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   42696篇
  免费   3782篇
  国内免费   84篇
耳鼻咽喉   313篇
儿科学   2046篇
妇产科学   1329篇
基础医学   6023篇
口腔科学   490篇
临床医学   5087篇
内科学   7984篇
皮肤病学   733篇
神经病学   4816篇
特种医学   863篇
外科学   4194篇
综合类   490篇
现状与发展   1篇
一般理论   76篇
预防医学   5698篇
眼科学   681篇
药学   2858篇
中国医学   51篇
肿瘤学   2829篇
  2024年   64篇
  2023年   592篇
  2022年   806篇
  2021年   2009篇
  2020年   1200篇
  2019年   1746篇
  2018年   1983篇
  2017年   1334篇
  2016年   1489篇
  2015年   1578篇
  2014年   2059篇
  2013年   2609篇
  2012年   3796篇
  2011年   3682篇
  2010年   1840篇
  2009年   1580篇
  2008年   2473篇
  2007年   2558篇
  2006年   2191篇
  2005年   2042篇
  2004年   1780篇
  2003年   1485篇
  2002年   1357篇
  2001年   322篇
  2000年   273篇
  1999年   333篇
  1998年   307篇
  1997年   185篇
  1996年   182篇
  1995年   159篇
  1994年   157篇
  1993年   134篇
  1992年   181篇
  1991年   160篇
  1990年   144篇
  1989年   140篇
  1988年   138篇
  1987年   120篇
  1986年   122篇
  1985年   108篇
  1984年   87篇
  1983年   68篇
  1982年   59篇
  1981年   52篇
  1980年   63篇
  1979年   68篇
  1978年   61篇
  1973年   46篇
  1972年   50篇
  1971年   53篇
排序方式: 共有10000条查询结果,搜索用时 515 毫秒
91.
In the last century, both the health and life expectancy of Americans improved dramatically. These gains were primarily the result of advances in public health. But the approaches used may not be adequate to achieve the next level of improvements in health. Because health exists in the context of social, environmental, community, religious, political, and other spheres, ecological approaches that incorporate behavioral and social science theory and methodologies may provide the best avenue for advancing health in the 21st century. In 1999, the New York City Department of Health (NYCDOH) undertook the task of integrating behavioral and social science into its public health practice. The experience serves as a case study on the integration process at a public health agency.  相似文献   
92.
PURPOSE: Perillyl alcohol (POH) displays preventive and therapeutic activity against a wide variety of tumor models, and it has been suggested that this might be associated with the ability of POH to interfere with Ras prenylation. POH also selectively induces G(1) arrest and apoptosis in Bcr/Abl-transformed hematopoietic cells. Because signaling through Ras is necessary for Bcr/Abl transformation, we examined whether POH induces its anti-leukemia effect by inhibiting Ras signaling. EXPERIMENTAL DESIGN: The ability of POH to inhibit posttranslational farnesylation and signaling from Ras as well as signaling through the Raf-Mek-Erk cascade was examined in Bcr/Abl-transformed and mock-transformed cells and related to the anti-leukemia effect of POH. RESULTS: POH does not affect Ras prenylation or Ras activity, but it blocks signaling downstream of Ras by reversing the state of activation of the Erk kinase, Mek. POH affects Mek activity only when it is added to intact cells. Treatment of either cell lysates or of purified Mek with POH has no effect on Mek activity. Inhibition of the Mek-Erk pathway seems to be related to the POH anti-leukemia effect for the following reasons: (a) the concentration of POH needed to block the Erk pathway, as well the kinetics with which POH inhibits this signaling cascade, both correlate with the anti-leukemia effect of POH; (b) both U0126 (a specific Mek inhibitor) and POH induce similar anti-leukemia effects; and (c) mock-transformed hematopoietic cells are simultaneously resistant to POH anti-leukemia effects and inhibition of the Mek-Erk pathway. CONCLUSION: Blocking Mek is sufficient to induce growth arrest and apoptosis in Bcr/Abl-transformed cells; therefore, POH represents a novel small molecule inhibitor of Mek that might be effective for treating Bcr/Abl leukemias.  相似文献   
93.
94.
OBJECTIVES: Despite longstanding national guidelines, many children with asthma do not receive annual influenza vaccinations. Information from Medicaid-administrative claims data was integrated into the Michigan Care Improvement Registry (MCIR) to prompt providers regarding influenza vaccination among children with high-risk conditions such as asthma. The attitudes of pediatric primary care providers regarding the implementation of this system were assessed. METHODS: A survey was sent in February 2006 to office-based general pediatricians (n = 300) and family physicians (n = 300) in Michigan. The survey focused on influenza vaccination during the 2005-2006 influenza season and attitudes regarding a reminder system for providers using the MCIR. RESULTS: Overall response rate was 67 percent. MCIR participation was high (91%) among respondents, and most (83%) had MCIR information available to them prior to visits with pediatric patients. Most physicians (75%) considered the MCIR high-risk indicator for influenza vaccination a feature that they would find helpful. Some respondents reported concerns that the reminder system is limited to Medicaid patients only (44%) and regarding the completeness of Medicaid data to identify children with asthma (24%). CONCLUSIONS: Physicians have a positive overall view of a statewide registry-based automated reminder system to assist in identifying children with asthma for influenza vaccination, albeit with specific areas of concern.  相似文献   
95.
96.
97.
We measured serum alkaline phosphatase isoenzymes and osteocalcin levels in 40 healthy women at 4-week intervals throughout uncomplicated pregnancies and 6 weeks after delivery in 17 women. Serum bone alkaline phosphatase was significantly higher in the third trimester than in early pregnancy (P less than 0.001), and this elevation was still apparent at the end of the puerperium, suggesting increased bone turnover. Serum osteocalcin was not detected (less than 0.2 micrograms/L) after the first trimester in the majority of women, and it reappeared within 48 h after delivery. The disappearance of osteocalcin after the first trimester and its rapid reappearance after delivery suggest placental clearance of this peptide. We conclude that serum osteocalcin measurements cannot be used as a marker of bone metabolism during pregnancy.  相似文献   
98.
99.
A system proposed by Wing and coworkers for subtyping autistic individuals on the basis of social interaction is examined in 78 autistic, 39 atypical, and 32 nonautistic, developmentally disordered individuals. Clinical ratings and questionnaire data based on the proposed subtypology were employed. Clinicians were able to reliably group both autistic and nonautistic cases into the three subtypes; these subtypes were strongly related to IQ. Issues relating to the validity and utility of this subtypology are discussed.  相似文献   
100.
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