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   3226316篇
  免费   248419篇
  国内免费   5626篇
耳鼻咽喉   47231篇
儿科学   102491篇
妇产科学   89428篇
基础医学   459332篇
口腔科学   92875篇
临床医学   289314篇
内科学   626208篇
皮肤病学   66668篇
神经病学   265235篇
特种医学   128156篇
外国民族医学   1170篇
外科学   489788篇
综合类   74136篇
现状与发展   2篇
一般理论   1195篇
预防医学   255014篇
眼科学   75915篇
药学   242872篇
  5篇
中国医学   6005篇
肿瘤学   167321篇
  2018年   31990篇
  2016年   27205篇
  2015年   30914篇
  2014年   44080篇
  2013年   67447篇
  2012年   91321篇
  2011年   96791篇
  2010年   56962篇
  2009年   54332篇
  2008年   92254篇
  2007年   98973篇
  2006年   100117篇
  2005年   97747篇
  2004年   94249篇
  2003年   90930篇
  2002年   89976篇
  2001年   146224篇
  2000年   151103篇
  1999年   128027篇
  1998年   37276篇
  1997年   33582篇
  1996年   33518篇
  1995年   32282篇
  1994年   30364篇
  1993年   28242篇
  1992年   103587篇
  1991年   100792篇
  1990年   98087篇
  1989年   94786篇
  1988年   88083篇
  1987年   86654篇
  1986年   82333篇
  1985年   78836篇
  1984年   59598篇
  1983年   51044篇
  1982年   30952篇
  1981年   27527篇
  1980年   25802篇
  1979年   56259篇
  1978年   39771篇
  1977年   33684篇
  1976年   31852篇
  1975年   34048篇
  1974年   41421篇
  1973年   39471篇
  1972年   37305篇
  1971年   34547篇
  1970年   32440篇
  1969年   30446篇
  1968年   28186篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
A mutant form of ammodytoxin A, a neurotoxic phospholipase A2 from the venom of the long nosed viper Vipera ammodytes ammodytes, was prepared by site-directed mutagenesis, conjugated to a nanogold particle and inoculated into the antero-lateral aspect of one hind limb of female mice. Eight hours later the mice were killed, the soleus muscles of both ipsi- and contra-lateral hind limbs were removed, exposed to a silver enhancing medium and then prepared for transmission electron microscopy. Silver-enhanced particles were subsequently found concentrated in the peri-synaptic area, particularly within the synaptic gutter and the deep synaptic folds, and in many cases had been taken up into the cytoplasm of the terminal boutons of the motor axon. The results suggest that the presynaptic neurotoxicity of snake venom phospholipases A2 involves several components of the neuromuscular apparatus, including intracellular organelles of the motor nerve terminal.  相似文献   
992.
993.
994.
995.
996.
Diverticulosis is a common colonic disease in industrialized societies and its prevalence increases with age. Acute diverticulitis is defined by diverticular and peridiverticular inflammation and infection. For most patients, outpatient therapy is possible and hospitalization is only indicated if the patient is unable to eat, suffers from an acute attack, has complications or if symptoms fail to improve despite adequate outpatient therapy. The treatment of acute uncomplicated diverticulitis usually consists of broad-spectrum antibiotics covering both aerobic and anaerobic bacteria. Antimicrobial therapy is given for 7 to 10 days but the duration of the treatment can be longer if there are complications. If there is no clinical improvement within 2 or 3 days, repeat CT imaging is appropriate, as this may reveal an abscess, phlegmon or fistula, which might necessitate percutaneous drainage or surgery. The published literature does not support the recommendation of any prophylactic diet or medical treatment for reducing the risk of first or recurrent diverticulitis in patients with diverticulosis.  相似文献   
997.
A woman's partner and the characteristics of their partnership can play an important role in the health of her pregnancy. Yet, with the notable exception of intimate partner violence, there has been little previous research addressing the associations between partner- or partnership-related factors and birth outcomes. This analysis tested the hypothesis that risk factors related specifically to partner or partnership characteristics increased the risk for preterm birth. Between 2003 and 2005, a total of 580 preterm cases (20–36 weeks gestational age at delivery) and 633 term controls (≥37 weeks) were selected from women delivering at an obstetric hospital in Lima, Peru. Each woman completed a confidential, structured interview and provided biological specimens within 48 h after delivery. Multivariable logistic regression was used to assess associations between partner and partnership characteristics and preterm birth. After adjustment for behavioral, demographic, and obstetric risk factors, ever having had a partner with a history of drug use (aOR = 1.91, 95% CI 1.22–2.99), ever having had anal sex (aOR = 1.40, 95% CI 1.07–1.84), having a current partner with a history of visiting prostitutes (aOR = 1.69, 95% CI 1.22–2.33), and perceiving one's current partner as a “womanizer” (aOR = 1.34, 95% CI 1.02–1.77) were significantly associated with an elevated risk of preterm birth when tested in separate models. These four factors were then used to create a composite partnership risk score, which showed an increasing dose-response relationship with preterm birth risk (per additional partner risk factor: aOR = 1.31, 95% CI 1.16–1.49). These results highlight the importance of considering a broader set of risk factors for preterm birth, specifically those related to a woman's partner and partnership characteristics. Further research could clarify the specific mechanisms through which these partner and partnership characteristics may increase the risk of preterm birth.  相似文献   
998.
The purpose of this study was to evaluate a single-session peer-led safer sex intervention, based on the Information-Motivation-Behavioral Skills theoretical model, for college students residing in campus residence halls. Participants (N = 108) were assigned to either an hour long control or 5-module intervention session. Compared to the control condition, the intervention increased participants’ information and women’s subjective norms about preventative behavior. Both the control and intervention sessions increased intentions to perform preventative behaviors (e.g., keep condoms available). These preliminary results suggest that this intervention is promising for increasing constructs associated with safer sexual behavior and could easily be implemented by residence hall staff.  相似文献   
999.
1000.
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