全文获取类型
收费全文 | 787篇 |
免费 | 61篇 |
国内免费 | 19篇 |
专业分类
儿科学 | 33篇 |
妇产科学 | 11篇 |
基础医学 | 82篇 |
口腔科学 | 13篇 |
临床医学 | 106篇 |
内科学 | 201篇 |
皮肤病学 | 13篇 |
神经病学 | 22篇 |
特种医学 | 142篇 |
外科学 | 78篇 |
综合类 | 13篇 |
预防医学 | 38篇 |
眼科学 | 9篇 |
药学 | 53篇 |
中国医学 | 2篇 |
肿瘤学 | 51篇 |
出版年
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 12篇 |
2018年 | 15篇 |
2017年 | 9篇 |
2016年 | 10篇 |
2015年 | 16篇 |
2014年 | 23篇 |
2013年 | 31篇 |
2012年 | 27篇 |
2011年 | 39篇 |
2010年 | 26篇 |
2009年 | 34篇 |
2008年 | 26篇 |
2007年 | 39篇 |
2006年 | 42篇 |
2005年 | 44篇 |
2004年 | 34篇 |
2003年 | 35篇 |
2002年 | 22篇 |
2001年 | 22篇 |
2000年 | 10篇 |
1999年 | 25篇 |
1998年 | 37篇 |
1997年 | 42篇 |
1996年 | 36篇 |
1995年 | 21篇 |
1994年 | 18篇 |
1993年 | 17篇 |
1992年 | 3篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 21篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 13篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 12篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1970年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有867条查询结果,搜索用时 0 毫秒
1.
The human visual system is amenable to a number of adaptive processes; one such process, or collection of processes, is the adaptation to blur. Blur adaptation can be observed as an improvement in vision under degraded conditions, and these changes occur relatively rapidly following exposure to blur. The potential important future directions of this research area and the clinical implications of blur adaptation are discussed. 相似文献
2.
Hausegger KA; Cragg AH; Lammer J; Lafer M; Fluckiger F; Klein GE; Sternthal MH; Pilger E 《Radiology》1994,190(1):199
3.
Focal liver lesions: characterization with triphasic spiral CT 总被引:15,自引:1,他引:14
4.
Metabolic adaptation of the chick embryo to chronic hypoxia 总被引:1,自引:0,他引:1
5.
6.
van Asperen J van Tellingen O Schinkel AH Beijnen JH 《The Journal of pharmacology and experimental therapeutics》1999,289(1):329-333
To determine the tissue-specific impact of P-glycoprotein on the accumulation of a substrate drug, we have studied the tissue distribution of vinblastine in mdr1a(-/-) and wild-type mice at approximately similar, relatively low plasma levels. Vinblastine was administered as a 96-h continuous infusion at dose rates of 1 to 10 microgram/h, which were delivered by a s.c.-implanted osmotic pump. Drug concentrations were determined in plasma and tissues by HPLC. In comparison to wild-type mice, 4.4- to 9.6-fold higher drug concentrations were observed in the brains of mdr1a(-/-) mice (p =. 014), whereas a 2-fold increase was found in the heart (p =.014) and the intestinal tissues (p =.028). No or only slight differences were observed in all other tissues. These results indicate that, except for the brain and, to a lesser extent, the heart and the intestinal tissues, P-glycoprotein does not protect individual organs against vinblastine. Given its polarized cell-specific and organ-specific distribution and its affinity for a broad range of compounds, it is suggested that P-glycoprotein has mainly evolved to provide a general protection of the complete organism against potentially toxic substrates by inhibiting their uptake and by mediating their transport from the internal to the external environment. For the clinical application of reversal agents, these data indicate that, in general, a blockade of endogenous P-glycoprotein will probably not result in an increased accumulation of the coadministered anticancer drug in complete organs, but, possibly, only in classes of cells making up a fraction of an organ. 相似文献
7.
Schinkel AH 《Advanced drug delivery reviews》1999,36(2-3):179-194
The blood-brain barrier is a major impediment to the entry of many therapeutic drugs into the brain. P-Glycoprotein is an ATP-dependent drug transport protein that is predominantly found in the apical membranes of a number of epithelial cell types in the body, including the blood luminal membrane of the brain capillary endothelial cells that make up the blood-brain barrier. Since P-glycoprotein can actively transport a huge variety of hydrophobic amphipathic drugs out of the cell, it was hypothesized that it might be responsible for the very poor penetration of many relatively large (>400 Da) hydrophobic drugs in the brain, by performing active back-transport of these drugs to the blood. Extensive experiments with in vitro models and with knockout mice lacking blood-brain barrier P-glycoprotein or other animal models treated with blockers of P-glycoprotein have fully confirmed this hypothesis. Absence of functional P-glycoprotein in the blood-brain barrier leads to highly increased brain penetration of a number of important drugs. Depending on the pharmacological target of these drugs in the central nervous system (CNS), this can result in dramatically increased neurotoxicity, or fundamentally altered pharmacological effects of the drug. Given the variety of drugs affected by P-glycoprotein transport, it may be of tremendous therapeutic value to apply these insights to the development of drugs that should have either very poor or very good brain penetration, whichever is preferred for pharmacotherapeutic purposes. The clinical application of P-glycoprotein blockers should also be considered in order to improve the blood-brain barrier permeability of certain drugs that currently display insufficient brain penetration for effective therapy. 相似文献
8.
The vasa vasorum and angioplasty 总被引:2,自引:0,他引:2
Cragg AH; Einzig S; Rysavy JA; Castaneda-Zuniga WR; Borgwardt B; Amplatz K 《Radiology》1983,148(1):75-80
Interruption of flow in the vasa vasorum may lead to medial necrosis and aneurysm formation. The purpose of this study was to determine whether angioplasty produces significant alterations in the morphology or blood flow of the vasa vasorum of the dilated artery. The morphology of the canine vasa vasorum was studied before and after angioplasty; in a separate experiment vessel wall blood flow (VWBF) in canine carotid arteries was measured after angioplasty to determine whether physiologic regulation of the blood flow was disrupted by arterial dilation. No morphologic changes could be demonstrated in the vasa vasorum of the dilated artery; however, VWBF was increased by 1194 +/- 215% (mean +/- standard error, p less than 0.01) between 90 and 120 minutes after angioplasty. VWBF in the adjacent nondilated arterial segment was also increased (720 +/- 177% between 10-30 minutes, p less than 0.01) but returned toward normal after 60 minutes. Adenosine caused a "paradoxical" decrease in VWBF (p less than 0.05) of the dilated arterial segment while causing increased VWBF (p less than 0.05) in the thoracic aorta. Angioplasty appears to produce persistent hyperemia in the dilated arterial wall. A paradoxical response to adenosine suggests that vasa vasorum in the dilated arterial segment are maximally vasodilated. This may be due to mechanical disruption of vasomotor tone or to release of vasoactive substances. 相似文献
9.
WG Mitchell H Lynn JF Bale MA Maeder SM Donfield B Garg AH Tilton JK Willis TP Bohan 《Pediatrics》1997,100(5):817-824
BACKGROUND: Boys and young men with hemophilia treated with factor infusions before 1985 had a substantial risk of acquiring the human immunodeficiency virus (HIV) and the acquired immunodeficiency syndrome. This study was designed to assess the effects of HIV and hemophilia per se on neurological function in a large cohort of subjects with hemophilia, and to investigate the relationships between neurological disease and death during follow-up. METHODS: Three hundred thirty-three boys and young men (207 HIV seropositive and 126 HIV seronegative) were evaluated longitudinally in a multicenter, multidisciplinary study. Neurological history and examination were conducted at baseline and annually for 4 years. The relationship between neurological variables, HIV serostatus, CD4+ cell counts, and vital status at the conclusion of the study was examined using logistic regression models. RESULTS: The risks of nonhemophilia-associated muscle atrophy, behavior change, and gait disturbance increased with time in immune compromised HIV-seropositive subjects compared with HIV seronegative or immunologically stable HIV-seropositive subjects. The risk of behavior change in immune compromised HIV-seropositive hemophiliacs, for example, rose to 60% by year 4 versus 10% to 17% for the other study groups. Forty-five subjects (13.5%), all of whom were HIV seropositive, died by year 4. Subjects who died had had increased risks of hyperreflexia, nonhemophilia-associated muscle atrophy, and behavior change. CONCLUSIONS: These results indicate that immune compromised, HIV-seropositive hemophiliacs have high rates of neurological abnormalities over time and that neurological abnormalities were common among subjects who later died. By contrast, immunologically stable HIV-seropositive subjects did not differ from the HIV-seronegative participants. Hemophilia per se was associated with progressive abnormalities of gait, coordination, and motor function. 相似文献
10.
氯地滴眼液的含量测定 总被引:4,自引:0,他引:4
目的:采用HPLC法测定氯地滴眼液中氯霉素和地塞米松磷酸钠的含量。方法:色谱分析条件:ODS柱作分析柱,流动相为甲醇/水体系,0 ̄8min使用40%甲醇,8 ̄16min使用60%甲醇,流速1ml/min,0 ̄9min240nm紫外检测,:二组分分离良好。各组各组性关系良好,平均回收率氯霉素99.8%(RSD=1.2%,n=5),地塞米松磷酸钠99.4%(RSD=0.7%,n=5),结论:该法用于氯 相似文献