全文获取类型
收费全文 | 105723篇 |
免费 | 10480篇 |
国内免费 | 3142篇 |
专业分类
耳鼻咽喉 | 850篇 |
儿科学 | 1214篇 |
妇产科学 | 1008篇 |
基础医学 | 12297篇 |
口腔科学 | 3680篇 |
临床医学 | 10853篇 |
内科学 | 11083篇 |
皮肤病学 | 1313篇 |
神经病学 | 6666篇 |
特种医学 | 3631篇 |
外国民族医学 | 11篇 |
外科学 | 7767篇 |
综合类 | 15473篇 |
现状与发展 | 8篇 |
一般理论 | 3篇 |
预防医学 | 17553篇 |
眼科学 | 1233篇 |
药学 | 14000篇 |
116篇 | |
中国医学 | 5898篇 |
肿瘤学 | 4688篇 |
出版年
2024年 | 399篇 |
2023年 | 1975篇 |
2022年 | 4139篇 |
2021年 | 5094篇 |
2020年 | 4945篇 |
2019年 | 4282篇 |
2018年 | 3912篇 |
2017年 | 4173篇 |
2016年 | 4222篇 |
2015年 | 4077篇 |
2014年 | 7297篇 |
2013年 | 7790篇 |
2012年 | 7076篇 |
2011年 | 7422篇 |
2010年 | 5510篇 |
2009年 | 5137篇 |
2008年 | 4934篇 |
2007年 | 4932篇 |
2006年 | 4172篇 |
2005年 | 3650篇 |
2004年 | 3001篇 |
2003年 | 2748篇 |
2002年 | 2158篇 |
2001年 | 2033篇 |
2000年 | 1603篇 |
1999年 | 1404篇 |
1998年 | 1321篇 |
1997年 | 1188篇 |
1996年 | 1027篇 |
1995年 | 937篇 |
1994年 | 915篇 |
1993年 | 702篇 |
1992年 | 667篇 |
1991年 | 561篇 |
1990年 | 477篇 |
1989年 | 491篇 |
1988年 | 433篇 |
1987年 | 379篇 |
1986年 | 309篇 |
1985年 | 381篇 |
1984年 | 299篇 |
1983年 | 178篇 |
1982年 | 206篇 |
1981年 | 160篇 |
1980年 | 157篇 |
1979年 | 121篇 |
1978年 | 82篇 |
1977年 | 56篇 |
1976年 | 75篇 |
1974年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
时间治疗学的计量研究 总被引:2,自引:0,他引:2
以《中国生物医学文献光盘数据库》(CBM)、《中文生物医学期刊文献数据库》(CMCC)和 OVID为数据源 ,全面检索时间治疗学的文献信息 ,利用文献管理软件 Pro Cite5辅助以手工方法对获取的信息进行管理和计量分析 ,以纳入文献的年代、期刊、著者、主题、国别和机构分布等科学和文献计量学指标全面揭示和评价时间治疗学的研究现状和发展趋势。研究结果显示 :时间治疗学的中文文献 91篇 ,分布于 73种期刊中 ,主题分布于中医学、心血管系统疾病、肿瘤、哮喘、消化性溃疡、糖尿病和时间治疗学总论等方面 ;同时纳入来自 35个国家和地区的有关外文文献 4 80篇 ,主要数据来源于 EMBASE和 MEDL INE,分布于 2 85种期刊中 ,收录时间治疗学文献 5篇以上的期刊有 14种 ,著者包括 12位 ,收录时间治疗学文献前 11名的机构分别为鲍尔勃罗斯医院、德州大学、康涅狄格州医学院、日本自治医学院、明尼苏达大学等。有关时间治疗学的研究 ,国内尚处于临床应用初期 ,国外已经形成核心著者、核心期刊和核心研究机构 ,主要分布在欧美等发达国家 ,已经在多个方面取得成绩。 相似文献
992.
Marius Schwabenland Henrike Salié Jovan Tanevski Saskia Killmer Marilyn Salvat Lago Alexandra Emilia Schlaak Lena Mayer Jakob Matschke Klaus Püschel Antonia Fitzek Benjamin Ondruschka Henrik E. Mei Tobias Boettler Christoph Neumann-Haefelin Maike Hofmann Angele Breithaupt Nafiye Genc Christine Stadelmann Bertram Bengsch 《Immunity》2021,54(7):1594-1610.e11
993.
994.
995.
S. LeVay T. Voigt 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1990,82(1):67-76
Summary The stability of visual perception despite eye movements suggests the existence, in the visual system, of neural elements able to recognize whether a movement of an image occurring in a particular part of the retina is the consequence of an actual movement that occurred in the visual field, or self-induced by an ocular movement while the object was still in the field of view. Recordings from single neurons in area V3A of awake macaque monkeys were made to check the existence of such a type of neurons (called real-motion cells; see Galletti et al. 1984, 1988) in this prestriate area of the visual cortex. A total of 119 neurons were recorded from area V3A. They were highly sensitive to the orientation of the visual stimuli, being on average more sensitive than V1 and V2 neurons. Almost all of them were sensitive to a large range of velocities of stimulus movement and about one half to the direction of it. In order to assess whether they gave different responses to the movement of a stimulus and to that of its retinal image alone (self-induced by an eye movement while the stimulus was still), a comparison was made between neuronal responses obtained when a moving stimulus swept a stationary receptive field (during steady fixation) and when a moving receptive field swept a stationary stimulus (during tracking eye movement). The receptive field stimulation at retinal level was physically the same in both cases, but only in the first was there actual movement of the visual stimulus. Control trials, where the monkeys performed tracking eye movements without any intentional receptive field stimulation, were also carried out. For a number of neurons, the test was repeated in darkness and against a textured visual background. Eighty-seven neurons were fully studied to assess whether they were real-motion cells. About 48% of them (42/87) showed significant differences between responses to stimulus versus eye movement. The great majority of these cells (36/42) were real-motion cells, in that they showed a weaker response to visual stimulation during tracking than to the actual stimulus movement during steady fixation. On average, the reduction in visual response during eye movement was 64.0 ± 15.7% (SD). Data obtained with a uniform visual background, together with those obtained in darkness and with textured background, indicate that real-motion cells receive an eye-motion input, either retinal or extraretinal in nature, probably acting presynaptically on the cell's visual input. In some cases, both retinal and extraretinal eye-motion inputs converge on the same real-motion cell. No correlation was observed between the real-motion behaviour and the sensitivity to either orientation or direction of movement of the visual stimulus used to activate the receptive field, nor with the retinotopic location of the receptive field. We suggest that the visual system uses real-motion cells in order to distinguish real from self-induced movements of retinal images, hence to recognize the actual movement in the visual field. Based on psychophysical data, the hypothesis has been advanced of an internal representation of the field of view, stable despite eye movement (cf. MacKay 1973). The real-motion cells may be neural elements of this network and we suggest that the visual system uses the output of this network to properly interpret the large number of sensory changes resulting from exploratory eye movements in a stable visual world. 相似文献
996.
Katsuhiro Komase Takeshi Haga Yasuhiro Yoshikawa Takeshi A. Sato Kazuya Yamanouchi 《Virus genes》1990,4(2):163-172
The full-length cDNA corresponding to the mRNA for the hemagglutinin (H) protein of the Yamagata-1 strain of the subacute sclerosing panencephalitis (SSPE) virus was cloned and the nucleotide sequence was determined. The mRNA corresponding to the H protein was composed of 1952 nucleotides and contained a single large open reading frame, which encoded 620 amino acids with a predicted molecular weight of 69,723. This cDNA clone expressed the H protein in Cos 7 cells, and the transfected cells showed hemadsorption. The nucleotide and amino-acid sequence homology with the Edmonston strain of MV were 98.0% and 96.6%, respectively. The deduced amino acid sequence had a single hydrophobic domain near the N-terminus that was long enough to serve as an anchor in the membrane. Five potential glycosylation sites were found on the H protein at identical positions as in the H protein of MV. Cysteine and proline were located at almost identical positions as those of the H protein of MV. In addition, monoclonal antibody study revealed that three epitopes, including the domains that were involved in the biological activities of the H protein of MV, were conserved on the Yamagata-1 strain. These results suggested that the H protein of the Yamagata-1 strain of defective SSPE virus is structurally and functionally similar to that of the Edmonston strain of MV. 相似文献
997.
M. Neri G. B. Migliori A. Spanevello D. Berra E. Nicolin C. V. Landoni L. Ballardini M. Sommaruga P. Zanon 《Allergy》1996,51(5):313-319
The aims of the present study were as follows:
- 1). to evaluate the medical outcomes of two treatment and educational asthma programs
- 2). to determine by cost-analysis both cost and economic outcome of the programs
- 3). to perform a cost-benefit analysis (determining the net cost-benefit) and a cost-effectiveness analysis (determining the cost per unit of effect and the incremental cost-effectiveness ratio) from the perspective of health program policy makers (HPP; indirect costs, i.e., loss of productivity, excluded) and of society as a whole (Saw; all costs included).
998.
Robert N. Holdefer Barry L. Jacobs 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1994,100(3):444-452
Neurons in the locus coeruleus (LC) encode information related to behavioral state in a tonic pattern of firing and information
related to the occurrence of a sensory stimulus in a phasic pattern of firing. The effects of phasic stimulation of the LC
(6 pulses at 30 Hz), designed to approximate its physiological activation by sensory stimuli, were studied in the lateral
geniculate nucleus (LGN) of anesthetized rats. Phasic stimulation of the LC significantly increased neuronal firing in the
LGN with a mean latency 320 ms from onset of stimulation. Receiver operating characteristic analyses on a trial-by-trial basis
showed that phasic LC stimulation can result in a highly discriminable signal in the LGN. This increased neuronal firing rate
in the LGN was specific for the site of stimulation and was reduced by the norepinephrine synthesis inhibitor αmethyl-p-tyrosine
and by intravenous WB-4101 (α1-receptor antagonist). Neurons in the LGN have a singlespike firing mode when sensory information is faithfully relayed from
retina to cortex and a burst-firing mode when the transfer of this information is degraded. Phasic LC stimulation reduced
burst firing (2–5 ms interspike intervals, ISIs) at low frequencies ( ≤4 Hz) in the LGN, and for some neurons there was an
absolute decrease in burst-like ISIs after LC stimulation, despite an increase in mean firing rate. 相似文献
999.
A. P. Somlyo A. V. Somlyo T. Kitazawa M. Bond H. Shuman D. Kowarski 《Annals of biomedical engineering》1983,11(6):579-588
Filamentous myosin is present in both relaxed (myosin light chains unphosphorylated) and contracted (light chains phosphorylated)
vascular smooth muscle. The organization of myosin and actin filaments and the insertion of the latter on cytoplasmic and
plasma membrane bound dense bodies is consistent with a mini sarcomere-like organization and a sliding filament mechanism
of contraction in smooth muscle.
Mitochondria are high capacity, low affinity Ca stores in smooth muscle. They do not play a role in the regulation of cytoplasmic
Ca2+ at physiological levels.
The localization and Ca content of the junctional sarcoplasmatic reticulum (SR) is consistent with this organelle being the
major intracellular source of activator Ca released by excitatory transmitters.
Repeated contractions in the absence of extracellular Ca2+ (thought to represent recycling of intracellular activator Ca2+) can be demonstrated if the excitatory agent is not allowed to remain in contact with the smooth muscle throughout relaxation;
the demonstration of “recycling” is facilitated if the efflux of cellular Ca2+ is blocked.
The rise in total cytoplasmic calcium measured with electron probe analysis during a maintained (30 min) contracture in rabbit
portal-anterior mesenteric vein smooth muscle (∼0.9 mmol/kg dry cytoplasm) is greater than the amount of Ca that could be
bound to calmodulin. 相似文献
1000.
Genetic Conservation of Hemagglutinin Gene of H9 Influenza Virus in Chicken Population in Mainland China 总被引:1,自引:0,他引:1
The hemagglutinin (HA) genes of 12 H9N2 influenza virus strains isolated from chickens in Mainland China during the period 1995–2002 were genetically analyzed. All the isolates possessed the same amino acid motif -R-S-S-R/G-L- at the cleavage site of HA. Except for the conserved amino acids, as is the case in the other avian influenza viruses, located in the receptor binding site, all of the 12 isolates possessed N at amino acid position 183; A, T, or V at position 190; K at position 137, whereas the representative strains of the other lineage (except Dk/HK/Y280/97-like lineage) virus of H9N2 viruses had H, E, and R at these positions respectively. These could be considered as the partial molecular markers of the H9 viruses isolated from chickens in Mainland China. Phylogenetic analyses showed HA genes of these isolates belonged to that of A/duck/Hong Kong/Y280/97-like virus lineage. No A/quail/Hong Kong/Gl/97-like virus was found in chicken, population since the outbreak of H9N2 influenza in Mainland China in 1992. The available evidence indicates that HA genes of H9 influenza virus circulating in Mainland China during the past years were well conserved. 相似文献