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   1044篇
  免费   81篇
  国内免费   5篇
耳鼻咽喉   1篇
儿科学   28篇
妇产科学   27篇
基础医学   137篇
口腔科学   31篇
临床医学   94篇
内科学   173篇
皮肤病学   23篇
神经病学   95篇
特种医学   107篇
外科学   146篇
综合类   56篇
预防医学   93篇
眼科学   13篇
药学   37篇
肿瘤学   69篇
  2022年   7篇
  2021年   14篇
  2020年   7篇
  2019年   7篇
  2018年   20篇
  2017年   12篇
  2016年   8篇
  2015年   12篇
  2014年   22篇
  2013年   37篇
  2012年   23篇
  2011年   37篇
  2010年   37篇
  2009年   30篇
  2008年   27篇
  2007年   42篇
  2006年   51篇
  2005年   36篇
  2004年   65篇
  2003年   43篇
  2002年   40篇
  2001年   22篇
  2000年   28篇
  1999年   34篇
  1998年   30篇
  1997年   33篇
  1996年   25篇
  1995年   35篇
  1994年   21篇
  1993年   10篇
  1992年   18篇
  1991年   14篇
  1990年   18篇
  1989年   27篇
  1988年   28篇
  1987年   20篇
  1986年   24篇
  1985年   16篇
  1984年   16篇
  1983年   20篇
  1982年   10篇
  1981年   10篇
  1980年   14篇
  1979年   11篇
  1978年   16篇
  1977年   8篇
  1976年   6篇
  1974年   5篇
  1971年   6篇
  1968年   4篇
排序方式: 共有1130条查询结果,搜索用时 55 毫秒
31.
32.
Graphical abstract summarizing the overall results of our study comparing reintervention for a main or central branch pulmonary artery reconstruction site and various patch materials. Autologous pericardium was associate with the lowest reintervention and was free. Multivariable analysis demonstrated lack of superiority of homograft branch patch, which clearly has a much higher cost.
  相似文献   
33.
AIDS and Behavior - The timeline followback (TLFB) takes more resources to collect than the Alcohol Use Disorder Identification Test (AUDIT-C). We assessed agreement of TLFB and AUDIT-C with the...  相似文献   
34.
To test the hypothesis that the Duffy blood group negative genotype is a factor in resistance to Plasmodium vivax, we determined the Duffy blood group, the malaria antibodies, and the slide-demonstrated infection rates with P. vivax and P. falciparum of 420 persons living in Nueva Armenia, Honduras. In all, 247 persons were Duffy negative. Demonstrated infections with P. falciparum were almost equally distributed between Duffy-positive (5,8%) and Duffy-negative (4.9%) persons. Similarly, Duffy-positive (25.6%) and Duffy-negative (28.2%) persons had equal proportions of indirect fluorescent antibody test titers suggestive of past or present P. falciparum infection. In contrast, all 14 P. vivax infections were found in Duffy-negative persons. There was no evidence suggesting that Duffy-positive and Duffy-negative persons had different exposures to malaria. The Duffy negative genotype FyFy appears to be a factor in resistance to P. vivax.  相似文献   
35.
36.
Background The study was performed with an aim to map the pattern of metastasis of squamous cell carcinomas of buccal mucosa to various cervical lymph node levels and analyze its correlation with primary tumor size and histo-pathological grading. Material and Methods 254 patients with squamous cell carcinoma of the buccal mucosa treated with surgery first approach were analyzed retrospectively. The tumor size was noted from pre-operative CT Scans and were divided into early and advanced tumors. The resected specimen was studied to note the histo-pathological grading of the squamous cell carcinoma and the metastatic deposits at various lymph node levels. Results Out of 254 patients (149 females, 105 males), 145 patients showed histo-pathologically proven metastatic deposits in one or more lymph nodes out of which there were 56 patients showing occult metastasis. 78/145 patients showed metastatic involvement of level IB and/or IA lymph nodes, 31 showed involvement of level II and/or I lymph nodes, 27 showed involvement of level III with or without involvement of level I and II and 9 showed metastasis to level IV and V lymph nodes with or without level I, II or III lymph nodes. Cervical lymph node metastasis had statistically significant association with tumor size with advanced tumors showing worse pattern of metastatic spread beyond level I and II lymph nodes. As the degree of differentiation of squamous cell carcinoma reduced, they were more prone for cervical metastasis with moderately and poorly differentiated squamous cell carcinoma showing higher involvement of level III, IV and V lymph nodes. Conclusions The majority of buccal mucosa cases showed metastasis to level I, II and III lymph nodes out of which level IB and/or IA was most frequently involved. Metastasis to level IV and V lymph nodes was rare and was seen especially in patients with advanced primary tumor and poor histo-pathologic differentiation. Key words:Oral squamous cell carcinoma (OSCC), cervical lymph node metastasis, histologic differentiation, locally advanced disease.  相似文献   
37.
Cell nuclear estrogen receptors and cytosol progestin receptors were measured in the pituitary gland, preoptic area and hypothalamus throughout the estrous cycle of the rat. Cell nuclear estrogen receptor levels paralleled changes in serum estradiol concentrations with highest values on proestrus and lowest on diestrus. Proestrous values were 50-60% of capacity for each tissue. Cytosol progestin receptor number in these tissues was also highest on proestrus and lowest on diestrus. With these data as a guide, Silastic capsules filled with estradiol-cholesterol mixtures were used to generate physiologic levels of estrogen receptor occupation within the brain-pituitary complex of ovariectomized rats and to examine the kinetics of estradiol stimulation of lordosis behavior and cyclic gonadotropin release. Our results indicate that the effectiveness of an estradiol stimulus to elicit lordosis or luteinizing hormone release depends on at least three factors: the magnitude of the increment in serum estradiol and brain and pituitary cell nuclear estradiol receptor levels; the duration over which these increments area maintained; and the interval from previous exposure to estrogen.  相似文献   
38.
Eosinophils stimulate fibroblast DNA synthesis   总被引:9,自引:0,他引:9  
Pincus  SH; Ramesh  KS; Wyler  DJ 《Blood》1987,70(2):572-574
Fibrosis complicates a number of chronic inflammatory diseases and occurs in some conditions following chronic hypereosinophilic syndromes. We assessed whether eosinophils might be a source of fibrogenic factors. Extracts of human and guinea pig cell populations enriched for eosinophils contained substances that stimulated tritiated thymidine incorporation by human fibroblasts. Supernatants derived from resting eosinophils and extracts prepared from eosinophil granules also contained fibrogenic factors. Our findings demonstrate a new potential role for eosinophils and suggest a causal relationship between tissue eosinophilia and scar formation in certain parasitic conditions.  相似文献   
39.
Akagawa  KS; Takasuka  N; Nozaki  Y; Komuro  I; Azuma  M; Ueda  M; Naito  M; Takahashi  K 《Blood》1996,88(10):4029-4039
We previously showed that granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF) stimulate the differentiation of human monocytes into two phenotypically distinct types of macrophages. However, in vivo, not only CSF but also many other cytokines are produced under various conditions. Those cytokines may modulate the differentiation of monocytes by CSFs. In the present study, we showed that CD14+ adherent human monocytes can differentiate into CD1+relB+ dendritic cells (DC) by the combination of GM-CSF plus interleukin-4 (IL-4) and that they differentiate into tartrate-resistant acid phosphatase (TRAP)-positive osteoclast-like multinucleated giant cells (MGC) by the combination of M-CSF plus IL-4. However, the monocyte-derived DC were not terminally differentiated cells; they could still convert to macrophages in response to M-CSF. Tumor necrosis factor-alpha (TNF-alpha) stimulated the terminal differentiation of the DC by downregulating the expression of the M-CSF receptor, cfms mRNA, and aborting the potential to convert to macrophages. In contrast to IL-4, interferon-gamma (IFN-gamma) had no demonstrable effect on the differentiation of monocytes. Rather, IFN- gamma antagonized the effect of IL-4 and suppressed the DC and MGC formation induced by GM-CSF + IL-4 and M-CSF + IL-4, respectively. Taken together, these results provide a new aspect to our knowledge of monocyte differentiation and provide evidence that human monocytes are flexible in their differentiation potential and are precursors not only of macrophages but also of CD1+relB+DC and TRAP-positive MGC. Such a diverse pathway of monocyte differentiation may constitute one of the basic mechanisms of immune regulation.  相似文献   
40.
Glioblastoma muhiforme (GBM) is a highly invasive brain tumour that is unvaryingly fatal in humans clesplte even aggres- sive therapeutic approaches such as surgical resection followed by chemotherapy and radiotherapy. Unconventional treatment options such as gene therapy provide an intriguing option for curbing glioma related deaths. To date, gene therapy has yielded encouraging results in preclinical animal models as well as promising safety profiles in phase I clinical trials, but has failed to demonstrate significant therapeutic efficacy in phase III clinical trials. The most widely studied antiglioma gene therapy strategies are suicide gene therapy, genetic immuno- therapy and oncolytic virotherapy, and we have attributed the challenging transition of these modalities into the clinic to four major road- blocks : ( 1 ) anatomical features of the central nervous system, (2) the host immune system, (3) heterogeneity and invasiveness of GBM and (4) limitations in current GBM animal models. In this review, we discuss possible ways to jump these hurdles and develop new gene therapies that may be used alone or in synergy with other modalities to provide a powerful treatment option for patients with GBM.  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