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   5218篇
  免费   413篇
  国内免费   24篇
耳鼻咽喉   48篇
儿科学   303篇
妇产科学   99篇
基础医学   631篇
口腔科学   86篇
临床医学   529篇
内科学   963篇
皮肤病学   145篇
神经病学   394篇
特种医学   369篇
外科学   456篇
综合类   138篇
一般理论   3篇
预防医学   753篇
眼科学   88篇
药学   383篇
中国医学   1篇
肿瘤学   266篇
  2021年   52篇
  2020年   49篇
  2019年   61篇
  2018年   74篇
  2017年   66篇
  2016年   86篇
  2015年   74篇
  2014年   110篇
  2013年   172篇
  2012年   213篇
  2011年   262篇
  2010年   133篇
  2009年   152篇
  2008年   198篇
  2007年   243篇
  2006年   230篇
  2005年   262篇
  2004年   211篇
  2003年   209篇
  2002年   186篇
  2001年   171篇
  2000年   168篇
  1999年   161篇
  1998年   86篇
  1997年   75篇
  1996年   80篇
  1995年   60篇
  1994年   81篇
  1993年   62篇
  1992年   108篇
  1991年   124篇
  1990年   84篇
  1989年   119篇
  1988年   103篇
  1987年   97篇
  1986年   124篇
  1985年   104篇
  1984年   81篇
  1983年   69篇
  1982年   41篇
  1981年   52篇
  1980年   27篇
  1979年   50篇
  1978年   44篇
  1977年   36篇
  1976年   38篇
  1975年   29篇
  1974年   28篇
  1973年   35篇
  1972年   51篇
排序方式: 共有5655条查询结果,搜索用时 31 毫秒
1.
2.
Breast elastography has been available for more than 15 years but is not widely incorporated into clinical practice. Many publications report extremely high accuracy for various breast elastographic techniques. However, results in the literature are extremely variable. This variability is most likely due to variations in technique, a relatively steep learning curve, and variability in methods between vendors. This article describes our protocol for performing breast elastography using both strain elastography and shear wave elastography, which produces high sensitivity and specificity. Additionally, we will describe the most commonly known false-positive and false-negative lesions as well as how to detect them.  相似文献   
3.
We previously reported poorer survival among non-Hispanic blacks and Hispanics with idiopathic pulmonary fibrosis (IPF) compared to non-Hispanic whites at our center. In the current study, we hypothesized that these disparities would exist in a nationwide cohort of wait-listed patients with IPF. We performed a retrospective cohort study of 2635 patients with IPF listed for lung transplantation between 1995 and 2003 at 94 transplant centers in the United States. The age-adjusted mortality rate was higher among non-Hispanic blacks [hazard ratio (HR) = 1.24, 95% confidence interval (CI) 1.06-1.45, p = 0.009] and Hispanics (HR = 1.29, 95% CI 1.06-1.56, p = 0.01) compared to non-Hispanic whites. These findings persisted after adjustment for transplantation, medical comorbidities and socioeconomic status. Worse lung function at the time of listing appeared to explain some of these differences (HR for non-Hispanic blacks after adjustment for forced vital capacity percent predicted = 1.16, 95% CI 0.98-1.36, p = 0.09; HR for Hispanics = 1.21, 95% CI 0.99-1.48, p = 0.056). In summary, black and Hispanic patients with IPF have worse survival than whites after listing for lung transplant.  相似文献   
4.
A national conference on organ donation after cardiac death (DCD) was convened to expand the practice of DCD in the continuum of quality end-of-life care. This national conference affirmed the ethical propriety of DCD as not violating the dead donor rule. Further, by new developments not previously reported, the conference resolved controversy regarding the period of circulatory cessation that determines death and allows administration of pre-recovery pharmacologic agents, it established conditions of DCD eligibility, it presented current data regarding the successful transplantation of organs from DCD, it proposed a new framework of data reporting regarding ischemic events, it made specific recommendations to agencies and organizations to remove barriers to DCD, it brought guidance regarding organ allocation and the process of informed consent and it set an action plan to address media issues. When a consensual decision is made to withdraw life support by the attending physician and patient or by the attending physician and a family member or surrogate (particularly in an intensive care unit), a routine opportunity for DCD should be available to honor the deceased donor's wishes in every donor service area (DSA) of the United States.  相似文献   
5.
6.
SUMMARY. Samples from 1828 donations were screened for anti-HBc at seven sites in the UK using kits supplied by 10 manufacturers. Only 10 (0.55%) donations were considered to have true anti-HBc reactivity and these were detected by all 10 kits. Additional markers of HBV infection were found in nine of these 10 donations. Additional reactives were found by all kits, the number ranging from 1 to 43.
In the four more specific kits, the 10 true reactives were clearly distinguished from the 'false reactives' by the strength of the reaction. It is concluded that the reliance on a single ELISA test for anti-HBc diagnosis is unwise. The use of a second test known to be more specific than the screening ELISA is recommended.  相似文献   
7.
The possibility was investigated that specific opioid receptor types might selectively alter the production of isolation-induced ultrasonic vocalizations. Intracisternal injections of mu, delta and kappa opioid receptor agonists were administered to isolated 10-day-old rat pups. The mu receptor agonist [D-Ala2-NMe-Phe4-Gly-ol]-enkephalin (DAMGO) and delta receptor agonist [D-Pen2, D-Pen5]-enkephalin (DPDPE) both reduced the rate of isolation-induced ultrasonic calling in the absence of sedation. The kappa receptor agonist U50,488 had the opposite effect, significantly raising the rate of vocalization. Fourteen-day-old pups, with a larger delta receptor population, showed a greater sensitivity to DPDPE than was seen in the younger animals.  相似文献   
8.
In 2002/2005, separate energy requirement equations were generated by the Institute of Medicine's (IOM) Dietary Reference Intake process for normal weight and overweight/obese children and adolescents. The current paper questions the theoretical rationale of having two sets of equations (based solely on body-weight classification): when body weight is considered, overweight and obese children and adolescents do not seem to differ from their normal weight counterparts in energy expended for basal metabolism or physical activity tasks. However, energy needs for weight maintenance among overweight/obese girls were consistently higher when predicted using the equations for overweight/obese individuals compared with those developed for normal weight individuals. In contrast, among overweight/obese boys, they were consistently lower . Although the differences are within the variability of the estimates, even theoretical support for a higher energy intake (as occurs in girls) seems unwise because of the potential contribution to a higher body mass in children who are already at risk. It is the opinion of the authors that the IOM revisit the use of two separate equations and generate one set that is appropriate for all children and adolescents.  相似文献   
9.
10.
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