全文获取类型
收费全文 | 2662篇 |
免费 | 136篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 21篇 |
儿科学 | 77篇 |
妇产科学 | 82篇 |
基础医学 | 357篇 |
口腔科学 | 63篇 |
临床医学 | 237篇 |
内科学 | 566篇 |
皮肤病学 | 56篇 |
神经病学 | 298篇 |
特种医学 | 18篇 |
外科学 | 292篇 |
综合类 | 13篇 |
一般理论 | 1篇 |
预防医学 | 219篇 |
眼科学 | 161篇 |
药学 | 161篇 |
中国医学 | 12篇 |
肿瘤学 | 184篇 |
出版年
2024年 | 2篇 |
2023年 | 16篇 |
2022年 | 18篇 |
2021年 | 115篇 |
2020年 | 60篇 |
2019年 | 82篇 |
2018年 | 111篇 |
2017年 | 66篇 |
2016年 | 61篇 |
2015年 | 71篇 |
2014年 | 115篇 |
2013年 | 129篇 |
2012年 | 215篇 |
2011年 | 244篇 |
2010年 | 157篇 |
2009年 | 92篇 |
2008年 | 144篇 |
2007年 | 178篇 |
2006年 | 146篇 |
2005年 | 174篇 |
2004年 | 158篇 |
2003年 | 143篇 |
2002年 | 134篇 |
2001年 | 7篇 |
2000年 | 12篇 |
1999年 | 20篇 |
1998年 | 24篇 |
1997年 | 10篇 |
1996年 | 19篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1963年 | 2篇 |
排序方式: 共有2818条查询结果,搜索用时 31 毫秒
991.
992.
André Gottås Marianne Arnestad Per Steinar Halvorsen Liliana C. Bachs Gudrun Høiseth 《Forensic Toxicology》2016,34(2):277-285
Vitreous humor (VH) is an alternative matrix for drug analysis in forensic toxicology. However, little is known about the distribution of xenobiotics, such as opioids, into VH in living organisms. The aim of this study was to simultaneously measure heroin and metabolite concentrations in blood and VH after injection of heroin in a living pig model. Six pigs were under non-opioid anesthesia during the surgical operation and experiment. Ocular microdialysis was used to acquire dialysate from VH, and a venous catheter was used for blood sampling. Twenty milligrams of heroin was injected intravenously with subsequent sampling of blood and dialysate for 6 h. The samples were analyzed by ultra-performance liquid chromatography–tandem mass spectrometry. Heroin was not detected in VH; 6-monoacetylmorphine (6-MAM) and morphine were first detected in VH after 60 min. The morphine concentration in VH thereafter increased throughout the experimental period. For 6-MAM, C max was reached after 230 min in VH. In blood, 6-MAM reached C max after 0.5 min, with a subsequent biphasic elimination phase. The blood and VH 6-MAM concentrations reached equilibrium after 2 h. In blood, morphine reached C max after 4.3 min, with a subsequent slower elimination than 6-MAM. The blood and VH morphine concentrations were in equilibrium about 6 h after injection of heroin. In conclusion, both 6-MAM and morphine showed slow transport into VH; detection of 6-MAM in VH did not necessarily reflect a recent intake of heroin. Because postmortem changes are expected to be small in VH, these experimental results could assist the interpretation of heroin deaths. 相似文献
993.
Lilian Tzivian Martha Dlugaj Angela Winkler Frauke Hennig Kateryna Fuks Dorothee Sugiri 《Journal of toxicology and environmental health. Part A》2016,79(22-23):1057-1069
ABSTRACTInvestigations of adverse effects of air pollution (AP) and ambient noise on cognitive functions are apparently scarce, and findings seem to be inconsistent. The aim of this study was to examine the associations of long-term exposure to AP and traffic noise with cognitive performance. At the second examination of the population-based Heinz Nixdorf Recall study (2006–2008), cognitive performance was evaluated in 4086 participants. Long-term residential exposure to size-specific particulate matter (PM) and nitrogen oxides (NOx) with land use regression, to and traffic noise (weighted 24-h (LDEN) and nighttime (LNIGHT) means), was assessed according to the European Union (EU) Directive 2002/49/EC. Multiple regression models were calculated for the relationship of environmental exposures with a global cognitive score (GCS) and in five cognitive subtests, using single- and two-exposure models. In fully adjusted models, several AP metrics were negatively associated with four of five subtests and with GCS. For example, an interquartile range increase in PM2.5 was correlated with verbal fluency, labyrinth test, and immediate and delayed verbal recall. A 10 dB(A) elevation in LDEN and LNIGHT was associated with GCS. Similar but not significant associations were found for the cognitive subtests. In two-exposure models including noise and air pollution simultaneously, the associations did not change markedly for air pollution, but attenuated numerically for noise. Long-term exposures to AP and traffic noise are negatively correlated with subtests related to memory and executive functions. There appears to be little evidence for mutual confounding. 相似文献
994.
Ana M. Vasconcelos Michiel A. Daam Liliana R. A. dos Santos Ana L. M. Sanches Cristiano V. M. Araújo Evaldo L. G. Espíndola 《Ecotoxicology (London, England)》2016,25(3):500-509
As compared to other aquatic organism groups, relatively few studies have been conducted so far evaluating the toxicity of pesticides to amphibians. This may at least partly be due to the fact that regulations for registering pesticides usually do not require testing amphibians. The sensitivity of amphibians is generally considered to be covered by that based on toxicity tests with other aquatic organisms (e.g. fish) although the impact of a pesticide on amphibians may be very different. In the present study, acute and chronic laboratory tests were conducted to evaluate the acute and chronic toxicity of abamectin (as Vertimec® 18EC) to bullfrog (Lithobates catesbeianus) tadpoles. Acute tests were conducted at two tadpole stages (Gosner stage 21G and 25G) and avoidance tests were also conducted with stage Gosner stage 21G tadpoles. Calculated acute toxicity values were greater than those reported for standard fish test species, hence supporting the use of fish toxicity data as surrogates for amphibians in acute risk assessments. Given the limited number and extent of available amphibian toxicity studies, however, research needs to increase our understanding of pesticide toxicity to amphibians are discussed. 相似文献
995.
Satta S Perseu L Moi P Asunis I Cabriolu A Maccioni L Demartis FR Manunza L Cao A Galanello R 《Haematologica》2011,96(5):767-770
The persistence of high fetal hemoglobin level in adults may ameliorate the clinical phenotype of beta-thalassemia and sickle cell anemia. Several genetic variants responsible for hereditary persistence of fetal hemoglobin, linked and not linked to the beta globin gene cluster, have been identified in patients and in normal individuals. Monoallelic loss of KLF1, a gene with a key role in erythropoiesis, has been recently reported to be responsible for persistence of high levels of fetal hemoglobin. In a Sardinian family, high levels of HbF (22.1-30.9%) were present only in compound heterozygotes for the S270X nonsense and K332Q missense mutations, while the isolated S270X nonsense (haploinsufficiency) or K332Q missense mutation were associated with normal HbF levels (<1.5%). Functionally, the K332Q Klf1 mutation impairs binding to the BCl11A gene and activation of the γ- and β-globin promoters. Moreover, we report for the first time the association of KLF1 mutations with very high levels of zinc protoporphyrin. 相似文献
996.
Pezzin LE Feldman PH Mongoven JM McDonald MV Gerber LM Peng TR 《Journal of general internal medicine》2011,26(3):280-286
Background
Blood pressure (BP) control remains elusive for many Americans. Although home health nurses are uniquely positioned to help vulnerable individuals achieve BP control, hypertension (HTN) management has not been a high priority in post-acute care. 相似文献997.
998.
Pitroski CE Cossio SL Koehler-Santos P Graudenz M Prolla JC Ashton-Prolla P 《International journal of colorectal disease》2011,26(7):841-846
Introduction
MUTYH-associated polyposis (MAP) is an autosomal recessive cancer predisposition syndrome associated with the development of colorectal tumors and colonic polyps at an early age. MAP syndrome is associated to germline biallelic mutations in the MUTYH gene which lead to deficient DNA repair through the base-excision repair system and accumulation of G:C→T:A transversions. Occurrence of such mutations in oncogenes and tumor suppressor genes drives colorectal carcinogenesis and is associated with the development of colonic polyps. Two common mutations, p.Y179C and p.G396D, are present in approximately 70–80% of MAP in European families with identified MUTYH germline mutations. The aim of this study was to assess the frequency of the germline MUTYH mutations p.Y179C and p.G396D in Brazilian patients with MAP and other hereditary colorectal cancer (CRC) phenotypes, as well as in sporadic CRC cases. 相似文献999.
Paget V Legedz L Gaudebout N Girerd N Bricca G Milon H Vincent M Lantelme P 《Hypertension》2011,57(4):702-709
Natriuretic peptides are controregulatory hormones associated with cardiac remodeling, namely, left ventricular hypertrophy and systolic/diastolic dysfunction. We intended to address the prognostic value of N-terminal pro-brain natriuretic peptide (NT-proBNP) in hypertension. We prospectively studied the relationship between plasma NT-proBNP and all-cause mortality in 684 hypertensive patients with no history or symptoms of heart failure referred for hypertension workup in our institution from 1998 to 2008. After a mean duration of 5.7 years, we observed 40 deaths (1.04 deaths per 100 patients per year). After adjustment for traditional cardiovascular risk factors, including ambulatory blood pressure and serum creatinine, the risk for all-cause mortality more than doubled with each increment of 1 log NT-proBNP (hazard ratio: 2.33 [95% CI: 1.36 to 3.96]). The risk of death of patients with plasma NT-proBNP≥133 pg/mL (third tertile of the distribution) was 3.3 times that of patients with values<50.8 pg/mL (first tertile; hazard ratio: 3.30 [95% CI: 0.90 to 12.29]). This predictive value was independent of, and superior to, that of 2 ECG indexes of left ventricular hypertrophy, the Sokolov-Lyon index and the amplitude of the R wave in lead aVL. In addition, it persisted in patients without ECG left ventricular hypertrophy, which allowed refining risk stratification in this relatively low-risk patient category. In this large sample of hypertensive patients, plasma NT-proBNP appeared as a strong prognostic marker. This performance, together with the ease of measurement, low cost, and widespread availability of NT-proBNP test kits, should prompt a wide use of this marker for risk stratification in hypertension. 相似文献
1000.