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   90585篇
  免费   8918篇
  国内免费   7359篇
耳鼻咽喉   655篇
儿科学   857篇
妇产科学   995篇
基础医学   10790篇
口腔科学   1665篇
临床医学   13132篇
内科学   13271篇
皮肤病学   728篇
神经病学   5319篇
特种医学   3190篇
外国民族医学   56篇
外科学   8384篇
综合类   15564篇
现状与发展   22篇
一般理论   13篇
预防医学   5877篇
眼科学   3023篇
药学   9345篇
  102篇
中国医学   5901篇
肿瘤学   7973篇
  2024年   314篇
  2023年   1524篇
  2022年   4294篇
  2021年   5191篇
  2020年   3946篇
  2019年   3216篇
  2018年   3431篇
  2017年   2889篇
  2016年   2841篇
  2015年   4323篇
  2014年   5311篇
  2013年   4525篇
  2012年   6669篇
  2011年   7726篇
  2010年   4682篇
  2009年   3692篇
  2008年   4695篇
  2007年   4556篇
  2006年   4728篇
  2005年   4727篇
  2004年   2804篇
  2003年   2702篇
  2002年   2243篇
  2001年   1960篇
  2000年   2076篇
  1999年   2162篇
  1998年   1445篇
  1997年   1369篇
  1996年   1102篇
  1995年   1020篇
  1994年   844篇
  1993年   537篇
  1992年   602篇
  1991年   511篇
  1990年   469篇
  1989年   425篇
  1988年   353篇
  1987年   296篇
  1986年   229篇
  1985年   178篇
  1984年   81篇
  1983年   50篇
  1982年   42篇
  1981年   36篇
  1980年   24篇
  1979年   21篇
  1964年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The hydrogen-isotope exchange reaction (T-for-H exchange reaction) between tritiated water vapor (HTO vapor) and 3-hydroxy-4-methoxybenzoic acid (and it's analog; 4-hydroxy-3-methoxybenzoic acid) were observed at 50 and 70 degrees C in a gas-solid system to reveal the reactivity of a functional group in an aromatic compound having two substituents in the aromatic ring. Further, it was shown that (a) the reactivity of the compounds used in this work follows the Hammett's rule, and (b) the reactivity of trisubstituted aromatic compound could be analyzed by applying the additive property of the Hammett's rule even if the compound contains a substituent at the ortho-position.  相似文献   
102.
关于课堂多媒体教学的思考   总被引:10,自引:1,他引:9  
多媒体教学已成为课堂教学的一种常用手段,多媒体教学应从实际需要出发,以提高教学效果为目标;需要教师掌握多种计算机及多媒体知识技能,科学地进行教学设计;教学过程中应发挥多媒体的优势,注重师生交流。对此本文进行了探讨。  相似文献   
103.
OBJECTIVE: To study the effect of the cervical plexus and the accessory nerve to the function of the trapezius muscle. STUDY DESIGN AND SETTING: Eighteen adult male Sprague-Dawley rats were randomly divided into three groups. The neurotomies were performed in the left sides and the right sides served as within-subject controls. In group A, the accessory nerve was transected. The C2-5 were transected in group B, and both of the accessory nerve and C2-5 were cut in group C. The electrophysiologic, myophysiologic, and histologic changes of the muscles were measured. RESULTS: There were significant differences (P < 0.05) between the three groups in the recovery rates of the transverse area of the muscles. The CMAP recorded from the experimental sides in group B were similar to the control sides. The values of the maximum tension of the tetanus contraction between the two sides showed no differences either (P > 0.05). CONCLUSION: The accessory nerve supplies the most important motor input to the trapezius. Motor innervations of the cervical plexus are not very significant.  相似文献   
104.
Cables, a cyclin-dependent kinase (cdk) interacting protein, has recently been identified and mapped to human chromosome 18q11. Cables appears to be primarily involved in cell cycle regulation and cell proliferation. Overexpression of Cables in Hela and other cell lines inhibits cell proliferation and tumor formation. We hypothesize that loss of Cables expression is associated with ovarian cancer. To test our hypothesis, we examined Cables expression in the four most common subtypes of ovarian carcinomas: serous, endometrioid, mucinous, and clear cell. In addition, mucinous and serous borderline tumors were also included. Loss of Cables expression was observed at high frequency in ovarian serous (11 of 14 cases, 79%) and endometrioid (5 of 10 cases, 50%) carcinomas. In contrast, strong Cables staining was detected in all clear cell carcinomas (10 cases) and mucinous tumors (5 carcinomas and 5 borderline tumors). The majority of serous borderline tumors (11 of 14 cases, 79%) showed positive Cables staining, with the rest showing focal loss of Cables expression. Furthermore, RT-PCR revealed the lack of Cables mRNA in a human ovarian cancer xenograft. No correlation was noted between loss of Cables and histologic grade, tumor stage, and survival. In conclusion, our results indicate that loss of Cables is common in ovarian serous and endometrioid carcinomas and imply that Cables may be involved in the pathogenesis of these two types of ovarian carcinomas.  相似文献   
105.
106.
抗人生长激素免疫血清的制备和鉴定   总被引:1,自引:1,他引:0  
Using small dosage of human growth hormone to immunize rabbit or guinea pig, it is able to induce anti-hGH antibody formation with high titre and high affinity that could be applied to hGH RIA. In the present study five rabbits and three guinea pigs were immunized with 125-200 micrograms and 250-285 micrograms per animal of hGH respectively, followed by boosters of 10-20 or 160-250 micrograms of hGH at 2-4 week intervals for 6 or 3 months. Blood was drown 1-2 weeks before each booster for determination of antibody formation. Antibody titre and affinity were successively observed and specificity of antibody was determined for the final bleeding. It was shown that titres of immune sera from guinea pigs were much higher than those of rabbit immune sera, but vice versa for antibody affinity. This might be due to larger immunogen dose used for guinea pigs than for rabbits. Fourteen different peptide hormones were tested in reference to cross-immunoreactivity to anti-hGH antibody. It could be demonstrated that the major cross-reactive hormones are hFSH and hLH, and hTSH also reacts to rabbit anti-hGH immune sera at a lesser degree. These cross reactivities are obviously owing to the molecular homogeneities between hGH and these hormones especially of their alpha-subunits.  相似文献   
107.
目的评价高透氧性硬性角膜接触镜(RGPCL)矫正控制中低度近视屈光不正的效果。方法采用RGPCL矫正120眼中低度近视性屈光不正,统计矫正后当天、1年时近视屈光度、散光度的变化。结果观察组的近视度和散光度随戴镜时间延长相对稳定。结论RGPCL对中低近视的度数控制有效。  相似文献   
108.
A case of β-thalassemia major with a huge mass of hernatopoictic tissuc firmly attached tothe dura mater was reported This is the first case reported in China.  相似文献   
109.
自1980到1986年,我院泌尿外科对4例单纯右侧肾动脉狭窄(RAS)性和3例双侧RAS性高血压病人进行了治疗。7例右侧 RAS皆进行了自体肾移植治疗,其中3例双侧RAS者采用PTA治疗,全部病人术后8天内血压皆恢复正常,随诊10个月到6年,无复发且都恢复工作。1例17岁女孩,术后2年结婚,又2年生一女孩,母女健在血压维持正常。  相似文献   
110.
[目的]探讨不同起搏模式对病人生存质量(QOL)的影响。[方法]以健康调查问卷(SF一36量表)对112例不同起搏模式病人进行问卷调查,比较3种起搏模式下病人的QOL水平。[结果]除机体疼痛、角色情绪2个维度外其余6个维度(生理功能、角色限制、活力、社会功能、精神健康、总体健康)3种起搏模式间比较差异有统计学意义(P〈0.05)。[结论]应用AAI型、DDD型起搏器的病人生存质量优于VVI型起搏。  相似文献   
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