全文获取类型
收费全文 | 6590篇 |
免费 | 403篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 84篇 |
儿科学 | 153篇 |
妇产科学 | 186篇 |
基础医学 | 995篇 |
口腔科学 | 664篇 |
临床医学 | 530篇 |
内科学 | 1333篇 |
皮肤病学 | 112篇 |
神经病学 | 611篇 |
特种医学 | 143篇 |
外科学 | 662篇 |
综合类 | 33篇 |
预防医学 | 625篇 |
眼科学 | 66篇 |
药学 | 376篇 |
中国医学 | 59篇 |
肿瘤学 | 383篇 |
出版年
2023年 | 47篇 |
2022年 | 109篇 |
2021年 | 207篇 |
2020年 | 161篇 |
2019年 | 236篇 |
2018年 | 256篇 |
2017年 | 164篇 |
2016年 | 209篇 |
2015年 | 248篇 |
2014年 | 298篇 |
2013年 | 359篇 |
2012年 | 550篇 |
2011年 | 538篇 |
2010年 | 274篇 |
2009年 | 226篇 |
2008年 | 352篇 |
2007年 | 411篇 |
2006年 | 329篇 |
2005年 | 283篇 |
2004年 | 274篇 |
2003年 | 269篇 |
2002年 | 205篇 |
2001年 | 152篇 |
2000年 | 126篇 |
1999年 | 117篇 |
1998年 | 44篇 |
1997年 | 26篇 |
1996年 | 16篇 |
1995年 | 31篇 |
1994年 | 19篇 |
1993年 | 15篇 |
1992年 | 44篇 |
1991年 | 50篇 |
1990年 | 41篇 |
1989年 | 32篇 |
1988年 | 26篇 |
1987年 | 19篇 |
1986年 | 17篇 |
1985年 | 18篇 |
1984年 | 17篇 |
1983年 | 10篇 |
1980年 | 14篇 |
1979年 | 16篇 |
1978年 | 10篇 |
1974年 | 15篇 |
1973年 | 14篇 |
1971年 | 13篇 |
1970年 | 13篇 |
1967年 | 10篇 |
1966年 | 14篇 |
排序方式: 共有7015条查询结果,搜索用时 31 毫秒
11.
Rodica Pop-Busui Jiang Lu Neuza Lopes Teresa L. Z. Jones and the BARI D Investigators 《Journal of the peripheral nervous system : JPNS》2009,14(1):1-13
Abstract We evaluated the associations between glycemic therapies and prevalence of diabetic peripheral neuropathy (DPN) at baseline among participants in the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial on medical and revascularization therapies for coronary artery disease (CAD) and on insulin-sensitizing vs. insulin-providing treatments for diabetes. A total of 2,368 patients with type 2 diabetes and CAD was evaluated. DPN was defined as clinical examination score >2 using the Michigan Neuropathy Screening Instrument (MNSI). DPN odds ratios across different groups of glycemic therapy were evaluated by multiple logistic regression adjusted for multiple covariates including age, sex, hemoglobin A1c (HbA1c), and diabetes duration. Fifty-one percent of BARI 2D subjects with valid baseline characteristics and MNSI scores had DPN. After adjusting for all variables, use of insulin was significantly associated with DPN (OR = 1.57, 95% CI: 1.15–2.13). Patients on sulfonylurea (SU) or combination of SU/metformin (Met)/thiazolidinediones (TZD) had marginally higher rates of DPN than the Met/TZD group. This cross-sectional study in a cohort of patients with type 2 diabetes and CAD showed association of insulin use with higher DPN prevalence, independent of disease duration, glycemic control, and other characteristics. The causality between a glycemic control strategy and DPN cannot be evaluated in this cross-sectional study, but continued assessment of DPN and randomized therapies in BARI 2D trial may provide further explanations on the development of DPN. 相似文献
12.
13.
A C Meneses M A Lopes A Rocha M C Fatureto G P Lopes E R Lopes E Chapadeiro 《Arquivos de gastroenterologia》1989,26(1-2):13-16
This is a review of 4.690 necropsies and 24.209 surgical pathology specimens describing the association between megacolon chagasic and malignant tumors of the large bowel. The prevalence of malignant tumors of the large bowel was not higher in megacolon. 相似文献
14.
A C Da Rosa B Kemp T Paiva F H Lopes da Silva H A Kamphuisen 《Electroencephalography and clinical neurophysiology》1991,78(1):71-79
A model of sleep phasic events such as vertex waves, K complexes, delta waves and sleep spindles is proposed. It consists of feedback loops that are driven by white noise (simulating tonic delta and sigma activity) and by isolated random impulses, simulating vertex waves or K complexes, depending on the background tonic activity. A model-based method for the detection of sleep phasic events was implemented in a personal computer. Its performance was investigated using simulated and real whole-night EEG signals. The method was able to detect K complexes and vertex waves in a reliable way in spite of their variable shapes and in the presence of a variety of background activities. The detector appears to have superior performance to those so far reported in the literature. The performance of the detector was also compared to that of an electroencephalographer using normal sleep EEG records of 8 h duration from 6 subjects. The performance was satisfactory both in terms of accuracy and reliability. The problem of detecting K complexes in stages 3 and 4 of sleep is discussed. 相似文献
15.
16.
17.
Coeli M. B. Lopes Tibor Rohács Gábor Czirják Tamás Balla Péter Enyedi Diomedes E. Logothetis 《The Journal of physiology》2005,564(1):117-129
Two-pore (2-P) domain potassium channels are implicated in the control of the resting membrane potential, hormonal secretion, and the amplitude, frequency and duration of the action potential. These channels are strongly regulated by hormones and neurotransmitters. Little is known, however, about the mechanism underlying their regulation. Here we show that phosphatidylinositol 4,5-bisphosphate (PIP2 ) gating underlies several aspects of 2-P channel regulation. Our results demonstrate that all four 2-P channels tested, TASK1, TASK3, TREK1 and TRAAK are activated by PIP2 . We show that mechanical stimulation may promote PIP2 activation of TRAAK channels. For TREK1, TASK1 and TASK3 channels, PIP2 hydrolysis underlies inhibition by several agonists. The kinetics of inhibition by the PIP2 scavenger polylysine, and the inhibition by the phosphatidylinositol 4-kinase inhibitor wortmannin correlated with the level of agonist-induced inhibition. This finding suggests that the strength of channel PIP2 interactions determines the extent of PLC-induced inhibition. Finally, we show that PIP2 hydrolysis modulates voltage dependence of TREK1 channels and the unrelated voltage-dependent KCNQ1 channels. Our results suggest that PIP2 is a common gating molecule for K+ channel families despite their distinct structures and physiological properties. 相似文献
18.
C. M. A. Pennartz R. F. Ameerun H. J. Groenewegen F. H. Lopes da Silva 《The European journal of neuroscience》1993,5(2):107-117
Extra- and intracellular recordings in slices were used to examine what types of synaptic plasticity can be found in the core of the nucleus accumbens, and how these forms of plasticity may be modulated by dopamine. Stimulus electrodes were placed at the rostral border of the nucleus accumbens in order to excite primarily infralimbic and prelimbic afferents, as was confirmed by injections of the retrograde tracer fluoro-gold. In extracellular recordings, tetanization induced long-term potentiation (LTP) of the population spike in 20 out of 53 slices. The presynaptic compound action potential did not change following LTP induction. For the intracellularly recorded excitatory postsynaptic potential, three types of synaptic plasticity were noted: long-term potentiation (16 out of 54 cells), decremental potentiation (eight cells) and long-term depression (LTD; six cells). No correlation was found between the occurrence of potentiation or depression and various parameters of the tetanic depolarization (e.g. peak voltage, integral under the curve). The N -methyl- d -aspartate receptor antagonist d (–)-2-amino-5-phosphonopentanoic acid (50 μM; d -AP5) reduced, but did not completely prevent, the induction of LTP. The incidence of LTD was not markedly affected by d -AP5. No difference in LTP was found when comparing slices bathed in dopamine (10 μM) and controls. Likewise, slices treated with a mixture of the D1 receptor antagonist Sch 23390 (1 μM) and the D2 antagonist S (–)-sulpiride (1 μM) generated a similar amount of LTP as controls. In conclusion, both LTP and LTD can be induced in a key structure of the limbic-innervated basal ganglia. LTP in the nucleus accumbens strongly depends on N -methyl- d -aspartate receptor activity, but is not significantly affected by dopamine. 相似文献
19.
20.
Immunological and echocardiographic evaluation of decellularized versus cryopreserved allografts during the Ross operation. 总被引:3,自引:0,他引:3
Francisco Diniz Affonso da Costa Pascal Maria Dohmen Daniele Duarte Cristina von Glenn Sérgio Veiga Lopes Hermínio Haggi Filho Marise Brenner Affonso da Costa Wolfgang Konertz 《European journal of cardio-thoracic surgery》2005,27(4):572-578
OBJECTIVE: Compare the immunological and echocardiographic data of decellularized versus cryopreserved allografts used for RVOT reconstruction during Ross operation. METHODS: From 16/01/03 thru 07/10/03, 20 Ross operations were performed using decellularized (n=11) or cryopreserved (n=9) allografts. Echocardiography was done at discharge, 1, 3, 6 and 12 months and annually thereafter. Samples for determination of antibodies against HLA class I and II were obtained preoperatively and at days 5, 10, 30, 90 and 180 postoperatively. These samples were tested by the ELISA method in LAT-M dishes (unspecific) for identification of circulating antibodies and the results expressed as mean sample values (Is=DO/cutoff). If positive, LAT-E (specific) was performed and PRA levels determined. RESULTS: There was no mortality. Cryopreserved allografts showed marked Is values elevations for class I and II antibodies which started at the first month and remained elevated up to 6 months. In contrast, of the patients receiving decellularized allografts, seven remained negative, two patients had only marginal elevation of class I antibodies and two patients showed abnormal elevations of PRA levels. This response happened earlier than in the cryopreserved group, starting on the 5th postoperative day and has returned to baseline levels in one case. Echocardiography showed mild, but significant, elevation of gradients in cryopreserved valves but none in the decellularized. CONCLUSIONS: Decellularized allografts had normal function up to 18 months and showed important reduction of the immunogenic response when compared to cryopreserved valves. 相似文献