全文获取类型
收费全文 | 713篇 |
免费 | 45篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 33篇 |
妇产科学 | 51篇 |
基础医学 | 178篇 |
口腔科学 | 14篇 |
临床医学 | 41篇 |
内科学 | 92篇 |
皮肤病学 | 17篇 |
神经病学 | 43篇 |
特种医学 | 11篇 |
外科学 | 100篇 |
综合类 | 45篇 |
预防医学 | 30篇 |
眼科学 | 9篇 |
药学 | 40篇 |
中国医学 | 6篇 |
肿瘤学 | 55篇 |
出版年
2023年 | 20篇 |
2022年 | 32篇 |
2021年 | 27篇 |
2020年 | 24篇 |
2019年 | 78篇 |
2018年 | 47篇 |
2017年 | 32篇 |
2016年 | 20篇 |
2015年 | 21篇 |
2014年 | 26篇 |
2013年 | 22篇 |
2012年 | 29篇 |
2011年 | 34篇 |
2010年 | 21篇 |
2009年 | 23篇 |
2008年 | 30篇 |
2007年 | 13篇 |
2006年 | 29篇 |
2005年 | 28篇 |
2004年 | 20篇 |
2003年 | 23篇 |
2002年 | 10篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 9篇 |
1997年 | 8篇 |
1996年 | 14篇 |
1995年 | 8篇 |
1994年 | 12篇 |
1993年 | 6篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 1篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有768条查询结果,搜索用时 15 毫秒
1.
2.
雄激素不敏感综合征(androgen insensitivity syndrome,AIS)又称为睾丸女性化综合征(testicular feminization syndrome,TFS),是一种X连锁遗传病,是男性假两性畸形中较常见的类型,可分为完全型AIS和不完全型AIS,其原因主要是雄激素受体(androgen receptor,AR)基因的突变导致其对雄激素产生抵抗和不应答。本文回顾南京医科大学附属妇产医院2例CAIS患者的临床资料及诊疗过程,以期能进一步提高对该病的认知及诊治水平。 相似文献
3.
4例SRY阳性的46,XX男性综合征患者临床及细胞分子遗传学研究 总被引:6,自引:4,他引:2
目的:探讨SRY阳性的46,XX男性综合征患者的临床及细胞分子遗传学特征。方法:分析4例SRY阳性的46,XX男性综合征患者的临床特点,并进行染色体核型分析、荧光原位杂交(FISH)、SRY基因检测、Y染色体微缺失等细胞和分子遗传学检测。结果:4例患者社会性别均为男性,身材低于正常男性均值。均因不育就诊,双侧睾丸体积小、质地软,精液检查均为无精子症。阴茎发育正常。性激素检查示高促性腺激素性性腺功能不全。染色体核型均为46,XX,Y染色体微缺失检测示AZFa,b,c区域均缺失。SRY基因均存在,FISH结果3例患者显示SRY基因易位于X染色体短臂。结论:SRY阳性的46,XX男性综合征患者常为男性表型,但睾丸发育不良,多伴有身材矮小和不育。患者的男性表型是由于基因组中存在SRY基因。无精子表型是由于缺失AZF。Y染色体长臂上可能存在与身高相关的基因。深入进行细胞、分子遗传学研究有助于揭示46,XX男性综合征基因型-表型的关系。 相似文献
4.
用高效液相色谱跟踪2-甲基-7-亚甲基-1,4,6-三氧螺[4,4]壬烷(MMTN)与丙烯腈(AN),丙烯酸甲酯(MA)的共聚合反应。根据Lowry-Meyer共聚积分方程式,采用插值法进行数据拟合测定单体的竞聚率。对于体系MMTN(M_1)-AN(M_2),r_1=0.048;r_2=0.213;MMTN(M_1)-MA(M_2)r_1=0.025,r_2=0.764。说明两组共聚体系均有较强的交替共聚趋势。 相似文献
5.
近年证明SRY男性性基因是性别决定关键。SRY突变能引起男性性异常。46,XY性腺发育不全(或XY女性)系SRY基因突变所致,并有高发性腺肿瘤特点。SRY突变有多种类型;本研究检测一家庭集聚性XY女性高发肿瘤成员有个SRY基因缺失。结合细胞遗传学和病理学检查结果,对XY女性性腺癌变机理提出了推测。 相似文献
6.
Slices from rat midbrain containing the raphe nuclei and from hippocampus were prepared, loaded with [3H]5-HT and superfused and the resting and the electrically stimulated [3H]5-HT release was measured. The 5-HT3 receptor agonist 2-methyl-5-HT (1 to 10 μmol/l) increased the resting tritium outflow in superfused raphe nuclei slices, EC50 5.3 μmol/l. The 2-methyl-5-HT-induced increase of tritium outflow was an external Ca2+-independent process and was not altered by reserpine pretreatment but it was reversed by addition of the 5-HT uptake inhibitor fluoxetine (1 μmol/l). The 5-HT3 receptor antagonists ondansetron and GYKI-46 903 (1 μmol/l) did not antagonize the stimulatory effect of 2-methyl-5-HT on resting tritium outflow. 2-Methyl-5-HT in lower concentration increased the electrically induced tritium overflow from raphe nuclei slices (EC50 0.56 μmol/l) and also from hippocampal slices preloaded with [3H]5-HT. These effects were reversed by 1 μmol/l of ondansetron and GYKI-46903. The 5-HT3 receptor antagonists (1 μmol/l) were without effects on depolarization-evoked [3H]5-HT release at 2 Hz stimulation, when 10 Hz stimulation was used, ondansetron and GYKI-46 903 reduced the tritium overflow from raphe nuclei slices. These data indicate that 5-HT3 receptors positively alter depolarization-induced somatodendritic 5-HT release in the raphe nuclei. They also show that 2-methyl-5-HT is able to evoke 5-HT release not only from vesicles but also from cytoplasmic stores via a transporter-dependent exchange process. 相似文献
7.
Pietro E. di Prampero Urs Boutellier Anouk Marguerat 《Pflügers Archiv : European journal of physiology》1988,412(5):455-461
Mechanical work, ATP, ADP, PC, free creatine and lactate concentrations were determined on IAA poisoned frog sartorii tetanically stimulated in humidified N, at 10°C in isotonic conditions (0.25 or 0.45 P0). Tetanus duration was 0.35 s, number of tetani was varied from 0 (rest) to 25 (exhaustion). The mechanical work performed per mole ATP+PC split (W
P
*
) amounted on the average to 16.7 kJ/mol. It was observed, however, that w
p
*
increased from about 13 to about 24 kJ/mol with decreasing ATP concentration from about 2 (resting value) to about 1 46811q46v653/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">mol/g and that this decrease in ATP was associated with a decrease of the shortening (and relaxation) speed of the muscle to about 30% of the values observed on the first tetanus. It is concluded that the thermodynamic efficiency of muscle contraction, calculated from the ratio of w
P
*
(measured) to the thermodynamic affinity (free energy change) of ATP hydrolysis (estimated) increases from about 0.3 to about 0.5 with decreasing ATP concentration and shortening speed.This work was supported by the Fonds National Suisse de la Recherche Scientifique, Grants 3.332.78 and 3.364.0.82 相似文献
8.
Jens-Jrg Schnorr Lee M. Dunster Ralph Nanan Jürgen Schneider-Schaulies Sibylle Schneider-Schaulies Volker ter Meulen 《European journal of immunology》1995,25(4):976-984
CD46, the major component of the measles virus (MV) receptor complex and a member of the regulators of complement activity (RCA) gene cluster, is down-regulated in MV-infected cells. We investigated whether the reduction of surface CD46 correlates with enhanced sensitivity of lymphoid and monocytic cells to lysis by activated complement. On human U937 cells, acutely or persistently infected with MV-Edmonston (ED) vaccine strain, infection-dependent down-regulation of CD46 confers sensitivity to activated complement, regardless of the pathway of activation and the specificity of the activating antibodies. Interestingly, down-regulation of CD46 alone is sufficient to confer susceptibility of cells to complement lysis despite the continued surface expression of other RCA proteins such as CD35 and CD55. In primary cultures, both peripheral blood lymphocytes and macrophages are efficiently lysed in the presence of complement activated via the alternative pathway after MV infection. In contrast to the MV-ED infection, infection of cells with the lymphotropic MV wild-type strain WTF does not down-regulate CD46. Cells infected with MV-WTF do not exhibit enhanced susceptibility to complement lysis. These data suggest that MV strains similar to WTF that do not down-regulate CD46 may have an enhanced potential for replication and dissemination within the human host, whereas complement-mediated elimination of cells infected with CD46-down-regulating strains of MV, such as ED, may limit the spread of MV infection, and could thus represent an attenuating factor for MV. 相似文献
9.
Varsano Rashkovsky Shapiro Ophir Mark-Bentankur 《Clinical and experimental immunology》1998,113(2):173-182
Human lung cancer expresses cell membrane complement inhibitory proteins (CIP). We investigated whether human lung cancer cell lines also express cell-membrane CIP molecules and whether the biology of CIP molecules in these cell lines differs from that of CIP in normal human respiratory epithelium in culture. The cell lines ChaGo K-1 and NCI-H596 were compared with normal human nasal epithelium in primary cultures in respect to the level of cell membrane CIP expression of membrane cofactor protein (MCP; CD46), decay-accelerating factor (DAF; CD55) and CD59, in respect to the level of cell resistance to complement-mediated lysis, and in respect to the contribution of cell membrane CIP to cell resistance against complement-mediated lysis. We found, using flow cytometry, that both human lung cancer cell lines expressed MCP, DAF and CD59, as did normal nasal epithelial cells. However, normal cells showed a large subpopulation of low DAF-expressing cells (60% of all cells) and a smaller subpopulation of high DAF-expressing cells (40%), while the lung cancer cell lines showed only one cell population, of high DAF expression. In addition, both lung cancer cell lines expressed higher MCP levels, and NCI-H596 cells showed higher levels of CD59. Cell resistance to complement-mediated lysis of both lung cancer cell lines was much higher than that of normal cells. Fifty percent normal human serum, under the same concentrations of complement activators, induced lysis of less than a mean of 10% of lung cancer cells, while lysing up to a mean of 50% of nasal epithelial cells. Lung cancer cell resistance to complement was due to its ability to prevent significant activation of complement upon its cell membrane, as manifested by a failure of complement activators to increase cell membrane deposition of C3-related fragments. The exact mechanism for this resistance remains obscure. Unexpectedly, neutralizing antibodies, anti-MCP and anti-DAF were entirely ineffective and anti-CD59 was only slightly effective (18% mean cell lysis) in increasing the susceptibility of the lung cancer cell lines to complement, while the same antibodies were very effective in facilitating complement-mediated lysis of the normal nasal epithelial cells (50% mean cell lysis with CD59 MoAb). On the other hand, detachment of DAF and CD59 by phosphatidylinositol-specific phospholipase C (PIPLC) from the lung cancer cell lines abrogated their resistance to lysis. We suggest that the biology of cell membrane CIP molecules in human lung cancer cell lines is different from that of CIP in normal respiratory epithelial cells. Human lung cancer cell lines are able to prevent significant complement activation upon its cell membrane and are therefore especially resistant to complement-mediated lysis. Complement resistance may serve this common and highly lethal human cancer as an escape mechanism from the body's immunosurveillance and prevent effective immunotherapy with tumour-specific MoAbs. 相似文献
10.
D. Behne P. Brätter U. Herzfeld D. Kraft 《Journal of molecular medicine (Berlin, Germany)》1978,56(2):69-74
Zusammenfassung Bei 8 gesunden Versuchspersonen (Durchschnittsalter 25,6 Jahre) wurde nach oraler Applikation von 500 mg und 1000 mg Calcium die Calcium-Resorption bestimmt. Hierzu wurde ein Doppelisotopenverfahren mit angereicherten stabilen Calciumisotopen verwendet, das, da im Gegensatz zu Radiotracermethoden jegliche Strahlenbelastung vermieden wird, uneingeschränkt anwendbar ist. Die oral verabreichten Calciumsalze wurden mit48Ca, das intravenös injizierte CaCl2 mit46Ca markiert. Die Bestimmung der beiden Isotope in Serum- und Urinproben erfolgte mit Hilfe der Neutronenaktivierungsanalyse. Für die Resorptionsquote wurde, unabhängig von der Calcium-Dosis, ein Wert von 30% gefunden. Aus dem46Ca-Gehalt im Serum wurde für das in 24 h ausgetauschte Körper-Calcium ein mittlerer Wert von 6,4±1,0 g Calcium oder 98,8±15,4 mg Ca/kg Körpergewicht berechnet. 相似文献