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   63327篇
  免费   6651篇
  国内免费   4805篇
耳鼻咽喉   494篇
儿科学   612篇
妇产科学   598篇
基础医学   7421篇
口腔科学   1215篇
临床医学   8513篇
内科学   9944篇
皮肤病学   614篇
神经病学   3559篇
特种医学   2248篇
外国民族医学   52篇
外科学   6450篇
综合类   11157篇
现状与发展   19篇
一般理论   5篇
预防医学   4414篇
眼科学   1875篇
药学   6888篇
  39篇
中国医学   3443篇
肿瘤学   5223篇
  2024年   267篇
  2023年   1169篇
  2022年   2724篇
  2021年   3427篇
  2020年   2607篇
  2019年   2256篇
  2018年   2258篇
  2017年   2090篇
  2016年   1981篇
  2015年   2979篇
  2014年   3706篇
  2013年   3161篇
  2012年   4895篇
  2011年   5277篇
  2010年   3131篇
  2009年   2422篇
  2008年   3346篇
  2007年   3212篇
  2006年   3161篇
  2005年   3114篇
  2004年   2033篇
  2003年   1976篇
  2002年   1632篇
  2001年   1394篇
  2000年   1432篇
  1999年   1641篇
  1998年   1003篇
  1997年   968篇
  1996年   701篇
  1995年   645篇
  1994年   644篇
  1993年   396篇
  1992年   564篇
  1991年   426篇
  1990年   389篇
  1989年   327篇
  1988年   319篇
  1987年   256篇
  1986年   218篇
  1985年   184篇
  1984年   99篇
  1983年   60篇
  1982年   45篇
  1981年   41篇
  1980年   19篇
  1979年   42篇
  1978年   15篇
  1977年   14篇
  1964年   7篇
  1936年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
kDNA sequence homology of Leishmania donovani isolates from three types of kala-azar foci in China were analyzed by using dot and Southern hybridization with biotin- and 32P-labelled probes. The results revealed kDNA sequence heterogeneity among Leishmania donovani isolates from the three kala-azar foci: sequence homology between isolates of hill and desert foci was higher than that between hill and plain foci isolates. The kDNA hybridization technique was also found to be specific and sensitive for direct identification of Leishmania in animal tissues. In a preliminary survey, kDNA hybridization of cutaneous tissue blots of 71 dogs from endemic regions showed a positive rate of 40.8%, and the rate of double positive cases (touch blot hybridization and bone marrow smear) reached 91.3%. The direct identification of Leishmania in tissues by kDNA hybridization seems to be a useful and convenient method for epidemiological study and clinical diagnosis, especially for species/strain characterization.  相似文献   
42.
选择性髂内动脉结扎与栓塞对盆腔血供的影响   总被引:5,自引:0,他引:5  
目的:旨在探讨选择性髂内动脉结扎与栓塞两种方法对盆腔血供的影响。方法:将两组犬在膀胱上动脉分支以下之髂内动脉分别行结扎与栓塞,对比观察两组膀胱创面出血、盆腔动脉造影及盆腔脏器组织学变化,以确定其盆腔脏器的血供情况。结果:①结扎组膀胱创面出血明显大于栓塞组;②结扎组髂内动脉侧支循环建立时间明显早于且数目多于栓塞组;③两组盆腔脏器均未见缺血坏死。结论:栓塞组阻断髂内动脉侧支循环的数目多于结扎组,故对盆腔血供的影响大于结扎组。避免髂内动脉阻断范围过广可减少盆腔脏器缺血坏死的机会。  相似文献   
43.
Increased myocardial oxygen demand, induced by increased heart rate, may cause myocardial ischemia in the presence of significant coronary artery disease. Alterations in anesthetic depth or technique might put at risk or protect myocardium with compromised blood flow. In 20 dogs with critical left anterior descending coronary artery (LAD) stenosis, atrial pacing rates from 100 to 160 beats/min were achieved, with end-tidal halothane 0.7% (LowH) and 1.1% (HighH), end-tidal isoflurane 1.1% (LowI) and 1.5% (HighI), as well as with continuous fentanyl plus midazolam (FM) infusion anesthesia. Despite significantly different mean arterial and coronary perfusion pressures, rate-pressure product, and left ventricular dP/dtmax, the pacing rate at which systolic shortening decreased below the lower limit of the physiologic response, indicating regional dysfunction, was the same in all investigated anesthesia conditions (LowH: 127 +/- 4 beats/min; HighH: 128 +/- 5 beats/min; LowI: 125 +/- 4 beats/min; HighI: 122 +/- 5 beats/min; FM: 124 +/- 4 beats/min [mean +/- SEM], P greater than 0.05). None of the investigated anesthesia conditions either increased ischemia tolerance or showed a detrimental effect on myocardium with compromised coronary blood flow.  相似文献   
44.
Patient Liu (a male office worker of a company in Beijing), aged 49, paid his first visit on March 10, 2003, with the chief complaint of frequent urination at night for over one year. One year ago, he started to have frequent urination 4-5 times every night, which disturbed his sleep and made him fatigue during the day. Though he tried to drink less water, the above symptoms couldn't be alleviated. The condition was accompanied by such symptoms as listlessness, general lassitude,  相似文献   
45.
46.
红景天胶囊治疗中医虚证100例临床报告   总被引:7,自引:0,他引:7  
采用随机双盲对照法观察了红景天胶囊与绞股蓝胶囊治疗中医虚证160例的临床疗效,结果表明:红景天胶囊治疗明显效率为54%,总有效率为87%,与绞股蓝胶囊对照组比较,其疗效有高度统计学意义。红景天胶囊有确切的升高血红蛋白,高密度脂蛋白,超氧化物歧化酶及皮质醇的作用,同时能过氧化脂质,表明该药物具有益气生血,保护细胞免疫损伤,延缓和防止细胞衰老和作用.  相似文献   
47.
髌骨关节面的应用解剖学研究   总被引:2,自引:0,他引:2  
本文利用150例髌骨(干燥髌骨100例,福尔马林固定膝关节内的髌骨50例)观测了髌骨关节面和关节软骨的形态及其与股骨内外侧髁关节面在屈膝0~135度范围的对应关系。结果发现中间纵嵴向后突起并由下向上逐渐变凸占100%;内侧纵嵴明显突起者占62%,此时其髌骨内侧部关节面与股骨关节面之间的间隙较大;在膝关节屈曲过程申两关节面接触的顺序为髌骨关节面自下而上、股骨内外侧关节面从前向后相对滑动,伸膝时则相反;髌骨关节面的表面积为1019±20(650~1540)mm~2。并讨论了髌骨关节面的解剖学特点及其临床意义。  相似文献   
48.
In vivo multiple-mouse imaging at 1.5 T.   总被引:3,自引:0,他引:3  
A multiple-mouse solenoidal MR coil was developed for in vivo imaging of up to 13 mice simultaneously to screen for tumors on a 1.5 T clinical scanner. For the coil to be effective as a screening tool, it should permit acquisition of MRIs in which orthotopic tumors with diameters >2 mm are detectable in a reasonable period of time (<1 hr magnet time) and their sizes accurately measured. Using a spin echo sequence, we demonstrated that this coil provides sufficient sensitivity for moderately high resolution images (156-176 microm in plane-resolution, 1.5 mm slice thickness). This spatial resolution permitted detection of primary brain tumors in transgenic/knockout mice and orthotopic xenografts. Brain tumor size as measured by MRI was correlated with size measured by histopathology (P < 0.001). Metastatic tumors in the mouse lung were also successfully imaged in a screening setting. The multiple mouse coil is simple in construction and may be implemented without any significant modification to the hardware or software on a clinical scanner.  相似文献   
49.
从2105例胃癌癌旁组织中找出微小腺癌31例(〈0.1cm),观察其组织发生的特征,发现胃腺癌的发生有8种形式:①腺颈部干细胞癌变;②表面上皮癌变;③腺上皮癌变;④肠化生上皮癌变;⑤微腺囊癌变;⑥溃疡边缘上皮癌变;⑦扁平腺瘤癌变;⑧贲门交界处柱状上皮癌变。  相似文献   
50.
“C”型曲线的中耳声学特性改变与鼓室积液的关系   总被引:10,自引:2,他引:8  
对40耳声导抗检查为“C”型曲线患耳进行中耳系统共振频率点测试并进行鼓室穿刺抽液,结果表明:共振频率点低于600Hz,患耳鼓室积液阳性率为82.1%,高于600Hz患者鼓室和液阳性率16.7%,提示依据鼓室导抗图和共振频率点测定可初步判断“C”型曲线患耳鼓室积液的可能.  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