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   26084篇
  免费   1629篇
  国内免费   81篇
耳鼻咽喉   179篇
儿科学   812篇
妇产科学   622篇
基础医学   3891篇
口腔科学   453篇
临床医学   3733篇
内科学   4867篇
皮肤病学   441篇
神经病学   2709篇
特种医学   610篇
外科学   2100篇
综合类   173篇
一般理论   26篇
预防医学   2997篇
眼科学   445篇
药学   1876篇
  1篇
中国医学   56篇
肿瘤学   1803篇
  2024年   23篇
  2023年   211篇
  2022年   386篇
  2021年   714篇
  2020年   469篇
  2019年   641篇
  2018年   776篇
  2017年   552篇
  2016年   613篇
  2015年   793篇
  2014年   922篇
  2013年   1465篇
  2012年   2038篇
  2011年   2190篇
  2010年   1143篇
  2009年   1064篇
  2008年   1778篇
  2007年   1845篇
  2006年   1784篇
  2005年   1672篇
  2004年   1577篇
  2003年   1453篇
  2002年   1277篇
  2001年   171篇
  2000年   131篇
  1999年   178篇
  1998年   221篇
  1997年   170篇
  1996年   163篇
  1995年   117篇
  1994年   125篇
  1993年   106篇
  1992年   75篇
  1991年   86篇
  1990年   72篇
  1989年   78篇
  1988年   48篇
  1987年   50篇
  1986年   48篇
  1985年   51篇
  1984年   69篇
  1983年   72篇
  1982年   70篇
  1981年   48篇
  1980年   50篇
  1979年   34篇
  1978年   22篇
  1977年   25篇
  1976年   26篇
  1974年   23篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
European Journal of Clinical Microbiology & Infectious Diseases - This study determined the carriage rates and antimicrobial resistance (AMR) genes of enterococci from...  相似文献   
92.
Objective: This study evaluates the effectiveness of a peer counseling program at increasing breastfeeding by participants in the Mississippi Special Supplemental Nutrition Program for Women, Infants and Children (WIC). Methods: Data from the 1989–1993 Pediatric Nutrition Surveillance System were analyzed to compare breastfeeding rates in clinics with and without peer counseling programs. A questionnaire completed by program staff to describe the program in greater detail helped identify characteristics associated with greater success. Results: The incidence of breastfeeding rose from 12.3% to 19.9% in those clinics with peer counseling programs, but only from 9.2% to 10.7% in clinics without a program. Clinics that started a program earlier showed greater changes in breastfeeding incidence. However, the presence of lactation specialists or consultants in the clinic appeared to be more important than the presence of less-trained peer counselors. Peer counselors who spent more than 45 minutes per participant were more effective than those spending less time. Conclusions: The peer counseling program significantly increased the incidence of breastfeeding, particularly in clinics with lactation specialists and consultants. Success can be enhanced by ensuring that peer counselors spend a great deal of time with the participants.  相似文献   
93.
  1. 15-Lipoxygenase (15-LO) has been implicated in the pathogenesis of atherosclerosis because of its localization in lesions and the many biological activities exhibited by its products. To provide further evidence for a role of 15-LO, the effects of PD 146176 on the development of atherosclerosis in cholesterol-fed rabbits were assessed. This novel drug is a specific inhibitor of the enzyme in vitro and lacks significant non specific antioxidant properties.
  2. PD 146176 inhibited rabbit reticulocyte 15-LO through a mixed noncompetitive mode with a Ki of 197 nM. The drug had minimal effects on either copper or 2,2′-azobis(2-amidinopropane)hydrochloride (ABAP) induced oxidation of LDL except at concentrations 2 orders higher than the Ki.
  3. Control New Zealand rabbits were fed a high-fat diet containing 0.25% wt./wt. cholesterol; treated animals received inhibitor in this diet (175 mg kg−1, b.i.d.). Plasma concentrations of inhibitor were similar to the estimated Ki (197 nM). During the 12 week study, there were no significant differences in weight gain, haematocrit, plasma total cholesterol concentrations, or distribution of lipoprotein cholesterol.
  4. The drug plasma concentrations achieved in vivo did not inhibit low-density lipoprotein (LDL) oxidation in vitro. Furthermore, LDL isolated from PD 146176-treated animals was as susceptible as that from controls to oxidation ex vivo by either copper or ABAP.
  5. PD 146176 was very effective in suppressing atherogenesis, especially in the aortic arch where lesion coverage diminished from 15±4 to 0% (P<0.02); esterified cholesterol content was reduced from 2.1±0.7 to 0 μg mg−1 (P<0.02) in this region. Immunostainable lipid-laden macrophages present in aortic intima of control animals were totally absent in the drug-treated group.
  6. Results of these studies are consistent with a role for 15-LO in atherogenesis.
  相似文献   
94.
95.
96.
97.
98.
99.
100.
Summary The relationships of INT2 and ERBB2 amplification and of ERBB2 overexpression in primary breast tumors to prognostic factors, recurrence, and survival have generated considerable controversy. The rationale for this study is that long-term, recurrence-free survival is a more direct criterion for testing the validity of a tumor marker than correlation either with prognostic factors or with short-term recurrence and survival. We examined the association of recurrence with INT2 and ERBB2 amplification and ERBB2 expression by comparing primary breast tumors from patients surviving without recurrence for 8.5 years after diagnosis. the LTS group, to tumors from patients recurring within two years, the RR group. The RR (N = 63) and LTS (N = 61) samples were coded and examined for amplification by Southern blotting and for expression by immunohistochemistry. Comparison between the RR and LTS groups demonstrated that INT2 amplification was associated with a significantly (P = 0.018) higher (5.6-fold) risk of recurrence, an association that remained significant after controlling for lymph node (LN), tumor size (TS), and histograde (HG) status. ERBB2 amplification and expression were not associated with a higher recurrence risk. Survival analyses within the RR group, however, demonstrated significantly shorter survival time among cases with than without ERBB2 amplification (P = 0.018, median survival 16 vs 25 months), or ERBB2 expression (P = 0.019, median survival 15 vs 25 months), but not INT2 amplification. Univariate Cox proportional hazards regression models also demonstrated significantly shorter survival among cases with ERBB2 amplification (P = 0.016) or expression (P = 0.049), that remained significant in multivariate analyses (P = 0.022) for ERBB2 amplification. These results indicate a significant positive association between INT2 amplification and risk for tumor recurrence in the RR as compared to the LTS group. The relationship of ERBB2 amplification or overexpression to patient outcome is more complex. ERBB2 amplification and expression have a significant relationship with shorter survival among patients recurrent within two years, but their occurrence in tumors from women surviving without recurrence for 8.5 years suggests that ERBB2 status is not predictive of shorter survival for all breast cancers.  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