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   7917篇
  免费   630篇
  国内免费   53篇
耳鼻咽喉   35篇
儿科学   175篇
妇产科学   165篇
基础医学   1361篇
口腔科学   188篇
临床医学   789篇
内科学   1747篇
皮肤病学   232篇
神经病学   934篇
特种医学   214篇
外科学   818篇
综合类   25篇
一般理论   5篇
预防医学   508篇
眼科学   111篇
药学   611篇
中国医学   10篇
肿瘤学   672篇
  2024年   14篇
  2023年   119篇
  2022年   130篇
  2021年   393篇
  2020年   246篇
  2019年   296篇
  2018年   294篇
  2017年   248篇
  2016年   267篇
  2015年   265篇
  2014年   377篇
  2013年   433篇
  2012年   677篇
  2011年   608篇
  2010年   356篇
  2009年   343篇
  2008年   526篇
  2007年   476篇
  2006年   481篇
  2005年   460篇
  2004年   391篇
  2003年   363篇
  2002年   316篇
  2001年   68篇
  2000年   44篇
  1999年   59篇
  1998年   65篇
  1997年   52篇
  1996年   35篇
  1995年   38篇
  1994年   23篇
  1993年   17篇
  1992年   24篇
  1991年   13篇
  1990年   12篇
  1989年   7篇
  1988年   10篇
  1987年   7篇
  1986年   6篇
  1985年   9篇
  1984年   4篇
  1983年   2篇
  1982年   2篇
  1977年   4篇
  1942年   1篇
  1907年   2篇
  1906年   3篇
  1905年   3篇
  1904年   2篇
  1903年   4篇
排序方式: 共有8600条查询结果,搜索用时 312 毫秒
101.
The aim of this study was to analyze the impact of hydrodynamic forces on the multiplication of E. coli, and biofilm formation and dispersion. The experiments were provided in a flow chamber simulating a cleaning-in-place system. Biofilm biomass was measured using a crystal violet dye method. The results show that hydrodynamic forces affect not only biofilm formation and dispersion but the multiplication of E. coli in the first place. We found more biofilm biomass on the rough surface than on the smooth one. The results of the biofilm formation test show that laminar flow promotes the biofilm growth over 72 h, meanwhile turbulent flow after 48 h causes decrease in biomass. The results of the biofilm dispersion test, in contrast, show that laminar flow removed less biofilm from both materials that turbulent flow did. Therefore, taking into account these findings in cleaning-in-place technology can substantially reduce E. coli multiplication and biofilm formation.  相似文献   
102.
103.
104.
Monoclonal gammopathy of undetermined significance (MGUS) is a benign condition with an approximate 1% annual risk of symptomatic plasma cell disorder development, mostly to multiple myeloma (MM). We performed genomewide screening of copy‐number alterations (CNAs) in 90 MGUS and 33 MM patients using high‐density DNA microarrays. We identified CNAs in a smaller proportion of MGUS (65.6%) than in MM (100.0%, P = 1.31 × 10?5) and showed median number of CNAs is lower in MGUS (3, range 0–22) than in MM (13, range 4–38, P = 1.82 × 10?10). In the MGUS cohort, the most frequent losses were located at 1p (5.6%), 6q (6.7%), 13q (30.0%), 14q (14.4%), 16q (8.9%), 21q (5.6%), and gains at 1q (23.3%), 2p (6.7%), 6p (13.3%), and Xq (7.8%). Hyperdiploidy was detected in 38.9% of MGUS cases, and the most frequent whole chromosome gains were 3 (25.6%), 5 (23.3%), 9 (37.8%), 15 (23.3%), and 19 (32.2%). We also identified CNAs such as 1p, 6q, 8p, 12p, 13q, 16q losses, 1q gain and hypodiploidy, which are potentially associated with an adverse prognosis in MGUS. In summary, we showed that MGUS is similar to MM in that it is a genetically heterogeneous disorder, but overall cytogenetic instability is lower than in MM, which confirms that genetic abnormalities play important role in monoclonal gammopathies.  相似文献   
105.
In the last two decades it has become clear that hormones and gene mutations in endocrine signaling pathways can exert major effects on lifespan and related life history traits in worms, flies, mice, and other organisms. While most of this research has focused on insulin/insulin-like growth factor-1 signaling, a peptide hormone pathway, recent work has shown that also lipophilic hormones play an important role in modulating lifespan and other life history traits. Here we review how steroid hormones, a particular group of lipophilic hormones, affect life history traits in the nematode worm (Caenorhabditis elegans) and the fruit fly (Drosophila melanogaster), with a particular focus on longevity. Interestingly, a comparison suggests that parallel endocrine principles might be at work in worms and flies in these species and that steroid hormones interact with the gonad to affect lifespan.  相似文献   
106.
107.
We previously reported a system for assessing rejection in kidney transplant biopsies using microarray‐based gene expression data, the Molecular Microscope® Diagnostic System (MMDx). The present study was designed to optimize the accuracy and stability of MMDx diagnoses by replacing single machine learning classifiers with ensembles of diverse classifier methods. We also examined the use of automated report sign‐outs and the agreement between multiple human interpreters of the molecular results. Ensembles generated diagnoses that were both more accurate than the best individual classifiers, and nearly as stable as the best, consistent with expectations from the machine learning literature. Human experts had ≈93% agreement (balanced accuracy) signing out the reports, and random forest‐based automated sign‐outs showed similar levels of agreement with the human experts (92% and 94% for predicting the expert MMDx sign‐outs for T cell–mediated (TCMR) and antibody‐mediated rejection (ABMR), respectively). In most cases disagreements, whether between experts or between experts and automated sign‐outs, were in biopsies near diagnostic thresholds. Considerable disagreement with histology persisted. The balanced accuracies of MMDx sign‐outs for histology diagnoses of TCMR and ABMR were 73% and 78%, respectively. Disagreement with histology is largely due to the known noise in histology assessments (ClinicalTrials.gov NCT01299168).  相似文献   
108.
109.
Parasitology Research - Until recently Dirofilaria immitis, the causative agent of serious canine heartworm disease, has been detected relatively infrequently in Central Europe in comparison with...  相似文献   
110.

Two different video-taped short-term psychotherapies were rated on therapeutic alliance for 27 sessions. The ratings were based on two methods: the Penn Helping Alliance Scales (Penn-HAS) and the Therapeutic Alliance Rating Scale (TARS). Both scales provide separate scores for the therapist and the patient. After checking the reliabilities of the ratings, the strength and course of the alliance formation are compared within and across therapies. Furthermore it was hypothesized that the alliance is structured differently in the two therapies. This hypothesis is tested by making content-specific item comparisons across the therapies for the Penn-HAS and by a comparison of the factor structure over time (factor analytic P-technique) for the TARS.  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