全文获取类型
收费全文 | 2769篇 |
免费 | 126篇 |
国内免费 | 88篇 |
专业分类
耳鼻咽喉 | 29篇 |
儿科学 | 85篇 |
妇产科学 | 35篇 |
基础医学 | 371篇 |
口腔科学 | 82篇 |
临床医学 | 307篇 |
内科学 | 591篇 |
皮肤病学 | 85篇 |
神经病学 | 321篇 |
特种医学 | 98篇 |
外科学 | 445篇 |
综合类 | 46篇 |
预防医学 | 120篇 |
眼科学 | 22篇 |
药学 | 156篇 |
中国医学 | 3篇 |
肿瘤学 | 187篇 |
出版年
2021年 | 20篇 |
2020年 | 31篇 |
2019年 | 29篇 |
2018年 | 31篇 |
2017年 | 43篇 |
2016年 | 38篇 |
2015年 | 42篇 |
2014年 | 60篇 |
2013年 | 93篇 |
2012年 | 70篇 |
2011年 | 91篇 |
2010年 | 64篇 |
2009年 | 64篇 |
2008年 | 84篇 |
2007年 | 146篇 |
2006年 | 89篇 |
2005年 | 106篇 |
2004年 | 95篇 |
2003年 | 86篇 |
2002年 | 85篇 |
2001年 | 71篇 |
2000年 | 90篇 |
1999年 | 99篇 |
1998年 | 79篇 |
1997年 | 48篇 |
1996年 | 66篇 |
1995年 | 35篇 |
1994年 | 47篇 |
1993年 | 35篇 |
1992年 | 73篇 |
1991年 | 66篇 |
1990年 | 66篇 |
1989年 | 69篇 |
1988年 | 84篇 |
1987年 | 75篇 |
1986年 | 66篇 |
1985年 | 46篇 |
1984年 | 52篇 |
1983年 | 47篇 |
1982年 | 30篇 |
1981年 | 31篇 |
1980年 | 27篇 |
1979年 | 30篇 |
1978年 | 35篇 |
1977年 | 29篇 |
1976年 | 26篇 |
1975年 | 26篇 |
1974年 | 23篇 |
1973年 | 23篇 |
1971年 | 23篇 |
排序方式: 共有2983条查询结果,搜索用时 15 毫秒
71.
72.
Organizational wisdom 总被引:1,自引:0,他引:1
In recent years, much theoretical and empirical attention has focused on wisdom as a psychological construct. The development of wisdom is viewed as a positive aspect of aging, but also has a complement to more traditionally-studied domains of intelligence. Two studies, involving a total of 327 adults, examined how our understanding of the construct might be furthered by its application into specific, problematic contexts, and by having its utility assessed. This involved: 1) development of an instrument that related the elements of wisdom to the context of work organizations; 2) identification of the primary ways in which wisdom contributes to well-being in work organizations; and 3) identification of types of organizations (organizational cultures) most likely to need and value wise persons of influence in their midst. Results suggest that wisdom is of greatest consequence when it fills an important gap in what is offered by the organization's (or society's) formal structure. Where the culture has developed more formal institutions, structure, and principles to guide its activities and ensure fairness in how people are treated, there may be less need for informal sources of organizational wisdom. 相似文献
73.
Sjöström S Sillén U Bachelard M Hansson S Stokland E 《The Journal of urology》2004,172(2):694-8; discussion 699
PURPOSE: We studied the spontaneous resolution rate in a group of infants with high grade vesicoureteral reflux (VUR). The influence of gender, prenatal or postnatal diagnosis, recurrent urinary tract infections (UTIs) and bladder dysfunction on the resolution rate was also evaluated. MATERIALS AND METHODS: This prospective study comprised 115 infants (80 boys and 35 girls) with high grade VUR (grades III to V). Bilateral reflux was seen in 70% of cases. The majority of patients (71%) were diagnosed after UTI during infancy and only 26% were prenatally diagnosed. Median age at diagnosis was 2.7 months. Patients were followed according to a program of repeat video cystometry and noninvasive 4-hour voiding observations. Median followup was 39 months. RESULTS: The overall spontaneous resolution rate to grade II or less for all grades was 39% with no difference between boys and girls. However, when comparing the more severe grades IV and V, we found a significantly higher resolution rate in boys during the infant year. No difference in VUR disappearance could be detected when comparing the groups according to presentation, prenatal ultrasound or pyelonephritis. Breakthrough UTIs were seen in 47% of cases despite antibacterial prophylaxis and they significantly correlated with VUR nonresolution. Bladder dysfunction was found in 37% of patients and it also significantly correlated with nonresolution. CONCLUSIONS: The spontaneous resolution rate for high grade (grades IV and V) congenital VUR was high in boys during the infant year (29%), whereas in girls and boys after the infant year the resolution rate was 9% yearly during followup. Negative prognostic factors for resolution were recurrent UTIs and bladder dysfunction. 相似文献
74.
This account describes novel mushroom body organization in a coleopteran insect, the African fruit chafer Pachnoda marginata. Each of its prominent mushroom bodies possesses a pair of simple calyces comprising two populations of Kenyon cells, the dendrites of which are organized into a central and an annular zone. Kenyon cells of the central zone extend their dendrites downward and toward the perimeter of the calyx. Their axon-like processes in the pedunculus are densely packed to make up a distinctive shaft of neuropil. Toward the front of the brain, the shafts, one from each calyx, bifurcate to provide a pair of subdivisions in the medial and vertical lobes. Dendrites of Kenyon cells supplying the annular zone extend from the calyx perimeter toward its center. Axons from the annular zones of both calyces together provide a sleeve of axons that ensheaths the two shafts. Sleeve axons bifurcate to provide a second pair of divisions in each of the lobes. These arrangements provide each lobe with a discrete representation of the two Kenyon cell populations of the two calyces. Kenyon cells supplying the central zone have dendritic morphologies reminiscent of class II clawed Kenyon cells that supply the gamma lobes in other taxa. Kenyon cells supplying axons to the sleeve are suggestive of class III Kenyon cell morphologies described from cockroaches and termites. Elaborate intrinsic neurons, comparable to exotic intrinsic neurons in the honey bee gamma lobes, have processes that interact with shaft axons. The present observations suggest that mushroom bodies of Pachnoda represent either a basal organization entirely lacking class I Kenyon cells or an evolutionary modification in which there is no clear morphological distinction of class I and II Kenyon cells. In either case, cellular organization in Pachnoda's mushroom body is simple compared with that of other taxa. 相似文献
75.
A majority of cutaneous melanomas show activating mutations in the NRAS or BRAF proto-oncogenes, components of the Ras-Raf-Mek-Erk signal transduction pathway. Consistent data demonstrate the early appearance, in a mutually exclusive manner, of these mutations. The purpose of this paper is to summarize the literature on NRAS and BRAF activating mutations in melanoma tumors with respect to available data on histogenetic classification as well as body site and presumed UV-exposure. Common alterations of the signal transducing network seem to represent molecular hallmarks of cutaneous melanomas and therefore should continue to strongly stimulate design and testing of targeted molecular interventions. 相似文献
76.
77.
Mosquitoes are heavily dependent on gustatory information when feeding. Following the recent elucidation of the molecular basis of gustation in the malaria mosquito, we present a detailed study of primary central projections of gustatory receptor neurons into the brain in the malaria (Anopheles gambiae) and yellow fever (Aedes aegypti) mosquito. In the brain we provide a detailed map of the areas targeted and describe a number of intrinsic neural elements connecting primary taste areas to higher brain levels. The morphological features described are discussed and compared to earlier reports in other insects as, e.g., the fruitfly, Drosophila. 相似文献
78.
A rotational acceleration impulse to a head, as occurs at traffic accidents, sport injuries, assaults and falls, induces a diffuse brain damage that eventually could result in persistent neuropsychiatric deficits and neurodegeneration. Emphasis has been concentrated on the relative motion of the brain inside the skull during head impact, whereas less attention has been paid to whether intracranial pressure changes are generated and, if so, the implications thereof. In the present experimental study we investigated in an animal model system, based on rabbits, if a sagittal, anterior-posterior rotational acceleration of a head generated intracranial pressure changes, recorded by fibre optic pressure sensors, inserted ipsilaterally in the parieto-temporal and the occipital lobes. Two levels of rotational acceleration were used in the experiments; one higher, corresponding to the threshold limit for moderate diffuse brain injury, and one lower, close to being noninjurious. Several pressure recordings were performed in each rabbit at the two acceleration levels. The pressure recordings invariably revealed the same general characteristics of rapid, positive and negative pressures within the brain, with variations in amplitude and duration, lasting for up to 10 ms. A major finding was the generation of powerful negative pressures, as low as 0.3 bars in absolute pressure. The most prominent difference in amplitudes of the negative peak pressures between the two applied acceleration levels was demonstrated at the parieto-temporal location. The presented pressure recordings are the first to disclose the generation of transient, powerful intracerebral pressures at rotational acceleration of the head, which must be considered in studies of brain injury generation and distribution as well as prevention. 相似文献
79.
Magnusson PKE Enroth H Eriksson I Held M Nyrén O Engstrand L Hansson LE Gyllensten UB 《Cancer research》2001,61(6):2684-2689
DNA and sera from 130 cases of gastric cancer and 263 population-based controls were analyzed to study the association of HLA class II DR-DQ alleles with Helicobacter pylori (Hp) infection and the risk for gastric cancer. Presence of the DQA1*0102 allele was inversely and significantly associated with Hp seropositivity (P = 2 x 10(-5)), which is an independent replication of previous findings. However, this inverse relationship with Hp did not correspond with a reduced risk of gastric cancer. At the DRB1 locus, the *1601 allele was significantly associated with an increased gastric cancer risk with an odds ratio (95% confidence interval) of 8.7 (range, 2.7-28.0). The effect of *1601 was more pronounced among Hp-negative subjects, and the association was stronger with the diffuse, rather than with the intestinal, histological type of gastric cancer. Because none of the HLA alleles were associated with both Hp infection and gastric cancer, the HLA DR-DQ alleles are linked with gastric cancer risk through other mechanisms than an increased susceptibility to Hp infection. 相似文献
80.
Marianne Cederblad Lisa Dahlin Olle Hagnell Kjell Hansson 《European archives of psychiatry and clinical neuroscience》1995,245(1):11-19
The Sjöbring system of personality dimensions measuring intellectual capacity, activity, impulsivity and sociability was used to study possible salutogenic (i.e. causes of health) effects. The study comprised 590 subjects investigated in 1947, 1957, 1972 and 1988–1989 in the Lundby project, an epidemiological study in Sweden. Psychiatric diagnoses were made in 1947, 1957 and 1972. Mental health was estimated in 1988–1989 using the concept love well, work well, play well and expect well. The Sjöbring dimensions were clinically assessed in 1972. Both in the concurrent study in 1972 and in the prospective study in 1988–1989 super capacity (high intellectual function), super validity (high activity level) and super solidity (low impulsivity) were statistically associated with lower frequencies of certain psychiatric diagnoses and a higher frequency of positive mental health. These variables are proposed to increase coping capacity, and therefore increase stress resilience. 相似文献