全文获取类型
收费全文 | 10544篇 |
免费 | 812篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 95篇 |
儿科学 | 402篇 |
妇产科学 | 286篇 |
基础医学 | 1410篇 |
口腔科学 | 143篇 |
临床医学 | 1309篇 |
内科学 | 1931篇 |
皮肤病学 | 139篇 |
神经病学 | 1078篇 |
特种医学 | 293篇 |
外科学 | 1111篇 |
综合类 | 110篇 |
一般理论 | 9篇 |
预防医学 | 1360篇 |
眼科学 | 210篇 |
药学 | 701篇 |
中国医学 | 5篇 |
肿瘤学 | 780篇 |
出版年
2024年 | 19篇 |
2023年 | 121篇 |
2022年 | 155篇 |
2021年 | 356篇 |
2020年 | 209篇 |
2019年 | 351篇 |
2018年 | 398篇 |
2017年 | 255篇 |
2016年 | 279篇 |
2015年 | 322篇 |
2014年 | 426篇 |
2013年 | 573篇 |
2012年 | 864篇 |
2011年 | 800篇 |
2010年 | 464篇 |
2009年 | 390篇 |
2008年 | 643篇 |
2007年 | 674篇 |
2006年 | 570篇 |
2005年 | 566篇 |
2004年 | 480篇 |
2003年 | 395篇 |
2002年 | 351篇 |
2001年 | 137篇 |
2000年 | 126篇 |
1999年 | 112篇 |
1998年 | 102篇 |
1997年 | 70篇 |
1996年 | 51篇 |
1995年 | 64篇 |
1994年 | 36篇 |
1993年 | 56篇 |
1992年 | 80篇 |
1991年 | 74篇 |
1990年 | 68篇 |
1989年 | 62篇 |
1988年 | 57篇 |
1987年 | 52篇 |
1986年 | 51篇 |
1985年 | 55篇 |
1984年 | 41篇 |
1983年 | 24篇 |
1981年 | 19篇 |
1979年 | 27篇 |
1978年 | 30篇 |
1976年 | 24篇 |
1973年 | 25篇 |
1970年 | 22篇 |
1969年 | 29篇 |
1968年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
151.
Vanessa?DouetEmail author Linda?Chang Kristin?Lee Thomas?Ernst For the Pediatric Imaging Neurocognition Genetics Consortium 《Brain imaging and behavior》2015,9(1):128-140
Genetic variations in ERBB4 were associated with increased susceptibility for schizophrenia (SCZ) and bipolar disorders (BPD). Structural imaging studies showed cortical abnormalities in adolescents and adults with SCZ or BPD. However, less is known about subclinical cortical changes or the influence of ERBB4 on cortical development. 971 healthy children (ages 3–20 years old; 462 girls and 509 boys) were genotyped for the ERBB4-rs7598440 variants, had structural MRI, and cognitive evaluation (NIH Toolbox ®). We investigated the effects of ERBB4 variants and family history of SCZ and/or BPD (FH) on cortical measures and cognitive performances across ages 3–20 years using a general additive model. Variations in ERBB4 and FH impact differentially the age-related cortical changes in regions often affected by SCZ and BPD. The ERBB4-TT-risk genotype children with no FH had subtle cortical changes across the age span, primarily located in the left temporal lobe and superior parietal cortex. In contrast, the TT-risk genotype children with FH had more pronounced age-related changes, mainly in the frontal lobes compared to the non-risk genotype children. Interactive effects of age, FH and ERBB4 variations were also found on episodic memory and working memory, which are often impaired in SCZ and BPD. Healthy children carrying the risk-genotype in ERBB4 and/or with FH had cortical measures resembling those reported in SCZ or BPD. These subclinical cortical variations may provide early indicators for increased risk of psychiatric disorders and improve our understanding of the effect of the NRG1–ERBB4 pathway on brain development. 相似文献
152.
Objective The beneficial effects of metformin in patients with type 2 diabetes mellitus (T2DM) and polycystic ovarian syndrome (PCOS) are thought to be in part due to weight reduction. However, the mechanisms by which metformin causes weight loss are unclear. We sought to determine whether circulating levels of the anorectic gut hormone peptide tyrosine tyrosine (PYY) show any correlation with metformin‐induced weight loss. Design and patients We examined the acute effects of orally administrated metformin on fasting PYY levels in eight healthy normal‐weight female subjects. Subsequently, we evaluated the effects of 6 months metformin treatment on fasting PYY levels and anthropometric measurements in 20 women with PCOS. Results In normal‐weight females 10 days’ metformin treatment increased fasting PYY levels (P < 0·01). Similarly, in PCOS subjects metformin treatment increased fasting PYY concentrations (P < 0·05). In both groups a marked variation in PYY increase in response to metformin was observed. Long‐term metformin treatment was associated with improvements in weight (P < 0·05), BMI (P < 0·05), fasting glucose (P < 0·05) and menstrual frequency (P < 0·01). Interestingly, change in PYY levels were correlated with change in waist circumference (r = 0·55, P < 0·05). Conclusions Acute and chronic oral metformin administration increase fasting PYY levels and may contribute to metformin's weight loss effect. Further studies are now required to clarify whether changes in circulating PYY levels in response to metformin treatment can be used to predict which patients will subsequently lose weight long‐term and gain cycle restoration. 相似文献
153.
154.
155.
Karen P Alexander Laura Kristin Newby Manju V Bhapkar Harvey D White Judith S Hochman Matthias E Pfisterer David J Moliterno Eric D Peterson Frans Van de Werf Paul W Armstrong Robert M Califf 《European heart journal》2006,27(13):1558-1564
AIMS: To explore variations in invasive care of the elderly with acute coronary syndromes across international practice. METHODS AND RESULTS: Using combined populations from the SYMPHONY and 2nd SYMPHONY trials, we describe 30-day cardiac catheterization in elderly (> or = 75 years; n = 1794) vs. younger patients (< 75 years; n = 14,043) after multivariable adjustment and by region of enrolment. The use of cardiac catheterization and revascularization were not protocol-specified. Elderly patients (median age 78 years) were more often female and more frequently had hypertension, diabetes, prior myocardial infarction, and prior coronary bypass surgery. Overall, they underwent less cardiac catheterization than younger patients [53 vs. 63%; adjusted OR 0.53 (0.46, 0.60)]. The absolute rate of cardiac catheterization in the elderly varied from 77% (vs. 91% in younger patients) in the US cohort to 27% (vs. 41% in younger patients) in the non-US cohort. Revascularization of elderly who underwent cardiac catheterization was also higher in US than non-US cohorts (71.3 vs. 53.6%). There was a significant interaction between the patient age and the use of catheterization across US and non-US regions of enrolment, as well as differences in the predictors of catheterization in the elderly. Despite these findings, after adjustment, 90-day rates of death and death or myocardial infarction (MI) were not significantly different in elderly who underwent catheterization compared with those who did not. CONCLUSION: Although older age is universally predictive of lower use of cardiac catheterization, marked variation in catheterization of the elderly exists across international practice. Demonstrated differences in patterns of use suggest a lack of consensus regarding optimal use of an invasive strategy in the elderly. 相似文献
156.
Herron KL Lofgren IE Sharman M Volek JS Fernandez ML 《Metabolism: clinical and experimental》2004,53(6):823-830
The influence of a high-cholesterol diet on the atherogenicity of the low-density lipoprotein (LDL) particle was examined by measuring LDL peak diameter and composition, LDL susceptibility to oxidation, and the distribution of cholesterol between LDL subclasses. The crossover intervention randomly assigned 27 premenopausal women and 25 men (18 to 50 years) to an egg (640 mg/d additional dietary cholesterol) or placebo (0 mg/d additional dietary cholesterol) diet for 30 days, followed by a 3-week washout period. Subjects were classified as either hyperresponders (>2.5 mg/dL increase in plasma cholesterol for each 100 mg additional dietary cholesterol consumed) or hyporesponders to dietary cholesterol. Sex was found to have a significant effect on 3 of the parameters examined. LDL peak diameter was significantly larger (P <.005) in females (26.78 +/- 0.59 nm, n = 27) as compared with males (26.52 +/- 0.49 nm, n = 25), regardless of response to dietary cholesterol. The LDL particles of the male participants also had a higher number of triglyceride (TG) and cholesteryl ester (CE) molecules (P <.01); however, cholesterol ester transfer protein (CETP) activity was higher in females (P <.05). Response classification also revealed significant differences in the determination of LDL subclasses. Independent of sex, the LDL-1 particle (P <.05), which is considered to be less atherogenic, was predominant in hyperresponders and this finding was associated with increased cholesterol intake (interactive effect, P <.001). In addition, CETP and lecithin: cholesterol acyltransferase (LCAT) activities were higher in hyperresponders during the egg period (interactive effect, P <.05). Sex, response to cholesterol intake, and diet were not found to affect the susceptibility of LDL to oxidation (P > 0.5). Because LDL peak diameter was not decreased and the larger LDL-1 subclass was greater in hyperresponders following egg intake, these data indicate that the consumption of a high-cholesterol diet does not negatively influence the atherogenicity of the LDL particle. 相似文献
157.
Turner L Conway AJ Jimenez M Liu PY Forbes E McLachlan RI Handelsman DJ 《The Journal of clinical endocrinology and metabolism》2003,88(10):4659-4667
WHO studies provided proof of concept for hormonal male contraception using a prototype androgen-alone regimen. Combined testosterone plus progestin regimens offer more practical promise, but no contraceptive efficacy studies have been completed. The objective of this study was to establish the proof of principle for depot hormonal androgen/progestin combination as a male contraceptive. We performed a contraceptive efficacy study of 55 healthy men in stable fertile relationships seeking a change in contraceptive method. Testosterone (four 200-mg implants, every 4 or 6 months) and 300 mg depot medroxyprogesterone acetate, im, every 3 months were administered. Once sperm output was suppressed (<1 million/ml for 2 consecutive months), men entered a 12-month contraceptive efficacy period, ceasing other contraception. The main outcome measure was contraceptive failure (pregnancy) rate. No pregnancies occurred in 426 person-months (35.5 person-years; 95% confidence limits for contraceptive failure rate, 0-8%/annum), superior to the first year failure rate of condoms, the only reversible male method. Sperm density fell rapidly, so 94% of men entered the efficacy phase by 3 months, with only 2 of 55 (3.6%) men not sufficiently suppressed to enter efficacy. A few men treated with testosterone implants at 6-month intervals demonstrated androgen deficiency symptoms and/or escape of gonadotropin and spermatogenic suppression between months 5 and 6; after a protocol amendment, all men receiving testosterone implants at 4-month intervals avoided androgen deficiency or loss of gonadotropin and sperm output suppression. Recovery was complete (median, 3.6 months to sperm reappearance and 5.0 months to 20 million sperm/ml) in all but one man with an incidental testicular disorder. Discontinuations were for protocol-related reasons (n = 15) or altered personal circumstances (n = 12), but there were no serious adverse effects related to drug exposure. The first male contraceptive efficacy study using a prototype depot androgen/progestin combination demonstrates high contraceptive efficacy with satisfactory short-term safety and recovery of spermatogenesis. Further studies of purpose-developed products are required to extend the overall safety and efficacy experience with depot androgen/progestin combinations, the most promising approach to hormonal male contraception. 相似文献
158.
159.