全文获取类型
收费全文 | 102203篇 |
免费 | 11084篇 |
国内免费 | 6517篇 |
专业分类
耳鼻咽喉 | 868篇 |
儿科学 | 1520篇 |
妇产科学 | 775篇 |
基础医学 | 9170篇 |
口腔科学 | 1774篇 |
临床医学 | 13397篇 |
内科学 | 12290篇 |
皮肤病学 | 1135篇 |
神经病学 | 4062篇 |
特种医学 | 3778篇 |
外国民族医学 | 42篇 |
外科学 | 9266篇 |
综合类 | 21989篇 |
现状与发展 | 27篇 |
一般理论 | 14篇 |
预防医学 | 9881篇 |
眼科学 | 2461篇 |
药学 | 11818篇 |
152篇 | |
中国医学 | 8599篇 |
肿瘤学 | 6786篇 |
出版年
2024年 | 543篇 |
2023年 | 1794篇 |
2022年 | 4390篇 |
2021年 | 5547篇 |
2020年 | 4458篇 |
2019年 | 3339篇 |
2018年 | 3286篇 |
2017年 | 3630篇 |
2016年 | 3201篇 |
2015年 | 4819篇 |
2014年 | 6057篇 |
2013年 | 6335篇 |
2012年 | 8833篇 |
2011年 | 9356篇 |
2010年 | 7222篇 |
2009年 | 5891篇 |
2008年 | 6407篇 |
2007年 | 6291篇 |
2006年 | 5736篇 |
2005年 | 4822篇 |
2004年 | 3456篇 |
2003年 | 3400篇 |
2002年 | 2819篇 |
2001年 | 2194篇 |
2000年 | 1529篇 |
1999年 | 1034篇 |
1998年 | 546篇 |
1997年 | 556篇 |
1996年 | 391篇 |
1995年 | 314篇 |
1994年 | 249篇 |
1993年 | 181篇 |
1992年 | 195篇 |
1991年 | 151篇 |
1990年 | 167篇 |
1989年 | 132篇 |
1988年 | 98篇 |
1987年 | 88篇 |
1986年 | 68篇 |
1985年 | 54篇 |
1984年 | 36篇 |
1983年 | 32篇 |
1982年 | 18篇 |
1981年 | 16篇 |
1980年 | 10篇 |
1979年 | 34篇 |
1978年 | 16篇 |
1977年 | 14篇 |
1976年 | 8篇 |
1974年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
51.
目的:探讨保留甲状软骨膜对全喉切除手术进程和病人术后恢复情况的影响。方法:在甲状软骨膜下游离甲状软骨并切断其上角。不结扎和切断舌骨下肌群和喉上动脉。保留之甲状软骨膜用以加强修复咽壁黏膜。结果:本组病例较经典全喉切除术手术时间缩短30min以上。手术中出血在100ml以下。患者术后第2d下床活动,第4d开始进食流质。手术创口均一期愈合。结论:全喉切除术中保留甲状软骨膜可有效地简化手术步骤,减少创伤和出血。利用甲状软骨膜加强咽壁黏膜缝合口,进一步减少了咽漏的发生. 相似文献
52.
Genetic imbalances in pleomorphic xanthoastrocytoma detected by comparative genomic hybridization and literature review. 总被引:2,自引:0,他引:2
Xiao-Lu Yin Angela Bik-Yu Hui Eleanore C Liong Min Ding Alex R Chang Ho-Keung Ng 《Cancer Genetics and Cytogenetics》2002,132(1):14-19
Pleomorphic xanthoastrocytoma (PXA) is a rare, low-grade astrocytic tumor found in the central nervous system. Histologically, the tumor is characterized by markedly pleomorphic and lipidized cells. Although most of the patients have a favorable prognosis, a small number of cases undergoing recurrence or progression to anaplastic astrocytoma were reported. Very few genetic studies have been performed on PXA because of its rarity and the pathogenesis of this neoplasm is largely unknown. In order to provide an overview of genetic alterations in PXA, we performed comparative genomic hybridization to identify chromosomal imbalances (DNA gains and losses) in three cases of PXA. Genetic imbalance was detected on at least one chromosome for each case. One case, which revealed multiple genetic alterations, showed a poor prognosis. DNA gain on chromosome 7 and loss on 8p were demonstrated in two of three cases, suggesting that the candidate gene(s) located on these regions may play a role in the development of PXA. Further studies are needed to identify the residing candidate genes that are involved in the tumorigenesis of PXA. In addition, the histopathological features and previous genetic studies on PXA are reviewed. 相似文献
53.
Adam J. Kaplan Kenneth D. Chavin Li Hui Qin Hideo Yagita Jonathan S. Bromberg 《Immunologic research》1994,13(1):42-48
The baculovirus expression system was used to produce three different constructs of the murine cell surface adhesion receptor CD2. One construct coded for a single, N-terminal, Ig-fold domain. It was inefficiently secreted and therefore primarily intracellular. The second construct coded for both extracellular, N-terminal Ig-fold domains. This was efficiently secreted into culture supernatant. The third construct coded for the full-length transmembrane molecule which localized to the cell surface. All constructs were monomers of predicted MWr and were appropriately glycosylated. They retained epitopic specificity as demonstrated by binding to mAbs, and adhesion function as demonstrated by a rosetting assay. 相似文献
54.
LJM, a 41-year-old schizophrenic Chinese man with bilateral anterior cingulate gyrus (Brodmann's area 24) lesions and also a small lesion in right amygdala after an operation, was compared with normal as well as brain-damaged and schizophrenic controls in identification of morphed facial expressions of six basic emotions. In repeated administrations of the test for recognition of facial emotions, over a 1- year period, LJM performed significantly worse for expressions of fear compared with the three groups of controls. Recognition of other emotions was not significantly different from that of the controls, except that his recognition of disgust during the first session (but not in two subsequent sessions) was worse than normal and brain-damaged controls but not worse than schizophrenic controls. The dissociation between recognition of fear and other emotions supported the view that the brain has separable networks for processing different emotions, and that the right amygdala as well as the anterior part of bilateral cingulate gyrus are possible substrates involved in the special network for perception of fear. The results from the various groups of Chinese subjects indicate that they perceive emotions in a categorical manner, and that the six basic emotions are likely to be cross-cultural universals. 相似文献
55.
乙醇对人绒毛孕酮分泌的影响 总被引:1,自引:0,他引:1
本工作利用灌流技术观察了四种不同浓度的乙醇(0.5%、1%、2.5%、5%)对妊娠早期人工流产新鲜胎盘绒毛分泌孕酮的影响。结果表明,乙醇具有促进孕酮分泌的作用,并存在剂量依赖的关系。提示乙醇可能破坏胎盘激素内分泌的平衡,从而影响胎儿的正常生长与发育。 相似文献
56.
本实验选用具有生育力成年雄性猕猴7只,在直视下行双侧HFMC输精管内注射,每侧剂量分别为30mg1只,60mg和100mg各3只;于注射后2.5年和3.5年分别处死动物,取睾丸组织进行光镜和电镜观察.结果发现:猕猴注射HFMC2.5年后,睾丸光镜大部分曲细精管生精上皮结构完整,排列整齐。仅见局部少数管腔生精上皮层数减少,上皮细胞轻度水样变性等病理改变。电镜下曲细精管内除支持细胞内脂褐素增多,轻度基底膜增厚和精母细胞内质网扩张外,各级生精细胞,支持细胞及细胞间连接复合体等超微结构未见明显异常。注射HFMC3.5年后猕猴的光镜、电镜结果与注射后2.5年结果相似,但局部改变较2.5年组轻。上述结果表明:猕猴输精管内注射一定剂量HFMC节育不会引起睾丸组织的严重病理改变。但是,由于注射HFMC后,HFMC释放H+及其对输精管的暂时阻塞,改变了精子生存的内环境,使睾丸出现局部轻度病理改变,随着HFMC逐渐溶解排出,睾丸功能相继恢复正常,配对产仔。为HFMC应用提供了安全性依据。 相似文献
57.
Yvonne Myal Carolyn Gregory Hui Wang John L. Hamerton Robert P. C. Shiu 《Somatic Cell and Molecular Genetics》1989,15(3):265-270
The hormonally responsive prolactin-inducible protein (PIP), gene is expressed in benign and malignant breast tumor tissues and in such normal exocrine organs as sweat, salivary, and lacrimal glands. In this communication we report the regional chromosome localization of the PIPgene locus to chromosome 7 by Southern hybridization to DNA from human-hamster somatic cell hybrids, and to 7q32–36 by in situ hybridization. 相似文献
58.
Induction of protective immunity to monoclonal-antibody-defined Plasmodium falciparum antigens requires strong adjuvant in Aotus monkeys. 总被引:3,自引:4,他引:3
W A Siddiqui L Q Tam S C Kan K J Kramer S E Case K L Palmer K M Yamaga G S Hui 《Infection and immunity》1986,52(1):314-318
Monoclonal antibodies to the major Plasmodium falciparum merozoite surface coat and rhoptry antigens were produced. A combination of the affinity-purified polypeptides with Freund complete adjuvant which was given three times completely protected an Aotus lemurinus azure (karotype VI) monkey against homologous challenge; however, immunization with the same polypeptides with a muramyl dipeptide derivative [MDP-Lys(L18)] did not protect a second Aotus monkey, even though comparable high antibody titers were induced. 相似文献
59.
PENA方法的建立及与ELISA IgM检测CMV的比较 总被引:1,自引:0,他引:1
目的 介绍一种敏感、稳定、快速、简便的实验室检测CMV的方法 ,同时探讨该种新方法与ELISA检测CMV方法的优、缺点。方法 对 5 5 2例病人应用间接荧光免疫法测定细胞核中的特异病毒早期抗体 (PENA)和ELISA法测定IgM抗体。结果 PENA方法 :强阳性 88例 ,阳性率 15 4 9% ,弱阳性 2 73例 ,阳性率 5 9 4 6 % ;ELISA -IgM方法 :阳性 34例 ,阳性率6 16 %。结论 PENA方法操作简便 ,与ELISA方法相比较 ,可对CMV感染进行早期测定及诊断 ,并可区分既往感染和即时感染 ,具有敏感性和稳定性 ,是测定小儿CMV感染的一种较好的方法 相似文献
60.
目的测量2450MHz频率下蒸馏水和不同浓度NaCl溶液的复介电常数,用以判定系统的可靠性和稳定性.方法根据微扰法得到复介电常数的测量公式,然后通过实验对已知参数的蒸馏水和NaCl溶液进行测量,并计算其复介电常数和电导率,验证计算结果的可靠性和稳定性.结果对计算结果进行统计分析和误差分析,其均值、标准差和变异系数表明,最终结果可与M.I.T标准较好地吻合.结论这种系统可较好地测量2450MHz频率下高损耗介质的复介电常数,测量系统的主要误差是由介质体积的误差引起的,因此精确测量介质体积是测量生物组织等高损耗介质复介电常数的关键. 相似文献