全文获取类型
收费全文 | 2057篇 |
免费 | 154篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 67篇 |
妇产科学 | 36篇 |
基础医学 | 320篇 |
口腔科学 | 41篇 |
临床医学 | 160篇 |
内科学 | 508篇 |
皮肤病学 | 60篇 |
神经病学 | 209篇 |
特种医学 | 39篇 |
外科学 | 213篇 |
综合类 | 7篇 |
一般理论 | 2篇 |
预防医学 | 125篇 |
眼科学 | 38篇 |
药学 | 151篇 |
中国医学 | 13篇 |
肿瘤学 | 226篇 |
出版年
2024年 | 4篇 |
2023年 | 15篇 |
2022年 | 32篇 |
2021年 | 69篇 |
2020年 | 39篇 |
2019年 | 68篇 |
2018年 | 77篇 |
2017年 | 52篇 |
2016年 | 72篇 |
2015年 | 56篇 |
2014年 | 84篇 |
2013年 | 113篇 |
2012年 | 147篇 |
2011年 | 183篇 |
2010年 | 82篇 |
2009年 | 90篇 |
2008年 | 155篇 |
2007年 | 159篇 |
2006年 | 122篇 |
2005年 | 120篇 |
2004年 | 92篇 |
2003年 | 92篇 |
2002年 | 71篇 |
2001年 | 31篇 |
2000年 | 19篇 |
1999年 | 22篇 |
1998年 | 15篇 |
1997年 | 13篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 2篇 |
1992年 | 9篇 |
1991年 | 16篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1981年 | 3篇 |
1979年 | 5篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1970年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有2225条查询结果,搜索用时 31 毫秒
21.
Silvio Buscemi Carola Buscemi Davide Corleo Giovanni De Pergola Rosalia Caldarella Francesco Meli Cristiana Randazzo Salvatore Milazzo Anna Maria Barile Giuseppe Rosafio Valentina Settipani Sabina Gurrera Antonio Maria Borzì Marcello Ciaccio 《Nutrients》2021,13(6)
Background: Vitamin D plays a pivotal role in calcium and phosphorus metabolism, also influencing bone tissue. Several studies have reported that vitamin D blood levels were significantly lower in people with obesity, probably due to its uptake by the adipose tissue. Clinical studies that investigated the changes of circulating levels of vitamin D following weight loss reported controversial data. A very low-calorie ketogenic diet is acknowledged as a reliable treatment to achieve a rapid weight loss. Therefore, we investigated the effect of weight loss, consequent to a very low-calorie ketogenic diet, on vitamin D blood concentrations. Methods: A cohort of 31 people with obesity underwent a very low-calorie ketogenic diet for 10–12 weeks. The serum concentrations of vitamin D, parathormone, calcium and phosphorous were measured before and after weight loss; they were compared to a control group of 20 non-obese, non-diabetic, age- and gender-matched persons. Results: Patients with obesity had a higher habitual intake of vitamin D than the control group (p < 0.05). However, the vitamin D blood levels of the obese group were significantly lower than those of the control group (p < 0.005) and they increased after weight loss (p < 0.001). At baseline, vitamin D blood concentrations of the persons with obesity were significantly correlated with both fat mass–kg (r = −0.40; p < 0.05) and body mass index (r = −0.47; p < 0.01). Following very low-calorie ketogenic diet, the change in vitamin D serum concentrations was correlated only with the change in fat mass–kg (r = −0.43; p < 0.01). Conclusion: This study confirmed that patients with obesity have lower vitamin D levels that normalize after significant weight loss, supporting the hypothesis that vitamin D is stored in the adipose tissue and released following weight loss. 相似文献
22.
Louise B. Russell Sun-Young Kim Cristiana Toscano Ben Cosgriff Ruth Minamisava Ana Lucia Andrade Colin Sanderson Anushua Sinha 《Vaccine》2021,39(1):158-166
BackgroundThis paper compares cost-effectiveness results from two models of maternal immunization to prevent pertussis in infants in Brazil, one static, one dynamic, to explore when static models are adequate for public health decisions and when the extra effort required by dynamic models is worthwhile.MethodsWe defined two scenarios to explore key differences between static and dynamic models, herd immunity and time horizon. Scenario 1 evaluates the incremental cost/DALY of maternal acellular pertussis (aP) immunization as routine infant vaccination coverage ranges from low/moderate up to, and above, the threshold at which herd immunity begins to eliminate pertussis. Scenario 2 compares cost-effectiveness estimates over the models’ different time horizons. Maternal vaccine prices of $9.55/dose (base case) and $1/dose were evaluated.ResultsThe dynamic model shows that maternal immunization could be cost-saving as well as life-saving at low levels of infant vaccination coverage. When infant coverage reaches the threshold range (90–95%), it is expensive: the dynamic model estimates that maternal immunization costs $2 million/DALY at infant coverage > 95% and maternal vaccine price of $9.55/dose; at $1/dose, cost/DALY is $200,000. By contrast, the static model estimates costs/DALY only modestly higher at high than at low infant coverage. When the models’ estimates over their different time horizons are compared at infant coverage < 90–95%, their projections fall in the same range.ConclusionsStatic models may serve to explore an intervention’s cost-effectiveness against infectious disease: the direction and principal drivers of change were the same in both models. When, however, an intervention too small to have significant herd immunity effects itself, such as maternal aP immunization, takes place against a background of vaccination in the rest of the population, a dynamic model is crucial to accurate estimates of cost-effectiveness. This finding is particularly important in the context of widely varying routine infant vaccination rates globally.Clinical Trial registryClinical Trial registry name and registration number: Not applicable. 相似文献
23.
24.
Sun-Young Kim Kyung-Duk Min Sung-mok Jung Louise B. Russell Cristiana Toscano Ruth Minamisava Ana Lucia S. Andrade Colin Sanderson Anushua Sinha 《Vaccine》2021,39(1):147-157
ObjectiveThis study evaluates the cost-effectiveness of maternal acellular pertussis (aP) immunization in low- and middle-income countries using a dynamic transmission model.MethodsWe developed a dynamic transmission model to simulate the impact of infant vaccination with whole-cell pertussis (wP) vaccine with and without maternal aP immunization. The model was calibrated to Brazilian surveillance data and then used to project health outcomes and costs under alternative strategies in Brazil, and, after adjusting model parameter values to reflect their conditions, in Nigeria and Bangladesh. The primary measure of cost-effectiveness is incremental cost (2014 USD) per disability-adjusted life-year (DALY).ResultsThe dynamic model shows that maternal aP immunization would be cost-effective in Brazil, a middle-income country, under the base-case assumptions, but would be very expensive at infant vaccination coverage in and above the threshold range necessary to eliminate the disease (90–95%). At 2007 infant coverage (DTP1 90%, DTP3 61% at 1 year of age), maternal immunization would cost < $4,000 per DALY averted. At high infant coverage, such as Brazil in 1996 (DTP1 94%, DTP3 74% at 1 year), cost/DALY increases to $1.27 million. When the model’s time horizon was extended from 2030 to 2100, cost/DALY increased under both infant coverage levels, but more steeply with high coverage. The results were moderately sensitive to discount rate, maternal vaccine price, and maternal aP coverage and were robust using the 100 best-fitting parameter sets. Scenarios representing low-income countries showed that maternal aP immunization could be cost-saving in countries with low infant coverage, such as Nigeria, but very expensive in countries, such as Bangladesh, with high infant coverage.ConclusionA dynamic model, which captures the herd immunity benefits of pertussis vaccination, shows that, in low- and middle-income countries, maternal aP immunization is cost-effective when infant vaccination coverage is moderate, even cost-saving when it is low, but not cost-effective when coverage levels pass 90–95%. 相似文献
25.
Alfonso Lagi MD Marcello Cipriani MD Lamberto Fattorini MD Cristiano Paggetti PhD Alberto Macerata PhD 《Clinical autonomic research》1994,4(6):307-309
The arterial baroreflex was studied in subjects who had recently had an episode of vasodepressor syncope. This was determined using 2–3 mcg/kg intravenous boluses of phenylephrine and assessing the bradycardic response. The values were measured in ms/mmHg and expressed as the angular coefficient of the regression line between the increase in R—R interval on the electrocardiograph and the systolic arterial pressure. In subjects examined immediately after the vasodepressor syncope episode the bradycardic response was much more marked than in controls (p < 0.01) and in the subjects themselves 6 months after the episode, provided that they were symptom-free (p < 0.01). It is concluded that in vasodepressor syncope there is a phase in which the baroreflex is highly sensitive and that this is due not to a lowering of the stimulation threshold but to a gain in the efferent arc, which explains a vagotonic response. 相似文献
26.
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
27.
S. K. Shukla G. B. Manni C. Cipriani 《European journal of nuclear medicine and molecular imaging》1977,2(3):137-141
Cases of reduced uptake of pertechnetate-99m ion in the thyroid gland due to the presence, in the injected solution, of aluminium species at concentrations higher than 4 g/cm3 are reported. This inconvenience can be avoided either by injecting chromatographically pure pertechnetate-99m ion or by allowing the eluate of high aluminium content to stand for about 4 h. 相似文献
28.
Capogna G Celleno D Sebastiani M Muratori F Costantino P Cipriani G Passarelli F Varrassi G 《International Journal of Obstetric Anesthesia》1991,1(1):19-23
In 56 women undergoing elective caesarean section, general anaesthesia was induced with either propofol 1% or thiopentone 2.5% followed by 50% nitrous oxide in oxygen and isoflurane 0.75% until delivery. In the thiopentone group the arterial pressure rose following tracheal intubation and skin incision, while in the propofol group there was a significant tendency to hypotension immediately following induction of anaesthesia. There were differences in electroencephalogram (EEG) between the groups, while laryngoscopy, intubation and surgical stimulation had no effect on EEG pattern. Recovery after anaesthesia did not differ between groups. None of the patients had recall of the intraoperative period, but 53% of patients induced with propofol showed signs of light anaesthesia between induction and delivery. Neonates in the propofol group had lower Apgar scores 1 min after birth than those in the thiopentone group, but these differences were no longer significant at 5 min. No differences were noted in neurobehavioural status at 1, 4 and 24 h. 相似文献
29.
Flavia Bortolotti MD Massimo Resti MD Raffaella Giacchino MD Chiara Azzari MD Nadia Gussetti MD Carlo Crivellaro MD Cristiana Barbera MD Francesco Mannelli MD Lucia Zancan MD Adalberto Bertolini MD 《The Journal of pediatrics》1997,130(6):990-993
Objective: To evaluate the clinical, biochemical, and virologic features associated with hepatitis C virus (HCV) infection acquired early in life from mothers with antibodies to HCV (anti-HCV).Study design: Multicenter prospective-retrospective study in Italian children.Patients: Two groups of children were investigated. Group 1 included 14 infants, born to mothers with anti-HCV but without human immunodeficiency virus infection, who became seropositive for HCV RNA during the first year of life and were thus considered infected. Group 2 included 16 children with chronic hepatitis C, aged 1
½ to 14 years, whose mothers were the unique potential source of infection. Both groups were followed for 12 to 48 months.Methods: Alanine transaminase (ALT), anti-HCV, and HCV RNA were investigated by the polymerase chain reaction on entry to the study and during follow-up.Results: All children in group 1 had anti-HCV throughout follow-up, and all had ALT abnormalities, ranging from 1.5 to 10.5 times the normal value during the first 12 months. During further follow-up, 5 of 10 children had HCV RNA with abnormal ALT values, 3 had a return to normal of the ALT values but continued to have viremia, and 2 eventually had normal ALT values and clearance of HCV RNA. Of the 16 children in group 2, all were free of symptoms and 62% had only slight ALT elevations; 7 who underwent liver biopsy had histologic features of minimal or moderate hepatitis.Conclusions: HCV infection acquired early in life from mothers with anti-HCV is usually associated with biochemical features of liver damage during the first 12 months of life. Progression to chronicity seems to occur in the majority of cases, although HCV-associated liver disease is likely to be mild throughout infancy and childhood. (J Pediatr 1997;130:990-3) 相似文献
30.
Vascular endothelial growth factor and basic fibroblast growth factor in polycystic ovary syndrome during controlled ovarian hyperstimulation. 总被引:4,自引:0,他引:4
Paolo Giovanni Artini Massimiliano Monti Cristiana Matteucci Valeria Valentino Francesca Cristello Andrea Riccardo Genazzani 《Gynecological endocrinology》2006,22(8):465-470
BACKGROUND: Polycystic ovary syndrome (PCOS) is a common endocrine disorder that causes anovulation and consequent subfertility. It is well established that increased ovarian mass, supported by new blood vessel proliferation in stroma and theca, is a key feature of PCOS. Recent studies suggest a role for angiogenetic factors in this phenomenon. AIM: To evaluate of levels of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in serum and follicular fluid of PCOS patients during a controlled ovarian hyperstimulation. METHODS: In 52 patients undergoing in vitro fertilization treatments, 26 PCOS patients and 26 controls, serum VEGF and bFGF levels were assessed before starting administration of follicle-stimulating hormone (FSH) (day 0), on the day of administration of human chorionic gonadotropin (hCG) and on the day of oocyte retrieval. Follicular fluid levels of the two growth factors were detected on the day of oocyte retrieval. RESULTS: PCOS patients showed higher serum VEGF levels than controls before starting FSH administration, on the day of hCG administration and on the day of oocyte retrieval. Serum VEGF levels showed a rise after hCG administration only in the PCOS patients. In addition, serum bFGF levels were higher in PCOS patients than in controls on the day of hCG administration and the day of oocyte retrieval. Furthermore, on the day of hCG administration, serum bFGF levels were directly correlated to the amount of FSH previously administered (p < 0.0001). In follicular fluid, higher VEGF and bFGF levels were found in PCOS patients than in controls. Furthermore, follicular-fluid bFGF concentrations were inversely correlated with the percentage of mature oocytes collected (p < 0.05). CONCLUSIONS: The present study revealed elevated levels of VEGF and bFGF in serum and follicular fluid in PCOS patients compared with controls. bFGF seems to be an FSH-dependent growth factor and its levels in follicular fluid are inversely correlated with the percentage of mature oocytes collected. 相似文献