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   22426篇
  免费   1449篇
  国内免费   923篇
耳鼻咽喉   109篇
儿科学   255篇
妇产科学   297篇
基础医学   4860篇
口腔科学   287篇
临床医学   2183篇
内科学   3986篇
皮肤病学   427篇
神经病学   494篇
特种医学   394篇
外国民族医学   9篇
外科学   2536篇
综合类   3440篇
现状与发展   8篇
预防医学   1165篇
眼科学   166篇
药学   1121篇
  2篇
中国医学   214篇
肿瘤学   2845篇
  2024年   25篇
  2023年   297篇
  2022年   490篇
  2021年   721篇
  2020年   568篇
  2019年   560篇
  2018年   590篇
  2017年   562篇
  2016年   570篇
  2015年   633篇
  2014年   1027篇
  2013年   1105篇
  2012年   952篇
  2011年   1208篇
  2010年   977篇
  2009年   998篇
  2008年   1055篇
  2007年   1203篇
  2006年   1084篇
  2005年   1062篇
  2004年   910篇
  2003年   790篇
  2002年   840篇
  2001年   743篇
  2000年   645篇
  1999年   576篇
  1998年   542篇
  1997年   515篇
  1996年   437篇
  1995年   338篇
  1994年   380篇
  1993年   331篇
  1992年   259篇
  1991年   221篇
  1990年   262篇
  1989年   165篇
  1988年   161篇
  1987年   119篇
  1986年   105篇
  1985年   182篇
  1984年   132篇
  1983年   91篇
  1982年   84篇
  1981年   75篇
  1980年   60篇
  1979年   49篇
  1978年   35篇
  1977年   23篇
  1976年   23篇
  1974年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Introduction:Prostate-specific antigen (PSA) kinetic patterns during neoadjuvant androgen deprivation therapy have been shown to predict unfavorable long-term outcomes.Objective:To investigate the effect of testosterone escape (TE) on these kinetic patterns, as this had not been previously reported.Methods:There were 50 consecutive prostate cancer patients who received 6 months of triptorelin prior to definitive radiotherapy (RT). Testosterone and PSA levels were measured at baseline and every 6 weeks. Clinical factors were tested for their ability to predict for TE and unfavorable PSA kinetic patterns. The effects of TE, at both 1.7 and 0.7 nmol/L levels, were analyzed.Results:TE occurred in at least one reading for 14% and 34% of the patients at the 1.7 and 0.7 nmol/L levels, respectively. No baseline factors predicted TE. The median PSA halving time was 25 days and the median pre-RT PSA level was 0.55 ng/mL. The only factor significantly associated with a higher pre-RT PSA level was a higher baseline PSA level. The only factor that significantly predicted a longer PSA halving time was TE at the 1.7 nmol/L level.Conclusions:TE and higher baseline PSA levels may adversely affect PSA kinetics and other outcomes for patients undergoing neoadjuvant hormone therapy prior to radiotherapy. Studies investigating the tailoring of neoadjuvant therapy by extending the duration in those patients with a higher baseline PSA level or by the addition of anti-androgens in those demonstrating TE, should be considered.  相似文献   
103.
人子宫内膜抗原的纯化与鉴定   总被引:3,自引:0,他引:3  
  相似文献   
104.
We have prepared 2 mouse monoclonal antibodies which react with differentiation antigens on guinea pig lymphoid cells. Monoclone 5AB2 recognizes an antigen expressed on both T and B lymphocytes and absent on macrophages. It has proven useful in the preparation of populations of antigen presenting cells which are free of T and B lymphocytes. The second monoclonal, 8BE6, is specific for peripheral T cells and 10% of thymocytes. It reacts with a 68,000 dalton molecule which is also expressed on the guinea pig B cell leukemia, EN-L2C. 8BE6 has proven to be lytic for peripheral T cells in the presence of rabbit complement and has been used to deplete T cells from heterogenous cell populations.  相似文献   
105.
Ia antigens were shown to be present in the cell almost exclusively as mature alpha beta dimers which split into separate alpha and beta chains after boiling in SDS. In contrast metabolically labelling the cells with [35S]methionine resulted in only free alpha and beta chains being labelled. It is concluded that this widely used type of labelling, although useful for studying intermediate synthesis, should not be used for labelling mature cell surface molecules.  相似文献   
106.
107.
鼻咽癌癌细胞群体的PCNA免疫组化研究   总被引:6,自引:2,他引:6  
应用免疫组化技术对47例石蜡包埋组织的鼻咽癌癌细胞群体的增殖细胞核抗原(PCNA)进行分析。结果显示:角化性癌细胞和梭形癌细胞、不规则形癌细胞至泡状核癌细胞群体,其PCNA阳性率依次递增,表明鼻咽癌存在增殖潜能异质性的癌细胞群体,泡状核癌细胞增殖能力最高,不规则形癌细胞次之。作者认为不同形态的癌细胞群体在组织中的比例不但决定鼻咽癌的组织类型,而且其增殖潜能异质性将影响鼻咽癌治疗和临床预后。  相似文献   
108.
We examined the effect of endobronchial (EB) or whole-lung (WL) challenge with ragweed or Timothy grass extract on alveolar macrophage (AM) activation. Expression of 17 constitutive activation markers on AM was examined by flow cytometry. Late-phase bronchial obstruction was greater after WL challenge, while changes in bronchoalveolar lavage cytology (eosinophil accumulation) were greater after EB challenge. After EB challenge, levels of 10 of 17 markers (CD11a, CD11b, CD14, CD18, CD23, CD32, CD63, CD64, HLA-class I, and HLA-DR) were significantly increased (by 33-234%, P < 0.05). Six markers (CD16, CD29, CD33, CD35, CD44, CD71, and HLA-DQ) remained unchanged. Levels of seven markers following EB challenge (CD14, CD16, CD18, CD29, CD32, HLA-class I, and HLA DQ) correlated with airway sensitivity to methacholine. WL challenge only increased expression of HLA-class I. The different results obtained with the two challenge methods probably depend on higher local concentrations of allergen in the EB challenge. We suggest that activation of AM occurs following EB challenge with antigen in asthmatics.  相似文献   
109.
ABSTRACT: Efforts were made to disrupt and solubilize human sperm cells and to evaluate the product for its content of infertility antibody-related antigens. In the procedure that was developed, a well-washed sperm sample is treated with 0.1 M dithiothreitol for 60 min, followed by trypsin at 0.1 mg/ml for 30 min, and then by soybean trypsin inhibitor. A mixture of DNAses I and II are added. After centrifuging, the resuspended pellet (RP) and the final supernatant (FS) show several degrees of cellular breakdown. Immunological evaluation was done with a strongly positive human serum containing sperm-head antibody. From the inhibition of sperm agglutination, we could conclude that the desired soluble antigen was obtained in the FS fraction.  相似文献   
110.
Timely and rapid diagnosis of cytomegalovirus (CMV) infection is important for the management of transplant patients. We compared three serological assays, IgM immunoblot and IgG/IgM enzyme immunoassay (EIA), as well as the detection of CMV antigens in polymorphonuclear blood leukocytes (antigenemia), for their value in the early diagnosis of CMV infection. Thirty-one patients were monitored longitudinally for 3 months after renal transplantation. Laboratory documented CMV infection occurred in 20 patients. All of these cases showed a positive IgM immunoblot result that was confirmed by at least one of the other test assays (IgG EIA 19/20, antigenemia assay 13/20, and IgM EIA 12/20). All of the ten patients whose clinical picture was compatible with symptomatic CMV disease were positive for CMV infection according to IgM immunoblot and IgG EIA, nine were positive according to the antigenemia assay, and seven were positive according to IgM EIA. With reference to the temporal pattern, the antigenemia assay indicated CMV infection significantly earlier than the serological tests (P0.05). In symptomatic patients CMV antigen-positive leukocytes were, on the average, detected on the day of onset of symptoms, whereas detection by IgM immunoblot, IgG EIA, and IgM EIA followed 8, 13, and 14 days later, respectively. These results show that: (1) the CMV antigenemia assay is very useful for the early diagnosis of symptomatic CMV infections; (2) CMV antibodies, as an indicator of CMV infection, are detectable earlier and more frequently by IgM immunoblot than by IgG/IgM EIA; (3) compared to CMV anti-genemia, the IgM immunoblot indicated CMV infection more often but significantly later; and (4) only a combination of several diagnostic methods allows optimal detection of CMV infections in renal transplant patients.  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