全文获取类型
收费全文 | 59905篇 |
免费 | 5559篇 |
国内免费 | 4271篇 |
专业分类
耳鼻咽喉 | 614篇 |
儿科学 | 560篇 |
妇产科学 | 576篇 |
基础医学 | 6883篇 |
口腔科学 | 1202篇 |
临床医学 | 7847篇 |
内科学 | 8594篇 |
皮肤病学 | 677篇 |
神经病学 | 2636篇 |
特种医学 | 1926篇 |
外国民族医学 | 41篇 |
外科学 | 6023篇 |
综合类 | 10729篇 |
现状与发展 | 19篇 |
一般理论 | 14篇 |
预防医学 | 4558篇 |
眼科学 | 1672篇 |
药学 | 6398篇 |
66篇 | |
中国医学 | 3484篇 |
肿瘤学 | 5216篇 |
出版年
2024年 | 238篇 |
2023年 | 936篇 |
2022年 | 2368篇 |
2021年 | 3184篇 |
2020年 | 2353篇 |
2019年 | 1934篇 |
2018年 | 2075篇 |
2017年 | 1835篇 |
2016年 | 1697篇 |
2015年 | 2840篇 |
2014年 | 3406篇 |
2013年 | 2966篇 |
2012年 | 4282篇 |
2011年 | 4750篇 |
2010年 | 3296篇 |
2009年 | 2669篇 |
2008年 | 3184篇 |
2007年 | 3189篇 |
2006年 | 3168篇 |
2005年 | 3055篇 |
2004年 | 2254篇 |
2003年 | 2096篇 |
2002年 | 1708篇 |
2001年 | 1455篇 |
2000年 | 1347篇 |
1999年 | 1367篇 |
1998年 | 920篇 |
1997年 | 870篇 |
1996年 | 641篇 |
1995年 | 671篇 |
1994年 | 560篇 |
1993年 | 330篇 |
1992年 | 370篇 |
1991年 | 335篇 |
1990年 | 293篇 |
1989年 | 250篇 |
1988年 | 204篇 |
1987年 | 199篇 |
1986年 | 133篇 |
1985年 | 114篇 |
1984年 | 65篇 |
1983年 | 39篇 |
1982年 | 26篇 |
1981年 | 27篇 |
1980年 | 8篇 |
1979年 | 22篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
用PCR技术对12例神经肌肉性疾病患者的16个标本进行了线粒体DNA缺失情况的研究。发现2例帕金森氏病患者的肌肉组织以及其中1例的外周血和另1例肌营养不良(Erb型)患者的肌肉组织中线粒体DNA至少有526bp的缺失。还对线粒体DNA的部分缺失与疾病发生的关系进行了讨论。 相似文献
63.
理气类中药对大鼠离体胃平滑肌条的作用 总被引:9,自引:0,他引:9
目的:观察理气类中药对大鼠离体胃平滑肌条运动的影响。方法:将肌条放置在灌流肌槽中,用生理记录仪记录肌条的收缩活动。结果:陈皮、枳实对胃各部位平滑肌条均为抑制效应,香附、薤白、木香、柿蒂、乌药对胃底肌条为兴奋效应,但对其他部位肌条则表现为兴奋或抑制不同的效应,沉香仅降低胃窦环行肌收缩波平均振幅,对其他肌条无影响。结论:理气类中药对大鼠离体胃平滑肌条既有兴奋作用,也有抑制作用。 相似文献
64.
本文通过犬急性心肌缺血-再灌注模型探讨缺血-再灌注心肌Ca2+超负荷的发生机制。当心肌持续缺血150min,心肌细胞内Ca2+、Na+增加、K+降低;心肌细胞膜Na+-K+-ATPase、Ca2+-ATPase活性降低,心肌组织丙二醛(MDA)含量增加.而心肌缺血90min后,再灌注60min,与之比较细胞内Ca2+明显增加,伴Na+升高、K+降低,心肌细胞膜Na+-K+-ATPase、Ca2+-ATPase活性降低,MDA含量增加,说明缺血-再灌注过程中Na+升高、Na+-Ca2+交换增加,Ca2+-ATPase活性降低是细胞内Ca2+超负荷发生的重要原因。 相似文献
65.
本文应用“冷沉淀”法制备纤维组织粘合剂。对纤维组织粘合剂中主要成份和含量进行了测定,并测定了主要理化性质,建立了动物实验模型,观察了实验兔对纤维粘合剂的反应。 相似文献
66.
L Fuller J Fernandez S Zheng M Carreno V Esquenazi W C Yang J Miller 《Transplantation》1992,53(1):195-202
We have advanced the hypothesis that the primary autolymphoproliferative response of dog T cells in mixed lymphocyte kidney cultures (MLKC) results from their recognition of tissue-specific (kidney-associated) antigen(s) presented in conjunction with class II MHC antigens. Lymphocyte culture-derived supernatants had been found previously to upregulate class II antigen expression on kidney cells and enhance T cell activation. In the present study we have isolated and characterized dog IFN-gamma, a class II-inducing substance that is secreted in the culture supernatant of activated T lymphocytes. Dog IFN-gamma was induced with A-23187 and PMA and purified stepwise using controlled-pore glass, Mono Q anion exchange chromatography, and Superose 6-gel filtration on FPLC. The purification resulted in two molecules of 42 Kd and 31 Kd molecular weights. An IgG1 monoclonal antibody was engendered to these molecules. With this mAb reagent, in immunochemical experiments, we have developed a sensitive ELISA and a method for purifying dog IFN-gamma by affinity chromatography. Species specificity studies indicated that purified dog IFN-gamma reacted with a polyclonal rabbit antihuman IFN-gamma, but not with a mAb to human IFN-gamma. However, the antidog IFN-gamma mAb that was generated also reacted with recombinant human IFN-gamma. In in vitro biological studies, the purified IFN-gamma (two mol. wt. species) upregulated the expression of canine class II MHC molecules on dog tubular epithelial cells and the dog kidney epithelial cell line (MDCK). The antidog IFN-gamma mAb blocked T cell proliferative response to kidney cell and, by inference, the interaction between endogenously released IFN-gamma in vitro with its cell surface receptor, thus inhibiting the induced upregulation of class II. Interestingly, although antidog IFN-gamma markedly blocked the MLKC (10 micrograms mAb/well), there was no effect on the allogeneic MLC. This observation indicates that the cytokine IFN-gamma may be a uniquely key substance amplifying the immune response of T cells to tissue-associated antigens on surrogate antigen-presenting cells that require induced upregulation of class II MHC antigen expression (MLKC), in contrast to reactions in which these antigens are already constitutively expressed on the antigen-presenting cells (mixed lymphocyte culture). 相似文献
67.
目的:了解近年来泌尿系细菌感染致病菌及耐药性,为合理应用抗生素,提供临床根据。方法:对泌尿系感染患者298株病原菌进行药物敏感试验。结果:大肠埃希菌仍是引发泌尿系感染的主要病原菌,占53%,其次是葡萄球菌属,占19.40%,肠杆菌属占10.06%,肠球菌属占4.70%等,各类菌属耐药情况。结论:临床医师必须关注本地病原菌分布及耐药情况,合理应用抗生素,减少耐药性播散。 相似文献
68.
Ronald G. Pratt Jie Zheng Brent K. Stewart Yoseph Shiferaw Anthony J. McGoron Ranasinghage C. Samaratunga Stephen R. Thomas 《Magnetic resonance in medicine》1997,37(2):307-313
A limited flip angle gradient-echo 3D volume acquisition imaging protocol for mapping partial pressure of oxygen (pO2) in perfluorocarbon compounds (PFCs) at low field (0.14 T) is presented. The pO2 measurement method is based on the paramagnetic effect of dissolved molecular oxygen (O2) which reduces the PFC 19F T1? Specific objectives related to imaging of PFCs through use of the protocol include improved image signal-to-noise characteristics and elimination of 19F chemical shift artifacts. A parametric Wiener deconvolution filtering algorithm is used for suppression of 19F chemical shift artifacts. Application of the protocol is illustrated in a series of calculated pO2 maps of a gas equilibrated, multi-chamber phantom containing perfluorotributylamine (FC-43). The utility of the protocol is demonstrated in vivo through images of a commercially available perfluorocarbon based blood substitute emulsion containing FC-43 sequestered in the liver and spleen of a rat. 相似文献
69.
Assessment of carbohydrate tolerance in pregnancy 总被引:4,自引:0,他引:4
E A Reece E Assimakopoulos Z Hagay N DeGennaro X Z Zheng J C Hobbins 《Obstetrical & gynecological survey》1991,46(1):1-14
A review is given of the various methods of assessing carbohydrate tolerance in pregnancy. Oral glucose tolerance screening and diagnostic tests have been in use for more than 25 years. They are easily administered, relatively inexpensive, and present reasonable sensitivity; therefore, they continue to be used quite extensively. However, lack of reproducibility of the results and side effects such as nausea, vomiting, and headache have led to the use of alternate methods including glucose polymer (Polycose) and standard breakfast meals. These methods have been reported to present satisfactory results in clinical practice. Glycosylated hemoglobin (HbA1c) and fructosamine assays are also alternate forms of testing carbohydrate metabolism HbA1c measurement have been proven insensitive as a screening test for gestational diabetes, while their use as an index of overall glucose control remains valuable. The role of fructosamine in the assessment of carbohydrate intolerance remains controversial with conflicting claims made by various investigators regarding its sensitivity in detecting gestational diabetes and its response to alterations in glycemic control. In this review, the relative advantages and disadvantages of each glucose tolerance test are discussed and recommendations are given regarding their utility in pregnancy. 相似文献
70.
目的了解流行性出血热病毒(EHFV)对心脏的损害情况。方法对103例流行性出血热(EHF)患者的心电图及心肌酶学检测结果进行分析。结果72例(69.9%)患者出现心电图异常,以窦性心动过缓(27.9%)及窦性心动过速(22.3%)最常见,明显高于其它类型的心电图改变(P分别<0.05和0.001)。103例流行性出血热(EHF)患者的CK、LDH及HBDH的升高者分别为43例(41.2%)、73例(70.9%)及46例(44.7%),以LDH异常最常见。轻型、中型、重型及危重型流行性出血热患者的LDH值分别为(346.3±155.6)IU/L、(330.7±130.7)IU/L、(1114.4±872.4)IU/L及(1227.1±936.7)IU/L,经统计学处理重型及危重型的值与轻型、中型比较均有显著性或高度显者性差异。结论EHF患者并发心肌损害较普遍,而且病情愈重者,心肌损害愈严重。 相似文献