全文获取类型
收费全文 | 38544篇 |
免费 | 3723篇 |
国内免费 | 2487篇 |
专业分类
耳鼻咽喉 | 301篇 |
儿科学 | 580篇 |
妇产科学 | 460篇 |
基础医学 | 3409篇 |
口腔科学 | 663篇 |
临床医学 | 5188篇 |
内科学 | 4961篇 |
皮肤病学 | 518篇 |
神经病学 | 1550篇 |
特种医学 | 1231篇 |
外国民族医学 | 10篇 |
外科学 | 3242篇 |
综合类 | 8073篇 |
现状与发展 | 23篇 |
一般理论 | 1篇 |
预防医学 | 3402篇 |
眼科学 | 727篇 |
药学 | 4918篇 |
48篇 | |
中国医学 | 2846篇 |
肿瘤学 | 2603篇 |
出版年
2024年 | 146篇 |
2023年 | 520篇 |
2022年 | 1305篇 |
2021年 | 1660篇 |
2020年 | 1322篇 |
2019年 | 1089篇 |
2018年 | 1103篇 |
2017年 | 1232篇 |
2016年 | 1065篇 |
2015年 | 1723篇 |
2014年 | 2125篇 |
2013年 | 2320篇 |
2012年 | 3384篇 |
2011年 | 3412篇 |
2010年 | 2506篇 |
2009年 | 2078篇 |
2008年 | 2450篇 |
2007年 | 2507篇 |
2006年 | 2339篇 |
2005年 | 2071篇 |
2004年 | 1449篇 |
2003年 | 1447篇 |
2002年 | 1105篇 |
2001年 | 830篇 |
2000年 | 729篇 |
1999年 | 561篇 |
1998年 | 341篇 |
1997年 | 315篇 |
1996年 | 227篇 |
1995年 | 215篇 |
1994年 | 179篇 |
1993年 | 98篇 |
1992年 | 141篇 |
1991年 | 97篇 |
1990年 | 111篇 |
1989年 | 64篇 |
1988年 | 83篇 |
1987年 | 72篇 |
1986年 | 69篇 |
1985年 | 49篇 |
1984年 | 24篇 |
1983年 | 22篇 |
1982年 | 14篇 |
1981年 | 23篇 |
1980年 | 14篇 |
1979年 | 24篇 |
1976年 | 15篇 |
1973年 | 9篇 |
1969年 | 7篇 |
1965年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
41.
肥厚性瘢痕组织中VEGF、ICAM-1、c-fos表达的变化 总被引:4,自引:2,他引:2
目的 检测与血管内皮细胞激活及增生相关的血管内皮生长因子(VEGF)、细胞间粘附分子-1(ICAM-1),以及c-fos原癌基因在肥厚性瘢痕组织中的表达。方法 采用免疫组化SP方法,比较VEGF、ICAM-1、c-fos在肥厚性瘢痕、正常瘢痕、正常皮肤组织中的表达。结果 VEGF、ICAM-1、c-fos在肥厚性瘢痕中表达皆增强。VEGF、c-fos主要表达在表皮、真皮血管、皮肤附属器;ICAM-1主要表达在真皮浅层血管、浸润的炎细胞、成纤维细胞。结论 肥厚性瘢痕组织中血管内皮细胞处于一种激活状态,肥厚性瘢痕组织内皮细胞和成纤维增殖异常。 相似文献
42.
应用肝素雾化治疗小儿哮喘性疾病(包括以喘为主的支气管肺炎)16例,其咳喘症状消失和肺部体征消失时间校对照组快,总显效率高。文中还就7例肝素雾化治疗前后血气结果对照,进一步阐述肝素雾化有利于改善通气功能,促进二氧化碳排出和炎症吸收,从而解除支气管痉挛的机理。具有疗效显著,安全可靠,无任何副作用的特点,值得临床推广应用。 相似文献
43.
TSG-6基因在3T3-L1脂肪细胞诱导分化中表达水平的变化 总被引:2,自引:0,他引:2
[目的] 探讨TSG-6基因在3T3-L1脂肪细胞诱导分化中表达水平的变化。[方法] 采用细胞培养和RT-PCR技术,检测细胞诱导分化不同时段脂肪细胞中TSG-6基因的表达水平。[结果] ①随着脂肪细胞逐渐分化成熟,TSG-6基因mRNA表达水平逐渐升高;②TSG-6基因表达水平除在细胞分化第0-2d、第3-5d和第7-10d各时段内差异无显著性(P>0.05)外,其余各时段之间表达水平差异均有显著性(P<0.05)。[结论] TSG-6基因与细胞分化以及脂原形成可能相关。 相似文献
44.
Monoclonal antibody PAb3 to c-erbB-2/neu protein was utilized in the immunoperoxidase staining of 86 human specimens from oral mucosa. These tissue specimens represented a spectrum from 7 normal to 9 simple hyperplasia, 15 mild dysplasia, 14 moderate dysplasia, 20 severe dysplasia and 21 squamous cell carcinoma. Our study indicated that as the cells acquire a more malignant phenotype, there was a progressive increase in neu expression. It also suggested that neu may be involved in the development of oral cancers and that its evaluation in the early stages may assist in the diagnosis and management of oral cancers. 相似文献
45.
女性飞行学员高空飞行生理生化耐受能力研究 总被引:1,自引:0,他引:1
为从高空缺氧耐力训练前后生理、生化角度探讨中国女飞行员驾驶战斗机的可行性,在地面模拟高空缺氧及高空飞行训练前后行心电图、心率、血氧饱和度、血压、血尿酸(BUA)、肌酸激酶(CK)、血红蛋白(Hb)、乳酸(BLA)、肌酐(Cr)和天冬氨酸转氨酶(AST)测定,并与男飞行学员的测定结果比较.发现男女飞行学员的心电图、心率、血氧饱和度、血压、Cr、CK、BUA和AST均无显著性差异;女飞行学员在高空耐缺氧Hb代偿反应高于男飞行学员(P<0.05),而BLA水平低于男飞行学员(P<0.05).认为中国女飞行学员在生理生化耐受能力上能胜任飞战斗机. 相似文献
46.
Increased expression of certain glutathione S-transferase (GST) isoenzymes has frequently been associated with the development of resistance to alkylating agents and other classes of antineoplastic drugs in drug-selected cell lines. The question arises whether this phenomenon is causal or is a stress-induced response associated with drug resistance in these cell lines. We have constructed mammalian expression vectors containing the human GST mu and GST alpha 2 (Ha2) cDNAs and stably transfected them into the human breast cancer cell line MCF-7. Whereas the parental and pSV2neo-transfected cell lines display low GST activity, three individual transfected clones were identified in each group that expressed either GST mu or GST alpha 2. The range of GST activities was similar to those observed in cells selected for anticancer drug resistance. The GST mu specific activities were 56, 150, and 340 mlU/mg, compared with 10 mlU/mg of endogenous GST mu in control lines. Specific activities in GST alpha 2-transfected clones were 17, 28, and 52 mlU/mg, compared with no detectable alpha class GST in control lines. These clonal lines and the parental and pSV2neo-transfected control lines were tested for sensitivity to antineoplastic agents and other cytotoxic compounds. The clones with the highest activity in each group were 1.7-fold (GST alpha 2) to 2.1-fold (GST mu) resistant to the toxic effects of ethacrynic acid, a known substrate for GSTs. However, the GST-transfected cell lines were not resistant to doxorubicin, L-phenylalanine mustard, bis(2-chloroethyl)-1-nitrosourea, cisplatin, chlorambucil, or the GST substrates 1-chloro-2,4-dinitrobenzene or tert-butyl hydroperoxide. Thus, although L-phenylalanine mustard, bis(2-chloroethyl)-1-nitrosourea, chlorambucil, tert-butyl hydroperoxide, and 1-chloro-2,4-dinitrobenzene are known to be metabolized by glutathione-dependent GST-catalyzed reactions, there was no protection against any of these agents in MCF-7 cell lines overexpressing GST mu or GST alpha 2. We conclude that, at the levels of GST obtained in this transfection model system, overexpression of GST mu or GST alpha 2 is not by itself sufficient to confer resistance to these anticancer agents. These studies do not exclude the possibility that GST may be a marker of drug resistance or that other gene products not expressed in MCF-7 cells might cooperate with GST to confer drug resistance. 相似文献
47.
Age and gender related changes in stereoselective pharmacokinetics and pharmacodynamics of verapamil and norverapamil. 总被引:2,自引:2,他引:0 下载免费PDF全文
S K Gupta L Atkinson T Tu J A Longstreth 《British journal of clinical pharmacology》1995,40(4):325-331
1. Pharmacokinetics and pharmacodynamics of R- and S-verapamil and R- and S-norverapamil were studied at steady state following administration of 180 mg verapamil delivered by a controlled-release gastrointestinal therapeutic system (COER-verapamil). 2. Of the 30 young (19 to 43 years) and 30 elderly subjects (65 to 80 years) enrolled, approximately half of each age group were women; all subjects were healthy and none were smokers. 3. Mean R- and S-verapamil and R- and S-norverapamil Cmax, Cmin, and AUC values for elderly subjects were 1.2 to 2.2 times greater than those for young subjects; these differences were statistically significant at P < 0.05. Median tmax values for young and elderly subjects were not significantly different for any enantiomer. The mean half-life values of R- and S-verapamil for elderly subjects were approximately 20 h compared with approximately 13 h for young subjects, respectively. The mean half-life values of R- and S-norverapamil for elderly subjects were approximately 31 h and 20 h, respectively, compared with approximately 19 h and 21 h for young subjects, respectively. 4. In both age groups, the mean plasma verapamil concentrations of each enantiomer were higher for women than for men at all time points. 5. Mean arterial pressure (MAP) had a significant correlation to R- (r2 = 0.86) and S-verapamil (r2 = 0.87) concentration values that was not influenced by either gender or age of the patient. Change in PR-interval also had a significant correlation to R- and S-verapamil concentration values. However, the sensitivity of the response to changes in R- and S-verapamil concentration values in elderly subjects was about 1/5 of that in younger subjects. 相似文献
48.
超细纤维乳管镜引导下乳管内肿瘤切除术 总被引:8,自引:5,他引:3
目的探讨超细纤维乳管镜引导下乳管内肿瘤切除术的应用价值。方法对312例乳头溢液进行乳管镜检查,其中乳管内发现肿瘤者行手术治疗。利用乳管镜冷光源的皮肤透照点定象限,乳管扩张器探针定乳管走行方向,亚甲蓝染色定乳管末梢的分布。结果78例导管内发现肿瘤:单发性乳头状瘤68例,乳头状瘤病5例,导管内癌5例。28.2%(22/78)的病灶位于总导管,48.7%(38/78)位于导管Ⅰ级分支,17.9%(14/78)位于Ⅱ级分支,位于Ⅲ级和Ⅳ级分支病灶仅占3.8%(3/78)和1.3%(1/78)。病灶距乳头开口的平均距离为2.5cm(1~5cm)。78例均行手术治疗。术后病理诊断证实:65例乳头状瘤,8例乳头状瘤病,5例为导管内癌。乳管镜诊断符合率:乳头状瘤96%(65/68),乳头状瘤病100%(5/5),导管内癌100%(5/5)。单纯导管切除术65例,区段切除术8例,保乳根治术3例,改良根治术2例。结论通过光、针、色三位一体的方法定位以最小的切除范围达到最准确的切除目的,实现乳管内肿瘤的微创治疗。 相似文献
49.
目的:探讨活动性系统性红斑狼疮(SLE)患者血清中4种胶原成分的变化及临床意义。方法:采用放射免疫分析法对41例活动期SLE患者及其中伴有沸间质改变、肾脏改变、雷诺征或三者共存者血清Ⅲ型前胶原(PC—Ⅲ)、Ⅳ型肢原(Ⅳ—C)、透明质酸(HA)、层粘连蛋白(LN)进行到定。结果:4种胶原成分均明显高于对照组(P<0.01或P<0.05)。结论:4种胶原成分的变化在SLE的诊断、治疗、病情判定、评估预后中,特别是肝、肾、肺病变的监测中具有重要作用。 相似文献
50.