全文获取类型
收费全文 | 4178篇 |
免费 | 341篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 28篇 |
儿科学 | 146篇 |
妇产科学 | 69篇 |
基础医学 | 561篇 |
口腔科学 | 86篇 |
临床医学 | 438篇 |
内科学 | 690篇 |
皮肤病学 | 41篇 |
神经病学 | 628篇 |
特种医学 | 482篇 |
外科学 | 530篇 |
综合类 | 100篇 |
预防医学 | 293篇 |
眼科学 | 39篇 |
药学 | 202篇 |
1篇 | |
中国医学 | 4篇 |
肿瘤学 | 191篇 |
出版年
2021年 | 41篇 |
2020年 | 45篇 |
2019年 | 54篇 |
2018年 | 53篇 |
2017年 | 50篇 |
2016年 | 53篇 |
2015年 | 87篇 |
2014年 | 97篇 |
2013年 | 142篇 |
2012年 | 127篇 |
2011年 | 162篇 |
2010年 | 111篇 |
2009年 | 133篇 |
2008年 | 138篇 |
2007年 | 166篇 |
2006年 | 168篇 |
2005年 | 127篇 |
2004年 | 133篇 |
2003年 | 111篇 |
2002年 | 110篇 |
2001年 | 112篇 |
2000年 | 102篇 |
1999年 | 117篇 |
1998年 | 104篇 |
1997年 | 110篇 |
1996年 | 122篇 |
1995年 | 90篇 |
1994年 | 72篇 |
1993年 | 84篇 |
1992年 | 81篇 |
1991年 | 71篇 |
1990年 | 104篇 |
1989年 | 126篇 |
1988年 | 88篇 |
1987年 | 100篇 |
1986年 | 109篇 |
1985年 | 118篇 |
1984年 | 65篇 |
1983年 | 50篇 |
1982年 | 46篇 |
1981年 | 44篇 |
1980年 | 54篇 |
1979年 | 39篇 |
1978年 | 35篇 |
1977年 | 32篇 |
1976年 | 36篇 |
1975年 | 40篇 |
1974年 | 23篇 |
1973年 | 26篇 |
1972年 | 27篇 |
排序方式: 共有4529条查询结果,搜索用时 0 毫秒
31.
Paul A.T. Kelly Isobel M. Ritchie Meharpal Sangra Miranda J.A. Cursham Emma M. Dickson Brenda Kelly Fiona P. Neilson M. Jason Reidy Martha C. Stevens 《Brain research》1994,665(2)
Cerebral blood flow and glucose utilization were measured in rat neocortex, hippocampus and striatum following methylenedioxymethamphetamine injection (5 mg/kg, i.v.), using the tracers [14C]iodoantipyrine and [14C]2-deoxyglucose, respectively. In control rats, blood flow was coupled to glucose metabolism, but in methylenedioxymethamphetamine-treated rats, marked hyperperfusion was measured in frontal and parietal cortex with no change in glucose use. This suggests that methylenedioxymethamphetamine has the potential to disrupt cerebrovascular control. 相似文献
32.
The phospholipid composition of a myeloid body (MB) enriched subcellular fraction of chick retinal pigment epithelium (RPE) was determined in order to further characterize the origin and functional significance of these lamellar membrane organelles. The major MB phospholipids found were phosphatidylcholine and phosphatidylethanolamine which represented 43% and 34% of the total MB lipids respectively. Sphingomyelin and phosphatidylinositol comprised the remaining detectable phospholipids. The fatty acyl chain composition of all detected phospholipids showed that the long-chain polyunsaturated fatty acids [arachidonic (20:4 n-6), docosapentaenoic (22:5 n-3) and docosahexaenoic (22:6 n-3)] account for greater than 45% of the fatty acids in MB membranes. This high proportion of long-chain polyunsaturated fatty acids in MBs is particularly striking when compared to the long-chain fatty acid composition of the photoreceptor outer segments from this predominantly cone retina which contains less than 25% long-chain polyunsaturated fatty acids. The results from this study clearly demonstrate that MB lipids represent a significantly enriched pool of long-chain polyunsaturated fatty acids. 相似文献
33.
To further understand the processes that lead to the formation of neurofibrillary tangles from paired helical filaments (PHF) in Alzheimer brains, we studied two morphologically distinct fractions of PHF separated on sucrose density gradient. In a fraction with mostly short and non-aggregated PHF, the majority of filaments could be solubilized in SDS. In a fraction containing primarily PHF aggregated into clusters or bundles, sometimes resembling neurofibrillary tangles, filaments were less soluble in SDS. Immunogold labelling with a panel of tau-immunoreactive antibodies demonstrated that N-terminal epitopes of tau were preserved in the short filaments, but were reduced or absent in aggregated filaments. In contrast, C-terminal epitopes were present in both fractions. Furthermore, the accessibility of the microtubule-binding domain to immunolabelling was markedly impaired in short and non-aggregated filaments compared to aggregated filaments. These results are consistent with proteolytic degradation of the N-terminal epitopes and preservation of the C-terminal epitopes and the microtubule-binding domain of tau in the aggregated filaments. Partial proteolysis may be involved in the generation of aggregated PHF in neurofibrillary tangles. 相似文献
34.
35.
Anderson RA; Evans LW; Irvine DS; McIntyre MA; Groome NP; Riley SC 《Human reproduction (Oxford, England)》1998,13(12):3319-3325
Follistatin is a binding protein for the activin and inhibin family of
hormones, regulating their biological activity. In the male reproductive
tract, the interaction of these factors is likely to be involved in the
regulation of the proliferation of several cell types. We have investigated
the presence of follistatin and activin A in seminal plasma using specific
immunoassays and have localized follistatin and activin/inhibin subunits in
the adult human testis, prostate and seminal vesicle to establish their
likely sources. High concentrations of immunoreactive follistatin were
present in seminal plasma in normal men (mean 97.9 ng/ml; 1.43 ng/ml in
peripheral plasma) and were similar in men with oligo/azoospermia and
following vasectomy. Follistatin immunoreactivity was localized to both
Leydig and Sertoli cells of the testis, and to epithelial cells of the
prostate gland and seminal vesicle, which are likely to be the predominant
sources of the hormone in seminal plasma. Activin A was also present in
seminal plasma in normal men but was undetectable following vasectomy, thus
deriving from the testis. Consistent with this finding, the betaA-subunit
was immunolocalized in Sertoli and Leydig cells but was not present in
seminal vesicle or prostate gland. The functional significance of the high
concentrations of follistatin secreted into seminal plasma by the prostate
gland and/or seminal vesicle is uncertain, but they may regulate the
biological activity of testis-derived activin A and inhibin B.
相似文献
36.
R Dixon AM Hughes K Nairn M Sellers JV Kemp RA Yates 《Cephalalgia : an international journal of headache》1998,18(7):468-475
Zolmitriptan (ZomigTM ) is a 5HT1B/1D agonist which has the ability to cross the intact blood-brain barrier to access central as well as peripheral receptors. Because of the potential for central nervous system side effects, this randomized, double-blind, placebo-controlled, 6-period crossover study evaluated the effects of 2.5 and 5 mg doses of zolmitriptan on psychomotor performance and investigated any pharmacodynamic or pharmacokinetic interaction with diazepam. Twelve healthy volunteers received the following "treatments" as single doses: zolmitriptan 2.5 mg, zolmitriptan 5 mg, diazepam 10 mg, zolmitriptan 2.5 mg+diazepam 10 mg, zolmitriptan 5 mg+diazepam 10 mg and placebo. Pre-dose and at 1, 4, 8, and 24 h post-dose, the following validated battery of psychomotor tests was performed: Bond-Lader visual analogue scales (calmness, contentedness, and alertness factors), critical flicker fusion test, choice reaction time (recognition, motor, and total reaction times), finger-tapping test, number cancellation test and digit symbol substitution test. Plasma concentrations of zolmitriptan, its active metabolite, and diazepam and its active metabolites were measured at the same timepoints. Zolmitriptan 2.5 and 5 mg had no effect on psychomotor function when given alone. In contrast, diazepam 10 mg had profound effects, consistent with its sedative properties, but there was no synergism on concomitant administration of either dose of zolmitriptan. Plasma concentrations of zolmitriptan, diazepam, and their respective active metabolites were similar when the two drugs were given alone or in combination. 相似文献
37.
Chest radiographs and chest computed tomography (CT) scans were compared in 203 patients with newly diagnosed Hodgkin disease. The incidence of positive findings was tabulated from six intrathoracic lymph node groups, lung parenchyma, pericardium, pleura, and chest wall. The discordant cases were assessed to determine impact on clinical management. The CT scans provided additional evidence of disease involvement, ranging from 0% to 15% at each of the designated anatomic sites. Treatment was altered in 9.4% of all patients (19 of 203), including 13.8% (nine of 65) of those undergoing radiation therapy alone and 8.2% (ten of 122) of those undergoing combined-modality treatment. We conclude that routine chest CT examinations are valuable in the clinical management of those patients for whom radiation therapy is planned. 相似文献
38.
Cryogenic burns are uncommon. We present two patients who presented to a Regional Burns Unit on consecutive days with almost identical burn injuries caused by exposure to a unique source of sub-zero temperature, the spray from an aerosol deodorant. The clinical features and management of the cases are outlined, and we discuss the mechanism of a cryogenic burn. 相似文献
39.
Ross BD; Jacobson S; Villamil F; Korula J; Kreis R; Ernst T; Shonk T; Moats RA 《Radiology》1994,193(2):457
40.