全文获取类型
收费全文 | 704919篇 |
免费 | 312397篇 |
国内免费 | 64206篇 |
专业分类
耳鼻咽喉 | 6775篇 |
儿科学 | 9047篇 |
妇产科学 | 9274篇 |
基础医学 | 145173篇 |
口腔科学 | 10474篇 |
临床医学 | 123982篇 |
内科学 | 161379篇 |
皮肤病学 | 9272篇 |
神经病学 | 45777篇 |
特种医学 | 25181篇 |
外国民族医学 | 305篇 |
外科学 | 88240篇 |
综合类 | 124535篇 |
现状与发展 | 107篇 |
一般理论 | 40篇 |
预防医学 | 67615篇 |
眼科学 | 28889篇 |
药学 | 102359篇 |
465篇 | |
中国医学 | 69088篇 |
肿瘤学 | 53545篇 |
出版年
2023年 | 8068篇 |
2022年 | 18416篇 |
2021年 | 25779篇 |
2020年 | 22269篇 |
2019年 | 27413篇 |
2018年 | 28926篇 |
2017年 | 27813篇 |
2016年 | 25418篇 |
2015年 | 32280篇 |
2014年 | 36708篇 |
2013年 | 34149篇 |
2012年 | 45206篇 |
2011年 | 50895篇 |
2010年 | 38512篇 |
2009年 | 41196篇 |
2008年 | 35967篇 |
2007年 | 33273篇 |
2006年 | 33135篇 |
2005年 | 33093篇 |
2004年 | 25457篇 |
2003年 | 23530篇 |
2002年 | 21668篇 |
2001年 | 22410篇 |
2000年 | 19074篇 |
1999年 | 25071篇 |
1998年 | 21361篇 |
1997年 | 21227篇 |
1996年 | 20574篇 |
1995年 | 20333篇 |
1994年 | 19147篇 |
1993年 | 16246篇 |
1992年 | 16819篇 |
1991年 | 15521篇 |
1990年 | 13978篇 |
1989年 | 13384篇 |
1988年 | 12571篇 |
1987年 | 11649篇 |
1986年 | 10914篇 |
1985年 | 9724篇 |
1984年 | 7290篇 |
1983年 | 7082篇 |
1982年 | 7914篇 |
1981年 | 7395篇 |
1980年 | 7011篇 |
1979年 | 6928篇 |
1978年 | 5927篇 |
1977年 | 6242篇 |
1976年 | 5825篇 |
1975年 | 5578篇 |
1974年 | 5177篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Transplantation of microencapsulated bovine chromaffin cells reduces lesion-induced rotational asymmetry in rats 总被引:7,自引:0,他引:7
Surrounding bovine chromaffin cells by a semipermeable membrane may protect the transplanted cells from a host immune response and shield them from the inflammatory process resulting from the surgical trauma. Encapsulation of the chromaffin cells was achieved by inter-facial adsorption of a polycation on a polyanionic colloid matrix in which the chromaffin cells were entrapped. Basal and potassium-evoked release of catecholamines from encapsulated bovine chromaffin cells was analyzed over a 4-week period in vitro. Norepinephrine and dopamine release remained constant over time whereas epinephrine release significantly decreased. The chromaffin cells also retained the capacity for depolarization-elicited catecholamine release 4 weeks following the encapsulation procedure. Morphological analysis revealed the presence of intact chromaffin cells with well-preserved secretory granules. Striatial implantation of chromaffin cell-loaded capsules significantly reduced apomorphine-induced rotation compared to empty polymer capsules in animals lesioned with 6-hydroxydopamne frr at least 4 weeks. Intact chromaffin cells expressing tyrosine hydroxylase and dopamine-β-hydroxylase were observed in all capsules implanted in the striatum for 4 weeks. The assessment of the clinical potential of transplanting encapsulated adrenal chromaffin cells of either allo- or xenogeneic origin for Parkinson's disease will require long-term behavioral studies. The present study suggests, however, that the polymer encapsulation procedure may offer an alternative to adrenal autografts as a source of dopaminergic tissue. 相似文献
992.
Dissection of the extracranial vertebral artery: report of four cases and review of the literature.
下载免费PDF全文
![点击此处可从《Journal of neurology, neurosurgery, and psychiatry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
P Hinse A Thie L Lachenmayer 《Journal of neurology, neurosurgery, and psychiatry》1991,54(10):863-869
Four cases of cervical vertebral artery (VA) dissection are reported. In three patients VA dissection was associated with neck trauma. All patients were young or middle-aged (range 27 to 49 years). In two there was a history of migraine. Pain preceded neurological symptoms from hours to six weeks. Three patients had neurological deficits including elements of the lateral medullary syndrome, and one experienced recurrent transient ischaemic attacks in the vertebrobasilar territory. Angiographic findings included irregular stenosis, occlusion and pseudoaneurysm; in two patients VA abnormalities were bilateral. All patients were treated with anticoagulants and improved. In a review of 28 cases with traumatic dissection and 29 cases with spontaneous dissection of the VA reported in the literature, distinct clinical and angiographic features emerge. Aetiology remains obscure in most cases of spontaneous dissection and management is still controversial. 相似文献
993.
BACKGROUND. Studies have documented the potential contributions of preventive health care programs. Yet little is known about which screening tests should be included in public health programs for older persons. This study offers recommendations regarding these tests. METHODS. The recommendations come from synthesizing the findings of the US Preventive Services Task Force, the literature, and the consensus of experts in geriatrics, gerontology, and health policy research. The literature was evaluated to identify methodologically sound studies of the prevalence of selected disorders and benefits and availability of screening procedures for those disorders. Experts from various fields specializing in the care of the elderly formed panels to assist in evaluating the literature and providing further information from gerontological and public health perspectives. RESULTS. We recommend vision testing for refractive error; inspection of the skin surface for fungal infection and skin cancer, drug eruptions, and xerosis; a history for symptoms of xerosis; audiometric testing for presbycusis; surveys for hearing loss; otoscopic inspection for cerumen impaction; dental examination for caries; measurement of blood pressure for hypertension; and breast examination and mammography for cancer. CONCLUSIONS. Our study suggests that these screening procedures are useful for public health screening programs. More information is needed on the effects of screening services on the health and functioning of older persons. 相似文献
994.
用5只猫于左侧颈部食管壁内注入 HRP 溶液,通过 HRP 逆行追踪法研究颈部食管的交感神经支配,结果表明:1.长轴突型交感节前神经元直接分布到食管壁内,其标记细胞位于双侧脊髓的胸1~3节段,以胸2节段最多(占标记细胞总数的66.45%),注射侧占优势。标记细胞主要位于中间带外侧核(约占95.02%),其次为侧索、中介核、前角腹后外侧核。其细胞形态不一,以中小型细胞为主(占标记细胞总数的90.4%)。2.支配颈部食管的交感节后神经元主要位于星状神经节(约占61.99%),余者位于双侧颈前、中和2~5胸交感节内、以小细胞最多。 相似文献
995.
996.
L Wang 《中华耳鼻咽喉科杂志》1989,24(4):209-11, 254
For a systematic understanding of the effect of diving on hearing ability and middle and inner ear morphology, we have carried out simulated tests on 65 healthy guinea pigs, under water 60 meters deep, and then decompress rapidly. The tests proved that hearing ability changed most significantly 7 days after diving. After diving, all tympanogram curves, except those in 3 ears, changed to type B. Thirty-nine (37.85%) middle ears had been damaged, 4 (3.88%) had inner ears injured, as seen under light microscope. During decompression, three animals had nystagmus. Screen electronmicroscopy showed hair cell destruction and hair derangement. Transmission electronmicroscopy showed mitochondria damage. The results showed that damages in middle and inner ears were mainly mechanical, sometimes metabolic. 相似文献
997.
青蒿琥酯皮肤擦剂在小鼠和兔体内的药代动力学研究 总被引:1,自引:0,他引:1
将青蒿琥酯溶于苯二甲酸二甲酯,加适量氨酮制成皮肤擦剂。给兔脱毛后,皮肤涂抹此擦剂25mg/kg后,血药浓度达峰时间平均为2 h,峰浓度平均为1.80μg/ml。药物在兔体内平均驻留时间为3.54 h,清除半衰期约为2.46 h。给小鼠脱毛皮肤涂抹擦剂6.7,31.3和71.4 mg/kg,血药浓度在给药后0.5~4 h达高峰,峰浓度分别为0.82,2.05和7.11μg/ml,体内药物平均驻留时间为3.39,2.79及3.54 h,清除半衰期为2.35,1.93及2.45 h。可见,给兔及小鼠皮肤擦剂后,青蒿琥酯吸收良好,血药浓度维持时间较长。 相似文献
998.
Toward a model for improved targeting of aged at risk of institutionalization. 总被引:3,自引:1,他引:2
下载免费PDF全文
![点击此处可从《Health services research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A national sample of institutionalized and noninstitutionalized aged was created by merging the 1977 National Nursing Home Survey and its counterpart, the National Health Interview Survey for the same year. A weighted logistic regression analysis was conducted to identify factors that might be useful in calculating home- and community-based long-term care clients' risk of institutionalization. A model containing patient characteristics, nursing home bed supply, and a climate variable correctly classified 98.2 percent of cases residing in nursing homes or the community. Physical dependency, mental disorder and degenerative disease, lack of spouse, being white, poverty, old age, unoccupied nursing home beds, and climate all appear to be determinants of institutional residency among the aged. 相似文献
999.
作者用同位数前体参入法及透射与扫描电镜研究了平阳霉素(博莱霉素A_5)对HeLa细胞大分子生物合成及超微结构的影响。结果显示:平阳霉素能抑制HeLa细胞DNA,RNA和蛋白质的生物合成,对DNA的抑制作用强,ID_(50DNA)为42.77μg/ml。表现为:染色质减少,核内电子密度低,核仁分离及“核仁帽”形成,细胞表面微绒毛消失或变形,最终导致质膜破裂等。作者认为,细胞膜是否为此类药物作用的靶位值得进一步研究。 相似文献
1000.
应用电子计算机计算血液流变学的正常值及分析 总被引:4,自引:0,他引:4
为评价血流粘滞诸因素生理与病理的异常,对济南地区338例正常人血液流变学的各项指标进行了检测,统计了血液流变学各项指标的总平均及男女的平均值和正常范围,并计算了血液流变学各项指标间的相关系数。 相似文献