全文获取类型
收费全文 | 24156篇 |
免费 | 1353篇 |
国内免费 | 949篇 |
专业分类
耳鼻咽喉 | 117篇 |
儿科学 | 371篇 |
妇产科学 | 199篇 |
基础医学 | 1395篇 |
口腔科学 | 173篇 |
临床医学 | 2029篇 |
内科学 | 3746篇 |
皮肤病学 | 115篇 |
神经病学 | 582篇 |
特种医学 | 363篇 |
外国民族医学 | 1篇 |
外科学 | 6615篇 |
综合类 | 2987篇 |
预防医学 | 1864篇 |
眼科学 | 133篇 |
药学 | 2679篇 |
22篇 | |
中国医学 | 2598篇 |
肿瘤学 | 469篇 |
出版年
2024年 | 76篇 |
2023年 | 639篇 |
2022年 | 1012篇 |
2021年 | 1396篇 |
2020年 | 1320篇 |
2019年 | 1090篇 |
2018年 | 1201篇 |
2017年 | 1147篇 |
2016年 | 773篇 |
2015年 | 749篇 |
2014年 | 1728篇 |
2013年 | 2031篇 |
2012年 | 1431篇 |
2011年 | 1539篇 |
2010年 | 1085篇 |
2009年 | 928篇 |
2008年 | 1006篇 |
2007年 | 997篇 |
2006年 | 760篇 |
2005年 | 662篇 |
2004年 | 517篇 |
2003年 | 466篇 |
2002年 | 398篇 |
2001年 | 320篇 |
2000年 | 282篇 |
1999年 | 281篇 |
1998年 | 234篇 |
1997年 | 237篇 |
1996年 | 196篇 |
1995年 | 191篇 |
1994年 | 180篇 |
1993年 | 148篇 |
1992年 | 131篇 |
1991年 | 120篇 |
1990年 | 116篇 |
1989年 | 103篇 |
1988年 | 105篇 |
1987年 | 100篇 |
1986年 | 71篇 |
1985年 | 91篇 |
1984年 | 91篇 |
1983年 | 69篇 |
1982年 | 74篇 |
1981年 | 60篇 |
1980年 | 60篇 |
1979年 | 45篇 |
1978年 | 38篇 |
1977年 | 40篇 |
1976年 | 39篇 |
1975年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Capacitation-dependent concentration of lipid rafts in the apical ridge head area of porcine sperm cells 总被引:3,自引:0,他引:3
van Gestel RA Brewis IA Ashton PR Helms JB Brouwers JF Gadella BM 《Molecular human reproduction》2005,11(8):583-590
Lipid architecture of the plasma membrane plays an important role in the capacitation process of the sperm cell. During this process, an increase in membrane fluidity takes place, which coincides with a redistribution of cholesterol to the apical region of the head plasma membrane and subsequently an efflux of cholesterol. Cholesterol is also a major player in the formation of lipid rafts or microdomains in the membrane. Lipid rafts favour specific protein-protein interactions by concentrating certain proteins in these microdomains while excluding others. In this study, we investigated the organization of lipid rafts during in vitro capacitation of boar sperm cells. We report on the presence of the lipid raft-specific proteins caveolin-1 and flotillin-1 in sperm cells. Capacitation induced a change in membrane distribution of these proteins. Lipid analysis on detergent-resistant membranes (DRMs) of sperm cells indicated that capacitation induces a lipid raft concentration rather than a disintegration of lipid rafts, because the total amount of lipid in the DRM fraction remained unaltered. Using a proteomic approach, we identified several major DRM proteins, including proteins involved in capacitation-dependent processes and zona pellucida binding. Our data indicate that sperm raft reorganization may facilitate capacitation-specific signalling events and binding to the zona pellucida. 相似文献
72.
健康成人血液流变学与血脂相关性的实验研究 总被引:1,自引:0,他引:1
目的:研究健康成人血液流变学指标与血脂之间的相关性。方法:抽取西安市某单位健康查体人群各项检查结果齐全的资料117例,其中男性79例,女性38例,将采集的数据进行统计分析。结果:男性和女性之间,TG、HBV、LBV、HRV、LRV、CV、CY均有显著差异(P〈0.05);女性资料中,血脂指标与血液流变学指标的相关性无统计学意义(P〉0.05);男性资料中,血液流变学指标与血脂指标有相关性(P〈0.05)。结论:控制血液粘度和血脂水平是防止和减低心脑血管疾病发生的重要环节。 相似文献
73.
74.
S. A. Kurilovich E. V. Pozdeeva A. P. Serdyuk I. O. Svetlova Yu. A. Shakhov 《Bulletin of experimental biology and medicine》1990,110(6):1660-1663
Institute of Therapy, Siberian Branch, Academy of Medical Sciences of the USSR, Novosibirsk. All-Union Preventive Medicine Research Center, Ministry of Health of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR Yu. P. Nikitin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 110, No. 12, pp. 611–613, December, 1990. 相似文献
75.
Sh. K. Kurbanov Ch. R. Alimhodzhaeva 《Bulletin of experimental biology and medicine》1979,87(5):421-423
The enzyme spectrum of pancreatic homogenate was studied in acute experiments on male albino rats during adaptation for 30 days to muscular exertion (forced swimming in water at a temperature of 32±1°C), heat (hyperthermia to 40–41°C), and cold (cooling to 3–4°C) for 3 h. The initial periods of adaptation to these factors (second-twelfth day) were shown to be characterized by a considerable decrease in activity of all the enzymes studied, but later, with adaptation of the animals to these factors, enzyme activity was restored to its original level (18th–24th day), and remained more or less constant until the end of the experiment (30th day). It is suggested that changes in the enzyme spectrum of the pancreas are brought about through the participation of the hypothalamo-hypophyseo-adrenal system in accordance with the principle of the general adaptation syndrome.Laboratory of the Physiology of Digestion and Laboratory of General Physiology, Institute of Physiology, Academy of Sciences of the Uzbek SSR, Tashkent. (Presented by Academician of the Academy of Sciences of the USSR O. G. Gazenko.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 5, pp. 412–414, May, 1979. 相似文献
76.
G Hagner 《Immunobiology》1984,167(4):389-397
The erythroleukemic K562 cell line was induced to erythroid differentiation by a variety of agents, including hemin, bleomycin, and cytosine arabinoside. The sensitivity of induced cells to binding and lysis by non-sensitized peripheral blood mononuclear cells (MNC) in agarose was studied in relation to the target cell division rate. Differentiated K562 cells formed a lower proportion of conjugates with MNC, when compared with non-induced controls. The reduction correlated significantly with the level of differentiation, irrespective of the inducer and the proliferative status. The differentiation-induced alterations of lysis, however, were strongly influenced by the modification of target cell growth rate which was caused by the differentiating agent. These data suggest that target cell differentiation has distinct effects upon the steps of recognition and lysis by natural killer cells. 相似文献
77.
张渡淮 《生物医学工程学杂志》1995,12(1):64-66
伊·普利高津的耗散结构理论中,有一个著名的总熵变公式ds=dse+dsi把上述公式用于人体研究,国内外尚未见报导。在前人对人体热力学系统研究的基础上,本文建立了一个人体熵流的数学模型,为进一步展开研究,提供了有力工具并奠定了可靠的理论基础。 相似文献
78.
Bottini N Otsu A Borgiani P Saccucci P Stefanini L Greco E Fontana L Hopkins JM Mao XQ 《Clinical genetics》2003,63(3):228-231
Protein tyrosine phosphatases (PTPases) have recently been recognized as important modulators of various signal transduction pathways in immune cells. Genetic polymorphisms have been described in genes codifying for members of this family of enzymes, and the genetics of PTPases is predicted to play an important role in the etiology of immune diseases and of their clinical variability. The low molecular weight protein tyrosine phosphatase (ACP1 or LMPTP) is one of the few PTPases with a known genetic polymorphism, and has been proposed to be associated with atopic dermatitis in a small sample from an Italian population. In this paper we describe the association of the ACP1 polymorphism with total IgE levels in two independent samples from English and Italian populations. In both the samples the mean value of serum IgE is lower among subjects carrying the BC genotype than in other ACP1 genotypes. The BC genotype is associated with the highest total ACP1 enzymatic activity. Our data suggest that one or both of the ACP1 isoforms exert an inhibitory role on some signal transduction pathway relevant for IgE hyperproduction. 相似文献
79.
A. A. Nikiforova A. A. Kuz'min W. Richter 《Bulletin of experimental biology and medicine》1995,120(3):962-964
In vitro experiments show that sodium citrate in a final concentration of 130 mM induces a 4- to 5-fold increase in the activity of
lecithin-cholesterol acyltransferase. A parallel determination of the blood content of primary products of lipid peroxidation
reveals a 20–30% decrease in diene and triene conjugates and lipid hydroperoxides.
Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N
o
9, pp. 323–325, September, 1995
Presented by A. N. Klimov, Member of the Russian Academy of Medical Sciences 相似文献
80.
One hundred and sixty-three healthy Chinese subjects of both sexes were studied for serum paraoxonase (PON) polymorphism, and levels of lipids and apolipoproteins in order to examine effects of PON alleles on these parameters. The level of serum triglyceride was significantly higher in high activity allele (PON*B) compared with that in low activity allele (PON*A) in both sexes (P less than 0.01). The subjects with PON A had significantly higher LDL cholesterol (P less than 0.05) and lower Apo A-II and ApoB levels. The influence of serum paraoxonase on serum lipids was estimated further by Spearman's rank correlation. In the males, there was a significant negative correlation of serum paraoxonase activity with total (P less than 0.05) and LDL (P less than 0.01) cholesterol levels, and positive correlation with HDL cholesterol and Apo A-II levels (P less than 0.05). Serum paraoxonase activity had a high positive correlation with serum triglyceride levels in both sexes (P less than 0.001). Serum ApoB level had a positive correlation with the enzyme activity only in females (P less than 0.01). The allelic effect of PON on these parameters was studied by multiple regression analysis. The high activity allele (PON*B) was associated with higher serum triglyceride level (P less than 0.001) and ApoB (P less than 0.001), while it had lowering influence on total cholesterol (P less than 0.05) and LDL cholesterol (P less than 0.005) in men. The average allelic effect of PON was found to be about 22% for serum triglycerides, 11% for LDL cholesterol, 14% for Apo A-II and 19% for Apo B in the present study. This study suggests a possible significant role of serum paraoxonase alleles in the metabolism of serum lipids and apolipoproteins. 相似文献