全文获取类型
收费全文 | 3309篇 |
免费 | 190篇 |
国内免费 | 25篇 |
专业分类
耳鼻咽喉 | 71篇 |
儿科学 | 235篇 |
妇产科学 | 156篇 |
基础医学 | 324篇 |
口腔科学 | 105篇 |
临床医学 | 338篇 |
内科学 | 667篇 |
皮肤病学 | 128篇 |
神经病学 | 171篇 |
特种医学 | 142篇 |
外科学 | 371篇 |
综合类 | 77篇 |
预防医学 | 243篇 |
眼科学 | 72篇 |
药学 | 257篇 |
中国医学 | 19篇 |
肿瘤学 | 148篇 |
出版年
2023年 | 50篇 |
2022年 | 78篇 |
2021年 | 145篇 |
2020年 | 95篇 |
2019年 | 148篇 |
2018年 | 138篇 |
2017年 | 105篇 |
2016年 | 162篇 |
2015年 | 127篇 |
2014年 | 162篇 |
2013年 | 220篇 |
2012年 | 287篇 |
2011年 | 267篇 |
2010年 | 143篇 |
2009年 | 138篇 |
2008年 | 169篇 |
2007年 | 209篇 |
2006年 | 184篇 |
2005年 | 175篇 |
2004年 | 152篇 |
2003年 | 81篇 |
2002年 | 88篇 |
2001年 | 15篇 |
2000年 | 16篇 |
1999年 | 12篇 |
1998年 | 20篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 11篇 |
1994年 | 16篇 |
1993年 | 13篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1980年 | 4篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 2篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1875年 | 1篇 |
排序方式: 共有3524条查询结果,搜索用时 156 毫秒
151.
Faisel H Majoko F Shebl F Lindsay P 《European journal of obstetrics, gynecology, and reproductive biology》2008,139(2):164-168
Objective
To assess trends in twinning over four decades using a population-based registry.Design
Ecological study to conduct trend analysis of twin pregnancies in a geographically defined area over 40 years.Setting
All pregnancies in the Cardiff and Vale of Glamorgan area of South Wales from 1965 to 2004, as recorded in the Cardiff Birth Survey (CBS) database.Methods
Trends of the incidence of all twin pregnancies (≥18 weeks of gestation) were calculated in 5-year increments, beginning with 1965–1969 and ending in 2000–2004. Natural twinning rates could only be calculated for the terminal five time periods (i.e., 1980–1984, 1985–1989, 1990–1994, 1995–1999, and 2000–2004), when information regarding non-spontaneous (iatrogenic) twinning was first collected in the database. All results were adjusted for maternal age.Results
The total twinning rate was 13.1 per 1000 pregnancies in the 1st time period (1965–1969). Subsequently, there was a gradual reduction in twinning, reaching a nadir of 10.3 per 1000 for the time period 1980–1985 (Z = 3.15, P value < 0.001). This was followed by a gradual increase in twinning, reaching a maximum of 15.7 per 1000 for both 1995–1999 and 2000–2004 (Z = −5.18, P value < 0.0001). After exclusion of the cases of iatrogenic pregnancies, the natural twinning rate showed a continuous and gradual increase from 10 per 1000 spontaneous pregnancies in 1980–1984 to 13.3 per 1000 in 2000–2004 (Z = −5.08, P value < 0.0001).Conclusion
The data showed a gradual, continuous increase in natural twinning rates over the last two decades. Such an increase cannot be attributed to the rise in maternal age alone. 相似文献152.
Cebesoy FB 《Fertility and sterility》2008,89(4):1025-1025; author reply 1026
153.
Abdel Bar FM Zaghloul AM Bachawal SV Sylvester PW Ahmad KF El Sayed KA 《Journal of natural products》2008,71(10):1787-1790
Three new 28-norlupane triterpenes, 28-norlup-20(29)-en-3beta-hydroxy-17beta-hydroperoxide (1), 28-norlup-20(29)-en-3beta-hydroxy-17alpha-hydroperoxide (2), and 20 S-17beta,29-epoxy-28-norlupan-3beta-ol (3), were isolated from the leaves of Melaleuca ericifolia along with eight known pentacyclic triterpenes. The structures of the new compounds were elucidated by spectroscopic methods including 1D and 2D NMR spectroscopy and mass spectrometry. The isolated triterpenes were evaluated for antiproliferative activity against the malignant +SA mammary epithelial cell line. 相似文献
154.
Serum ghrelin, leptin and resistin levels in adolescent girls with polycystic ovary syndrome 总被引:1,自引:0,他引:1
Bideci A Camurdan MO Yeşilkaya E Demirel F Cinaz P 《The journal of obstetrics and gynaecology research》2008,34(4):578-584
Aim: The aim of the present study was to investigate the levels of leptin, resistin and ghrelin in polycystic ovary syndrome (PCOS), and to assess their possible correlations with the hormonal and metabolic features of PCOS.
Methods: Sixteen obese (ObPCOS) and 12 lean (LeanPCOS) subjects with PCOS and 19 obese control subjects were enrolled in the study.
Results: Ghrelin, leptin and resistin concentrations were similar between groups when body mass index (BMI) was used as a covariate ( P > 0.05). Mean androgen, SHBG, luteinizing hormone (LH) levels and luteinizing hormone/follicle-stimulating hormone (LH/FSH) ratio tended to be similar between polycystic ovary syndrome (PCOS) groups. However, when compared with the control group, SHBG was lower and androgen, LH levels and LH/FSH ratio were higher in the PCOS groups. Free testosterone levels significantly correlated with resistin (r = −0.38), SHBG correlated significantly with body mass index (BMI) (r = −0.45) and resistin (r = −0.67), LH/FSH ratio was significantly correlated with ghrelin (r = −0.52) and estradiol (E2) levels (r = 0.51).
Conclusion: ObPCOS and LeanPCOS groups having higher LH/FSH ratios and lower SHBG levels suggest that there could be factors other than adiposity responsible for the clinical features of PCOS patients. In the light of our results, those factors can be suggested as ghrelin and E2 for the elevated LH/FSH ratio and resistin for the lowered SHBG. 相似文献
Methods: Sixteen obese (ObPCOS) and 12 lean (LeanPCOS) subjects with PCOS and 19 obese control subjects were enrolled in the study.
Results: Ghrelin, leptin and resistin concentrations were similar between groups when body mass index (BMI) was used as a covariate ( P > 0.05). Mean androgen, SHBG, luteinizing hormone (LH) levels and luteinizing hormone/follicle-stimulating hormone (LH/FSH) ratio tended to be similar between polycystic ovary syndrome (PCOS) groups. However, when compared with the control group, SHBG was lower and androgen, LH levels and LH/FSH ratio were higher in the PCOS groups. Free testosterone levels significantly correlated with resistin (r = −0.38), SHBG correlated significantly with body mass index (BMI) (r = −0.45) and resistin (r = −0.67), LH/FSH ratio was significantly correlated with ghrelin (r = −0.52) and estradiol (E2) levels (r = 0.51).
Conclusion: ObPCOS and LeanPCOS groups having higher LH/FSH ratios and lower SHBG levels suggest that there could be factors other than adiposity responsible for the clinical features of PCOS patients. In the light of our results, those factors can be suggested as ghrelin and E2 for the elevated LH/FSH ratio and resistin for the lowered SHBG. 相似文献
155.
Madelon N.M. Van Der Aa Milou D. Bekker Theo H. Van Der Kwast Marie‐Louise Essink‐Bot Ewout W. Steyerberg Ellen C. Zwarthoff Fatma E.F. Sen Henk W. Elzevier 《BJU international》2009,104(1):35-40
OBJECTIVE
To describe the prevalence of sexual dysfunction and evaluate risk factors in patients just diagnosed with non‐muscle‐invasive bladder cancer (NMI UC), who have the prospect of an intensive surveillance scheme by cysto‐urethroscopy to detect tumour recurrences.PATIENTS AND METHODS
We conducted a cross‐sectional survey on 150 patients just diagnosed with primary or recurrent NMI UC. Patients were participating in a randomized clinical multicentre trial (CEFuB), comparing two surveillance schemes. Patients were asked to complete questionnaires at study entry 3 months before the start of the study‐surveillance scheme (demographic characteristics, a validated visual analogue scale, and validated subset of questions on sexual function and performance derived from QLQ‐BLS‐24). The results were compared with those from an age‐and gender‐matched healthy population.RESULTS
The response rate was 95% (142/150); 61% (87/142) of the respondents were sexually active in the previous 4 weeks after diagnosis, 66% (70/105) of men and 46% (17/37) of women. Although libido was not negatively affected, 54% (47/87) of the patients had a sexual dysfunction, and 23% (17/73) were afraid to inflict harm on their partner by sexual contact. Sexually active patients perceived a higher state of general health (P = 0.03).CONCLUSIONS
The prevalence of sexual dysfunction in patients with NMI UC is very high (54%) compared with an age‐ and gender‐matched healthy population (20–45%). No predictors for sexual dysfunction were found. These patients and partners would benefit from proper sexual information in the outpatient clinic. 相似文献156.
Contribution of diffusion‐weighted imaging to dynamic contrast‐enhanced MRI in the characterization of papillary breast lesions
下载免费PDF全文
![点击此处可从《The breast journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Seyma Yildiz MD Huseyin Toprak MD Yeliz Emine Ersoy MD Fatma Ümit Malya MD Ayşe Ahsen Bakan MD Ayşe Aralaşmak MD Zuhal Gucin MD 《The breast journal》2018,24(2):176-179
Papillary lesions have a broad spectrum of appearances on magnetic resonance imaging (MRI ). The purpose of this study was to evaluate whether apparent diffusion coefficient (ADC ) values of papillary lesions can be used to characterize lesion as benign or malignant. This retrospective study included 29 papillary lesions. Diagnostic values of dynamic contrast‐enhanced MRI (DCE‐MRI), DWI ‐ADC , and DCE ‐MRI plus DWI ‐ADC were separately calculated. The malignant papillary lesions (0.744×10?3 mm2/s) exhibited significantly lower mean ADC values than the benign lesions (1.339×10?3 mm2/s). Addition of DWI to standard DCE ‐MRI provided 100% sensitivity. We hypothesized that this combination may prevent unnecessary excisional biopsies. 相似文献
157.
158.
Ibrahim Yildiz Fatma Sen Leyla Kilic Serkan Keskin Derya Duranyildiz Elif Bilgin Rian Disci Meltem Ekenel Emin Darendeliler Sevil Bavbek Mert Basaran 《Clinical genitourinary cancer》2013,11(3):290-296
Introduction/BackgroundEffective cancer biomarkers for early detection, prognosis, or therapy response prediction are urgently need in metastatic RCC. M30 and M65 are released during apoptotic cell death and precisely reflect epithelial tumor cell death. The aim of this study was to determine the prognostic value of plasma M30 and M65 levels in predicting survival rates for patients with metastatic RCC.Patients and MethodsThirty-nine patients with metastatic RCC and 39 healthy control subjects were included in this study. Serum M30 and M65 levels were measured by ELISA.ResultsThe median ages of the patients and control subjects were 60 and 58 years, respectively. No difference was detected in the median serum M30 level between the patients and control subjects (53.7 vs. 49.1 U/L; P = .31). The median serum M65 level was significantly higher in patients than in control subjects (334.0 vs. 179.1 U/L; P < .001). Receiver operating characteristic analysis revealed that the best cutoff value for serum M65 level for predicting progression-free survival (PFS) was 313.6 U/L. The median PFS of patients whose M65 levels were ≤ 313.6 U/L was better than that of patients whose M65 levels were > 313.6 U/L (P = .03).ConclusionTo the best of our knowledge, this is the first study to evaluate serum M30 and M65 levels in patients with RCC. Serum M65 levels were significantly elevated in patients with metastatic RCC compared with healthy individuals. In addition, the serum M65 level could be predictive of PFS in patients with RCC. 相似文献
159.
GK Resaland A Mamen SA Anderssen LB Andersen 《Acta paediatrica (Oslo, Norway : 1992)》2009,98(4):687-692
Aim: To describe cardiorespiratory fitness and body mass index (BMI) values in a representative population of 9-year-old Norwegian children in two rural communities and compare present values with previous findings.
Methods: Two hundred and fifty-nine 9-year-old children were invited, and 256 participated in this study. Maximal oxygen uptake was directly measured during a continuous progressive treadmill protocol. Body mass and height were also measured.
Results: The mean ± SD relative maximal oxygen uptake was 52.8 ± 6.5 for boys and 46.9 ± 7.2 mL/kg/min for girls. Eight percent of the boys and 16.8% of the girls were classified as overweight, and 1.6% of the boys and 6.9% of the girls as obese. Mean age, body mass, height and Ponderal index were not significantly different between sexes. Girls had a higher BMI than boys (p = 0.05).
Conclusion: Compared to earlier Norwegian studies, children's BMI values seem to have increased substantially. This increase is most pronounced in girls. When assessing these differences using the PI, this increase is less marked. Comparing maximal oxygen uptake data with that in earlier Nordic studies, there is no evidence that fitness has declined among 9-year olds. However, the limitations of the few earlier studies make reliable comparisons difficult. 相似文献
Methods: Two hundred and fifty-nine 9-year-old children were invited, and 256 participated in this study. Maximal oxygen uptake was directly measured during a continuous progressive treadmill protocol. Body mass and height were also measured.
Results: The mean ± SD relative maximal oxygen uptake was 52.8 ± 6.5 for boys and 46.9 ± 7.2 mL/kg/min for girls. Eight percent of the boys and 16.8% of the girls were classified as overweight, and 1.6% of the boys and 6.9% of the girls as obese. Mean age, body mass, height and Ponderal index were not significantly different between sexes. Girls had a higher BMI than boys (p = 0.05).
Conclusion: Compared to earlier Norwegian studies, children's BMI values seem to have increased substantially. This increase is most pronounced in girls. When assessing these differences using the PI, this increase is less marked. Comparing maximal oxygen uptake data with that in earlier Nordic studies, there is no evidence that fitness has declined among 9-year olds. However, the limitations of the few earlier studies make reliable comparisons difficult. 相似文献
160.