全文获取类型
收费全文 | 5999篇 |
免费 | 419篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 47篇 |
儿科学 | 246篇 |
妇产科学 | 148篇 |
基础医学 | 939篇 |
口腔科学 | 54篇 |
临床医学 | 625篇 |
内科学 | 1152篇 |
皮肤病学 | 62篇 |
神经病学 | 723篇 |
特种医学 | 155篇 |
外科学 | 598篇 |
综合类 | 40篇 |
预防医学 | 662篇 |
眼科学 | 80篇 |
药学 | 471篇 |
中国医学 | 26篇 |
肿瘤学 | 413篇 |
出版年
2024年 | 8篇 |
2023年 | 38篇 |
2022年 | 74篇 |
2021年 | 168篇 |
2020年 | 98篇 |
2019年 | 151篇 |
2018年 | 167篇 |
2017年 | 127篇 |
2016年 | 142篇 |
2015年 | 175篇 |
2014年 | 196篇 |
2013年 | 301篇 |
2012年 | 411篇 |
2011年 | 485篇 |
2010年 | 257篇 |
2009年 | 247篇 |
2008年 | 399篇 |
2007年 | 414篇 |
2006年 | 392篇 |
2005年 | 387篇 |
2004年 | 384篇 |
2003年 | 343篇 |
2002年 | 323篇 |
2001年 | 43篇 |
2000年 | 30篇 |
1999年 | 52篇 |
1998年 | 69篇 |
1997年 | 63篇 |
1996年 | 59篇 |
1995年 | 43篇 |
1994年 | 41篇 |
1993年 | 37篇 |
1992年 | 26篇 |
1991年 | 21篇 |
1990年 | 24篇 |
1989年 | 16篇 |
1988年 | 17篇 |
1987年 | 19篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 22篇 |
1983年 | 16篇 |
1982年 | 17篇 |
1981年 | 14篇 |
1980年 | 20篇 |
1979年 | 11篇 |
1978年 | 12篇 |
1977年 | 5篇 |
1973年 | 5篇 |
1942年 | 4篇 |
排序方式: 共有6441条查询结果,搜索用时 15 毫秒
981.
982.
Joep Perk Guy De Backer Helmut Gohlke Ian Graham ?eljko Reiner W. M. Monique Verschuren Christian Albus Pascale Benlian Gudrun Boysen Renata Cifkova Christi Deaton Shah Ebrahim Miles Fisher Giuseppe Germano Richard Hobbs Arno Hoes Sehnaz Karadeniz Alessandro Mezzani Eva Prescott Lars Ryden Martin Scherer Mikko Syv?nne Wilma J. M. Scholte Op Reimer Christiaan Vrints David Wood Jose Luis Zamorano Faiez Zannad 《International journal of behavioral medicine》2012,19(4):403-488
983.
Hoogendam YY van der Geest JN van der Lijn F van der Lugt A Niessen WJ Krestin GP Hofman A Vernooij MW Breteler MM Ikram MA 《Neurobiology of aging》2012,33(12):2774-2781
In a population-based study of 3962 community-dwelling nondemented elderly we investigated the relation of age, sex, cardiovascular risk factors, and the presence of infarcts with cerebellar volume, and its interrelationship with cerebral volumes. Cerebellar and cerebral gray and white matter were segmented using Freesurfer version 4.5 (http://surfer.nmr.mgh.harvard.edu/). We used linear regression analyses to model the relationship between age, sex, cardiovascular risk factors, brain infarcts, white matter lesions (WMLs) and cerebellar and cerebral volume. Smaller cerebellar volumes with increasing age were mainly driven by loss of white matter. Diabetes, higher serum glucose and lower cholesterol levels were related to smaller cerebellar volume. No association was found between hypertension, smoking, apolipoprotein E (ApoE) genotype, and cerebellar volume. Supratentorial lacunar infarcts and WMLs were related to smaller cerebellar volume. Infratentorial infarcts were related to smaller cerebellar white matter volume and total cerebral volume. This study suggests that determinants of cerebellar volume do not entirely overlap with those established for cerebral volume. Furthermore, presence of infarcts or WMLs in the cerebrum can affect cerebellar volume. 相似文献
984.
Baculoviruses induce apoptotic responses in cultured insect cells, which can severely limit viral replication. To overcome this host response baculoviruses carry anti-apoptotic genes, including members of the p35 and inhibitor of apoptosis (iap) gene families. The baculovirus Helicoverpa armigera nucleopolyhedrovirus (HearNPV) carries two putative apoptosis suppressor genes (iap2 and iap3), which we studied in more detail. IAPs are believed to be functional in the cytoplasm, but surprisingly, when transiently expressed as EGFP fusions, IAP2 was evenly distributed throughout the cell, while IAP3 was mainly found in the nucleus. The latter became evenly distributed in both compartments in HearNPV infected cells. When iap2 was deleted, HearNPV could be propagated in Hz2e5 cells, while an iap3 deletion was lethal. The HearNPV Δiap3 mutant could be rescued by reinsertion of the HearNPV iap3 gene and by the well-studied anti-apoptotic genes Autographa californica (Ac)MNPV p35 or Orgyia pseudotsugata (Op)MNPV iap3. RNAi analysis showed that HearNPV induced apoptosis in Hz2e5 cells transfected with iap3 dsRNA, while silencing of iap2 did not lead to apoptosis. Finally, IAP3 was able to inhibit actinomycin-D induced apoptosis when transiently expressed in Sf21 cells. These results together indicate that HearNPV IAP3 is a functional apoptosis suppressor, while the function of IAP2 remains elusive. 相似文献
985.
Baker LD Asthana S Cholerton BA Wilkinson CW Plymate SR Green PS Merriam GR Fishel MA Watson GS Cherrier MM Kletke ML Mehta PD Craft S 《Neurobiology of aging》2012,33(4):829.e9-829.20
Estradiol has potent favorable effects on brain function and behavior in animals while in human trials, the results are inconsistent. A number of potential mediating variables influencing response to estradiol have been proposed to account for this variability, 1 of which includes stress. We conducted a placebo-controlled study to examine joint and independent effects of estradiol and elevated levels of the stress hormone cortisol on cognition and biomarkers of aging and neurodegenerative disease. Thirty-nine healthy postmenopausal women (56-84 years) received 0.10 mg/dL of transdermal 17β-estradiol (E2) or placebo for 8 weeks. During the last 4 days of the trial, subjects also received 90 mg/day (30 mg 3×/day) of oral hydrocortisone (CORT) to induce stress-level elevations in cortisol, or a matched placebo. The 4 groups thus included placebo (placebo patch/placebo pill), CORT-alone (placebo patch/hydrocortisone), E2-alone (estradiol patch/placebo pill), and E2+CORT (estradiol patch/hydrocortisone). Eight weeks of E2 increased plasma estradiol by 167%, and 4 days of CORT increased plasma cortisol by 119%. Overall, E2 had favorable effects on verbal memory (p = 0.03), working memory (p = 0.02), and selective attention (p = 0.04), and the magnitude of these effects was attenuated for E2+CORT. E2-alone and E2+CORT had opposing effects on plasma levels of the amyloid-β (Aβ) biomarker (Aβ40/42 ratio, p < 0.05), with the more favorable response observed for E2-alone. CORT-induced increases in insulin-like growth factor-1 were blunted by E2 coadministration. Our findings indicate that cognitive and physiological responses to estradiol are adversely affected by elevated stress hormone levels of cortisol in healthy postmenopausal women. 相似文献
986.
987.
988.
Brown KA Timotijevic L Barnett J Shepherd R Lähteenmäki L Raats MM 《The British journal of nutrition》2011,106(1):15-26
Food-based dietary guidelines (FBDG) have primarily been designed for the consumer to encourage healthy, habitual food choices, decrease chronic disease risk and improve public health. However, minimal research has been conducted to evaluate whether FBDG are utilised by the public. The present review used a framework of three concepts, awareness, understanding and use, to summarise consumer evidence related to national FBDG and food guides. Searches of nine electronic databases, reference lists and Internet grey literature elicited 939 articles. Predetermined exclusion criteria selected twenty-eight studies for review. These consisted of qualitative, quantitative and mixed study designs, non-clinical participants, related to official FBDG for the general public, and involved measures of consumer awareness, understanding or use of FBDG. The three concepts of awareness, understanding and use were often discussed interchangeably. Nevertheless, a greater amount of evidence for consumer awareness and understanding was reported than consumer use of FBDG. The twenty-eight studies varied in terms of aim, design and method. Study quality also varied with raw qualitative data, and quantitative method details were often omitted. Thus, the reliability and validity of these review findings may be limited. Further research is required to evaluate the efficacy of FBDG as a public health promotion tool. If the purpose of FBDG is to evoke consumer behaviour change, then the framework of consumer awareness, understanding and use of FBDG may be useful to categorise consumer behaviour studies and complement the dietary survey and health outcome data in the process of FBDG evaluation and revision. 相似文献
989.
Marc I Plourde M Lucas M Sterescu A Piedboeuf B Dufresne A Nuyt AM Lévy E Dodin S 《The Journal of nutrition》2011,141(2):231-236
Very preterm infants are vulnerable to deficiency in DHA. In a longitudinal study, 10 mothers who delivered ≤29 wk gestation and planned to breast-feed received DHA (1200 mg/d) until 36 wk after conception. The plasma DHA status was assessed in their 12 infants (including 2 pairs of twins) from birth to d 49. Fatty acid profiles were measured weekly in breast milk, and in plasma of mothers and infants at baseline and at d15 and 49. Plasma and breast milk fatty acid concentrations in the DHA-supplemented group at d 49 were compared with a reference group of very preterm infants (n = 24, including triplets) whose mothers (n = 22) did not receive DHA during lactation. The infants' plasma DHA concentration tended to be greater in the DHA group than in the reference group (P = 0.10) and was greater when expressed as a percentage of total fatty acids (P = 0.009). At d 49, maternal milk DHA in the DHA group (1.92 ± 1.10 mmol/L) was ~12 times higher than in the reference group (0.15 ± 0.27 mmol/L) (P < 0.001). The amount of DHA provided to the infants increased from wk 1 through wk 7 in the DHA group (P < 0.001). Although enteral intake at wk 7 did not differ between the DHA group [119 ± 51 mL/(kg·d)] and the reference group [113 ± 66 mL/(kg·d)], DHA group infants received 55 ± 38 mg/(kg·d) of DHA, and the reference group infants received 7 ± 11 mg/(kg·d) (P < 0.001). Early supplementation with DHA to lactating mothers with low dietary DHA intake successfully increased the plasma DHA status in very preterm infants. 相似文献
990.
Inactivated polio vaccine development for technology transfer using attenuated Sabin poliovirus strains to shift from Salk-IPV to Sabin-IPV 总被引:1,自引:0,他引:1
Bakker WA Thomassen YE van't Oever AG Westdijk J van Oijen MG Sundermann LC van't Veld P Sleeman E van Nimwegen FW Hamidi A Kersten GF van den Heuvel N Hendriks JT van der Pol LA 《Vaccine》2011,29(41):7188-7196
Industrial-scale inactivated polio vaccine (IPV) production dates back to the 1960s when at the Rijks Instituut voor de Volksgezondheid (RIV) in Bilthoven a process was developed based on micro-carrier technology and primary monkey kidney cells. This technology was freely shared with several pharmaceutical companies and institutes worldwide. In this contribution, the history of one of the first cell-culture based large-scale biological production processes is summarized. Also, recent developments and the anticipated upcoming shift from regular IPV to Sabin-IPV are presented. Responding to a call by the World Health Organization (WHO) for new polio vaccines, the development of Sabin-IPV was continued, after demonstrating proof of principle in the 1990s, at the Netherlands Vaccine Institute (NVI). Development of Sabin-IPV plays an important role in the WHO polio eradication strategy as biocontainment will be critical in the post-OPV cessation period. The use of attenuated Sabin strains instead of wild-type Salk polio strains will provide additional safety during vaccine production. Initially, the Sabin-IPV production process will be based on the scale-down model of the current, and well-established, Salk-IPV process. In parallel to clinical trial material production, process development, optimization and formulation research is being carried out to further optimize the process and reduce cost per dose. Also, results will be shown from large-scale (to prepare for future technology transfer) generation of Master- and Working virus seedlots, and clinical trial material (for phase I studies) production. Finally, the planned technology transfer to vaccine manufacturers in low and middle-income countries is discussed. 相似文献