全文获取类型
收费全文 | 2255篇 |
免费 | 150篇 |
国内免费 | 58篇 |
专业分类
耳鼻咽喉 | 22篇 |
儿科学 | 1篇 |
基础医学 | 356篇 |
口腔科学 | 220篇 |
临床医学 | 427篇 |
内科学 | 38篇 |
皮肤病学 | 10篇 |
神经病学 | 768篇 |
特种医学 | 66篇 |
外科学 | 114篇 |
综合类 | 242篇 |
现状与发展 | 1篇 |
预防医学 | 9篇 |
眼科学 | 30篇 |
药学 | 88篇 |
中国医学 | 56篇 |
肿瘤学 | 15篇 |
出版年
2024年 | 8篇 |
2023年 | 24篇 |
2022年 | 49篇 |
2021年 | 57篇 |
2020年 | 59篇 |
2019年 | 53篇 |
2018年 | 50篇 |
2017年 | 54篇 |
2016年 | 73篇 |
2015年 | 48篇 |
2014年 | 99篇 |
2013年 | 102篇 |
2012年 | 99篇 |
2011年 | 105篇 |
2010年 | 109篇 |
2009年 | 104篇 |
2008年 | 104篇 |
2007年 | 102篇 |
2006年 | 108篇 |
2005年 | 82篇 |
2004年 | 58篇 |
2003年 | 66篇 |
2002年 | 54篇 |
2001年 | 55篇 |
2000年 | 41篇 |
1999年 | 41篇 |
1998年 | 52篇 |
1997年 | 62篇 |
1996年 | 41篇 |
1995年 | 43篇 |
1994年 | 32篇 |
1993年 | 32篇 |
1992年 | 31篇 |
1991年 | 28篇 |
1990年 | 21篇 |
1989年 | 32篇 |
1988年 | 19篇 |
1987年 | 18篇 |
1986年 | 47篇 |
1985年 | 54篇 |
1984年 | 40篇 |
1983年 | 31篇 |
1982年 | 32篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1976年 | 4篇 |
1974年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有2463条查询结果,搜索用时 15 毫秒
11.
12.
目的采用电刺激大鼠上矢状窦(SSS)区硬脑膜,观察颈上交感神经节(SCG)摘除术前后在延髓和上颈段三叉神经脊束核一氧化氮合酶(NOS)阳性神经元数目的变化,以探讨交感神经系统在血管源性头痛(如偏头痛)涉及的伤害觉信息传递中的作用。方法以雄性SD大鼠(体重为220~250g)为实验对象,行颈上交感神经节摘除术后再手术暴露其SSS,然后电刺激SSS区硬脑膜,应用免疫组织化学染色技术,观察延髓和上颈段三叉神经脊束核NOS表达的变化。结果NOS免疫反应阳性神经元主要分布在三叉神经脊束核和上颈段脊髓的第Ⅰ、Ⅱ板层,双侧对称。假手术对照组、SCG摘除组每张切片的NOS阳性神经元数分别为150.2±10.3、223.0±11.6,SCG摘除组NOS阳性神经元数目较假手术对照组明显增加(P<0.05)。结论颈交感神经系统参与了头部血管源性疼痛(如偏头痛)中伤害性感觉信息导致的疼痛的产生、传导及调节过程。 相似文献
13.
14.
G. N. Kryzhanovskii E. E. Meizerov M. V. Koroleva V. K. Reshetnyak 《Bulletin of experimental biology and medicine》1997,124(3):862-866
No significant differences from the typical electroencephalogram were observed in patients with trigeminal neuropathy. In
patients with typical trigeminal neuralgia, the electroencephalogram variations were detected both in the changes of dominant
activity and in the appearance of individual pathological phenomena. The three-dimensional localization of pathological activity
generators points to the involvement of the median nonspecific brainstem structures into pathological process evoked by trigeminal
neuralgia.
Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 9, pp. 275–279, September, 1997 相似文献
15.
Retrogradely transported fluorescent dyes (fast blue and diamidino-dihydrochloride yellow) were used to compare the distributions of trigeminofugal neurons that project to the superior colliculus and/or the thalamus in three rodent species. The objective was to determine what the projection and collateralization patterns of these trigeminofugal pathways are and whether they are similar among different species. In each anesthetized animal, one dye was injected into the superior colliculus and the other into the topographically congruent area of the thalamus. Counts of the numbers of yellow, blue, and double-labeled neurons were made throughout the trigeminal complex: principalis, pars oralis, pars interpolaris, and pars caudalis. Trigeminothalamic projections were similar in each of the rodent species studied. The densest concentration of retrogradely labeled neurons was in principalis, with substantially fewer neurons in pars interpolaris, and fewer still in pars oralis and pars caudalis. These neurons were generally small and tended to have round or fusiform somata. A common pattern was also noted among the three species for trigeminotectal neurons. Most trigeminotectal projections originated from neurons in pars interpolaris, somewhat fewer from pars oralis, and the fewest from principalis and pars caudalis. These neurons tended to be the largest in each subdivision and were often multipolar. Following paired injections of the tracers, double-labeled neurons were scattered throughout the sensory trigeminal complex and had morphologies characteristic of single-labeled trigeminotectal neurons. Although comparatively few double-labeled neurons were observed in any species, most of those seen were restricted to the ventrolateral portion of pars interpolaris, a position that corresponds to the representation of the vibrissae. These data indicate that, regardless of the rodent species, the vast majority of labeled trigeminal neurons project either to the superior colliculus or the thalamus, but not to both targets. This might be expected on the basis of the very different behavioral roles these structures play. On the other hand, a subpopulation of trigeminal neurons exists (mainly in pars interpolaris) that does project to both the superior colliculus and the thalamus, perhaps because both structures require some of the same somatosensory information to perform their behavioral functions. 相似文献
16.
Theodore A. Henderson Robert W. Rhoades Carol A. Bennett-Clarke Pat A. Osborne Eugene M. Johnson Mark F. Jacquin 《The Journal of comparative neurology》1993,336(2):243-260
Prior studies indicate that neonatal nerve injury kills many trigeminal (V) first- and second-order cells, and interrupts pattern formation in the brainstem and cerebral cortex. Yet it is not known whether effects upon cell survival and pattern formation are causally related. To determine whether axotomized V ganglion cells can be rescued by an exogenous trophic agent, rats received 5 mg/kg of nerve growth factor (NGF) prior to, and every day after, infraorbital nerve section on the day of birth until sacrifice on postnatal day (PND) 1, 3, 5, 7, or 14. Other animals received identical lesions without NGF. Ganglion cell numbers were significantly reduced by PNDl in pups not given NGF, while NGF-treated rats displayed no significant cell loss through PND7. However, NGF did not permanently rescue V neurons because ganglion cell numbers were reliably reduced by PND14. Cell numbers in V nucleus principalis were reduced by PNDl in pups not given NGF, while NGF-treated animals displayed no cell loss through PND14. NGF's rescue of second-order cells is probably an indirect effect of NGF actions upon V ganglion cells because, in other newborns, NGF failed to maintain principalis cells after direct lesion of the left V ganglion. To determine whether preventing cell death permits whisker-related pattern formation, other rats also received NGF prior to and after infraorbital nerve section at birth. After 3–14 days, patterns were assessed in the brainstem and cortex with cytochrome oxidase histochemistry and serotonin immunocytochemistry. Whisker-related patterns failed to develop as in cases not given NGF. These data indicate that communication with the periphery is necessary for the maintenance of central whisker-related patterns. They also suggest that V ganglion cells can be rescued, albeit temporarily, from rapid injury-induced death by NGF, thereby delaying injury-induced cell death in nucleus principalis. However, the mechanism(s) responsible for injury-induced pattern alterations in the developing V system remains to be elucidated. © 1993 Wiley-Liss, Inc. 相似文献
17.
The distribution and time course of gamma-aminobutyric acid (GABA) immunoreactivity was investigated in the cranium of the chick embryo from 2 to 16 days of incubation (E2-16). A fraction of nerve fibers transiently stains GABA-positive in all cranial motor nerves and in the vestibular nerve. Cranial motor nerves stain GABA-positive from E4 to E11, including neuromuscular junctions at E8-11; labeled fibers are most frequent in the motor trigeminal root (E6-9.5). Substantial GABA staining is present from E4 to E10 in a subpopulation (1-2%) of vestibular ganglion cells. Their peripheral processes are labeled in the vestibular endorgan, predominantly in the posterior crista. Some GABA-positive fibers are present in the olfactory nerve (after E5) and in the optic nerve (after E9.5); their immunoreactivity persists throughout the period investigated. Transient GABA immunoreactivity follows "pioneer" fiber outgrowth and coincides with the formation of early synaptic contacts. GABA-containing neurons may change their neuronal phenotype (loss of GABA expression) or they may be eliminated by embryological cell death. Periods of cell death were determined in cranial ganglia and motor nuclei by aggregations of pycnotic cells in the same embryonic material. The periods of embryonic cell death partly coincide with transient GABA immunoreactivity. The function(s) of transient GABA expression is unknown. Some lines of evidence suggest that GABA has neurotrophic functions in developing cranial nerves or their target tissue. In the developing neuromuscular junction, GABA may be involved in the regulation of acetylcholine receptors. 相似文献
18.
19.
与眶下神经相关的初级传入纤维终末的溃变、非突触部位胞吐及突触联系 总被引:1,自引:0,他引:1
切断眶下神经的各组大鼠存活2~30天后分别杀死,于其三叉神经尾侧脊束核胶状质亚核内观察了一级传入纤维轴突终末的溃变过程.非突触部位胞吐及突触联系.结果发现:(1)眶下神经的跨节溃变、以突触小泡聚集、融合、空泡形成为主要特征,无微丝增生现象:(2)部分溃变终末内的线粒体明显肿胀变暗.呈球形改变:(3)大致密核心小泡的溃变时间远滞后于突触小泡.两者并不同步进行;(4)轴突终未在溃变过程中,其内的大致密核心小泡仍然进行非突触部位胞吐;(5)溃变纤维终末于胶状质内分别形成轴一树、轴一体、轴一轴三种类型的突触、并参与了突触复合体的形成. 相似文献
20.
The distribution of cells of origin of ascending and descending internuclear connections in the trigeminal sensory nuclei was studied by the retrograde horseradish peroxidase technique in the cat. The termination of collaterals of these ascending axons was also studied by the anterograde transport of horseradish peroxidase. Following injections of horseradish peroxidase into the ventral part of the principal sensory nucleus and the adjacent reticular formation many small neurons were labeled ipsilaterally in the whole area of the caudal portion of the nucleus interpolaris and in laminae III and IV of the nucleus caudalis. Labeled neurons were also found in laminae I and V. Injections limited to either nucleus oralis, the ventral part of the principal sensory nucleus and the medial parabrachial nucleus labeled similar types of neurons in the above regions with a topographic relationship; neurons in the dorsal part of the nuclei caudalis and interpolaris project, dorsally, to rostral portions of the trigeminal sensory nuclei while those in the ventral part of the nuclei caudalis and interpolaris project ventrally. Anterograde labeling of axons arising from the nucleus caudalis demonstrates that the axons ascend in the intranuclear bundles and the adjacent reticular formation, and give off collaterals to the nuclei interpolaris and oralis, and the ventral part of the principal sensory nucleus. Injections limited to the nucleus caudalis labeled small neurons in the rostral portion of the nucleus oralis and the caudal portion of the nucleus interpolaris. The present study suggests that these ascending and descending internuclear connections of the trigeminal sensory nuclei may modulate transmission of afferent inputs to various projection sites, such as thalamus, superior colliculus, cerebellum and spinal cord. 相似文献