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   9229篇
  免费   883篇
  国内免费   12篇
耳鼻咽喉   43篇
儿科学   225篇
妇产科学   152篇
基础医学   1202篇
口腔科学   190篇
临床医学   1158篇
内科学   1624篇
皮肤病学   120篇
神经病学   665篇
特种医学   424篇
外科学   1095篇
综合类   157篇
一般理论   4篇
预防医学   885篇
眼科学   823篇
药学   863篇
中国医学   8篇
肿瘤学   486篇
  2021年   114篇
  2020年   88篇
  2019年   146篇
  2018年   139篇
  2017年   106篇
  2016年   136篇
  2015年   149篇
  2014年   209篇
  2013年   344篇
  2012年   415篇
  2011年   386篇
  2010年   250篇
  2009年   209篇
  2008年   442篇
  2007年   441篇
  2006年   405篇
  2005年   413篇
  2004年   393篇
  2003年   334篇
  2002年   315篇
  2001年   294篇
  2000年   325篇
  1999年   260篇
  1998年   113篇
  1997年   114篇
  1996年   117篇
  1995年   116篇
  1994年   108篇
  1993年   82篇
  1992年   234篇
  1991年   212篇
  1990年   197篇
  1989年   194篇
  1988年   187篇
  1987年   196篇
  1986年   158篇
  1985年   182篇
  1984年   136篇
  1983年   94篇
  1982年   79篇
  1981年   59篇
  1979年   93篇
  1978年   86篇
  1977年   76篇
  1976年   66篇
  1975年   61篇
  1974年   75篇
  1973年   66篇
  1972年   62篇
  1971年   58篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
A new type of disposable external defibrillation electrode has been developed to reduce the skin irritation commonly associated with defibrillation and synchronised cardioversion. This design employs an impedance gradient to reduce the proportion of current delivered to the electrode periphery. The temperature distribution under the new electrode was compared with that of four other types of commercially available electrodes after repeated high-energy biphasic defibrillation discharges to domestic swine. Skin temperature distributions were acquired using non-invasive thermography. Measurements of the maximum temperature rise at each electrode site, taken 3.6s after the fifth defibrillation discharge, demonstrated that the new impedance-gradient electrode produced 50–60% less skin heating than two of the three uniform-impedance electrode designs. Histological examination of erythematous sites excised 24h after defibrillation quantified the associated skin damage using a scoring protocol developed for this study. In contrast to previous studies, histological examinations demonstrated second-degree skin burns following defibrillation. The new electrode design, however, induced 44–46% less skin damage than two of the traditional uniform-impedance electrodes.  相似文献   
62.
The purpose of this study was to develop an enzyme-linked immunospot assay (ELISpot assay) that can be used with human adherent cells. While standard enzyme-linked immunosorbent assays (ELISAs) are available and widely used and ELISpot assays are used for nonadherent lymphocytes, no ELISpot assay has been developed for adherent cells. We used primary human fibroblasts from four different tissues (myometrium, lung, gingiva, and orbit), either unstimulated or interleukin (IL)-1beta-activated, to evaluate an ELISpot assay. Antibody pairs for IL-6 and IL-8 were used and results were compared to a standard ELISA. We found that we could reliably detect IL-6 and IL-8 spots with as few as 10 fibroblasts. Optimal cell numbers were 50 cells per well incubated for 8 h, although spots appeared as early as 2 h after incubation. Spots were absent when cells, primary, or secondary anti-cytokine antibodies were omitted from the protocol. Spot number and size can be ascertained using current automated ELISpot reader technology. The frequency of IL-6 and IL-8-producing human fibroblasts could also be determined. For example, 60% of the lung fibroblasts express IL-6, but IL-8 can be detected from only 40% of the cells. Approximately 80% of the human orbital fibroblasts make IL-6, whereas approximately 50% generate IL-8 following IL-1beta stimulation. These new findings show that fibroblasts from different human tissues display different frequencies of cytokine production and this further supports the concept of fibroblast diversity. The sensitivity of this new ELISpot assay is adequate for cytokine detection in just a few cells, unlike the standard ELISA. It should permit ascertaining the frequency of fibroblasts and other adherent cells that produce cytokines and, if desired, can be used in tandem with a standard ELISA to determine total cytokine produced. Moreover, the assay is suitable for normal human adherent cells that are often short-lived and difficult to cultivate.  相似文献   
63.
Summary: B cells are unique in that they generate and tolerate a high rate of mutations in their antigen receptor genes and employ these mutations as a basis of avidity maturation. The precise role of the mutational machinery versus subsequent selection in determining the frequency and distribution of mutations has not been fully analyzed. To address these issues, the influence of the intrinsic mutational machinery and subsequent selection on the frequency and distribution of mutations in the expressed human immunoglobulin repertoire was analyzed. Analysis of non-productively rearranged vH genes from individual human B cells provided an opportunity to examine the immediate impact of somatic hypermtitation without superimposed selective influences. Comparison with the frequency and distribution of mutations in the productively rearranged human VH genes permitted an estimate of the influences of subsequent selection.  相似文献   
64.
The usefulness of lysostaphin for the removal of cell-adherent and extracellular bacteria in assays performed to measure the intracellular killing of Straphylococcus aureus by granulocytes was investigated. The results showed that the adherence of lysosiaphin to the granulocyte surface is effectuated by a temperature-independent process and that bound lysostaphin is still microbicidal. Lysosiaphin also penetrates into the granulocytes by a temperature dependent process and kills ingested S. aureus intracellularly. Therefore, despite reports to the contrary in the literature, lysosiaphin is not a reliable agent for the removal of only extracellular S. aureus and should no longer be used in assays to determine the rate of intracellular killing by granulocytes.  相似文献   
65.
Cytomegalovirus reactivation and infection post-allogeneic hematopoietic stem cell transplant continue to cause morbidity and mortality. Current pharmacologic therapies are limited by side effects. Adoptive transfer of ex vivo generated cytomegalovirus-specific T cells has the potential to restore immunity, prevent cytomegalovirus, and circumvent the need for pharmacologic therapies. We have generated donor-derived cytomegalovirus-specific cytotoxic T cells using dendritic cells pulsed with the HLA-A2 restricted nonapeptide NLVPMVATV (NLV) derived from the cytomegalovirus-pp65 protein. These cytotoxic T cells have been given prophylactically to 9 recipients aged 4 to 65 years on or after day 28 post-allogeneic hematopoietic stem cell transplant. Only 2 of 9 recipients received T cell depletion in vivo or in vitro. There were no immediate adverse reactions to the infusions. During 97-798 days of follow-up, 2 recipients developed cytomegalovirus reactivation; neither developed cytomegalovirus disease or required pharmacotherapy. Three recipients developed acute graft versus host disease after infusion. Two recipients died, 1 from thrombotic thrombocytopenia purpura secondary to cyclosporine, 1 from complications of graft versus host disease. A transient increase in numbers of cytomegalovirus-specific T cells demonstrated by NLV-tetramer binding was seen in 6 recipients. Prophylactic adoptive transfer of NLV-specific T cells is safe and may be effective in preventing cytomegalovirus reactivation.  相似文献   
66.
Monoclonal antibody LICR-LON-M18 is a marker of normal human breast epithelial cell differentiation. The epitope recognized by LICR-LON-M18 is a prominent component of luminal plasma membranes of nonneoplastic resting and lactating human breast epithelial cells but is rarely expressed by human breast carcinomas. With the use of competitive binding-inhibition studies, the immunodominant portion of the LICR-LON-M18 epitope was shown to be the following oligosaccharide sequence [with galactose (Gal) and N-acetylglucosamine (GlcNAc)]: Gal beta 1----4GlcNAc beta 1----. This structure was distinct from Gal beta 1----3GalNac, which was bound by peanut agglutinin (PNA) and was not recognized by LICR-LON-M18 [corrected]. With the use of biochemical techniques, the present data not only confirmed sialylation and consequent "masking" of the LICR-LON-M18 epitope and PNA determinants in human breast carcinomas but also identified the particular groups of glycoproteins involved in this process. These studies provided additional support for the thesis that sialylation of human breast carcinoma glycoproteins represented an enhancement of specific differentiation events normally regulated in the morphogenesis of nonneoplastic human breast epithelium and that specific glycoproteins became masked during the genesis of primary human breast cancer.  相似文献   
67.
Conventional management of acute left sided colonic obstruction employs some form of proximal colostomy. Intraoperative antegrade colonic irrigation relieves proximal faecal loading and may permit safer primary resection and anastomosis. The results of a pilot study are presented, and are shown to be favourable.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.4M), or click on a page image below to browse page by page.
 5657 

Images in this article

Figure 1.
on p.56
Click on the image to see a larger version.
  相似文献   
68.
69.
Radiation-induced breast angiosarcoma, or secondary angiosarcoma (SAS), is a rare entity with a high risk of metastatic recurrence. Herein, we describe the use of intraoperative fluorescence-based skin angiography to guide surgical resection following a novel immunotherapy-based regimen for SAS resulting in a complete pathological response.  相似文献   
70.
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