全文获取类型
收费全文 | 163041篇 |
免费 | 6757篇 |
国内免费 | 55篇 |
出版年
2021年 | 1078篇 |
2020年 | 1002篇 |
2019年 | 958篇 |
2018年 | 3159篇 |
2017年 | 3048篇 |
2016年 | 5300篇 |
2015年 | 9049篇 |
2014年 | 8800篇 |
2013年 | 9857篇 |
2012年 | 9908篇 |
2011年 | 6981篇 |
2010年 | 5219篇 |
2009年 | 4344篇 |
2008年 | 4571篇 |
2007年 | 4304篇 |
2006年 | 4294篇 |
2005年 | 9536篇 |
2004年 | 8323篇 |
2003年 | 6217篇 |
2002年 | 3654篇 |
2001年 | 3102篇 |
2000年 | 2246篇 |
1999年 | 2881篇 |
1998年 | 1015篇 |
1992年 | 2778篇 |
1991年 | 2793篇 |
1990年 | 2831篇 |
1989年 | 2823篇 |
1988年 | 2624篇 |
1987年 | 2506篇 |
1986年 | 2263篇 |
1985年 | 2389篇 |
1984年 | 1697篇 |
1983年 | 1360篇 |
1982年 | 914篇 |
1981年 | 829篇 |
1979年 | 1711篇 |
1978年 | 1227篇 |
1977年 | 1079篇 |
1976年 | 1042篇 |
1975年 | 1429篇 |
1974年 | 1591篇 |
1973年 | 1574篇 |
1972年 | 1461篇 |
1971年 | 1388篇 |
1970年 | 1313篇 |
1969年 | 1390篇 |
1968年 | 1279篇 |
1967年 | 1194篇 |
1966年 | 1026篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
991.
Application of electroacupuncture (EAP) of the segmental points to patients with vertebrogenic algesic syndromes decreased amplitude of N150 and P240 waves recorded from vertex to painful electrocutaneous stimulation in the region innervated by an affected root. As distinct from EAP of segmental point auricular EAP not only decreased the amplitude of late components of evoked potentials (EP), but also increased it, direction of EP changes depending on the character of sensitivity disorders. It is suggested that effect of EAP-evoked EP changes in patients with hypalgesia is determined by two oppositively acting factors: by a decrease of nociceptive afferent impulsation intensity as a result of the antinociceptive system activation and by an increase of the afferent impulsation intensity due to recovery of function of central terminals in primary sensory neurons. 相似文献
992.
A V Chumachenko S K Aznaur'ian V A Trotsevich V I Danile?ko 《Fiziologicheski? zhurnal》1989,35(1):62-65
A method of variation pulsometry was used to determine the vegetative homeostasis state in 20 children aged from 4 to 14. Normotonic type of the cardiac rhythm regulation was observed in a group of children aged 4-5. In children aged 12-14 the effect of sympathetic area of the vegetative nervous system decreased while the effect of the parasympathetic one increased. The tension index, effect of the humoral regulation channel and the degree of cardiac rhythm control centralization decreased. 相似文献
993.
The method of tissue embedding in melamine resin was applied to rat skeletal muscle. This method does not require tissue dehydration with organic solvents; only aqueous solutions are used. Electron micrographs of muscles embedded in melamine differ from those embedded in the conventional epoxy resin. In melamine-embedded muscles the actin and myosin filaments appear larger in diameter and subunits can be recognized in cross-sectioned myosin filaments. Within the Z-line, the characteristic patterns described for muscles embedded in epoxy resin are not visible; the spaces between the actin filaments are filled with electron-dense material. This suggests that the Z-line is more compact than could be concluded from epoxy resin-embedded muscle specimens. The M-line appears to be different from what is observed in epoxy-embedded muscle. The membranes appear as several clearly delineated layers. Dehydration rather than the action of the organic solvents per se is the main reason for the differences in the structure of the contractile apparatus between melamine- and epoxy-embedded muscles. 相似文献
994.
J R López L E Brice?o G Cordovez V Sánchez N Linares 《General physiology and biophysics》1989,8(2):91-98
Carnitine is required for the transport of activated long chain fatty acids through the mitochondrial inner membrane. We measured the intracellular free calcium concentration [( Ca2+]i) by means of a calcium selective microelectrode in skeletal muscle biopsies obtained from nine patients in which myopathic carnitine deficiency (MCD) was diagnosed, and from six subjects with no evidence of neuromuscular disease. Intact intercostal muscle bundles were dissected and then split for electron microscopic studies and electrophysiological measurements. The [Ca2+]i in muscle fibers from MCD patients was 0.46 +/- 0.02 mumol.l-1 (mean +/- SEM) and 0.10 +/- 0.01 mumol.l-1 in control subjects. At the electron microscopic level, the predominant abnormality was the presence of lipid vacuoles between the myofibrils. These results show that in patients with myopathic carnitine deficiency there is a significant increase in the resting myoplasmic calcium concentration which might be related to a malfunction of some mechanisms responsible for the homeostasis of intracellular calcium. 相似文献
995.
High-molecular DNA from chicken erythrocytes interacts with 1,2-dipalmitoylphosphatidylcholine in unilamellar liposomes, both in the presence and absence of Mg2+ ions. This interaction results in a phase separation in liposome membranes. The new phase induced by DNA and Mg2+ has a higher gel-liquid crystal phase transition temperature as measured by microcalorimetry. In the liquid crystalline state, the 16- and 5-doxyl stearic acid spin labels indicate changed local bilayer properties at the label position in the new phase. 相似文献
996.
The effect of free radicals generated by PMS was studied for membrane damage in the presence of different ions in the erythrocyte model. The degree of membrane damage depended on the quality of ionic composition in the incubation medium. We supposed that the degree of membrane damage depends on the average life and concentration and/or reactivity of the free radicals generated. For control of this supposition free radicals were generated by PMS in the presence of Sodium-di-thionite in isosmotic, waterly systems with different ionic composition. At different time intervals the concentration of free radicals was measured by the ESR method. It seams that concentration of radicals depends on the qualitative composition of ionic milieu. The increase of the average life of free radicals generated by PMS is accompanied by decrease in their reactivity. This is reflected by a moderate membrane damage. 相似文献
997.
O Pálmai 《Acta physiologica Hungarica》1989,73(2-3):379-381
The emergence of the artificial intelligence (AI) in computer technology and its application in the medical field enables the researchers to carry out such intelligent activities like image processing, medical reasoning systems, clinical decision supporting and natural language understanding, etc. A gastroenterological expert system application is briefly demonstrated in this paper. Similar expert systems can be seen to be useful in the research of gastrointestinal cytoprotection, including the plan of different compounds with cytoprotective effect, experimental and clinical medical research. 相似文献
998.
L Nagy G Nagy I Rácz L Simon I Solt I Patty F Tárnok G Mózsik T Jávor 《Acta physiologica Hungarica》1989,73(2-3):331-339
TISACID (a new, modern Hungarian Al-containing antacid) with a high acid-neutralizing capacity (greater than 26.8 mmol/g) also enhances gastric mucosal defense mechanisms (prostaglandin-dependent gastroprotection). A simple-blind, prospective, randomized, parallel multicentre clinical trial has been performed on both the clinical efficacy and possible side effects of TISACID monotherapy (Al-Mg-hydroxy-carbonate) on informed patients suffering from active duodenal ulcers. The study groups were as follows: Group "A": 3 g/day of TISACID (acid-neutralizing capacity = 78 mmol, n = 85), Group "B": 6 g/day of TISACID (acid-neutralizing capacity = 156 mmol, n = 88), Group "C": 12 g/day of TISACID (acid-neutralizing capacity = 312 mmol, n = 68), Group "D": (as control): (1.0 g/day cimetidine (HISTODIL, RGH, Budapest, n = 91). The total number of patients: 332. It was found that: 1. The new Hungarian antacid compound (both tablet and suspension) can essentially accelerate the healing rate of duodenal ulcers. 2. The cumulative healing rate of ulcers and the decrease of complaints can be achieved equally by relatively low doses of TISACID monotherapy and cimetidine alone. 3. There were no differences between the clinical potency and side-effects of TISACID tablet and suspension. 相似文献
999.
The aim of this study was to elaborate a simple in vitro model for rapid and quantitative measurement of free radical effects. Free radical generating characteristics of PMS were measured in the case of red blood cell (RBC) membrane. The mechanism of free radical action was investigated in MgCl2, CaCl2, BaCl2 and in Verapamil HCl medium. The most important result of the investigations is as follows: Membrane damage of RBC provoked by the mechanism of free radical generation of PMS is proportional to the intracellular K+-efflux and to the extracellular Na+-influx. The PMS dependent K+-efflux in a NaCl containing medium in the presence of CaCl2 increases significantly, while it remains unchanged in MgCl2 medium. The PMS dependent K+-efflux and Na+-influx were considerably decreased by Verapamil HCl in NaCl containing solution. We have come to the conclusion that new, non-selective pores are formed in the membrane. The measure of the damage increases in the presence of Ca2+ions and decreases in the medium containing Verapamil HCl. 相似文献
1000.
The authors investigated the effects of (+) cyanidanol-3-(Catergen) in vitro on the activities of rat brain plasma membrane and microsomal Na+-K+-ATP-ase and Mg++-ATP-ase, in the presence and absence of ascorbic acid. Due to lipid peroxidation induced by low concentration of ascorbid acid, activity of both ATP-ase decreased. (+) cyanidanol-3 proved to be an effective antioxidant in this system. It inhibited the decrease of ATP-ase activity which occurred as a result of lipid peroxidation promoted by ascorbic acid. 相似文献