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   11099篇
  免费   597篇
  国内免费   104篇
耳鼻咽喉   103篇
儿科学   259篇
妇产科学   109篇
基础医学   1068篇
口腔科学   175篇
临床医学   759篇
内科学   3074篇
皮肤病学   150篇
神经病学   661篇
特种医学   392篇
外科学   2237篇
综合类   65篇
预防医学   246篇
眼科学   152篇
药学   741篇
中国医学   19篇
肿瘤学   1590篇
  2023年   90篇
  2022年   173篇
  2021年   310篇
  2020年   190篇
  2019年   239篇
  2018年   271篇
  2017年   249篇
  2016年   291篇
  2015年   315篇
  2014年   368篇
  2013年   441篇
  2012年   748篇
  2011年   773篇
  2010年   449篇
  2009年   366篇
  2008年   606篇
  2007年   648篇
  2006年   673篇
  2005年   692篇
  2004年   657篇
  2003年   659篇
  2002年   653篇
  2001年   180篇
  2000年   159篇
  1999年   181篇
  1998年   120篇
  1997年   98篇
  1996年   93篇
  1995年   83篇
  1994年   88篇
  1993年   74篇
  1992年   91篇
  1991年   112篇
  1990年   72篇
  1989年   89篇
  1988年   81篇
  1987年   52篇
  1986年   44篇
  1985年   35篇
  1984年   34篇
  1983年   36篇
  1982年   19篇
  1980年   14篇
  1979年   31篇
  1978年   13篇
  1976年   9篇
  1973年   11篇
  1971年   15篇
  1969年   16篇
  1966年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
We examined the anti-tumor effect of a novel benzoic acid derivative, TAC-101 (4-[3,5-bis(trimethylsilyl) benzamide] benzoic acid) on models with liver metastasis. Oral administration of TAC-101 significantly inhibited spontaneous liver metastasis of AZ-521 (human gastric cancer ) by orthotopic implan-tation to athymic nude mice. It also inhibited both the liver metastasis of AZ-521 induced by intrasplenic injection and the secondary lung metastasis from the liver. In addition, TAC-101 inhibited the proliferation of Co-3 (human colon adenocarcinoma) that formed a single nodule in the liver of athymic nude mice by intrahepatic implantation. The growth inhibitory effect of TAC-101 on AZ-521 experimental liver metastasis was observed when treatment was started on day 7, 14, or 21 which may correspond to the progressive stage of liver metastasis in clinical settings. Multiple administration of TAC-101 (8 mg/kg/day) significantly prolonged survival time of the animals with liver met astasis by intrasplenic injection of AZ-521 (T/C = 230%) and A549 (human lung adenocarcinoma; T/C = 186%). These effects of TAC-101 were stronger than those of 5-FU, CDDP or ATRA. Furthermore, TAC-101 inhibited the binding of AP-1 to DNA on electrophoretic mobility shift assay using nuclear extract of AZ-521 cells, although ATRA did not inhibit. These findings suggested that TAC-101 may be a candidate for a new class of anti-cancer agents for liver metastasis. © Rapid Science Ltd.  相似文献   
82.
Oesophageal squamous cell carcinoma with lymphoid stroma   总被引:4,自引:0,他引:4  
Summary We treated a 70-year-old Japanese man with squamous cell carcinoma of the oesophagus with evidence of lymphoid stroma. The tumour consisted of a main lesion invading the muscular layer of the oesophagus, in association with wide areas of carcinoma in situ. The tumour stroma of the lesion was nondesmoplastic and was uniformly infiltrated mainly by abundant lymphocytes and plasma cells. Immunohistochemically, the lymphocytes consisted of a large number of T lymphocytes and a small number of B lymphocytes. S-100 protein positive cells were marked in the tumour cell nests and necrotic change of tumour cells was frequent. Abundant infiltration of lymphocytes and plasma cells was also wide-spread beneath the carcinoma in situ, together with the lymphoid follicles. Carcinoma with lymphoid stroma can occur not only in the breast, uterine cervix, nasopharynx and stomach but also in the oesophagus.  相似文献   
83.
84.
The function of the Fc receptors γ chain (FcRγ) for the expression of the T cell receptor (TCR) complex and for T cell development, especially for T cells localized in epithelia, was investigated by analyzing FcRγ-deficient mice. In wildtype mice, CD8αα+β?TCRαβ+ T cells of intestinal intraepithelial lymphocytes (i-IEL) utilized CD3ζ homodimers and ζ-FcRγ heterodimers, whereas CD8α α+β?TCRγδ+ i-IEL used ζ-FcRγ and FcRγ homodimers in the TCR complex. On the other hand, these T cells in FcRγ-deficient mice contained only ζ homodimers. The surface expression of the TCR complex was reduced in CD8αα+β?i-IEL and dendritic epidermal T cells (DETC) in these mice, whereas the development of these T cells was normal. The degree of reduction appeared to depend on the expression level of FcRγ. In contrast to these populations, TCRγδ+ intraepithelial T cells in reproductive organs (r-IEL) were dramatically decreased, suggesting that the development of r-IEL is FcRγ-dependent, probably due to the predominant usage of FcRγ homodimers in the TCR complex. These results indicate that the FcRγ chain contributes differently to the TCR expression and to the development of T cells localized in epithelia.  相似文献   
85.
This study examined the effects of voluntary abdominal breathing (VAB) on the electroencephalogram (EEG) in 22 healthy subjects. VAB was characterized by prolonged rhythmic contraction of abdominal muscles for 20 min in an eyes-closed condition. The breathing rate was instructed to be very slow, i.e., 3-4 breaths/min (inspiratory time for 6-8s and expiratory time for 9-12s). A low-frequency alpha band appeared immediately after eye closing, but it later disappeared and was replaced by a new development of a high-frequency alpha band 4-5 min after the onset of VAB. The subjects had a feeling of vigor-activity with a tendency of reduced anxiety during and/or after VAB, as assessed by POMS and STAI questionnaire scores. On the other hand, during resting in the eye-closed condition, the disappearance of the low-frequency alpha band was replaced by the occurrence of a theta/delta band. The subjects became drowsy in this condition. We therefore conclude that the increase in high-frequency alpha activity is linked to the state of vigor-activity with a tendency of reduced anxiety. Since the urinary serotonergic level significantly increased after the VAB, we suggest that the serotonergic neurons within the brain may produce the changes in the EEG patterns.  相似文献   
86.
87.
A case of polymorphous low-grade adenocarcinoma (PLGA) in the submandibular gland is reported. A 72 year old woman presented with a 5 year history of a gradually expanding tumor in the submandibular region. The surgical specimen revealed a relatively well demarcated tumor, 35 × 35 × 20 mm in size. Macroscopically, necrosis and hemorrhage were not seen in the solid tumor. Histologically, the tumor growth pattern was variable, composed of tubular, papillary, solid, trabecular and cribriform structures. Immunohistochemically, some tumor cells were positive for epithelial membrane antigen (EMA), S-100 protein, keratin, and carcino-embryonic antigen (CEA). Electron microscopically, prominent microvilli projected into the luminal spaces, and basal lamina and hemidesmosomes were seen in the tumor cells adjacent to the connective tissues. The submandibular gland is an extremely rare location for PLGA. To the authors' knowledge, this is the first case of its kind reported in the English literature.  相似文献   
88.
89.
Histologic transformation in the course of non-Hodgkin's lymphoma (NHL) has been reported to occur in 18 to 30% of the cases. Less favorable prognosis in cases with initial low grade malignancy followed by emergence of high grade malignancy has been previously described. In the previous literature, the histologic transformation has been examined mostly in nodal NHL. In the present study, histologic transformation in the course was investigated on 20 cases with early extranodal NHL. All these 20 cases were diffuse lymphomas, and were composed of 7 cases with low grade malignancy and 13 cases with high grade malignancy. Histologic transformation was not observed in any of these cases. These findings indicate that the frequency of histologic transformation is much lower in extranodal NHL than in nodal NHL. The prognostic significance of these findings is also discussed.  相似文献   
90.
Although injection-site granulomas caused by leuprorelin acetate have been reported, there have been no reports of granulomas caused by both leuprorelin acetate and goserelin acetate. An 81-year-old man presented with subcutaneous nodules of the abdominal wall and upper arm, where 11.25 mg of leuprorelin acetate had been injected for the treatment of prostate cancer. Because of these nodules, treatment was changed to goserelin acetate. Nevertheless, he presented with another subcutaneous nodule at the injection site. Histological examination showed that these nodules consisted of numerous giant cells that were CD3-positive T lymphocytes and CD68-positive histiocytes associated with granulomatous changes. The granulomas had likely been caused by delayed-type hypersensitivity to leuprorelin acetate injection. The granuloma that formed after goserelin acetate injection might thus have developed owing to the immunogenicity of the previous leuprorelin acetate injections. The patient underwent surgical castration. The present case suggests that both leuprorelin acetate and goserelin acetate can cause injection-site disorders.  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