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   18389篇
  免费   1370篇
  国内免费   51篇
耳鼻咽喉   102篇
儿科学   564篇
妇产科学   531篇
基础医学   2506篇
口腔科学   323篇
临床医学   2598篇
内科学   3361篇
皮肤病学   385篇
神经病学   1826篇
特种医学   350篇
外科学   1611篇
综合类   176篇
一般理论   38篇
预防医学   2371篇
眼科学   429篇
药学   1352篇
  3篇
中国医学   43篇
肿瘤学   1241篇
  2024年   92篇
  2023年   244篇
  2022年   335篇
  2021年   694篇
  2020年   452篇
  2019年   628篇
  2018年   671篇
  2017年   495篇
  2016年   552篇
  2015年   572篇
  2014年   744篇
  2013年   1055篇
  2012年   1493篇
  2011年   1472篇
  2010年   829篇
  2009年   675篇
  2008年   1130篇
  2007年   1156篇
  2006年   1057篇
  2005年   1050篇
  2004年   922篇
  2003年   878篇
  2002年   733篇
  2001年   103篇
  2000年   72篇
  1999年   95篇
  1998年   145篇
  1997年   125篇
  1996年   111篇
  1995年   95篇
  1994年   83篇
  1993年   94篇
  1992年   54篇
  1991年   49篇
  1990年   39篇
  1989年   30篇
  1988年   41篇
  1987年   41篇
  1986年   34篇
  1985年   37篇
  1984年   46篇
  1983年   44篇
  1982年   48篇
  1981年   45篇
  1980年   53篇
  1979年   22篇
  1978年   32篇
  1977年   29篇
  1974年   20篇
  1973年   23篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Berger AC  Watson JC  Ross EA  Zalatoris A  Hoffman JP 《The American surgeon》2004,70(2):169-73; discussion 173-4
Increased expression of vascular endothelial growth factor (VEGF) by pancreatic cancer correlates with poor survival. The significance of VEGF in biliary and pancreatic secretions in periampullary cancers is unknown. Bile and pancreatic juice samples were collected from patients undergoing pancreaticoduodenectomy (PD). All samples were frozen at -70 degrees C until subsequent analysis for VEGF concentration using enzyme-linked immunoabsorbent assay (ELISA). Plasma VEGF levels in pancreatic cancer patients were <10 pg/mL. The biliary VEGF concentration for patients with malignancy was significantly elevated compared to benign disease (P = 0.05). There was no difference in pancreatic VEGF concentrations between benign and malignant disease. Cancer patients undergoing preoperative chemoradiation (CRT) had lower biliary and pancreatic VEGF concentrations than those who did not. Preoperative biliary drainage (BD) was associated with decreased VEGF concentrations in bile (3500 pg/mL vs 7740 pg/mL, P = 0.027). Patients undergoing both CRT and BD had diminished biliary and pancreatic VEGF concentrations compared to those who had neither. This was statistically significant for pancreatic VEGF concentrations (917 pg/mL vs 4723 pg/mL, P = 0.044). VEGF is highly concentrated in bile and pancreatic juice compared to plasma. Preoperative CRT and BD significantly reduce these levels in patients with periampullary cancers. Antiangiogenic therapy aimed at interrupting the VEGF pathway appears to be a logical target in periampullary cancer.  相似文献   
82.
End-stage renal disease (ESRD) under hemodialyses (HD) is related with a higher propensity to infections, essentially due to T-cell lymphopenia. We postulated that HD procedure affects CD4(+) T cells, especially by inducing apoptotic death and that recombinant human erythropoietin (rhEPO) therapy may also play an important role in the modulation of the immune system in these patients. T-cell phenotype and apoptosis of HD patients and healthy controls were evaluated by flow cytometry using anticoagulated whole-blood samples. In 12 HD patients, these parameters were also analyzed before and immediately after HD procedure. HD patients showed a decrease in total circulating CD3(+) lymphocytes, especially in CD4(+) T cells (0.747 ± 0.410 vs. 0.941 ± 0.216 × 10(9)/L, p < 0.05), which could be a consequence of the higher proportion of CD3(+) and CD4(+) lymphocytes in the latest stage of apoptosis (or death) and of the higher proportion of apoptotic CD4(+) T cells observed in the patients immediately after HD procedure (2.91 ± 0.780 vs. 3.90 ± 1.96, p < 0.05). A positive and statistically significant correlation between CD3(+) and CD4(+) lymphocytes in latest stage of apoptosis (or death) with HD time was found (CD3(+): r = 0.592, p < 0.01; CD4(+): r = 0.501, p < 0.01). We also found a negative and significant correlation between weekly rhEPO doses and the number of CD4(+) T cells (r = -0.358, p < 0.05). In conclusion, HD procedure still contributes to the development of T-cell lymphopenia, at least in part, by apoptosis induction. It was also shown that rhEPO therapy is associated with the CD4(+) T-cell decline, possibly by immune modulation, eliminating atypical cells and helping to restore the CD4(+) T-cell subset.  相似文献   
83.
Approximately 25 % of mismatch repair (MMR) variants are exonic nucleotide substitutions. Some result in the substitution of one amino acid for another in the protein sequence, so-called missense variants, while others are silent. The interpretation of the effect of missense and silent variants as deleterious or neutral is challenging. Pre-symptomatic testing for clinical use is not recommended for relatives of individuals with variants classified as ‘of uncertain significance’. These relatives, including non-carriers, are considered at high-risk as long as the contribution of the variant to disease causation cannot be determined. This results in continuing anxiety, and the application of potentially unnecessary screening and prophylactic interventions. We encountered a large Irish Lynch syndrome kindred that carries the c.544A>G (p.Arg182Gly) alteration in the MLH1 gene and we undertook to study the variant. The clinical significance of the variant remains unresolved in the literature. Data are presented on cancer incidence within five kindreds with the same germline missense variant in the MLH1 MMR gene. Extensive testing of relevant family members in one kindred, a review of the literature, review of online MMR mutation databases and use of in silico phenotype prediction tools were undertaken to study the significance of this variant. Clinical, histological, immunohistochemical and molecular evidence from these families and other independent clinical and scientific evidence indicates that the MLH1 p.Arg182Gly (c.544A>G) change causes Lynch syndrome and supports reclassification of the variant as pathogenic.  相似文献   
84.
Ovarian cancer is an important health concern worldwide. The majority of patients present with advanced disease, and despite initial chemosensitivity, most relapse and die from their disease. Better therapeutic options are urgently required. Maximal surgical debulking in combination with platinum/taxane chemotherapy has been the standard of care in advanced ovarian cancer since the mid-1990s. Trials investigating the addition of a third chemotherapeutic agent have disappointingly failed to demonstrate benefit. Intra-peritoneal therapy demonstrated improvements in outcomes in some trials, but at the cost of increased toxicity and inconvenience. Encouragingly, prospective data has now demonstrated benefits with bevacizumab in both the first-line and relapsed settings; however, interpretation is complex, particularly considering recent data demonstrating non-inferiority of neo-adjuvant chemotherapy with delayed primary surgery, and other data demonstrating a substantial improvement in outcome as a result of first-line paclitaxel dose fractionation. This article reviews the recent advances in ovarian cancer treatment and discusses current management and key areas for future research.  相似文献   
85.
86.
87.
88.
I conducted a longitudinal phenomenological study in England to explore the perceptions of 10 lactating women related to the nature of their breast milk and their ability to exclusively breast-feed their babies. The women viewed breast-feeding as a mechanical manufacturing process, and they carefully monitored the output of breast milk. Health care professionals contributed to the women's perceptions and displayed mechanistic assumptions in relation to breastfeeding, reflecting their enculturation through the biomedical paradigm. I present personal accounts to highlight the influence of two dominant Western ideologies--biomedical science and capitalism--upon women's perceptions of their breast milk.  相似文献   
89.
90.
In part 1, published last month, causes and clinical features of congestive heart failure in infancy were discussed, and some of the more common malformations were illustrated. In this portion, principles of management and recommendations for specific therapy are presented. Particularly emphasized is digitalization, the most important step in treating the infant with heart failure.  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