全文获取类型
收费全文 | 3368篇 |
免费 | 187篇 |
国内免费 | 76篇 |
专业分类
耳鼻咽喉 | 76篇 |
儿科学 | 137篇 |
妇产科学 | 32篇 |
基础医学 | 488篇 |
口腔科学 | 93篇 |
临床医学 | 411篇 |
内科学 | 815篇 |
皮肤病学 | 53篇 |
神经病学 | 229篇 |
特种医学 | 346篇 |
外科学 | 328篇 |
综合类 | 35篇 |
一般理论 | 2篇 |
预防医学 | 126篇 |
眼科学 | 33篇 |
药学 | 245篇 |
中国医学 | 2篇 |
肿瘤学 | 180篇 |
出版年
2023年 | 16篇 |
2022年 | 29篇 |
2021年 | 53篇 |
2020年 | 32篇 |
2019年 | 55篇 |
2018年 | 47篇 |
2017年 | 37篇 |
2016年 | 41篇 |
2015年 | 54篇 |
2014年 | 79篇 |
2013年 | 106篇 |
2012年 | 131篇 |
2011年 | 142篇 |
2010年 | 86篇 |
2009年 | 99篇 |
2008年 | 115篇 |
2007年 | 180篇 |
2006年 | 151篇 |
2005年 | 127篇 |
2004年 | 111篇 |
2003年 | 102篇 |
2002年 | 92篇 |
2001年 | 109篇 |
2000年 | 125篇 |
1999年 | 97篇 |
1998年 | 96篇 |
1997年 | 107篇 |
1996年 | 98篇 |
1995年 | 87篇 |
1994年 | 63篇 |
1993年 | 71篇 |
1992年 | 61篇 |
1991年 | 72篇 |
1990年 | 63篇 |
1989年 | 88篇 |
1988年 | 71篇 |
1987年 | 88篇 |
1986年 | 63篇 |
1985年 | 64篇 |
1984年 | 50篇 |
1983年 | 36篇 |
1982年 | 32篇 |
1981年 | 25篇 |
1980年 | 27篇 |
1979年 | 13篇 |
1978年 | 16篇 |
1977年 | 16篇 |
1976年 | 17篇 |
1975年 | 17篇 |
1968年 | 9篇 |
排序方式: 共有3631条查询结果,搜索用时 15 毫秒
1.
2.
We have studied the effects of semi-synthetic diets rich in either n-9 (olive oil, OO) or n-6 (corn oil, CO), or n-3 (fish oil, FO, as MaxEPA) fatty acids on the levels of major PUFA in platelet lipids, on the generation of inositol phosphates by [3H]inositol labelled platelets after stimulation with thrombin and of thromboxane B2 (TxB2) by platelet rich plasma (PRP) after stimulation with collagen. The predicted elevations of oleic (OA), linoleic (LA) and eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids were observed in platelet lipids of each animal group, but in the MaxEPA fed group accumulation of EPA was associated with depletion of linoleic acid (LA) rather than of arachidonic acid (AA). Basal levels of inositol-tris-phosphate (IP3) in platelets were lowest in the OO group and highest in the CO group, whereas the increment after thrombin stimulation (1 unit/ml NIH) was maximal in the OO group and minimal in the FO group. Instead, when generation of TxB2 by stimulated platelets was evaluated, no appreciable difference among the various groups could be detected, in accordance with the limited modifications of platelet AA content induced by the diets. The overall data indicate that dietary fatty acids modulate the pathway of inositol phosphate generation in rabbit platelets, independently of modifications of TxB2 production. 相似文献
3.
Lupus anticoagulant IgG's (LA) are not directed to phospholipids only, but to a complex of lipid-bound human prothrombin. 总被引:25,自引:0,他引:25
Plasmas from 16 patients that were found to be positive both for anticardiolipin antibodies (ACA) and lupus anticoagulants (LA) were incubated with liposomes that contained anionic phospholipids. In 11 of these plasmas, ACA could be cosedimented with the liposomes in a dose-dependent manner, whereas LA activity of the remaining supernatant was unaffected. LA activity of purified total IgG from 6 patients was measured in three different coagulation tests, using normal plasmas from different species. Prolongation of the aPTT, KCT and dRVV clotting times was observed only with normal plasma from human origin, not with bovine, rat or sheep plasma. Highly purified coagulation factors Xa, Va and prothrombin, both of human and bovine origin, were used to establish for two patient IgG's the effect of LA on the rate of thrombin formation in the presence and absence of lipid vesicles composed of 20 mole% phosphatidylserine and 80 mole% phosphatidylcholine. A strong and dose dependent inhibition by LA was observed only when human prothrombin was used as substrate in the prothrombinase complex in the presence of lipids. No inhibition was found when bovine prothrombin was used as substrate. The inhibitory effect observed in the presence of human prothrombin was independent of the source of factors Xa and Va, and was not found in the absence of lipid. Preliminary binding studies suggest that LA only associate with a lipid surface, provided that human prothrombin and calcium ions are present. These data indicate that LA are not directed to phospholipids alone, but presumably recognize an epitope which becomes exposed upon Ca(2+)-mediated binding of human prothrombin to phospholipids. 相似文献
4.
5.
We studied the significance of free erythrocyte protoporphyrin (FEP) in relation to iron status, aluminum levels and anemia in uremic patients on chronic dialysis. All but 1 patient showed high FEP values closely related to the degree of anemia. Increased FEP levels are due to a defective heme synthesis, not related to iron deficiency or aluminum overload. Treatment of anemia with recombinant human erythropoietin reduced FEP values. We therefore hypothesize that recombinant human erythropoietin ameliorates an enzymatic defect in heme synthesis. 相似文献
6.
7.
8.
G Galella L Medini E Stragliotto P Stefanini P Rise E Tremoli C Galli 《Biochemical pharmacology》1992,44(4):715-720
Interleukin-1 (IL-1) can initiate the synthesis of prostaglandins which in turn act as endogenous modulators of IL-1 production. The human monocyte/macrophage synthesizes various eicosanoids through the activation of the cellular phospholipase system. Cell stimulation results in the activation of phospholipase A2 (PLA2) whose major substrate is phosphatidylcholine (PC) and the release of the eicosanoid precursor arachidonic acid (AA) from PC. Another pathway is the stimulation of a phospholipase C (PLC) mainly active on phosphoinositides and the resulting formation of inositol phosphates (IPs) and diacylglycerol (DAG). Phospholipids other than phosphoinositides can also be hydrolysed by PLC to give rise to DAG. Studies have shown that IL-1 does not activate the IP pathway, but it primarily stimulates a PLC linked to phosphatidylethanolamine in cultured rat mesangial cells, and a PLC linked to PC in Jurkart cells. We have stimulated human monocytes with IL-1 and calcium ionophore A23187 and we have observed their effect on the phospholipase system. The results indicate that IL-1 does not activate the formation of IPs in cells labeled with [3H]myo-inositol. In contrast, in cells labeled with [3H]AA, IL-1 causes the formation of DAG associated with the hydrolysis of PC. Moreover, after stimulation with IL-1 there is no accumulation of free AA which would indicate that there has been no activation of PLA2, which occurs instead with A23187 stimulation. These data suggest that, in monocytes, IL-1 does not directly stimulate a PLA2 or a PLC active on phosphatidylinositol; instead it primarily stimulates a PLC active on PC. 相似文献
9.
10.