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   1494篇
  免费   126篇
  国内免费   1篇
耳鼻咽喉   3篇
儿科学   33篇
妇产科学   31篇
基础医学   175篇
口腔科学   71篇
临床医学   227篇
内科学   271篇
皮肤病学   40篇
神经病学   70篇
特种医学   113篇
外国民族医学   1篇
外科学   206篇
综合类   45篇
预防医学   110篇
眼科学   9篇
药学   140篇
中国医学   1篇
肿瘤学   75篇
  2022年   20篇
  2021年   30篇
  2020年   23篇
  2019年   27篇
  2018年   36篇
  2017年   19篇
  2016年   21篇
  2015年   26篇
  2014年   32篇
  2013年   47篇
  2012年   35篇
  2011年   46篇
  2010年   62篇
  2009年   66篇
  2008年   55篇
  2007年   40篇
  2006年   55篇
  2005年   41篇
  2004年   31篇
  2003年   45篇
  2002年   34篇
  2001年   30篇
  2000年   31篇
  1999年   34篇
  1998年   33篇
  1997年   18篇
  1996年   30篇
  1995年   22篇
  1994年   29篇
  1993年   36篇
  1992年   34篇
  1991年   33篇
  1990年   27篇
  1989年   38篇
  1988年   44篇
  1987年   27篇
  1986年   25篇
  1985年   36篇
  1984年   15篇
  1983年   16篇
  1982年   17篇
  1981年   16篇
  1980年   21篇
  1979年   29篇
  1978年   13篇
  1977年   14篇
  1976年   12篇
  1975年   12篇
  1974年   11篇
  1957年   12篇
排序方式: 共有1621条查询结果,搜索用时 15 毫秒
101.
102.
Hepatocyte growth factor/scatter factor (HGF/SF), a cytokine associated with cancer cell migration and invasion, is synthesised as pro-HGF/SF and requires activation by factors such as the HGF activator (HGFA). The present study examined the expression of HGF/SF, HGFA, the two inhibitors to HGFA action known as hepatocyte growth factor activator inhibitors type 1 and 2 (HAI-1 and HAI-2), and the HGF/SF receptor, c-Met. We examined a variety of normal and cancer cells, which included breast, prostate, colon, bladder, liver, lung, and pancreatic cancer cell lines. The cell lines all displayed different patterns of expression, and in some of the cancer cell lines the concomitant expression of the HGF/SF, c-Met, HGFA and HAI genes was observed. The only cell line to produce a significant amount of HGF/SF was the human fibroblasts (MRC-5) which also co-expressed the c-Met and HGFA genes to allow autocrine regulation of HGF/SF stimulation, and importantly displayed little or no inhibitor presence to suppress the biological function of HGF/SF. The highly invasive breast cancer cells (MDA MB-231) expressed large amounts of both c-Met and HGFA, to enable maximum influence from HGF/SF and did not express the HAI-1 gene at all, which suggests a shift in the activation-inhibition balance to enhance metastatic potential. In contrast, the breast cancer cells of low invasive nature (MCF-7) displayed a low level of c-Met and HGFA expression, while expressing the HAI genes to a high degree. However, there was no correlation between HAI-1 and HAI-2 expression. Interestingly, there appeared to be an inverse correlation between the degree of HGFA and HAI-1 expression, which may influence the metastatic ability of the cancer cells. This study has shown that c-Met, HGF/SF and its activator and inhibitors are expressed in different patterns in cancer cells and in normal cells. The balance between HGF/SF activation and HGFA inhibition is critical to the metastatic potential of the tumour cells, and the invasive nature of the cancer cell lines correlated to the degree of c-Met and/or HGFA presence along with HAI-1 expression.  相似文献   
103.
BACKGROUND: Early onset idiopathic generalised dystonia is a progressive and profoundly disabling condition. Medical treatment may ameliorate symptoms. However, many children have profound, intractable disability including the loss of ambulation and speech, and difficulties with feeding. Following the failure of medical management, deep brain stimulation (DBS) of the globus pallidus internus (GPi) has emerged as an alternative treatment for the disorder. METHODS: We describe four children who presented with dystonia. RESULTS: Following the failure of a range of medical therapies, DBS systems were implanted in the GPi in an attempt to ameliorate the children's disabilities. All children found dystonic movements to be less disabling following surgery. Compared with preoperative Burke, Fahn and Marsden Dystonia Rating Scale scores, postoperative scores at 6 months were improved. CONCLUSIONS: DBS is effective in improving symptoms and function in children with idiopathic dystonia refractory to medical treatment. Whilst surgery is complex and can be associated with intraoperative and postoperative complications, this intervention should be considered following the failure of medical therapy.  相似文献   
104.
The influence of N -ethyl- and N -benzyl-1,2-diphenyl ethanolamines (compounds E and B, respectively) was examined on the spontaneously contracting rabbit jejunum and the rat uterus together with their influence on the contractions induced by some spasmogens in the guinea-pig ileum and oxytocics and CaCl2in the pregnant rat uterus. Both E and B inhibited the spontaneous contractions of the rabbit jejunum with ID50values of 0.13 and 0.03 μmol ml−1. Their inhibitory activities were not antagonized by α- or β-adrenoceptor blockers but significantly reversed by CaCl2(0.015 μmol ml−1). The compounds also antagonized nicotine, ACh-, histamine-, 5-HT- and CaCl2-induced contractions by 44–100%. Compound E seemed to be several times more potent than B in inhibiting the spontaneous uterine contractions with an ID50of (7 nmol ml−1). Their inhibitory effects were not antagonized by β2-adrenoceptor or H2-receptor blocking drugs. Both compounds (40 nmol ml−1) antagonized in a competitive manner CaCl2-induced contractions in the K+-depolarised uterus and PGE2and oxytocin-induced uterine contractions. The ID50values were in the range of 1.6–10.7 nmol ml−1. The results suggest that E and B compounds may be considered as putative L-Ca2+channel blockers with certain selectivities. The E compound seemed to be more selective against uterine L-Ca2+channels and the B compound against intestinal smooth muscles. Thus, the compounds may be of potential value in treatment of some colics, the irritant bowel syndrome, dysmenorrhoea and premature deliveries. 1999 Academic Press@p$hr  相似文献   
105.
Mediastinal masses: alternative approaches to CT-guided needle biopsy   总被引:10,自引:1,他引:10  
Bressler  EL; Kirkham  JA 《Radiology》1994,191(2):391
  相似文献   
106.
The nuclear medicine bleeding scan is frequently insufficient to locate sites of bleeding precisely, in spite of its great sensitivity. A small, hand-held Geiger-Müller counter, placed directly on exposed intestine in the operating room, enables precise location of the probable bleeding site. In three patients, the technique allowed a minimal amount of intestine to be resected, distinguished between large- and small-intestinal hemorrhage, and eliminated other foci as sites of bleeding.  相似文献   
107.
Tumor cells from eight adult patients with T-cell chronic malignancies were investigated with a series of monoclonal antibodies recognizing T- cell differentiation antigens. This series allowed definition of discrete subpopulations of mature T cells with functional specialization. All six patients with Sezary syndrome and one patient with T-chronic lymphocytic leukemia had cells with the same phenotype as normal helper/inducer T cells, whereas the other patient with T- chronic lymphocytic leukemia had cell with the same phenotype as normal cytotoxic/suppressor T cells. Some clinical manifestations observed in these patients may reflect retention of functional activities by their malignant cells.  相似文献   
108.
109.
110.
Intralesional (IL) vitamin D3 is an emerging treatment for cutaneous warts. However, its effectiveness and exact mechanism is not fully evaluated. We aimed to compare the efficacy and safety of IL purified protein derivative (PPD) and IL vitamin D3 in multiple warts and to investigate their systemic effect clinically and immunologically. Forty‐five patients with multiple extragenital warts were treated with IL‐PPD (22 patients) or IL vitamin D3 injection (23 patients) for a maximum of three sessions at 3 week intervals. Decrease in size and number of warts and adverse effects were evaluated. Serum interleukin‐12 (IL‐12) and interferon‐gamma (IFN‐γ) levels were measured before and 3 weeks after the last session. Higher clearance rates for all warts were observed with IL‐PPD compared to IL vitamin D (59.1% vs. 21.7% complete clearance, p < .001). Significant increase was found in both serum IL‐12 and IFN‐γ after PPD treatment (p = .034 and p = .04, respectively), but only IFN‐γ after vitamin D3 treatment (p = 0.02). Both IL vitamin D3 and PPD showed positive results in treatment of multiple warts. However, PPD showed higher clinical efficacy and more increase in both IL‐12 and IFN‐γ levels.  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