全文获取类型
收费全文 | 12646篇 |
免费 | 847篇 |
国内免费 | 128篇 |
专业分类
耳鼻咽喉 | 120篇 |
儿科学 | 322篇 |
妇产科学 | 432篇 |
基础医学 | 1638篇 |
口腔科学 | 430篇 |
临床医学 | 1181篇 |
内科学 | 2730篇 |
皮肤病学 | 230篇 |
神经病学 | 1008篇 |
特种医学 | 605篇 |
外国民族医学 | 3篇 |
外科学 | 1941篇 |
综合类 | 268篇 |
一般理论 | 4篇 |
预防医学 | 652篇 |
眼科学 | 130篇 |
药学 | 648篇 |
1篇 | |
中国医学 | 48篇 |
肿瘤学 | 1230篇 |
出版年
2023年 | 76篇 |
2022年 | 128篇 |
2021年 | 357篇 |
2020年 | 190篇 |
2019年 | 264篇 |
2018年 | 343篇 |
2017年 | 232篇 |
2016年 | 280篇 |
2015年 | 323篇 |
2014年 | 402篇 |
2013年 | 525篇 |
2012年 | 848篇 |
2011年 | 827篇 |
2010年 | 496篇 |
2009年 | 424篇 |
2008年 | 684篇 |
2007年 | 751篇 |
2006年 | 628篇 |
2005年 | 651篇 |
2004年 | 615篇 |
2003年 | 523篇 |
2002年 | 532篇 |
2001年 | 360篇 |
2000年 | 357篇 |
1999年 | 364篇 |
1998年 | 158篇 |
1997年 | 161篇 |
1996年 | 128篇 |
1995年 | 101篇 |
1994年 | 123篇 |
1993年 | 100篇 |
1992年 | 179篇 |
1991年 | 173篇 |
1990年 | 133篇 |
1989年 | 165篇 |
1988年 | 121篇 |
1987年 | 141篇 |
1986年 | 98篇 |
1985年 | 84篇 |
1984年 | 74篇 |
1983年 | 44篇 |
1982年 | 32篇 |
1981年 | 38篇 |
1980年 | 34篇 |
1979年 | 54篇 |
1978年 | 27篇 |
1976年 | 43篇 |
1975年 | 26篇 |
1974年 | 29篇 |
1972年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Diouf M Cisse D Lo CM Ly M Faye D Ndiaye O 《Revue d'épidémiologie et de santé publique》2012,60(2):103-108
BackgroundIn developing countries, maternal and neonatal mortality is high. Among the causes of death during the neonatal period, low birth weight is crucial. A dose of fluoride beyond 2 mg/L causes enamel damage, possibly affecting the fetus. The aim of this study was to search for an association between dental fluorosis in the mother and low birthweight of the newborn.MethodologyThis was a case–control study performed in an endemic area in Senegal (Diourbel). It included 108 mothers who gave birth to newborns weighing less than 2500 g (cases) and 216 mothers with newborns weighing greater or equal to 2500 g (controls). Data on socio-demographic, lifestyle, history and pregnancy variables were collected. Those related to water consumption during pregnancy and dental fluorosis (Dean's index) were measured. The data were analyzed by R software. Logistic regression was used to identify associations and the statistical significance level was set to 0.05.ResultsThe proportions of mothers consuming well water were 62% among cases versus 43.5% among controls. The score 4 of Dean's Index was reported for 25.9% of cases versus 6.9% of controls. The water consumed and the modal score of Dean's Index were significantly associated with the occurrence of low birthweight adjusted for gender, consanguinity, anemia and hypertension.ConclusionLow birthweight was associated with pregnant women living in endemic areas. Defluoridation programs and access for pregnant women and children to high quality water are necessary in areas of endemic fluorosis. 相似文献
992.
Lim U Ernst T Wilkens LR Albright CL Lum-Jones A Seifried A Buchthal SD Novotny R Kolonel LN Chang L Cheng I Le Marchand L 《Journal of the Academy of Nutrition and Dietetics》2012,112(7):1048-1055
Genome-wide association studies have identified common genetic variants that can contribute specifically to the risk of abdominal adiposity, as measured by waist circumference or waist-to-hip ratio. However, it is unknown whether these genetic risk factors affect relative body fat distribution in the abdominal visceral and subcutaneous compartments. The association between imaging-based abdominal fat mass and waist-size risk variants in the FTO, LEPR, LYPLAL1, MSRA, NRXN3, and TFAP2B genes was investigated. A cross-sectional sample of 60 women was selected among study participants of The Multiethnic Cohort, who were aged 60 to 65 years, of European or Japanese descent, and with a body mass index (calculated as kg/m(2)) between 18.5 and 40. Dual-energy x-ray absorptiometry and abdominal magnetic resonance imaging scans were used to measure adiposity. After adjustments for age, ethnicity, and total fat mass, the FTO variants showed an association with less abdominal subcutaneous fat and a higher visceral-to-subcutaneous abdominal fat ratio, with the variant rs9941349 showing significant associations most consistently (P=0.003 and 0.03, respectively). Similarly, the LEPR rs1137101 variant was associated with less subcutaneous fat (P=0.01) and a greater visceral-to-subcutaneous fat ratio (P=0.03) and percent liver fat (P=0.007). MSRA rs545854 variant carriers had a lower percent of leg fat. Our findings provide initial evidence that some of the genetic risk factors identified for larger waist size might also contribute to disproportionately greater intra-abdominal and liver fat distribution in postmenopausal women. If replicated, these genetic variants can be incorporated with other biomarkers to predict high-risk body fat distribution. 相似文献
993.
Novel action of lignans isolated from Hernandia nymphaeifolia on Ca2+ signaling in human neutrophils 总被引:2,自引:0,他引:2
Chao YY Su W Jan CR Ko YC Chen JJ Cheng JS Liu CP Lo YK Chou KJ Lee KC Chen WC Chen IS 《Archives of toxicology》2002,75(11-12):695-702
The effects of five lignans (epi-aschantin, epi-magnolin, epi-yangambin, deoxypodophyllotoxin, yatein) isolated from Hernandia nymphaeifolia (Presl.) Kubitzki (Hernandiaceae) on intracellular Ca2+ levels ([Ca2+]i) in human neutrophils were investigated by using fura-2 as a fluorescent probe. In both Ca2+-containing and Ca2+-free media, the lignans (50-100 microM) did not alter basal [Ca2+]i but inhibited the [Ca2+]i increase induced by platelet activating factor (PAF, 10 microM), leukotriene B4 (LTB4, 0.2 microM), and thapsigargin (1 microM) to different extents. In Ca2+-free medium, after depleting stores of Ca2+ with PAF, LTB4 or thapsigargin, addition of 3 mM Ca2+ induced Ca2+ influx. Each of the lignans (50-100 microM) caused 39-89% inhibition of PAF-induced Ca2+ influx; whereas only epi-aschantin was able to inhibit LTB4- and thapsigargin-induced Ca2+ influx by 54-79%. Together, the results suggest that in human neutrophils, these lignans did not alter basal [Ca2+]i but inhibited Ca2+ movement induced by Ca2+ mobilizing agents. 相似文献
994.
Allela L Boury O Pouillot R Délicat A Yaba P Kumulungui B Rouquet P Gonzalez JP Leroy EM 《Emerging infectious diseases》2005,11(3):385-390
During the 2001-2002 outbreak in Gabon, we observed that several dogs were highly exposed to Ebola virus by eating infected dead animals. To examine whether these animals became infected with Ebola virus, we sampled 439 dogs and screened them by Ebola virus-specific immunoglobulin (Ig) G assay, antigen detection, and viral polymerase chain reaction amplification. Seven (8.9%) of 79 samples from the 2 main towns, 15 (15.2%) of 99 samples from Mekambo, and 40 (25.2%) of 159 samples from villages in the Ebola virus-epidemic area had detectable Ebola virus-IgG, compared to only 2 (2%) of 102 samples from France. Among dogs from villages with both infected animal carcasses and human cases, seroprevalence was 31.8%. A significant positive direct association existed between seroprevalence and the distances to the Ebola virus-epidemic area. This study suggests that dogs can be infected by Ebola virus and that the putative infection is asymptomatic. 相似文献
995.
Lo HC Tsao LY Hsu WY Chi CY Tsai FA 《JPEN. Journal of parenteral and enteral nutrition》2005,29(2):87-92
BACKGROUND: Serum concentrations of conventional nutrition-related proteins, such as albumin, prealbumin, transferrin, and retinol-binding protein, are usually inconsistent with changes in anthropometric measurements in the postnatal period. The aim of this study was to evaluate how reliable growth hormone (GH), insulin-like growth factors (IGFs), IGF-binding proteins (IGFBPs), and leptin, the proteins known to be involved in the regulation of growth, are in reflecting postnatal growth and nutritional status in preterm neonates. METHODS: Blood samples and anthropometric measurements were collected from 55 preterm neonates (chronological age 30.4 +/- 2.8 weeks) for 4 continuous weeks (weeks 0 to 3). RESULTS: After adjusting for chronological age, body weights and serum IGF-II concentrations were significantly greater and serum transferrin concentrations were significantly lower in weeks 2 and 3 than in week 0 (repeated-measures analysis of variance (ANOVA) and Bonferroni test, p < .05). Forward stepwise multivariate regression analysis showed that change in total IGF-I (week 0 to week 3) was a positive predictor, and changes in insulin and prealbumin were negative predictors of postnatal weight gain. In addition, daily fat intake was a positive predictor of postnatal length increases, and changes in prealbumin, insulin, and GH were negative predictors of postnatal changes in the ponderal index (weight x length(-3)). Changes in GH and IGFBP-2 were negative predictors of changes in head circumference and triceps skinfold thickness, respectively. CONCLUSIONS: Serial measurements of serum IGF-I and IGF-II may be useful adjuncts to anthropometric measurements for monitoring postnatal growth and nutritional status in preterm neonates. 相似文献
996.
INTRODUCTION: This paper examines smoking prevalence, sociodemographic factors and the medical practice of French general practitioners. METHOD: Data from the 1998 cross-sectional national survey of 2,073 GPs. The questionnaire was administered by telephone. A response rate of 67% was attained. Instrumentation included questions about medical practice, sociodemographic characteristics, and health behaviour. Bivariate and multiple logistic regression (MLR) analyses were conducted. RESULTS: Almost one-third (32.1%) of physicians were current smokers. A significantly higher proportion of male (33.9%) were smokers compared to women (25.4%, p<0.001) and men were more likely to be former smokers (49.1% versus 31.7%). Two-thirds of physicians reported recommending nicotine replacement therapy to their patients. MLR shown that former smokers were more likely (OR = 1.51, 95% CI, 1.24-1.83) to indicate that their help in getting patients to quit was not effective compared to smokers. Also, physicians who were 'dissatisfied' with the profession were more likely (OR = 0.75, 95% CI, 0.60-0.92) to report their help as not effective than those who were 'satisfied'. CONCLUSION: These data support the need for greater professional participation in reducing smoking among general practitioners in France and greater education concerning the vital role of physicians in promoting cessation among the general population. KEY POINTS: This study examines smoking habits among French GP's, intervention practices, and opinions about their ability to help patients quit smoking. This study found a smoking prevalence rate of 32.1%, 33.9% of male physicians were smokers and 25.4% of women. This study found a smoking prevalence rate of 32.1%, 33.9% of male physicians were smokers and 25.4% of women. 相似文献
997.
Incidence and duration of hospitalizations among persons with AIDS: an event history approach 下载免费PDF全文
OBJECTIVE: To analyze hospitalization patterns of persons with AIDS (PWAs) in a multi-state/multi-episode continuous time duration framework. DATA SOURCES: PWAs on Medicaid identified through a match between the state's AIDS Registry and Medicaid eligibility files; hospital admission and discharge dates identified through Medicaid claims. STUDY DESIGN: Using a Weibull event history framework, we model the hazard of transition between hospitalized and community spells, incorporating the competing risk of death in each of these states. Simulations are used to translate these parameters into readily interpretable estimates of length of stay, the probability that a hospitalization will end in death, and the probability that a nonhospitalized person will be hospitalized within 90 days. PRINCIPAL FINDINGS: In multivariate analyses, participation in a Medicaid waiver program offering case management and home care was associated with hospital stays 1.3 days shorter than for nonparticipants. African American race and Hispanic ethnicity were associated with hospital stays 1.2 days and 1.0 day longer than for non-Hispanic whites; African Americans also experienced more frequent hospital admissions. Residents of the high-HIV-prevalence area of the state had more frequent admissions and stays two days longer than those residing elsewhere in the state. Older PWAs experienced less frequent hospital admissions but longer stays, with hospitalizations of 55-year-olds lasting 8.25 days longer than those of 25-year-olds. CONCLUSIONS: Much socioeconomic and geographic variability exists both in the incidence and in the duration of hospitalization among persons with AIDS in New Jersey. Event history analysis provides a useful statistical framework for analysis of these variations, deals appropriately with data in which duration of observation varies from individual to individual, and permits the competing risk of death to be incorporated into the model. Transition models of this type have broad applicability in modeling the risk and duration of hospitalization in chronic illnesses. 相似文献
998.
子宫颈癌组织细胞凋亡、增殖细胞核抗原及P53蛋白表达的实验研究 总被引:1,自引:0,他引:1
目的:探讨细胞凋亡及增殖细胞核抗原(PCNA)与子宫颈癌的关系。方法:采用原位末端标记法(TUNEL)检测细胞凋亡,采用免疫组化技术检测PCNA和P53蛋白。结果:32例子宫颈鳞癌组织中,细胞凋亡、P53蛋白和PCNA阳性率分别为62.50%,53.13%和65.63%。表达P53蛋白的细胞与表达PCNA细胞分布区域基本一致,与细胞凋亡无明显相关性。正常子宫颈组织只有上皮组织内有少数凋亡细胞和表达PCNA的细胞,显微镜下每视野阳性细胞数均不超过10%。结论:P53蛋白可能通过促进细胞增殖,抑制细胞凋亡而参与子宫颈癌发生与发展。 相似文献
999.
Kuo HW Huang YS Lo JC Cheng TJ Wu MJ 《International archives of occupational and environmental health》2000,73(4):275-280
The objective of this study was to evaluate the exposure of synthetic leather workers to dimethylformamide (DMF), epichlorohydrin
(ECH) and toluene, in a manufacturing plant. The correlation between biological and environmental monitoring for DMF was also
investigated. Environmental monitoring of the three solvents included personal and area sampling based on time of day (morning
and afternoon). Urine samples were taken at the end of the shift and urinary N-methylformamide (NMF) was then used to biologically monitor DMF levels. Results for solvent concentrations based on air sampling
were considerably higher in area than in personal sampling. Of 41 area samples, 15 (36.6%) and five (12.2%) exceeded permissible
exposure levels for DMF and ECH, respectively, compared with 22 (28.6%) and three (3.9%) based on 77 personal samples. Overall,
urinary NMF concentrations were lower than the Biological Exposure Index (BEI) suggested by the American Conference of Governmental
Industrial Hygienists (ACGIH). A significant correlation (r=0.32; P < 0.05) was found between environmental and biological monitoring. Even though urinary NMF concentration was within permissible
levels for Taiwan, the authors recommend that immediate measures be taken to decrease DMF and ECH concentrations in synthetic
leather manufacturing plants.
Received: 14 June 1999 / Accepted: 20 November 1999 相似文献
1000.
Eating disorder symptoms in a cohort of 11 to 16-year-old black and white girls: the NHLBI growth and health study 总被引:4,自引:0,他引:4
Striegel-Moore RH Schreiber GB Lo A Crawford P Obarzanek E Rodin J 《The International journal of eating disorders》2000,27(1):49-66
OBJECTIVE: This study sought to provide reference data for the Eating Disorder Inventory (EDI) with use of young adolescent black and white girls. Moreover, the study examined the relationship between race, age, socioeconomic status, and adiposity and each of the eight EDI scales. METHOD: To achieve these aims, data were used that had been collected in Years 3, 5, and 7 as part of the National Heart, Lung, and Blood Institute Growth and Health Study, a longitudinal cohort study of risk factors for obesity in black and white girls. For the present report, data were available from 2,228 girls in Year 3, 2,056 girls in Year 5, and 1,902 girls in Year 7. RESULTS: EDI scores were found to vary by race, age, socioeonomic status, and body weight of respondents. Black girls scored different from white girls on all EDI subscales. Scores on all but two subscales (Body Dissatisfaction, Drive for Thinness) decreased significantly with increasing age. Significant inverse associations were found between maximum parental education and all EDI subscales except Body Dissatisfaction and Perfectionism. Elevated body weight was associated significantly with Body Dissatisfaction, Drive for Thinness, Bulimia, Interoceptive Awareness, and Ineffectiveness. DISCUSSION: Our results illustrate the importance of taking into consideration the potentially confounding role of demographic characteristics and body weight when comparing different race or ethnic groups on the EDI. 相似文献