全文获取类型
收费全文 | 45970篇 |
免费 | 2658篇 |
国内免费 | 100篇 |
专业分类
耳鼻咽喉 | 461篇 |
儿科学 | 1349篇 |
妇产科学 | 938篇 |
基础医学 | 7023篇 |
口腔科学 | 484篇 |
临床医学 | 4141篇 |
内科学 | 10969篇 |
皮肤病学 | 992篇 |
神经病学 | 4264篇 |
特种医学 | 1433篇 |
外国民族医学 | 32篇 |
外科学 | 5911篇 |
综合类 | 143篇 |
一般理论 | 9篇 |
预防医学 | 3362篇 |
眼科学 | 653篇 |
药学 | 3093篇 |
中国医学 | 77篇 |
肿瘤学 | 3394篇 |
出版年
2023年 | 229篇 |
2022年 | 240篇 |
2021年 | 716篇 |
2020年 | 427篇 |
2019年 | 747篇 |
2018年 | 1242篇 |
2017年 | 865篇 |
2016年 | 848篇 |
2015年 | 1048篇 |
2014年 | 1193篇 |
2013年 | 1864篇 |
2012年 | 3002篇 |
2011年 | 3006篇 |
2010年 | 1600篇 |
2009年 | 1338篇 |
2008年 | 2781篇 |
2007年 | 2873篇 |
2006年 | 2643篇 |
2005年 | 2792篇 |
2004年 | 2680篇 |
2003年 | 2470篇 |
2002年 | 2373篇 |
2001年 | 1199篇 |
2000年 | 1241篇 |
1999年 | 1060篇 |
1998年 | 322篇 |
1997年 | 266篇 |
1996年 | 236篇 |
1995年 | 208篇 |
1994年 | 184篇 |
1993年 | 172篇 |
1992年 | 617篇 |
1991年 | 535篇 |
1990年 | 546篇 |
1989年 | 500篇 |
1988年 | 444篇 |
1987年 | 433篇 |
1986年 | 395篇 |
1985年 | 359篇 |
1984年 | 271篇 |
1983年 | 225篇 |
1982年 | 141篇 |
1979年 | 184篇 |
1978年 | 129篇 |
1974年 | 144篇 |
1973年 | 133篇 |
1972年 | 120篇 |
1971年 | 132篇 |
1969年 | 142篇 |
1968年 | 120篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
In brain regions containing noradrenergic (NA) cell bodies or terminals, DSP-4 induces changes in the activity of catecholamine-synthesizing enzymes which suggest that central NA neurons are lesioned by this neurotoxin. In contrast, the lack of change in the same enzymatic activities in an area containing mostly adrenergic (A) neurons (C2 region), favors the hypothesis of a resistance of the A neurons to DSP-4. Furthermore, the enzymatic changes observed in peripheral organs suggest a peripheral activation of the NA cell bodies in response to lesioning of the sympathetic terminals by DSP-4. 相似文献
33.
He Li Lawrence M Schopfer Florian Nachon Marie-Thérèse Froment Patrick Masson Oksana Lockridge 《Toxicological sciences》2007,100(1):136-145
Some organophosphorus compounds are toxic because they inhibit acetylcholinesterase (AChE) by phosphylation of the active site serine, forming a stable conjugate: Ser-O-P(O)-(Y)-(XR) (where X can be O, N, or S and Y can be methyl, OR, or SR). The inhibited enzyme can undergo an aging process, during which the X-R moiety is dealkylated by breaking either the P-X or the X-R bond depending on the specific compound, leading to a nonreactivatable enzyme. Aging mechanisms have been studied primarily using AChE. However, some recent studies have indicated that organophosphate-inhibited butyrylcholinesterase (BChE) may age through an alternative pathway. Our work utilized matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry to study the aging mechanism of human BChE inhibited by dichlorvos, echothiophate, diisopropylfluorophosphate (DFP), isomalathion, soman, sarin, cyclohexyl sarin, VX, and VR. Inhibited BChE was aged in the presence of H2O18 to allow incorporation of (18)O, if cleavage was at the P-X bond. Tryptic-peptide organophosphate conjugates were identified through peptide mass mapping. Our results showed no aging of VX- and VR-treated BChE at 25 degrees C, pH 7.0. However, BChE inhibited by dichlorvos, echothiophate, DFP, soman, sarin, and cyclohexyl sarin aged exclusively through O-C bond cleavage, i.e., the classical X-R scission pathway. In contrast, isomalathion aged through both X-R and P-X pathways; the main aged product resulted from P-S bond cleavage and a minor product resulted from O-C and/or S-C bond cleavage. 相似文献
34.
35.
36.
37.
Laura Cisneros Maria-Carlota Londo?o Carmen Blasco Ramón Bataller Rosa Miquel Miquel Bruguera Pere Ginès Antoni Rimola 《Liver transplantation》2007,13(7):1017-1027
The pathogenic mechanisms of accelerated graft fibrosis in hepatitis C recurrence after liver transplantation (LT) are not well established. The aim of the study was to assess whether a greater activation of hepatic stellate cells (HSC), the major collagen-producing cells in the liver, can occur in these patients as compared to non-LT patients with chronic hepatitis C. We determined the amount of activated HSC by computer-based morphometric analysis of alpha-smooth muscle actin (alphaSMA)-positive cells and the hepatic TGFbeta(1) expression by immunohistochemistry in 46 LT patients with hepatitis C recurrence, 35 non-LT patients with chronic hepatitis C, and 16 controls. Hepatic alphaSMA and TGFbeta(1) expression was higher in LT patients with hepatitis C recurrence than in controls and was correlated with fibrosis stage and progression rate. No significant difference in alphaSMA and TGFbeta(1) expression was observed between LT and non-LT patients with hepatitis C, with the exception of a higher transforming growth factor beta-1 (TGFbeta(1)) expression in non-LT patients in the early stages of fibrosis. LT patients receiving cyclosporine (CsA) or tacrolimus (FK) had a similar fibrosis progression rate and alphaSMA and TGFbeta(1) expression. In conclusion, the accelerated fibrosis observed in LT patients with hepatitis C recurrence does not seem to be related to a greater amount of activated HSC and TGFbeta(1) expression in the grafts of these patients as compared to non-LT patients with chronic hepatitis C. In LT patients, the amount of activated HSC and TGFbeta(1) expression correlated with fibrosis stage and progression, without any apparent influence of the type of calcineurin inhibitor administered. 相似文献
38.
Isabelle Durieu Evelyne Vericel Daniel Guichardant Hubert Roth Jean-Paul Steghens Jocelyne Drai Raphaele Nove Josserand Eric Fontaine Michel Lagarde Gabriel Bellon 《Journal of cystic fibrosis》2007,6(5):320-326
BACKGROUND: An imbalance in the ratio of arachidonic acid and docosahexaenoic acid (DHA) was found in cystic fibrosis (CF) affected tissues and was suggested to promote inflammation. Several studies have shown that the long chain n-3 fatty acids reduced inflammatory activity while others have highlighted prooxidant activity of DHA at high concentrations. The aim of our study was to evaluate the effects of an intravenous fish-oil emulsion enriched with n-3 FA in patients with CF on plasma and platelet FA composition and peroxidation markers. METHODS: 13 patients with CF received one IV emulsion per week of 2 mL/kg fish-oil n-3 emulsion for 12 weeks. RESULTS: There was a significant increase in 20:5 n-3 and 22:6 n-3 platelet FA composition, no variation in 20:4 n-6, a decrease in n-9. There was no variation in plasma FA composition. Specific urinary markers of lipid peroxidation derived from n-3 and n-6 showed a very high level before infusion compared with usual values in healthy subjects which was not affected by treatment. A significant weight loss and a decrease in reduced glutathione were observed in adult patients. CONCLUSIONS: The intravenous administration of n-3 FA in CF patients induced a significant modification in platelet FA composition but no modification of oxidative markers. However, the weight loss and the decreased level in reduced glutathione observed in adult patients may suggest a potential deleterious activity for some patients. Further studies are necessary to determine the optimal dose and route for long chain FA administration required to reach a potential beneficial effect. 相似文献
39.
Nicolas Borenstein Valérie Chetboul Patrick Bruneval Mehrak Hekmati Renaud Tissier Luc Behr Geneviève Derumeaux Didier Montarras 《European journal of cardio-thoracic surgery》2007,31(3):444-451
OBJECTIVE: Cell therapy may be a promising alternative or adjunct to current treatment modalities for ischemic heart failure. But little is known on the impact of myogenic cell transplantation in large animal models of non-ischemic cardiomyopathy. The aim of the present study was to explore whether an ovine model of toxin-induced heart disease could benefit from non-cultured skeletal muscle cell transplantation. METHODS: Sequential intracoronary injections of doxorubicin (0.75 mg/kg) were carried out every 2 weeks until echocardiographic detection of myocardial dysfunction. Sheep were then randomly assigned to either non-cultured cell transplantation (n=8) or placebo injection (n=5). For the cell therapy group, a skeletal muscle biopsy (about 10 g) was explanted from each animal approximately 3h before grafting. After thoracotomy, 20 epicardial injections were carried out. The animals were assessed one last time before sacrifice, 2 months after the thoracotomy. Cells were tracked with cmDiI (red fluorescence) and characterized with immunohistochemistry with monoclonal antibodies to a fast skeletal isoform of myosin heavy chain. RESULTS: Two months after intramyocardial grafting, tissue Doppler imaging and conventional echocardiographic assessment of the groups showed a marked improvement in the non-cultured cell therapy group. Ejection fraction (EF) (p<0.05) as well as systolic endocardial velocities (p<0.01) improved versus the placebo group. CmDiI and skeletal myosin heavy chain expression was detected in all animals at 2 months after implantation confirming engraftment of skeletal muscle cells. CONCLUSIONS: In conclusion, our data indicate that non-cultured muscle cell transplantation is feasible and may translate into a functional benefit in an ovine model of dilated heart failure. 相似文献
40.
Burkhard H. A. von Rahden Brigitte Stigler Wolfgang Weiß Hubert J. Stein 《Journal of gastrointestinal surgery》2007,11(7):945-947
Management of upper gastrointestinal bleeding because of erosion of vessels by esophageal cancer may be challenging. We present
herein the angiographic images of a 49-year-old patient who was admitted with massive bleeding from a tumor-eroded inferior
thyroid artery. Attempts to control the bleeding by means of flexible endoscopy and insertion of a Sengstaken–Blakemore tube
had failed. The diagnosis was impressively demonstrated by multislice computed tomography with intravenous contrast in the
arterial phase and multiplanar reconstructions (computed tomography angiography) and by digital subtraction angiography. The
bleeding was successfully treated with superselective catheterization and coiling of the eroded vessel. 相似文献