全文获取类型
收费全文 | 6250篇 |
免费 | 462篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 29篇 |
儿科学 | 252篇 |
妇产科学 | 170篇 |
基础医学 | 881篇 |
口腔科学 | 145篇 |
临床医学 | 658篇 |
内科学 | 1283篇 |
皮肤病学 | 90篇 |
神经病学 | 616篇 |
特种医学 | 112篇 |
外科学 | 623篇 |
综合类 | 40篇 |
一般理论 | 2篇 |
预防医学 | 741篇 |
眼科学 | 108篇 |
药学 | 412篇 |
中国医学 | 5篇 |
肿瘤学 | 559篇 |
出版年
2024年 | 9篇 |
2023年 | 80篇 |
2022年 | 113篇 |
2021年 | 220篇 |
2020年 | 169篇 |
2019年 | 194篇 |
2018年 | 202篇 |
2017年 | 184篇 |
2016年 | 174篇 |
2015年 | 206篇 |
2014年 | 251篇 |
2013年 | 362篇 |
2012年 | 466篇 |
2011年 | 526篇 |
2010年 | 257篇 |
2009年 | 236篇 |
2008年 | 417篇 |
2007年 | 426篇 |
2006年 | 384篇 |
2005年 | 375篇 |
2004年 | 311篇 |
2003年 | 274篇 |
2002年 | 283篇 |
2001年 | 48篇 |
2000年 | 48篇 |
1999年 | 46篇 |
1998年 | 46篇 |
1997年 | 37篇 |
1996年 | 35篇 |
1995年 | 22篇 |
1994年 | 23篇 |
1993年 | 12篇 |
1992年 | 25篇 |
1991年 | 17篇 |
1990年 | 19篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 25篇 |
1986年 | 10篇 |
1985年 | 15篇 |
1984年 | 15篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1974年 | 10篇 |
1973年 | 8篇 |
1970年 | 11篇 |
1968年 | 8篇 |
排序方式: 共有6726条查询结果,搜索用时 11 毫秒
41.
Teun P De Boer Bart Kok Kirsten I E Neuteboom Nicole Spieker Jochum De Graaf Olivier H J Destrée Martin B Rook Toon A B Van Veen Habo J Jongsma Marc A Vos Jacques M T De Bakker Marcel A G Van Der Heyden 《Developmental dynamics》2005,233(3):864-871
Connexin-containing gap junctions play an essential role in vertebrate development. More than 20 connexin isoforms have been identified in mammals. However, the number identified in Xenopus trails with only six isoforms described. Here, identification of a new connexin isoform from Xenopus laevis is described. Connexin40.4 was found by screening expressed sequence tag databases and carrying out polymerase chain reaction on genomic DNA. This new connexin has limited amino acid identity with mammalian (<50%) connexins, but conservation is higher (approximately 62%) with fish. During Xenopus laevis development, connexin40.4 was first expressed after the mid-blastula transition. There was prominent expression in the presomitic paraxial mesoderm and later in the developing somites. In adult frogs, expression was detected in kidney and stomach as well as in brain, heart, and skeletal muscle. Ectopic expression of connexin40.4 in HEK293 cells, resulted in formation of gap junction like structures at the cell interfaces. Similar ectopic expression in neural N2A cells resulted in functional electrical coupling, displaying mild, asymmetric voltage dependence. We thus cloned a novel connexin from Xenopus laevis, strongly expressed in developing somites, with no apparent orthologue in mammals. 相似文献
42.
During hypoxic exercise some vasoconstriction is needed to match O2 delivery with O2 demand at the microcirculatory level. 总被引:1,自引:0,他引:1
Carsten Lundby Robert Boushel Paul Robach Kirsten M?ller Bengt Saltin José A L Calbet 《The Journal of physiology》2008,586(1):123-130
To test the hypothesis that the increased sympathetic tonus elicited by chronic hypoxia is needed to match O(2) delivery with O(2) demand at the microvascular level eight male subjects were investigated at 4559 m altitude during maximal exercise with and without infusion of ATP (80 mug (kg body mass)(-1) min(-1)) into the right femoral artery. Compared to sea level peak leg vascular conductance was reduced by 39% at altitude. However, the infusion of ATP at altitude did not alter femoral vein blood flow (7.6 +/- 1.0 versus 7.9 +/- 1.0 l min(-1)) and femoral arterial oxygen delivery (1.2 +/- 0.2 versus 1.3 +/- 0.2 l min(-1); control and ATP, respectively). Despite the fact that with ATP mean arterial blood pressure decreased (106.9 +/- 14.2 versus 83.3 +/- 16.0 mmHg, P < 0.05), peak cardiac output remained unchanged. Arterial oxygen extraction fraction was reduced from 85.9 +/- 5.3 to 72.0 +/- 10.2% (P < 0.05), and the corresponding venous O(2) content was increased from 25.5 +/- 10.0 to 46.3 +/- 18.5 ml l(-1) (control and ATP, respectively, P < 0.05). With ATP, leg arterial-venous O(2) difference was decreased (P < 0.05) from 139.3 +/- 9.0 to 116.9 +/- 8.4(-1) and leg .VO(2max) was 20% lower compared to the control trial (1.1 +/- 0.2 versus 0.9 +/- 0.1 l min(-1)) (P = 0.069). In summary, at altitude, some degree of vasoconstriction is needed to match O(2) delivery with O(2) demand. Peak cardiac output at altitude is not limited by excessive mean arterial pressure. Exercising leg .VO(2peak) is not limited by restricted vasodilatation in the altitude-acclimatized human. 相似文献
43.
Amy A. Eapen Kirsten M. Kloepfer Frederick E. Leickly James E. Slaven Girish Vitalpur 《Annals of allergy, asthma & immunology》2019,122(2):193-197
Background
Recent studies have suggested that removing foods from the diet to manage atopic dermatitis (AD), based on positive allergy test results, may lead to immediate allergic reactions on reintroduction of that food.Objective
To examine the frequency of oral food challenge (OFC) failures among foods removed from the diet as suspected AD triggers, focusing on the 5 major food allergens in the United States.Methods
OFCs to egg, milk, peanut, soy, and wheat, performed from 2008 to 2014, at a children's hospital's allergy clinics, were reviewed. OFCs were offered based on history and laboratory values. Reasons for food avoidance were classified as food allergy (IgE-mediated reaction occurring within 2 hours); sensitization only (lack of introduction because of positive test results); and removal because of test results during AD evaluation.Results
There were 442 OFCs performed, with 89 failures (20.1%). Reasons for OFCs included a history of food allergy (320 of 442 [72.4%]), food sensitization without any introduction (77 of 442 [17.4%]), and AD (45 of 442 [10.2%]). OFC failures among those who had food allergy (70 of 320 [21.9%]), sensitization only (13 of 77 [16.9%]), and suspected AD trigger (6 of 45 [13.3%]) did not significantly differ (P?=?.63). Wheat was more likely to be avoided than the other 4 foods for AD concerns (P < .001).Conclusion
The frequency of OFC failure among those who removed foods suspected as AD triggers was 13.3%, indicating a loss of tolerance. Restriction of foods to manage AD must be done with caution and close monitoring. 相似文献44.
45.
Philip Eisermann Dennis Rubbenstroth Daniel Cadar Corinna Thom-Bolduan Petra Eggert Alexander Schlaphof Frank Leypoldt Martin Stangel Thorsten Fortwngler Florian Hoffmann Andreas Osterman Sabine Zange Hans-Helmut Niller Klemens Angstwurm Kirsten Prtner Christina Frank Hendrik Wilking Martin Beer Jonas Schmidt-Chanasit Dennis Tappe 《Emerging infectious diseases》2021,27(5):1371
Human bornavirus encephalitis is a severe and often fatal infection caused by variegated squirrel bornavirus 1 (VSBV-1) and Borna disease virus 1 (BoDV-1). We conducted a prospective study of bornavirus etiology of encephalitis cases in Germany during 2018–2020 by using a serologic testing scheme applied along proposed graded case definitions for VSBV-1, BoDV-1, and unspecified bornavirus encephalitis. Of 103 encephalitis cases of unknown etiology, 4 bornavirus infections were detected serologically. One chronic case was caused by VSBV-1 after occupational-related contact of a person with exotic squirrels, and 3 acute cases were caused by BoDV-1 in virus-endemic areas. All 4 case-patients died. Bornavirus etiology could be confirmed by molecular methods. Serologic testing for these cases was virus specific, discriminatory, and a practical diagnostic option for living patients if no brain tissue samples are available. This testing should be guided by clinical and epidemiologic suspicions, such as residence in virus-endemic areas and animal exposure. 相似文献
46.
Josefine Jnsson Kristina M. Renault Sonia García-Calzn Alexander Perfilyev Angela C. Estampador Kirsten Nrgaard Mads Vendelbo Lind Allan Vaag Line Hjort Kim F. Michaelsen Emma Malchau Carlsen Paul W. Franks Charlotte Ling 《Diabetes》2021,70(4):854
Maternal obesity may lead to epigenetic alterations in the offspring and might thereby contribute to disease later in life. We investigated whether a lifestyle intervention in pregnant women with obesity is associated with epigenetic variation in cord blood and body composition in the offspring. Genome-wide DNA methylation was analyzed in cord blood from 208 offspring from the Treatment of Obese Pregnant women (TOP)-study, which includes pregnant women with obesity randomized to lifestyle interventions comprised of physical activity with or without dietary advice versus control subjects (standard of care). DNA methylation was altered at 379 sites, annotated to 370 genes, in cord blood from offspring of mothers following a lifestyle intervention versus control subjects (false discovery rate [FDR] <5%) when using the Houseman reference-free method to correct for cell composition, and three of these sites were significant based on Bonferroni correction. These 370 genes are overrepresented in gene ontology terms, including response to fatty acids and adipose tissue development. Offspring of mothers included in a lifestyle intervention were born with more lean mass compared with control subjects. Methylation at 17 sites, annotated to, for example, DISC1, GBX2, HERC2, and HUWE1, partially mediates the effect of the lifestyle intervention on lean mass in the offspring (FDR <5%). Moreover, 22 methylation sites were associated with offspring BMI z scores during the first 3 years of life (P < 0.05). Overall, lifestyle interventions in pregnant women with obesity are associated with epigenetic changes in offspring, potentially influencing the offspring’s lean mass and early growth. 相似文献
47.
Elaine Ku Charles E. McCulloch Deborah B. Adey Libo Li Kirsten L. Johansen 《Journal of the American Society of Nephrology : JASN》2021,32(3):677
BackgroundPatients may accrue wait time for kidney transplantation when their eGFR is ≤20 ml/min. However, Black patients have faster progression of their kidney disease compared with White patients, which may lead to disparities in accruable time on the kidney transplant waitlist before dialysis initiation.MethodsWe compared differences in accruable wait time and transplant preparation by CKD-EPI estimating equations in Chronic Renal Insufficiency Cohort participants, on the basis of estimates of kidney function by creatinine (eGFRcr), cystatin C (eGFRcys), or both (eGFRcr-cys). We used Weibull accelerated failure time models to determine the association between race (non-Hispanic Black or non-Hispanic White) and time to ESKD from an eGFR of ≤20 ml/min per 1.73 m2. We then estimated how much higher the eGFR threshold for waitlisting would be required to achieve equity in accruable preemptive wait time for the two groups.ResultsBy eGFRcr, 444 CRIC participants were eligible for waitlist registration, but the potential time between eGFR ≤20 ml/min per 1.73 m2 and ESKD was 32% shorter for Blacks versus Whites. By eGFRcys, 435 participants were eligible, and Blacks had 35% shorter potential wait time compared with Whites. By the eGFRcr-cys equation, 461 participants were eligible, and Blacks had a 31% shorter potential wait time than Whites. We estimated that registering Blacks on the waitlist as early as an eGFR of 24–25 ml/min per 1.73 m2 might improve racial equity in accruable wait time before ESKD onset.ConclusionsPolicies allowing for waitlist registration at higher GFR levels for Black patients compared with White patients could theoretically attenuate disparities in accruable wait time and improve racial equity in transplant access. 相似文献
48.
49.
50.
Kirsten Barnicot Jennie Parker Sarah Kalwarowsky Eloise Stevens Jane Iles Paul Ramchandani Mike Crawford 《Psychology and psychotherapy》2023,96(2):480-503