全文获取类型
收费全文 | 6198篇 |
免费 | 608篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 42篇 |
儿科学 | 137篇 |
妇产科学 | 179篇 |
基础医学 | 961篇 |
口腔科学 | 116篇 |
临床医学 | 712篇 |
内科学 | 1295篇 |
皮肤病学 | 177篇 |
神经病学 | 448篇 |
特种医学 | 210篇 |
外科学 | 810篇 |
综合类 | 74篇 |
一般理论 | 3篇 |
预防医学 | 593篇 |
眼科学 | 100篇 |
药学 | 500篇 |
中国医学 | 20篇 |
肿瘤学 | 449篇 |
出版年
2023年 | 72篇 |
2022年 | 142篇 |
2021年 | 250篇 |
2020年 | 169篇 |
2019年 | 180篇 |
2018年 | 206篇 |
2017年 | 172篇 |
2016年 | 169篇 |
2015年 | 200篇 |
2014年 | 255篇 |
2013年 | 327篇 |
2012年 | 489篇 |
2011年 | 488篇 |
2010年 | 276篇 |
2009年 | 217篇 |
2008年 | 372篇 |
2007年 | 403篇 |
2006年 | 356篇 |
2005年 | 343篇 |
2004年 | 331篇 |
2003年 | 281篇 |
2002年 | 242篇 |
2001年 | 97篇 |
2000年 | 59篇 |
1999年 | 64篇 |
1998年 | 47篇 |
1997年 | 27篇 |
1996年 | 24篇 |
1995年 | 31篇 |
1994年 | 31篇 |
1993年 | 35篇 |
1992年 | 31篇 |
1991年 | 24篇 |
1990年 | 35篇 |
1989年 | 27篇 |
1988年 | 17篇 |
1987年 | 24篇 |
1986年 | 18篇 |
1985年 | 24篇 |
1984年 | 31篇 |
1983年 | 22篇 |
1982年 | 24篇 |
1981年 | 26篇 |
1980年 | 22篇 |
1979年 | 20篇 |
1978年 | 14篇 |
1977年 | 10篇 |
1975年 | 12篇 |
1974年 | 14篇 |
1973年 | 8篇 |
排序方式: 共有6826条查询结果,搜索用时 0 毫秒
871.
T-1213C polymorphism of estrogen receptor beta is associated with low bone mineral density and osteoporotic fractures 总被引:1,自引:0,他引:1
Osteoporosis is a complex disease with a strong genetic component, but the genes involved are poorly defined. To determine whether estrogen receptor beta (ESR2) gene is an osteoporosis risk gene, we examined its association with bone mineral density (BMD) and fracture risk. Using a gene-based approach, a set of 12 polymorphisms of ESR2 was studied in 752 case-control pairs of southern Chinese in ethnicity. Among all polymorphisms, the most significant relation with BMD and fracture risk was observed with T-1213C. Subjects with low BMD had a higher frequency of the variant C allele of T-1213C (cases 11.4%, control 8.4%, P = 0.02). The C allele was associated with 4% reduction in BMD at both the spine and hip in women, and 11% reduction in spine BMD and 9% reduction in hip BMD in men. Similar results were seen with SNP haplotype analysis. Subjects with the C allele of T-1213C were associated with higher risks of osteoporosis and BMD T scores < or = -2.5 (odds ratios: 2.2 at spine and 3.5 at femoral neck for women; 3.5 at lumbar spine for men). Postmenopausal women carrying this C allele were associated with 2.22-fold increased risk of osteoporotic fractures (95% confidence interval 1.26-4.25) even after adjusting for BMD. In conclusion, ESR2 is involved in BMD determination in both sexes. The T-1213C polymorphism influences the risk of fracture in postmenopausal women independent of BMD. 相似文献
872.
We report a rare presentation of a nested variant of urothelial carcinoma with liver and bone metastases in a 74-year-old man admitted to the hospital with bilateral hydronephrosis and acute renal failure. At cystoscopy, both ureters were obstructed, with the right ureter narrowed along its entire length. Subsequent histopathologic examination from the ureteral resection revealed nested variant of urothelial carcinoma. Bilateral stents were placed, and the patient survived 12 months with a good partial response to chemotherapy. A total of 76 cases of nested variant of urothelial carcinoma have been reported worldwide. Our patient was the first, to our knowledge, to present with bilateral hydronephrosis and tumor extension along one ureter. 相似文献
873.
874.
López-Bermejo A Khosravi J Fernández-Real JM Hwa V Pratt KL Casamitjana R Garcia-Gil MM Rosenfeld RG Ricart W 《Diabetes》2006,55(8):2333-2339
IGF-binding protein (IGFBP)-related protein 1 (IGFBP-rP1) has been shown to bind both IGFs and insulin, albeit with low affinity, and to inhibit insulin signaling. We hypothesized that IGFBP-rP1 is associated with insulin resistance and components of the IGF system in humans. To this aim, a cross-sectional study was conducted in 113 nondiabetic and 43 type 2 diabetic men. Insulin sensitivity (insulin sensitivity index [S(i)] from intravenous glucose tolerance tests in nondiabetic subjects, or the rate constant for disappearance of glucose [K(ITT)] from insulin tolerance tests in type 2 diabetic subjects), circulating IGFBP-rP1 (from enzyme-linked immunosorbent assay), adiponectin (from radioimmunoassay), C-reactive protein (CRP; from immunoturbidimetry), soluble tumor necrosis factor receptor 2 (sTNFR2; from enzyme-amplified sensitivity immunoassay), and IGF system parameters (IGF-I, free IGF-I, and IGFBP-1 from immunoradiometric assay) were assessed in all subjects. Among nondiabetic men, those in the highest quartile for circulating IGFBP-rP1 exhibited decreased S(i) and adiponectin (both P < 0.01) as well as increased CRP and sTNFR2 (both P < 0.05). Circulating IGFBP-rP1 was also found to be increased in previously undiagnosed type 2 diabetic patients (P = 0.01) but not in known type 2 diabetic patients receiving pharmacological therapy. Although no changes in IGF system components were evident by IGFBP-rP1 quartiles in nondiabetic subjects, independent positive associations of IGFBP-rP1 with circulating fasting IGFBP-1 were evident after adjustment for insulin resistance parameters in both nondiabetic and type 2 diabetic subjects, with IGFBP-rP1 explaining 2 and 11% of IGFBP-1 variance, respectively. In additional multivariate analyses, S(i), sTNFR2, and age stood as independent predictive variables of IGFBP-rP1 (together explaining 18% of its variance) in nondiabetic subjects, and BMI became the only independent predictive variable of IGFBP-rP1 (explaining 26% of its variance) in type 2 diabetic men. These findings show for the first time that circulating IGFBP-rP1 is increased with insulin resistance, and they also suggest novel interactions between IGFBP-rP1 and the IGF system in humans. 相似文献
875.
Yao-Borengasser A Rasouli N Varma V Miles LM Phanavanh B Starks TN Phan J Spencer HJ McGehee RE Reue K Kern PA 《Diabetes》2006,55(10):2811-2818
Lipin-alpha and -beta are the alternatively spliced gene products of the Lpin1 gene, whose product lipin is required for adipocyte differentiation. Lipin deficiency causes lipodystrophy, fatty liver, and insulin resistance in mice, whereas adipose tissue lipin overexpression results in increased adiposity but improved insulin sensitivity. To assess lipin expression and its relation to insulin resistance in humans, we examined lipin-alpha and -beta mRNA levels in subjects with normal or impaired glucose tolerance. We found higher expression levels of both lipin isoforms in lean, insulin-sensitive subjects. When compared with normal glucose-tolerant subjects, individuals with impaired glucose tolerance were more insulin resistant, demonstrated higher levels of intramyocellular lipids (IMCLs), and expressed approximately 50% lower levels of lipin-alpha and -beta. In addition, there was a strong inverse correlation between adipose tissue lipin expression and muscle IMCLs but no evidence for an increase in muscle lipid oxidation. After treatment of the impaired glucose-tolerant subjects with insulin sensitizers for 10 weeks, pioglitazone (but not metformin) resulted in a 60% increase in the insulin sensitivity index (Si) and a 32% decrease in IMCLs (both P < 0.01), along with an increase in lipin-beta (but not lipin-alpha) expression by 200% (P < 0.005). Lipin expression in skeletal muscle, however, was not related to obesity or insulin resistance. Hence, high adipose tissue lipin expression is found in insulin-sensitive subjects, and lipin-beta expression increases following treatment with pioglitazone. These results suggest that increased adipogenesis and/or lipogenesis in subcutaneous fat, mediated by the LPIN1 gene, may prevent lipotoxicity in muscle, leading to improved insulin sensitivity. 相似文献
876.
Vivian E. Shih Eliot L. Berson Marita Gargiulo 《Clinica chimica acta; international journal of clinical chemistry》1981,113(3):243-251
Five patients with gyrate atrophy of the choroid and retina showed a 60% or greater decline in plasma ornithine levels during a five week trial of a low protein (10–15 g/day), low arginine (0.50–0.75 g/day) diet supplemented with essential amino acids and pyridoxine administration. These declines in plasma ornithine levels were seen in Patients 1–4 with the pyridoxine non-responsive variant and in Patient 5 with the pyridoxine responsive variant. No harmful systemic side effects were noted. Patients 1–4 continued on a modified low protein (20–35 g/day), low arginine (1.25–1.75 g/day) diet as tolerated and Patient 5 on pyridoxine alone. After one year no improvement was observed in visual acuities, visual fields, final dark adapted thresholds and full field electroretinograms for four patients. In contrast to the other four patients, Patient 3, with relatively poor control of plasma ornithine levels, showed signs of progression of the chorioretinal atrophy and further reduction of electroretinographic responses. Patients 1–4 continue on the dietary regimen and Patient 5 on pyridoxine alone to determine whether any lowering of plasma ornithine levels will modify the course of their ocular disease. 相似文献
877.
878.
Black widow spider venom (BWSW) elicited a prolonged tonic contraction of guinea-pig ileum which abolished the nicotine-induced contraction; however, the subsequent acetylcholine stimulation was found to be unchanged. These findings indicate a depletion of nerve terminal transmtiters caused by BWSW without a disruption of the muscle contractile mechanism. Following the BWSW-induced contraction, the stimulation to 5-hydroxytryptamine (5-HT) was found to be abolished. This abolishment indicates a mediation of 5-HT-induced smooth muscle contraction in the nerve rather than the muscle. 相似文献
879.
880.