首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   27310篇
  免费   2145篇
  国内免费   752篇
耳鼻咽喉   207篇
儿科学   761篇
妇产科学   309篇
基础医学   5219篇
口腔科学   819篇
临床医学   1746篇
内科学   4944篇
皮肤病学   841篇
神经病学   1462篇
特种医学   358篇
外国民族医学   2篇
外科学   2975篇
综合类   3157篇
现状与发展   3篇
预防医学   1174篇
眼科学   330篇
药学   3042篇
  2篇
中国医学   1090篇
肿瘤学   1766篇
  2024年   45篇
  2023年   600篇
  2022年   1314篇
  2021年   1180篇
  2020年   862篇
  2019年   1219篇
  2018年   1194篇
  2017年   1038篇
  2016年   787篇
  2015年   959篇
  2014年   1369篇
  2013年   1491篇
  2012年   1360篇
  2011年   1594篇
  2010年   1238篇
  2009年   1252篇
  2008年   1176篇
  2007年   1137篇
  2006年   1077篇
  2005年   1047篇
  2004年   1004篇
  2003年   955篇
  2002年   745篇
  2001年   590篇
  2000年   576篇
  1999年   476篇
  1998年   422篇
  1997年   402篇
  1996年   294篇
  1995年   265篇
  1994年   262篇
  1993年   206篇
  1992年   145篇
  1991年   144篇
  1990年   105篇
  1989年   104篇
  1988年   90篇
  1987年   60篇
  1986年   61篇
  1985年   213篇
  1984年   191篇
  1983年   113篇
  1982年   150篇
  1981年   124篇
  1980年   123篇
  1979年   111篇
  1978年   101篇
  1977年   63篇
  1976年   56篇
  1974年   42篇
排序方式: 共有10000条查询结果,搜索用时 24 毫秒
991.
Cornelia de Lange syndrome (CdLS) is a clinically heterogeneous disorder characterized by typical facial dysmorphism, cognitive impairment and multiple congenital anomalies. Approximately 75% of patients carry a variant in one of the five cohesin‐related genes NIPBL, SMC1A, SMC3, RAD21 and HDAC8. Herein we report on the clinical and molecular characterization of 11 patients carrying 10 distinct variants in HDAC8. Given the high number of variants identified so far, we advise sequencing of HDAC8 as an indispensable part of the routine molecular diagnostic for patients with CdLS or CdLS‐overlapping features. The phenotype of our patients is very broad, whereas males tend to be more severely affected than females, who instead often present with less canonical CdLS features. The extensive clinical variability observed in the heterozygous females might be at least partially associated with a completely skewed X‐inactivation, observed in seven out of eight female patients. Our cohort also includes two affected siblings whose unaffected mother was found to be mosaic for the causative mutation inherited to both affected children. This further supports the urgent need for an integration of highly sensitive sequencing technology to allow an appropriate molecular diagnostic, genetic counseling and risk prediction.  相似文献   
992.
993.
The T‐helper cell type 2‐promoting cytokine interleukin‐33 (IL‐33) has been implicated in asthma pathogenesis. Angiogenesis is a feature of airways remodelling in asthma. We hypothesized that IL‐33 induces airways angiogenesis and expression of angiogenic factors in an established murine surrogate of asthma. In the present study, BALB/c mice were subjected to serial intranasal challenge with IL‐33 alone for up to 70 days. In parallel, ovalbumin (OVA) ‐sensitized mice were subjected to serial intranasal challenge with OVA or normal saline to serve as positive and negative controls, respectively. Immunohistochemical analysis of expression of von Willebrand factor and erythroblast transformation‐specific‐related gene, both blood vessel markers, and angiogenic factors angiogenin, insulin‐like growth factor‐1, endothelin‐1, epidermal growth factor and amphiregulin was performed in lung sections ex vivo. An established in‐house assay was used to test whether IL‐33 was able to induce microvessel formation by human vascular endothelial cells. Results showed that serial intranasal challenge of mice with IL‐33 or OVA resulted in proliferation of peribronchial von Willebrand factor‐positive blood vessels to a degree closely related to the total expression of the angiogenic factors amphiregulin, angiogenin, endothelin‐1, epidermal growth factor and insulin‐like growth factor‐1. IL‐33 also induced microvessel formation by human endothelial cells in a concentration‐dependent fashion in vitro. Our data are consistent with the hypothesis that IL‐33 has the capacity to induce angiogenesis at least partly by increasing local expression of multiple angiogenic factors in an allergen‐independent murine asthma surrogate, and consequently that IL‐33 or its receptor is a potential novel molecular target for asthma therapy.  相似文献   
994.
Interleukin‐8 (IL‐8) is a pro‐angiogenic cytokine associated with aggressive prostate cancer (CaP). We detected high levels of IL‐8 in sera from patients with CaP compared with healthy controls and patients with benign prostatic hypertrophy. This study examines the role of IL‐8 in the pathogenesis of metastatic prostate cancer. We developed a biocompatible, cationic polylactide (CPLA) nanocarrier to complex with and efficiently deliver IL‐8 small interfering RNA (siRNA) to CaP cells in vitro and in vivo. CPLA IL‐8 siRNA nanocomplexes (nanoplexes) protect siRNA from rapid degradation, are non‐toxic, have a prolonged lifetime in circulation, and their net positive charge facilitates penetration of cell membranes and subsequent intracellular trafficking. Administration of CPLA IL‐8 siRNA nanoplexes to immunodeficient mice bearing human CaP tumours produced significant antitumour activities with no adverse effects. Systemic (intravenous) or local intra‐tumour administration of IL‐8 siRNA nanoplexes resulted in significant inhibition of CaP growth. Magnetic resonance imaging and ultrasonography of experimental animals demonstrated reduction of tumour perfusion in vivo following nanoplex treatment. Staining of tumour sections for CD31 confirmed significant damage to tumour neovasculature after nanoplex therapy. These studies demonstrate the efficacy of IL‐8 siRNA nanotherapy for advanced, treatment‐resistant human CaP.  相似文献   
995.
Schistosoma japonicum infection can induce granulomatous inflammation and cause tissue damage in the mouse liver. The cytokine secretion profile of T helper (Th) cells depends on both the nature of the activating stimulus and the local microenvironment (e.g. cytokines and other soluble factors). In the present study, we found an accumulation of large numbers of IFN‐γ+ IL‐4+ CD4+ T cells in mouse livers. This IFN‐γ+ IL‐4+ cell population increased from 0·68 ± 0·57% in uninfected mice to 7·05 ± 3·0% by week 4 following infection and to 9·6 ± 5·28% by week 6, before decreasing to 6·3 ± 5·9% by week 8 in CD4 T cells. Moreover, IFN‐γ+ IL‐4+ Th cells were also found in mouse spleen and mesenteric lymph nodes 6 weeks after infection. The majority of the IFN‐γ+ IL‐4+ Th cells were thought to be related to a state of immune activation, and some were memory T cells. Moreover, we found that these S. japonicum infection‐induced IFN‐γ+ IL‐4+ cells could express interleukin‐2 (IL‐2), IL‐9, IL‐17 and high IL‐10 levels at 6 weeks after S. japonicum infection. Taken together, our data suggest the existence of a population of IFN‐γ+ IL‐4+ plasticity effector/memory Th cells following S. japonicum infection in C57BL/6 mice.  相似文献   
996.
目的:探讨肌动蛋白样蛋白8(ACTL8)在乳腺癌中的表达及其与乳腺癌临床病理特征及预后的关系。方法:采用Western blot方法检测人正常乳腺上皮细胞株MCF-10A和5种乳腺癌细胞株中ACTL8蛋白的表达;采用免疫组织化学方法检测6例乳腺癌标本及其对应的癌旁组织中ACTL8蛋白的表达;收集TCGA乳腺癌数据集,将488例乳腺标本纳入,分析ACTL8的mRNA表达水平与乳腺癌患者临床病理特征及预后的关系。结果:ACTL8蛋白在乳腺癌细胞株T47D、BT474、HCC1954和SKBR3中表达显著高于乳腺上皮细胞株MCF-10A;ACTL8蛋白在乳腺癌组织中的表达也显著高于癌旁组织;ACTL8 mRNA表达与乳腺癌患者年龄、肿瘤大小、临床TNM分期和淋巴结转移相关(P0.05)。ACTL8 mRNA高表达的乳腺癌患者5年内生存率低、预后差。结论:ACTL8在乳腺癌组织中高表达并与乳腺癌临床病理特征及预后密切相关,提示ACTL8可作为判断乳腺癌预后的标志物。  相似文献   
997.
《Human immunology》2016,77(1):20-28
CD8-positive γδ T lymphocytes (GDCD8+) are specifically increased in peripheral blood of Behçet’s disease (BD) patients. GDCD8+ have shown a T regulatory (Treg) function in autoimmune experimental models, human tumor infiltrates and intestinal intraepithelial lymphocytes from celiac patients. The aim of this study was to evaluate the Treg function of GDCD8+ and GDCD8, freshly isolated from peripheral blood, in comparison to CD4+CD25high naturally occurring Treg cells (nTreg) in BD and healthy controls (HC).We tested their suppressive activity on CD4+CD25 T effector cells (Teff) proliferation by a CFSE dilution protocol, after suboptimal activation with anti-CD3, in the absence or presence of IL-2. Furthermore, secreted cytokines and suppressive latency associated peptide (LAP)-TGFβ surface upregulation were determined after GD activation.We found that Vδ1 chains contribution to GDCD8+ was higher in BD than in HC, but neither GDCD8+ nor GDCD8; (i) suppressed Teff proliferation, (ii) expressed LAP-TGFβ (iii) nor secreted IL-10, in either group. Moreover, GD presented a proinflammatory cytokine profile, mainly producing IFNγ and TNFα, in contrast to nTregs.In conclusion, peripheral GD could contribute more to the dysregulation of TH1 type of cytokines than to exerting a Treg function in BD.  相似文献   
998.
Hemophilia A (HEMA) is an X-linked bleeding disorder caused by mutations in the factor VIII gene (F8C). Molecular genetic testing for the factor VIII gene is challenging due to its large size. Here we present results of high throughput mutation scanning based on Southern blot analysis and direct sequencing of all PCR amplified coding exons and the exon-intron boundaries of the factor VIII gene. The results of mutation analysis on 89 hemophiliac males showed presence of a disease-causing mutation in 80 individuals (90%, 95% CI of 82%-95%). Seven out of nine mutation-negative individuals were severe cases of hemophilia A with < 1% factor VIII protein in the blood. The correlation of phenotype with genotype as observed in this study was not absolute. This finding is supported by similar observations in the international database for hemophilia A mutations (HAMSTeRS). This issue raises the importance of genotypes at other loci that can act as modifiers for the phenotype. Thirty-four novel mutations and three novel substitutions for previously reported amino acid residues were identified in this series of 80 mutations. The mutations cover the full spectrum including rearrangements, deletions, frameshift, and point mutations. The novel missense mutations require careful evaluation. Prediction of a mutation as the disease-causing allele was made from the nature of the substitution and the degree of conservation of the mutated amino acid among species that have diverged in evolution. In some cases segregation analysis of the mutation with disease condition was performed when other family members were available.  相似文献   
999.
目的 探讨血清解整合素样-金属蛋白酶8(ADAM8)、肿瘤标记物癌胚抗原(CEA)与血浆M2型丙酮酸激酶(M2-PK)三者单独及联合检测在非小细胞肺癌(NSCLC)早期诊断中的价值.方法 选取2013年2月至2015年2月间我院收治的NSCLC患者85例纳入非小细胞肺癌组,健康志愿者85例为对照组.采用酶联免疫法(ELISA)分别检测两组患者血清ADAM8及血浆M2-PK水平,并采用电化学发光法(ECMA)检测两组患者的血清CEA水平.结果 两组中各项指标差异均有统计学意义(P<0.01),非小细胞肺癌组患者三种肿瘤标志物的血清阳性率均显著高于对照组(P<0.01),且不同病理类型和临床分期非小细胞肺癌组患者中患者ADAM8、CEA、M2-PK组间比较差异有统计学意义(P<0.05),同时CEA、M2-PK在不同类型的NSCLC中表达量相比差异有统计学意义(P<0.05).三种指标联合检查的灵敏度、特异性以及ROC曲线面积分别为94.1%、92.1%和0.826,显著高于各项指标的单独检测结果.结论 血清ADAM8、CEA及血浆M2-PK对非小细胞肺癌的诊断具有较好的临床价值,而ADAM8、CEA及血浆M2-PK三者联合检测能够显著提高检测的灵敏度,其临床应用价值更高,值得在临床推广使用.  相似文献   
1000.
目的探讨丝裂原活化蛋白激酶(MAPK)信号通路在卵巢癌细胞(SKOV3)诱导CD8+Treg分化过程中的作用。方法建立SKOV3与健康人CD8+T细胞体外共培养体系,设置CD8+T细胞单独培养组为对照组。共培养5 d后,收集各组CD8+T细胞,荧光定量PCR和流式细胞术检测CD8+T细胞中Treg相关标志物(CD25、Foxp3、CD28)的表达率;功能抑制试验检测两组CD8+T细胞对nave CD4+T细胞增殖能力的影响;Western blot检测MAPK通路相关蛋白(ERK/p-ERK、JNK/p-JNK、P38 MAPK/p-P38 MAPK)的表达水平;P38 MAPK特异性抑制剂SB203580预处理CD8+T细胞后,评价CD8+T细胞中Treg相关标志物(CD25、Foxp3、CD28)的表达变化。结果共培养组CD8+T细胞中CD25及Foxp3表达率均显著高于对照组(P0.05),CD28表达率显著低于对照组(P0.05);共培养组CD8+T细胞相比对照组,抑制nave CD4+T细胞的增殖力增强;Western blot结果显示,共培养组p-P38 MAPK的表达水平显著高于对照组(P0.05),SB203580预处理后CD8+T细胞中Treg相关标志物表达率均下调。结论卵巢癌细胞通过活化CD8+T细胞的P38 MAPK信号通路诱导具有抑制作用的CD8+Treg的生成,促进肿瘤进展。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号