全文获取类型
收费全文 | 1683408篇 |
免费 | 115962篇 |
国内免费 | 2414篇 |
专业分类
耳鼻咽喉 | 23524篇 |
儿科学 | 55757篇 |
妇产科学 | 47816篇 |
基础医学 | 256653篇 |
口腔科学 | 45463篇 |
临床医学 | 145961篇 |
内科学 | 323417篇 |
皮肤病学 | 36088篇 |
神经病学 | 126034篇 |
特种医学 | 65422篇 |
外国民族医学 | 410篇 |
外科学 | 257600篇 |
综合类 | 32884篇 |
现状与发展 | 2篇 |
一般理论 | 399篇 |
预防医学 | 123526篇 |
眼科学 | 38945篇 |
药学 | 128776篇 |
2篇 | |
中国医学 | 3358篇 |
肿瘤学 | 89747篇 |
出版年
2018年 | 16253篇 |
2016年 | 13862篇 |
2015年 | 15821篇 |
2014年 | 21643篇 |
2013年 | 32720篇 |
2012年 | 45905篇 |
2011年 | 49654篇 |
2010年 | 29122篇 |
2009年 | 27023篇 |
2008年 | 47285篇 |
2007年 | 51491篇 |
2006年 | 51775篇 |
2005年 | 50437篇 |
2004年 | 48767篇 |
2003年 | 47389篇 |
2002年 | 46401篇 |
2001年 | 74482篇 |
2000年 | 76440篇 |
1999年 | 64591篇 |
1998年 | 18253篇 |
1997年 | 16082篇 |
1996年 | 16365篇 |
1995年 | 15414篇 |
1994年 | 14488篇 |
1993年 | 13553篇 |
1992年 | 51590篇 |
1991年 | 51976篇 |
1990年 | 51552篇 |
1989年 | 50224篇 |
1988年 | 46747篇 |
1987年 | 45940篇 |
1986年 | 43580篇 |
1985年 | 41656篇 |
1984年 | 31049篇 |
1983年 | 26875篇 |
1982年 | 15562篇 |
1981年 | 13867篇 |
1979年 | 29583篇 |
1978年 | 20833篇 |
1977年 | 17778篇 |
1976年 | 17237篇 |
1975年 | 19353篇 |
1974年 | 22590篇 |
1973年 | 21774篇 |
1972年 | 20555篇 |
1971年 | 19298篇 |
1970年 | 18020篇 |
1969年 | 17148篇 |
1968年 | 16165篇 |
1967年 | 14334篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
961.
Gamma-aminobutyric acid (GABA) in the thalamus has mainly been associated with the inhibitory modulation of the sensory and cortical flow of information via a 'classical', chloride-dependent, GABAA receptor-mediated action. However, the discovery of a late, long-lasting potassium-dependent inhibitory postsynaptic potential (IPSP) mediated by GABAB receptors present on thalamocortical cells, has allowed new insights into our understanding of the physiological role of this neurotransmitter. In particular, work on the dorsal lateral geniculate nucleus indicates that together with a relatively weak inhibition, GABAB receptor-mediated IPSPs 'prepare' thalamocortical cells for burst firing by activating low-threshold calcium potentials. Thus, GABA in the thalamus can no longer be viewed only as a 'classical' inhibitory transmitter but also as a neuromodulator with a 'priming' role for burst firing excitation. This dual role of GABAB receptors in inhibition and excitation of thalamocortical cells might allow different interpretations of earlier findings in animals and humans, both in healthy and pathological conditions. It will also help to identify new functions for postsynaptic GABAB receptors in other parts of the central nervous system. 相似文献
962.
The ontogeny of type I and type II benzodiazepine binding sites was studied in mouse cerebellum by displacement of [3H]flunitrazepam binding by zolpidem, a ligand specific for the type I sites. Type I binding sites predominate throughout development and in the adult while type II sites account for 25% of total cerebellar benzodiazepine binding sites at birth and, during development, decrease to 10% or less in the adult. On a per cerebellum basis type II sites increase during the first postnatal week and then remain at a steady level while type I sites increase until adulthood. These results may indicate a specific localization of the type II sites (and of the corresponding alpha-protein subunits in the GABA/benzodiazepine receptor complex) in structures already present at birth and developing during a short early postnatal period. The affinity of zolpidem for its high affinity (type I) binding sites increases during cerebellar ontogeny, this increase possibly indicates an epigenetic (post-translational) 'maturation' process of the corresponding receptor molecule. Hill numbers indicate the existence of an additional binding site heterogeneity greater during development but still present in the adult; probably this is to be related to the simultaneous presence of different 'maturation' stages during development and with a certain variety of the final products. 相似文献
963.
964.
965.
G M Novotny 《The Journal of otolaryngology》1989,18(7):354-356
In 17 cases the author has removed intraglandular submandibular calculi by an oral route utilizing blunt soft tissue dissection after an incision of the mucosa only. General anesthesia is used and the patient discharged after an overnight stay. No complications were encountered. All patients were back on full diet in 48 hours. 相似文献
966.
R G Amedee W J Mann J M Gilsbach 《Archives of otolaryngology--head & neck surgery》1989,115(9):1103-1106
The anatomic principles and operative techniques currently applied to functional endoscopic endonasal surgery have allowed for significant refinements in another approach to regional pathology that uses the operating microscope, newly designed sinus instruments, and a self-retaining nasal speculum system. The main benefits of this method are the superb widefield stereoscopic vision and the distinct freedom to work bimanually. Additionally, direct bipolar cautery of bleeders is afforded while use of the observer tube or video allows for excellent teaching. The precise nature of this surgery affords less fear of serious complications in the treatment of periorbital, paranasal sinus, and parasellar diseases. We describe technical aspects of the surgery and associated complications in 219 patients treated from 1984 to 1987. 相似文献
967.
968.
969.
970.
C A González G López-Abente M Errezola A Escolar E Riboli I Izarzugaza M Nebot 《International journal of epidemiology》1989,18(3):569-577
A case-control study on bladder cancer was carried out in four regions of Spain. The study included 497 cases (438 males and 59 females), 583 hospital controls and 530 population controls matched by sex, age and residence. The present paper reports the results of the analyses on occupational history. Among men, an increased risk of bladder cancer was found for textile workers (OR = 1.97, 95% CL 1.2-3.3), mechanics and maintenance workers (OR = 1.86, 95% CL 1.2-2.8), workers in the printing industry (OR = 2.06, 95% CL 1.0-4.3) and for managers (OR = 2.03, 95% CL 1.2-3.5). The risk was highest among those first employed in the textile industry before the age of 25 and prior to 1960. Among mechanics the risk was highest for those who started after the age of 25 and later than 1960. The OR for smokers who had also been employed in one of the high risk occupations was 7.82 (95% CL 4.4-14.0) which is compatible with a multiplicative effect of joint exposure to tobacco and occupational hazards. 相似文献