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   2758篇
  免费   266篇
  国内免费   14篇
耳鼻咽喉   24篇
儿科学   158篇
妇产科学   109篇
基础医学   460篇
口腔科学   72篇
临床医学   320篇
内科学   610篇
皮肤病学   59篇
神经病学   143篇
特种医学   111篇
外科学   314篇
综合类   65篇
一般理论   4篇
预防医学   252篇
眼科学   34篇
药学   207篇
肿瘤学   96篇
  2021年   39篇
  2020年   23篇
  2019年   38篇
  2018年   46篇
  2017年   28篇
  2016年   42篇
  2015年   40篇
  2014年   54篇
  2013年   90篇
  2012年   140篇
  2011年   150篇
  2010年   80篇
  2009年   97篇
  2008年   147篇
  2007年   135篇
  2006年   152篇
  2005年   152篇
  2004年   116篇
  2003年   122篇
  2002年   102篇
  2001年   72篇
  2000年   90篇
  1999年   82篇
  1998年   28篇
  1997年   19篇
  1996年   23篇
  1995年   36篇
  1993年   22篇
  1992年   63篇
  1991年   63篇
  1990年   45篇
  1989年   63篇
  1988年   52篇
  1987年   39篇
  1986年   51篇
  1985年   43篇
  1984年   29篇
  1983年   26篇
  1981年   20篇
  1980年   18篇
  1979年   21篇
  1978年   19篇
  1976年   17篇
  1974年   18篇
  1973年   20篇
  1972年   18篇
  1970年   26篇
  1969年   16篇
  1968年   16篇
  1966年   22篇
排序方式: 共有3038条查询结果,搜索用时 15 毫秒
1.
2.
ABSTRACT

Objectives: The present study investigated the relationships of enculturation and depressive symptoms with health risk behavior engagement in Mexican-American college students and examined how these relationships differed by gender. Previous research has noted consistent gender differences in health risk behavior (e.g. alcohol use, substance use, and risky sexual behavior) among Latina/os, and emphasized the role of U.S. acculturation in this difference. Research examining the role of heritage cultural retention (i.e. enculturation), and including the added influence of mental health variables, such as depressive symptoms, is currently lacking. This study sought to address this gap.

Design: A large sample (N?=?677) of Mexican-American college students from four universities (located in New York, California, Florida, and Texas) completed an online questionnaire assessing health risk behaviors and corresponding variables.

Results: We found that males who endorsed more behavioral enculturation and depressive symptoms were more likely to engage in health risk behavior than all others in the sample. Contrary to previous literature, no relationship was found between behavioral enculturation and health risk behavior in females.

Conclusion: The current study found behavioral enculturation to be associated with depressive symptoms, and in turn with health risk behaviors among the males in our sample. Additional research will be needed to identify the mechanism underlying the relationship between enculturation and depressive symptoms as well as between depressive symptoms and risky behavior.  相似文献   
3.
4.
5.
Aim: Human Papillomavirus is one of the most crucial infectious disease in gynecology disease. To assess the efficacy of supplemental zinc treatment in clearance of HPV infection. Methods: Eighty zinc-sufficient women between 21-55 years, with positive HPV DNA testing, and abnormal cervical cytology in Pap test (ASCUS or LISL) were randomly divided to case (n=40) and control group (n=40). Case group received oral tablets of zinc sulfate twice a day for 3 months while control group received no placebo. During follow-up patients underwent repeat HPV DNA test and PAP test and were evaluated for clearance/persistence of HPV infection and regression/progression in the lesion grading. Results: As far as demographics, serum zinc levels and the relevant risk factors for persistence of HPV were concerned, there was no significant difference between two groups, except for the frequency distribution of HR-HPV which was significantly higher in case  group. Zinc treatment for 3 months reduced the risk of persistence of HPV infection and progression from baseline cytology (OR = 0.130) (CI 95% 0.04-0.381; p <0.001) and 0.301 (95% CI 0.777-0.116; p = 0.012), respectively. Age, initial cytology, HPV type, and contraceptive method were not related to persistence of HPV. Serum zinc levels increased in the casr group as a result of oral zinc consumption for 3-month period, though without any statistical significance (p = 0.407). Conclusion: The results of the following study suggested that oral intake of zinc sulfate supplement for 3 months increases the rates of HPV clearance and resolution of pre-existing cervical lesion.  相似文献   
6.
7.
8.
9.
Use of resin-based restorative materials recently has become widely accepted for treatment of endodontically treated teeth. However, some solutions routinely used during endodontic treatment procedures may have an effect on bond strengths of adhesive materials to root canal dentin. The purpose of this in vitro study was to evaluate the effect of various medications on microtensile bond strength to root canal dentin. Fourteen extracted human single-rooted teeth were used. The crowns and the pulp tissues were removed. The root canals were then instrumented and widened to the same size. The teeth were randomly divided into seven groups of two teeth each. The root canal dentin walls of the roots were treated with 5% sodium hypochloride (NaOCI), 3% hydrogen peroxide (H2O2), the combination of H2O2 and NaOCl, or 0.2% chlorhexidine gluconate for 60 s; or calcium hydroxide or formocresol for 24 h. The teeth in control group were irrigated with water. The root canals were obturated using C&B Metabond. After 24 h of storage in distilled water, serial 1-mm-thick cross-sections were cut, and approximately 12 samples were obtained from each group. Microtensile bond strengths to root canal dentin were then measured by using an Instron machine. The data were recorded and expressed as MPa. The results indicated that NaOCI, H2O2, or a combination of NaOCl and H2O2 treatment decreased bond strength to root canal dentin significantly (p < 0.05). The teeth treated with chlorhexidine solution showed the highest bond strength values (p < 0.05). In conclusion, chlorhexidine is an appropriate irrigant solution for root canal treatment before adhesive post core applications.  相似文献   
10.

Objective

The aims of this study were to evaluate the tensile bond strengths between indirect composites and dentin of 3 recently developed self-adhesive resin cements and to determine mode of failure by SEM.

Material and Methods

Exposed dentin surfaces of 70 mandibular third molars were used. Teeth were randomly divided into 7 groups: Group 1 (control group): direct composite resin restoration (Alert) with etch-and-rinse adhesive system (Bond 1 primer/adhesive), Group 2: indirect composite restoration (Estenia) luted with a resin cement (Cement-It) combined with the same etch-and-rinse adhesive, Group 3: direct composite resin restoration with self-etch adhesive system (Nano-Bond), Group 4: indirect composite restoration luted with the resin cement combined with the same self-etch adhesive, Groups 5-7: indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem, Maxcem, and Embrace WetBond, respectively) onto the non-pretreated dentin surfaces. Tensile bond strengths of groups were tested with a universal testing machine at a constant speed of 1 mm/min using a 50 kgf load cell. Results were statistically analyzed by the Student''s t-test. The failure modes of all groups were also evaluated.

Results

The indirect composite restorations luted with the self-adhesive resin cements (groups 5-7) showed better results compared to the other groups (p<0.05). Group 4 showed the weakest bond strength (p>0.05). The surfaces of all debonded specimens showed evidence of both adhesive and cohesive failure.

Conclusion

The new universal self-adhesive resins may be considered an alternative for luting indirect composite restorations onto non-pretreated dentin surfaces.  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