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   112266篇
  免费   10576篇
  国内免费   6364篇
耳鼻咽喉   1229篇
儿科学   1453篇
妇产科学   968篇
基础医学   11688篇
口腔科学   1972篇
临床医学   12864篇
内科学   14079篇
皮肤病学   1746篇
神经病学   4527篇
特种医学   5285篇
外国民族医学   21篇
外科学   11211篇
综合类   21673篇
现状与发展   34篇
一般理论   7篇
预防医学   9155篇
眼科学   2772篇
药学   12621篇
  125篇
中国医学   7650篇
肿瘤学   8126篇
  2024年   1089篇
  2023年   1511篇
  2022年   3566篇
  2021年   4791篇
  2020年   3772篇
  2019年   2930篇
  2018年   3146篇
  2017年   3282篇
  2016年   3168篇
  2015年   4940篇
  2014年   6314篇
  2013年   6750篇
  2012年   9648篇
  2011年   10223篇
  2010年   7454篇
  2009年   6591篇
  2008年   7583篇
  2007年   7321篇
  2006年   6720篇
  2005年   5644篇
  2004年   4229篇
  2003年   3942篇
  2002年   3202篇
  2001年   2304篇
  2000年   1863篇
  1999年   1415篇
  1998年   813篇
  1997年   729篇
  1996年   627篇
  1995年   563篇
  1994年   534篇
  1993年   353篇
  1992年   384篇
  1991年   354篇
  1990年   295篇
  1989年   265篇
  1988年   175篇
  1987年   195篇
  1986年   147篇
  1985年   102篇
  1984年   55篇
  1983年   40篇
  1982年   38篇
  1981年   27篇
  1980年   28篇
  1979年   17篇
  1978年   6篇
  1975年   7篇
  1973年   10篇
  1972年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.

Background/Aims

Transarterial chemoembolization (TACE) has long been used as a palliative therapy for unresectable hepatocellular carcinoma (HCC). High-dose hepatic arterial infusion chemotherapy (HAIC) has showed favorable outcomes in patients with intractable, advanced HCC. The aim of this study was to compare the effectiveness and safety of high-dose HAIC and conventional TACE using doxorubicin for advanced HCC.

Methods

The high-dose HAIC group comprised 36 patients who were enrolled prospectively from six institutions. The enrollment criteria were good liver function, main portal vein invasion (including vascular shunt), infiltrative type, bilobar involvement, and/or refractory to prior conventional treatment (TACE, radiofrequency ablation, or percutaneous ethanol injection), and documented progressive disease. Patients received 5-fluorouracil (500 mg/m2 on days 1~3) and cisplatin (60 mg/m2 on day 2 every 4 weeks) via an implantable port system. In the TACE group, 31 patients with characteristics similar to those in the high-dose HAIC group were recruited retrospectively from a single center. Patients underwent a transarterial infusion of doxorubicin every 4~8 weeks.

Results

Overall, 6 patients (8.9%) achieved a partial response and 20 patients (29.8%) had stable disease. The objective response rate (complete response+partial response) was significantly better in the high-dose HAIC group than in the TACE group (16.7% vs. 0%, P=0.030). Overall survival was longer in the high-dose HAIC group than in the TACE group (median survival, 193 vs. 119 days; P=0.026). There were no serious adverse effects in the high-dose HAIC group, while hepatic complications occurred more often in the TACE group.

Conclusions

High-dose HAIC appears to improve the tumor response and survival outcome compared to conventional TACE using doxorubicin in patients with intractable, advanced HCC.  相似文献   
992.
993.
目的: 观察电离辐射对体外培养的IEC -6细胞株生长的影响及IL- 2对其损伤后增殖和恢复的作用, 并进一步探讨肠黏膜免疫与肠上皮辐射损伤及修复的关系。方法: 用 4、8、12Gy的γ射线照射IEC- 6细胞株, 并于照后 3、6、9、12h及 1、2、3d, 用MTT比色法、光镜、电镜、DNA凝胶电泳和流式细胞术等, 检测受照射后IEC- 6细胞的增殖活力、形态和死亡方式的改变; 用不同浓度IL 2 ( 25×103、5×104、1×105U/L)处理 8Gyγ射线照射的IEC 6细胞, 并于照射后 3、6、9、12、24h, 采用MTT比色法检测其增殖活力的变化。结果: 在 0~12Gy的范围内, IEC 6细胞的增殖活力随γ射线照射剂量的增加而降低。8. 0γ射线照后 24h, 凋亡的IEC- 6细胞明显增多, DNA凝胶电泳显示有梯状带形成。IL- 2可促进照射后的IEC- 6细胞增殖且呈一定的剂量 效应关系, 尤以1×105U/L组的作用更明显。结论: 在一定剂量范围内, γ射线照射可降低IEC 6细胞增殖活力, 且存在剂量 效应关系;可导致IEC 6细胞发生凋亡。IL- 2可促进受照射的IEC- 6细胞增殖, 增强其抗辐射的作用。  相似文献   
994.
目的:检测转化生长因子β1(TGFβ1)对大鼠肺成纤维细胞(RLF)中转录因子SP1、AP1和Smad3-Smad4活性的影响并探讨其意义。方法:进行大鼠肺成纤维细胞的原代分离培养,应用10μg/L TGFβ1进行处理,通过凝胶阻滞电泳(EMSA)、免疫印迹和免疫组化染色等方法,检测照射后转录因子SP1、AP1和Smad3-Smad4活性的变化及Ⅰ型胶原和Ⅰ型组织纤溶酶原激活物抑制剂(plasminogen activator inhibi-torⅠ,PAI-1)表达的变化。结果:正常RLF中AP1和Smad3-Smad4形成弱阻滞条带,SP1无阻滞条带形成。以10μg/LTGFβ1处理后,3种转录因子所形成的阻滞条带明显增强,PAI-1和Ⅰ型胶原的表达增多。结论:一定浓度的TGFβ1可促进RLF中转录因子SP1、AP1和Smad3-Smad4的活化,并进而增加PAI-1和Ⅰ型胶原的表达。  相似文献   
995.
We have used gene expression profiling approaches to identify new molecular targets in various models of lung injury and human lung diseases. Among the many genes that are significantly induced in these studies, cysteine-rich61 (Cyr61) consistently ranks as one of the most significant genes. Here, we use the well-established model of hyperoxia to better understand the function of Cyr61 in acute lung injury. Cyr61, a stress-related immediate-early response gene, has known diverse functions involving angiogenesis, tumorigenesis, and wound repair. It belongs to the newly discovered "CCN" family containing six growth and regulatory factors. We showed that hyperoxia induces Cyr61 expression in a variety of pulmonary cells and in lung tissue in vivo. Loss of function studies, by suppressing Cyr61 expression by siRNA, accelerated lung epithelial cell death after hyperoxia. Gain of function studies, by overexpressing Cyr61, significantly conferred increased resistance to hyperoxia-induced cell death. Moreover, cells overexpressing Cyr61 induce Akt activation. Inhibition of Akt by siRNA abrogated the protective effects of Cyr61-overexpressing cells in response to hyperoxia. Taken together, our data demonstrate that Cyr61 expression provides cytoprotection in hyperoxia-induced pulmonary epithelial cell death and that this effect was in part mediated via the Akt signaling pathway.  相似文献   
996.
护理人力资源管理是人力资源中的微观管理内容,分析当前我国护理人力资源的管理现状,不难发现还存在着诸多问题,例如:工作压力过大、人员不足、工作满意度低、队伍整体素质水平有待提高等。那么,如何及时有效的运用科学的管理模式解决这些问题,从而提高护士们的工作积极性与能动性,是每一名护理管理人员迫在眉睫的新课题。本文就当前国内医院护理人力资源管理以及护士工作的满意程度现状进行了分析,并提出了有效的完善措施,希望能够为我国护理人力资源的可持续发展提供更为坚实可靠的保障。  相似文献   
997.
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the presence of antinucleic acid autoantibodies, high levels of circulating type I interferon (IFN‐I), and an IFN‐I‐dependent elevated expression of activating FcγR. Increases in neutrophils and monocytes are often observed in clinical SLE, but how these contribute to autoantibody and IFN‐I production is poorly understood. Here, we analyzed SLE pathogenesis in 564Igi mice, an SLE‐model strain carrying gene‐targeted heavy and light chain antibody genes encoding an anti‐RNA autoantibody in a C57BL/6 background. Similar to human SLE patients, 564Igi mice produce anti‐RNA autoantibodies and expanded neutrophil and monocyte populations. These myeloid cells produced IFN‐I and exhibit increased FcγRIV expression induced via an IFN‐I autocrine loop. A direct effect of IFN‐I on 564Igi BM B cells and neutrophils was supported by their upregulation of “IFN‐I signature genes”. In addition, 564Igi developing B cells showed upregulated TLR7 resulting in IgG2a/2b class switch recombination and autoantibody production. Our results indicate that the production of anti‐RNA autoantibody is sufficient to induce an increase of BM, blood, and spleen IFN‐I‐producing neutrophils, and suggest a mechanism by which autoantibody and IFN‐I contribute to SLE by activating B lymphocytes, neutrophils, and monocyte effector cells in vivo.  相似文献   
998.
We isolated and characterized three multidrug-resistant clinical isolates of group B streptococci with reduced penicillin susceptibility (PRGBS) that formed small non-beta-hemolytic colonies on sheep blood agar plates but grew well on chocolate agar plates. They can be overlooked in the bacterial identification step, leading to clinical misdiagnosis and treatment failure.  相似文献   
999.
Sparganosis is a parasitic infestation of human by plerocercoid larvae. Sparganum is usually reported to be found in the subcutaneous tissues as well as other organs, including scrotum. However, testicular sparganosis is extremely rare, because of strong capsule of tunica albuginea. An urban-living 54-yr-old Korean man presented with left scrotal pain for 6 yr. Both testes look normal physically. Ultrasonography revealed poorly defined, heterogeneous mass with increased echogenicity in the left testis. This case was misdiagnosed as testicular tumor and underwent orchiectomy, but was diagnosed as testicular sparganosis by histopathology. Sparganosis should be included for differential diagnosis of testis tumor in countries where sparganosis is prevalent.

Graphical Abstract

相似文献   
1000.

PURPOSE:

To compare the characteristics of tubercular vs. leukemic involvement of abdominopelvic lymph nodes using multidetector computed tomography (CT).

MATERIALS AND METHODS:

We retrospectively reviewed multidetector computed tomography features including lymph node size, shape, enhancement patterns, and anatomical distribution, in 106 consecutive patients with newly diagnosed, untreated tuberculosis (55 patients; 52%) or leukemia (51 patients; 48%). In patients with leukemia, 32 (62.7%) had chronic lymphocytic leukemia, and 19 (37.3%) had acute leukemias; of these, 10 (19.6%) had acute myeloid leukemia, and 9 (17.6%) had acute lymphocytic leukemia.

RESULTS:

The lower para-aortic (30.9% for tuberculosis, 63.2% for acute leukemias and 87.5% for chronic lymphocytic leukemia) and inguinal (9.1% for tuberculosis, 57.9% for acute leukemias and 53.1% for chronic lymphocytic leukemia) lymph nodes were involved more frequently in the three types of leukemia than in tuberculosis (both with p <0.017). Tuberculosis showed peripheral enhancement, frequently with a multilocular appearance, in 43 (78.2%) patients, whereas patients with leukemia (78.9% for acute myeloid leukemia and acute lymphocytic leukemia, 87.5% for chronic lymphocytic leukemia) demonstrated predominantly homogeneous enhancement (both with p <0.017). For the diagnosis of tuberculosis, the analysis showed that a peripheral enhancement pattern had a sensitivity of 78.2%, a specificity of 100%, and an accuracy of 88.7%. For the diagnosis of leukemia, the analysis showed that a homogeneous enhancement pattern was associated with a sensitivity of 84.3%, a specificity of 94.5%, and an accuracy of 89.6%.

CONCLUSION:

Our findings indicate that the anatomical distribution and enhancement patterns of lymphadenopathy seen on multidetector computed tomography are useful for differentiating between untreated tuberculosis and leukemia of the abdominopelvic lymph nodes.  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