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   4327篇
  免费   349篇
  国内免费   13篇
耳鼻咽喉   10篇
儿科学   193篇
妇产科学   46篇
基础医学   409篇
口腔科学   174篇
临床医学   639篇
内科学   747篇
皮肤病学   316篇
神经病学   421篇
特种医学   383篇
外科学   442篇
综合类   120篇
一般理论   3篇
预防医学   265篇
眼科学   23篇
药学   313篇
肿瘤学   185篇
  2023年   20篇
  2022年   22篇
  2021年   58篇
  2020年   56篇
  2019年   70篇
  2018年   85篇
  2017年   73篇
  2016年   71篇
  2015年   76篇
  2014年   96篇
  2013年   140篇
  2012年   170篇
  2011年   208篇
  2010年   174篇
  2009年   119篇
  2008年   180篇
  2007年   187篇
  2006年   176篇
  2005年   160篇
  2004年   152篇
  2003年   145篇
  2002年   148篇
  2001年   125篇
  2000年   119篇
  1999年   132篇
  1998年   132篇
  1997年   99篇
  1996年   100篇
  1995年   81篇
  1994年   73篇
  1993年   85篇
  1992年   82篇
  1991年   76篇
  1990年   74篇
  1989年   101篇
  1988年   85篇
  1987年   80篇
  1986年   74篇
  1985年   83篇
  1984年   61篇
  1983年   40篇
  1982年   36篇
  1981年   33篇
  1980年   47篇
  1979年   25篇
  1978年   32篇
  1977年   35篇
  1976年   34篇
  1975年   29篇
  1973年   11篇
排序方式: 共有4689条查询结果,搜索用时 15 毫秒
11.
In the rabbit isolated distal saphenous artery, the population of postjunctional adrenoceptors is of the alpha 1 variety under normal in vitro experimental conditions, based on the potency order of selective agonists and on the effects of the antagonists prazosin and rauwolscine against responses to UK-14304. Angiotensin II (A II, 0.05 microM) however, without affecting resting baseline tension, markedly enhanced responses to UK-14304, particularly at low concentrations. This previously unseen component of the response to UK-14304 was resistant to prazosin (0.1 microM) but susceptible to rauwolscine (1 microM). A II would therefore appear to have a permissive role for the expression of a quiescent population of postjunctional alpha 2-adrenoceptors in the rabbit distal saphenous artery.  相似文献   
12.
OBJECTIVE: This pilot study's aim was to establish feasibility of a protocol for delayed cord clamping (DCC) versus immediate cord clamping (ICC) at preterm birth and to examine its effects on initial blood pressure and other outcomes. STUDY DESIGN: A randomized controlled trial recruited 32 infants between 24 and 32 weeks. Immediately before delivery, mothers were randomized to ICC (cord clamped at 5 to 10 seconds) or DCC (30- to 45-second delay in cord clamping) groups. RESULTS: Intention-to-treat analyses revealed that the DCC group were more likely to have higher initial mean blood pressures (adjusted OR 3.4) and less likely to be discharged on oxygen (adjusted OR 8.6). DCC group infants had higher initial glucose levels (ICC=36 mg/dl, DCC=73.1 mg/dl; p=0.02). CONCLUSION: The research design is feasible. The immediate benefit of improved blood pressure was confirmed and other findings deserve consideration for further study.  相似文献   
13.
14.
15.
荧光原位杂交技术分析人结肠菌群方法研究   总被引:2,自引:0,他引:2  
建立荧光原位杂交技术分析人体内结肠菌群的方法。取受试者新鲜粪便 ,选用 5种特异性的 16SrRNA寡核苷酸探针 ,检测粪便样本收集后的保存时间、温度 ,离心条件及样本固定液存放时间对杂交计数结果的影响。结果建立最佳实验条件为 :粪便样本收集后应尽快在 4℃下保存 ,放置时间不要超过 12小时即作处理 ;样本的适宜离心条件为 70 0g 2分钟 ;样本用多聚甲醛固定后在 - 80℃下存放时间不要超过 5个月。该方法具有较好的稳定性 ,可以有效地检出个体之间结肠菌群的差异。  相似文献   
16.
17.
18.
19.
While the season-of-birth effect is one of the most consistent epidemiological features of schizophrenia, there is a lack of consistency with respect to the interaction between season of birth and family history of schizophrenia. Apart from family history, measures related to consanguinity can be used as proxy markers of genomic heterogeneity. Thus, these measures may provide an alternate, indirect index of genetic susceptibility. We had the opportunity to explore the interaction between season of birth and measure of consanguinity in well-described genetic isolates in Daghestan, some of which are known for their relatively high prevalence of schizophrenia. Our previous population-genetic study showed Daghestan has an extremely high genetic diversity between the ethnic populations and a low genetic diversity within them. The isolates selected for this study include some with more than 200 and some with less than 100 generations of demographical history since their founding. Based on pedigrees of multiply-affected families, we found that among individuals with schizophrenia, the measure of consanguinity was significantly higher in the parents of those born in winter/spring compared to those born in summer/autumn. Furthermore, compared to summer/autumn born, winter/spring born individuals with schizophrenia had an earlier age-of-onset, and more prominent auditory hallucinations. Our results suggest that the offspring of consanguineous marriages, and thus those with reduced allelic heterogeneity, may be more susceptible to the environmental factor(s) underpinning the season-of-the effect in schizophrenia.  相似文献   
20.
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