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   1196篇
  免费   41篇
  国内免费   6篇
耳鼻咽喉   4篇
儿科学   3篇
妇产科学   12篇
基础医学   118篇
口腔科学   30篇
临床医学   49篇
内科学   243篇
皮肤病学   5篇
神经病学   63篇
特种医学   219篇
外科学   245篇
综合类   12篇
预防医学   14篇
眼科学   7篇
药学   40篇
肿瘤学   179篇
  2023年   4篇
  2022年   4篇
  2021年   18篇
  2020年   4篇
  2019年   18篇
  2018年   19篇
  2017年   15篇
  2016年   13篇
  2015年   22篇
  2014年   28篇
  2013年   29篇
  2012年   60篇
  2011年   88篇
  2010年   35篇
  2009年   37篇
  2008年   58篇
  2007年   65篇
  2006年   66篇
  2005年   64篇
  2004年   73篇
  2003年   74篇
  2002年   77篇
  2001年   28篇
  2000年   32篇
  1999年   27篇
  1998年   26篇
  1997年   18篇
  1996年   14篇
  1995年   17篇
  1994年   12篇
  1993年   5篇
  1992年   19篇
  1991年   12篇
  1990年   14篇
  1989年   22篇
  1988年   24篇
  1987年   9篇
  1986年   10篇
  1985年   11篇
  1984年   8篇
  1983年   4篇
  1982年   8篇
  1981年   5篇
  1979年   9篇
  1978年   3篇
  1977年   10篇
  1976年   6篇
  1975年   6篇
  1974年   3篇
  1973年   4篇
排序方式: 共有1243条查询结果,搜索用时 15 毫秒
1.
We report a newly developed MR simulation system for intracavitary brachytherapy for cervical cancer and subsequent treatment results. MR simulation was performed on six patients. The spatial relationship of the tumor to the bladder, rectum, bowel, applicators, etc. was depicted well. Doses to the tumor and surrounding normal tissues were read from isodose curves superimposed on the T2-weighted sagittal image. This system promises to be useful in customizing the dose distribution.  相似文献   
2.
3.
Chronotropic and inotropic effects of histamine were examined in isolated atrial and ventricular preparations from embryonic and hatched chicken hearts. Histamine produced positive chronotropic and inotropic responses both in embryonic and hatched hearts. The responses to histamine in middle embryonic myocardia, which were observed in the micromolar range, were antagonized by H2 antagonists but not by H1, H3 antagonists and propranolol. Isobutylmethylxantine, an inhibitor of phosphodiesterase, produced a leftward shift of the concentration-response curve for the chronotropic effect of histamine in the embryo. The responses to histamine in myocardia from hatched chicks, which were observed in the milimolar range, appeared concurrently with the responses to tyramine during development and were antagonized by beta adrenoceptor antagonists but not by any of the histamine antagonists. The positive inotropic response to histamine in hatched ventricular preparations were greatly attenuated by reserpine pretreatment or in the presence of desipramine. Thus, we demonstrated that exogenously applied histamine produces positive chronotropic and inotropic responses in developing chicken hearts and that the mechanisms are different between embryonic and hatched chicks: direct action on H2 receptors in the embryonic heart and release of norepinephrine from sympathetic nerve terminals in hatched hearts.  相似文献   
4.
OBJECTIVES: To determine the prevalence of periapical radiolucencies and endodontic treatment in an adult Japanese population. STUDY DESIGN: Periapical status and length of root fillings of 672 adult patients attending Okayama University Hospital of Dentistry were evaluated using full mouth intraoral radiographs. RESULTS: Overall, 87% of the subjects had root-filled teeth, and 70% exhibited an apical radiolucency. Of the 16,232 teeth examined, 21% had been root-filled, and, of these, 40% exhibited an apical radiolucency. Root-filled teeth that were overfilled or that were mandibular incisors had the highest prevalence of apical radiolucencies. CONCLUSIONS: The prevalence of root-filled teeth appears higher in this Japanese population than in Europe or America; however, the ratio of teeth with an apical radiolucency to root-filled teeth was within the range of that reported for other countries. Overfilled teeth and mandibular incisors are most likely to exhibit apical radiolucencies.  相似文献   
5.
An autopsy case of pulmonary candidiasis occurring in a neonatal girl was reported. The mycological examination of the lung taken at autopsy revealed only Candida albicans and followed by the elucidation under the microscopic sections prepared with special stains; periodic acid-Schiff and methenamine silver, in the lung, stomach, umbilical cord, and amnion. The presence of Candida vaginitis in her mother supported the concept that Candida albicans was the etiological agent of the pulmonary candidiasis.  相似文献   
6.
7.
Trefoil factor family 2 (TFF2) is a small peptide constitutively expressed in the gastric mucosa, where it plays a protective role in restitution of gastric mucosa. TFF2 has also been shown to be expressed in some gastric cancers, but its role in tumor metastasis and patient prognosis has not been examined. In this study, we examined TFF2 expression at both the mRNA and protein levels and correlated these results with the clinicopathologic characteristics and prognosis of gastric cancer patients. Among the 144 curatively resected samples, 43 (30%) were positive for TFF2. TFF2 expression was preferentially observed in the infiltrating tumor cells sparing the superficial cells. Significantly increased expression of TFF2 was noted in large tumors of the diffuse type. An increased prevalence of TFF2 expression was also found in tumors with advanced T and N stage and in patients with lymphatic and venous invasion. Accordingly, patients with TFF2-expressing tumors had a significantly worse disease-free survival, and in multivariate analysis, this finding remained significant as an independent prognostic factor. Taken together, our results suggest that TFF2 expression may play a role in gastric cancer invasion and as such could be a useful target for therapeutic intervention.  相似文献   
8.
Studies have suggested that psoriasis vulgaris is mediated by type 1 T cells. In this study, we examined both chemokine receptor expression and intracellular cytokine production by circulating T cells to check the type 1/type 2 balance in psoriasis. CCR4+ and CXCR3+ T cells predominantly produced interleukin-4 and interferon-, respectively. The frequency of interferon--producing cells and that of CXCR3+ cells in circulating CD4+ T cells were similar for psoriatic patients and healthy control subjects. By contrast, the frequency of CCR4+CD8+ T cells and CCR4/CXCR3 ratio in circulating CD8+ T cells were significantly higher in psoriatic patients than in healthy control subjects. Analysis of intracellular cytokine production also indicated relative increase of type 2 CD8+ T (Tc2) cells in peripheral blood from psoriatic patients. The frequency of circulating Tc2 cells directly correlated with Psoriasis Area and Severity Index. Immunohistochemical analysis showed that not only CXCR3+CD8+ T cells but also a similar number of CCR4+CD8+ T cells infiltrated the psoriatic epidermis and dermis. Our findings suggest an increase in Tc2 cell number in blood from psoriatic patients, and the association of Tc2 cells with inflammation in psoriasis.  相似文献   
9.
10.
Although estrogen is known to play a crucial role in the pathogenesis of breast cancer, the molecular mechanisms underlying the action of estrogen remain elusive. In the present study, we focused on keratinocyte growth factor (KGF) and its receptor (KGFR) in the pathogenesis of breast cancer, as a growth factor mediating estrogen action, since significant roles of KGF were demonstrated in various steroid hormone-dependent tissues. First, using paraffin-embedded specimens from 42 breast cancer patients, we examined expression patterns of KGF and KGFR by both immunohistochemistry using newly generated antibodies and nonradioactive in situ hybridization with T-T dimerized synthetic oligonucleotide probes. We next compared the results with the expression of estrogen receptor (ER) alpha and beta, proliferative activity and apoptotic frequency (TUNEL staining). Also, the similar approaches were taken to analyze the expression and role of KGF in ER-positive (MCF7, ZR-75-1) and ER-negative (SK-BR-3, MDA-MB-231) human breast cancer cell lines in vitro. In the surgical specimens, KGF was expressed in cancer cells as well as stromal cells in 19/42 cases (45%), while KGFR was found in cancer cells in 24/42 cases (57%). The distribution of protein and mRNA in the analysis of both KGF and KGFR expression generally coincided. Moreover, KGF expression was closely associated with the expression of ER alpha, and the coexpression of KGF and KGFR significantly correlated with lower TUNEL index, but not with proliferative activity. In accordance with the in vivo findings, KGF expression was detected only in ER alpha-positive MCF7 and ZR-75-1 cells in vitro. And more importantly, we found the inhibitory effect of KGF upon the induction of apoptosis by anticancer drugs in MCF7 cells. Collectively, our results indicate that ER alpha may be involved in KGF expression, and that KGF may play antiapoptotic roles, rather than mitogenic, in human breast cancer.  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