全文获取类型
收费全文 | 1844篇 |
免费 | 157篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 99篇 |
儿科学 | 70篇 |
妇产科学 | 21篇 |
基础医学 | 195篇 |
口腔科学 | 39篇 |
临床医学 | 232篇 |
内科学 | 318篇 |
皮肤病学 | 12篇 |
神经病学 | 121篇 |
特种医学 | 284篇 |
外科学 | 188篇 |
综合类 | 47篇 |
预防医学 | 100篇 |
眼科学 | 59篇 |
药学 | 77篇 |
中国医学 | 5篇 |
肿瘤学 | 143篇 |
出版年
2023年 | 11篇 |
2022年 | 8篇 |
2021年 | 24篇 |
2020年 | 13篇 |
2019年 | 18篇 |
2018年 | 49篇 |
2017年 | 25篇 |
2016年 | 36篇 |
2015年 | 34篇 |
2014年 | 56篇 |
2013年 | 55篇 |
2012年 | 82篇 |
2011年 | 67篇 |
2010年 | 55篇 |
2009年 | 78篇 |
2008年 | 76篇 |
2007年 | 61篇 |
2006年 | 53篇 |
2005年 | 50篇 |
2004年 | 70篇 |
2003年 | 47篇 |
2002年 | 28篇 |
2001年 | 46篇 |
2000年 | 36篇 |
1999年 | 39篇 |
1998年 | 64篇 |
1997年 | 64篇 |
1996年 | 76篇 |
1995年 | 58篇 |
1994年 | 54篇 |
1993年 | 59篇 |
1992年 | 33篇 |
1991年 | 37篇 |
1990年 | 42篇 |
1989年 | 61篇 |
1988年 | 50篇 |
1987年 | 44篇 |
1986年 | 44篇 |
1985年 | 33篇 |
1984年 | 26篇 |
1983年 | 19篇 |
1982年 | 26篇 |
1981年 | 20篇 |
1980年 | 14篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 12篇 |
1976年 | 14篇 |
1975年 | 15篇 |
1963年 | 2篇 |
排序方式: 共有2010条查询结果,搜索用时 78 毫秒
21.
22.
Carol Smillie B.N. B.Ed. M.S.C. Katherine Coffin B.A. ME.D. Kathryn Porter B.A. Brenda Ryan B.A. M.B.A. 《Journal of community health》1988,13(3):156-170
The International Conference on Primary Health Care, meeting in Alma-Ata, in the Soviet Union, September 12, 1978, expressed the need for urgent action by all governments, all health and development workers and the world community, to protect and promote the health of all people of the world. The world was caught by the phrase which emerged from this conference, Health For All by the Year 2000 and many have examined the articles of the Alma-Ata declaration and tried to implement them in their corner of the world. This paper describes a community-based smoking-cessation program which was implemented in the province of Nova Scotia, Canada, during the years 1980–1984. Primary to this project was the belief that people have the right and the duty to participate individually and collectively in planning and implementing their health care. This paper describes one community's effort in putting this belief into practice.Carol Smillie, B.N. BE.d. M.S.c. is an Assistant Professor at the School of Nursing, Dalhousie University, Halifax, Nova Scotia, Canada B3H 3J5, Katherine Coffin, BA, MEd is the Program Officer, Nova Scotia Office, Health Promotion Directorate Health and Welfare Canada, 5251 Duke Street, Halifax, Nova Scotia. Canada B3J 1P3. Kathryn Porter, B.A. (Gen)., is the Information and Education Coordinator, Nova Scotia Division Canadian Cancer Society. Brenda Ryan, B.A., M.B.A. is Program Evaluation Analysist, Nova Scotia Department of Health, 6088 Hollis Street, Halifax. Nova Scotia, Canada. This Project was funded by Health and Welfare Canada, Nova Scotia Department of Health, Nova Scotia Division Canadian Cancer Society, Requests for reprints should be addressed to: Professor Carol Smillie. 相似文献
23.
Androgen receptor YAC transgenic mice carrying CAG 45 alleles show trinucleotide repeat instability 总被引:1,自引:15,他引:1
La Spada AR; Peterson KR; Meadows SA; McClain ME; Jeng G; Chmelar RS; Haugen HA; Chen K; Singer MJ; Moore D; Trask BJ; Fischbeck KH; Clegg CH; McKnight GS 《Human molecular genetics》1998,7(6):959-967
X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG
repeat expansion in the first exon of the androgen receptor (AR) gene.
Disease-associated alleles (37-66 CAGs) change in length when transmitted
from parents to offspring, with a significantly greater tendency to shift
size when inherited paternally. As transgenic mice carrying human AR cDNAs
with 45 and 66 CAG repeats do not display repeat instability, we attempted
to model trinucleotide repeat instability by generating transgenic mice
with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions
in their genomic context. Studies of independent lines of AR YAC transgenic
mice with CAG 45 alleles reveal intergenerational instability at an overall
rate of approximately 10%. We also find that the 45 CAG repeat tracts are
significantly more unstable with maternal transmission and as the
transmitting mother ages. Of all the CAG/CTG repeat transgenic mice
produced to date the AR YAC CAG 45 mice are unstable with the smallest
trinucleotide repeat mutations, suggesting that the length threshold for
repeat instability in the mouse may be lowered by including the appropriate
flanking human DNA sequences. By sequence-tagged site content analysis and
long range mapping we determined that one unstable transgenic line has
integrated an approximately 70 kb segment of the AR locus due to
fragmentation of the AR YAC. Identification of the cis - acting elements
that permit CAG tract instability and the trans -acting factors that
modulate repeat instability in the AR YAC CAG 45 mice may provide insights
into the molecular basis of trinucleotide repeat instability in humans.
相似文献
24.
25.
Applicability of a real-time quantitative PCR assay for diagnosis of respiratory syncytial virus infection in immunocompromised adults 总被引:5,自引:0,他引:5
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
van Elden LJ van Loon AM van der Beek A Hendriksen KA Hoepelman AI van Kraaij MG Schipper P Nijhuis M 《Journal of clinical microbiology》2003,41(9):4378-4381
Respiratory syncytial virus (RSV) accounts for the majority of respiratory virus infections, producing high mortality rates in immunocompromised patients with hematologic malignancies. The available methods for the rapid detection of RSV by antigen detection or PCR either lack sensitivity, require complex laboratory manipulation, or have not been evaluated in this patient population. To assess the applicability of a TaqMan-based real-time PCR technique for the detection of RSV A and B in immunocompromised adults, we developed a rapid, sensitive detection method that simultaneously detects RSV A and B and can be applied in routine diagnostics. The specificity of the assay was assessed using a panel of reference strains of other respiratory viruses and RSV. Electron microscopy-counted stocks of RSV A and B were used to develop a quantitative PCR format. Eleven copies of viral RNA could be detected for RSV A strain Long, and 14 copies could be detected for RSV B strain 9320, corresponding to 50% tissue culture infective doses of 0.86 and 0.34, respectively. The assay was evaluated on 411 combined nose and throat swabs derived from immunocompromised adults with or without signs of respiratory tract infection. The diagnostic efficacy of the TaqMan PCR determined on the clinical samples showed that this real-time PCR technique was substantially more sensitive than the combination of conventional viral culture and shell vial culture. None of the clinical specimens derived from patients without signs of respiratory illness were found to be positive for RSV by real-time TaqMan PCR. 相似文献
26.
Tumour necrosis factor-alpha stimulates invasiveness of T-cell hybridomas and cytotoxic T-cell clones by a pertussis toxin-insensitive mechanism.
下载免费PDF全文
![点击此处可从《Immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tumour necrosis factor-alpha (TNF-alpha) stimulated invasion by mouse T-cell hybridomas and cytotoxic T-lymphocyte clones into rat embryo fibroblast monolayers. The effect on these highly invasive cells was limited: invasion was stimulated maximally to 130% of controls. However, when cells were pretreated with pertussis toxin (PT), which inhibits invasion to +/- 20% of controls, a clearcut effect was observed: 400 U TNF-alpha per ml stimulated invasion usually two- to threefold, and sometimes even up to 10-fold. Therefore, experiments were done with PT-pretreated cells. Stimulation was dose dependent and maximal at 200-400 U TNF-alpha per ml. An anti-TNF-alpha monoclonal antibody completely abolished TNF-alpha-induced invasion. The effect was maximal 30 min after addition of cells and TNF-alpha to the monolayer and then declined. TNF-alpha preincubation of T-cell hybridoma cells, but not of fibroblasts, had a similar stimulatory effect, which was also maximal after 30 min. This shows that TNF-alpha acts directly on the T-cell hybridoma cells. Invasive T-cell hybridomas colonize many tissues from the blood similarly as normal T cells. Our data thus suggest that TNF-alpha can stimulate migration of normal T lymphocytes into inflamed tissues and can promote metastasis of malignant T lymphomas. The signals involved are transmitted via a pertussis toxin-insensitive pathway. 相似文献
27.
Morphological analysis of degeneration and regeneration of syncytiotrophoblast in first trimester placental villi during organ culture 总被引:3,自引:1,他引:3
We have recently shown using dansyl-L-lysine exclusion studies that the
release of human chorionic gonadotrophin (HCG) in conjunction with L-
lactate dehydrogenase (LDH) from first trimester villi during organ culture
is symptomatic of syncytiotrophoblast degeneration. The purpose of this
study was to examine chorionic villi at the ultrastructural level in order
to determine events occurring during organ culture. The tissue was sampled
after 0, 24, 48 and 120 h in culture and processed for electron microscopy.
In addition to confirming the previously recorded syncytial degeneration,
the electron micrographs showed clearly the generation of a new
syncytiotrophoblast layer. The new layer, derived from differentiating
cytotrophoblast cells, was largely formed by 48 h and was maintained for at
least 120 h in culture. This study demonstrates a model which provides an
opportunity to study the differentiation of cytotrophoblast cells whilst
they retain their anatomical relationships within the villous structure.
相似文献
28.
29.
30.
Formaldehyde-induced fluorescence (FIF) of noradrenalin (NA) was studied in histochemical preparations of the rat iris. With the aid of a two-dimensional microfluorimetric scanning method, quantitative information was obtained from neuronal and non-neuronal elements selectively. Spectral analysis and fluorimetric studies showed the existence of extraneuronal NA in the iris of untreated rats. Surgical and pharmacological (reserpine, amphetamine, imipramine, nialamide) manipulation of sympathetic neurotransmission-induced changes in extraneuronal fluorescence, which did not parallel changes in fluorescence of neuronal elements. A positive relationship was found between changes in extraneuronal fluorescence and the postsynaptic effect (pupil diameter). We hypothesize that extraneuronal catecholamine (CA) fluorescence is a histochemical parameter for synaptic neurotransmission. 相似文献