全文获取类型
收费全文 | 45574篇 |
免费 | 4982篇 |
国内免费 | 71篇 |
专业分类
耳鼻咽喉 | 635篇 |
儿科学 | 1297篇 |
妇产科学 | 1261篇 |
基础医学 | 7055篇 |
口腔科学 | 1062篇 |
临床医学 | 6142篇 |
内科学 | 8468篇 |
皮肤病学 | 609篇 |
神经病学 | 3633篇 |
特种医学 | 1576篇 |
外国民族医学 | 1篇 |
外科学 | 6062篇 |
综合类 | 1013篇 |
一般理论 | 29篇 |
预防医学 | 4699篇 |
眼科学 | 677篇 |
药学 | 3646篇 |
中国医学 | 62篇 |
肿瘤学 | 2700篇 |
出版年
2021年 | 622篇 |
2020年 | 409篇 |
2019年 | 703篇 |
2018年 | 805篇 |
2017年 | 584篇 |
2016年 | 727篇 |
2015年 | 768篇 |
2014年 | 1054篇 |
2013年 | 1588篇 |
2012年 | 2125篇 |
2011年 | 2174篇 |
2010年 | 1243篇 |
2009年 | 1115篇 |
2008年 | 1914篇 |
2007年 | 1974篇 |
2006年 | 1925篇 |
2005年 | 1881篇 |
2004年 | 1799篇 |
2003年 | 1749篇 |
2002年 | 1778篇 |
2001年 | 1573篇 |
2000年 | 1598篇 |
1999年 | 1391篇 |
1998年 | 655篇 |
1997年 | 546篇 |
1996年 | 458篇 |
1995年 | 486篇 |
1994年 | 462篇 |
1993年 | 426篇 |
1992年 | 1122篇 |
1991年 | 1058篇 |
1990年 | 1035篇 |
1989年 | 960篇 |
1988年 | 884篇 |
1987年 | 924篇 |
1986年 | 874篇 |
1985年 | 897篇 |
1984年 | 708篇 |
1983年 | 608篇 |
1982年 | 441篇 |
1981年 | 353篇 |
1980年 | 366篇 |
1979年 | 579篇 |
1978年 | 448篇 |
1977年 | 365篇 |
1976年 | 376篇 |
1974年 | 379篇 |
1973年 | 333篇 |
1972年 | 338篇 |
1971年 | 304篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
23.
David W. Farley DDS John D. Jones DDS Robert J. Cronin DDS MS 《Journal of prosthodontics》1998,7(2):84-90
Phonetics, esthetics, function, and comfort form the foundation of a successful dental prosthesis. A review of the mechanics of speech as well as common speech problems encountered with a removable maxillary prosthesis are presented. The use of a palatogram to aid the clinician in the assessment and resolution of speech problems associated with a maxillary denture is demonstrated. 相似文献
24.
A P Jones A Sofat C H Davis S Denton N T Gurusinghe 《British journal of neurosurgery》1990,4(3):193-197
The high cost of commercial CT-compatible stereotactic frames has restricted the availability of CT-guided stereotaxy for many neurosurgical centres. However, many of these centres do possess the standard stereotactic frames for projection radiography, of which the old type Leksell frame is probably the most common. We have devised a simple and low-cost modification to an old Leksell frame to allow CT-guided stereotaxy. The nature of the modifications allow complete freedom of positioning of the frame relative to the CT scanner and coordinate transformations can be performed simply and effectively. The modified frame has been used successfully for some 18 months and the modification has now been performed at two centres in the North West Regional Health Authority. We hope this modification will allow many other centres to embark on CT-guided stereotaxy. 相似文献
25.
26.
Paired helical filaments (PHFs) constitute the majority of filaments in neurofibrillary tangles (NFTs), an Alzheimer's disease (AD) characteristic. PHFs consists of two filaments helically twisted around one another in a regular pattern. The effects of possible PHF-inducing candidates, namely aluminium and glutamate, were observed at the ultrastructural level in this investigation. Rat cerebral explants were exposed to aluminium, citric acid and glutamate singly or combined from 7–12 days in vitro (DIV), while control explants remained in basal medium. On 12 DIV, explants were processed for EM. Three–four EM explants were serially sectioned per condition. Ten 60 nm sections from five systematically sampled areas per explant were collected. One section was randomly chosen per sampled area and all neurons within it observed at 81 200– to record the presence of accumulations of curved filaments (CFs), straight filaments (SFs) or PHFs. Using stereological methods, absolute numbers and the percentage incidence of CFs and SFs were calculated. A significant increase in the frequency of neurons containing CF aggregations in aluminium explants compared to glutamate explants was found. There were no significant differences between conditions for neurons containing SF accumulations. Possible PHFs were observed in one aluminium/glutamate-treated explant. These results suggest that aluminium alone can cause significant formation of accumulations of C- or S-shaped CFs, some of which are double-stranded and twisted around one another regularly. However, structures that were possibly PHF-like were only observed in one aluminium-treated explant, thus making it premature to draw an association between aluminium and the induction of AD-like pathology. 相似文献
27.
The involvement of children in research studies is historically fraught with difficulties. Experiments on children without their consent or knowledge have been carried out in the past and thus the need for stringent ethical control is undoubtedly necessary. However this paper argues that the need to protect children from unethical research has somehow become entwined in the web of secrecy that surrounds the very nature of child abuse. In the name of 'protection' are children in danger of not having their voice heard?
In the foreword to 'Listening to Children' (Alderson, 1995) Roger Singleton writes, 'much research is carried out on and about children, but seldom with children. Children themselves are often strangely silent'. This paper draws on recent literature on the institutional abuse of young people in residential care and the lack of voice that those abused in residential care have traditionally had, suggesting that their silence is not 'strange' but perhaps contrived.
This paper does not repeat the work of Alderson (1995) and make suggestions as to how research with children may best be carried out, but seeks to address the issues in relation to research with children who are in institutions. 相似文献
In the foreword to 'Listening to Children' (Alderson, 1995) Roger Singleton writes, 'much research is carried out on and about children, but seldom with children. Children themselves are often strangely silent'. This paper draws on recent literature on the institutional abuse of young people in residential care and the lack of voice that those abused in residential care have traditionally had, suggesting that their silence is not 'strange' but perhaps contrived.
This paper does not repeat the work of Alderson (1995) and make suggestions as to how research with children may best be carried out, but seeks to address the issues in relation to research with children who are in institutions. 相似文献
28.
M. Isohanni T. Mäkikyrö J. Moring P. Räsanen H. Hakko U. Partanen M. Koiranen P. Jones 《Social psychiatry and psychiatric epidemiology》1997,32(5):303-308
As a prerequisite to the use of the Finnish National Hospital Discharge Register in psychiatric epidemiological research, we studied the diagnostic reliability of the register in terms of the psychiatric morbidity experienced by a national birth cohort. We investigated all entries to the register for a sample based upon the Northern Finland 1966 birth cohort at the age of 16 years (n=11017). Until the end of 1993 (age 27 years), a total of 563 subjects had a register diagnosis indicating a psychiatric illness, 37 of them being schizophrenia. When operational criteria (DSM-III-R) were applied to clinical information in the available original hospital records for cases of psychosis, personality disorder and substance abuse (n=249), 71 fulfilled criteria for schizophrenia, including all of the 37 cases in the register and an additional 34 (48% false-negatives), most frequently diagnosed in the register as schizophreniform or other psychosis. Despite the official use of DSM-III-R nomenclature, it appears that the clinical concept of schizophrenia in Finland, manifest within the register, remains very restrictive. The application of operational criteria is a necessary prerequisite for scientific research on schizophrenia. 相似文献
29.
30.
Eros S. Chaves Robert C. Wood Archie A. Jones Dewey A. Newbold Mary A. Manwell Kenneth S. Kornman 《Journal of clinical periodontology》1993,20(2):139-143
Abstract Bleeding on probing (BOP) and the gingival index have been used to clinically characterize the degree of gingival inflammation. It is, however, unclear to what extent these parameters correlate to each other and to probing pocket depth (PD). The purpose of this clinical study was to evaluate the association between BOP and GI bleeding (scores of 2 and 3), as well as the relationship of these variables to PD, in a group of patients presenting with naturally-occurring gingivitis. Based on screening examinations of 125 subjects with at least 20 teeth, no more than 4 sites with PD over 6 mm, a BOP frequency of 30% or greater, and no systemic condition that would influence the inflammatory response, were selected. 2 weeks after screening they were examined at 6 sites per tooth for plaque index, GI, PD and BOP. A standardized pressure sensitive probe (Florida Probe) with 20 g probing force was used for BOP and PD measurements. In this population, means of 40.9% (S.E.= 1.36) BOP sites and 35.3% (S.E, = 1.81) GI bleeding sites per patient were found. A total of 20,008 sites ranging in PD up to 5.9 mm were evaluated; however, the majority of sites (19,723, 98.6%) presented with <4 mm PD. When sites were evaluated, BOP demonstrated a positive correlation with PD, whereas GI bleeding correlated with PH. For sites characterized by the absence of BOP as well as the absence of GI bleeding (scores 0 and 1), the highest % of agreement between the 2 indices (77.7%) was found in shallow sites (0.1–2 mm). In contrast, when sites presenting with both BOP and GI bleeding were analyzed, the highest % of agreement (85,4%) was found for sites with PD >4.0 mm. In this gingivitis population group, it appears that BOP and GI bleeding evaluate distinct inflammatory1 conditions of the gingival tissues, and the relationship between the 2 clinical parameters may vary according to PD at the individual site examined. 相似文献