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   81687篇
  免费   7037篇
  国内免费   3792篇
耳鼻咽喉   939篇
儿科学   985篇
妇产科学   1432篇
基础医学   11660篇
口腔科学   1940篇
临床医学   8313篇
内科学   14343篇
皮肤病学   1342篇
神经病学   5300篇
特种医学   2776篇
外国民族医学   22篇
外科学   9957篇
综合类   8916篇
现状与发展   8篇
一般理论   11篇
预防医学   5107篇
眼科学   2238篇
药学   7941篇
  19篇
中国医学   2516篇
肿瘤学   6751篇
  2024年   102篇
  2023年   658篇
  2022年   1513篇
  2021年   2084篇
  2020年   1543篇
  2019年   1662篇
  2018年   2196篇
  2017年   1936篇
  2016年   1848篇
  2015年   2319篇
  2014年   3040篇
  2013年   3194篇
  2012年   4466篇
  2011年   4557篇
  2010年   2777篇
  2009年   2459篇
  2008年   3448篇
  2007年   3513篇
  2006年   3276篇
  2005年   2943篇
  2004年   2370篇
  2003年   2291篇
  2002年   2084篇
  2001年   5254篇
  2000年   5100篇
  1999年   4476篇
  1998年   1762篇
  1997年   1355篇
  1996年   875篇
  1995年   780篇
  1994年   691篇
  1993年   588篇
  1992年   2118篇
  1991年   1850篇
  1990年   1651篇
  1989年   1607篇
  1988年   1411篇
  1987年   1272篇
  1986年   1126篇
  1985年   956篇
  1984年   612篇
  1983年   502篇
  1982年   255篇
  1981年   194篇
  1980年   153篇
  1979年   294篇
  1978年   84篇
  1974年   82篇
  1973年   104篇
  1972年   75篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Both dopamine D1 and D2 receptors are present in rat retina. D1 receptors are positively coupled to adenylyl cyclase, while D2 receptors are negatively coupled. After intraocular administration of the neurotoxin 6-hydroxydopamine (6-OHDA) there is depletion of retinal dopamine by about 90%, as well as a decrease of the number of D1 and D2 receptor binding sites. Following the 6-OHDA lesion, there is an enhancement of the D1 receptor-stimulated accumulation of cyclic-AMP and a loss of D2 receptor-inhibited accumulation of cyclic-AMP. Our results suggest that some of the retinal D2 receptors are coupled to adenylyl cyclase and some are not.  相似文献   
42.
目的 :观察天然碱性脂 (Stearylamine,SA)脂质体介导绿色荧光蛋白 /碱性成纤维细胞生长因子(GFP/bFGF)基因于不同时间段豚鼠耳蜗中的表达 ,为进一步研究耳聋的基因治疗提供实验基础。方法 :取豚鼠 1 6只 ,分成 4组 ,每组 4只。其中 3只右耳圆窗内注入SA -GFP/bFGF复合物 ,1只同法注入生理盐水作为对照。分别于术后第 2、7、1 4、2 1天取材。在荧光显微镜下观察GFP的表达 ,用免疫组化法检测bFGF的转导情况。结果 :荧光显微镜下见双侧耳蜗于术后第 2天开始部分细胞发出绿色荧光 ,第 7天达到高峰 ,支持细胞及内外毛细胞均显荧光 ,细胞轮廓清晰 ;第 1 4天开始减弱 ,第 2 1天消失。免疫组化染色显示 ,除血管纹外 ,耳蜗各回Corti器、螺旋韧带、螺旋缘及螺旋神经节细胞均有高浓度的表达产物 ,对照动物呈阴性表达。结论 :SA脂质体介导的GFP/bFGF基因单耳给药双侧耳蜗均有高效表达 ,为进一步研究基因治疗耳聋提供了可能。  相似文献   
43.
44.
OBJECTIVES: The aim was to assess the natural course of oral lichen lesions (OLL) among unselected, non-consulting individuals. SUBJECTS AND METHODS: A cohort of 327 subjects with OLL, confirmed in 1973-1974 during a population-based survey in two Swedish municipalities, was followed through January 2002 via record linkages with nationwide and essentially complete registers. A sample of 80 drawn from the 194 surviving subjects who still resided in the area in 1993-1995 was invited for interview and oral re-examination. RESULTS: At the end of follow-up, one case of oral cancer was detected, while 0.4 were expected. The overall mortality among subjects with OLL was not significantly different from that in the 15,817 OLL-free subjects who participated in the initial population based survey in 1973-1974. The lesion had disappeared in 14 (39%) of 36 re-examined subjects with white OLLs in 1973-1974, and four (11%) had transformed into red types. In the corresponding group of 19 with red forms initially, five (26%) had become lesion free and four (21%) had switched to white types. Although the cohort size does not permit firm conclusions regarding oral cancer risk, the natural course over up to 30 years appears to be benign in the great majority.  相似文献   
45.
46.
Experience in the treatment of 30 cases with gas gangrene from war wounds   总被引:1,自引:0,他引:1  
Z Y Li  X L Wang  X S Wang 《中华外科杂志》1986,24(10):580-1, 637
  相似文献   
47.
When blood flow through the internal and external carotid arteries is completely interrupted by ipsilateral common carotid artery occlusion, the arterial orbital circulation may be more compromised than the brain supply. We studied a pure and extreme example of this situation in a patient who presented with acute orbital infarction, but no cerebral ischemia on clinical, CT and single-photon emission computerized tomography (SPECT) grounds. Ipsilateral blindness corresponded to retinal, choroidal and optic nerve infarction. The pattern of ophthalmoplegia, with relative sparing of adduction, was more compatible with a muscle than a nerve dysfunction, but a reactive dilated pupil, corneal anesthesia, and orbital pain suggested that the intraorbital branches of the ocular motor nerves and ophthalmic division of the trigeminal nerve were not spared. In addition, signs of widespread ocular ischemia were present. Sequential examinations documented the evolution pattern over 1 year. The absence of an orbital collateral supply from the contralateral external carotid and muscular cervical arteries systems, which contrasted with an adequate middle cerebral artery supply via the contralateral internal carotid artery, may explain this isolated and complete form of orbital ischemia due to common carotid artery occlusion.  相似文献   
48.
Delta hepatitis virus infection in China   总被引:1,自引:0,他引:1  
To assess the prevalence, epidemiological features and prognostic implications of hepatitis D (Delta) in Sichuan Province, The People's Republic of China, 649 sera (515 from HBsAg positive patients and 134 from HBsAg negative subjects) were tested by radioimmunoassay (RIA) for antibody to the hepatitis D virus (anti-HD). Forty-seven sera (7.2%) showed some degree of reactivity. Serial dilutions of these sera indicated that prozoning was not responsible for the equivocal results. Thirty-four of the 47 sera were submitted under code to a second laboratory for independent analysis. According to those results anti-HD antibodies were detected in four of these sera. The overall prevalence of anti-HD in the HBsAg positive patients therefore was 0.8% (4/515). On the basis of clinical, biochemical and histological data 427 HBsAg positive sera were further divided into acute Type B hepatitis, chronic Type B hepatitis, healthy carrier state and hepatocellular carcinoma (HCC) subgroups. Two of 65 (3.1%) anti-HD positive sera belonged to the acute Type B hepatitis group; one of 104 (0.9%), the chronic Type B hepatitis group and one of 246 (0.4%), the healthy carrier group. No antibody was detected in sera from 12 HBsAg positive HCC patients. All HBsAg negative patients were negative for anti-HD antibody. The results of this study indicate that despite a high prevalence of hepatitis B virus infection, positive serology for delta virus is uncommon in Sichuan Province, The People's Republic of China.  相似文献   
49.
50.
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