全文获取类型
收费全文 | 354篇 |
免费 | 93篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 2篇 |
妇产科学 | 1篇 |
基础医学 | 70篇 |
口腔科学 | 10篇 |
临床医学 | 44篇 |
内科学 | 166篇 |
皮肤病学 | 12篇 |
神经病学 | 29篇 |
特种医学 | 32篇 |
外国民族医学 | 7篇 |
外科学 | 15篇 |
综合类 | 4篇 |
预防医学 | 25篇 |
眼科学 | 1篇 |
药学 | 22篇 |
肿瘤学 | 7篇 |
出版年
2016年 | 6篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 8篇 |
2012年 | 12篇 |
2011年 | 14篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 10篇 |
2007年 | 9篇 |
2006年 | 19篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 9篇 |
2002年 | 13篇 |
2001年 | 8篇 |
2000年 | 15篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1996年 | 6篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 11篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1983年 | 13篇 |
1982年 | 8篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 15篇 |
1976年 | 7篇 |
1975年 | 11篇 |
1974年 | 7篇 |
1973年 | 9篇 |
1972年 | 6篇 |
1970年 | 4篇 |
1968年 | 4篇 |
1967年 | 6篇 |
1966年 | 3篇 |
1965年 | 6篇 |
1964年 | 4篇 |
1963年 | 6篇 |
1962年 | 4篇 |
1960年 | 3篇 |
排序方式: 共有448条查询结果,搜索用时 15 毫秒
71.
72.
Weissmann N Voswinckel R Tadic A Hardebusch T Ghofrani HA Schermuly RT Seeger W Grimminger F 《American journal of respiratory cell and molecular biology》2000,23(2):222-227
Hypoxic pulmonary vasoconstriction (HPV) is essential for matching lung perfusion with ventilation, thus optimizing pulmonary gas exchange. Preceding studies provided evidence for a role of both nitric oxide (NO) and superoxide/ H(2)O(2) formation in this vasoregulatory mechanism. Both agents might be operative via stimulation of guanylate cyclase with formation of the vasodilatory cyclic guanosine monophosphate (cGMP), the loss of which under conditions of hypoxia contributes to HPV. This view is challenged by the recent suggestion of increased rather than decreased superoxide/H(2)O(2) formation in hypoxia. We addressed the role of NO-dependent versus NO-independent guanylate cyclase activity in hypoxic and pharmacologically evoked vasoconstriction in perfused rabbit lungs. Two inhibitors of soluble guanylate cyclase, LY83583 (2 to 16 microM) and methylene blue (20 to 60 microM), increased baseline pulmonary artery pressure under normoxic conditions and markedly amplified the vasoconstrictor response to both hypoxia and the stable thromboxane analogue U46619. Under conditions of preblocked lung NO synthesis (N(G)-mono-methyl-L-arginine), however, additional guanylate cyclase inhibition further enhanced the vasoconstrictor response to U46619 but did not influence the strength of HPV. The selective phosphodiesterase V inhibitor Zaprinast (1 to 10 microM), used for prolongation of the cGMP half-life, reduced the hypoxia-induced pressor response to a larger extent than the pressor response to U46619. This difference was lost under conditions of preblocked NO synthesis. Equilibration of the lung perfusate with molecular NO suppressed the HPV more potently than the U46619-induced vasoconstrictor response. We conclude that NO-dependent guanylate cyclase activity has an important role in attenuating the vasoconstrictor response to alveolar hypoxia in rabbit lungs. In contrast, no evidence was obtained for a role of NO-independent cGMP formation in HPV. In this feature, HPV differs from that elicited by the thromboxane analogue U46619. 相似文献
73.
74.
Extracellular pH changes may constitute significant signals for neuronal communication. During synaptic transmission, changes in pH in the synaptic cleft take place. Its role in the regulation of presynaptic Ca2+ currents through multivesicular release in ribbon‐type synapses is a proven phenomenon. In recent years, protons have been recognized as neurotransmitters that participate in neuronal communication in synapses of several regions of the CNS such as amygdala, nucleus accumbens, and brainstem. Protons are released by nerve stimulation and activate postsynaptic acid‐sensing ion channels (ASICs). Several types of ASIC channels are expressed in the peripheral and central nervous system. The influx of Ca2+ through some subtypes of ASICs, as a result of synaptic transmission, agrees with the participation of ASICs in synaptic plasticity. Pharmacological and genetical inhibition of ASIC1a results in alterations in learning, memory, and phenomena like fear and cocaine‐seeking behavior. The recognition of endogenous molecules, such as arachidonic acid, cytokines, histamine, spermine, lactate, and neuropeptides, capable of inhibiting or potentiating ASICs suggests the existence of mechanisms of synaptic modulation that have not yet been fully identified and that could be tuned by new emerging pharmacological compounds with potential therapeutic benefits. 相似文献
75.
76.
Ankit Mittal Anne S. Raber Ulrich F. Schaefer Sebastian Weissmann Thomas Ebensen Kai Schulze Carlos A. Guzmán Claus-Michael Lehr Steffi Hansen 《Vaccine》2013
Transfollicular vaccination aims to reach the peri-follicular antigen presenting cells without impairing the stratum corneum (SC) barrier. This would be an optimal vaccination strategy under critical hygienic conditions. Nanoparticles (NPs) are the ideal vehicles for transfollicular delivery of vaccines as they are able to (i) penetrate deeper into the hair follicles than molecules in solution, (ii) can help to stabilize protein based antigen and (iii) improve and modulate the immune response. 相似文献
77.
Aya Mohr Sasson Abraham Tsur Anat Kalter Alina Weissmann Brenner Liat Gindes 《The journal of maternal-fetal & neonatal medicine》2016,29(8):1318-1321
Objective: Evaluate physiologic factors associated with reduced maternal perception of fetal movements (RFM).Methods: A historical cohort study of all women (years 2011–2013, n?=?399) that visited the maternal emergency room (ER) (gestational age 24?+?0–42?+?0) due to RFM (group A), that was compared to a control group consisted from women with normal perception of fetal movements (group B). Groups were compared for maternal characteristics (age, gravity, parity, BMI), gestational age, placental location, gestational age at birth and fetal outcomes (birth-weight and Apgar scores).Results: In a multivariate regression analysis, including maternal age, height, weight, BMI, gestational age on admission to ER, gravity, parity and placental location, only two variables remained significantly associated with RFM – nulliparity (OR?=?2.28, p?=?0.001) and anterior placenta (OR?=?1.44, p?=?0.034). Group A was not associated with lower Apgar scores (1 and 5-min, p?=?0.40 and 0.57, respectively) or low birth-weight (p?=?0.76), nor was it associated with prematurity (p?=?0.41), low (<7) 5-min Apgar score, fetal death or neonatal death.Conclusions: Reduced fetal movements are associated with anterior placenta and nulliparity. 相似文献
78.
79.
80.