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   177280篇
  免费   10806篇
  国内免费   469篇
耳鼻咽喉   2256篇
儿科学   5689篇
妇产科学   3715篇
基础医学   24337篇
口腔科学   7679篇
临床医学   13176篇
内科学   39885篇
皮肤病学   4554篇
神经病学   15027篇
特种医学   5482篇
外国民族医学   26篇
外科学   21767篇
综合类   1409篇
现状与发展   1篇
一般理论   66篇
预防医学   18247篇
眼科学   3271篇
药学   10868篇
中国医学   697篇
肿瘤学   10403篇
  2023年   929篇
  2022年   2098篇
  2021年   3985篇
  2020年   2660篇
  2019年   3699篇
  2018年   5087篇
  2017年   3843篇
  2016年   3603篇
  2015年   4181篇
  2014年   5754篇
  2013年   7222篇
  2012年   11264篇
  2011年   11684篇
  2010年   5946篇
  2009年   5370篇
  2008年   9087篇
  2007年   9651篇
  2006年   8991篇
  2005年   9251篇
  2004年   8663篇
  2003年   7917篇
  2002年   5933篇
  2001年   5010篇
  2000年   4986篇
  1999年   4396篇
  1998年   1602篇
  1997年   1331篇
  1996年   1303篇
  1995年   1110篇
  1994年   1092篇
  1993年   989篇
  1992年   2683篇
  1991年   2577篇
  1990年   2358篇
  1989年   2339篇
  1988年   2118篇
  1987年   1961篇
  1986年   1833篇
  1985年   1762篇
  1984年   1262篇
  1983年   1013篇
  1982年   573篇
  1981年   515篇
  1980年   493篇
  1979年   925篇
  1978年   607篇
  1977年   479篇
  1975年   545篇
  1974年   540篇
  1973年   544篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
This study is focussed on micro-encapsulation of essential oils in polylactic acid (PLA) and a poly(methyl methacrylate) (PMMA) matrix as well as blends of the same. Microspheres were prepared by the solvent evaporation technique and characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR). The encapsulation efficiencies and release profiles of the essential oils were studied by gas chromatography mass spectrometry (GC-MS) and head-space solid-phase microextraction GC-MS, respectively. Furthermore, the microspheres were tested for antibacterial activity against both Gram-negative and Gram-positive bacterial strains.

The results showed that the microspheres compositions (PLA/PMMA ratio) have significant effect on their characteristics. The process adopted for preparing the microspheres promoted formation of spherical particles at the sizes of 1.5–9.5?µm. The highest encapsulation efficiency of the prepared microspheres was observed in systems consisting of linalool (81.10?±?10.0?wt. % for PLA system and 76.0?±?3.3?wt. % for PMMA system). Confirmation was also made that the release rate of the microspheres was affected by the size of the same.  相似文献   

4.
5.
Neorickettsia helminthoeca (NH), the agent of salmon poisoning disease or canine neorickettiosis (CN), is a bacterial endosymbiont of the nematode Nanophyetus salmincola, and infections are spreading among specific fish‐eating mammalians. This article describes the pathologic and immunohistochemical findings associated with spontaneous NH‐induced infections in dogs from Southern Brazil. The principal pathologic findings were hypertrophy of Peyer patches and lymphadenopathy with lymphocytic proliferation, chronic interstitial pneumonia, and chronic enteritis associated with positive intralesional immunoreactivity to antigens of NH within macrophages and histiocytes. Positive immunoreactivity against canine parvovirus‐2 (CPV‐2) or/and canine distemper virus was not detected in the evaluated intestinal segments or in the samples from the cerebellum and lungs, respectively, from the dogs evaluated. These findings demonstrated that NH was involved in the enteric, pulmonary, and lymphoid lesions herein described, and provide additional information to confirm the occurrence of this bacterial endosymbiont within this geographical location. It is proposed that chronic pneumonia should be considered as a pathologic manifestation of NH‐induced infections. Additionally, our results show that the occurrences of CN seem to be underdiagnosed in Southern Brazil due to the confusion with the incidence of CPV‐2.  相似文献   
6.
7.
8.
Depigmented lesions may occur as postinflammatory sequelae of subacute cutaneous lupus erythematosus (SCLE), leading to great psychosocial impact. A 53‐year‐old male patient presented with post‐SCLE depigmented facial lesions after five years of disease stability. We proposed surgical treatment with melanocyte‐keratinocyte transplantation procedure (MKTP), and after five months the patient achieved 90% repigmentation, without Koebner phenomenon (KP). In theory, KP is a possible complication of MKTP procedure since the preparation of the receptor area involves the use of dermabrasion. In an attempt to avoid it, we suggest to maintain the treatment of the underlying disease and wait for a minimum period of disease stability before the procedure.  相似文献   
9.
10.
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