全文获取类型
收费全文 | 8336篇 |
免费 | 405篇 |
国内免费 | 97篇 |
专业分类
耳鼻咽喉 | 64篇 |
儿科学 | 212篇 |
妇产科学 | 176篇 |
基础医学 | 990篇 |
口腔科学 | 152篇 |
临床医学 | 602篇 |
内科学 | 2367篇 |
皮肤病学 | 249篇 |
神经病学 | 793篇 |
特种医学 | 314篇 |
外科学 | 1353篇 |
综合类 | 24篇 |
预防医学 | 393篇 |
眼科学 | 75篇 |
药学 | 455篇 |
中国医学 | 8篇 |
肿瘤学 | 611篇 |
出版年
2023年 | 75篇 |
2022年 | 164篇 |
2021年 | 265篇 |
2020年 | 147篇 |
2019年 | 185篇 |
2018年 | 232篇 |
2017年 | 168篇 |
2016年 | 222篇 |
2015年 | 246篇 |
2014年 | 308篇 |
2013年 | 412篇 |
2012年 | 589篇 |
2011年 | 625篇 |
2010年 | 356篇 |
2009年 | 328篇 |
2008年 | 520篇 |
2007年 | 507篇 |
2006年 | 502篇 |
2005年 | 510篇 |
2004年 | 478篇 |
2003年 | 430篇 |
2002年 | 352篇 |
2001年 | 90篇 |
2000年 | 75篇 |
1999年 | 93篇 |
1998年 | 70篇 |
1997年 | 68篇 |
1996年 | 52篇 |
1995年 | 50篇 |
1994年 | 41篇 |
1993年 | 36篇 |
1992年 | 34篇 |
1991年 | 43篇 |
1990年 | 43篇 |
1989年 | 41篇 |
1988年 | 38篇 |
1987年 | 41篇 |
1986年 | 31篇 |
1985年 | 39篇 |
1984年 | 29篇 |
1983年 | 25篇 |
1982年 | 24篇 |
1981年 | 17篇 |
1980年 | 14篇 |
1979年 | 22篇 |
1977年 | 20篇 |
1976年 | 12篇 |
1975年 | 24篇 |
1974年 | 14篇 |
1972年 | 14篇 |
排序方式: 共有8838条查询结果,搜索用时 10 毫秒
51.
Clinical,immunological, and molecular analysis in a large cohort of patients with X-linked agammaglobulinemia: an Italian multicenter study 总被引:5,自引:0,他引:5
Plebani A Soresina A Rondelli R Amato GM Azzari C Cardinale F Cazzola G Consolini R De Mattia D Dell'Erba G Duse M Fiorini M Martino S Martire B Masi M Monafo V Moschese V Notarangelo LD Orlandi P Panei P Pession A Pietrogrande MC Pignata C Quinti I Ragno V Rossi P Sciotto A Stabile A;Italian Pediatric Group for XLA-AIEOP 《Clinical immunology (Orlando, Fla.)》2002,104(3):221-230
A questionnaire-based retrospective clinical and immunological survey was conducted in 73 males with a definite diagnosis of X-linked agammaglobulinemia based on BTK sequence analysis. Forty-four were sporadic and 29 familial cases. At December 2000, the patients' ages ranged from 2 to 33 years; mean age at diagnosis and mean duration of follow-up were 3.5 and 10 years respectively. After the mid-1980s all but 2 were on intravenous immunoglobulin (IVIG) substitution therapy, with residual IgG >500 mg/dl in 94% of the patients at the time of enrollment. Respiratory infections were the most frequent manifestation both prior to diagnosis and over follow-up. Chronic lung disease (CLD) was present in 24 patients, in 15 already at diagnosis and in 9 more by 2000. The cumulative risk to present at diagnosis with CLD increased from 0.17 to 0.40 and 0.78 when the diagnosis was made at the ages of 5, 10, and 15 years respectively. For the 9 patients who developed CLD during follow-up, the duration of follow-up, rather than age at diagnosis; previous administration of intramuscular immunoglobulin; and residual IgG levels had a significant effect on the development of CLD. Chronic sinusitis was present in 35 patients (48%), in 15 already at diagnosis and in 20 by 2000. Sistemic infections such as sepsis and meningitis/meningoencephalitis decreased over follow-up, probably due to optimal protection provided by high circulating IgG levels reached with IVIG. 相似文献
52.
Monica Rossi Enzo Ricci Luca Colantoni Giuliana Galluzzi Roberto Frusciante Pietro A Tonali Luciano Felicetti 《BMC medical genetics》2007,8(1):8
Background
The homologous 4q and 10q subtelomeric regions include two distinctive polymorphic arrays of 3.3 kb repeats, named D4Z4. An additional BlnI restriction site on the 10q-type sequence allows to distinguish the chromosomal origin of the repeats. Reduction in the number of D4Z4 repeats below a threshold of 10 at the 4q locus is tightly linked to Facioscapulohumeral Muscular Dystrophy (FSHD), while similar contractions at 10q locus, are not pathogenic. Sequence variations due to the presence of BlnI-sensitive repeats (10q-type) on chromosome 4 or viceversa of BlnI-resistant repeats (4q-type) on chromosome 10 are observed in both alleles. 相似文献53.
Vignozzi L Vannelli GB Morelli A Mancina R Marini M Ferruzzi P Crescioli C Luconi M Donati S Fisher AD Baldi E Filippi S Forti G Maggi M 《Molecular human reproduction》2005,11(2):99-106
Although abnormalities of the male external genitalia (MEG) are a relatively common problem, little is known concerning the molecular mechanisms that finely regulate penile development. We report here the expression of the oxytocin receptor (OTR) gene by real-time RT-PCR in human fetal tissues (11th-12th week of gestation), including the MEG. The developing penis expressed a very high level of OTR mRNA, only a half log(10) unit lower than fetal central nervous system, used as a positive control. The OTR protein is also highly expressed (western, immunohistochemistry and binding studies) and immunolocalized both in the mesenchymal body and in the surrounding blood capillaries, which will later constitute penile trabeculae and sinusoids. Binding studies using [125I]oxytocin antagonist ([125I]OTA) in cultured human fetal penile smooth muscle cells (hfPSMC) revealed the presence of specific OTR with a high capacity and affinity for oxytocin (OT) and for OTA. Increasing concentrations of OT dose-dependently induced intracellular Ca2+ mobilization. Furthermore, OTR mediated an increase in the proliferation and the migration of hfPSMC. In conclusion, we demonstrate that in the developing human MEG, OTR is highly expressed and might be involved in coordinating timely and appropriate proliferation and migration of the penile cells. Thus, OTR might represent an additional target for investigating human fetal MEG organogenesis. 相似文献
54.
Vincenzo Di Lazzaro Fabio Pilato Michele Dileone Pietro A. Tonali Ulf Ziemann 《The Journal of physiology》2005,569(1):315-323
Peripheral nerve inputs have an inhibitory effect on motor cortex excitability at short intervals (short-latency afferent inhibition, SAI). This can be tested by coupling electrical stimulation of peripheral nerve with transcranial magnetic stimulation (TMS) of the motor cortex. SAI is reduced by the anticholinergic drug scopolamine, and in patients with Alzheimer's disease. Therefore, it is possible that SAI is a marker of central cholinergic activity important for memory function. The benzodiazepine lorazepam also reduces SAI. Since benzodiazepines impair memory formation, but do not do so uniformly, with a maximum amnesic effect after lorazepam but less or no effect after diazepam, we were interested in testing in this non-behavioural study to what extent the effects of lorazepam and diazepam on circuits involved in SAI could be dissociated. In addition, and for control, we tested the effects of lorazepam and diazepam on short-interval intracortical inhibition (SICI), a motor cortical inhibition mediated through the GABAA receptor. Lorazepam markedly reduced SAI, whereas diazepam slightly increased it. In contrast, both benzodiazepines uniformly increased SICI. Our findings demonstrate opposite effects of lorazepam and diazepam on SAI, an inhibition modulated by central cholinergic activity, but the same effects on SICI, a marker of neurotransmission through the GABAA receptor. This dissociation suggests, for the first time, that TMS measures of cortical inhibition provide the opportunity to segregate differences of benzodiazepine action in human central nervous system circuits. 相似文献
55.
Carlo Delfini Anna Rosa Garbuglia Elena Alfani Antonino Di Caro Pietro Sette Arrigo Benedetto 《Journal of medical virology》1993,41(2):114-119
Several reports show that the prevalence of HBV (hepatitis B virus) carriers in HIV (human immunodeficiency virus) infected populations is significantly higher than in HIV seronegative individuals, independent of the risk group for HIV, that is, homosexuals or drug abusers. In this context, evaluation of the simultaneous presence of HBV and HIV in PBMCs (peripheral blood monuclear cells) is of particular interest for at least 2 reasons: 1) the possible reciprocal influence of the 2 viruses when they infect the same cell; 2) the possibility that HIV-iduced hematological disorders could indirectly influence the settling of HBV in blood cell populations. We report data on the frequency of PCR positivity for HBV DNA in PBMCs from 62 HIV infected patients, rigorously selected by risk group, that is, intravenous use of heroin for at least 3 years and syringe promiscuity. Sixtyseven HIV negative individuals who never used any drug formed the control group. The analysis of the cases positive for HBV DNA in PBMCs showed that 1) the overall prevalence of PCR positivity found in HIV infected patients was significantly lower than that registered in the control group; 2) PCR positivity among the subjects who were HBsAg negative and anti-HBV positive was extremely low in the HIV infected patients (3.7%) but quite frequent in the HIV negative subjects (37.0%). The results support the hypothesis that, unlike the HIV negative individuals, our HIV infected patients exhibited HBV DNA in PBMCS almost exclusively when they presented with active HBV replication. 相似文献
56.
Selmi C Ichiki Y Invernizzi P Podda M Gershwin ME 《Clinical reviews in allergy & immunology》2005,28(2):73-81
Primary biliary cirrhosis (PBC) is a chronic cholestatic disease characterized by a striking predominance in female patients
(with most cases diagnosed between ages 40 and 60 yr) as well as serum auto-antibodies to mitochondrial antigens, elevated
serum immunoglobulin M, progressive destruction of intrahepatic bile ducts, and, ultimately, liver cirrhosis and failure (1). The precise mechanisms leading to selective destruction of biliary epithelial cells lining intrahepatic bile ducts are
still unknown, although numerous immunomediated pathways have been proposed. Genetic background appears to be important in
determining susceptibility to the disease (2), but no clear association with alleles in the major histocompatibility complex has been identified. Molecular mimicry either
by infections (3) or xenobiotics (4) has been proposed to be capable of breaking tolerance in genetically predisposed individuals, thus leading to onset of PBC.
This article describes and discusses the available data regarding the immunomediated pathogenesis of PBC (with particular
attention to auto-antibodies and autoreactive T-cells) and presents the recent evidence indicating a role for either xenobiotic
chemicals or novel infectious agents in the induction of the disease. 相似文献
57.
58.
59.
DNA cross-link-dependent RAD50/MRE11/NBS1 subnuclear assembly requires the Fanconi anemia C protein 总被引:7,自引:0,他引:7
Fanconi anemia (FA) is a cancer-predisposition syndrome characterized by hypersensitivity to interstrand-cross-link (ICL) inducers. FA hypersensitivity to ICL has been correlated with alterations in homologous recombination, non-homologous end-joining, telomere maintenance, DNA-damage assessment and checkpoint regulation, processes in which the components of the RAD50/MRE11/NBS1 (RMN) complex are involved. To better characterize the mechanisms by which ICL are processed in human cells and to gain insight into their toxicity in FA, we examined (i). the RMN complex assembling in response to the ICL inducers mitomycin C (MMC) and photoactivated 8-methoxypsoralen and (ii). the proficiency of FA cells to perform RMN activation in response to ICL inducers. We show here that ICL activates the assembly of the RMN proteins into subnuclear foci, and that their formation proceeds independently of ICL incision, a step mainly dependent on XP-F/ERCC1 heterodimer activity. Interestingly, FA cells were unable to form RMN foci in response to either ICL inducer. Analysis by pulsed-field gel electrophoresis and single-cell gel electrophoresis of MMC-treated cells showed that FA cells from complementation group C (FA-C cells, defective in the FANCC gene) form double-strand breaks and unhook MMC-induced ICL similarly to FANCC wild-type cells. These observations imply that the absence of RMN assembly in FA-C cells is not simply due to the absence of DNA ends produced as intermediates of ICL processing, and indicates a direct role for FANCC in RMN focus assembly in response to ICL inducers. Moreover, we show that the formation of foci, including BRCA1 and/or RAD51 proteins, is significantly delayed in FA cells. These alterations in the assembly of DNA-repair proteins in FA provide an interpretation for the DNA-damage processing anomalies observed in FA cells and for the genetic instability and the cancer predisposition of the syndrome. 相似文献
60.
Biolistic (biological ballistic) and protoplast-mediated procedures were compared as methods for transforming strains of Gliocladium virens and Trichoderma harzianum. For biolistic transformation, conidia were bombarded using a helium-driven biolistic device to accelerate M5 tungsten particles coated with plasmid or genomic DNA. DNA from either source contained a bacterial hygromycin B resistance gene (hygB) as a dominant selectable marker. The same sources of DNA were also used to transform protoplasts using a standard polyethylene glycol-CaCl2 protoplast fusion protocol. Hygromycin B-resistant (HygBR) transformants were recovered from all strains, methods, and DNA sources except for genomic DNA used with the protoplast method. The biolistic procedure was technically simpler, and increased transformation frequency and genetic stability in the progeny as compared with the protoplast-mediated transformation. Southern analysis of homokaryotic HygBR progenies showed that the transforming sequences were integrated into the genome of the recipient strains, and apparently were methylated. This is the first study presenting detailed results on biolistic transformation of a filamentous fungus. 相似文献