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   89970篇
  免费   9479篇
  国内免费   6601篇
耳鼻咽喉   912篇
儿科学   790篇
妇产科学   774篇
基础医学   9003篇
口腔科学   1387篇
临床医学   11439篇
内科学   11959篇
皮肤病学   847篇
神经病学   4192篇
特种医学   3659篇
外国民族医学   33篇
外科学   10362篇
综合类   18397篇
现状与发展   20篇
一般理论   8篇
预防医学   6970篇
眼科学   2336篇
药学   9956篇
  96篇
中国医学   6273篇
肿瘤学   6637篇
  2024年   474篇
  2023年   1771篇
  2022年   4334篇
  2021年   5346篇
  2020年   4264篇
  2019年   3215篇
  2018年   3367篇
  2017年   3188篇
  2016年   3014篇
  2015年   4541篇
  2014年   5511篇
  2013年   5492篇
  2012年   7872篇
  2011年   8242篇
  2010年   5908篇
  2009年   4734篇
  2008年   5199篇
  2007年   5086篇
  2006年   4571篇
  2005年   4144篇
  2004年   2684篇
  2003年   2307篇
  2002年   1902篇
  2001年   1480篇
  2000年   1302篇
  1999年   1299篇
  1998年   696篇
  1997年   699篇
  1996年   572篇
  1995年   485篇
  1994年   422篇
  1993年   233篇
  1992年   261篇
  1991年   237篇
  1990年   229篇
  1989年   171篇
  1988年   161篇
  1987年   132篇
  1986年   110篇
  1985年   76篇
  1984年   66篇
  1983年   35篇
  1982年   28篇
  1981年   24篇
  1980年   15篇
  1979年   21篇
  1978年   27篇
  1974年   13篇
  1973年   12篇
  1972年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
本文采用整群抽样的方法,对湖南两地区城乡共2377人(15岁以上)的成瘾物质使用状况进行调查,其中男1179(49.6%)人,女1199(50.4%人),平均年龄男女分别为41.2(SD=17.5)和43.4(SD=18.6)。结果表明,饮酒率男性为57.5%,女性为17.3%,吸烟率男女分别为68.2%和11.7%;饮酒者多集中在每月饮1次左右的人群中(男57.9%,女77.9%),但吸烟者多集中在每日吸20支及以上(男52.4%,女42.9%)的人群中。除解热镇痛剂外,男性各种精神活性物质的使用频率及剂量皆男高于女性,开始使用的年龄及成瘾的年龄男性低于女性;性别、使用频度、最早使用的年龄、婚姻与饮酒、吸烟量关系最为密切。有14人使用过鸦片类物质,4人使用过兴奋剂。作者讨论了我国成瘾物质使用的特点,指出经济水平、社会文化背景等因素与我国社会性成瘾物质的使用有密切关系。  相似文献   
73.
74.
Arsenic is a natural drinking water contaminant that impacts the health of large populations of people throughout the world; however, the mode or mechanism by which arsenic induces cancer is unclear. In a series of in vitro studies, we exposed leukocytes from humans, mice, rats, and guinea pigs to a range of sodium arsenite concentrations to determine whether the lymphocytes from these species showed differential sensitivity to the induction of micronuclei (MN) assessed in cytochalasin B-induced binucleate cells. We also determined the capacity of the leukocytes to methylate arsenic by measuring the production of MMA [monomethylarsinic acid (MMA(V)) and monomethylarsonous acid (MMA(III))] and DMA [dimethylarsinic acid (DMA(V)) and dimethylarsonous acid (DMA(III))]. The results indicate that cells treated for 2 hr at the G(0) stage of the cell cycle with sodium arsenite showed only very small to negligible increases in MN after mitogenic stimulation. Treatment of actively cycling cells produced induction of MN with increasing arsenite concentration, with the human, rat, and mouse lymphocytes being much more sensitive to MN induction than those of the guinea pig. These data gave an excellent fit to a linear model. The leukocytes of all four species, including the guinea pig (a species previously thought not to methylate arsenic), were able to methylate arsenic, but there was no clear correlation between the ability to methylate arsenic and the induction of MN.  相似文献   
75.
Oxygen plays an important role in the cultivation of primary cellsex vivo. In this study, we used hermetically sealed tissue culture well inserts equipped with oxygen electrodes to measure the oxygen utilization of cultured human bone marrow mononuclear cells (BM MNCs). The oxygen uptake rate (OUR) of BM MNCs was determined during a 14-day culture in which both adherent and nonadherent cells were present. Early in the culture, the cells exhibited very low OURs. The specific OURs (uptake rate per cell) were at approximately 0.005 μmol/106 cells/hr shortly after the initiation of culture. The OUR then increased as the cultures developed. After about 8 to 10 days of cultivation the specific OURs had increased to 0.038±0.006 and 0.025±0.005 μmol/106 cells/hr for adherent and nonadherent cells, respectively, after which no further increase was observed. Based on these oxygen uptake rate data, a mathematical model of oxygen diffusion was formulated and use to investigate issues associated with hematopoietic bioreactor design, including initial cell density, medium depth, reactor configuration, and oxygen partial pressure.In situ OUR measurements confirmed predicted oxygen limitations based on the mathematical model and the experimentally determined OURs. High-density hematopoietic cultures present design challenges in terms of sufficient and uniform delivery of oxygen to an active hematopoietic culture. These challenges can be met by using parallelplate bioreactors with thin liquid layers.  相似文献   
76.
77.
78.
79.
80.
The role of mPer1 in morphine dependence in mice   总被引:6,自引:0,他引:6  
Liu Y  Wang Y  Wan C  Zhou W  Peng T  Liu Y  Wang Z  Li G  Cornelisson G  Halberg F 《Neuroscience》2005,130(2):383-388
Investigations using Drosophila melanogaster have shown that the circadian clock gene period can influence behavioral responses to cocaine, and the mouse homologues, mPer1 and mPer2, modulate cocaine sensitization and reward. In the present study, we applied DNAzyme targeting mPer1 to interfere the expression of mPer1 in CNS in mice and studied the role of mPer1 on morphine dependence. We found that the DNAzyme could attenuate the expression of mPer1 in CNS in mice. Mice treated with DNAzyme and morphine synchronously did not show preference to the morphine-trained side, whereas the control group did. In contrast, mice treated with DNAzyme after morphine showed preference to the morphine-trained side as well as the control group did. These results indicate that drug dependence seems to be influenced at least partially by mPer1, but mPer1 cannot affect morphine dependence that has been formed.  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