全文获取类型
收费全文 | 11120篇 |
免费 | 688篇 |
国内免费 | 53篇 |
专业分类
耳鼻咽喉 | 302篇 |
儿科学 | 275篇 |
妇产科学 | 302篇 |
基础医学 | 1573篇 |
口腔科学 | 438篇 |
临床医学 | 913篇 |
内科学 | 2600篇 |
皮肤病学 | 203篇 |
神经病学 | 1254篇 |
特种医学 | 220篇 |
外科学 | 1012篇 |
综合类 | 21篇 |
一般理论 | 6篇 |
预防医学 | 650篇 |
眼科学 | 132篇 |
药学 | 699篇 |
中国医学 | 36篇 |
肿瘤学 | 1225篇 |
出版年
2024年 | 19篇 |
2023年 | 117篇 |
2022年 | 274篇 |
2021年 | 425篇 |
2020年 | 268篇 |
2019年 | 318篇 |
2018年 | 350篇 |
2017年 | 289篇 |
2016年 | 352篇 |
2015年 | 373篇 |
2014年 | 499篇 |
2013年 | 603篇 |
2012年 | 932篇 |
2011年 | 1048篇 |
2010年 | 518篇 |
2009年 | 454篇 |
2008年 | 787篇 |
2007年 | 720篇 |
2006年 | 641篇 |
2005年 | 671篇 |
2004年 | 604篇 |
2003年 | 548篇 |
2002年 | 481篇 |
2001年 | 58篇 |
2000年 | 34篇 |
1999年 | 52篇 |
1998年 | 88篇 |
1997年 | 61篇 |
1996年 | 44篇 |
1995年 | 46篇 |
1994年 | 34篇 |
1993年 | 32篇 |
1992年 | 23篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 2篇 |
1986年 | 15篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 5篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Generali D Berruti A Foroni C Bazzola L Andreis D Allevi G Bersiga A Dogliotti L Fox SB Harris AL Bottini A 《Journal of the National Cancer Institute. Monographs》2011,2011(43):67-70
Breast cancer is a heterogeneous disease. Predictive molecular markers are crucial in patient management, but the only recommended predictive biomarkers are estrogen and progesterone receptors and HER2. There are many new targeted therapies, and although the target pathway expression is readily analyzed on conventional pathology, the dynamic response cannot be assessed and pathway expression is no guarantee it has a major driver role, even if mutated. Selecting therapies requires considering the patient, the molecular characteristics of the tumor, and the microenvironment of the tumor. Thus, the integration of molecular pathology, imaging, and early tumor biological response to therapy may provide evidence of drug activity and allow more rapid changes of therapy. The adaptive response of the tumor is a key resistance mechanism that can be assessed readily in the neoadjuvant setting. Although there are no markers that meet all surrogacy criteria, their use could provide crucial information on mechanisms of drug sensitivity/resistance. Validation of such markers requires a major emphasis on neoadjuvant trials to relate early-biomarker response to outcome. 相似文献
992.
Alessandra M. Correa-Afonso Juliane C. Ciconne-NogueiraJesus D. Pécora Regina G. Palma-Dibb 《Journal of dentistry》2010
Objectives
The aim of this study was to assess the influence of irradiation distance and the use of cooling in the Er:YAG laser efficacy in preventing enamel demineralization.Methods
84 enamel blocks were randomly assigned to seven groups (n = 12): G1: control group – no treatment, G2–G7: experimental groups treated with Er:YAG laser (80 mJ/2 Hz) at different irradiation distances with or without cooling: G2: 4 mm/2 mL; G3: 4 mm/no cooling; G4: 8 mm/2 mL; G5: 8 mm/no cooling; G6: 16 mm/2 mL; G7: 16 mm/no cooling. The samples were submitted to an in vitro pH cycles for 14 days. Next, the specimens were sectioned in sections of 80–100 μm in thickness and the demineralization patterns of prepared slices were assessed using a polarized light microscope. Three samples from each group were analyzed with scanning electronic microscopy. Analysis of variance and the Fisher test were performed for the statistical analysis of the data obtained from the caries-lesion-depth measurements (CLDM) (alpha = 5%).Results
The control group (CLDM = 0.67 mm) was statistically different from group 2 (CLDM = 0.42 mm), which presented a smaller lesion depth, and group 6 (0.91 mm), which presented a greater lesion depth. The results of groups 3 (CLDM = 0.74 mm), 4 (CLDM = 0.70 mm), 5 (CLDM = 0.67 mm) and 7 (CLDM = 0.89 mm) presented statistical similarity. The scanning electronic microscopy analysis showed ablation areas in the samples from groups 4, 5, 6 and 7, and a slightly demineralized area in group 2.Conclusions
It was possible to conclude that Er:YAG laser was efficient in preventing enamel demineralization at a 4-mm irradiation distance using cooling. 相似文献993.
994.
995.
Alberto Ponzone Francesco Porta Alessandro Mussa Alessandra Alluto Silvio Ferraris Marco Spada 《Metabolism: clinical and experimental》2010,59(5):645-652
Conflicting results have been reported concerning the efficacy of tetrahydrobiopterin (BH4), the cofactor of phenylalanine hydroxylase, for reducing phenylalanine (Phe) concentration in phenylketonuria (PKU). We aimed to test quantitatively the effects of BH4 in PKU patients. Seven fully characterized patients were selected among a population of 130 PKU subjects as harboring PKU mutations predicted as BH4 responsive and previously considered responsive to a cofactor challenge. They received a simple Phe (100 mg/kg) and 2 combined Phe (100 mg/kg) and BH4 (20 mg/kg) oral loading tests. Cofactor was administered either before or after the amino acid. The concentrations of Phe, tyrosine (Tyr), and biopterin were measured over 24 hours after loading. The comparative analysis of the loading tests showed that in all patients plasma Phe concentrations peaked within 3 hours, and fell within 24 hours by about 50% in benign, 20% in mild, and 15% in severe phenylalanine hydroxylase deficiency regardless of BH4 administration. A consistent or moderate increase of plasma Tyr, again independent of the cofactor challenge, was observed only in the less severe forms of PAH deficiency. Mean blood biopterin concentration increased 6 times after simple Phe and 34 to 39 times after combined loading tests. The administration of BH4 does not alter Phe and Tyr metabolism in PKU patients. The clearance of plasma Phe after oral loading and, as well as Tyr production, is not related to cofactor challenge but to patient's phenotype. The assessment of BH4 responsiveness by the methods so far used is not reliable, and the occurrence of BH4-responsive forms of PKU still has to be definitely proven. 相似文献
996.
997.
Alessandra Stacchiotti Francesca Bonomini Antonio Lavazza Luigi Fabrizio Rodella Rita Rezzani 《Toxicology》2009
Cyclosporine (CsA) is a universally used immunosuppressive drug which induces adverse side effects in several organs, but its impact on the heart is still controversial. 相似文献
998.
Di Pietro V Gambacurta A Amorini AM Finocchiaro A D'Urso S Ceccarelli L Tavazzi B Giardina B Lazzarino G 《Clinical biochemistry》2008,41(7-8):611-615
ObjectiveTo verify the effect of and to date the unknown T677C mutation of the human N-acetylaspartoacylase (hASPA) gene on the function of the mutated enzyme.Design and methodsWild type and I226T-mutated proteins were expressed and purified from a transformed Escherichia coli colony. Enzymatic activities were measured in the presence of varying substrate concentrations.ResultsWhilst kinetic parameters of wild type hASPA were in line with data in literature, I226T-mutated hASPA showed no enzymatic activity.ConclusionData indicated that this new mutation might be responsible in homozygosis for the phenotype corresponding to Canavan disease. 相似文献
999.
1000.
Dani C Perugi S Benuzzi A Corsini I Bertini G Pratesi S Rubaltelli FF 《Transfusion》2008,48(11):2302-2307
BACKGROUND: More than 90 percent of extremely low‐birth‐weight infants receive one or more transfusions of red blood cells (RBCs). The objective was to assess if RBC transfusions may induce significant changes of plasma acid‐base, electrolyte, and glucose status in extremely preterm infants. STUDY DESIGN AND METHODS: Records of infants with gestational age of less than 31 weeks who were transfused with RBCs during the first week of life were reviewed (n = 61). Blood samples were collected from infants before and after transfusions to evaluate hemoglobin (Hb) level, hematocrit, acid‐base, electrolyte, and glucose status. Then infants were stratified into four groups that received a RBC volume of less than 15, 15 to 20, more than 20 to 25, or more than 25 mL per kg. RESULTS: Infants received 20.7 (±1.5) mL per kg RBCs. After transfusions, a significant increase of pO2 (p < 0.0001) and decrease of Ca2+ (p = 0.047) and glycemia (p < 0.0001) were observed. Infants who were transfused with more than 25 mL per kg were significantly less immature, heavier, and more anemic than infants in other groups. A positive relationship was found between changes of patients' potassium plasma level and K+ intake through RBC transfusion (r = 0.442, p = 0.008). Three (4.9%) infants developed hyperkalemia, one (1.6%) had an exacerbation of his hypocalcemia, and another (1.6%) of his hypoglycemia. CONCLUSIONS: RBC transfusions were effective in correcting anemia in our patients and induced a slight increase of pH and pO2 and decrease of Ca2+ and glycemia, which were not clinically relevant. A linear direct correlation was observed between potassium intake by RBC transfusions and changes of kalemia in our infants, but there was not an increase of K+ plasma level after transfusions. 相似文献