全文获取类型
收费全文 | 25087篇 |
免费 | 2245篇 |
国内免费 | 2117篇 |
专业分类
耳鼻咽喉 | 170篇 |
儿科学 | 249篇 |
妇产科学 | 231篇 |
基础医学 | 2952篇 |
口腔科学 | 389篇 |
临床医学 | 3357篇 |
内科学 | 3593篇 |
皮肤病学 | 165篇 |
神经病学 | 1279篇 |
特种医学 | 861篇 |
外国民族医学 | 18篇 |
外科学 | 2903篇 |
综合类 | 4338篇 |
现状与发展 | 4篇 |
一般理论 | 1篇 |
预防医学 | 1756篇 |
眼科学 | 658篇 |
药学 | 2733篇 |
24篇 | |
中国医学 | 1382篇 |
肿瘤学 | 2386篇 |
出版年
2024年 | 109篇 |
2023年 | 408篇 |
2022年 | 1040篇 |
2021年 | 1217篇 |
2020年 | 956篇 |
2019年 | 836篇 |
2018年 | 859篇 |
2017年 | 745篇 |
2016年 | 778篇 |
2015年 | 1133篇 |
2014年 | 1389篇 |
2013年 | 1213篇 |
2012年 | 1699篇 |
2011年 | 1956篇 |
2010年 | 1250篇 |
2009年 | 995篇 |
2008年 | 1310篇 |
2007年 | 1360篇 |
2006年 | 1283篇 |
2005年 | 1326篇 |
2004年 | 816篇 |
2003年 | 915篇 |
2002年 | 689篇 |
2001年 | 575篇 |
2000年 | 636篇 |
1999年 | 748篇 |
1998年 | 461篇 |
1997年 | 462篇 |
1996年 | 324篇 |
1995年 | 304篇 |
1994年 | 307篇 |
1993年 | 171篇 |
1992年 | 216篇 |
1991年 | 179篇 |
1990年 | 151篇 |
1989年 | 151篇 |
1988年 | 126篇 |
1987年 | 103篇 |
1986年 | 75篇 |
1985年 | 82篇 |
1984年 | 28篇 |
1983年 | 17篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 19篇 |
1974年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
纪震 《中国医疗器械杂志》1999,23(5):252-257
提出基于自适应方向滤波方法来提取左心室轮廓。在噪声的干扰下,引入经平滑处理的方向滤波能够得到精确的边缘,所获得的边缘方向矢量能够在边缘跟踪时对边缘走向预测,同时对参数进行自适应地调整。通过尽量少的人机交互,算法能够自动提取出左心室的轮廓。实验证明该算法增加了边缘提取的精度和一致性,同时显著地降低了计算复杂度。 相似文献
62.
半导体红外激光光凝治疗视网膜静脉阻塞 总被引:7,自引:0,他引:7
为探讨半导体红外激光对视网膜静脉阻塞(RVO)的治疗效果,对58例RVO患者用Keeler公司“Microlase”半导体激光器(波长810nm)作区域封闭或全视网膜光凝(PRP)。结果:17例中央视网膜静脉阻塞(CRVO)患者,治疗前后平均视力分别为0.175及0.40;7例半球阻塞(Semi-CRVO)患者治疗前后平均视力为0.116及0.40;34例视网膜分枝静脉阻塞(BRVO)患者则分别为0.19及0.465。经t检验,差别均有显著性。结论:激光光凝治疗是RVO重建供氧平衡的重要手段,疗效肯定。半导体红外激光有比氩激光更易穿透浑浊介质和更少影响视网膜神经纤维层和黄斑功能等优点。早期进行区域封闭或全视网膜光凝,有利于保存有用视力。 相似文献
63.
BACKGROUND: The field of psychiatric epidemiology continues to employ self-report instruments, but the low degree of agreement between diagnoses achieved using these instruments vs. that achieved by psychiatrists in the clinical modality threatens the credibility of the results. METHODS: In the Baltimore Epidemiologic Catchment Area follow-up, 349 individuals who had a Diagnostic Interview Schedule (DIS) interview were blindly examined by psychiatrists using the Schedules for Clinical Assessment in Neuropsychiatry (SCAN). Comparisons were made at the level of diagnosis, syndrome, and DSM-IV symptom group. Indexes of agreement were computed and characteristics of discrepant cases were identified. RESULTS: Agreement on diagnosis of major depressive disorder was only fair (kappa = 0.20), with the DIS missing many cases judged to meet criteria for diagnosis using the SCAN (29% sensitivity). A major source of discrepancy was respondents with false-negative diagnoses who repeatedly failed to report DIS symptoms attributed to life crises or medical conditions. Older age, male sex, and lower impairment were associated with underdetection by the DIS, using logistic regression analysis. In spite of the diagnostic discrepancy, there was substantial correlation in numbers of symptom groups in the 2 modalities (r = 0.49). Agreement was highest (about 55% sensitivity and 90% specificity) when both the SCAN and DIS thresholds were set at the level of depression syndrome instead of diagnosis. CONCLUSIONS: Weak agreement at the level of diagnosis continues to threaten the credibility of estimates of prevalence of specific disorders. A bias toward underreporting, as well as stronger agreement at the level of the depression syndrome and on ordinal measures of depressive symptoms, suggests that associations with risk factors are conservative. 相似文献
64.
目的 研究可溶性血管细胞黏附分子 1(solublevascularcelladhesionmolecule - 1,sVCAM - 1)在妊高征发病中的作用。方法 用酶联免疫吸附法 (ELISA)测定 6 7例孕妇血清中sVCAM - 1水平 ,其中正常妊娠组 15例 ,妊高征组 5 2例。结果 中、重度妊高征患者血中sV CAM - 1水平显著高于正常妊娠组 (P <0 .0 1) ;轻度妊高征患者与正常妊娠组相比 ,虽无统计学差异 ,但有升高趋势 ;妊高征组产后该指标下降 ,与正常妊娠组比较无显著性差异 (P >0 0 5 )。sVCAM - 1浓度与平均动脉压呈正相关 (r =0 .5 4 2 ,P <0 .0 1)。结论 妊高征患者血中sVCAM - 1水平升高 ,表明内皮细胞损伤在妊高征的发病中起重要作用。 相似文献
65.
66.
非体外循环下小儿腔肺吻合术疗效分析 总被引:4,自引:0,他引:4
为总结体外循环与非体外循环的两组病例行双向腔肺吻合(M.Glenn)术后的转归,以客观评价小儿施行非体外循环腔肺吻合术的可行性,将2000年5月--2002年11月行单纯M.Glenn术的32例患儿(年龄0.33--ll岁,体重6—32kg)分为两组,A组(n=16)为体外循环组,B组(n=16)为非体外循环组。所有病例监测术后1、6、12、24、48h氧合指数(OI);测定人ICU即刻(T1)、呼吸机撤离前、后(T2和T3)3个时间点的中心静脉压(CVP)、跨肺压(TPG)、跨脑压(TCP);记录两组病例手术时间(OT)、术后并发症、术后12h用血球量、呼吸机使用时间(VT)、ICU滞留时间(IT)以及住院费用。结果显示,B组术后OI均高于A组,尤其在术后lh和6h,OI分别为A组的1.4倍和1.3倍,差异有非常显著性(P<0.01)。尽管撤机前B组CVP为A组的1.3倍(P<0.05),TCP明显低于A组,但撤机后两组差异无显著性。两组VT、IT差异虽无显著性(P>0.05),但B组术后12h用血球量、并发症明显降低,住院开支亦较A组节省了约30%(P<0.05)。提示非体外循环技术应用于小儿双向腔肺吻合术是可行且有利的。 相似文献
67.
HSP27在大肠癌及癌旁组织中的表达及其意义 总被引:2,自引:0,他引:2
目的 :探讨热休克蛋白 2 7(HSP2 7)在大肠癌及癌旁组织中的表达及意义。方法 :应用免疫组化S P法检测 72例大肠癌组织和癌旁组织HSP2 7表达情况。结果 :HSP2 7在癌组织与癌旁组织的表达率分别是 4 0 2 8%和 18 75 % ,二者差异有统计学意义 (P <0 0 1)。HSP2 7在高、中、低分化腺癌组织中表达分别是 6 3 6 4 %、31 5 8%和 10 0 0 % ,统计学分析三者之间存在显著性差异 (P <0 0 1)。在大肠癌组织、癌旁组织中HSP2 7表达率与年龄、性别、淋巴结转移、临床分期无相关性 ,但在 >5 0岁组中有 9例呈过表达 (9/ 2 3) ,而≤ 5 0岁组中则无过表达者 ;在伴有淋巴结转移癌组织中HSP2 7表达率为4 3 4 8%。无淋巴结转移者为 38 78% ,统计学分析虽然无显著性差异 (P >0 0 5 ) ,但无淋巴结转移组中HSP2 7有 9例过表达 ,有淋巴结转移组则无 1例过表达。结论 :HSP2 7表达在大肠癌发生过程中发挥重要作用 ,并可能具有抑制肿瘤细胞的恶性转型及防止其侵袭发展作用。 相似文献
68.
Population-based case-control study of CYP11A gene polymorphism and breast cancer risk. 总被引:9,自引:0,他引:9
Wei Zheng Yu-Tang Gao Xiao-Ou Shu Wanqing Wen Qiuyin Cai Qi Dai Jeffrey R Smith 《Cancer epidemiology, biomarkers & prevention》2004,13(5):709-714
The CYP11A gene encodes the cholesterol side-chain cleavage enzyme (P450scc) that catalyzes the first and rate-limiting step for the biosynthesis of sex hormones. A pentanucleotide repeat [(TAAAA)n] polymorphism in the 5' of the CYP11A gene has been reported to be related to the risk of polycystic ovary syndrome, an inherited endocrine disorder characterized by hyperandrogenemia. We investigated the association of this polymorphism with breast cancer risk in a population-based case-control study conducted among Chinese women in Shanghai. Genotype assays were completed for 1015 incident breast cancer cases and 1082 community controls. Three common alleles with 4, 6, or 8 TAAAA repeats were identified in the study population. The frequency of the 8 repeat allele was more common in cases (12.6%) than controls (8.5%) (odds ratio = 1.6, 95% confidence interval = 1.3-1.9; P < 0.0001). Compared to subjects who did not carry this allele, adjusted odds ratios were 1.5 (95% confidence interval = 1.2-1.9) and 2.9 (1.3-6.7) (P for trend, <0.001), respectively, for those who carried one and two copies of this allele. This positive association was observed in both pre- and postmenopausal women and all strata defined by major breast cancer risk factors, including years of menstruation, body mass index, and waist-to-hip ratio. The results from this study indicate that the TAAAA repeat polymorphism near the promoter region of the CYP11A gene may be an important susceptibility factor for breast cancer risk. 相似文献
69.
OBJECTIVE: The goal of this study was to investigate the clinical and paraclinical features, treatment, and outcomes of patients with multiple sclerosis (MS) and coexisting spinal cord compression secondary to either cervical spondylosis or cervical disc disease. Patients with MS commonly experience neurological disabilities that present as myelopathy associated with bladder dysfunction. For some patients with MS, however, this neurological deterioration may result from coexisting spinal cord compression attributable to either spondylosis or a herniated disc. Overlapping symptoms of the two conditions do not allow clear clinical determination of the underlying cause of worsening. METHODS: Patients with MS who underwent cervical decompression surgery were selected. Medical records were retrospectively reviewed, to collect data on their pre- and postoperative clinical courses. RESULTS: Nine women and five men with definite MS were selected for cervical decompression surgery to treat neurological deterioration considered to be at least partially attributable to spinal cord compression. The most common symptoms were progressive myelopathy (n = 13), neck pain (n = 11), and cervical radiculopathy (n = 10). Bladder dysfunction was notably absent among these patients with MS with moderate disabilities. Surgical intervention was frequently delayed because the neurological deterioration was initially thought to be attributable to MS. The majority of patients experienced either improvement or stabilization of their preoperative symptoms in the immediate postoperative period; three subjects (21%) maintained this improvement after a mean follow-up period of 3.8 years. No MS relapses, permanent neurological worsening, or serious complications resulting from surgery or general anesthesia were noted. CONCLUSION: Carefully selected patients with MS and cervical spinal cord compression secondary to either spondylosis or disc disease may benefit from surgical decompression, with minimal associated morbidity. Clinical features (especially neck pain and cervical radiculopathy) and magnetic resonance imaging may assist clinicians in differentiating between the two conditions and may guide appropriate treatment without undue delay. 相似文献
70.
HPLC测定消食止泻散中橙皮苷的含量 总被引:5,自引:0,他引:5
赵彩云 《现代中药研究与实践》2003,17(1):37-38
目的 建立消食止泻散中橙皮苷的含量测定方法。方法 超声提取 ,HPL C测定消食止泻散中橙皮苷的含量。 C1 8柱 ,乙腈 -水 -磷酸 (180∶ 82 0∶ 0 .1)为流动相 ,检测波长为 2 83nm,柱温 :2 8℃。结果 橙皮苷含量测定的线性范围为 0 .197μg~ 1.182μg,r=0 .9999,n=6 ,平均加样回收率为 99.8 ,RSD为 1.3%。结论 本方法准确 ,简便 ,快速 ,可用于消食止泻散的质量控制。 相似文献