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   8294篇
  免费   620篇
  国内免费   156篇
耳鼻咽喉   31篇
儿科学   62篇
妇产科学   35篇
基础医学   1212篇
口腔科学   661篇
临床医学   516篇
内科学   1066篇
皮肤病学   1116篇
神经病学   694篇
特种医学   138篇
外科学   651篇
综合类   703篇
现状与发展   1篇
预防医学   327篇
眼科学   646篇
药学   747篇
  7篇
中国医学   268篇
肿瘤学   189篇
  2024年   38篇
  2023年   196篇
  2022年   239篇
  2021年   370篇
  2020年   330篇
  2019年   288篇
  2018年   296篇
  2017年   294篇
  2016年   228篇
  2015年   286篇
  2014年   448篇
  2013年   612篇
  2012年   439篇
  2011年   459篇
  2010年   347篇
  2009年   325篇
  2008年   353篇
  2007年   349篇
  2006年   289篇
  2005年   269篇
  2004年   241篇
  2003年   213篇
  2002年   200篇
  2001年   183篇
  2000年   128篇
  1999年   117篇
  1998年   143篇
  1997年   123篇
  1996年   106篇
  1995年   102篇
  1994年   81篇
  1993年   67篇
  1992年   74篇
  1991年   82篇
  1990年   63篇
  1989年   56篇
  1988年   59篇
  1987年   62篇
  1986年   50篇
  1985年   78篇
  1984年   73篇
  1983年   51篇
  1982年   69篇
  1981年   47篇
  1980年   41篇
  1979年   26篇
  1978年   23篇
  1977年   15篇
  1976年   19篇
  1974年   7篇
排序方式: 共有9070条查询结果,搜索用时 31 毫秒
81.
To gain insights into the composition of the B cell repertoire, we have investigated VH gene family expression associated with individual light chains. For this purpose, we have examined the use of 12 VH gene families in a large collection of hybridomas expressing one of the four lambda light chains [lambda 1 (V1J1), lambda 2 (V2J2 and V x J2) and lambda 3 (V1J3)]. Our results show that the distribution of the VH families is very different from one lambda subtype to another. This suggests that a few substitutions between VL regions are sufficient to generate very different associated repertoires by strong selection mechanisms. Moreover, we assume that the global VH expression pattern is not random but rather composed of many preferential VH/VL associations.  相似文献   
82.
A study is performed of the effect of the phenol antioxidant katavidan on autooxidation of microsomes from rat liver exposed to visible light. It is shown that katavidan in a concentration of 10−3 M inhibits but in concentrations of 10−5–10−7 M stimulates autooxidation of microsomes. No stimulation is observed under conditions of dark incubation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, № 10, pp. 393–394, October, 1994 Presented by I. P. Ashmarin, Member of the Russian Academy of Medical Sciences  相似文献   
83.
BACKGROUND: This study was conducted on human cervical mucus using light microscopy (LM) and scanning electron microscopy (SEM). The objective was the morphological characterization of the different mucus types, with samples taken from the lumen of the cervix and from the different secretory zones of the cervical mucosa. METHODS: A total of 230 samples from 195 women were spread out on slides and air dried. The phenomenon of 'ferning' was observed and assessed in these samples using both LM and SEM. Further samples from the lumen of the cervix and the different secretory crypts were spread out on cover slips and fixed with glutaraldehyde (2.5%) to be studied by SEM. RESULTS: The results show the presence of four different morphological mucus types, namely L, S, P and G, in both types of sample using dried and fixed techniques. CONCLUSIONS: Mucus from the lumen of the cervix appears to be a morphologically heterogeneous entity. It contains different types of secretions, the proportions of which vary throughout the menstrual cycle. The different mucosal types show different types of crystallization, different patterns of ultrastructure (probably related to the arrangement of the glycoprotein network) and are produced in different secretory zones of the crypts in the cervix.  相似文献   
84.
85.
Sensitivity to light and sound following minor head injury   总被引:1,自引:0,他引:1  
9 consecutively referred closed head injury (CHI) patients were assessed for sensitivity to light and sound stimuli, within 7-19 days of injury, on both objective and subjective measures. Patients were matched with controls on age, sex, race, socio-economic status and order of test administration. The mean luminance (1366 lux) tolerated by CHI patients was significantly lower (0.01 level by Student's t-test for related samples) than that tolerated by controls (1783 lux). The mean sound intensity tolerated by CHI patients was also lower (82 db) than for controls (94 db), though this difference was not statistically significant. Subjective ratings of sensitivity made by CHI patients after exposure to intense sound and light stimuli, showed no relationship to objective ratings of tolerance. The results demonstrate an objective basis for complaints of increased sensitivity, at least to light, following CHI. These findings do not support earlier "psychogenic" explanations of post-concussion syndrome (PCS) etiology.  相似文献   
86.
The hyperosmolarity response of the ocular standing potential was recorded in unilateral rhegmatogenous retinal detachment (8 eyes) and in the fellow healthy eye (8 eyes). The hyperosmolarity response was greatly suppressed (M-4 SD: M and SD indicate respectively the mean and the standard deviation in normal subjects) in all affected eyes (p < 0.005), and slightly abnormal in 2 fellow eyes. The L/D ratio was normal in 2 affected eyes and in all fellow eyes. The hyperosmolarity response in the affected eyes was still greatly suppressed 14 months after successful surgical treatment.  相似文献   
87.
目的 调查徐州市直属小学学生近视现状,分析教室光环境及学龄对儿童视力的影响。方法 采用整群抽样方法,运用标准对数视力表对直属小学学生进行视力检测;随机抽取4所学校,使用TES-1332A照度计测定教室光环境;计量资料采用t检验或方差分析;计数资料采用χ2检验,等级资料采用秩和检验分析其统计学差异。结果 2018年徐州市小学生近视检出率总体为49.84%(男生45.81%,女生53.88%),女生高于男生(χ2=52.001,P<0.05),且重度近视检出率更高(Z=7.795,P<0.05)。市直属小学生近视检出率54.18%,县区直属小学46.45%,市区高于县区(χ2=47.247,P<0.05)。不同年级近视发生情况不同,二~六年级近视检出率分别为36.03%,40.5%,48.45%,58.77%,65.4%,高年级近视发生率高于低年级(χ2趋势=384.766,P<0.05),且重度近视高于低年级(χ2=742.673,P<0.05)。各检测小学不同楼层间教室黑板以及桌面照度不同 (F=3.894,P<0.05) ,但均符合国家标准。结论 徐州市直属小学学生近视检出率较高,并随学龄延长而加重,女生更严重;监测学校教室光环境符合要求。改善和保护学生视力除了保障教室光环境合格和定期监测外,应进一步探讨影响学生视力的其他因素,共同促进学生视力健康。  相似文献   
88.
Fluorescence-advanced videodermatoscopy is not a widespread diagnostic technique. Its application in dermatology can facilitate the diagnosis of diseases such as cutaneous larva migrans by enabling us to recognize the precise position of larva in vivo on the skin. Using this noninvasive technique, we detected a case of cutaneous larva migrans in a patient.  相似文献   
89.
目的:研究牙本质神经的分布,为牙本质的感觉机制寻找组织学的基础。方法:用健康、发育成熟、新鲜的离体人恒牙做标本。经过EDTA脱钙制成切片。先行染色,后采用光学显微镜及透射电镜进行观察。结果:发现神经纤维及其末梢分布于钙化本质全层,直至釉牙本质界,近表面神经末特别密集。其末梢在光镜下呈结节状或串珠状。电镜下见该结节是神经微纤维分散到组织中,或两末梢的相互吻合。结论:牙本质神经分布的研究结果为牙本质感觉的神经机制学说找到了组织学的基础。  相似文献   
90.
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