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   350篇
  免费   108篇
  国内免费   3篇
  461篇
  2021年   4篇
  2018年   4篇
  2017年   6篇
  2016年   8篇
  2015年   9篇
  2014年   14篇
  2013年   18篇
  2012年   24篇
  2011年   32篇
  2010年   11篇
  2009年   17篇
  2008年   26篇
  2007年   17篇
  2006年   18篇
  2005年   17篇
  2004年   18篇
  2003年   21篇
  2002年   12篇
  2001年   13篇
  2000年   21篇
  1999年   7篇
  1998年   14篇
  1997年   5篇
  1995年   2篇
  1994年   3篇
  1993年   2篇
  1992年   6篇
  1991年   2篇
  1990年   8篇
  1989年   5篇
  1988年   4篇
  1987年   9篇
  1986年   5篇
  1985年   7篇
  1984年   9篇
  1983年   6篇
  1982年   7篇
  1981年   3篇
  1980年   5篇
  1979年   4篇
  1978年   2篇
  1977年   2篇
  1976年   5篇
  1975年   2篇
  1974年   3篇
  1972年   2篇
  1971年   3篇
  1969年   2篇
  1968年   2篇
  1954年   2篇
排序方式: 共有461条查询结果,搜索用时 15 毫秒
141.
142.
Temporal fossa bone grafts: a new technique in craniofacial surgery   总被引:1,自引:0,他引:1  
The calvarium has become an increasingly popular bone-graft donor site. Previously described harvesting techniques are often difficult to perform and may produce unsatisfactory bone fragments. However, full-thickness bone grafts taken from the region of the temporal fossa, beneath the temporaiis muscle, have proven to be of high quality and technically easy to obtain. In our experience with eight patients, temporal fossa bone grafts were used primarily around the orbit, including reconstruction of the orbital floor, frontal bone, and zygoma. The procedure begins with a hemicoronal or bicoronal incision; the temporalis muscle is reflected, and an underlying bone plate up to 4 X 6 cm is removed. The resulting bone graft is consistently 3 to 4 mm in thickness. The cranial defect is packed with bone debris, and the muscle is replaced. This technique has proven to be safe, technically simple, consistently productive of high-quality bone grafts, and within discernible donor-site deformity.  相似文献   
143.
The herpes simplex virus glycoprotein designated VP7(B2) is extracted from virions by nonionic detergent in the form of an oligomer, whereas the other detergent-soluble envelope proteins appear to be extracted as monomers. The subunits of the VP7(B2) oligomer cannot be dissociated by 2-mercaptoethanol and are also resistant to dissociation by a mixture of sodium dodecyl sulfate and 2-mercaptoethanol, except at elevated temperature. The oligomeric form of solubilized VP7(B2) appears to be predominantly dimeric, based on the sedimentation rats in sucrose gradients and the electrophoretic mobilities in sodium dodecyl sulfate-containing acrylamide gels of the undissociated and heat-dissociated forms of VP7(B2).  相似文献   
144.
Triggered by a fascinating publication in the New England Journal of Medicine detailing China's new multi-pronged strategy to control and eventually interrupt the transmission of Schistosoma japonicum, this PLoS Neglected Tropical Diseases Debate critically examines the generalizability and financial costs of the studies presented from the marshlands of the lake region. Edmund Seto from the University of California and colleagues emphasize that the epidemiology and control of schistosomiasis varies according to the social-ecological context. They conjecture that the successful intervention packages piloted in the lake region is not fully fit for the hilly and mountainous environments in Sichuan and Yunnan provinces, and hence call for more flexible, setting-specific, and less expensive control strategies. In response, Xiao-Nong Zhou from the National Institute of Parasitic Diseases at the Chinese Center of Disease Control and Prevention and colleagues explain the steps from designing pilot studies to the articulation and implementation of a new national control strategy through a careful process of scaling-up and adaptations. Finally, the two opponents converge. The need for integrated, intersectoral, and setting-specific control measures is stressed, supported by rigorous surveillance and continuous research. Experiences and lessons from China are important for shaping the schistosomiasis elimination agenda.  相似文献   
145.
When amphetamine is associated with a tastant conditioned stimulus, rats learn to avoid the taste even when employing doses that promote conditioned place preference. One hypothesis raised to account for this effect proposes that taste avoidance induced by amphetamine may be motivated by fear. A sensitive period has been identified in the rat (until postnatal day 10) in which infants learn conditioned appetitive effects to stimuli to which aversions are conditioned after this period. Exogenous administration of corticosterone within this period reverses this effect, generating aversive conditioning. In the present study, we tested conditioning of aversions to amphetamine or LiCl, within and after the sensitive period (Experiments 1 and 2). A third experiment evaluated unconditioned rejection of an aversive quinine solution within the sensitive period. Finally, we tested whether corticosterone administration before conditioning modulates amphetamine-induced taste avoidance. After the sensitive period, infant rats rejected the solution paired with amphetamine or LiCl after 2 conditioning trials, but within the sensitive period, aversions were conditioned only by LiCl and after 4 conditioning trials. Amphetamine-induced taste avoidance was not observed even when corticosterone was administered before conditioning. Additionally, during the sensitive period, a low LiCl dose promoted conditioned taste preference. According to Experiment 3, parameters employed in this study were suitable to yield rejection of aversive solutions within the sensitive period. These results suggest that during the sensitive period, there is a notable resistance to the acquisition of taste avoidance induced by amphetamine. The present experimental framework may represent a useful tool for studying mechanisms underlying taste avoidance and aversion effects.  相似文献   
146.
147.
S Li  D Cullen  M Hjort  R Spear    J H Andrews 《Applied microbiology》1996,62(5):1514-1518
Aureobasidium pullulans, a cosmopolitan yeast-like fungus, colonizes leaf surfaces and has potential as a biocontrol agent of pathogens. To assess the feasibility of rRNA as a target for A. pullulans-specific oligonucleotide probes, we compared the nucleotide sequences of the small-subunit rRNA (18S) genes of 12 geographically diverse A. pullulans strains. Extreme sequence conservation was observed. The consensus A. pullulans sequence was compared with other fungal sequences to identify potential probes. A 21-mer probe which hybridized to the 12 A. pullulans strains but not to 98 other fungi, including 82 isolates from the phylloplane, was identified. A 17-mer highly specific for Cladosporium herbarum was also identified. These probes have potential in monitoring and quantifying fungi in leaf surface and other microbial communities.  相似文献   
148.
149.
150.
Polyclonal and monoclonal antibodies to individual herpes simplex virus (HSV) glycoproteins were tested for ability to inhibit adsorption of radiolabeled HSV type 1 (HSV-1) strain HFEMsyn [HSV-1(HFEM)syn] to HEp-2 cell monolayers. Polyclonal rabbit antibodies specific for glycoprotein D (gD) or gC and three monoclonal mouse antibodies specific for gD-1 or gC-1 most effectively inhibited HSV-1 adsorption. Antibodies of other specificities had less or no inhibitory activity despite demonstrable binding of the antibodies to virions. Nonimmune rabbit immunoglobulin G and Fc fragments partially inhibited adsorption when used at relatively high concentrations. These results suggest involvement of gD, gC, and perhaps gE (the Fc-binding glycoprotein) in adsorption. The monoclonal anti-gD antibodies that were most effective at inhibiting HSV-1 adsorption had only weak neutralizing activity. The most potent anti-gD neutralizing antibodies had little effect on adsorption at concentrations significantly higher than those required for neutralization. This suggests that, although some anti-gD antibodies can neutralize virus by blocking adsorption, a more important mechanism of neutralization by anti-gD antibodies may be interference with a step subsequent to adsorption, possibly penetration.  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