全文获取类型
收费全文 | 204604篇 |
免费 | 12096篇 |
国内免费 | 569篇 |
专业分类
耳鼻咽喉 | 2481篇 |
儿科学 | 6357篇 |
妇产科学 | 4357篇 |
基础医学 | 28047篇 |
口腔科学 | 8570篇 |
临床医学 | 15988篇 |
内科学 | 45884篇 |
皮肤病学 | 4876篇 |
神经病学 | 17250篇 |
特种医学 | 6288篇 |
外国民族医学 | 26篇 |
外科学 | 25156篇 |
综合类 | 1621篇 |
现状与发展 | 2篇 |
一般理论 | 82篇 |
预防医学 | 20939篇 |
眼科学 | 3736篇 |
药学 | 12701篇 |
中国医学 | 797篇 |
肿瘤学 | 12111篇 |
出版年
2023年 | 1212篇 |
2022年 | 2492篇 |
2021年 | 4711篇 |
2020年 | 3132篇 |
2019年 | 4563篇 |
2018年 | 6115篇 |
2017年 | 4541篇 |
2016年 | 4315篇 |
2015年 | 5031篇 |
2014年 | 6837篇 |
2013年 | 8680篇 |
2012年 | 13524篇 |
2011年 | 14049篇 |
2010年 | 7132篇 |
2009年 | 6442篇 |
2008年 | 10770篇 |
2007年 | 11462篇 |
2006年 | 10413篇 |
2005年 | 10794篇 |
2004年 | 10072篇 |
2003年 | 9104篇 |
2002年 | 7111篇 |
2001年 | 5394篇 |
2000年 | 5252篇 |
1999年 | 4694篇 |
1998年 | 1809篇 |
1997年 | 1486篇 |
1996年 | 1415篇 |
1995年 | 1228篇 |
1994年 | 1185篇 |
1993年 | 1089篇 |
1992年 | 2804篇 |
1991年 | 2684篇 |
1990年 | 2461篇 |
1989年 | 2443篇 |
1988年 | 2191篇 |
1987年 | 2034篇 |
1986年 | 1915篇 |
1985年 | 1824篇 |
1984年 | 1306篇 |
1983年 | 1059篇 |
1982年 | 613篇 |
1981年 | 557篇 |
1980年 | 512篇 |
1979年 | 957篇 |
1978年 | 638篇 |
1977年 | 502篇 |
1975年 | 574篇 |
1974年 | 572篇 |
1973年 | 566篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
21.
22.
23.
24.
Alcoholic liver disease: an IgA-associated disorder 总被引:1,自引:0,他引:1
25.
26.
27.
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
28.
S J Graafsma L J van Tits P van Heijst J Reyenga J F Rodrigues de Miranda T Thien 《Journal of cardiovascular pharmacology》1989,14(4):598-602
The effect of handgrip (HG) isometric exercise on plasma catecholamines, alpha 2-adrenoceptors on platelets and beta 2-adrenoceptors on lymphocytes was studied in normotensive subjects (NT) and essential hypertensive subjects (HT). Whereas systolic blood pressure (SBP) increases were similar in NT and HT subjects, diastolic blood pressure (DBP) and heart rate (HR) increased more in the former group. Baseline values and changes in plasma epinephrine (E) and norepinephrine (NE) did not differ between both groups. No differences were apparent in alpha 2-adrenoceptor density and affinity between NT and HT subjects before or after the test. HG isometric exercise induced a similar increase in beta 2-adrenoceptors on lymphocytes of 22 +/- 7 and 13 +/- 5% in NT and HT subjects, respectively. Affinity to the beta 2-adrenoceptors under baseline conditions was somewhat lower in HT (8.1 +/- 0.4 pM) than in NT subjects (6.5 +/- 0.5 pM), and this difference persisted during the test. Our results indicate that there are no differences in alpha 2- and beta 2-adrenoceptor densities either at baseline conditions or after HG isometric exercise between NT and HT subjects. Small differences noted in affinity to the beta 2-adrenoceptors require further investigation. 相似文献
29.
M. D. Taylor M. L. de Ceballos S. Rose P. N. Chong P. Jenner C. D. Marsden 《Journal of neural transmission (Vienna, Austria : 1996)》1991,3(2):99-108
Summary Aged common marmosets were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 0.5–2.0 mg/kg/week i.p.) for 16 or 24 weeks, observed for a total of 30 weeks and then killed for measurement of biochemical pramaters in basal ganglia. The MPTP treatment induced a marked depletion in dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid levels in the caudate nucleus and putamen. In contrast, the concentrations of five neuropeptides: [Met5]-enkephalin, [Leu5]-enkephalin, cholecystokinin, substance P and neurotensin as measured by a combined HPLC/RIA method, remained unaltered in all basal ganglia regions examined. Enkephalin precursor levels, as reflected by cryptic [Met5]-enkephalin content, were increased in the putamen, but not in the caudate nucleus, as a consequence of MPTP administration. Cryptic [Leu5]-enkephalin content remained unchanged in the striatum of MPTP treated marmosets. Overall, these results suggest an increase in striatal [Met5]-enkephalin release following chronic MPTP treatment of aged marmosets. However, the chronic treatment of aged marmosets with MPTP does not reproduce the neuropeptide alterations characteristic of Parkinson's disease. 相似文献
30.
D. Caroline Blanchard Jon K. Shepherd Antonio De Padua Carobrez Robert J. Blanchard 《Neuroscience and biobehavioral reviews》1991,15(4):461-468
Female rats consistently show a pattern of differences in defensive behaviors compared to males which parallel the effects of exposure to a nonpainful threat stimulus (cat or cat odor) in the same tests and measures. These indications of greater defensiveness for females are particularly common in situations involving potential, as opposed to actual and present, threat, a factor which probably also reflects ceiling or floor effects in situations involving very intense defensiveness. In addition, pharmacological studies indicate sex differences in the effects of selective serotonin (5-HT) receptor agonists and antagonists on defensive responding. These findings indicate that sex effects must be considered in studies of the pharmacological control of defensive behaviors, and suggest that responsivity to sex effects may be an additional criterion for the suitability of animal models of anxiety. 相似文献