全文获取类型
收费全文 | 3210篇 |
免费 | 164篇 |
国内免费 | 111篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 69篇 |
妇产科学 | 48篇 |
基础医学 | 249篇 |
口腔科学 | 39篇 |
临床医学 | 227篇 |
内科学 | 710篇 |
皮肤病学 | 14篇 |
神经病学 | 109篇 |
特种医学 | 19篇 |
外科学 | 157篇 |
综合类 | 257篇 |
预防医学 | 1114篇 |
眼科学 | 4篇 |
药学 | 158篇 |
1篇 | |
中国医学 | 123篇 |
肿瘤学 | 177篇 |
出版年
2023年 | 76篇 |
2022年 | 152篇 |
2021年 | 207篇 |
2020年 | 138篇 |
2019年 | 153篇 |
2018年 | 156篇 |
2017年 | 88篇 |
2016年 | 99篇 |
2015年 | 93篇 |
2014年 | 283篇 |
2013年 | 236篇 |
2012年 | 163篇 |
2011年 | 211篇 |
2010年 | 135篇 |
2009年 | 158篇 |
2008年 | 161篇 |
2007年 | 160篇 |
2006年 | 111篇 |
2005年 | 96篇 |
2004年 | 74篇 |
2003年 | 41篇 |
2002年 | 43篇 |
2001年 | 44篇 |
2000年 | 33篇 |
1999年 | 24篇 |
1998年 | 21篇 |
1997年 | 25篇 |
1996年 | 23篇 |
1995年 | 22篇 |
1994年 | 16篇 |
1993年 | 14篇 |
1992年 | 27篇 |
1991年 | 16篇 |
1990年 | 22篇 |
1989年 | 13篇 |
1988年 | 14篇 |
1987年 | 14篇 |
1986年 | 5篇 |
1985年 | 17篇 |
1984年 | 15篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1973年 | 5篇 |
1971年 | 4篇 |
排序方式: 共有3485条查询结果,搜索用时 31 毫秒
61.
Esteve Fernandez Carlo La Vecchia Barbara D'Avanzo Claudia Braga Eva Negri Silvia Franceschi 《European journal of epidemiology》1997,13(3):267-273
To describe the relationship between sociodemographic factors, life-style habits, selected dietary indicators, smoking-related variables, and quitting smoking we analyzed data derived from the comparison group of a case-control study of colorectal and breast cancers based on a network of teaching and general hospitals in Northern Italy. A total of 2621 subjects (1215 women and 1406 men) who were ever cigarette smokers were included for analysis. Age-adjusted rates of stopping smoking (quit rates) and multivariate odds ratios (OR) of quitting smoking were computed. The overall age-adjusted quit rate was 38.6% for males and 24.9% for females, corresponding to an OR of quitting of 0.6 (95% CI: 0.5–0.7) for females vs males. The quitting rate increased with increasing age. After allowing for age, smoking cessation was more frequently reported by more educated or higher social class individuals. No relationship was present between quitting smoking and alcohol consumption, but quitting smoking was inversely related to coffee consumption. The probability of quitting smoking increased directly with number of cigarettes among males but not among females, who showed a J-shaped pattern. Older, heavy smokers were more likely to give up smoking. A general pattern of increasing rates of quitting smoking with higher consumption of vegetables and fruit, and hence -carotene, was present. This study confirms a positive association between quitting smoking and increasing age, higher education, low coffee consumption, heaviness of smoking and high consumption of vegetables and fruit. 相似文献
62.
Plasma levels of antioxidant vitamins and cholesterol in a large population sample in Central-Northern Italy 总被引:2,自引:0,他引:2
D. Palli A. Decarli A. Russo F. Cipriani A. Giacosa D. Amadori R. Salkeld S. Salvini E. Buiatti 《European journal of nutrition》1999,38(2):90-98
Background:
In a population-based multicenter case-control study of diet, life-style, and gastric cancer a large series of adults, aged
30–75 years (mean 58.9 yearss), were randomly sampled from the general population in 3 areas of Central-Northern Italy.
Aim of the study: To evaluate the relationship between plasma levels of antioxidant vitamins and cholesterol, and sociodemographic characteristics,
life-style factors, and dietary intake of selected nutrients in a sample of the Italian population.
Methods: A fasting blood sample was available for 945 subjects (553 men, 392 women). The plasma concentrations of ascorbic acid,
carotene, retinol, alpha-tocopherol, and cholesterol were determined by a centralized laboratory. All participants answered
to a detailed questionnaire collecting information on sociodemographic and anthropometric characteristics, smoking, alcohol
drinking, and dietary habits. Covariance analysis models, with post hoc Dunnett tests, including terms for age, sex, study
center, and period of blood drawing, were used for selected multiple-way comparisons of mean values of plasma nutrients.
Results: Mean plasma values of retinol were higher among men while women had higher levels of plasma carotene, ascorbic acid, alpha-tocopherol,
and cholesterol. Plasma carotene levels showed an inverse association with body mass index, alcohol consumption, and smoking
and a positive association with social class. Carotene concentrations were higher in plasma samples obtained in spring/summer,
while ascorbic acid levels were higher in autumn/winter. Partial correlation coefficients between carotene and ascorbic acid
(0.69 in men; 0.74 in women), between carotene and alpha-tocopherol (0.44; 0.37), and between alpha-tocopherol and ascorbic
acid (0.45; 0.41). Plasma alpha-tocopherol and retinol correlated with plasma cholesterol. On the other hand, plasma carotene
and ascorbic acid were correlated with their estimated dietary intakes, while the intakes of other nutrients, as expected,
correlated rather poorly with the respective plasma concentrations.
Conclusions: Socio-economic factors, life-style, and specific nutrient intake, in addition to gender, are related to nutrient plasma
levels in Italian adults and may provide specific suggestions for the prevention of chronic diseases.
Received: 8 December 1998, Accepted: 25 February 1999 相似文献
63.
F.J. Sanchez-Muniz S. Bastida J.M. Viejo A.H.M. Terpstra 《European journal of nutrition》1999,38(1):20-27
Summary In order to investigate the effect of a short-term application of marine n-3 polyunsaturated fatty acids on the composition
of serum very low density lipoproteins (VLDL), low density lipoproteins (LDL), and high density lipoproteins (HDL), nine women
aged 29±4.2 years, following a diet with a SFA/MUFA/PUFA profile of 2.4/3/1, received supplements of six capsules daily, each
capsule containing 0.137 g of n-3 fatty acids (14.5% eicosapentaenoic acid (EPA) and 8.9% docosahexaenoic acid (DHA)) for
10 d. Food consumption, assessed during two 10-days periods indicates that percentage contribution of SFA, MUFA, and PUFA
to the daily energy intake did not change through the fish-oil supplementation period, but the daily consumption of n-3 fatty
acids increased 2.3 times. N-3 fatty supplementation increased EPA and DHA percentages in serum phospholipids, but failed
to decrease (p>0.05) the cholesterol and triglyceride concentration in serum LDL and HDL, although it did so in VLDL. In contrast,
the lipoprotein-phospholipid and lipoprotein-protein concentrations were markedly affected, mainly in LDL and HDL (at least
p<0.01). HDL and VLDL compositions were not affected but the total mass (lipid+protein in mg/dl) concentration of these lipoproteins
significantly decreased (p<0.05), suggesting a lower number of these particles in circulating blood after the n-3 treatment.
The LDL-cholesterol/LDL-apolipoprotein B ratio increased (p<0.01) reflecting a probable increase in LDL size. Following fish
oil supplementation, LDL particles contained a significantly lower amount of phospholipids, which also suggests changes in
the surface/core ratio of the average LDL. Changes in serum lipoprotein lipids did not significantly correlate with any dietary
change other than the n-3 fatty acid increase. The results indicate that a 10-day application of a small supplement of n-3
change the LDL composition leading to less atherogenic LDL particles with lower phospholipid and apolipoprotein (Apo) B concentrations.
Received: 15 May 1998, Accepted: 28 August 1998 相似文献
64.
《Auris, nasus, larynx》2022,49(6):986-994
ObjectiveDysphagia is a common symptom in Parkinson's disease (PD) and it represents a negative prognostic factor because of its complications. This study is to evaluate pharyngeal dysphagia for boluses of various consistencies with Fiberoptic Endoscopic Evaluation of Swallowing (FEES) and Pharyngeal High-Resolution Manometry (PHRM) in a group of PD patients, making a comparison between the information provided by the two exams.MethodsGroup of 20 patients affected by PD was selected and initially subjected to a qualitative evaluation of the swallowing performing FEES. Subsequently, they were evaluated by PHRM to identify quantitative measures associated with pressures expressed by pharyngeal organs during swallowing. Values obtained in the study group were compared with those recorded in a group of 20 healthy subjects.ResultsStudy showed that Pmax (the maximum pressure elicited by the single pharyngeal muscle structures involved in swallowing) was significantly lower than the control group (p<0.05) for all the boluses and consistency tested, in particular for the Tongue base and the Cricopharyngeal muscle. Pmean pre-swallowing pressure (represents the mean value of a contraction in which basal and maximal pressure where normally calculated) was significantly higher compared to normal subjects for the Tongue base and the Cricopharyngeal muscle (p<0.05). Mean intra-swallowing pressure was higher for the Velopharynx and the Cricopharyngeal muscle, but lower for the tongue base. Pmax and Pmean at PHRM were altered independently to the degree of dysphagia detected at FEES, and they did not correlate either with the location of the residue or with the type of bolus. Images displayed at the FEES, found the corresponding biomechanical explanations in the PHRM, which also allowed us to quantify the extent of the dysfunction, through the calculation of the pressures generated in the various structures studied.ConclusionPHRM is particularly useful in the early detection of dysphagia, when FEES may still show no evidence of abnormal swallowing. 相似文献
65.
Nutrition and laryngeal cancer 总被引:3,自引:0,他引:3
The main etiologic factors of cancers of the larynx and hypopharynx are alcohol and tobaeco, and their prevalence in different populations explains, to a large extent, the wide variations in incidence observed around the world. Besides these two main risk factors, however, diet also seems to play a role in determining the risk of these cancers. There is consistent evidence that low consumption of fruit and vegetables is associated with higher risk, after statistical adjustment for alcohol and tobacco. Consumption of vegetable oils and fish and a moderately high polyunsaturated/saturated fatty acid ratio (P/S ratio) were reported to be associated with reduced risk. Low intake of vitamin C, -carotene and vitamin E were reported consistently to be associated with higher laryngeal cancer risk, but there was no clear evidence that these micronutrients are better predictors of cancer risk than the principal food groups from which their intake levels were estimated, i.e., fruits, vegetables, vegetable oils, and fish. Given the overwhelming role of tobacco and alcohol in the etiology of these cancers and the extremely low incidence among nonsmokers/nondrinkers, the available studies provide no estimate of the role of diet in subjects not exposed to these factors. The evidence indicates, however, that, in the presence of tobacco and/or alcohol, low intake of fruit and vegetables may account for 25 to 50 percent of the cases among men. 相似文献
66.
Leif Aringer Agneta Löf Carl-Gustaf Elinder 《International archives of occupational and environmental health》1991,63(5):341-346
Summary The excretion of thioethers was measured in the urine of 6 volunteers, who were experimentally exposed to styrene, and 18 styrene workers. In addition, 12 clerks (non-smokers) and 12 sheet-metal workers (smokers) served as control groups. Diet was standardized during the experiments. Thioethers were measured by a spectrophotometric method. The volunteers were exposed to styrene, 210 mg/m3, for 2 h at a 50-W workload. An increase in thioether excretion was observed; the largest was in the urine samples collected between 0.5 and 5 h after the end of the exposure. After 43 h the excretion of thioethers was close to the preexposure level (3.5 mmol/mol creatinine). About 1% of the styrene absorbed was detected as thioethers in urine, which is only about 1/10 of the conversion reported for rats. From excretion rate curves a half-life of about 11 h was calculated for styrene thioethers. The styrene workers were employed at two plants. The average exposure to styrene (time-weighted average 8 h) was estimated to be about 115 mg/m3 (smokers in plant A), 55 mg/m3 (non-smokers in plant A) and 10 mg/m3 (non-smokers in plant B). The excretion of thioethers in exposed workers at plant A was higher by 2–4 mmol/mol creatinine than that in non-exposed controls. In plant B, where exposure was lower, an increase in that amount of thioethers excreted in the urine by exposed workers was less pronounced, and was statistically significant only when post-shift samples were compared with pre-shift samples. The results of the present study indicate that control samples should be collected both from non-exposed groups and from the exposed individuals before work shifts, to improve the likelihood of detecting genotoxic exposure in the work environment. 相似文献
67.
Hideki Nagano Shigekazu Ohyama Yoshihiro Sakamoto Keiichiro Ohta Toshiharu Yamaguchi Tetsuichiro Muto Akio Yamaguchi 《Gastric cancer》2004,7(1):54-59
Background Pylorus-preserving gastrectomy (PPG) and transverse gastrectomy (TrG) have been accepted as function-preserving procedures for node-negative early gastric cancer. It is believed that a better quality of life is guaranteed after PPG or TrG compared to that after distal subtotal gastrectomy (DSG) with Billroth type-I reconstruction. However, objective evaluations of the gastric remnant following gastrectomy have not been widely reported, and the real advantages and disadvantages of PPG or TrG over DSG remain unclear. Moreover, the risk of secondary cancer after PPG or TrG is uncertain.Methods Between 1991 and 2000, 834 DSGs were carried out in our institute for preoperatively diagnosed patients with early gastric cancer. The degree of residual gastritis and the amount of diet residue in the gastric remnant were evaluated by annual gastrointestinal endoscopic investigations prospectively for 72 patients after PPG, 95 patients after TrG, and 60 patients after DSG. These analyses were performed using the RGB classification (residue, gastritis, bile). The incidence of disease greater than or equal to grade 2 was calculated, and the time trends of the incidence for each procedure were also studied for 3 years after gastrectomy. In addition, secondary cancer cases in the gastric remnant mucosa were checked for each procedure during this period, and the incidence of secondary cancer after each operation was calculated.Results The incidence of gastritis, of grade 2 or more, found in the gastric remnant was significantly lower after PPG (1.4%) and TrG (2.1%) than after DSG (43.3%). However, the incidence of moderate or greater residue in the gastric remnant, grade 2 or more, was significantly higher after PPG (45.8%) and TrG (40.0%) than after DSG (11.7%). The analysis of time trends of gastritis and diet residue reflected the significant advantage or disadvantage for each procedure 1 year after surgery. The analysis also included these factors without consideration of elapsed time following surgery. Two patients after PPG (2.8%) and three patients after TrG (3.2%) developed secondary cancer in the gastric remnant. No DSG-treated patient showed new cancer genesis in the remaining stomach.Conclusion PPG and TrG have the advantage over DSG in preventing postoperative gastritis in the gastric remnant. On the other hand, moderate or greater diet residue in the gastric remnant is more common after PPG or TrG than after DSG. For the risk of carcinogenesis in the remnant gastric mucosa, we could not conclude that there was any apparent difference between these range-limited gastrectomies and conventional DSG. Further study is necessary to determine the significant advantages and disadvantages of using PPG or TrG. 相似文献
68.
M. Rosaria Galanti Lisbeth Hansson Reinhold Bergström Alicja Wolk Anette Hjartåker Eiliv Lund Lars Grimelius Anders Ekbom 《Cancer causes & control : CCC》1997,8(2):205-214
A population-based case-control study was conducted in two regions ofSweden and Norway to investigate the association between dietary habits andthe risk of thyroid cancer. The consumption of selected foods was reported ina self-completed food-frequency questionnaire by 246 cases withhistologically confirmed papillary (n = 209) and follicular (n = 37) thyroidcarcinoma, and 440 age- and gender-matched controls. Odds ratios (OR) andtheir 95 percent confidence interval (CI) were calculated as estimates of therelative risk using conditional logistic regression. High consumption ofbutter (OR = 1.6, CI = 1.1-2.5) and cheese (OR = 1.5, CI = 1.0-2.4) wasassociated with increased risks. Residence in areas of endemic goiter inSweden was associated with an elevated risk, especially among women (OR =2.5, CI = 1.3-4.9). High consumption of cruciferous vegetables was associatedwith increased risk only in persons who ever lived in such areas. A decreasedrisk was associated with consumption of iodized salt in northern Norway, andwith use of iodized salt during adolescence among women (OR = 0.6, CI =0.6-1.0). The results of this study suggest a role of diet and environment inthe risk of thyroid cancer. 相似文献
69.
老年人膳食维生素K1摄入量及其主要来源 总被引:2,自引:0,他引:2
目的 :了解老年人膳食中维生素 K1 的摄入量和主要来源。方法 :对 113名 6 0岁以上老年人进行 7d膳食记录。用国内文献发表的食物中维生素 K1 含量资料和英国食物中维生素 K1 含量资料计算膳食中维生素 K1 摄入量。对所有食物按绿叶蔬菜、其它蔬菜、水果、油脂类、粮谷类、奶及蛋类、鱼肉类及其它食物进行分类 ,分别统计得出每类食物的维生素 K1含量。结果 :该人群膳食维生素 K1 摄入量为 347± 182 μg/天 ,膳食中维生素 K1 的主要来源是绿叶蔬菜占 82 % ,食用油脂占11%。菠菜、韭菜和大白菜是绿叶蔬菜中提供维生素 K1 的主要来源 ,占绿叶蔬菜提供维生素 K1 的 82 %。结论 :本研究中的老年人膳食维生素 K1 摄入量较高。多食绿叶蔬菜和植物油可提高人群膳食维生素 K1 摄入量。 相似文献
70.
[目的 ]探讨饮食控制对中老年糖耐量减低 (IGT)者血糖、血脂的影响。 [方法 ] 2 0 0 1年在广州市对 42例中老年IGT患者进行为期 10个月的饮食控制 ,于饮食控制前后分别测定空腹血糖 (FSG)、餐后 2小时血糖 (PSG)、血清甘油三酯(TG)、总胆固醇 (TC)、胰岛素 (INS)、体重指数 (BMI)、糖化低密度脂蛋白 (G LDL)和红细胞内游离钙 [红细胞 (Ca2 )i]。[结果 ]饮食控制后 ,IGT患者FSG、PSG、TG、TC、INS、BMI、G LDL、红细胞 (Ca2 )i水平均较控制前下降 (P <0 0 1)。 [结论 ]饮食控制可明显改善IGT患者的糖与脂代谢 相似文献