全文获取类型
收费全文 | 827篇 |
免费 | 75篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 18篇 |
妇产科学 | 13篇 |
基础医学 | 138篇 |
口腔科学 | 5篇 |
临床医学 | 106篇 |
内科学 | 154篇 |
皮肤病学 | 11篇 |
神经病学 | 95篇 |
特种医学 | 23篇 |
外科学 | 82篇 |
综合类 | 2篇 |
预防医学 | 95篇 |
眼科学 | 4篇 |
药学 | 86篇 |
肿瘤学 | 62篇 |
出版年
2024年 | 5篇 |
2023年 | 17篇 |
2022年 | 21篇 |
2021年 | 39篇 |
2020年 | 26篇 |
2019年 | 41篇 |
2018年 | 35篇 |
2017年 | 36篇 |
2016年 | 36篇 |
2015年 | 35篇 |
2014年 | 36篇 |
2013年 | 47篇 |
2012年 | 87篇 |
2011年 | 72篇 |
2010年 | 29篇 |
2009年 | 35篇 |
2008年 | 50篇 |
2007年 | 46篇 |
2006年 | 45篇 |
2005年 | 44篇 |
2004年 | 35篇 |
2003年 | 29篇 |
2002年 | 21篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有903条查询结果,搜索用时 296 毫秒
1.
Arvid Nikolai Kildahl Sissel Berge Helverschou Trine Lise Bakken Hanne Weie Oddli 《Journal of mental health research in intellectual disabilities》2020,13(3):201-230
ABSTRACT
Introduction
Individuals with autism spectrum disorder (ASD) and intellectual disability (ID) seem to be at increased risk for post-traumatic stress disorder (PTSD), but knowledge is sparse regarding its identification in this population. Previous research indicates that certain symptoms of PTSD may be more easily recognized, and that identifying reexperiencing and avoidance is particularly challenging. 相似文献2.
Trine Juhler N?ttrup Stine Sofia Korreman Anders Navrsted Pedersen Lasse Rye Aarup H?kan Nystr?m Mikael Olsen Lena Specht 《Radiotherapy and oncology》2007,84(1):40-48
BACKGROUND AND PURPOSE: This study aimed at quantifying the breathing variations among lung cancer patients over full courses of fractionated radiotherapy. The intention was to relate these variations to the margins assigned to lung tumours, to account for respiratory motion, in fractionated radiotherapy. MATERIALS AND METHODS: Eleven lung cancer patients were included in the study. The patients' chest wall motions were monitored as a surrogate measure for breathing motion during each fraction of radiotherapy by use of an external optical marker. The exhale level variations were evaluated with respect to exhale points and fraction-baseline, defined for intra- and interfraction variations respectively. The breathing amplitude was evaluated as breathing cycle amplitudes and fraction-max-amplitudes defined for intra- and interfraction breathing, respectively. RESULTS: The breathing variations over a full treatment course, including both intra- and interfraction variations, were 15.2mm (median over the patient population), range 5.5-26.7mm, with the variations in exhale level as the major contributing factor. The median interfraction span in exhale level was 14.8mm, whereas the median fraction-max-amplitude was 6.1mm (median of patient individual SD 1.4). The median intrafraction span in exhale level was 1.6mm, and the median breathing cycle amplitude was 4.0mm (median of patient individual SD 1.4). CONCLUSIONS: The variations in externally measured exhale levels are larger than variations in breathing amplitude. The interfraction variations in exhale level are in general are up to 10 times larger than intrafraction variations. Margins to account for respiratory motion cannot safely be based on one planning session, especially not if relying on measuring external marker motion. Margins for lung tumours should include interfraction variations in breathing. 相似文献
3.
Geographical and temporal conservation of antibody recognition of Plasmodium falciparum variant surface antigens
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nielsen MA Vestergaard LS Lusingu J Kurtzhals JA Giha HA Grevstad B Goka BQ Lemnge MM Jensen JB Akanmori BD Theander TG Staalsoe T Hviid L 《Infection and immunity》2004,72(6):3531-3535
The slow acquisition of protection against Plasmodium falciparum malaria probably reflects the extensive diversity of important antigens. The variant surface antigens (VSA) that mediate parasite adhesion to a range of host molecules are regarded as important targets of acquired protective immunity, but their diversity makes them questionable vaccine candidates. We determined levels of VSA-specific immunoglobulin G (IgG) in human plasma collected at four geographically distant and epidemiologically distinct localities with specificity for VSA expressed by P. falciparum isolates from three African countries. Plasma levels of VSA-specific IgG recognizing individual parasite isolates depended on the transmission intensity at the site of plasma collection but were largely independent of the geographical origin of the parasites. The total repertoire of immunologically distinct VSA thus appears to be finite and geographically conserved, most likely due to functional constraints. Furthermore, plasma samples frequently had high IgG reactivity to VSA expressed by parasites isolated more than 10 years later, showing that the repertoire is also temporally stable. Parasites from patients with severe malaria expressed VSA (VSASM) that were better recognized by plasma IgG than VSA expressed by other parasites, but importantly, VSASM-type antigens also appeared to show substantial antigenic homogeneity. Our finding that the repertoire of immunologically distinct VSA in general, and in particular that of VSASM, is geographically and temporally conserved raises hopes for the feasibility of developing VSA-based vaccines specifically designed to accelerate naturally acquired immunity, thereby enhancing protection against severe and life-threatening P. falciparum malaria. 相似文献
4.
Intermittent preventive sulfadoxine-pyrimethamine treatment of primigravidae reduces levels of plasma immunoglobulin G, which protects against pregnancy-associated Plasmodium falciparum malaria
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Staalsoe T Shulman CE Dorman EK Kawuondo K Marsh K Hviid L 《Infection and immunity》2004,72(9):5027-5030
Pregnancy-associated malaria (PAM) is an important cause of maternal and neonatal suffering. It is caused by Plasmodium falciparum capable of inhabiting the placenta through expression of particular variant surface antigens (VSA) with affinity for proteoglycans such as chondroitin sulfate A. Protective immunity to PAM develops following exposure to parasites inhabiting the placenta, and primigravidae are therefore particularly susceptible to PAM. The adverse consequences of PAM in primigravidae are preventable by intermittent preventive treatment (IPTp), where women are given antimalarials at specified intervals during pregnancy, but this may interfere with acquisition of protective PAM immunity. We found that Kenyan primigravidae receiving sulfadoxine-pyrimethamine IPTp had significantly lower levels of immunoglobulin G (IgG) with specificity for the type of parasite-encoded VSA-called VSA(PAM)-that specifically mediate protection against PAM than did women receiving a placebo. VSA(PAM)-specific IgG levels depended on the number of IPTp doses received and were sufficiently low to be of clinical concern among multidose recipients. Our data suggest that IPTp should be extended to women of all parities, in line with current World Health Organization recommendations. 相似文献
5.
The hormonal responses of nine male, strength athletes to strength exercise were examined. The athletes performed one moderate-
and one high-intensity strength exercise workout. In the high-intensity workout, the load was 100% of each subject's three-repetition
maximum (3-RM) for squats and front squats, and 100% of each subject's six-repetition maximum (6-RM) for leg extensions. In
the moderate-intensity workout, the load was 70% of the high-intensity protocol. Rest periods between sets were 4–6 min for
both workouts. Blood samples were taken before, 30 min into, and every 15 min for the 1st h after exercise, and then 3, 7,
11, 22 and 33 h after exercise, thus allowing examination of both the acute and prolonged hormonal responses. Blood samples
were analyzed for testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH), cortisol, adrenocorticotrophic
hormone (ACTH), growth hormone (GH), insulin-like growth factor (IGF-1), insulin, sex hormone binding globulin, creatine kinase,
total protein, glucose and lactate. The acute responses of testosterone and cortisol were greater during the high-intensity
protocol as compared to the moderate-intensity protocol. The cortisol response was associated with an increase in ACTH concentration.
LH and FSH showed no response to either protocol. Acute GH responses were not different between protocols. There were great
inter-individual differences in acute GH responses to both protocols. There were no significant differences between protocols
with regard to prolonged responses for any hormone. In both trials, IGF-1 concentrations were significantly lower at 0800 hours
the morning after exercise as compared to concentrations found at 0800 hours the morning before exercise. The mechanisms responsible
for reducing IGF-1 concentration in these trials are unclear, and it is not known if this reduction observed 22 hours after
exercise is of physiological significance.
Accepted: 13 December 1999 相似文献
6.
Bergmo TS Kummervold PE Gammon D Dahl LB 《International journal of medical informatics》2005,74(9):705-710
BACKGROUND AND AIM: Electronic patient-provider communication promises to improve efficiency and effectiveness of clinical care. This study aims to explore whether a secure web-based messaging system is an effective way of providing patient care in general practices. METHOD: We conducted a randomised controlled trail and recruited 200 patients from the waiting area in one primary clinic in Norway. Participants were randomised to either the intervention group, which received access to a secure messaging system, or the control group receiving standard care without such access. Primary outcome measures were number of online consultations, telephone consultations and office visits in the two groups. Data were derived from patient records and collected 1 year prior to (baseline), and 1 year after the intervention. RESULTS: Forty-six percent of the patients who were given access to the messaging system (n=99) used the online communication system on at least one occasion (ranging from 1 to 17 messages per patient per year). A total of 147 electronic messages were sent to six general practitioners during a 1-year trial period. Eleven percent of the messages were to schedule an appointment. In 10% of the messages, the GP was unable to respond adequately and recommended an office visit. The reduction in office visits over time was greater for the intervention group than for the control group (P=0.034). There was however no significant difference in the number of telephone consultations between the groups during the study (P=0.258). CONCLUSION: The use of a secure electronic messaging system reduced the number of office visits at the general practice, but not phone consultations. 相似文献
7.
Functional coupling between heterologously expressed dopamine D(2) receptors and KCNQ channels 总被引:1,自引:0,他引:1
Ljungstrom T Grunnet M Jensen BS Olesen SP 《Pflügers Archiv : European journal of physiology》2003,446(6):684-694
Activation of KCNQ potassium channels by stimulation of co-expressed dopamine D2 receptors was studied electrophysiologically in Xenopus laevis oocytes and in mammalian cells. To address the specificity of the interaction between D2-like receptors and KCNQ channels, combinations of KCNQ1–5 channels and D2-like receptors (D2L, D3, and D4) were investigated in Xenopus oocytes. Activation of either receptor with the selective D2-like receptor agonist quinpirole (100 nM) stimulated all the KCNQ currents, independently of the subunit combination, indicating a common pathway of receptor-channel interaction. The KCNQ4 current was investigated in further detail and was increased by 19.9±1.6% (n=20) by D2L receptor stimulation. The effect could be mimicked by injection of GTPS and prevented by injection of Bordetella pertussis toxin, indicating that channel stimulation was mediated via a G protein of the Gi/o subtype. Cells of the human neuroblastoma line SH-SY5Y were co-transfected transiently with KCNQ4 and D2L receptors. Stimulation of D2L receptors increased the KCNQ4 current (n=6) as determined in whole-cell patch-clamp recordings. The specificity of the dopaminergic activation of the KCNQ channels was confirmed by co-expression of other neuronal K+ channels (BK, KV1.1, and KV4.3) with the D2L receptor in Xenopus oocytes. None of these K+ channels responded to stimulation of the D2L receptor. In the mammalian brain, dopamine D2 receptors and KCNQ channels co-localise postsynaptically in several brain regions, so modulation of neuronal excitability by dopamine release could in part be mediated via an effect on KCNQ channels. 相似文献
8.
A practice analysis, in which an appropriate sample of professionals is asked to describe what they do in their practices, is considered an essential part of the content-related validity evidence for licensure and certification tests. This article examines the precision of estimates of the mean frequencies for categories of activities in an activity inventory administered on two occasions about 6 weeks apart. In particular, it explores the variability in estimates of the mean frequencies for categories due to the sampling of respondents, activity statements, and occasions. The results suggest that samples of 200 respondents, about 10 to 20 activity statements per category, and one occasion are adequate for estimating the mean frequency for each category. 相似文献
9.
Polybrominated diphenyl ethers (PBDEs) are widely used brominated flame retardants (BFRs), which have become ubiquitous in the environment. This study investigates the effects of the pentabrominated diphenyl ether mixture, DE-71, on human neutrophil granulocytes in vitro. DE-71 enhanced production of reactive oxygen species (ROS) in a concentration-dependent manner measured as lucigenin-amplified chemiluminescence. Octabrominated diphenyl ether (OBDE), decabrominated diphenyl ether (DBDE), and the non-brominated diphenyl ether did not induce ROS formation at the concentrations tested. DPI (4 microM), an inhibitor of the NADPH oxidase completely inhibited DE-71 induced ROS formation, highlighting a role for NADPH oxidase activation. The protein kinase C inhibitor BIM (0.25 microM) and the selective chelator of intracellular calcium, BAPTA-AM (5 microM), also inhibited NADPH oxidase activation, indicating a calcium-dependent activation of PKC. ROS formation was also inhibited by the tyrosine kinase inhibitor tyrphostin (1 microM), the phospholipase C inhibitor ET-18-OCH3 (5 microM), and the phosphatidylinositol-3 kinase inhibitor LY294002 (25 microM). Alterations in intracellular calcium were measured using fura-2/AM, and a significant increase was measured after exposure to DE-71 both with and without extracellular calcium. The tetra brominated compound BDE-47 also enhanced ROS formation in a concentration dependent manner. The combination of DE-71 with the bacteria-derived N-formyl peptide fMLP and PCB153 induced an additive effect in the lucigenin assay. We suggest that tyrosine kinase mediated activation of PI3K could result in enhanced activation of calcium-dependent PKC by enhanced PLC activity, followed by intracellular calcium release leading to ROS formation in neutrophil granulocytes. 相似文献
10.
Trine R. Hopp Ellen W. Srensen Hanne Herborg Alison S. Roberts 《The International journal of pharmacy practice》2005,13(1):21-31
Objective To investigate the implementation process of cognitive pharmaceutical services (CPS) in ‘professionally active’ pharmacies in Denmark; to describe the factors that influence the implementation process in the context of organisational theory. Method Twenty semi‐structured interviews were conducted with pharmacy staff and owners in ‘professionally active’ pharmacies from 16 community pharmacies in Denmark. Key findings Fifty‐one factors that influence the implementation process were identified. Based on their content and relationships, the factors were categorised into nine ‘common sense’ dimensions: network and relations with the environment; the environment's expectations and pressure for change; barriers to implementation of CPS; competence in relation to CPS; organising the pharmacy for provision of CPS; culture of the pharmacy; resources within the pharmacy; management within the pharmacy; the role of the pharmacy. Subsequently the 51 factors were categorised and described in relation to Leavitt's model of an organisation. Conclusion Implementation of CPS in the pharmacy is a very complex process, which is unique to the individual pharmacy. The model formed a relevant basis for describing the factors, and the theoretical analysis showed a complex interdependence of the factors identified in the study. Many interdependent factors influence the process and this has to be taken into account in designing future models for implementation of CPS. Such models should support comprehensive and flexible strategies that can be adapted to the dynamics of the individual organisation. 相似文献