全文获取类型
收费全文 | 2928708篇 |
免费 | 245792篇 |
国内免费 | 12952篇 |
专业分类
耳鼻咽喉 | 40149篇 |
儿科学 | 92828篇 |
妇产科学 | 73833篇 |
基础医学 | 481939篇 |
口腔科学 | 78253篇 |
临床医学 | 264476篇 |
内科学 | 499373篇 |
皮肤病学 | 82981篇 |
神经病学 | 252061篇 |
特种医学 | 113938篇 |
外国民族医学 | 88篇 |
外科学 | 458360篇 |
综合类 | 88759篇 |
现状与发展 | 23篇 |
一般理论 | 2154篇 |
预防医学 | 252205篇 |
眼科学 | 66569篇 |
药学 | 197526篇 |
24篇 | |
中国医学 | 8588篇 |
肿瘤学 | 133325篇 |
出版年
2022年 | 23029篇 |
2021年 | 54917篇 |
2020年 | 35085篇 |
2019年 | 58246篇 |
2018年 | 70436篇 |
2017年 | 53598篇 |
2016年 | 58887篇 |
2015年 | 73534篇 |
2014年 | 107692篇 |
2013年 | 173062篇 |
2012年 | 77873篇 |
2011年 | 76271篇 |
2010年 | 113260篇 |
2009年 | 118563篇 |
2008年 | 63432篇 |
2007年 | 64476篇 |
2006年 | 76046篇 |
2005年 | 71604篇 |
2004年 | 73832篇 |
2003年 | 64988篇 |
2002年 | 55051篇 |
2001年 | 74130篇 |
2000年 | 66170篇 |
1999年 | 71699篇 |
1998年 | 62120篇 |
1997年 | 60524篇 |
1996年 | 58328篇 |
1995年 | 53818篇 |
1994年 | 47947篇 |
1993年 | 44899篇 |
1992年 | 47969篇 |
1991年 | 46306篇 |
1990年 | 43926篇 |
1989年 | 43895篇 |
1988年 | 40776篇 |
1987年 | 39951篇 |
1986年 | 37984篇 |
1985年 | 38889篇 |
1984年 | 38560篇 |
1983年 | 36099篇 |
1982年 | 38132篇 |
1981年 | 36372篇 |
1980年 | 34377篇 |
1979年 | 30929篇 |
1978年 | 29764篇 |
1977年 | 27767篇 |
1976年 | 25497篇 |
1975年 | 24160篇 |
1974年 | 23875篇 |
1973年 | 22653篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
O. GAROFALO P. G. E. KENNEDY M. SWASH† J. E. MARTIN† P. LUTHERT B. H. ANDERTON P. N. LEIGH 《Neuropathology and applied neurobiology》1991,17(1):39-45
The expression of two heat shock proteins, HSP72 and p57, in addition to ubiquitin, has been studied immunocytochemically in nine amyotrophic lateral sclerosis (ALS) cases and 10 age-matched controls. HSP72 and p57 antibodies did not identify the characteristic ubiquitin-immunoreactive inclusions present in anterior horn cells in ALS spinal cord. Antibodies to HSP72, but not to p57 or ubiquitin, strongly labelled structures corresponding to polyglucosan bodies in spinal grey matter. Such immunoreactive profiles were more abundant in ALS cases, although they were also present in control material. They were sometimes identified by haematoxylin and eosin and periodic acid Schiff reaction, but were not labeled by phosphotungstic acid haematoxylin or by antibodies to glial fibrillary acidic protein. Although ubiquitin, HSP72 and p57 are stress-induced proteins, they are expressed differently and might therefore have different significance in neuronal degeneration. 相似文献
992.
Laser-light scattering was used to observe and quantify the dynamics of human blood platelet aggregation in platelet-rich plasma (PRP). Aggregation was performed in a controlled shear environment by placing the PRP in the annular space between a rotating cylindrical rod and a stationary cylindrical tube. The instrument was capable of very sensitive continuous semi-quantitative measurements of chemically-induced microaggregation. As a demonstration of the technique, results are presented for ADP-induced aggregation at doses of 10, 1, and 0.1 microM and collagen-induced aggregation at a dose of 5 micrograms/ml, each at shear rates of 1,000 s-1 and 500 s-1. Extensive aggregation was observed in response to ADP at even the low dose of 0.1 microM, indicating a high sensitivity to microaggregates. The sensitivity of the ultimate size of the ADP-induced aggregates to ADP concentration was shear dependent. The formation of microaggregates by collagen stimulation was shown to be almost immediate, as contrasted with a 10-20 s typical lag when observed turbidometrically. Disaggregation was observed with 1 microM ADP, but this was only partial, as contrasted with the complete recovery of transmittance observed in the turbidometric technique. Electronic particle sizing and counting was employed to semiquantitatively verify the aggregate size distributions found from mathematical conversion of the laser-light scattering data. 相似文献
993.
994.
Acupuncture analgesia (AA) caused by low frequency stimulation of the acupuncture point (AP) was abolished by hypophysectomy and adrenalectomy. Termination of the AA producing pathway from the AP to the pituitary gland was in the medial hypothalamic arcuate nucleus (M-HARN). The origin of the descending pain inhibitory system associated with AA was in the posterior HARN (P-HARN). AA in the hypophysectomized rats, and enhanced neuronal activity in the P-HARN that were abolished during acupuncture stimulation, were both restored by intraperitoneal microinjection of 0.5 mg/kg morphine or 0.1 micrograms beta-endorphin into the P-HARN during acupuncture stimulation. Of the analgesia produced by dopamine or beta-endorphin injected into the P-HARN, that caused by beta-endorphin disappeared after denervation of the M-HARN. The P-HARN neurons that responded to acupuncture stimulation also responded to iontophoretic dopamine, but not to iontophoretic morphine nor ultramicroinjected beta-endorphin. The transmission between the M-HARN and P-HARN may be dopaminergic, and beta-endorphin might presynaptically modulate this transmission. Reduction of sodium ions may have been the reason for abolition of AA after adrenalectomy. 相似文献
995.
Bronchoalveolar lavage fluid neutrophils were studied by the cytologic methods in 58 patients with chronic bronchitis, 63 ones with bronchiectasis, and 8 normal controls. The study included cytospectrophotometry of myeloperoxidase and alkaline phosphatase activity and estimation of active oxygen-producing cells in the NBT test. Neutrophilic functional activity was different in the patients with chronic bronchitis and bronchiectasis. Neutrophilic myeloperoxidase and alkaline phosphatase activities were lower in the patients with chronic bronchitis than in those with bronchiectasis, whereas the counts of cells active in the NBT test were low in both patient populations. 相似文献
996.
997.
This study was undertaken to assess the role of the hypothalamus and medulla oblongata in regulation of liver circulation in anesthetized dogs. Blood pressure, flow in hepatic artery and portal vein, and shifts of blood volume in the liver were recorded. Stimulation of the anterior hypothalamus produced changes in arterial pressure which were followed by passive changes in hepatic arterial blood flow; changes in hepatic artery resistance were rather small. Stimulation of the medial and posterior hypothalamus increased hepatic arterial resistance by 65-170%. Liver portal blood flow during stimulation of most of the hypothalamic sites decreased, hepatic portal pressure rose and vascular portal venous resistance increased 2.5-3 times. Three areas only (sympatho-inhibitory area, paraventricular and lateral hypothalamic nuclei) when stimulated produced dilatation of hepatic portal and splanchnic vascular beds, thus increasing portal blood flow. All cases of stimulation led to the decrease of blood volume in the liver by 10-36%. Stimulation of medullary structures (n. tractus solitarii, reticular nn.) caused similar changes in hepatic circulation, however the amplitude of reaction was 1.5-6 times smaller than upon hypothalamic stimulation. Central impulses to the hepatic vessels are transmitted by sympathetic adrenergic nerve fibers through vascular alpha-adrenoreceptors. It is concluded that the hypothalamic level of the central nervous system, unlike the bulbar one, exerts considerable, differentiated, well coordinated and to some extent specific influences on hepatic circulation. 相似文献
998.
Unfractionated cytokines have been shown to induce in vitro proliferation of neonatal rat Schwann cells but the nature of the mitogen(s) is not known. A mixture of rabbit antibodies specific for recombinant interleukin-1α (IL-1α) and interleukin-1β (IL-1β) inhibited Schwann cell proliferation induced by unfractionated human cytokines whereas antibodies to interleukin-2 (IL-2) and control IgG did not. However, purified human IL-1 and recombinant human IL-1α or β did not induce Schwann cell proliferation on their own. 相似文献
999.
Summary Two contrasting cases of cervical intramedullary cavernous angioma in young female patients are reported. One patient had a 3-year course of step-wise progressive tetraparesis; at each of the five events intramedullary bleeding from a cryptic vascular malformation at C6–7 level was diagnosed by MRI. The other patient presented with one episode which led to MRI diagnosis of a vascular malformation at the C2 level. Both patients eventually underwent complete surgical excision of the angioma with subsequent steady improvement of the neurological deficit. 相似文献
1000.