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   1291893篇
  免费   93640篇
  国内免费   2015篇
耳鼻咽喉   18319篇
儿科学   42930篇
妇产科学   38297篇
基础医学   188940篇
口腔科学   35613篇
临床医学   109956篇
内科学   254041篇
皮肤病学   26754篇
神经病学   100876篇
特种医学   50233篇
外国民族医学   366篇
外科学   199015篇
综合类   26624篇
现状与发展   1篇
一般理论   310篇
预防医学   94760篇
眼科学   29256篇
药学   98672篇
  2篇
中国医学   2523篇
肿瘤学   70060篇
  2018年   12512篇
  2016年   10517篇
  2015年   12143篇
  2014年   16681篇
  2013年   25264篇
  2012年   34841篇
  2011年   37325篇
  2010年   21933篇
  2009年   20642篇
  2008年   35925篇
  2007年   38913篇
  2006年   39372篇
  2005年   38578篇
  2004年   37097篇
  2003年   35971篇
  2002年   35497篇
  2001年   58191篇
  2000年   59640篇
  1999年   50774篇
  1998年   14310篇
  1997年   12884篇
  1996年   13132篇
  1995年   12378篇
  1994年   11796篇
  1993年   10894篇
  1992年   41014篇
  1991年   40389篇
  1990年   39913篇
  1989年   38735篇
  1988年   36130篇
  1987年   35376篇
  1986年   33742篇
  1985年   32165篇
  1984年   23939篇
  1983年   20831篇
  1982年   12388篇
  1981年   10939篇
  1979年   22643篇
  1978年   15887篇
  1977年   13732篇
  1976年   12977篇
  1975年   14203篇
  1974年   16689篇
  1973年   16081篇
  1972年   15324篇
  1971年   14232篇
  1970年   13215篇
  1969年   12740篇
  1968年   11985篇
  1967年   10479篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
942.
The effects of intracerebral implants of 17 beta estradiol and cholesterol in five brain regions were tested on the duration of the dorsal immobility response in ovariectomized female rats. The dorsal immobility response was significantly prolonged by 4-hr implants of 17 beta estradiol in the dorsal striatum and nucleus accumbens, but not in the cortex, the globus pallidus, or the substantia nigra pars compacta. These data further support previous evidence that estradiol acts directly on the striatum to affect behavior in the rat.  相似文献   
943.
D J Harris  G O Waring  L L Burk 《Ophthalmology》1989,96(11):1597-1607
After penetrating keratoplasty in 52 eyes, keratography refraction and keratometry were used to select appropriate interrupted sutures for removal in order to reduce astigmatism. All eyes had one continuous and either 12 or 16 interrupted nylon sutures. The keratographs were examined retrospectively and separated into six groups on the basis of similar mire patterns. The removal of single sutures associated with three of these patterns reduced astigmatism by the following average amounts: symmetrical oval pattern, 0.44 diopters (D); D-shaped oval pattern, 2.07 D; and focal indentation pattern, 6.60 D. The other three patterns--mildly disrupted mires, incomplete mires, and uninterpretable mires--did not allow quantification of results. Examples of these keratographic patterns are presented and recommendations are made for their use in the management of astigmatism following penetrating keratoplasty.  相似文献   
944.
N-Hydroxythalidomide (1d), a potential metabolite of thalidomide (1a), was synthesized from N-phthalyglutaminic acid anhydride (1b) and O-tetrahydropyraline hydroxylamine, followed by deprotection. The teratogenicity of 1d was studied using the Hen's-Egg-Test model which had been found applicable for 1a. 1d was more teratogenic to chicken embryos compared to 1a. The percentage of teratogenic malformations in the 1d groups was 28-46%, whereas the percentage in the 1a groups was 20-23%. The oxygen protected precursor N-hydroxythalidomide (1c) was less teratogenic (11-15%).  相似文献   
945.
Two antifungal antibiotics maniwamycins A and B were isolated from the culture broth of a strain of actinomycetes, which were classified as Streptomyces prasinopilosus. These antibiotics were isolated by resin absorption and extraction with EtOAc and purified by column chromatography. Both antibiotics were found to be new azoxy substances from their physico-chemical properties. They showed broad antifungal spectra.  相似文献   
946.
A series of new 4-aryl-5-[omega-(4-aryl-1-piperazinyl)alkyl]-2(3H)- oxazolones was synthesized and tested for neuroleptic activity in mice and rats. Several compounds exhibited interesting neuroleptic activity with very low liability to the extrapyramidal side effects. In particular the activity of 4-(4-fluorophenyl)-5-[2-[4-(3,5-dichlorophenyl)-1- piperazinyl]ethyl]-2(3H)-oxazolone (14) was greater than that of butropipazone and fluanisone, while of the same order of that of chlorpromazine; however, the product showed a longer lasting activity and minor ability to produce catalepsy as compared with the reference drugs.  相似文献   
947.
Mycobacterium ulcerans infection in Ashanti region, Ghana   总被引:1,自引:0,他引:1  
We describe a series of 96 cases of Mycobacterium ulcerans infection (Buruli ulcer) from a new endemic focus in the Afram valley, north of Agogo, in Ghana. 63 cases were children under 13 years old. Active treatment by excision and skin grafting necessitates long stays in hospital and repeated procedures. Scarring and contracture are frequent. Eyes and other vital organs may be destroyed. In its endemic foci Buruli ulcer is a serious health burden on rural populations. Research is urgently needed, especially in prevention and non-surgical management.  相似文献   
948.
949.
950.
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