全文获取类型
收费全文 | 24185篇 |
免费 | 2582篇 |
国内免费 | 940篇 |
专业分类
耳鼻咽喉 | 442篇 |
儿科学 | 477篇 |
妇产科学 | 583篇 |
基础医学 | 1271篇 |
口腔科学 | 158篇 |
临床医学 | 2434篇 |
内科学 | 4068篇 |
皮肤病学 | 153篇 |
神经病学 | 1499篇 |
特种医学 | 507篇 |
外科学 | 3546篇 |
综合类 | 3905篇 |
预防医学 | 887篇 |
眼科学 | 108篇 |
药学 | 1374篇 |
8篇 | |
中国医学 | 115篇 |
肿瘤学 | 6172篇 |
出版年
2024年 | 66篇 |
2023年 | 401篇 |
2022年 | 1046篇 |
2021年 | 1351篇 |
2020年 | 1280篇 |
2019年 | 1011篇 |
2018年 | 1001篇 |
2017年 | 945篇 |
2016年 | 1048篇 |
2015年 | 1032篇 |
2014年 | 2015篇 |
2013年 | 1626篇 |
2012年 | 1727篇 |
2011年 | 1804篇 |
2010年 | 1375篇 |
2009年 | 1326篇 |
2008年 | 1297篇 |
2007年 | 1242篇 |
2006年 | 1110篇 |
2005年 | 872篇 |
2004年 | 721篇 |
2003年 | 594篇 |
2002年 | 432篇 |
2001年 | 438篇 |
2000年 | 386篇 |
1999年 | 336篇 |
1998年 | 223篇 |
1997年 | 180篇 |
1996年 | 133篇 |
1995年 | 115篇 |
1994年 | 82篇 |
1993年 | 57篇 |
1992年 | 63篇 |
1991年 | 52篇 |
1990年 | 41篇 |
1989年 | 36篇 |
1988年 | 42篇 |
1987年 | 31篇 |
1986年 | 15篇 |
1985年 | 34篇 |
1984年 | 26篇 |
1983年 | 9篇 |
1982年 | 20篇 |
1981年 | 7篇 |
1980年 | 18篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1972年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
背景细菌性肝脓肿(PLA)是临床常见的内脏器官感染性疾病,既往PLA发生血小板减少的临床研究较少。目的 分析PLA患者发生血小板减少的流行病学和临床特征,并探讨发生血小板减少的影响因素。方法 纳入北京大学人民医院2011年1月至2020年12月161例因PLA住院的患者为研究对象。收集患者资料,包括年龄、性别、体质指数(BMI)、发病症状(发热、腹痛、恶心、呕吐)、既往病史信息(高血压、糖尿病、冠心病、肝胆疾病、恶性肿瘤);收集患者入院时辅助检查结果,包括白细胞计数、中性粒细胞绝对值、淋巴细胞绝对值(ALC)、单核细胞绝对值、血红蛋白、C反应蛋白(CRP)、降钙素原(PCT)、丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)、总胆红素(TBiL)、尿素氮(BUN)、肌酐(Scr)、白蛋白(ALB)、凝血酶原时间(PT)、活化部分凝血活酶时间、纤维蛋白原、D-二聚体(D-Dimer)、血小板计数(PLT);收集患者肝脓肿影像学检查(腹部CT或超声)结果(是否多个脓肿)、病原学检查结果(血培养、培养出肺炎克雷伯菌比例);收集患者的并发症情况及预后情况。根据外周血PLT是否<1... 相似文献
102.
转录因子Ascl2作为WNT信号靶基因,可影响结直肠癌(CRC)前体细胞干性特征,探讨其能否调控短链脂肪酸β-氧化而影响CRC患者的预后。方法 下载稳定干扰Ascl2表达的CRC LS174T细胞(sh-Ascl2/LS174T)的mRNA及miRNA差异表达数据(GSE69036和GSE34926)分析其靶基因;应用RT-PCR方法和Western 印迹定量检测sh-Ascl2/LS174T及对照细胞中的Ascl2、Acss1和Acss3的mRNA表达水平,以及Ascl2和Acss1蛋白表达水平,从GSE44076表达数据和UALCAN数据比较在正常结直肠粘膜、CRC组织和不同临床病理分期的肿瘤组织的表达水平差异;TCGA数据库下载548例CRC患者基因 mRNA表达量及相关临床信息,用Spearman等级相关分析表达相关性,Kaplan-Meier法进行生存分析,Cox回归分析评估危险因素。结果 sh-Ascl2/LS174T细胞中Acss1的mRNA较对照细胞下调2.08倍,miR-4282表达水平下调2.069倍。RT-PCR定量检测sh-Ascl2/LS174T细胞中Acss1的mRNA和miR-4282水平明显下降(P<0.01), Acss3的mRNA水平明显升高(P<0.05);Acss1和Ascl2蛋白水平较对照细胞均明显下降。CRC组织Ascl2和Acss1的mRNA水平明显高于癌旁结直肠粘膜组织(P<0.001),而Acss3明显低于癌旁结直肠粘膜组织 (P<0.001);CRC组织中Ascl2与Acss1的mRNA表达水平呈正相关,与Acss3的表达水平呈负相关(均P<0.001)。Ascl2和Acss3表达水平与疾病特异性生存期(DSS)、总体生存期(OS)、无进展生存期(PFS)无关,Acss1高表达组比低表达组的DSS (P=0.0389)和OS (P=0.04)明显降低。Ascl2与Acss1基因异常表达、Ascl2、Acss1和Acss3基因异常联合表达与CRC患者的DSS存在显著的联系(P=0.0377和P=0.0161),Ascl2、Acss1和Acss3三个基因的联合异常表达是影响CRC患者DSS的危险因素之一(P=0.043)。结论Ascl2对CRC细胞中的Acss1/3的表达可能具有调控作用而导致其短链脂肪酸β-氧化的重编程,它们的联合异常表达可以一定程度预测CRC患者的预后 相似文献
103.
探讨中性粒细胞与淋巴细胞比值(NLR)对≥80岁急性缺血性脑卒中患者90 d预后的价值。方法 纳入2019年1月—2021年6月发病7 d内、≥80岁的缺血性卒中患者476例的相关信息、影像结果、随访结果,按照入组患者NLR的四分位数间距分为Q1组(NLR <2.97)、Q2组( 2.97≤NLR <4.49)、Q3组( 4.49≤NLR <7.94)、Q4组 (NLR≥7.94),每组119例。根据不良结局发生率绘制K-M曲线,比较各组在不同时期的生存概率。采用Cox多因素回归分析影响患者不良预后的因素。结果log-rank检验显示,四组患者的生存率存在差异,Q4组的90 d生存率显著低于Q1组(P<0.05)。多因素Cox回归分析显示,校正危险因素后,高NLR和高NIHSS评分是90 d死亡率的独立危险因素(P<0.05)。根据ROC曲线,高NLR预测患者90 d死亡曲线下面积为0.74。结论 高NLR为影响≥80岁高龄急性缺血性卒中患者90 d预后的独立危险因素,对高龄急性缺血性脑卒中患者的90 d预后有预测价值 相似文献
104.
Nae Yu Kim Jung-Soo Pyo Dong-Wook Kang Seung-Min Yoo 《Pathology, research and practice》2019,215(3):580-585
Objective
The aim of this study was to elucidate the clinicopathological significance and prognostic role of loss of claudin-1 in colorectal cancer (CRC).Methods
The correlations between claudin-1 expression and clinicopathological characteristics, including survival rates, were assessed using immunohistochemistry on 260 archival, paraffin-embedded CRC tissues. In addition, the correlations between cludin-1 and nuclear factor-kappa B (NF-κB), epithelial-mesenchymal transition markers and tumor-infiltrating lymphocytes were investigated.Results
Claudin-1 expression was markedly lost in 42.7% of the 260 CRCs analyzed. Loss of claudin-1 expression significantly correlated with larger tumor size, vascular invasion, higher pT stage, and high metastatic lymph node ratio. In addition, loss of claudin-1 expression significantly correlated with NF-κB activation (P?<?0.001), high SNAI (P?<?0.001), and low E-cadherin (P?<?0.001) expressions. Patients with high immunoscores showed significantly lower rates of claudin-1 expression loss (P?=?0.020). In detail, loss of claudin-1 expression were frequently found in CRCs low CD3- and CD8-positive lymphocytes. There were significant correlations between claudin-1 expression loss and poor overall and recurrence-free survivals (P?<?0.001 and P?<?0.001, respectively).Conclusion
Taken together, our results suggest that the loss of claudin-1 expression significantly correlates with aggressive tumor behaviors, high SNAI expression, lower immunoscore, and poor prognoses. 相似文献105.
K. M. Mitchell R. J. Hale C. H. Buckley H. Fox D. Smith 《Virchows Archiv : an international journal of pathology》1993,422(5):357-360
An immunohistochemical study was made of cathepsin-D protein expression in each of the three main types of uterine cervical carcinoma (squamous carcinoma, adenosquamous carcinoma and adenocarcinoma) with particular reference to lymph node status and prognosis. Of the 61 cases, 54.1% showed cytoplasmic staining in more than 2.5% of tumour cells counted. Cathepsin-D expression was significantly higher in adenocarcinoma (mean -3.128) than in squamous carcinoma and adenosquamous carcinoma (mean –3.709,P=0.047 using logit transformation). Cathepsin-D had no prognostic value in any of the three tumour types. No relationship was found between cathepsin-D staining and lymph node status and there was no advantage in adding cathepsin-D values to lymph node status. These results suggest that immunostaining for cathepsin-D protein expression is unlikely to be of use as a prognostic marker. 相似文献
106.
增殖细胞核抗原表达与AgNORs图像分析在判断肺癌预后上的应用 总被引:19,自引:0,他引:19
应用抗增殖细胞核抗原(抗PCNA)单克隆抗体,采用S-P免疫组化方法和AgNORs染色图像分析,对有确切随访结果的86例原发性肺癌和10例肺炎性假瘤进行了研究。结果表明:经PC-NA阳性反应计算出的增殖指数(PI)与图像分析的AgNORs计数及其颗粒总面积间存在着明显的相关性。二者均与肺癌分型有关,并随癌分化程度的增高而减小;与TNM分期中的淋巴结(N)和远隔转移(M)有关;术后存活5年以上者明显小于3年以内者(P<0.01)。认为PCNA的表达和AgNORs图像分析技术有助于肺癌的分型、分化及预后的判断。 相似文献
107.
成人小脑髓母细胞瘤的临床及病理研究 总被引:4,自引:0,他引:4
目的探讨成人小脑髓母细胞瘤的临床病理特点、组织发生学及影响预后的因素。方法对我院1974~1995年间27例成年人(≥16岁)小脑髓母细胞瘤进行了观察。结果本组年龄16~55岁,平均25.8岁,肿瘤发生于小脑蚓部21例,小脑半球6例。随访21例,7例已生存2.5~17年,14例死亡。平均生存时间41.6个月。1年生存率为71.4%,5年及10年生存率均14.3%。组织学类型:经典型14例,促纤维增生型13例。结论通过电镜观察及突触素、神经元特异性烯醇化酶和胶质纤维酸性蛋白免疫组化染色观察,证实髓母细胞瘤是具有向神经元及胶质细胞双向分化潜能的原始神经外胚叶肿瘤。影响预后的因素包括年龄、肿瘤部位、治疗手段以及组织学类型 相似文献
108.
Sang-Hyun Cho Dong Gyu Kim Dae-Shik Kim Yun-Hee Kim Chu-Hee Lee Sung Ho Jang 《Neuroscience letters》2007
Diffusion tensor tractography (DTT) is useful for exploring the state of the corticospinal tract (CST). An accurate estimation of the integrity of the CST in the early stage of a cerebral infarct would enable a determination of motor recovery. DTT was performed to classify CST integrity following a corona radiata infarct to evaluate if the procedure could characterize the motor outcome of the affected hand. Fifty-five patients with completely paralyzed hands due to a corona radiata infarct were recruited for the study, and DTT images were obtained within 7–30 days after a stroke. The DTI findings for the patients were classified into four groups. In type A, the CST was preserved around the infarct; in type B, the CST originated from a cortex other than the primary motor cortex; in type C, the CST was interrupted at the infarct; in type D, the CST failed to reach the infarct due to degeneration. Six months after a stroke, the motor function of the affected hand was evaluated with the motricity index (MI) for the hand, the Medical Research Council score (MRC) for finger extensors and the modified Brunnstrom classification (MBC). These indices were significantly influenced by the DTT type (p < 0.05). The highest MI, MRC and MBC were seen in the DTT type A patients; the lowest MI, MRC and MBC were seen in the DTT type D patients (p < 0.05). The integrity of the corticospinal tract determined by DTT obtained during the early stage of a corona radiata infarct seems to be helpful in predicting the motor outcome of the affected hand. 相似文献
109.
Clinicopathological significant and prognostic influence of cadherin-17 expression in gastric cancer 总被引:5,自引:0,他引:5
Ito R Oue N Yoshida K Kunimitsu K Nakayama H Nakachi K Yasui W 《Virchows Archiv : an international journal of pathology》2005,447(4):717-722
Cadherin-17 (CDH17), also called liver–intestine cadherin, is a structurally unique member of the cadherin superfamily. Our
serial analysis of gene expression demonstrated that CDH17 was one of the most up-regulated genes in advanced gastric carcinomas.
CDH17 expression is known to be regulated by Cdx2. In the present study, we examined the expression of CDH17 in primary gastric
carcinoma tissues by immunohistochemistry, and analyzed the correlation of CDH17 expression with clinicopathological characteristics
and patients prognosis. CDH17 expression was detected in 63/94 (67%) of gastric adenocarcinomas in addition to intestinal
metaplasia. The expression of CDH17 tended to be associated with intestinal type carcinoma, and carcinomas with CDH17 expression
was significantly more frequent in advanced stage cases (80%) than in early stage (53%). The prognosis of patients with positive
CDH17 expression was significantly poorer than that of the negative cases (P=0.0314). However, multivariate analysis revealed that CDH17 was not an independent prognostic factor. Six of seven cases
that showed positive expression of Cdx2 simultaneously expressed CDH17 protein. These results suggested that the expression
of CDH17 was characteristic of the advanced gastric carcinoma that is associated with poor prognosis. 相似文献
110.
目的 观察胃癌组织中cNOSmRNA表达分布情况 ,探讨其与胃癌侵袭转移和预后的关系。 方法 运用原位杂交技术 ,检测 119例原发性胃癌标本中cNOSmRNA的表达 ,并对所获得的 82份病例随访资料进行生存分析。 结果 胃癌组织中胃腺癌细胞、血管 淋巴管内皮细胞及巨噬细胞中均可见有cNOSmRNA表达 ;肿瘤细胞分化程度越低、恶性度越高 ,胃腺癌细胞和血管 淋巴管内皮细胞cNOSmRNA阳性表达率就越高 ;胃腺癌细胞和血管 淋巴管内皮细胞cNOSmRNA阳性表达率与胃癌侵袭深度、淋巴结转移以及TNM分期呈正相关 ;胃癌血管 淋巴管内皮细胞cNOSmRNA阳性表达者术后生存率较低 ;巨噬细胞中cNOSmRNA表达与胃癌组织学分型、侵袭深度、淋巴结转移、TNM分期及患者术后生存期无关。 结论 胃腺癌细胞和血管 淋巴管内皮细胞cNOSmRNA表达情况与肿瘤恶性程度、侵袭和转移潜能有关 ,血管 淋巴管内皮细胞上cNOSmRNA阳性表达提示患者预后不良 相似文献