全文获取类型
收费全文 | 4565篇 |
免费 | 303篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 133篇 |
妇产科学 | 77篇 |
基础医学 | 566篇 |
口腔科学 | 348篇 |
临床医学 | 352篇 |
内科学 | 1160篇 |
皮肤病学 | 80篇 |
神经病学 | 317篇 |
特种医学 | 327篇 |
外科学 | 442篇 |
综合类 | 65篇 |
预防医学 | 408篇 |
眼科学 | 62篇 |
药学 | 346篇 |
中国医学 | 29篇 |
肿瘤学 | 130篇 |
出版年
2023年 | 53篇 |
2022年 | 90篇 |
2021年 | 182篇 |
2020年 | 106篇 |
2019年 | 137篇 |
2018年 | 168篇 |
2017年 | 119篇 |
2016年 | 123篇 |
2015年 | 153篇 |
2014年 | 204篇 |
2013年 | 254篇 |
2012年 | 301篇 |
2011年 | 336篇 |
2010年 | 186篇 |
2009年 | 169篇 |
2008年 | 241篇 |
2007年 | 246篇 |
2006年 | 184篇 |
2005年 | 199篇 |
2004年 | 123篇 |
2003年 | 119篇 |
2002年 | 127篇 |
2001年 | 91篇 |
2000年 | 73篇 |
1999年 | 66篇 |
1998年 | 90篇 |
1997年 | 68篇 |
1996年 | 80篇 |
1995年 | 54篇 |
1994年 | 63篇 |
1993年 | 53篇 |
1992年 | 24篇 |
1991年 | 27篇 |
1990年 | 25篇 |
1989年 | 56篇 |
1988年 | 37篇 |
1987年 | 32篇 |
1986年 | 30篇 |
1985年 | 17篇 |
1984年 | 23篇 |
1983年 | 20篇 |
1982年 | 17篇 |
1981年 | 22篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1978年 | 9篇 |
1977年 | 16篇 |
1976年 | 10篇 |
1975年 | 15篇 |
1973年 | 6篇 |
排序方式: 共有4896条查询结果,搜索用时 15 毫秒
41.
Morphological studies have shown that macrophages and microglia undergo
apoptosis in the central nervous system (CNS) in acute experimental
autoimmune encephalomyelitis (EAE) in the Lewis rat. To assess the relative
levels of macrophage and microglial apoptosis, and the molecular mechanisms
involved in this process, we used three-colour flow cytometry to identify
CD45lowCD11b/c+ microglial cells and CD45highCD11b/c+ macrophages in the
inflammatory cells isolated from the spinal cords of Lewis rats 13 days
after immunization with myelin basic protein (MBP) and complete Freund's
adjuvant. Simultaneously, we analyzed the DNA content of these cell
populations to assess the proportions of cells undergoing apoptosis and in
different stages of the cell cycle or examined their expression of three
apoptosis- regulating proteins, i.e. Fas (CD95), Fas ligand (FasL) and
Bcl-2. Microglia were highly vulnerable to apoptosis and were
over-represented in the apoptotic population. Macrophages were less
susceptible to apoptosis than microglia and underwent mitosis more
frequently than microglia. The different susceptibilities of microglia and
macrophages to apoptosis did not appear to be due to variations in Fas,
FasL or Bcl- 2 expression, as the proportions of microglia and macrophages
expressing these proteins were similar, and were relatively high.
Furthermore, in contrast to T cell apoptosis, apoptosis of
microglia/macrophages did not occur more frequently in cells expressing Fas
or FasL, or less frequently in cells expressing Bcl-2. These results
indicate that the apoptosis of microglia and CNS macrophages in EAE is not
mediated through the Fas pathway, and that Bcl-2 expression does not
protect them from apoptosis. Expression of FasL by macrophages and
microglia may contribute to the pathogenesis and immunoregulation of EAE
through interactions with Fas+ oligodendrocytes and Fas+ T cells. The high
level of microglial apoptosis in EAE indicates that microglial apoptosis
may be an important homeostatic mechanism for controlling the number of
microglia in the CNS following microglial activation and proliferation.
相似文献
42.
Coagulase-Negative Staphylococci: Comparison of Phenotypic and Genotypic Oxacillin Susceptibility Tests and Evaluation of the Agar Screening Test by Using Different Concentrations of Oxacillin 下载免费PDF全文
43.
Maria do Carmo Debur Juliano Bordignon Claudia Nunes Duarte dos Santos Luine Rosele Vidal Meri Bordignon Nogueira Sérgio Monteiro de Almeida Sonia Mara Raboni 《Journal of clinical virology》2007,39(1):59-62
BACKGROUND: Human metapneumovirus (hMPV) has been described as an etiologic agent of acute respiratory infections (ARI), mainly in pediatric patients. Viral isolation is difficult and has low sensitivity, and consequently RT-PCR assays are currently used for detection. OBJECTIVES: Detect hMPV in ARI in hospitalized children in Southern Brazil; standardize a RT-PCR for routine hMPV diagnosis; validate a positive control for molecular tests; and perform phylogenetics analyses. STUDY DESIGN: Nasopharyngeal aspirates (NPA) from 156 hospitalized children were studied. A conserved region of the nucleoprotein gene was cloned, characterized and used to standardize an RT-PCR assay. Phylogenetic analyses were performed. Clinical data were obtained from medical records. RESULTS: hMPV was detected in 6.4% of the samples. Dyspnea and wheezing were frequently reported symptoms and the most common diagnoses were bronchiolitis, acute respiratory insufficiency or laryngotracheobronchitis. Nucleotide sequence alignment revealed 97.7% identity with genotype A1 of hMPV. The detection limit of hMPV genomes by RT-PCR in clinical samples was 180 copies/microL. CONCLUSION: This is the first report of the detection and genetic characterization of hMPV infections in children with lower ARI in Southern Brazil. 相似文献
44.
Jernimo P. Martins Lucia C. Silva Matheus S. Nunes Gabriel Rübensam Jarbas R. Oliveira Rodrigo B. M. Silva Maria M. Campos 《Nutrients》2021,13(4)
Dry extracts from the Eurasian plants, Ajuga turkestanica, Eurycoma longifolia, and Urtica dioica have been used as anabolic supplements, despite the limited scientific data on these effects. To assess their actions on early sarcopenia signs, male and female castrated mice were supplemented with lyophilized extracts of the three plants, isolated or in association (named TLU), and submitted to resistance exercise. Ovariectomy (OVX) led to body weight increase and non-high-density cholesterol (HDL) cholesterol elevation, which had been restored by exercise plus U. dioica extract, or by exercise and TLU, respectively. Orchiectomy (ORX) caused skeletal muscle weight loss, accompanied by increased adiposity, being the latter parameter reduced by exercise plus E. longifolia or U. dioica extracts. General physical activity was improved by exercise plus herbal extracts in either OVX or ORX animals. Exercise combined with TLU improved resistance to fatigue in OVX animals, though A. turkestanica enhanced the grip strength in ORX mice. E. longifolia or TLU also reduced the ladder climbing time in ORX mice. Resistance exercise plus herbal extracts partly altered gastrocnemius fiber size frequencies in OVX or ORX mice. We provide novel data that tested ergogenic extracts, when combined with resistance exercise, improved early sarcopenia alterations in castrated male and female mice. 相似文献
45.
Ralf Berger Jurandir Marcondes Ribas Filho Osvaldo Malafaia Paulo Afonso Nunes Nassif Eduardo Nascimento Silva Alfredo Benjamin Duarte da Silva Milka Takejima Marcelo Augusto de Souza Pedro Henrique de Paula Mrio Rodrigues Montemor Netto Lucia de Noronha 《Acta cirúrgica brasileira / Sociedade Brasileira para Desenvolvimento Pesquisa em Cirurgia》2021,36(5)
46.
47.
E Hollander E Nunes C M DeCaria F M Quitkin T Cooper S Wager D F Klein 《Psychiatry research》1990,33(2):161-169
Ten male patients with chronic cocaine abuse received a single dose of the dopamine agonist apomorphine. Self-ratings of cocaine craving, depression, and anxiety decreased in response to apomorphine. Neuroendocrine response was consistent with central dopaminergic stimulation. Patients in the "craving" phase of the cocaine abuse cycle differed in behavioral but not neuroendocrine response to apomorphine from patients in the "crash" phase. Decrease in cocaine craving correlated with decrease in plasma homovanillic acid (pHVA). Total cocaine consumption correlated negatively with baseline prolactin and pHVA levels and inversely with peak change in prolactin following apomorphine. Patients had blunted neuroendocrine response to apomorphine in comparison to historical normal controls. Implications for the "dopamine" hypothesis of cocaine abuse are discussed. 相似文献
48.
Two thousand consecutive children have been evaluated for suspected heart disease in a 27-month period. The main reasons for referral were: murmur (70%), precordial pain (9.5%), suspicion of arrhythmia (8.5%) and breathless (5%). Five hundred and six (25%) cases did not complete the investigation and the results were not computed. A final diagnosis was obtained based on the reason for referral and the main conclusions were: 1) a high incidence of normality was found: murmur (83%), pain (98%), arrhythmia (97%) and breathless (94%); 2) heart disease is unlikely when other referral reasons were analyzed; 3) 14% of the children were considered abnormal and the necessity of therapeutic procedures was 0.8%. A pediatric cardiology outpatient clinic in a public setting seems to be justifiable in the region, due to the high current demand. 相似文献
49.
The authors report on a 45-day-old boy with a congenital intramedullary tumor with clinical manifestations since birth. Neurologic examination disclosed severe bilateral lower-limb hypotonia and diplegia, with exacerbated deep tendon reflexes and clonus associated with severe pain at manipulation. Further evaluation of this patient included screening for infections, computed tomographic scan, myelography, and somatosensory evoked potentials. The definite diagnosis was a solid holocord astrocytoma. This report discusses a rare disorder in the neonatal period and makes other medical practitioners aware of this diagnosis. Previously published literature is also reviewed. 相似文献
50.