全文获取类型
收费全文 | 18341篇 |
免费 | 1254篇 |
国内免费 | 86篇 |
专业分类
耳鼻咽喉 | 163篇 |
儿科学 | 452篇 |
妇产科学 | 366篇 |
基础医学 | 2496篇 |
口腔科学 | 287篇 |
临床医学 | 2013篇 |
内科学 | 3844篇 |
皮肤病学 | 176篇 |
神经病学 | 1658篇 |
特种医学 | 590篇 |
外国民族医学 | 1篇 |
外科学 | 2572篇 |
综合类 | 209篇 |
一般理论 | 32篇 |
预防医学 | 2167篇 |
眼科学 | 338篇 |
药学 | 1216篇 |
中国医学 | 32篇 |
肿瘤学 | 1069篇 |
出版年
2024年 | 17篇 |
2023年 | 124篇 |
2022年 | 177篇 |
2021年 | 462篇 |
2020年 | 289篇 |
2019年 | 396篇 |
2018年 | 508篇 |
2017年 | 357篇 |
2016年 | 376篇 |
2015年 | 422篇 |
2014年 | 635篇 |
2013年 | 853篇 |
2012年 | 1357篇 |
2011年 | 1525篇 |
2010年 | 818篇 |
2009年 | 668篇 |
2008年 | 1183篇 |
2007年 | 1388篇 |
2006年 | 1209篇 |
2005年 | 1242篇 |
2004年 | 1201篇 |
2003年 | 1101篇 |
2002年 | 997篇 |
2001年 | 219篇 |
2000年 | 167篇 |
1999年 | 218篇 |
1998年 | 181篇 |
1997年 | 121篇 |
1996年 | 113篇 |
1995年 | 113篇 |
1994年 | 80篇 |
1993年 | 83篇 |
1992年 | 89篇 |
1991年 | 85篇 |
1990年 | 86篇 |
1989年 | 83篇 |
1988年 | 70篇 |
1987年 | 55篇 |
1986年 | 44篇 |
1985年 | 52篇 |
1984年 | 59篇 |
1983年 | 54篇 |
1982年 | 55篇 |
1981年 | 54篇 |
1980年 | 31篇 |
1978年 | 32篇 |
1977年 | 22篇 |
1976年 | 31篇 |
1975年 | 23篇 |
1974年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Derendorf H VanderMaelen CP Brickl RS MacGregor TR Eisert W 《Journal of clinical pharmacology》2005,45(7):845-850
Dipyridamole (DP) is an antiplatelet agent that shows decreased oral bioavailability with increased gastric pH that occurs with commonly prescribed antacids. An extended-release (ER) formulation of DP that employs tartaric acid to improve bioavailability of DP in the presence of elevated gastric pH was developed as a combination antiplatelet product with immediate-release aspirin. This crossover-designed study examined the relative bioavailability of DP from the composite product compared to conventional DP tablets during reduced gastric acidity. Gastric pH was increased (pH > 4.0) in 20 healthy subjects with lansoprazole (30 mg/d for 5 days). Dipyridamole systemic exposure over 12 hours was compared after oral administration of a single composite ER capsule (200 mg DP + 25 mg aspirin) versus two 100-mg conventional DP tablets given 6 hours apart combined with 81 mg aspirin. DP relative bioavailability was reduced 53% with conventional tablets compared to the composite buffered ER capsule in reduced gastric acid conditions. Peak DP plasma concentrations were 57% lower with immediate-release tablets compared to the composite formulation with high stomach pH. Substituting generic DP plus low-dose aspirin may be less effective than the buffered DP composite product in patients with concomitant antacid therapies. 相似文献
992.
Huang TH Peng G Kota BP Li GQ Yamahara J Roufogalis BD Li Y 《Toxicology and applied pharmacology》2005,207(2):160-169
Peroxisome proliferator-activated receptor (PPAR)-gamma activators are widely used in the treatment of type 2 diabetes because they improve the sensitivity of insulin receptors. Punica granatum flower (PGF) has been used as an anti-diabetic medicine in Unani medicinal literature. The mechanism of actions is, however, unknown. In the current study, we demonstrated that 6-week oral administration of methanol extract from PGF (500 mg/kg, daily) inhibited glucose loading-induced increase of plasma glucose levels in Zucker diabetic fatty rats (ZDF), a genetic animal model for type 2 diabetes, whereas it did not inhibit the increase in Zucker lean rats (ZL). The treatment did not lower the plasma glucose levels in fasted ZDF and ZL rats. Furthermore, RT-PCR results demonstrated that the PGF extract treatment in ZDF rats enhanced cardiac PPAR-gamma mRNA expression and restored the down-regulated cardiac glucose transporter (GLUT)-4 (the insulin-dependent isoform of GLUTs) mRNA. These results suggest that the anti-diabetic activity of PGF extract may result from improved sensitivity of the insulin receptor. From the in vitro studies, we demonstrated that the PGF extract enhanced PPAR-gamma mRNA and protein expression and increased PPAR-gamma-dependent mRNA expression and activity of lipoprotein lipase in human THP-1-differentiated macrophage cells. Phytochemical investigation demonstrated that gallic acid in PGF extract is mostly responsible for this activity. Thus, our findings indicate that PPAR-gamma is a molecular target for PGF extract and its prominent component gallic acid, and provide a better understanding of the potential mechanism of the anti-diabetic action of PGF. 相似文献
993.
Shenkier TN Voss N Chhanabhai M Fairey R Gascoyne RD Hoskins P Klasa R Morris J O'Reilly SE Pickles T Sehn L Connors JM 《Cancer》2005,103(5):1008-1017
BACKGROUND: The objective of this study was to evaluate the clinical outcome of a population-based cohort of immunocompetent patients with primary central nervous system lymphoma (PCNSL) treated with 3 different strategies over 13 years. METHODS: One hundred twenty-two consecutive patients (median age, 66 years) with PCNSL were identified. Three treatment strategies were employed: 1) whole-brain irradiation with (from January, 1990, to June, 1991) or without (from April, 1995, to December, 1999) cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP)-type chemotherapy (n=50 patients); 2) combined-modality therapy, including 1 g/m2 methotrexate plus whole-brain irradiation (from July, 1991, to March, 1995; n=34 patients); and 3) 8 g/m2 methotrexate alone (from January, 2000, to March, 2003) with whole-brain irradiation reserved for those with progressive disease (n=38 patients). Treatment failure was defined as progressive disease, disease recurrence, death from toxicity or lymphoma, or toxicity that necessitated a change in primary treatment. RESULTS: The median failure-free survival was 7 months, and the median overall survival (OS) was 17 months. The median OS was similar in all 3 eras. In this population-based analysis, one-third of patients did not receive the treatment strategy of the era. Therefore, the data also were analyzed by treatment received. On multivariate analysis (including era of treatment), 3 factors-age > 60 years, lactate dehydrogenase > normal, and omission of methotrexate-were associated significantly with poorer OS (hazard ratio: 2.3, 2.2, and 2.3, respectively). CONCLUSIONS: Outcomes for a general population with PCNSL remained constant despite different treatment strategies over three eras. For the two-thirds of patients who could receive potentially curative treatment, age, lactate dehydrogenase level, and receipt of > or = 1 g/m2 methotrexate appeared to be important determinants of OS. 相似文献
994.
Duthoy W Boterberg T Claus F Ost P Vakaet L Bral S Duprez F Van Landuyt M Vermeersch H De Neve W 《Cancer》2005,104(1):71-82
BACKGROUND: Carcinoma of the paranasal sinuses is rare. Standard therapeutic modalities consist of surgery and radiotherapy (RT). Because of the often advanced stage and the vicinity of optic structures, RT-induced ocular toxicity is a feared side effect of conventional RT. Intensity-modulated radiotherapy (IMRT) is a relatively new technique, which is implemented with the hypothesis that, compared with conventional RT, it would result in a lower rate of ocular toxicity for an equal local control (LC). METHODS: Between 1998 and 2003, 39 consecutive patients received postoperative irradiation by means of IMRT for an adenocarcinoma (n = 31) or squamous cell carcinoma (n = 8) of the paranasal sinuses (n = 36) or nasal cavity (n = 3). T-classification was T2 in 41%, T3 in 15%, T4a in 23%, and T4b in 21% of patients. Invasion through the cribriform plate was seen in 11 patients. Orbital invasion was present in 36% of patients. The median delivered dose was 70 gray (Gy) (range, 60-70 Gy). The authors compared the overall survival (OS) and LC of the patients with a historic cohort (HC) (n = 30), treated with conventional or 3-dimensional conformal RT. RESULTS: The median follow-up was 31 months. The actuarial OS rates were 68% at 2 years and 59% at 4 years. The actuarial LC rates were 73% at 2 years and 68% at 4 years. Invasion through the cribriform plate was a significant prognostic factor for LC and OS, with a median time to local disease recurrence of 7 months if present, and a 2-year LC rate of 90% if not present. In the comparison between the IMRT and HC groups, no significant differences were found for LC and OS. Acute toxicity was mild. Two patients developed decreased vision after RT. No RT-induced blindness was observed. CONCLUSIONS: Postoperative IMRT for sinonasal carcinoma resulted in good LC, with a low acute toxicity and no RT-induced blindness. 相似文献
995.
Low-level environmental lead exposure and children's intellectual function: an international pooled analysis 总被引:25,自引:0,他引:25
Lanphear BP Hornung R Khoury J Yolton K Baghurst P Bellinger DC Canfield RL Dietrich KN Bornschein R Greene T Rothenberg SJ Needleman HL Schnaas L Wasserman G Graziano J Roberts R 《Environmental health perspectives》2005,113(7):894-899
Lead is a confirmed neurotoxin, but questions remain about lead-associated intellectual deficits at blood lead levels < 10 microg/dL and whether lower exposures are, for a given change in exposure, associated with greater deficits. The objective of this study was to examine the association of intelligence test scores and blood lead concentration, especially for children who had maximal measured blood lead levels < 10 microg/dL. We examined data collected from 1,333 children who participated in seven international population-based longitudinal cohort studies, followed from birth or infancy until 5-10 years of age. The full-scale IQ score was the primary outcome measure. The geometric mean blood lead concentration of the children peaked at 17.8 microg/dL and declined to 9.4 microg/dL by 5-7 years of age; 244 (18%) children had a maximal blood lead concentration < 10 microg/dL, and 103 (8%) had a maximal blood lead concentration < 7.5 microg/dL. After adjustment for covariates, we found an inverse relationship between blood lead concentration and IQ score. Using a log-linear model, we found a 6.9 IQ point decrement [95% confidence interval (CI), 4.2-9.4] associated with an increase in concurrent blood lead levels from 2.4 to 30 microg/dL. The estimated IQ point decrements associated with an increase in blood lead from 2.4 to 10 microg/dL, 10 to 20 microg/dL, and 20 to 30 microg/dL were 3.9 (95% CI, 2.4-5.3), 1.9 (95% CI, 1.2-2.6), and 1.1 (95% CI, 0.7-1.5), respectively. For a given increase in blood lead, the lead-associated intellectual decrement for children with a maximal blood lead level < 7.5 microg/dL was significantly greater than that observed for those with a maximal blood lead level > or = 7.5 microg/dL (p = 0.015). We conclude that environmental lead exposure in children who have maximal blood lead levels < 7.5 microg/dL is associated with intellectual deficits. 相似文献
996.
Almeida NA de Sousa JT Bachion MM Silveira Nde A 《Revista latino-americana de enfermagem》2005,13(1):52-58
This study aimed to evaluate the effect of respiration and relaxation techniques on pain and anxiety during labor. Seventeen parturients (Control Group--CG) received routine care and nineteen (Experimental Group--EG) were orientated and stimulated to perform respiration and relaxation techniques. Pain was evaluated by means of the visual analogy scale and anxiety by means of the anxiety inventories--trait and state. Pain intensity increased along with the evolution of the delivery for both groups. In the latent phase, anxiety levels were low for both groups; in the active phase, levels were average for CG and low for EG. In the transition phase, levels were average and, in the immediate post-labor phase, low for both groups. It was concluded that the techniques used did not reduce pain intensity, but provided EG with lower anxiety levels for a longer time during labor. 相似文献
997.
998.
999.
1000.