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   39580篇
  免费   3356篇
  国内免费   527篇
耳鼻咽喉   437篇
儿科学   1086篇
妇产科学   938篇
基础医学   5221篇
口腔科学   872篇
临床医学   4159篇
内科学   7221篇
皮肤病学   867篇
神经病学   3519篇
特种医学   1318篇
外国民族医学   3篇
外科学   5253篇
综合类   1554篇
一般理论   36篇
预防医学   3345篇
眼科学   999篇
药学   2950篇
  4篇
中国医学   355篇
肿瘤学   3326篇
  2023年   223篇
  2022年   469篇
  2021年   858篇
  2020年   526篇
  2019年   761篇
  2018年   813篇
  2017年   697篇
  2016年   731篇
  2015年   949篇
  2014年   1182篇
  2013年   1729篇
  2012年   2391篇
  2011年   2600篇
  2010年   1536篇
  2009年   1347篇
  2008年   2249篇
  2007年   2266篇
  2006年   2236篇
  2005年   2166篇
  2004年   1994篇
  2003年   1837篇
  2002年   1710篇
  2001年   846篇
  2000年   740篇
  1999年   788篇
  1998年   477篇
  1997年   417篇
  1996年   412篇
  1995年   372篇
  1994年   335篇
  1993年   320篇
  1992年   495篇
  1991年   483篇
  1990年   464篇
  1989年   411篇
  1988年   361篇
  1987年   300篇
  1986年   356篇
  1985年   317篇
  1984年   311篇
  1983年   281篇
  1982年   312篇
  1981年   281篇
  1980年   231篇
  1979年   251篇
  1978年   188篇
  1977年   181篇
  1976年   166篇
  1974年   203篇
  1972年   161篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
Summary Deaza-aminopterin is a folate analog which is transported more rapidly than methotrexate into cells and appears to be more active than methotrexate against human and animal tumor in vitro. Fifteen patients with advanced urothelial tract cancer were given deaza-aminopterin 30–37.5 mg/m2 IV QW. In responding patients drug was given QOW after 4–6 consecutive doses. Doses were escalated or de-escalated by 7.5 mg/m2 depending on toxicity. Twelve patients had received prior chemotherapy which included methotrexate in nine. Three patients achieved a partial remission lasting 1, 3, and 3 months respectively: all responders had previously failed methotrexate after an initial response to a methotrexate containing regimen. None of the six patients who were methotrexate naive responded to deaza-aminopterin; 3 subsequently received methotrexate without response. Mild mucositis was universal and in 5 was severe. Six patients had an increase in liver transaminases probably secondary to anti-folate hepatotoxicity. Other toxicities included diarrhea, nausea, skin rash and fever. Further studies are needed to define the precise efficacy of deaza-aminopterin in patients with urothelial tract cancers.  相似文献   
32.
33.
34.
35.
研究大学生心理素质与思想品德发展的关系,目的在于分析、发现个体在接受教育过程中的心理运动规律,从而提高思想教育的实效性。本文从马克思主义认识论和实践论的观点出发,依据教育心理学的原理,探讨了心理健康教育与思想品德教育的内在联系和相互作用,提出良好的心理素质是大学生思想品德发展的基础的观点。认为品德的形成与人的心理活动息息相关,个体如果没有良好的品德,将影响其心理素质的完善;同样,没有健全的心理素质,思想品德也不能得到很好的发展。只有思想品德教育与心理健康教育协调发展,共同作用,才能收到良好的教育效果。  相似文献   
36.
In 151 years since first described, there have been 112 reported cases of hernia through the foramen of Winslow (HFW). All thus far have described HFW as a primary entity. The case reported appears to be unique with HFW as a surgical complication. HFW is the least common of internal hernias. The primary symptom is pain referred from the herniated organ and the hepatoduodenal ligament. An interesting sign is that the patient is found curled up or stooped over for pain relief. Anatomic factors implicated in HFW are an enlarged epiploic foramen, a floppy cecum and ascending colon, or abnormal length of small bowel mesentery. Tension on these structures causes pain with the torso extended. Distention of bowel in the lesser sac mimics gastric obstruction. Organs herniated are: small bowel (63%); cecum, ascending colon, and terminal ileum (30%); and transverse colon (7%). Of 25 cases reported since 1966, cecal herniation comprised two-thirds. The diagnosis may be made radiologically and the treatment is surgical. The case and a review of the literature are presented with attention to the anatomy. Also provided are the signs and symptoms of this interesting and perplexing diagnosis.  相似文献   
37.
The hypothesis that neuroblasts migrate in the nervous system by a locomotory process was tested experimentally. An in vitro preparation permitted direct observation of postmitotic cells migrating from the rhombic lip of the medulla and the anlage of the cochleovestibular ganglion. Cell locomotion was not seen. Instead migration was produced by elongation of a leading process, followed by translocation of the nucleus (perikaryal translocation). On the basis of comparisons with previous observations in situ, we propose that this represents a common mode of migration in the developing nervous system. Cell clusters were explanted from the rhombic lip at the developmental stage when they migrate from the ventricular zone to the acoustico-vestibular anlage in the medulla. Cells from the cochleovestibular ganglion were explanted after migration from the otocyst, but before ganglionic differentiation. Each neuroblast's migration route was formed by an elongating leading process ending in a growth cone. The growth cone attached to other cells and processes or ended freely on an acellular substrate. Nonneuronal cells usually migrated as has been described for fibroblasts, yet with some of the features of perikaryal translocation, but some nonneuronal precursor cells may migrate the way neuroblasts do. Neuroblasts did not migrate preferentially on the processes of nonneuronal cells, although the reverse could be observed. In fact a variety of interactions between migratory cells, neuronal and nonneuronal, were observed. The advantage of the experimental system described here is that one can observe cells migrating spontaneously at the times in development when they normally do so, while preserving the cellular populations present in situ.  相似文献   
38.
While much time has been spent deliberating about the definition of play, little emphasis has been placed on what children themselves perceive as play. The aim of the present study was to examine social context as a cue for children's perceptions of play and learning. Ninety-two children aged between four and six years (mean four years nine months) participated in the study and completed the Activity Apperception Story Procedure. Children were asked to sort photographic stimuli into those they believed depicted play/not play and learning/not learning. Each of the stimuli were identified by independent raters as containing one of the following social cues; teacher absence (solitary activity, parallel activity or cooperative activity) or teacher presence (teacher involved activity or teacher directed activity). Findings revealed that children associated teacher absence with play. More specifically, children made links between play and the presence of peers (parallel and cooperative activity). Findings are discussed in relation to play in the early years curriculum, differences in children's early educational experiences and the importance of understanding children's perceptions of play.  相似文献   
39.
T-2 toxin is one of the mycotoxins, a group of type A trichothecenes produced by several fungal genera including Fusarium species. In the present study, we have investigated the apoptotic effects of T-2 toxin on chondrocytes and the relationship between T-2 toxin induced chondrocyte apoptosis and its influence on Bcl-2/Bax protein and mRNA expression. We have also examined the inhibitory effects of selenium on chondrocyte apoptosis induced by T-2 toxin. We have combined morphological and biological techniques to establish the relevance of apoptosis in human chondrocyte death induced by T-2 toxin. Treatment with T-2 toxin caused accelerated apoptosis in a concentration dependent manner. The apoptosis induced by T-2 toxin involved an increased Bax/Bcl-2 ratio. Bcl-2 mRNA expression remained unchanged in chondrocyte apoptosis induced by T-2 toxin treatment, while Bax mRNA expression increased following treatment with T-2 toxin. Selenium could partly block the apoptosis of chondrocytes induced by T-2 toxin through decreasing the Bax/Bcl-2 ratio. These results suggest that, under our experimental conditions, apoptosis of chondrocytes can be induced by T-2 toxin (1-20ng/mL) via the Bcl-2 and Bax proteins, and the Bax/Bcl-2 ratio may play a critical role in governing the susceptibility to apoptosis induced by T-2 toxin in human chondrocytes.  相似文献   
40.
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