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   2953篇
  免费   369篇
  国内免费   349篇
  2024年   7篇
  2023年   37篇
  2022年   60篇
  2021年   133篇
  2020年   97篇
  2019年   136篇
  2018年   135篇
  2017年   112篇
  2016年   130篇
  2015年   195篇
  2014年   190篇
  2013年   237篇
  2012年   237篇
  2011年   262篇
  2010年   173篇
  2009年   158篇
  2008年   165篇
  2007年   163篇
  2006年   148篇
  2005年   107篇
  2004年   144篇
  2003年   149篇
  2002年   136篇
  2001年   81篇
  2000年   60篇
  1999年   49篇
  1998年   47篇
  1997年   23篇
  1996年   10篇
  1995年   14篇
  1994年   10篇
  1993年   7篇
  1992年   7篇
  1991年   6篇
  1990年   4篇
  1989年   9篇
  1988年   9篇
  1987年   4篇
  1986年   5篇
  1985年   4篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1972年   1篇
  1971年   1篇
  1970年   1篇
排序方式: 共有3671条查询结果,搜索用时 15 毫秒
31.
目的了解基层医生有关手癣、足癣的诊治现状,分析影响因素,制定有针对性的措施。方法通过网络平台对全国19个省市的基层医生进行问卷调查。结果共回收完整问卷729份。结果显示:①约20%的基层医生对手、足癣的发病因素方面存在认识不足,约50%的基层医生对受侵犯皮肤的组织定位存在误区。②基层医生对手、足癣鉴别诊断的重要性重视不够,真菌镜检设备使用率不足一半。③基层医生能正确选用外用抗真菌药,硝酸咪康唑乳膏使用率超过80%。④仍有10.70%的基层医生推荐使用外用糖皮质激素治疗手、足癣。结论基层医生在手、足癣的规范诊疗方面仍有待提高。  相似文献   
32.
家蝇Phormicin作为防御素家族的成员,是一类具有广普抗菌活性的抗菌肽.本研究采用原核表达法表达并纯化获得了家蝇PhormicinA蛋白.将家蝇Phormicin A原核表达蛋白与完全佐剂和不完全佐剂乳化混匀,先后免疫新西兰白兔获得其多克隆抗体.通过原核表达蛋白中和吸附实验,以及Western blot实验验证了抗体的特异性.进一步用金黄色葡萄球菌刺激家蝇三龄幼虫样品,进行内源性验证并测定抗体的效价.结果 显示,该多克隆抗体既可以识别家蝇Phormicin A原核表达蛋白,也可以识别金黄色葡萄球菌刺激家蝇三龄幼虫产生的内源性Phormicin A蛋白.本研究为进一步探索Phormicin在家蝇天然免疫和防御中的机制等后续工作打下基础.  相似文献   
33.
Hepatocellular carcinoma (HCC) is one of the most aggressive tumours with marked fibrosis. Mycophenolate mofetil (MMF) was well-established to have antitumour and anti-fibrotic properties. To overcome the poor bioavailability of MMF, this study constructed two MMF nanosystems, MMF-LA@DSPE-PEG and MMF-LA@PEG-PLA, by covalently conjugating linoleic acid (LA) to MMF and then loading the conjugate into polymer materials, PEG5k-PLA8k and DSPE- PEG2k, respectively. Hepatocellular carcinoma cell lines and C57BL/6 xenograft model were used to examine the anti-HCC efficacy of nanoparticles (NPs), whereas NIH-3T3 fibroblasts and highly-fibrotic HCC models were used to explore the anti-fibrotic efficacy. Administration of NPs dramatically inhibited the proliferation of HCC cells and fibroblasts in vitro. Animal experiments revealed that MMF-LA@DSPE-PEG achieved significantly higher anti-HCC efficacy than free MMF and MMF-LA@PEG-PLA both in C57BL/6 HCC model and highly-fibrotic HCC models. Immunohistochemistry further confirmed that MMF-LA@DSPE-PEG dramatically reduced cancer-associated fibroblast (CAF) density in tumours, as the expression levels of alpha-smooth muscle actin (α-SMA), fibroblast activation protein (FAP) and collagen IV were significantly downregulated. In addition, we found the presence of CAF strongly correlated with increased HCC recurrence risk after liver transplantation. MMF-LA@DSPE-PEG might act as a rational therapeutic strategy in treating HCC and preventing post-transplant HCC recurrence.  相似文献   
34.
竹类植物是美国采集者在我国采集和引种的一类主要植物。在众多的竹类植物采集者中, 莫古礼(Floyd Alonzo McClure)是最具代表性的一位, 他于1919-1940年在岭南大学开展竹类植物研究, 在此期间多次采集竹类植物标本并引种竹类植物到美国。本研究通过大量文献研究、档案查阅以及实地调研, 整理了莫古礼采集竹类植物的路线和采集地, 并对竹类植物学名进行校对, 分析了莫古礼在华研究、采集和引种竹类植物的历史及其影响。经统计, 莫古礼在华期间竹类植物标本采集地涉及12个省级行政区39个地级市, 主要集中在广东、海南、香港等地; 引种地涉及9个省级行政区的25个地级市; 共采集竹类植物标本727号1,840份, 隶属20属93种(含种下单位, 下同), 分别占我国竹类植物属和种的58.8%和17.4%; 共引种竹类植物255份, 隶属于17属77种, 分别占我国竹类植物属和种的50.0%和14.4%。莫古礼在华采集和引种竹类植物极大地发展了竹类植物分类学, 所采集的竹类植物标本为后人竹类植物研究提供了极大的帮助, 所引种的竹类植物极大丰富了美国竹类植物种类, 也促进了竹类植物在美国的应用。  相似文献   
35.
JAK/STAT plays an important role in cytokine signal transduction and it is potentially involved in the proinflammatory response during the early phase of severe acute pancreatitis (SAP). However, whether JAK2 activity is upregulated and whether JAK2 inhibition plays a role in the maintenance of pancreatic homeostasis during SAP is incompletely understood. Here we show that JAK2/STAT3 activity is highly elevated in SAP and blockade of JAK2 by AG-490 protects against SAP-induced pancreatic inflammation and injury. Gene expression and ELISA studies showed that JAK2 inhibition altered the cytokine profiles in both the circulation and pancreases. Further analysis revealed that JAK2 inhibition restored the level of cytokines critical for macrophage polarization towards M2 macrophage. Our findings suggest that pharmacological targeting at JAK2/STAT signalling may be an effective choice of therapeutic interventions against SAP.  相似文献   
36.
Gaussia分泌型萤光素酶是近年发现的一种来源于海洋桡脚类动物Gaussia princeps的新型分泌型萤光素酶,是目前已知的可自然分泌的最小萤光素酶,因其分子小、灵敏度高、半衰期短和可高效分泌,而成为一种理想的报告基因,广泛应用于体内外研究。我们就Gaussia分泌型萤光素酶的发光原理、荧光特性及其应用等进行简要综述。  相似文献   
37.
38.
39.
Micro-indels (insertions or deletions shorter than 21 bps) constitute the second most frequent class of human gene mutation after single nucleotide variants. Despite the relative abundance of non-frameshifting indels, their damaging effect on protein structure and function has gone largely unstudied. We have developed a support vector machine-based method named DDIG-in (Detecting disease-causing genetic variations due to indels) to prioritize non-frameshifting indels by comparing disease-associated mutations with putatively neutral mutations from the 1,000 Genomes Project. The final model gives good discrimination for indels and is robust against annotation errors. A webserver implementing DDIG-in is available at http://sparks-lab.org/ddig.  相似文献   
40.

Background

With the establishment of minimally invasive surgery in society, the robot has been increasingly widely used in the urologic field, including in partial nephrectomy. This study aimed to comprehensively summarize the currently available evidence on the feasibility and safety of robotic partial nephrectomy for renal tumors of >4 cm.

Method and Findings

An electronic database search of PubMed, Scopus, Web of Science, and the Cochrane Library was performed. This systematic review and meta-analysis was based on all relevant studies that assessed robotic partial nephrectomy for renal tumors of >4 cm. Five studies were included. The meta-analysis involved 3 studies from 11 institutions including 154 patients, while the narrative review involved the remaining 2 studies from 5 institutions including 64 patients. In the meta-analysis, the mean ischemic time, operation time, and console time was 28, 319, and 189 minutes, respectively. The estimated blood loss and length of stay was 317 ml and 3.8 days, respectively. The rates of conversion, positive margins, intraoperative complications, postoperative complications, hilar clamping, and collecting system repair were 7.0%, 3.5%, 7.0%, 9.8%, 93.9%, and 47.5%, respectively. The narrative review showed results similar to those of the meta-analysis.

Conclusions

Robotic partial nephrectomy is feasible and safe for renal tumors of >4 cm with an acceptable warm ischemic time, positive margin rate, conversion rate, complication rate, operation time, estimated blood loss, and length of stay.  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