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   4443篇
  免费   262篇
  国内免费   53篇
耳鼻咽喉   69篇
儿科学   51篇
妇产科学   121篇
基础医学   730篇
口腔科学   183篇
临床医学   480篇
内科学   906篇
皮肤病学   58篇
神经病学   317篇
特种医学   293篇
外科学   483篇
综合类   94篇
一般理论   1篇
预防医学   267篇
眼科学   42篇
药学   314篇
中国医学   53篇
肿瘤学   296篇
  2023年   22篇
  2022年   88篇
  2021年   161篇
  2020年   70篇
  2019年   107篇
  2018年   125篇
  2017年   95篇
  2016年   139篇
  2015年   183篇
  2014年   222篇
  2013年   265篇
  2012年   419篇
  2011年   353篇
  2010年   191篇
  2009年   160篇
  2008年   243篇
  2007年   248篇
  2006年   242篇
  2005年   202篇
  2004年   142篇
  2003年   148篇
  2002年   144篇
  2001年   108篇
  2000年   120篇
  1999年   63篇
  1998年   33篇
  1997年   31篇
  1996年   23篇
  1995年   10篇
  1994年   15篇
  1993年   10篇
  1992年   31篇
  1991年   30篇
  1990年   27篇
  1989年   24篇
  1988年   22篇
  1987年   34篇
  1986年   34篇
  1985年   9篇
  1984年   12篇
  1983年   19篇
  1982年   9篇
  1981年   11篇
  1979年   11篇
  1978年   12篇
  1976年   7篇
  1974年   13篇
  1972年   14篇
  1970年   6篇
  1965年   7篇
排序方式: 共有4758条查询结果,搜索用时 0 毫秒
1.
2.
应用国产ELISA试剂盒对157例肝癌、肝硬化病人血清中抗-HCV及HBV-M进行检测,101例肝癌10例抗-HCV阳性,阳性率为9.9%;56例肝硬化6例抗-HCV阳性,阳性率为10.7%;肝癌组抗HCV与HBsAg双阳性率79%(8/101),HBsAg阳性率为723%(73/101),明显高于HCV感染率,说明HBV仍是乙肝流行地区的主要相关因素。14例抗-HCV阳性(包括可疑阳性),肝癌外周血中8例(57.1%)HBsAg阳性,推测HCV可单独作用但更常与HBV形成混合感染参与慢性肝病的癌变过程。  相似文献   
3.
4.
5.
鸡矢藤[Paederia Scandens]提取物0.32mg 加入营养槽内,对小白鼠各期离体子宫的收缩张力、收缩强度、收缩频率以及子宫活动力均有增强作用。与给药前比较,诱导期组分别增加85%、47%、21%和72%;动情期组分别增加70%、77%、41%和41%;非动情组分别增加47%、76%、62%和66%,而且三组间作用无显著性差异。本品还能增强 PGE_2对小白鼠离体子宫的收缩张力、收缩强度、收缩频率以及子宫活动力。与 PGE_2的作用比较,分别增加34%、39%、9%和45%,但收缩频率增加无统计学意义(P>0.05)。上述结果表明,鸡矢藤提取物对小鼠子宫有显著性兴奋作用,而且还能增强PGE_2对小鼠子宫兴奋作用,其机制尚待进一步研究。  相似文献   
6.
7.
A transparent polyvinyl alcohol (PVA) hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water miscible organic solvent by cooling. The physical properties were evaluated in comparison with commercially available soft contact lens materials, such as polyhydroxyethyl methacrylate (PHEMA) and copolymers of methyl methacrylate (MMA) and N-vinyl pyrrolidone (VP). The PVA hydrogel showed higher tensile strength and elongation at break than the other materials, while it had high water content and oxygen permeability the latter being comparable to those of PMMA/VP copolymers. The protein adsorption of the PVA hydrogel was much less than those of the other materials. The PVA hydrogel soft contact lenses were applied on rabbit eyes for 12 weeks. The influence on the cornea was studied by biomicroscopy, ultrasonic corneal pachymetry and histopathological examination. These examinations revealed no abnormal findings in the cornea. These results suggest that the PVA hydrogel may be promising as a new soft contact lens material.  相似文献   
8.
The hypo-osmotic swelling test (HOST or HOS test) usually takes into consideration the total HOS response value with no emphasis either on the value of the response subtypes or the response evaluation time. This study investigated the time course of HOS responses and analysed their physiological relevance. Raw semen spermatozoa and Percoll washed spermatozoa were used in the experiment. The morphological changes in the sperm tail were monitored by incubating the spermatozoa in the hypo- osmotic solution for 16 different time periods. The HOS reactive spermatozoa and the type of HOS reaction (swelling subtypes) of the samples subjected to different duration of treatment were identified under a phase contrast microscope. Also the fate of individual spermatozoa in a hypo-osmotic environment were monitored for 30 min. In spermatozoa exposed to a hypo-osmotic solution, the motility lasted usually less than 2 min and motility characteristics were uniquely different from that of the spermatozoa under iso-osmotic conditions. The HOS response development was permanent but the motility loss due to hypo-osmotic shock was reversible up to 1 min of incubation. There was an indication of ordered transition among the HOS swelling subtypes apparently initiating with subtype b destined to c, d, e, f and g. Further, the subtypes a and g showed gradual decrease and increase, respectively, while subtype b showed abrupt initial increase and then gradual decrease. Transition from b to g could be direct or via one or more than one subtypes. Ultrastructure based analysis indicated that HOS response subtypes are the apparent reflection of the differences in the cytoskeletal assembly of the sperm tail and thus may be identifying different physiological variants in the sperm population. These results indicate that shorter incubation is essential to document the kinetics of various HOS responses but the conventional HOS test misses these important HOS features because of lengthy incubation. Since the time course of ordered transition of HOS responses will vary more than the total HOS response in semen of different aetiologies, the importance of HOS response subtypes and response evaluation time should be taken into consideration when applying HOS test.   相似文献   
9.
10.
目的 比较用硝酸甘油和合心爽治疗98例不稳定型心绞痛的疗效。方法 随机分组,分别静滴合心爽和硝酸甘油,以难治性心绞痛、心肌梗塞或缺血性猝死为治疗终点。结果 发展为难治性心绞痛或心肌梗塞病例在合心爽组为5人,硝酸甘油组为11人,发生心肌梗塞者合心爽组3人,硝酸甘油8人,缺血性猝死者合合爽组无,硝酸甘油组1人。结论 静脉用合心爽治疗不稳定型心绞痛疗效优于硝酸甘油(P〈0.001)。  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