全文获取类型
收费全文 | 326039篇 |
免费 | 16996篇 |
国内免费 | 990篇 |
专业分类
耳鼻咽喉 | 4768篇 |
儿科学 | 10307篇 |
妇产科学 | 7140篇 |
基础医学 | 44479篇 |
口腔科学 | 8182篇 |
临床医学 | 27906篇 |
内科学 | 63453篇 |
皮肤病学 | 7918篇 |
神经病学 | 29630篇 |
特种医学 | 15326篇 |
外国民族医学 | 38篇 |
外科学 | 52887篇 |
综合类 | 3328篇 |
一般理论 | 144篇 |
预防医学 | 19978篇 |
眼科学 | 7885篇 |
药学 | 21794篇 |
1篇 | |
中国医学 | 647篇 |
肿瘤学 | 18214篇 |
出版年
2023年 | 1600篇 |
2022年 | 1956篇 |
2021年 | 4519篇 |
2020年 | 3137篇 |
2019年 | 4341篇 |
2018年 | 6307篇 |
2017年 | 5074篇 |
2016年 | 6258篇 |
2015年 | 7027篇 |
2014年 | 8701篇 |
2013年 | 12022篇 |
2012年 | 18100篇 |
2011年 | 18265篇 |
2010年 | 10652篇 |
2009年 | 9468篇 |
2008年 | 16992篇 |
2007年 | 18320篇 |
2006年 | 18230篇 |
2005年 | 18680篇 |
2004年 | 17575篇 |
2003年 | 16810篇 |
2002年 | 16418篇 |
2001年 | 8583篇 |
2000年 | 8325篇 |
1999年 | 7677篇 |
1998年 | 3501篇 |
1997年 | 2849篇 |
1996年 | 2309篇 |
1995年 | 2054篇 |
1994年 | 1876篇 |
1993年 | 1697篇 |
1992年 | 3750篇 |
1991年 | 3564篇 |
1990年 | 3387篇 |
1989年 | 3154篇 |
1988年 | 2840篇 |
1987年 | 2777篇 |
1986年 | 2648篇 |
1985年 | 2552篇 |
1984年 | 2245篇 |
1983年 | 1861篇 |
1982年 | 1678篇 |
1981年 | 1514篇 |
1979年 | 2081篇 |
1978年 | 1688篇 |
1977年 | 1414篇 |
1975年 | 1531篇 |
1974年 | 1646篇 |
1973年 | 1489篇 |
1972年 | 1451篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Authors collected from the 82 suppurations of the hip, during the 12 years activity of their Department, the cases treated from some reason conservatively. They had 21 such cases, 17 of them males. The average age of the patients was 38 years and the haematogenous way of the infection could be proven in 15 cases. The scheme of the treatment: very long.lasting giving of broad spectra antibiotics, temporary immobilization with extension, long-lasting relief of weight bearing, if necessary hip spica. The results are assessed critically. In this the tendency of recurrence of the disease, and that the longest follow-up was 10 years, in average however only 3.6 years, play a role. At closing of the material 12 patients stated to be free of complaints, the hip movements were completely retained in 4.9 cases are demonstrated in details and the "strategic" questions of the conservative treatment of the suppurations of the hip are discussed. 相似文献
992.
A W Sedgwick D W Thomas M Davies K Baghurst I Rouse 《Journal of clinical epidemiology》1989,42(3):189-200
Measurements of aerobic fitness, weight, blood pressure, and lipids were made in 1000 sedentary men and women entering a fitness programme, and were repeated 2 years later in 733 subjects. Cross-sectional analyses including (a) comparisons of CHD risk factors in subjects grouped as "low", "low/moderate", "moderate/high", and "high" fitness, and (b) multiple regression analyses of relationships between fitness and risk factors showed that fitter subjects had better risk profiles than less fit. Longitudinal analyses including (a) comparisons of risk factor changes in subjects grouped as fitness "losers", "stable", "small gain", and "large gain", and (b) multiple regression analyses of relationships between fitness change and risk factor changes showed that fitness change was largely unrelated to risk factor changes. The study supported the existence of beneficial associations between fitness and risk factors but not cause and effect relationships. 相似文献
993.
By means of microelectrodes, the activity of single neurons (on-center, off-center ganglion cells, latency class I and class II neurons) was recorded from the optic tract of anesthetized cats. Eyeball deformation in total darkness led fairly consistently to an activation of the on-center ganglion cells, while off-center ganglion cells were inhibited. The latency and strength of this activation or inhibition seemed to be mainly dependent on the strength of eyeball indentation and the location of the neurons relative to the point of eyeball indentation. Some on-center neurons (mostly latency class I) also exhibited a short activation at "deformation off". For comparison, the responses of retinal ganglion cells to eyeball deformation in a hydrostatically open system and to a sudden increase in the intraocular pressure (closed system) are described. The neurophysiological data are explained by the assumption that eyeball indentation leads to a nonuniform tangential stretch of the retina, which exerts a locally variable depolarization of horizontal cells. This horizontal cell depolarization leads either directly or via a feedback loop through cone pedicles to a depolarization of on-bipolars and a hyperpolarization of off-bipolars. These effects determine in turn the responses seen at the ganglion cell level. It is emphasized that eyeball deformation can be used as an independent tool in transmitter studies of the retina. 相似文献
994.
Immunomodulation by cryosurgery in malignant melanoma 总被引:1,自引:0,他引:1
U Weyer I Petersen C Ehrke A Carstensen A Nüssgen C Russ B G?ttsch L Kowalzick R Arndt E W Breitbart 《Onkologie》1989,12(6):291-296
Cryosurgery is a well-known, established method for the local destruction of tumor tissue by freezing. The assumption that, in addition to a physical and blood vascular phase, an immunological phase exists, has been discussed by many authors and tested using animal models. These results can only be transferred to humans in a limited sense. During the last year, we initiated a randomized study "Cryosurgery versus Conventional Surgery", whereby the peripheral blood and the normal skin from the areas surrounding the resection were compared. We were able to demonstrate in the peripheral blood of 8 cryosurgery patients a postoperative increase in the total and helper T-cells, HLA-DR-positive cells, and the ratio helper/suppressor T-cells in comparison to preoperative values. In the 8 patients treated with conventional surgery, these parameters decreased slightly or remained the same. The differences were highly significant (p = 0.001) to significant (p = 0.01). The results from the first 16 are patients studied presented and discussed here. 相似文献
995.
Thomas Lachmann Stefan Berti Teija Kujala Erich Schr?ger 《International journal of psychophysiology》2005,56(2):105-120
The present study addressed auditory processing in 8-11-year-old children with developmental dyslexia by means of event-related brain potentials (ERP). Cortical sound reception was evaluated by recording N250 responses to syllables and tones and cortical sound discrimination by analyzing the mismatch negativity (MMN) to syllable and tone changes. We found that both cortical sound reception and sound discrimination were impaired in dyslexic children. The analysis of the data obtained from two dyslexic subgroups, Dyslexics-1 being impaired in non-word reading (or both non-word and frequent word reading) and Dyslexics-2 in frequent word reading but not in non-word reading, revealed that the MMN was specifically diminished in the latter group whereas it was normal-like in Dyslexics-1. However, no differences were found between these subgroups in sound reception as indicated by the responses elicited by the standard stimuli. These results show that different diagnostic subgroups of dyslexics have different patterns of auditory processing deficits as suggested by similarly impaired sound reception in both dyslexic groups and the sound-discrimination impairment specific to one of the groups. 相似文献
996.
Human infection with Histoplasma capsulatum or Blastomyces dermatitidis is sufficiently frequent to warrant exploring the development of vaccines. This review examines the advancements that have been accomplished over the last few years. The availability of molecular tools to create recombinant antigens or mutant strains has produced a small number of useful vaccine candidates. More importantly, the studies summarized herein demonstrate that understanding the host response to a protein or mutant fungus is critical to creating a vaccine that may be useful for the immunocompromised patient. 相似文献
997.
Functional analysis of the cag pathogenicity island in Helicobacter pylori isolates from patients with gastritis, peptic ulcer, and gastric cancer 总被引:9,自引:0,他引:9 下载免费PDF全文
Backert S Schwarz T Miehlke S Kirsch C Sommer C Kwok T Gerhard M Goebel UB Lehn N Koenig W Meyer TF 《Infection and immunity》2004,72(2):1043-1056
Helicobacter pylori is the causative agent of a variety of gastric diseases, but the clinical relevance of bacterial virulence factors is still controversial. Virulent strains carrying the cag pathogenicity island (cagPAI) are thought to be key players in disease development. Here, we have compared cagPAI-dependent in vitro responses in H. pylori isolates obtained from 75 patients with gastritis, peptic ulcer, and gastric cancer (n = 25 in each group). AGS gastric epithelial cells were infected with each strain and assayed for (i) CagA expression, (ii) translocation and tyrosine phosphorylation of CagA, (iii) c-Src inactivation, (iv) cortactin dephosphorylation, (v) induction of actin cytoskeletal rearrangements associated with cell elongation, (vi) induction of cellular motility, and (vii) secretion of interleukin-8. Interestingly, we found high but similar prevalences of all of these cagPAI-dependent host cell responses (ranging from 56 to 80%) among the various groups of patients. This study revealed CagA proteins with unique features, CagA subspecies of various sizes, and new functional properties for the phenotypic outcomes. We further showed that induction of AGS cell motility and elongation are two independent processes. Our data corroborate epidemiological studies, which indicate a significant association of cagPAI presence and functionality with histopathological findings in gastritis, peptic ulcer, and gastric cancer patients, thus emphasizing the importance of the cagPAI for the pathogenicity of H. pylori. Nevertheless, we found no significant association of the specific H. pylori-induced responses with any particular patient group. This may indicate that the determination of disease development is highly complex and involves multiple bacterial and/or host factors. 相似文献
998.
Füst G Arason GJ Kramer J Szalai C Duba J Yang Y Chung EK Zhou B Blanchong CA Lokki ML Bödvarsson S Prohászka Z Karádi I Vatay A Kovács M Romics L Thorgeirsson G Yu CY 《International immunology》2004,16(10):1507-1514
The genetic basis for addiction to tobacco smoking--particularly that of the perception of olfactory stimuli that may be important in reinforcing smoking addiction--is largely unknown. A cluster of genes for olfactory receptors is in close proximity to the MHC region on chromosome 6. Polymorphisms of MHC class III genes (RCCX modules, TNFA promoter polymorphisms) were determined in 101 healthy subjects and 232 coronary artery disease (CAD) patients from Hungary with defined tobacco smoking habits. A highly significant association between ever smoking (past + current smokers) and a specific MHC haplotype was observed (odds ratios = 2.14-4.13; P-values = 0.012 to <0.001). This haplotype is characterized by the presence of C4A null alleles and a solitary short C4B gene linked to the TNF2 allele of the promoter for TNFA gene. This haplotype occurred more frequently in the ever smokers than in the never smokers [odds ratio: 4.97 (1.96-12.62); P = 0.001], and such associations were stronger in women (odds ratio = 13.6) than in men (odds ratio = 2.79). An independent study of complement C4 protein polymorphism and smoking habits in Icelandic subjects (n = 351) yielded similar and confirmative results. Considering the documented link between olfactory stimuli and smoking in females, and the presence of a cluster of odorant receptor genes close to the MHC class I region, our findings implicate a potential role of the MHC-linked olfactory receptor genes in the initiation of smoking. 相似文献
999.
Effect of moderate exercise on salivary immunoglobulin A and infection risk in humans 总被引:3,自引:0,他引:3
Klentrou P Cieslak T MacNeil M Vintinner A Plyley M 《European journal of applied physiology》2002,87(2):153-158
The incidence of upper respiratory tract infections (URTI) and salivary immunoglobulin A concentrations [IgAs] of nine individuals were examined during 12 weeks of moderate exercise training, and compared to ten sedentary controls.
Changes in maximal oxygen uptake were assessed at initial, mid-point and final evaluations (T1–3), while changes in [IgAs] and salivary immunoglobulin concentration-salivary albumin concentration ratio ([IgAs]:[Albs]) were monitored at T1 and T3. During the 12 week period, symptoms of URTI were self-recorded daily. During the period of
training the level of fitness significantly increased (P<0.05) in the exercise group. The number of days recording symptoms of influenza, but not of cold, and total light URTI symptoms was significantly reduced in the exercise group during the last weeks of training. A significant increase in
[IgAs] and in [IgAs]:[Albs] was found in the exercise group after training. Both [IgAs] and [IgAs]:[Albs] were significantly related to the number of days showing symptoms of influenza (P<0.01) and the total number of days of sickness (P<0.05). These data provide quantitative support for the belief that regular, moderate exercise results in an increased [IgAs] at rest and [IgAs]:[Albs], which may contribute to a decreased risk of infection.
Electronic Publication 相似文献
1000.
Cholinergic influences on use-dependent plasticity. 总被引:7,自引:0,他引:7
L Sawaki B Boroojerdi A Kaelin-Lang A H Burstein C M Bütefisch L Kopylev B Davis L G Cohen 《Journal of neurophysiology》2002,87(1):166-171
Motor practice elicits use-dependent plasticity in humans as well as in animals. Given the influence of cholinergic neurotransmission on learning and memory processes, we evaluated the effects of scopolamine (a muscarinic receptor antagonist) on use-dependent plasticity and corticomotor excitability in a double-blind placebo-controlled randomized design study. Use-dependent plasticity was substantially attenuated by scopolamine in the absence of global changes in corticomotor excitability. These results identify a facilitatory role for cholinergic influences in use-dependent plasticity in the human motor system. 相似文献