全文获取类型
收费全文 | 445篇 |
免费 | 50篇 |
国内免费 | 20篇 |
专业分类
儿科学 | 7篇 |
妇产科学 | 9篇 |
基础医学 | 55篇 |
口腔科学 | 7篇 |
临床医学 | 26篇 |
内科学 | 30篇 |
皮肤病学 | 10篇 |
神经病学 | 21篇 |
特种医学 | 7篇 |
外科学 | 24篇 |
综合类 | 97篇 |
预防医学 | 29篇 |
眼科学 | 10篇 |
药学 | 41篇 |
中国医学 | 126篇 |
肿瘤学 | 16篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 10篇 |
2021年 | 27篇 |
2020年 | 24篇 |
2019年 | 13篇 |
2018年 | 10篇 |
2017年 | 19篇 |
2016年 | 21篇 |
2015年 | 24篇 |
2014年 | 29篇 |
2013年 | 28篇 |
2012年 | 32篇 |
2011年 | 38篇 |
2010年 | 29篇 |
2009年 | 16篇 |
2008年 | 11篇 |
2007年 | 20篇 |
2006年 | 16篇 |
2005年 | 15篇 |
2004年 | 11篇 |
2003年 | 6篇 |
2002年 | 10篇 |
2001年 | 11篇 |
2000年 | 12篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有515条查询结果,搜索用时 281 毫秒
31.
人精子染色体离体测试系统中S9混合物的应用 总被引:2,自引:1,他引:2
在未加和加入体外代谢激活体系S9混合物2种情况下,将人精子用最终浓度分别为20、40、60μg/ml环磷酰胺处理3.5h,然后与去透明带地鼠卵进行异种体外受精,继而制备精子染色体进行核型分析。在未加S9混合物组,环磷酰胺3种剂量处理的染色体结构畸变精子率依次为10%、12%、10%;断裂均数依次为0.22、0.14、0.20;在加入S9混合物组,畸变精子率依次为18%、24%、32%;断裂均数依次为0.38、0.78、1.64.2组间畸变精子率和断裂均数差异显著(P<0.05)。加入S9混合物组,环磷酰胺3种剂量处理的畸变精子率和断裂均数都高于空白对照组(10%,0.12%),其差异具有统计学意义且畸变精子率和断裂均数随着环磷酰胺剂量增加而增高。本研究结果表明,人精子染色体离体测试系统可以用来检测原诱变剂对人精子中遗传物质的诱变效应。但原诱变剂必须经S9混合物代谢成激活型。 相似文献
32.
Histamine inhibits in vitro human neutrophil chemotaxis and T-lymphocyte proliferation via H2 receptors. The aim of this study was to verify these inhibitory effects of histamine in man in vivo. Healthy volunteers were challenged with histamine by intravenous (1 mg), subcutaneous (1 mg) and inhalatory (2.4 mg) routes. Venous blood was taken before and at different times after challenge. Neutrophil chemotaxis was studied by the Boyden assay and T-lymphocyte proliferation by counting H3-thymidine incorporation in cultured mononuclear cells. Plasma histamine was measured by radioimmunoassay. Histamine infusion caused transient systemic symptoms as well as a significant decrease of neutrophil chemotaxis (mean - 26% +/- 6) and of PHA-pulsed T-lymphocyte proliferation (mean - 16% +/- 6) 4 h after histamine challenge. Subcutaneous injection of histamine caused only a significant decrease of neutrophil chemotaxis (mean - 24% +/- 15) 4 h after injection. Histamine inhalation was well tolerated and caused a significant depression of neutrophil chemotaxis (mean - 40% +/- 15) and of T-lymphocyte proliferation (mean - 27% +/- 6) 2 and 4 h after the challenge. Histamine challenges were always accompanied by a rapid and transient rise in plasma histamine. Inhalation of an H2 agonist (impromidine) but not of an H1 agonist (betahistine) caused a decrease of neutrophil chemotaxis and of T-lymphocyte proliferation. Oral pretreatment with an H2 antagonist (cimetidine) before histamine inhalation prevented histamine-induced decrease of neutrophil chemotaxis and T-lymphocyte proliferation, whereas astemizole, an H1 antagonist, had no effect. In conclusion, during the few hours following administration, exogenous histamine in man causes a depression of neutrophil chemotaxis and T-lymphocyte proliferation via H2 receptors.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
33.
O. V. Zhuk N. Ya. Golovenko V. G. Zin'kovskii 《Bulletin of experimental biology and medicine》1988,105(5):631-634
Department of Physicochemical Pharmacology, A. V. Bogatskii Physicochemical Institute, Academy of Sciences of the Ukrainian SSR, Odessa. (Presented by Academician of the Academy of Medical Sciences of the USSR A. V. Val'dman.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 105, No. 5, pp. 529–531, May, 1988. 相似文献
34.
Tanaka A Yoshizawa M Abe K Takeda H Yambe T Nitta S Abe Y Chinzei T Imachi K 《Artificial organs》2004,28(1):109-114
It is desirable for the dynamic behavior of the drive rate of the artificial heart to be as similar as possible to that of the recipient's heart rate (HR) before implantation. This requires a model which can simulate the behavior of HR on the basis of only the information measured with the limited number of approvable implanted sensors. This article provides a linear time series model for explaining the behavior of HR only with aortic pressure and right atrial pressure. This could be obtained from open-loop analysis using a total artificial heart, which was introduced for measuring HR in vivo and for eliminating its effect on blood pressure. The model was identified in a goat equipped with a special biventricular assist device called the effectively total artificial heart (ETAH). The ETAH was introduced to make an open loop and awake situation in the animal with almost intact autonomic nerves, which could enhance the accuracy and reliability of the identification of the model. The adequacy of the proposed model was ascertained in several data sets measured in two goats, which were different from the data set used for identification. Most of the mean estimation errors were less than 3 beats/min and auto-correlation analysis showed approvable statistical appropriateness. However, it was clarified through comparison with the 1/R control method that the proposed model has a few problems still to be solved before its future implementation as an automatic controller of the TAH. 相似文献
35.
The age-related changes in the incidence of 'natural' anti-sperm antibodies suggest they are not auto-/isoantibodies 总被引:1,自引:0,他引:1
Kalaydjiev SK Dimitrova DK Trifonova NL Fichorova RN Masharova NG Raicheva YN Simeonova MN Todorova EI Todorov VI Nakov LS 《American journal of reproductive immunology (New York, N.Y. : 1989)》2002,47(2):65-71
PROBLEM: Establishing the age-dependent patterns of sperm antibody levels among normal humans. METHODS OF STUDY: Sera samples from 498 healthy subjects aged 0-97 years - 246 males and 252 females - were tested by the gelatin agglutination test of Kibrick, tray agglutination test of Friberg, sperm immobilization test of Isojima and enzyme-linked immunosorbent assay (ELISA). RESULTS: We found a significant increase in the level of sperm agglutinins after 40 years, which decreased after 88 years. The antibodies detected by ELISA were the highest among prepubertal subjects and also declined with aging. No age-dependent changes were established for the sperm immobilizins. With few exceptions, there were no significant differences between male and female sera, as well as between sera of newborn and their mothers. CONCLUSIONS: These data are similar to those established for the age-dependent changes of antibodies towards exogenous antigens, suggesting that the 'naturally occurring' antibodies against human spermatozoa are not auto-/isoantibodies. 相似文献
36.
To avoid using sensors with low biocompatibility and low durability in implantable total artificial heart (TAH) systems, the authors previously proposed a new method for estimating instantaneous values of flow rate and pressure head on the basis of voltage, current, and rotational speed in a motor driven centrifugal pump. The previous in vitro experiments showed that the proposed estimator could automatically compensate for the effect of the change in blood viscosity on the estimation accuracy by employing two kinds of autoregressive exogenous models. In this study, validity and reliability of this estimation method were ascertained in an acute animal experiment. In the experiment, two centrifugal blood pumps were implanted into an adult goat as a total artificial heart. Results of estimation were compared with true values when blood viscosity was changed by injecting physiological saline. The results indicated that the system could successfully estimate pressure head by compensating the change of viscosity, although the estimation accuracy of the in vivo estimation was not so high as that of the previous in vitro tests. 相似文献
37.
38.
AIM:To compare the effects of liposomes and glyco-poly-L-lysine on liver targeted uptake and expression of plasmid in rat liver.METHODS:After binding with lipofectamine or galactose-terminal glyco-poly-l-lysine, the plasmid could be expressed in eukaryotic cells when injected in to Wistar rats by intravenous route. At different time intervals after the injection, the distribution and expression of the plasmid in liver of rats were observed and compared using in situ hybridization and immunohistochemistry.RESULTS:The expression of the plasmidbinding to liposomes or G-PLL cou ld be markedly observed 24 h later, and began to decrease one week later,but it still could be observed up to three weeks.Both liposomes and G-PLL coul d deliver the plasmid to the liver effectively, but the effect of the latter was better than the former concerning the distribution and expression of the plasmid targeted uptake in the liver. 相似文献
39.
40.
心肌纤维化动物模型作为研究治疗心肌纤维化的病程发展、药物疗效和治疗手段的重要载体,在整个心肌纤维化的研究中起着重要作用。本文对常见的压力超负荷、外源性活性因子诱导和缺血诱导心肌纤维化模型方法进行汇总,对各类模型的造模方法、作用机制及优缺点进行阐述,希望为创建并完善更加准确的心肌纤维化模型提供参考。 相似文献