93篇 |
1993年 | 78篇 |
1992年 | 222篇 |
1991年 | 215篇 |
1990年 | 233篇 |
1989年 | 198篇 |
1988年 | 218篇 |
1987年 | 217篇 |
1986年 | 190篇 |
1985年 | 197篇 |
1984年 | 103篇 |
1983年 | 101篇 |
1982年 | 74篇 |
1981年 | 67篇 |
1980年 | 63篇 |
1979年 | 83篇 |
1978年 | 82篇 |
1977年 | 55篇 |
1976年 | 55篇 |
1974年 | 59篇 |
1972年 | 59篇 |
1971年 | 65篇 |
排序方式: 共有9879条查询结果,搜索用时 15 毫秒
31.
1. Evidence that vegetarian dietary patterns lower blood pressure (BP) comes from both population studies and randomized controlled trials in normotensive and hypertensive subjects. 2. The effect has been shown most clearly in those who keep to a strict lacto-ovo vegetarian diet characterized by a relatively low intake of saturated fat, a high polyunsaturated/saturated fat ratio, and a high intake of fruit, vegetables and other fibre containing products. Randomized controlled dietary trials suggest the effects are independent of dietary sodium, additive to that of calorie restriction, and not due to the absence of meat protein per se. Indeed, recent population studies suggest an inverse relationship between dietary protein and BP. 4. Dietary fats, fibre, potassium, magnesium and calcium do not independently seem to account for the effects. A possible role for complex carbohydrate in conjunction with the other dietary factors has yet to be fully explored. 相似文献
32.
High-dose gadoteridol in MR imaging of intracranial neoplasms. 总被引:6,自引:0,他引:6
V M Runge J E Kirsch V J Burke A C Price K L Nelson G S Thomas B L Dean C Lee 《Journal of magnetic resonance imaging : JMRI》1992,2(1):9-18
Twelve patients with a high suspicion of brain metastases by previous clinical or radiologic examinations were studied in a phase III investigation with magnetic resonance (MR) imaging at 1.5 T after a bolus intravenous injection of 0.1 mmol/kg gadoteridol followed at 30 minutes by a second bolus injection of 0.2 mmol/kg gadoteridol. All lesions were best demonstrated (showed greatest enhancement) at the 0.3-mmol/kg (cumulative) dose, with image analysis confirming signal intensity enhancement in the majority of cases after the second gadoteridol injection. More lesions were detected with the 0.3-mmol/kg dose than with the 0.1-mmol/kg dose, and more lesions were detected with the 0.1-mmol/kg dose than on precontrast images. In this limited clinical trial, high-dose gadoteridol injection (0.3-mmol/kg cumulative dose) provided improved lesion detection on MR images specifically in intracranial metastatic disease. 相似文献
33.
Aaron R. Folsom Timothy C. Cook J. Michael Sprafka Gregory L. Burke Stephan W. Norsted David R. Jacobs Jr. 《Journal of behavioral medicine》1991,14(1):1-9
Energy expenditure in leisure-time physical activity (LTPA) was measured using the Minnesota LTPA Questionnaire in 35- to 74-year-old black and white residents of Minneapolis-St. Paul, Minnesota. Estimates of the geometric mean LTPA energy expenditure were 129 and 204 kcal per day for black and white men (p<.05) and 91 and 123 kcal per day for black and white women (p<.05). The percentage of individuals expending 2000 kcal or more per week in LTPA was significantly lower in black men than white men (25 vs. 35%; p=.01) but was not different in black versus white women (18 vs. 17%). Although black men and women reported greater occupational physical activity than their white counterparts, LTPA and job activity were unrelated in all race and sex groups. In both races, LTPA energy expenditure declined with age. LTPA increased with level of formal education, and the largest LTPA difference between blacks and whites was observed in those who had a high-school diploma or less. Blacks had lower participation rates than whites in most of the individually assessed physical activities. Additional research is needed on the determinants and promoters of LTPA in population subgroups.The research was funded by National Heart, Lung, and Blood Institute Research Grant R01 HL 23727 and National Research Award T32 HL 07328-10. 相似文献
34.
Hairy cells and monocytoid B lymphocytes: are they related? 总被引:5,自引:0,他引:5
The normal tissue counterpart of hairy cell leukemia is unknown. Because of the morphologic similarities of hairy cells to reactive and lymphomatous monocytoid cells, we compared the phenotypic characteristics of seven spleens involved by hairy cell leukemia with four reactive lymph nodes containing benign monocytoid B cells and three lymph nodes diagnosed as monocytoid B cell lymphoma. The hairy cells had a phenotype of surface Ig+, B1/Leu-14+, Leu-M5+, PCA-1+, Tac+, B2-, BA-1-, BA-2-, J5-, T10-, T11-, Leu-1-, Leu-2a-, Leu-3a-. The immunophenotype of both the reactive and neoplastic monocytoid B lymphocytes was virtually identical to the hairy cells. The major difference was that monocytoid B cells failed to react with anti-Tac and that PCA-1 expression was inconsistent. Despite these variances, the immunophenotypic similarities are remarkable, particularly the common expression of B1/Leu-14 and Leu-M5 (S-HCL3), and suggest a possible lineage relationship between hairy and monocytoid B cells. 相似文献
35.
The overall consensus of the Work Group was that the workshop provided an excellent opportunity for discussion of the scientific issues pertaining to non-occupational exposures to gasoline as it related to public health officials, legal and regulatory agencies, and industrial (workplace) concerns. It was enlightening to discuss the implications of new and existing data and methods for determining the public's exposure to gasoline. The workshop resulted in a list of data needs and a vision of the future research that will be required to aid future users of exposure data. 相似文献
36.
E Shmueli M F Myszor D Burke C O Record K Matthewson 《The British journal of surgery》1992,79(8):778-780
Of 86 patients with inoperable malignant dysphagia, 68 (79 per cent) underwent successful palliation by endoscopic laser therapy, of whom 24 remained well palliated until the time of death. In 18 patients laser treatment was unsuccessful and nine of these underwent intubation, eight successfully. After successful laser therapy, dysphagia recurred in 44 patients a mean of 7.8 weeks later. Of these, 31 received palliation until death by dilatation with or without laser therapy, and 13 required intubation. The overall laser-related complication rate was 12 per cent with a mortality rate of 4 per cent. The intubation-related mortality rate was 9 per cent. 相似文献
37.
Smoking in Pregnancy and Parenthood: What is the Role of Depression, Anxiety and Nicotine Addiction?
Leona Bull Ronan Burke Siobhan Walsh Emma Whitehead 《Early child development and care》2003,173(2):349-356
This paper presents some of the findings from the Smoking in Pregnancy study of attitudes towards smoking among pregnant women, mothers of young children and their partners in East Surrey. As part of the study, respondents completed a General Health Questionnaire to identify mental health difficulties and, if they were smoking at the time of the study, they also completed the Fagerstrom nicotine addiction test. Eleven female respondents had high scores on the General Health Questionnaire, suggesting symptoms of depression, anxiety and/or social dysfunction for these women. There was no evidence that smokers were suffering from greater mental health difficulties than ex-smokers or non-smokers. However, the General Health Questionnaire scores of smokers were positively associated with their level of nicotine dependence. Furthermore, when General Health Questionnaire scores of all respondents were compared with self-reported health status there was a marked discrepancy suggesting under-reporting of symptoms by women. 相似文献
38.
A kinetic study of leucine metabolism in severely burned patients. Comparison between a conventional and branched-chain amino acid-enriched nutritional therapy.
下载免费PDF全文
![点击此处可从《Annals of surgery》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A cross-over design study was used to examine the metabolic consequences of enteral feeding for 48 to 96 hours with either a branched-chain amino acid (BCAA)-enriched (44% BCAA) or a conventional egg protein formulation in 12 severely burned adult patients. A stable isotope labeled leucine (L-1-13C-leucine) tracer approach was used to measure leucine flux and oxidation and to estimate rates of whole body protein synthesis and breakdown. Additionally, 15N2-urea and 6,6-2H-glucose were administered to assess the status of urea and glucose kinetics with these two nutritional treatments. Average patient age was 54 years, and average burn surface area was 36%. Studies were conducted at an average of 25 days postburn. Leucine flux and oxidation were significantly (p less than 0.01, by paired t-test) elevated with BCAA feeding as compared to the egg protein formulation. However, there were no significant differences in the rates of leucine incorporation into, or release from, proteins (p greater than 0.05) between the two dietary periods. Mean rates of body protein synthesis and breakdown for each diet were about twice the rates reported for healthy young adults. Apparent nitrogen balance measurements were not statistically different (p greater than 0.1) between the two diet periods. Furthermore, urea and glucose kinetics failed to show significant differences between the two diet periods. It appears from these results that the major consequences of increased intake of leucine from the BCAA formula is an enhanced rate of leucine oxidation. In conclusion, (1) the availability of BCAAs is not rate-limiting for enhanced protein synthesis in burn patients, and (2) the use of enriched BCAA formulas in burn therapy does not appear to offer advantages over a routinely used enteral egg protein formula, at least based on the present determinations. 相似文献
39.
Jonathan M Hodgson Kevin D Croft Trevor A Mori Valerie Burke Lawrence J Beilin Ian B Puddey 《The Journal of nutrition》2002,132(1):55-58
Prospective studies suggest that tea may protect against cardiovascular disease. A potential mechanism for such an effect involves inhibition of lipid peroxidation by polyphenolic antioxidants derived from tea. Our objective was to determine whether regular ingestion of tea could inhibit in vivo lipid peroxidation. Two controlled intervention studies assessed the effects of regular ingestion of tea on lipid peroxidation determined by measurement of urinary F(2)-isoprostane excretion. Study 1: The effects of 1000 mL/d of green tea and black tea were compared with hot water containing caffeine in 13 subjects with elevated blood pressure using a randomized 3-period (7 d each) crossover design. Study 2: The effects of 1250 mL/d of black tea were compared with hot water in 22 subjects with mildly raised serum total cholesterol concentrations using a randomized 2-period (4 wk each) crossover design. F(2)-isoprostane excretion was not altered after regular ingestion of green tea (273 +/- 48 pmol/mmol creatinine) or black tea (274 +/- 39 pmol/mmol creatinine) in comparison with hot water (263 +/- 47 pmol/mmol creatinine; Study 1), or by regular ingestion of black tea (334 +/- 71 pmol/mmol creatinine) in comparison with hot water (355 +/- 75 pmol/mmol creatinine; Study 2). These results do not support the suggestion that polyphenolic antioxidants derived from tea inhibit in vivo lipid peroxidation. 相似文献
40.