全文获取类型
收费全文 | 51122篇 |
免费 | 5401篇 |
国内免费 | 679篇 |
专业分类
耳鼻咽喉 | 462篇 |
儿科学 | 2193篇 |
妇产科学 | 1016篇 |
基础医学 | 6238篇 |
口腔科学 | 1493篇 |
临床医学 | 9041篇 |
内科学 | 4686篇 |
皮肤病学 | 311篇 |
神经病学 | 5531篇 |
特种医学 | 889篇 |
外国民族医学 | 4篇 |
外科学 | 3627篇 |
综合类 | 4890篇 |
现状与发展 | 6篇 |
一般理论 | 12篇 |
预防医学 | 9330篇 |
眼科学 | 594篇 |
药学 | 3761篇 |
47篇 | |
中国医学 | 1408篇 |
肿瘤学 | 1663篇 |
出版年
2024年 | 310篇 |
2023年 | 1133篇 |
2022年 | 1457篇 |
2021年 | 2215篇 |
2020年 | 2420篇 |
2019年 | 2403篇 |
2018年 | 2141篇 |
2017年 | 2186篇 |
2016年 | 2053篇 |
2015年 | 2092篇 |
2014年 | 3061篇 |
2013年 | 3983篇 |
2012年 | 2742篇 |
2011年 | 2889篇 |
2010年 | 2585篇 |
2009年 | 2503篇 |
2008年 | 2405篇 |
2007年 | 2389篇 |
2006年 | 2044篇 |
2005年 | 1808篇 |
2004年 | 1525篇 |
2003年 | 1320篇 |
2002年 | 1094篇 |
2001年 | 935篇 |
2000年 | 825篇 |
1999年 | 750篇 |
1998年 | 694篇 |
1997年 | 562篇 |
1996年 | 513篇 |
1995年 | 479篇 |
1994年 | 425篇 |
1993年 | 360篇 |
1992年 | 326篇 |
1991年 | 268篇 |
1990年 | 265篇 |
1989年 | 197篇 |
1988年 | 193篇 |
1987年 | 170篇 |
1986年 | 187篇 |
1985年 | 221篇 |
1984年 | 209篇 |
1983年 | 124篇 |
1982年 | 112篇 |
1981年 | 136篇 |
1980年 | 126篇 |
1979年 | 78篇 |
1978年 | 76篇 |
1977年 | 40篇 |
1976年 | 47篇 |
1974年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Bonnie J. Baty Lynn B. Jorde Brent L. Blackburn John C. Carey 《American journal of medical genetics. Part A》1994,49(2):189-194
Developmental data were abstracted from medical records on 50 trisomy 18 individuals ranging in age from 1 to 232 months and 12 trisomy 13 individuals ranging in age from 1 to 130 months. Data on the age when trisomy 18 and trisomy 13 children achieved developmental skills were collected from a larger group of 62 trisomy 18 individuals and 14 trisomy 13 individuals whose families filled out parent questionnaires. Developmental quotient (DQ), defined as developmental age divided by chronological age, averaged 0.18 for trisomy 18 and 0.25 for trisomy 13. There was a dramatic drop in DQ from infancy to later childhood. The highest DQs and the greatest variation in DQs were in the first 2–3 years of life. Developmental ages in 7 skill areas were significantly different, with daily living and receptive language having the highest values and motor and communication skills having the lowest. When chronological age was taken into account, there was no significant difference in DQs in the same 7 skill areas, although there was a trend that was similar to the pattern of differences with developmental age. Older children could use a walker, understand words and phrases, use a few words and/or signs, crawl, follow simple commands, recognize and interact with others, and play independently. Walking and some toileting skills were also reported for trisomy 13. Although individuals with trisomy 18 and trisomy 13 were clearly functioning in the severe to profound developmentally handicapped range, they did achieve some psychomotor maturation and always continued to learn. © 1994 Wiley-Liss, Inc. 相似文献
52.
53.
F. Mattner D. Sohr A. Heim P. Gastmeier H. Vennema M. Koopmans 《Clinical microbiology and infection》2006,12(1):69-74
Norovirus infections have been described as self-limiting diseases of short duration. An investigation of a norovirus outbreak in a university hospital provided evidence for severe clinical features in patients with several underlying diseases. Clinical outcomes of norovirus infection were defined. Risk-factor analysis targeting underlying diseases and medication was performed using multivariate analyses. In five outbreak wards, 84 patients and 60 nurses were infected (an overall attack rate of 32% in patients, and 76% in nurses). The causative agent was the new variant Grimsby virus. Severe clinical features, including acute renal failure, arrhythmia and signs of acute graft organ rejection in renal transplant patients, were observed in seven (8.3%) patients. In multivariate analyses, cardiovascular disease (OR 17.1, 95% CI 2.17-403) and renal transplant (OR 13.0, 95% CI 1.63-281) were risk-factors for a potassium decrease of >20%. Age >65 years (OR 11.6, 95% CI 1.89-224) was a risk-factor for diarrhoea lasting >2 days. Immunosuppression (OR 5.7, 95% CI 1.78-20.1) was a risk-factor for a creatinine increase of >10%. Norovirus infections in patients with underlying conditions such as cardiovascular disease, renal transplant and immunosuppressive therapy may lead to severe consequences typified by decreased potassium levels, increased levels of C-reactive protein and creatine phosphokinase. In the elderly, norovirus infection may lead to an increased duration of diarrhoea. Therefore patients at risk should be hospitalised early and monitored frequently. Strict preventional measures should be implemented as early as possible to minimise the risk of nosocomial outbreaks. 相似文献
54.
55.
Linda J. Richards Trevor J. Kilpatrick Renee Dutton Seong-Seng Tan David P. Gearing Perry F. Bartlett Mark Murphy 《The European journal of neuroscience》1996,8(2):291-299
Previously we have shown that leukaemia inhibitory factor (LIF) potentiates the development of murine spinal cord neurons in vitro , suggesting that it, or related factors, may play an important regulatory role in neuronal development. We have further investigated this role and show here that the generation of neurons in cultures of embryonic day 10 spinal cord cells is inhibited by antibodies to the β subunit of the LIF receptor. Since there are more undifferentiated precursors in antibody-treated cultures than in control and LIF-treated cultures, it is concluded that the primary action of LIF, or related molecules, is to promote neuronal differentiation, not precursor survival. In addition, the failure of LIF to support neuronal survival in the period immediately following differentiation suggests that the increased numbers of neurons generated with LIF are not attributable to its neurotrophic action. By selecting neuronal precursors on the basis of their inability to express class I major histocompatibility complex molecules, it was shown that LIF acted directly upon these cells and not via an intermediary cell. LIF also appears to be involved in regulating the differentiation of astrocytes, since it increases the number of glial fibrillary protein (GFAP)-positive cells present in the cultures and since the spontaneous production of GFAP-positive cells is blocked by antibodies to the LIF β receptor. These findings suggest that LIF or related factors promote the differentiation of neural precursors in the spinal cord, but that they are not involved in preferentially promoting precursors down a specific differentiation pathway. 相似文献
56.
Heinrich Schulze Mönking Wilhelm P. Hornung Karl Stricker Gerhard Buchkremer 《European archives of psychiatry and clinical neuroscience》1997,247(1):31-34
This study examines the correlation between development of expressed emotion (EE) in relatives and course of illness of 99
DSM-III schizophrenic patients. Patients whose relatives were high EE at baseline and at the 2nd CFI approximately 20 months
later had a poor prognosis at the very outset of the study and an unfavourable course of illness. They had a higher rehospitalisation
rate, more symptoms, lower psychosocial assessment, and a poorer 2-year and even 8-year outcome. Patients from families with
a fluctuating EE or a consistently low EE had better courses. Expessed emotion is therefore a valid predictor not only of
symptomatic relapses, but also of other important aspects of schizophrenia. The connection between EE index and course of
illness seerns not to be simply reactive or causal, but complex and non-uniform. 相似文献
57.
58.
59.
Neuronal changes in the amygdala basolateral complex were studied during development and maturation in fetal and postnatal rat brains using morphometrical methods. Forty brains of animals of various ages were fixed in formalin, frozen and cut into 25 μm thick sections and stained with cresyl violet or haematoxylin and eosin (H&E). In cresyl violet preparations, the complex appeared for the first time on embryonic day (E)17 and was composed of two homogeneous nuclei—lateral and basolateral. On about the seventh postnatal day, each of these nuclei was divided into two parts—the first one into the dorsolateral and ventromedial and the second one into the anterior and posterior. Morphometric investigations showed a different increase of the neuronal and nuclear size in various parts of the basolateral complex up to postnatal day (P)14; after that time these parameters did not change significantly. The neuronal density and the total number of neurons stabilized at P7 in all parts of this complex, except for the dorsolateral part of the lateral nucleus in which a 30% decrease of the total number of cells was observed. From P14, in all nuclei under study, the total number of neurons did not change significantly. 相似文献
60.
Edwina J. Popek R. Weslie Tyson Gary J. Miller Sherrie A. Caldwell 《Fetal and pediatric pathology》1991,11(1):1-29
Prune belly syndrome (PBS) has been recognized since 1950 as the triad of absent abdominal wall musculature, undescended testes, and urinary tract anomalies. The etiology, however, remains uncertain. Theories of mesenchymal maldevelopment, obstruction, and genetic origin have been proposed. To evaluate the role of lower urinary tract obstruction as it relates to prostatic development and PBS, we studied the lower urinary tract of 15 cases of PBS, 8 cases of posterior urethral values (PUV), and 34 age-matched controls. It is generally accepted that prostatic growth and development are dependent on mesenchymal-epithelial interactions. We evaluated the mesenchymal and epithelial differentiation and relationships, and found distinctly different and consistent abnormalities between PBS and PUV as compared with one another and controls. The findings suggest that in PBS, prostatic growth and development are hindered because of destruction or absence of the appropriate primitive mesenchyme. Our studies could not definitely exclude very early obstruction as a cause of the findings because of lack of appropriate fetal material. 相似文献