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   1546篇
  免费   113篇
  国内免费   1篇
  2022年   8篇
  2021年   23篇
  2020年   14篇
  2019年   22篇
  2018年   26篇
  2017年   17篇
  2016年   26篇
  2015年   64篇
  2014年   80篇
  2013年   78篇
  2012年   153篇
  2011年   107篇
  2010年   81篇
  2009年   58篇
  2008年   100篇
  2007年   92篇
  2006年   109篇
  2005年   83篇
  2004年   75篇
  2003年   69篇
  2002年   48篇
  2001年   17篇
  2000年   11篇
  1999年   13篇
  1998年   12篇
  1997年   16篇
  1996年   9篇
  1995年   6篇
  1994年   9篇
  1993年   7篇
  1991年   6篇
  1990年   7篇
  1989年   10篇
  1988年   12篇
  1987年   17篇
  1986年   16篇
  1985年   12篇
  1984年   8篇
  1983年   7篇
  1982年   10篇
  1980年   7篇
  1979年   14篇
  1978年   14篇
  1977年   8篇
  1976年   9篇
  1975年   10篇
  1973年   8篇
  1972年   10篇
  1971年   5篇
  1966年   5篇
排序方式: 共有1660条查询结果,搜索用时 78 毫秒
51.
The results of computing the structure of the resistant and susceptible stands bear evidence that in a resistant one, about 20% trees have low resistance and compose a limited trophical niche of the pest. The checking up of this suggestion conducted in a region with different ecological conditions (the central part of Ukraine), confirms it. Hence, a resistant stand must consist of a definite level of the resistant pine groups rather than exclusively resistant ones even at polygenic control the resistance. We have conducted the systematization of information from observations as to the damage scale of the pine and a number of cultured plant species by specialized pest insects. The aim of this systematization is the checking up of the regularity of the structure of resistant stands of the pine and cultured plants that are damage‐resistant. The analysis of the study's results bears evidence of the presence of the determined regularity in the structure of resistant biocenoses independent of species or varieties of the plants and also the specialized pests.  相似文献   
52.
53.
We analysed the structure of deeply knotted proteins representing three unrelated families of knotted proteins. We looked at the correlation between positions of knotted cores in these proteins and such local structural characteristics as the number of intra-chain contacts, structural stability and solvent accessibility. We observed that the knotted cores and especially their borders showed strong enrichment in the number of contacts. These regions showed also increased thermal stability, whereas their solvent accessibility was decreased. Interestingly, the active sites within these knotted proteins preferentially located in the regions with increased number of contacts that also have increased thermal stability and decreased solvent accessibility. Our results suggest that knotting of polypeptide chains provides a favourable environment for the active sites observed in knotted proteins. Some knotted proteins have homologues without a knot. Interestingly, these unknotted homologues form local entanglements that retain structural characteristics of the knotted cores.  相似文献   
54.

Background

Many studies have assessed emotion recognition in patients with Borderline Personality Disorder and considerable evidence has been accumulated on patients’ ability to categorize emotions. In contrast, their ability to detect emotions has been investigated sparsely. The only two studies that assessed emotion detection abilities found contradictory evidence on patients’ ability to detect angry faces.

Methods

To clarify whether patients with Borderline Personality Disorder show enhanced detection of angry faces, we conducted three experiments: a laboratory study (n = 53) with a clinical sample and two highly powered web studies that measured Borderline features (n1 = 342, n2 = 220). Participants in all studies completed a visual search paradigm, and the reaction times for the detection of angry vs. happy faces were measured.

Results

Consistently, data spoke against enhanced detection of angry faces in the Borderline groups, indicated by non-significant group (Borderline vs. healthy control) × target (angry vs. happy) interactions, despite highly satisfactory statistical power to detect even small effects.

Conclusions

In contrast to emotion categorization, emotion detection appears to be intact in patients with Borderline Personality Disorder and individuals high in Borderline features. The importance of distinguishing between these two processes in future studies is discussed.  相似文献   
55.
Head and neck squamous cell carcinoma is the sixth leading cause of cancer worldwide. The most common risk factors are carcinogens (tobacco, alcohol), and infection of the human papilloma virus. Surgery is still considered as the treatment of choice in case of head and neck cancer, followed by a reconstructive surgery to enhance the quality of life in the patients. However, the widespread use of artificial implants does not provide appropriate physiological activities and often cannot act as a long-term solution for the patients. Here we review the applicability of multiple stem cell types for tissue engineering of cartilage, trachea, vocal folds and nerves for head and neck injuries. The ability of the cells to self-renew and maintain their pluripotency state makes them an attractive tool in tissue engineering.  相似文献   
56.
57.
Understanding the nature of mucus-microbe interactions will provide important information that can help to elucidate the mechanisms underlying probiotic adhesion. This study focused on the adhesive properties of the Lactococcus lactis subsp. cremoris IBB477 strain, previously shown to persist in the gastrointestinal tract of germ-free rats. The shear flow-induced detachment of L. lactis cells was investigated under laminar flow conditions. Such a dynamic approach demonstrated increased adhesion to bare and mucin-coated polystyrene for IBB477, compared to that observed for the MG1820 control strain. To identify potential genetic determinants giving adhesive properties to IBB477, the improved high-quality draft genome sequence comprising chromosome and five plasmids was obtained and analysed. The number of putative adhesion proteins was determined on the basis of surface/extracellular localisation and/or the presence of adhesion domains. To identify proteins essential for the IBB477 specific adhesion property, nine deletion mutants in chromosomal genes have been constructed and analysed using adhesion tests on bare polystyrene as well as mucin-, fibronectin- or collagen IV-coated polystyrene plates in comparison to the wild-type strain. These experiments demonstrated that gene AJ89_07570 encoding a protein containing DUF285, MucBP and four Big_3 domains is involved in adhesion to bare and mucin-coated polystyrene. To summarise, in the present work, we characterised the adhesion of IBB477 under laminar flow conditions; identified the putative adherence factors present in IBB477, which is the first L. lactis strain exhibiting adhesive and mucoadhesive properties to be sequenced and demonstrated that one of the proteins containing adhesion domains contributes to adhesion.  相似文献   
58.
59.
Human Papillomavirus (HPV) remains one of the most commonly contracted sexually transmitted diseases around the world. There are a multitude of HPV types, some of which may never present any symptoms. Others, however, are considered high-risk types, which increase the chance of the person infected to develop cancer. In recent years, the utilization of nanotechnology has allowed researchers to employ and explore the use of nanoparticles in immunotherapies.The new nanoparticle frontier has opened many doors in this area of research as a form of prevention, diagnosis, and treatment in cancers resulting from HPV. This review will provide a brief background of HPV, its relationship to head and neck cancer (HNC) and present some insight into the field of immunotherapeutic nanoparticles.  相似文献   
60.
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