全文获取类型
收费全文 | 10709篇 |
免费 | 867篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 58篇 |
儿科学 | 251篇 |
妇产科学 | 141篇 |
基础医学 | 1417篇 |
口腔科学 | 182篇 |
临床医学 | 1215篇 |
内科学 | 1727篇 |
皮肤病学 | 154篇 |
神经病学 | 1524篇 |
特种医学 | 525篇 |
外科学 | 1185篇 |
综合类 | 256篇 |
一般理论 | 11篇 |
预防医学 | 1198篇 |
眼科学 | 276篇 |
药学 | 799篇 |
中国医学 | 22篇 |
肿瘤学 | 654篇 |
出版年
2022年 | 67篇 |
2021年 | 150篇 |
2020年 | 89篇 |
2019年 | 136篇 |
2018年 | 165篇 |
2017年 | 135篇 |
2016年 | 178篇 |
2015年 | 209篇 |
2014年 | 245篇 |
2013年 | 333篇 |
2012年 | 504篇 |
2011年 | 514篇 |
2010年 | 330篇 |
2009年 | 280篇 |
2008年 | 507篇 |
2007年 | 513篇 |
2006年 | 493篇 |
2005年 | 501篇 |
2004年 | 489篇 |
2003年 | 469篇 |
2002年 | 471篇 |
2001年 | 259篇 |
2000年 | 354篇 |
1999年 | 311篇 |
1998年 | 174篇 |
1997年 | 138篇 |
1996年 | 155篇 |
1995年 | 120篇 |
1994年 | 109篇 |
1993年 | 110篇 |
1992年 | 209篇 |
1991年 | 214篇 |
1990年 | 280篇 |
1989年 | 185篇 |
1988年 | 205篇 |
1987年 | 178篇 |
1986年 | 154篇 |
1985年 | 167篇 |
1984年 | 129篇 |
1983年 | 119篇 |
1982年 | 105篇 |
1981年 | 104篇 |
1980年 | 69篇 |
1979年 | 89篇 |
1978年 | 85篇 |
1977年 | 53篇 |
1975年 | 62篇 |
1974年 | 54篇 |
1968年 | 55篇 |
1967年 | 49篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Evaluation of a new enzyme-linked immunosorbent assay test for rotavirus antigen in faeces 总被引:6,自引:0,他引:6
下载免费PDF全文
![点击此处可从《Journal of clinical pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A new commercial test for the diagnosis of rotavirus gastroenteritis was assessed. With some modifications it compared favourably with electron microscopy and immunofluorescence. 相似文献
82.
Competitive control of the self-renewing T cell repertoire 总被引:1,自引:0,他引:1
We develop a mathematical model for the self-renewing part of the T cell
repertoire. Assuming that self-renewing T cells have to be stimulated by
immunogenic MHC-peptide complexes presented on the surfaces of
antigen-presenting cells, we derive a model of T cell growth in which
competition for MHC-peptide complexes limits T cell clone sizes and
regulates the total number of self-renewing T cells in the animal. We show
that for a sufficient diversity and/or degree of cross-reactivity, the
total T cell number hardly depends upon the diversity of the T cell
repertoire or the diversity of the set of presented peptides. Conversely,
for repertoires of lower diversity and/or cross-reactivity, steady-state
total T cell numbers may be limited by the diversity of the T cells. This
provides a possible explanation for the limited repertoire expansion in
some, but not all, mouse T cell re-constitution experiments. We suggest
that the competitive interactions described by our model underlie the
normal T cells numbers observed in transgenic mice, germ-free mice and
various knockout mice.
相似文献
83.
Dr. V. H. Perry A. Cowey 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1979,35(1):97-108
Summary Several months after unilateral removal of the striate cortex or superior colliculus, or both, in infant and adult rats the retinal projections were studied autoradiographically. The retinal projection areas in adult-operated animals were not different from those of unoperated controls, but aberrant pathways were found in the infant group. Following removal of striate cortex there was a small aberrant pathway to the lateral posterior nucleus of the thalamus (LP) and possibly to the pretectum. After removal of the superior colliculus there was a conspicuous aberrant projection to LP, which was even more prominent after combined removal of striate cortex and superior colliculus. The results support the proposal that when the normal field of termination is damaged, either directly by a tectal lesion or indirectly by a cortical lesion, axons grow and innervate LP, which has been partly deafferented by the lesion and which consequently possesses vacant synaptic space. Although the different consequences of early and late lesions may indicate that only infantile damaged terminals can redistribute themselves an alternative is that in infants many axons have not yet reached their normal terminal sites at the time of operation and that only those axons have the ability to continue growing and to form an aberrant pathways. The role of the aberrant pathway in vision is unknown. 相似文献
84.
Contribution of redox-active iron and copper to oxidative damage in Alzheimer disease 总被引:1,自引:0,他引:1
Castellani RJ Honda K Zhu X Cash AD Nunomura A Perry G Smith MA 《Ageing research reviews》2004,3(3):319-326
Metal-catalyzed hydroxyl radicals are potent mediators of cellular injury, affecting every category of macromolecule, and are central to the oxidative injury hypothesis of Alzheimer disease (AD) pathogenesis. Studies on redox-competent copper and iron indicate that redox activity in AD resides exclusively within the neuronal cytosol and that chelation with deferoxamine, DTPA, or, more recently, iodochlorhydroxyquin, removes this activity. We have also found that while proteins that accumulate in AD possess metal-binding sites, metal-associated cellular redox activity is primarily dependent on metals associated with nucleic acid, specifically cytoplasmic RNA. These findings indicate aberrations in iron homeostasis that, we suspect, arise primarily from heme, since heme oxygenase-1, an enzyme that catalyzes the conversion of heme to iron and biliverdin, is increased in AD, and mitochondria, since mitochondria turnover, mitochondrial DNA, and cytochrome C oxidative activity are all increased in AD. These findings, as well as studies demonstrating a reduction in microtubule density in AD neurons, suggest that mitochondrial dysfunction, acting in concert with cytoskeletal pathology, serves to increase redox-active heavy metals and initiates a cascade of abnormal events culminating in AD pathology. 相似文献
85.
Chemotherapeutic agents are associated with a number of serious side-effects. In addition to the development of peripheral neuropathy, patients often complain of additional symptoms related to attentional mechanisms. Although a great deal of interest is directed towards understanding the mechanisms underlying the development of peripheral neuropathy, there is a paucity of research that has examined the extent of impairment of attention in animals receiving chemotherapeutic agents. Therefore, the purpose of this experiment was to examine attentional mechanisms using the method of pre-pulse inhibition in animals that were chronically treated with vincristine. Although vincristine treated animals developed signs of peripheral neuropathy, there was no associated alteration of pre-pulse inhibition relative to vehicle treated animals. These results highlight the importance of continuing to develop methodology to model symptom burden in patients receiving chemotherapy. 相似文献
86.
87.
Mechanisms for differential block among single myelinated and non-myelinated axons by procaine 总被引:7,自引:0,他引:7
下载免费PDF全文
![点击此处可从《The Journal of physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
1. The differential sensitivity of saphenous nerve fibres in the cat to block by procaine HCl was re-examined by recording identifiable unit action potentials from small nerve filaments.2. Small myelinated axons were blocked more quickly than large myelinated axons, but this differential effect could not be accounted for by differences in anaesthetic concentration requirements.3. The onset of block in non-myelinated axons was slower than or equal to that of small myelinated axons depending on anaesthetic concentration.4. Absolute differential block of non-myelinated and small myelinated axons was obtained by limiting the length of axons exposed to procaine to 2 mm.5. Differential rates of blocking among myelinated axons appear to depend on differences in the length of axons that must be exposed to blocking concentrations of procaine and to arise from the irregular distribution of such concentrations within an exposed nerve. 相似文献
88.
89.
Interpretation of gram-stained sputa containing Moraxella (Branhamella) catarrhalis. 总被引:1,自引:0,他引:1
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)
S M Ainsworth S B Nagy L A Morgan G R Miller J L Perry 《Journal of clinical microbiology》1990,28(11):2559-2560
Sputum specimens culture positive for Moraxella (Branhamella) catarrhalis were Gram stained with three decolorizer solutions (slow, 95% ethyl alcohol; intermediate, 1:1 ratio of 95% ethyl alcohol and acetone; and fast, acetone alone) for 5, 10, 20, and 30 s. Optimal results were obtained with acetone alone after 10 s or with a 1:1 mixture of acetone and ethanol after 20 s. Inadequate decolorization of M. catarrhalis in sputa is likely if the decolorization solution and exposure time are not optimal and may contribute to underreporting of this organism. 相似文献
90.
Use of post-mortem human synaptosomes for studies of metabolism and transmitter amino acid release 总被引:2,自引:0,他引:2
J A Hardy P R Dodd A E Oakley A M Kidd R H Perry J A Edwardson 《Neuroscience letters》1982,33(3):317-322
Synaptosomes have been prepared from human brain obtained at autopsies carried out up to 24 h postmortem (p.m.). They showed generally good retention of morphology, as well as accumulation of tissue potassium and linear rates of oxygen uptake. In response to veratrine depolarization they showed increased respiration rate, decreased tissue potassium content and the specific release of transmitter amino acids. Regression analysis indicated that metabolically and functionally active preparations may be obtained up to ca. 25 h p.m. Preparations obtained from patients dying with brain injury were inactive. 相似文献