全文获取类型
收费全文 | 1447821篇 |
免费 | 123014篇 |
国内免费 | 6528篇 |
专业分类
耳鼻咽喉 | 17759篇 |
儿科学 | 46135篇 |
妇产科学 | 38836篇 |
基础医学 | 200935篇 |
口腔科学 | 39567篇 |
临床医学 | 130446篇 |
内科学 | 300051篇 |
皮肤病学 | 33679篇 |
神经病学 | 121109篇 |
特种医学 | 60063篇 |
外国民族医学 | 282篇 |
外科学 | 224029篇 |
综合类 | 32305篇 |
现状与发展 | 3篇 |
一般理论 | 505篇 |
预防医学 | 120106篇 |
眼科学 | 29946篇 |
药学 | 100687篇 |
5篇 | |
中国医学 | 2461篇 |
肿瘤学 | 78454篇 |
出版年
2018年 | 15646篇 |
2017年 | 12538篇 |
2016年 | 14894篇 |
2015年 | 16659篇 |
2014年 | 23169篇 |
2013年 | 34051篇 |
2012年 | 42854篇 |
2011年 | 45632篇 |
2010年 | 27931篇 |
2009年 | 27513篇 |
2008年 | 42254篇 |
2007年 | 44913篇 |
2006年 | 45779篇 |
2005年 | 44134篇 |
2004年 | 41621篇 |
2003年 | 40402篇 |
2002年 | 38102篇 |
2001年 | 69724篇 |
2000年 | 71522篇 |
1999年 | 59895篇 |
1998年 | 18191篇 |
1997年 | 16265篇 |
1996年 | 17246篇 |
1995年 | 17227篇 |
1994年 | 16012篇 |
1993年 | 15042篇 |
1992年 | 49367篇 |
1991年 | 47808篇 |
1990年 | 45964篇 |
1989年 | 43668篇 |
1988年 | 40454篇 |
1987年 | 39573篇 |
1986年 | 37272篇 |
1985年 | 35991篇 |
1984年 | 27353篇 |
1983年 | 22992篇 |
1982年 | 14334篇 |
1981年 | 12876篇 |
1980年 | 12083篇 |
1979年 | 24320篇 |
1978年 | 17542篇 |
1977年 | 14784篇 |
1976年 | 13494篇 |
1975年 | 14071篇 |
1974年 | 16497篇 |
1973年 | 15794篇 |
1972年 | 14527篇 |
1971年 | 13383篇 |
1970年 | 12167篇 |
1969年 | 11370篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
991.
Stevens-Johnson syndrome during anti-tuberculosis chemotherapy in HIV-seropositive patients: report on six cases 总被引:1,自引:0,他引:1
Hypersensitivity reactions may occur during antituberculous chemotherapy. Severe reactions are rare, and in the three years 1983-86 during which we have both worked in Africa managing large numbers of patients with tuberculosis we only saw one or two cases with severe and generalised cutaneous hypersensitivity. In the last 12 months, however, there have been a number of cases with severe Stevens-Johnson syndrome which developed during antituberculous chemotherapy and has invariably been associated with seropositivity to HIV (human immunodeficiency virus). 相似文献
992.
Hemorrhage associated with mandibular osteotomies, especially to the extent that it becomes life threatening, is a rare occurrence and its risk is less than that following maxillary orthognathic surgery. Twenty-one cases of significant bleeding following mandibular sagittal split ramus osteotomies, vertical and oblique ramus osteotomies, and genioplasties are presented. Life-threatening hemorrhage associated with mandibular osteotomies is primarily an intraoperative problem and the incidence of major postoperative and recurrent hemorrhage is not as great as following maxillary osteotomies. Suggestions for the avoidance and treatment of these bleeding complications are discussed. 相似文献
993.
994.
A V Levy E Laska J D Brodie N D Volkow A P Wolf 《Journal of cerebral blood flow and metabolism》1991,11(2):A103-A113
We introduce the concept of the metabolic centroid spectrum as the feature space to characterize the distribution of metabolic activity in three-dimensional brains. The method computes the metabolic centroid of a brain subvolume for each increment of metabolic activity occurring in the whole brain. The result is the metabolic spectral signature, a continuous three-dimensional curve whose shape reflects the distribution of metabolic rates in the brain. The method's sensitivity to metabolic distribution asymmetries is greatly increased over that of the metabolic centroid method, while retaining its advantages; it is almost invariant to head size, head positioning, photon scatter, and the positron emission tomography (PET) camera's full width at half-maximum. It does not require magnetic resonance, computed tomography, or x-ray images. To test the method we analyzed the metabolic PET images of 40 normal subjects and 20 schizophrenics. The results show a unification of several metabolic characteristics of schizophrenic brains, such as laterality, hypofrontality, cortical/subcortical abnormalities, and overall brain hypometabolism, which were identified by different laboratories in separate studies using differing methodologies. Here they are presented by a single automatic objective method. 相似文献
995.
D Guidetti F Gemignani S Terenziani P Ragni G Fornaciari D Dall'Asta A Marbini 《Acta neurologica Belgica》1991,91(1):12-19
Three patients with hypereosinophilia showed different forms of peripheral neuropathy: severe polyneuropathy of prevalently sensory type (case 1), mild sensory neuropathy (case 2), acute mononeuropathy of the median nerve with subclinical polyneuropathy (case 3). Hypereosinophilia was probably idiopathic, however the presence of atypical findings suggested transition to vasculitides or collagen disease. Sural nerve biopsy in cases 1 and 2 showed features of axonopathy in both, although of different severity, reflecting the variability of clinical involvement and, probably, heterogeneous pathogenic mechanisms. Peripheral nerve involvement associated with hypereosinophilia may be related to neurotoxicity of eosinophils, or to vascular damage. 相似文献
996.
D Mezzano G E del Pino M Montesinos M E García E Aranda A Foradori 《Thrombosis and haemostasis》1991,66(2):254-258
Thrombocytopenia was induced in mongrel dogs by two mechanisms: immunologically, by intravenous injection of heterologous antiplatelet antibody, and non-immunologically, by circulating the blood through glass beads in anesthetized animals. The platelet content of 5-HT was monitored before and during the recovery of the blood platelet counts. This period is associated with the normalization of the mean platelet survival time and with a progressive increase in the mean age of the circulating platelet population. A continuous increment in platelet 5-HT closely followed the increase in platelet counts in both models of thrombocytopenia, and a strong correlation was found between the platelet age and 5-HT content. These findings support the concept that platelets accumulate 5-HT during their physiological aging process, contradicting the notion that a negative balance in 5-HT content results at the end of their physiological lifespan in circulation. These results are not in conflict with the concept that circulating platelets release and re-uptake 5-HT. 相似文献
997.
C W Scott D P Blowers P T Barth M M Lo A I Salama C B Caputo 《Journal of neuroscience research》1991,30(1):154-162
Three isoforms of human tau protein were compared for their abilities to induce microtubule assembly. The three isoforms, tau 3 (tau containing three microtubule-binding domains), tau 4 (tau containing four microtubule-binding domains) and tau 4L (tau containing four microtubule binding domains plus a 58-amino-acid insert near the N-terminus) were expressed in E. coli and purified using ammonium sulfate precipitation, ion exchange, and size exclusion chromatography. All three isoforms induced microtubule assembly at micromolar concentrations and showed similar critical concentrations for assembly of 0.4-0.45 microM. However, tau 4 induced microtubule formation at a rate five- to tenfold faster than either tau 3 or tau 4L. The rate of microtubule elongation seen with tau 4 was twofold greater than with tau 3 or tau 4L, suggesting that the faster rate of microtubule assembly seen with tau 4 was due, at least in part, to faster elongation. Tau 4 induced a greater number of microtubules to form at steady state than did tau 3 or tau 4L. The microtubules generated with each tau isoform had similar steady-state length distributions and were equally susceptible to cold-induced disassembly. These results indicate that the additional microtubule-binding domain in tau 4 enhances microtubule assembly, while the 58-amino-acid insert negates the stimulatory effect of the fourth microtubule-binding domain. 相似文献
998.
999.
In order to clarify the reported discrepancies in S100 alpha protein and mRNA distribution in rat tissues, a rat S100 alpha cDNA has been isolated and this species homologous probe along with a rat S100 beta cDNA probe has been used to examine S100 mRNA expression in rat tissues. Although the rat S100 alpha cDNA was missing approximately 30 nucleotides of coding sequence, only 4 conservative changes in amino acid sequence were observed when the deduced amino acid sequence was compared to the bovine S100 alpha amino acid sequence. Thus, S100 alpha proteins, like S100 beta proteins, are highly conserved among species. All nineteen of the tissues examined (including cerebrum and cerebellum) contained S100 alpha mRNA. In addition, S100 beta mRNA was detected in thirteen of the nineteen tissues examined. These results are in agreement with previous protein distribution studies and further demonstrate that S100 proteins are not brain-specific and are expressed in a large number of tissues. Although S100 alpha and S100 beta mRNAs were detected in rat tissues which had previously been reported to contain S100 alpha and S100 beta protein, a direct correlation between the protein and mRNA levels were not observed, suggesting that different mechanisms regulate S100 expression in various tissues. S100 alpha exhibited a single similar size mRNA species (0.5 Kb) in all tissues examined, as did S100 beta (1.5 Kb), suggesting that the individual S100 proteins are expressed as single mRNA and protein products in rat tissues. 相似文献
1000.
N M Whear J D Langdon D W Macpherson 《International journal of oral and maxillofacial surgery》1991,20(6):357-359
A new surgical technique for the treatment of recurrent temporomandibular joint subluxation or dislocation is described. Following a horizontal osteotomy and down-fracture of the articular eminence an inter-positional bovine cartilage xenograft is inserted in order to augment the vertical height of the eminence. The procedure combines simplicity with minimal post-operative morbidity. The increase in eminence height is both predictable and stable. 相似文献