全文获取类型
收费全文 | 577篇 |
免费 | 68篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 22篇 |
妇产科学 | 6篇 |
基础医学 | 68篇 |
口腔科学 | 10篇 |
临床医学 | 51篇 |
内科学 | 145篇 |
皮肤病学 | 30篇 |
神经病学 | 11篇 |
特种医学 | 70篇 |
外科学 | 28篇 |
综合类 | 18篇 |
预防医学 | 47篇 |
药学 | 32篇 |
肿瘤学 | 126篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 5篇 |
2019年 | 6篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 2篇 |
2015年 | 12篇 |
2014年 | 7篇 |
2013年 | 16篇 |
2012年 | 13篇 |
2011年 | 20篇 |
2010年 | 13篇 |
2009年 | 21篇 |
2008年 | 29篇 |
2007年 | 36篇 |
2006年 | 27篇 |
2005年 | 23篇 |
2004年 | 14篇 |
2003年 | 21篇 |
2002年 | 18篇 |
2001年 | 16篇 |
2000年 | 15篇 |
1999年 | 19篇 |
1998年 | 25篇 |
1997年 | 17篇 |
1996年 | 32篇 |
1995年 | 8篇 |
1994年 | 18篇 |
1993年 | 11篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 13篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 17篇 |
1984年 | 7篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1973年 | 3篇 |
1956年 | 1篇 |
排序方式: 共有668条查询结果,搜索用时 31 毫秒
31.
van Noesel MM van Bezouw S Salomons GS Voûte PA Pieters R Baylin SB Herman JG Versteeg R 《Cancer research》2002,62(7):2157-2161
TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) induces apoptosis in a large variety of cancer cells but not in most normal human cells. This feature makes TRAIL, a potential antitumor agent. TRAIL can bind to four different receptors, two pro-apoptotic death receptors (DRs), DR4 and DR5, and two antiapoptotic decoy receptors (DcRs), DcR1 and DcR2. Normal cells express all four of the receptors. The increased TRAIL sensitivity of tumor cells has been postulated to result from the lack of DcR expression. We studied the tumor-specific down-regulation of the TRAIL receptors DcR1 and DcR2, as well as DR4 and DR5, in a group of pediatric tumor cell lines [nine neuroblastoma and three peripheral primitive neuro-ectodermal tumors (PNETs)] and three cell lines from adult tumors. Lack of expression of DcR1 and DcR2 was widespread (13 of the 15 cell lines and 10 of 15, respectively), both in the adult tumor cell lines and in the pediatric tumor lines. DR4 and DR5 were expressed in 8 of 15 and 12 of 15 cell lines, respectively. To understand the tumor-specific down-regulation of the TRAIL receptors, the promoter regions were studied for possible methylation changes of their CpG islands. All normal tissues were completely unmethylated, whereas in the tumor cell lines, we found frequent hypermethylation of the promoter. For DcR1 and DcR2, we found dense hypermethylation in 9 (69%) of 13 and 9 (90%) of 10 of nonexpressing cell lines, respectively. DR4 and DR5 were methylated in 5 (71%) of 7 and 2 (67%) of 3 nonexpressing cell lines, respectively. Treatment with the demethylating agent 5-aza-2'deoxycytidine resulted in partial demethylation and restored mRNA expression. In addition, we performed mutation analysis of the death domains of DR4 and DR5 by sequencing exon 9. Mutations were not present in any of the neuroblastoma or PNET cell lines. A panel of 28 fresh neuroblastoma tumor samples also lacked expression of DcR1 and DcR2 in 85 and 74% of cases, respectively. Hypermethylation was observed in 6 (21%) of 28 for DcR1 and 7 (25%) of 28 for DcR2. DR4 and DR5 were both expressed in 22 of 28 tumors, and no promoter methylation was observed. These data suggest that hypermethylation of the promoters of DcR1 and DcR2 is important in the down-regulation of expression in neuroblastoma and other tumor types. 相似文献
32.
DL DSouza SB Heinze RJ Dowling 《Journal of Medical Imaging and Radiation Oncology》2006,50(3):246-248
Lung cancer is not commonly known to metastasise to the perirenal space, with only five such cases previously published. We present an unusual case of perirenal lung metastases manifesting as diffuse perinephric stranding which to our knowledge has not been described before. 相似文献
33.
DI Wilson SB Britton C McKeown D Kelly IE Cross S Strobel PJ Scambler 《Archives of disease in childhood》1993,68(2):187-189
A boy with the dysmorphic features of Noonan's syndrome and pulmonary valve stenosis who had evidence of hypoparathyroidism and abnormal T lymphocyte numbers in the neonatal period is reported. He had a normal karyotype but molecular analysis revealed a submicroscopic deletion within chromosome 22q11, the region deleted in DiGeorge syndrome. Thus this child has both Noonan's syndrome and DiGeorge syndrome; 22q11 is a candidate region for a gene defective in Noonan's syndrome. 相似文献
34.
35.
36.
37.
38.
Villamor E Saathoff E Bosch RJ Hertzmark E Baylin A Manji K Msamanga G Hunter DJ Fawzi WW 《The American journal of clinical nutrition》2005,81(4):880-888
BACKGROUND: Linear growth retardation and wasting are common in children born to HIV-infected women. Inexpensive interventions that could improve the postnatal growth pattern of such children are needed. OBJECTIVE: The objective was to examine the effect of supplementing HIV-infected women with multivitamins or vitamin A and beta-carotene, during and after pregnancy, on the growth of their children during the first 2 y of life. DESIGN: We conducted a randomized placebo-controlled trial in 886 mother-infant pairs in Tanzania. At the first prenatal visit, HIV-infected women were randomly assigned to 1 of 4 daily oral regimens in a 2 x 2 factorial fashion: multivitamins (MV: thiamine, riboflavin, vitamin B-6, niacin, vitamin B-12, vitamin C, vitamin E, and folic acid), preformed vitamin A + beta-carotene (VA/BC), MV including VA/BC, or placebo. Supplementation continued during the first 2 y postpartum and thereafter. Children were weighed and measured monthly, and all received vitamin A supplements after 6 mo of age per the standard of care. RESULTS: Multivitamins had a significant positive effect on attained weight (459 g; 95% CI: 35, 882; P = 0.03) and on weight-for-age (0.42; 95% CI: 0.07, 0.77; P = 0.02) and weight-for-length (0.38; 95% CI: 0.07, 0.68; P = 0.01) z scores at 24 mo. VA/BC seemed to reduce the benefits of MV on these outcomes. No significant effects were observed on length, midupper arm circumference, or head circumference. CONCLUSION: Supplementation of HIV-infected women with multivitamins (vitamin B complex, vitamin C, and vitamin E) during pregnancy and lactation is an effective intervention for improving ponderal growth in children. 相似文献
39.
Decreased consumption of dried mature beans is positively associated with urbanization and nonfatal acute myocardial infarction 总被引:1,自引:0,他引:1
Kabagambe EK Baylin A Ruiz-Narvarez E Siles X Campos H 《The Journal of nutrition》2005,135(7):1770-1775
Legumes may protect against myocardial infarction (MI). The objective of this study was to determine whether consumption of dried mature beans (referred to as beans), the main legume in Latin America, is associated with MI. The cases (n = 2119) were survivors of a first acute MI and were matched by age, sex, and area of residence to randomly selected population controls (n = 2119) in Costa Rica. Dietary intake was assessed with a validated FFQ. Of the population, 69% consumed > or = 1 serving of beans/d (1 serving = one-third cup of cooked beans, approximately 86 g). Consumption of > or = 1 serving/d was significantly higher (P < 0.001) in rural (81%) than in urban (65%) areas. Individuals who never eat dried beans or whose consumption was < 1 time/mo were classified as nonconsumers. Compared with nonconsumers, intake of 1 serving of beans/d was inversely associated with MI in analyses adjusted for smoking, history of diabetes, history of hypertension, abdominal obesity, physical activity, income, intake of alcohol, total energy, saturated fat, trans fat, polyunsaturated fat, and cholesterol [odds ratio (OR) = 0.62; 95% CI: 0.45-0.88]. No further protection was observed with increased number of servings/d (OR = 0.73; 95% CI: 0.52-1.03 for > 1 serving/d). In summary, we found that consumption of 1 serving of beans/d is associated with a 38% lower risk of MI. No additional protection was observed at intakes > 1 serving/d. These findings are timely given the trend toward increased obesity, cardiovascular disease, and a reduction in the intake of beans in Latin American countries. 相似文献
40.