全文获取类型
收费全文 | 9457篇 |
免费 | 748篇 |
国内免费 | 281篇 |
专业分类
耳鼻咽喉 | 1075篇 |
儿科学 | 93篇 |
妇产科学 | 22篇 |
基础医学 | 1155篇 |
口腔科学 | 97篇 |
临床医学 | 786篇 |
内科学 | 666篇 |
皮肤病学 | 37篇 |
神经病学 | 1371篇 |
特种医学 | 334篇 |
外国民族医学 | 2篇 |
外科学 | 1982篇 |
综合类 | 1359篇 |
现状与发展 | 1篇 |
预防医学 | 134篇 |
眼科学 | 292篇 |
药学 | 438篇 |
6篇 | |
中国医学 | 104篇 |
肿瘤学 | 532篇 |
出版年
2024年 | 19篇 |
2023年 | 129篇 |
2022年 | 203篇 |
2021年 | 269篇 |
2020年 | 285篇 |
2019年 | 287篇 |
2018年 | 263篇 |
2017年 | 298篇 |
2016年 | 334篇 |
2015年 | 305篇 |
2014年 | 522篇 |
2013年 | 531篇 |
2012年 | 492篇 |
2011年 | 473篇 |
2010年 | 376篇 |
2009年 | 379篇 |
2008年 | 397篇 |
2007年 | 421篇 |
2006年 | 459篇 |
2005年 | 371篇 |
2004年 | 302篇 |
2003年 | 302篇 |
2002年 | 265篇 |
2001年 | 223篇 |
2000年 | 196篇 |
1999年 | 178篇 |
1998年 | 214篇 |
1997年 | 161篇 |
1996年 | 138篇 |
1995年 | 160篇 |
1994年 | 136篇 |
1993年 | 114篇 |
1992年 | 100篇 |
1991年 | 97篇 |
1990年 | 93篇 |
1989年 | 88篇 |
1988年 | 71篇 |
1987年 | 80篇 |
1986年 | 77篇 |
1985年 | 94篇 |
1984年 | 108篇 |
1983年 | 102篇 |
1982年 | 102篇 |
1981年 | 74篇 |
1980年 | 63篇 |
1979年 | 34篇 |
1978年 | 23篇 |
1977年 | 19篇 |
1976年 | 21篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
53.
The aortic nipple, a small “pseudotumor” adjacent to the aortic arch, is the left superior intercostal vein. In our series
of 40 patients it was demonstrated in six; all had a right upper thoracic mass and four had a superior vena caval syndrome.
Coronal magnetic resonance, images (MRI) of the thorax were superior to all other imaging methods in demonstrating the nipple.
It is concluded that in patients with masses in the right upper chest, coronal MR chest examinations are valuable in demonstrating
an aortic nipple, a sign of impending present superior vena caval or innominate, vein obstruction. 相似文献
54.
Y. Kannan R. H. Stead C. H. Goldsmith J. Bienenstock 《Journal of neuroscience research》1994,37(3):374-383
Induction of neurite outgrowth from superior cervical ganglia (SCG) by rat lymphoid tissues was studied using a tissue culture model. Neonatal rat SCG were cultured with 6–12-week-old rat thymus, spleen, or mesenteric lymph node (MLN) explants in a Martrigel layer, in defined culture medium without exogenous nerve growth factor (NGF). SCG were also co-cultured with neonatal rat heart (as positive control) or spinal cord (SC; as negative control). To determine whether inflammation affects the ability of lymphoid tissues to induce neurite outgrowth, we also examined MLN at various times after infecting rats with Nippostrongylus brasiliensis (Nb-MLN). In one series of experiments, a single lymphoid tissue explant was surrounded by four SCG at a distance of 1 mm. The extent of neurite outgrowth was determinded by counting the number of neurites 0.5 mm away from each ganglion at several time points. Adult thymus and, to a lesser extent, spleen had strong stimulatory effects on neurite outgrowth from SCG after 12 hr or more in culture. For thymus tissue, this was similar to the positive control heart explants. MLN from normal rats had minimal effect on neurite outgrowth; however, Nb-MLN showed a time-dependent enhancement of the neurite outgrowth, maximal at 3 weeks after infection. The relative efficacy of neurite outgrowth induction (heart ≥ thymus ≥ Nb-MLN ≥ spleen ≥ MLN ≥ SC) was confirmed in a second series of experiments where one SCG was surrounded by three different tissue explants. We then examined the role of 2.5S NGF, a well-known trophic factor for sympathetic nerves, in the lymphoid tissue-induced neurite outgrowth. Anti-NGF treatment of co-cultures of SCG and heart almost completely blocked the neurite outgrowth. Anti-NGF also significantly inhibited thymus- and spleen-induced neurite outgrowth, but not as effectively as heart-induced neuritogenesis (93,80, and 77% inhibition at 24 hr; 86,70, and 68% inhibition at 48 hr for heart, thymus, and spleen, respectively). On the other hand, anti-NGF inhibited only 8% of neurite outgrowth induced by 3-week post-infection Nb-MLN at 24 hr, and 41% at 48 hr. These data show that several adult rat lymphoid tissues exert neurotrophic/tropic effects. The predominant growth factor in thymus and spleen is NGF, while Nb-MLN produces factor(s) which is (are) immunologically distinguishable from NGF. These neurotrophic/tropic factors are produced during the reactive lymphoid hyperplasia that forms part of the inflammatory response against the nematode, N. brasiliensis. This suggests the possibility that cytokines produced by lymphocytes or other inflammatory cells may stimulate sympathetic neurite outgrowth in vivo. © 1994 Wiley-Liss, Inc. 相似文献
55.
本文用30例成人尸体观察了动脉韧带和左喉返神经,动脉韧带长1.2.97±4.53mm,圆索状动脉韧带23例(77%),直径为3.92±1.12mm。动脉韧带的主动脉端附着于主动脉弓(80%)或降主动脉(20%),肺动脉端附着于左肺动脉,6例肺动脉端位于心包内。19例(63%)左喉返神经绕主动脉弓,11例(37%)绕动脉韧带的主动脉端。 相似文献
56.
通过对10例小儿及23例成年人的喉内肌进行的myosin-ATPase等染色观察,得到小儿和成人各喉内肌不同的肌纤维构成比。成人PCAⅠ型纤维最多,LCA、INA及CT次之,TA最少。小儿的各喉内肌也有类似比例。表明不论小儿或成人,PCA均具有较强的抗疲劳性,适应呼吸作用的需要;TA具有较快的收缩速度,以适应发声及呼吸道保护作用。从纤维构成上看,小儿与成人相比,各喉内肌Ⅰ型纤维较为匮乏,表明小儿的喉在发声及呼吸道保护等功能方面尚不够完善。 相似文献
57.
The distribution of GABA-producing neurons in the brainstem auditory nuclei of the rat was investigated immunohistochemically by using an antibody to glutamic acid decarboxylase (GAD). In the cochlear nuclei, GAD immunoreactive neurons are present only in the superficial granular and molecular layers, whereas terminals are found in all subdivisions of the nuclei and are particularly dense surrounding large spherical cells and one type of stellate cell. In the superior olivary complex, GAD immunoreactive neurons are located in the lateral olivary nucleus and throughout the periolivary region. Immunoreactive terminals are distributed along dendrites of principal cells of the medial and lateral olivary nuclei and are clustered around somata of globular neurons of the nucleus of the trapezoid body. An extremely dense band of immunoreactive somata and terminals is present along the ventral edge of the olivary complex. The ventral, intermediate, and dorsal nuclei of the lateral lemniscus contain small fusiform GAD-immunoreactive neurons and a moderately dense plexus of immunoreactive terminals. The inferior colliculus contains a large population of GAD-immunoreactive perikarya and an extremely dense accumulation of immunoreactive terminals in the central, dorsomedial, and external nuclei. These observations indicate that GABA systems are involved in function at all levels of the brainstem auditory pathway. 相似文献
58.
健康和病变人声带振动特性声门图 总被引:1,自引:0,他引:1
本文用多功能声门图仪测定了健康受试者(男46名,女34名)和不同喉病患者(男134名,女87名)声门图的波形及其特征参数。根据测出的正常声门图及其参数分布研究了恶性喉病变、声带麻痹、喉内关节病变、功能性声门发声障碍、声带息肉、声带小结、喉炎和早期喉病的临床声门图表现及其与声带振动模式变异之间的关系,并探讨了上述病变声门图的鉴别诊断指标和用声门图对喉病手术治疗、药物治疗和功能治疗的疗效进行定性和定量评价。研究结果证实:声门图方法能准确、定量、灵敏地反映声带振动模式及其变异;在喉病诊治中具有重要的应用价值。 相似文献
59.
Neuronal adrenergic and muscular cholinergic contractile hypersensitivity in canine jejunum after extrinsic denervation 总被引:1,自引:1,他引:0
Bruno M. Balsiger M.D. Chong-Liang He M.D. Nicholas J. Zyromski M.D. Michael G. Sarr M.D. 《Journal of gastrointestinal surgery》2003,7(4):572-582
Extrinsic denervation may be responsible for motor dysfunction after small bowel transplantation. The aim of this study was
to examine the role of extrinsic innervation of canine jejunum on contractile activity. An in vitro dose response of cholinergic
and adrenergic agonists was evaluated in canine jejunal strips of circular muscle at 0, 2, and 8 weeks in a control group
and after jejunoileal extrinsic denervation (EX DEN). Neurons in circular muscle were quantitated by means of immunohistochemical
techniques. Adrenergic and cholinergic responses did not differ at any time in the control group. However, at 2 and 8 weeks,
extrinsic denervation caused an increased sensitivity to the procontractile effects of the cholinergic agonist bethanechol
at the level of the smooth muscle cells, and increased sensitivity to the inhibitory effects of the adrenergic agent norepinephrine
mediated at the level of the enteric nervous system. Immunohistochemical analysis showed a reduction in all neurons and a
complete lack of adrenergic fibers in the EX DEN group after 2 and 8 weeks. Extrinsic denervation induces enteric neuronal
cholinergic and adrenergic smooth muscle hypersensitivity in canine jejunal circular muscle.
Presented in part at the annual meeting of the American Gastroenterological Association, Orlando, Florida, May 18, 1999 (poster
presentation), and published as an abstract in Gastroenterology 116:A1075, 1999.
Supported by United States Public Health Service grant DK39337 from the National Institutes of Health (M.G.S.); the Swiss
National Science Foundation; the Swiss Society of Gastroenterology and Hepatology; the Swiss Foundation for Medical and Biological
Science; the Novartis Foundation; Astra Zeneca Pharmaceuticals, Switzerland; and the Department of Visceral and Transplantation
Surgery, University of Bern, Switzerland. 相似文献
60.
K Alderson 《Muscle & nerve》1992,15(11):1284-1289
The presence, morphology, distribution, and abundance of axonal swellings in intramuscular nerves were evaluated. Axonal swellings were present in intramuscular nerves in 42% of 127 muscle biopsies from patients with a variety of conditions. The incidence was highest in muscle from patients with peripheral neuropathy, but swellings were present in muscle from patients with motor neuron disease, primary muscle diseases, and some individuals without clinical or histological evidence of neuromuscular disease. The greatest number of swellings in intramuscular nerves was in muscle from patients with chronic inflammatory demyelinating neuropathy. Swellings were spherical or elliptical, 4-20 microns in diameter, 5-30 microns in length, and composed of neurofilaments. Swellings were present only in myelinated axons of intramuscular nerves, proximal to nodes of Ranvier or in internodal regions. Swellings were not associated with axonal degeneration. They were probably not transported. The formation or accumulation of swellings may reflect altered axonal dynamics common to a number of disease processes. 相似文献