全文获取类型
收费全文 | 2239767篇 |
免费 | 163484篇 |
国内免费 | 7807篇 |
专业分类
耳鼻咽喉 | 31942篇 |
儿科学 | 73419篇 |
妇产科学 | 59518篇 |
基础医学 | 313794篇 |
口腔科学 | 60478篇 |
临床医学 | 200381篇 |
内科学 | 431585篇 |
皮肤病学 | 49429篇 |
神经病学 | 170370篇 |
特种医学 | 89115篇 |
外国民族医学 | 888篇 |
外科学 | 337952篇 |
综合类 | 61117篇 |
现状与发展 | 20篇 |
一般理论 | 627篇 |
预防医学 | 165741篇 |
眼科学 | 50681篇 |
药学 | 174749篇 |
121篇 | |
中国医学 | 10510篇 |
肿瘤学 | 128621篇 |
出版年
2021年 | 17846篇 |
2019年 | 17606篇 |
2018年 | 24534篇 |
2017年 | 19660篇 |
2016年 | 21266篇 |
2015年 | 24768篇 |
2014年 | 33940篇 |
2013年 | 49175篇 |
2012年 | 67350篇 |
2011年 | 71411篇 |
2010年 | 43958篇 |
2009年 | 40832篇 |
2008年 | 65763篇 |
2007年 | 69934篇 |
2006年 | 70397篇 |
2005年 | 67511篇 |
2004年 | 64577篇 |
2003年 | 62362篇 |
2002年 | 60441篇 |
2001年 | 113064篇 |
2000年 | 116548篇 |
1999年 | 97888篇 |
1998年 | 25624篇 |
1997年 | 23007篇 |
1996年 | 23237篇 |
1995年 | 21854篇 |
1994年 | 20322篇 |
1993年 | 18975篇 |
1992年 | 75364篇 |
1991年 | 72957篇 |
1990年 | 71474篇 |
1989年 | 68416篇 |
1988年 | 62480篇 |
1987年 | 61128篇 |
1986年 | 57176篇 |
1985年 | 54449篇 |
1984年 | 40108篇 |
1983年 | 33751篇 |
1982年 | 19027篇 |
1979年 | 35781篇 |
1978年 | 24451篇 |
1977年 | 21241篇 |
1976年 | 19178篇 |
1975年 | 21257篇 |
1974年 | 24751篇 |
1973年 | 23831篇 |
1972年 | 22350篇 |
1971年 | 20587篇 |
1970年 | 19262篇 |
1969年 | 18047篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Thirty outpatients with panic disorder (PD) were treated at an anxiety clinic using a symptom-focused approach. Thirteen (43%) had no history of major depressive disorder (MDD), 12 (40%) had a history of secondary MDD, and 5 (17%) had history of primary MDD. The outcome was equally good in patients with no history of MDD (77% had good or excellent outcomes) and patients with a history of secondary MDD (83% had good or excellent outcomes). Patients with a history of primary MDD had the worst outcomes. These findings agree with earlier studies showing that secondary MDD does not adversely affect prognosis of patients presenting for treatment of PD. 相似文献
992.
993.
Afterpotential characteristics and firing patterns in maturing rat hippocampal CA1 neurones in in vitro slices. 总被引:2,自引:0,他引:2
The postnatal evolution of depolarizing after-potentials (DAPs) and after-hyperpolarizations (AHPs) was studied in rat CA1 hippocampal neurones (5-68 days of age) using in vitro slices. Results were pooled into 4 age groups: P5-9, P10-16, P17-24 and P26-68. In P5-9 cells, DAPs were seen as passive signals, with a time constant similar to the time constant of the membrane. The evolution of the DAP was characterized by a decrease in amplitude, an increase in duration and a change in contour. In P10-16 and P17-24 cells, the DAPs often had a plateau or a hump-like shape which increased the probability of firing and the occurrence of spike doublets. The firing pattern and bursting behaviour of P10-16 CA1 neurones differed from the pattern typical of the adult. P5-9 and P10-16 cells had post-burst AHPs with a smaller amplitude and a more prolonged early phase than at late stages of development. 相似文献
994.
P Sacerdote F Rubboli L Locatelli I Ciciliato P Mantegazza A E Panerai 《Journal of neuroimmunology》1991,32(1):35-41
The concentrations of beta-endorphin and cholecystokinin were measured in fresh resting peripheral mononuclear cells obtained from rats and human subjects in basal conditions and after different pharmacological treatments. Both in the human and the rat, beta-endorphin concentrations in mononuclear cells, increased after treatment with serotoninergic agonists, decreased after dopaminergic or GABAergic drugs, while the respective antagonists exerted the opposite effect. In vitro, serotoninergic and GABAergic compounds confirmed their roles in the modulation of beta-endorphin in mononuclear cells. Cholecystokinin was never affected by the pharmacological treatments. 相似文献
995.
996.
Basic fibroblast growth factor prevents thalamic degeneration after cortical infarction 总被引:10,自引:0,他引:10
K Yamada A Kinoshita E Kohmura T Sakaguchi J Taguchi K Kataoka T Hayakawa 《Journal of cerebral blood flow and metabolism》1991,11(3):472-478
In the focal infarction model of the rat middle cerebral artery (MCA), the thalamus of the occluded side becomes gradually atrophic, mainly because of retrograde degeneration. We determined whether basic fibroblast growth factor (bFGF) administered intracisternally could prevent this thalamic atrophy. We occluded the left MCA through a small cranial opening, and animals were then divided into two groups. One group received intracisternal injections of recombinant bFGF (1 microgram dissolved in 0.1 ml of saline with 2% rat serum) starting 1 day after occlusion and repeated once a week to a total dose of 4 micrograms by four injections. The other group received vehicle solution by the same schedule. The animals were perfused and fixed at 28 days after occlusion, and histological examination was made at the level of the caudoputamen and thalamus. In the bFGF-treated rats, the area of the posterior ventral thalamus of the occluded side was 93% of that of the contralateral side, i.e., significantly larger than in the normal saline-treated rats (75%, p less than 0.01). The infarction size was not statistically different in the two groups. Microscopic observation indicated that normal-saline-treated animals showed shrinkage and disappearance of thalamic neurons, whereas bFGF-treated groups showed preservation of thalamic neurons. Computerized analysis of the cell size substantiated this observation. To assess the effect of bFGF on astrocytes, bFGF or vehicle solution was injected into normal rats, and their histology was evaluated at 1, 2, and 4 weeks after injection. The bFGF-injected group showed a significant increase in glial fibrillary acidic protein-positive astrocytes in the brain tissue facing the ventriculocisternal system.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
997.
K. Dorovini-Zis A. P. Zis 《Journal of neural transmission (Vienna, Austria : 1996)》1991,84(1-2):75-84
Summary Autonomic innervation of the adrenal cortex has been demonstrated in several species. Detailed ultrastructural studies on the innervation of the zona fasciculata of the normal human adrenal cortex are lacking. We report herein our observations on the pattern of innervation of the cells of the zona fasciculata of the normal adult human cortex at both the light and electron microscope levels. Postganglionic unmyelinated fibers were observed to descend from a dense capsular meshwork and to be distributed as delicate branches among the columns of endocrine cells. Immunoperoxidase staining confirmed the presence of nerve fibers in the zona fasciculata in a distribution similar to that observed after staining with silver impregnation methods. Ultrastructural findings lent further support to these observations by the demonstration of bundles of unmyelinated fibers with focal enlargements containing terminal boutons with both clear and dense core vesicles in close approximation with the endocrine cells. 相似文献
998.
The involvement of excitatory amino acid (EAA) receptors in mediation of the toxic effects of cocaine was studied in male ICR mice. Cocaine HCl (90 mg/kg, IP) induced seizures in 95% and death within 24 h in 68% (n = 135) of the animals. There was a significant correlation (r = .54) between the time to onset of convulsions and the time to death in mice which died within 30 min of injection (n = 84). Pretreatment with selected EAA receptor antagonists 15 min prior to cocaine differentially blocked cocaine toxicity. Selective N-methyl-D-aspartic acid (NMDA) receptor antagonists (MK-801, dextrorphan, CPP) decreased both the incidence of seizures and mortality. A nonselective EAA antagonist, kynurenic acid, decreased lethality in doses which did not reduce convulsions. A similar action was observed following pretreatment with the selective kainic acid/AMPA receptor antagonist, GDEE. Antagonists at EAA receptors can provide significant protection against cocaine-induced toxicity. Moreover, the data provide evidence for the involvement of both NMDA and non-NMDA receptor subtypes in aspects of cocaine toxicity. 相似文献
999.
P F Rogers G A Head Y K Lungershausen P R Howe 《Journal of the autonomic nervous system》1991,34(1):9-16
The potential role of adrenaline, both circulating and in the central nervous system, in the maintenance of high blood pressure was examined in stroke-prone spontaneously hypertensive rats (SHRSP). alpha-Monofluoromethyldopa, a long-lasting inhibitor of dopa decarboxylase, was used to induce rapid depletion of central and peripheral catecholamine stores. Subsequent inhibition of phenylethanolamine-N-methyltransferase (PNMT) allowed the gradual restoration of dopamine and noradrenaline but not adrenaline, resulting in a greater relative depletion of adrenaline. Adrenaline was almost totally depleted in the circulation and peripheral tissues. The resting level of blood pressure, however, was unaffected, excepting after administration of a vasopressin (AVP) antagonist. Moreover, there was no reduction in the magnitude of acute pressor responses to electrical stimulation of the rostral ventrolateral medulla oblongata (C1 area), despite extensive loss of adrenaline from the brainstem and spinal cord. The results suggest that adrenaline contributes to the resting level of blood pressure but that its loss can be offset by the pressor activity of AVP. Thus neither central nor peripheral adrenaline stores appear to be essential for the maintenance of hypertension or for centrally-evoked vasoconstriction in adult SHRSP. 相似文献
1000.
D D Cochrane K J Poskitt M G Norman 《The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques》1991,18(2):181-195
Cerebral dysgenesis encompasses varied disorders of brain development. Based on the understanding of these conditions provided by histopathologists, embryologists, radiologists and developmental pediatricians, surgeons are able to appropriately assist in the care of these patients. The surgeon can offer assessment of the ventriculomegaly that commonly accompanies cerebral dysgenesis in addition to providing methods to control hydrocephalus, to reconstruct cranial and facial malformations and to remove dysfunctional tissue. For most patients, surgical intervention is only one of the many factors that determine developmental prognosis. Based on the foundation built by other specialists, this review discusses cerebral dysgenesis from the perspective of historical and current surgical interventions. 相似文献