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   754篇
  免费   22篇
  国内免费   3篇
耳鼻咽喉   10篇
儿科学   14篇
妇产科学   5篇
基础医学   52篇
口腔科学   35篇
临床医学   42篇
内科学   174篇
皮肤病学   15篇
神经病学   26篇
特种医学   4篇
外科学   196篇
综合类   1篇
预防医学   11篇
眼科学   35篇
药学   26篇
中国医学   1篇
肿瘤学   132篇
  2023年   3篇
  2021年   12篇
  2020年   8篇
  2019年   7篇
  2018年   16篇
  2017年   14篇
  2016年   10篇
  2015年   11篇
  2014年   18篇
  2013年   14篇
  2012年   25篇
  2011年   39篇
  2010年   24篇
  2009年   30篇
  2008年   26篇
  2007年   37篇
  2006年   47篇
  2005年   51篇
  2004年   46篇
  2003年   52篇
  2002年   55篇
  2001年   19篇
  2000年   10篇
  1999年   22篇
  1998年   18篇
  1997年   18篇
  1996年   13篇
  1995年   5篇
  1994年   15篇
  1993年   10篇
  1992年   11篇
  1991年   11篇
  1990年   9篇
  1989年   4篇
  1988年   5篇
  1987年   4篇
  1986年   4篇
  1984年   3篇
  1983年   4篇
  1982年   4篇
  1981年   3篇
  1980年   7篇
  1979年   5篇
  1978年   6篇
  1976年   3篇
  1974年   3篇
  1972年   3篇
  1969年   2篇
  1968年   3篇
  1956年   2篇
排序方式: 共有779条查询结果,搜索用时 0 毫秒
1.
BACKGROUND: To understand the immunopathological features of oral lichen planus (OLP), we analyzed the expression of chemokines in the epithelial cell layers. Methods: Epithelia from OLP or healthy gingiva were collected by laser microdissection. The chemokine and chemokine receptor expressions in the epithelia were analyzed by DNA microarray. RESULTS: High levels of MIP-3alpha/LARC/CCL20 and its receptor CCR6 were expressed in the lesional epithelia. Furthermore, DC-CK1/CCL18, ELC/CCL19, SDF-1/CXCL12 and CXCR4 expressions were also increased. Immunohistologial analysis showed that high numbers of Langerhans cells (LCs) were present in the epithelia of OLP. Lesional epithelia also expressed high levels of the ligands specific for CXCR3 (e.g. MIG/CXCL9, IP-10/CXCL10 and I-TAC/CXCL11) and CCR5 (e.g. RANTES/CCL5). CONCLUSIONS: Infiltration of LCs is orchestrated by CCR6. Further, LCs residing in the lesional epithelia may be a mature phenotype. Moreover, infiltration of T cells in OLP could be mediated by signaling pathways through CXCR3 and CCR5.  相似文献   
2.
We present a 70‐year‐old man who had two episodes of melena during the preceding 8‐year period. He had a Dieulafoy‐like lesion in a diverticulum in the third portion of the duodenum. While emergency endoscopy revealed neither apparent blood nor clots around the diverticular orifice, there was a non‐bleeding vessel in the fundus of the diverticulum. The vessel ceased bleeding after argon plasma coagulation and, since then, the patient has not experienced bleeding. In cases of gastrointestinal bleeding of obscure origin, duodenal diverticulum should be considered as a possible source of bleeding, even when endoscopy discloses no apparent bleeding.  相似文献   
3.
Standard imaging techniques using a curved linear array echoendocope are summarized to facilitate the attainment of expertise in endoscopic ultrasonography and endoscopic ultrasound‐guided fine needle aspiration, and to promote the widespread use of this diagnostic and therapeutic tool. Typical images of the mediastinal organs, the bilio‐pancreatic systems and neighboring organs by scanning from the esophagus, stomach, duodenal bulb, and descending portion of the duodenum, are shown in a sequential manner. The basic techniques of endoscopic ultrasound‐guided fine needle aspiration are also presented.  相似文献   
4.
Summary We recorded visual evoked potentials (VEPs) elicited with high or low imaginable Chinese characters (HIC or LIC), representing concrete objects or absolute concepts, respectively. A closed circle (CC) acts as control stimulus. These were displayed (at 1.6° visual angle) for 35 ms on a TV monitor. Twenty-one channel VEPs (band-pas filter: 0.05–60 Hz), using balanced non-cephalic electrodes, were recorded from –100 to 924 ms for 11 right-handed male volunteers. The VEPs were analyzed by multivariate analysis of variance (MANOVA) and comparison of topographies at four remarkable peaks (P110, N160, P230 and N320). MANOVA showed significant differences (p< 0.001) for both conditions of channel and stimuli (HIC, LIC or CC). P100 for the CC-VEPs, N160 for the HIC-and LIC-VEPs, P230 for the CC-VEPs, and N320 for the HIC-VEPs were remarkable in the posterior scalp regions. Topographies at P100 and N160 showed no difference between the HIC-and LIC-stimuli. However, those at N320 showed difference between the HIC-and LIC-stimuli over the occipital and posterior temporal areas. Those results suggest that the responses at P100 and N160 might segregate Chinese characters from non Chinese characters. N320 suggested certain processes in imagery on recognizing Chinese characters over the occipital and posterior temporal areas.We are grateful to Dr. Yoshiji Kojima of Hamamatsu University for helpful comments.  相似文献   
5.
6.
Arteriovenous anastomoses in the rabbit ear were examined with scanning electron microscopy to elucidate the structural differentiation of the media of the shunt. Arterial, intermediate, and venous segments in the shunt and two layers of the media in the intermediate segment were differentiated based on cell shape and cell organization. In the arterial segment, smooth muscle cells were spindle-shaped, either elongated or short, with a few branches, and were arranged circularly or diagonally with respect to the vessel's long axis. There were also stellate muscle cells with radiating processes. In the intermediate segment, the smooth muscle cells of the outer layer of the media were also arranged circularly and resembled the elongated cells in the arterial segments, but they were more irregular in shape and had more processes than those of the arterial segment. The epithelioid cells of the inner layer of the media were oval or polygonal and oriented irregularly with respect to the vessel's long axis, clustering to form longitudinal plicae. The smooth muscle cells of the venous segment were flat with many lateral processes and formed a thin, discontinuous layer. The smooth muscle cells in the arterial segment and those of the outer layer of the intermediate segment exhibited a highly rugged surface texture, indicating their strong contractility; the epithelioid cells and the smooth muscle cells in the venous segment exhibited a generally smooth surface, indicating less contractility. The intermediate segments were supplied with a dense nerve plexus. The intermediate segments, therefore, may be actively involved in the regulation of blood flow under neuronal influence.  相似文献   
7.
The present study was conducted to compare the pharmacokinetics (PK) of low-dose versus high-dose medroxyprogesterone (MPA) as a once-daily oral administration. Of 32 patients, all women, enrolled in this PK study, 18 received 600 mg MPA daily and 14 received 1200 mg daily. Detailed PK data were obtained on day 1 and after more than 4 weeks of MPA treatment. In addition, multiple data for the minimum steady-state concentration (Css min) were analyzed. The MPA serum concentrations were measured by high-performance liquid chromatography. Wide interpatient variability was found in the PK parameters obtained both on day 1 and after more than 4 weeks. There were no clear relationships between the oral dose and the MPA peak concentration (Cmax), area under the time versus concentration curve (AUC), or mean Css min. Weight gains of 10% or more were demonstrated more frequently in the high-dose group (P<0.01). Liver dysfunction (n=5) did not influence the PK of MPA. Five patients demonstrated extremely low AUC and Cmax (<10 ng/ml) values on day 1. Phenobarbital, dexamethasone and betamethasone were being taken concomitantly with the MPA each by one patient. The serum MPA concentrations were markedly increased after the discontinuation of phenobarbital in that patient, suggesting a drug interaction. At present we cannot recommend the high dose of MPA, except in clinical studies, from a PK or a pharmacodynamic points of view. Received: 2 May 1997 / Accepted: 13 October 1997  相似文献   
8.
We previously designed and synthesized the new nuclear factor kappaB (NF-kappaB) inhibitor dehydroxymethylepoxyquinomicin (DHMEQ) derived from the structure of the antibiotic epoxyquinomicin C. We looked into the effect of DHMEQ on cellular phenotypes and tumor growth in mice injected with human breast carcinoma cell line MDA-MB-231 or MCF-7. In estrogen-independent breast adenocarcinoma cell line MDA-MB-231, NF-kappaB is constitutively activated. The addition of DHMEQ (10 microg/mL) completely inhibited the activated NF-kappaB for at least 8 hours. On the other hand, NF-kappaB is not activated in estrogen-dependent MCF-7 cells. In this cell line, DHMEQ completely inhibited the tumor necrosis factor-alpha-induced activation of NF-kappaB. DHMEQ did not inhibit the degradation of IkappaB but inhibited the nuclear translocation of NF-kappaB by both p65/p50 and RelB/p52 pathways. MDA-MB-231 cells secrete interleukin (IL)-6 and IL-8 without stimulation, and DHMEQ decreased the secretion levels of both cytokines. When MDA-MB-231 or MCF-7 cells were stimulated by tumor necrosis factor-alpha, the inhibitory effects of DHMEQ were still maintained. I.p. administration of DHMEQ (thrice a week) significantly inhibited the tumor growth of MDA-MB-231 (12 mg/kg) or MCF-7 (4 mg/kg) in severe combined immunodeficiency mice. No toxicity was observed during the experiment, including the loss of body weight. An immunohistological study on resected MCF-7 tumors showed that DHMEQ inhibited angiogenesis and promoted apoptosis. Furthermore, in Adriamycin-resistant MCF-7 cells highly expressing multidrug resistance gene-1, DHMEQ also exhibited the above capability, including down-regulation of IL-8. Thus, DHMEQ might be a potent drug for the treatment of various breast carcinomas by inhibiting the NF-kappaB activity.  相似文献   
9.

Purpose

Since the KRAS mutation is not responsible for all metastatic colorectal cancer (mCRC) patients with resistance to anti-epidermal growth factor receptor (EGFR) monoclonal antibody (MoAb) therapy, new predictive and prognostic factors are actively being sought.

Methods

We retrospectively evaluated the efficacy of anti-EGFR MoAb-based therapies in 91 patients with mCRC according to KRAS, BRAF, and PIK3CA mutational status as well as PTEN and MET expression.

Results

In the patient group with wild-type KRAS, the presence of BRAF mutation or PIK3CA mutations was associated with lower disease control rate (DCR), shorter progression-free survival (PFS), and shorter overall survival. Patients with MET overexpression also showed lower DCR and shorter PFS when compared with patients with normal MET expression. In a separate analysis, 44 patients harboring wild-type KRAS tumors were sorted into subgroups of 25 patients without abnormality in three molecules (BRAF, PIK3CA and MET) and 19 patients with abnormality in at least one of these three molecules. The former group showed significantly higher DCR and longer PFS following anti-EGFR therapy than the latter group.

Conclusions

Our data point to the usefulness of MET overexpression, in addition to BRAF and PIK3CA mutations, as a new predictive marker for responsiveness to anti-EGFR MoAbs in mCRC patients with wild-type KRAS. This study also suggests that application of multiple biomarkers is more effective than the use of a single marker in selecting patients who might benefit from anti-EGFR therapy.  相似文献   
10.

Introduction

Microtubule-associated protein tau (MAPT) inhibits the function of taxanes and high expression of MAPT decreases the sensitivity to taxanes. The relationship between estrogen receptor (ER) and MAPT in breast cancer is unclear. In this study, we examined the correlation of MAPT expression with the sensitivity of human breast cancer cells to taxanes, and the relationship between ER and MAPT.

Methods

The correlation between MAPT expression and sensitivity to taxanes was investigated in 12 human breast cancer cell lines. Alterations in cellular sensitivity to taxanes were evaluated after knockdown of MAPT expression. ER expression was knocked down or stimulated in MAPT- and ER-positive cell lines to examine the relationship between ER and MAPT. The cells were also treated with hormone drugs (tamoxifen and fulvestrant) and taxanes.

Results

mRNA expression of MAPT did not correlate with sensitivity to taxanes. However, expression of MAPT protein isoforms of less than 70 kDa was correlated with a low sensitivity to taxanes. Downregulation of MAPT increased cellular sensitivity to taxanes. MAPT protein expression was increased by stimulation with 17-β-estradiol or tamoxifen, but decreased by ER downregulation and by fulvestrant, an ER inhibitor. The combination of fulvestrant with taxanes had a synergistic effect, whereas tamoxifen and taxanes had an antagonistic effect.

Conclusions

Expression of MAPT protein isoforms of less than 70 kDa is correlated with a low sensitivity to taxanes in breast cancer cells. ER influences MAPT expression and fulvestrant increases the sensitivity to taxanes in MAPT- and ER-positive breast cancer cells.  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