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   3490篇
  免费   266篇
  国内免费   13篇
耳鼻咽喉   24篇
儿科学   105篇
妇产科学   57篇
基础医学   342篇
口腔科学   143篇
临床医学   483篇
内科学   579篇
皮肤病学   50篇
神经病学   227篇
特种医学   293篇
外科学   424篇
综合类   120篇
一般理论   3篇
预防医学   282篇
眼科学   108篇
药学   209篇
中国医学   16篇
肿瘤学   304篇
  2022年   22篇
  2021年   40篇
  2020年   21篇
  2019年   29篇
  2018年   41篇
  2017年   28篇
  2016年   26篇
  2015年   60篇
  2014年   94篇
  2013年   153篇
  2012年   134篇
  2011年   156篇
  2010年   101篇
  2009年   137篇
  2008年   132篇
  2007年   153篇
  2006年   130篇
  2005年   131篇
  2004年   138篇
  2003年   127篇
  2002年   121篇
  2001年   94篇
  2000年   99篇
  1999年   105篇
  1998年   106篇
  1997年   69篇
  1996年   86篇
  1995年   68篇
  1994年   63篇
  1993年   66篇
  1992年   63篇
  1991年   52篇
  1990年   64篇
  1989年   73篇
  1988年   78篇
  1987年   49篇
  1986年   70篇
  1985年   43篇
  1984年   51篇
  1983年   47篇
  1982年   37篇
  1981年   38篇
  1980年   34篇
  1979年   29篇
  1978年   39篇
  1977年   30篇
  1976年   27篇
  1975年   29篇
  1973年   20篇
  1970年   20篇
排序方式: 共有3769条查询结果,搜索用时 15 毫秒
51.
Morphological studies have shown that macrophages and microglia undergo apoptosis in the central nervous system (CNS) in acute experimental autoimmune encephalomyelitis (EAE) in the Lewis rat. To assess the relative levels of macrophage and microglial apoptosis, and the molecular mechanisms involved in this process, we used three-colour flow cytometry to identify CD45lowCD11b/c+ microglial cells and CD45highCD11b/c+ macrophages in the inflammatory cells isolated from the spinal cords of Lewis rats 13 days after immunization with myelin basic protein (MBP) and complete Freund's adjuvant. Simultaneously, we analyzed the DNA content of these cell populations to assess the proportions of cells undergoing apoptosis and in different stages of the cell cycle or examined their expression of three apoptosis- regulating proteins, i.e. Fas (CD95), Fas ligand (FasL) and Bcl-2. Microglia were highly vulnerable to apoptosis and were over-represented in the apoptotic population. Macrophages were less susceptible to apoptosis than microglia and underwent mitosis more frequently than microglia. The different susceptibilities of microglia and macrophages to apoptosis did not appear to be due to variations in Fas, FasL or Bcl- 2 expression, as the proportions of microglia and macrophages expressing these proteins were similar, and were relatively high. Furthermore, in contrast to T cell apoptosis, apoptosis of microglia/macrophages did not occur more frequently in cells expressing Fas or FasL, or less frequently in cells expressing Bcl-2. These results indicate that the apoptosis of microglia and CNS macrophages in EAE is not mediated through the Fas pathway, and that Bcl-2 expression does not protect them from apoptosis. Expression of FasL by macrophages and microglia may contribute to the pathogenesis and immunoregulation of EAE through interactions with Fas+ oligodendrocytes and Fas+ T cells. The high level of microglial apoptosis in EAE indicates that microglial apoptosis may be an important homeostatic mechanism for controlling the number of microglia in the CNS following microglial activation and proliferation.   相似文献   
52.
Influence of saccharide length on polysaccharide appetite in the rat   总被引:3,自引:0,他引:3  
The appetite of female rats for saccharides of different chain lengths was assessed in brief (5-min) one-bottle acceptance and two-bottle preference tests. The saccharides (and their lengths in glucose units) included glucose (1), maltose (2), maltotriose (3), maltooligosaccharide (4-8), maltopolysaccharide (average length 43), and Polycose (1 to 30+); 0.0125 and 0.025 molar solutions of these saccharides were tested. The results revealed that the rats' order of preference for these saccharides was as follows: maltooligosaccharide greater than maltotriose = maltose greater than glucose; and maltooligosaccharide greater than Polycose = maltopolysaccharide greater than maltose. Thus, as saccharide chain length increased from 1 to 4-8 glucose units palatability increased, but with further increases in chain length palatability declined somewhat. Previous findings have suggested that rats have a "polysaccharide" taste receptor and the present results indicate that the receptor is maximally (or near-maximally) stimulated by saccharides of 4-8 glucose units in length.  相似文献   
53.
Two Mannich-base prodrugs of 5-iodo-2-deoxycytidine (5-IDC) have been synthesized. The prodrugs exhibit increased lipid solubility compared to 5-IDC and rapidly revert to 5-IDC in buffer. One of the prodrugs delivered about twice as much 5-IDC from isopropyl myristate (IPM) through hairless mouse skin in diffusion-cell experiments as did 5-IDC from IPM. Subsequent applications of theophylline/ propylene glycol onto the diffusion cells to determine the effect of prodrug/IPM, 5-IDC/IPM, or IPM on the resistance of the skins to subsequent applications showed that the prodrug/IPM had no more effect than IPM itself.  相似文献   
54.
Prevention Science - We examined whether participation in adolescent substance use prevention programming can enhance long-term resilience into adulthood such that individuals were better able to...  相似文献   
55.
56.
57.
Influencing prescribing practices and the implementation of pharmaceutical care utilizing the drug use evaluation (DUE) process at a 891-bed teaching hospital are described. The DUE program has been structured to provide for significant pharmacy involvement while maintaining medical staff responsibility as outlined by the Joint Commission on Accreditation of Healthcare Organizations. A multidisciplinary approach is used to identify problems and develop prescribing criteria and educational initiatives. Pharmacists provide drug therapy monitoring and engage in clinical interventions and documentation of outcomes on a daily basis. DUE program pharmacists help target possible interventions, assure monitoring and outcome documentation, and compile results of all initiatives for reporting purposes to the medical staff and quality assessment program. Specific performance compliance and problems are identified and incorporated into the credentialing process. Corrective measures are determined by the Pharmacy and Therapeutics (P&T) Subcommittee with subsequent actions carried out by peer physicians. The net result is a positive influence on prescribing practices that improves the appropriate and effective use of drugs and improves patient outcomes.  相似文献   
58.
Valproate, an antiepileptic drug, is useful in the management of various nonepileptic disorders. It is an effective and generally well-tolerated medication for the treatment of bipolar disorder and has been approved by the Food and Drug Administration for use in manic states. Studies also suggest that it is effective in other bipolar spectrum illnesses. This report describes 2 clinical cases of DSM-IV bipolar disorder where valproate provided robust, sustained relief of mood symptoms. In the first case, valproate was chosen for initial therapy in a bipolar patient suffering from a mixture of hypomanic and depressive symptoms. In the second case, valproate replaced lithium in the management of a patient with an incomplete response to lithium plus an antidepressant. This report addresses relevant clinical issues and includes a brief review of the clinical pharmacology of valproate.  相似文献   
59.
60.
Radiographic techniques may be helpful in evaluation of the condition of paintings for their restoration, preservation, and occasionally to determine their authenticity. On the basis of experience with several of these procedures, the utility of each method is described in reference to specific "diagnoses" regarding paintings. Radiographic techniques have several advantages over other methods; they are nondestructive, they may be used to survey the entire painting, and they are subject to quantitative and serial analysis.  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