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   2659670篇
  免费   190526篇
  国内免费   8181篇
耳鼻咽喉   36376篇
儿科学   81881篇
妇产科学   70491篇
基础医学   389303篇
口腔科学   73524篇
临床医学   238213篇
内科学   516498篇
皮肤病学   58186篇
神经病学   206500篇
特种医学   99335篇
外国民族医学   574篇
外科学   401559篇
综合类   62316篇
现状与发展   26篇
一般理论   891篇
预防医学   197672篇
眼科学   62526篇
药学   202132篇
  63篇
中国医学   8711篇
肿瘤学   151600篇
  2021年   22725篇
  2019年   22502篇
  2018年   31359篇
  2017年   23871篇
  2016年   26191篇
  2015年   30052篇
  2014年   42063篇
  2013年   60889篇
  2012年   84158篇
  2011年   89112篇
  2010年   53276篇
  2009年   50195篇
  2008年   82741篇
  2007年   88241篇
  2006年   88826篇
  2005年   85460篇
  2004年   81450篇
  2003年   78713篇
  2002年   75955篇
  2001年   129277篇
  2000年   132296篇
  1999年   110881篇
  1998年   31185篇
  1997年   27132篇
  1996年   26924篇
  1995年   25301篇
  1994年   23240篇
  1993年   21785篇
  1992年   83876篇
  1991年   81207篇
  1990年   79049篇
  1989年   76346篇
  1988年   70001篇
  1987年   68490篇
  1986年   63889篇
  1985年   61081篇
  1984年   44682篇
  1983年   37731篇
  1982年   21956篇
  1979年   40197篇
  1978年   28239篇
  1977年   23613篇
  1976年   22132篇
  1975年   23965篇
  1974年   28657篇
  1973年   27148篇
  1972年   25514篇
  1971年   24318篇
  1970年   22369篇
  1969年   21451篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Forty-one multiplex families, from published sources and new data from the National Cancer Institute, segregating for Hodgkin's disease and HLA, have been studied. A reanalysis of these data strongly suggests a recessive mode of inheritance for susceptibility to Hodgkin's disease. The HLA haplotype sharing data between affected relatives demonstrate that approximately 60% of cases in multiplex families are due to an HLA-linked susceptibility gene, the remaining 40% being due to other familial factors. The data clearly support the hypothesis of etiological heterogeneity for Hodgkin's disease, with both HLA-linked and HLA-unlinked factors being responsible. Finally, there is an increased concordance of histological types between affected relatives, but this concordance seems independent of HLA sharing.  相似文献   
992.
Carnitine status in Reye and Reye-like syndromes   总被引:4,自引:0,他引:4  
Fourteen children with the following Reye and Reye-like syndromes were studied to determine each patient's carnitine status: valproate-induced Reye-like attack, ornithine transcarbamylase deficiency, systemic carnitine deficiency, methylmalonic acidemia, and propionic acidemia. Reduced free carnitine and increased serum and urine acylcarnitine levels were found in all patients except for 2 with Reye syndrome, in whom serum creatinine levels were mildly elevated and serum free carnitine levels were not reduced. The renal free carnitine reabsorption rate was reduced in all cases. The free carnitine content of autopsied liver samples were reduced in 2 Reye syndrome patients, 2 OTC deficiency patients, and in a single systemic carnitine deficiency patient. The observed secondary free carnitine deficiency may be a factor in the pathogenesis of Reye and Reye-like syndromes.  相似文献   
993.
The influence of food and water intake on mefenamic acid (N-2,3-xylylanthranilic acid) bioavailability from commercial capsules of high bioavailability was studied in four healthy male volunteers. The drug was administered as a single oral dose of 250 mg, under fasting or nonfasting conditions, and a 4 X 4 Latin-square design was used. Eight blood samples were collected over a 24-h period following drug administration, and the drug plasma concentrations were determined by HPLC. The bioavailability of mefenamic acid from capsules was markedly influenced in the fasting subjects by the water but not by the food intake. A good correlation was found between the bioavailability and amount of water ingested with the drug in the fasting subjects. The area under the plasma concentration-time curve (AUC0-infinity) of mefenamic acid was highest when the capsule was taken with 50 mL of water or immediately after a meal. Increasing the amount of water from 50 to 500 mL in the fasting subjects caused a significant reduction in AUC0-infinity.  相似文献   
994.
Reproductive problems, including congenital malformations, reduced hatching success, and decreased survival of hatchlings, have been observed in colonial-nesting water birds at the San Francisco Bay National Wildlife Refuge (SFBNWR). Twenty-four black-crowned night heron (Nycticorax nycticorax) eggs were collected from SFBNWR in 1983. Twelve of these were collected from separate nests when late-stage embryos were pipping, and an additional egg was randomly collected from each nest for organochlorine analysis. Overt anomalies and skeletal defects were not apparent. Embryonic weights (with partially absorbed yolk sacs removed) were 15% lower (p less than 0.05) in SFBNWR embryos compared to control embryos from the Patuxent Wildlife Research Center (PWRC). Crown-rump length and femur length were shorter for SFBNWR embryos. The geometric mean polychlorinated biphenyl (PCB) concentration in SFBNWR eggs was 4.1 ppm wet weight, with a range of 0.8-52.0 ppm. A negative correlation (r = -0.61; p less than 0.05) existed between embryonic weight and log-transformed PCB residues in whole eggs collected from the same nest at SFBNWR, suggesting a possible impact of PCBs on embryonic growth. A correlation with embryonic weight did not occur for DDE [1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene] residues. Liver microsomal aryl hydrocarbon hydroxylase activity was neither significantly elevated nor correlated with PCB, DDE, or PCB plus DDE log-transformed residues. It is unknown whether the apparent association between PCBs and lower weight is persistent through hatching.  相似文献   
995.
We report a case of vasoactive-agent-induced priapism successfully treated in the emergency department with 10 mg of metaraminol injected into the corpora cavernosa.  相似文献   
996.
997.
In view of the strong evidence supporting the hypothesis that high Expressed Emotion of a key relative contributes to relapse in psychiatric patients, methods used in Expressed Emotion research were applied in an investigation of psychiatric disorder in stroke patients receiving hospital based rehabilitation and support. Patient mood in 37 stroke patients was related to the critical attitude of a key relative. Patient depression may also have been associated with severity of dysphasia, but no link was found between patient mood and the other measures of cognitive or physical deficit used in this study. Psychiatric distress in the key relative had a rather different causal basis. Relatives' psychiatric disorders were associated with physical burden, cognitive deficit, and severity of dysphasia. This study suggests that, when the patient is dependent for self-care, rehabilitation-assisted recovery may alleviate relative distress more than patient distress.  相似文献   
998.
Nursing diagnosis as a critical component of the nursing process provides a common taxonomy to describe problems that nurses can treat and is a convenient, logical way to reference nursing standards. Theory is translated into practice with the use of population-specific prototype care guides and a written orders system. Nurses in leadership are responsible for providing the necessary resources to promote professional growth and facilitate desired change. Recommendations to assist with the implementation of nursing diagnosis are identified in Table 1. The system is dependent on staff nurses' professional commitment to learning and willingness to actively participate in change. Involvement of staff nurses continues to be a critical factor in the improvement of nursing practice.  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