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   3816204篇
  免费   326743篇
  国内免费   14135篇
耳鼻咽喉   52591篇
儿科学   120981篇
妇产科学   99599篇
基础医学   590179篇
口腔科学   106713篇
临床医学   351511篇
内科学   681873篇
皮肤病学   97982篇
神经病学   327243篇
特种医学   152324篇
外国民族医学   498篇
外科学   589708篇
综合类   114992篇
现状与发展   58篇
一般理论   2508篇
预防医学   321054篇
眼科学   88969篇
药学   265381篇
  23篇
中国医学   10264篇
肿瘤学   182631篇
  2021年   56430篇
  2020年   37443篇
  2019年   59019篇
  2018年   75153篇
  2017年   58385篇
  2016年   64350篇
  2015年   78182篇
  2014年   113426篇
  2013年   179188篇
  2012年   104474篇
  2011年   105839篇
  2010年   122392篇
  2009年   126889篇
  2008年   92866篇
  2007年   96585篇
  2006年   107211篇
  2005年   102099篇
  2004年   104200篇
  2003年   94466篇
  2002年   84049篇
  2001年   122021篇
  2000年   116020篇
  1999年   112770篇
  1998年   68167篇
  1997年   65431篇
  1996年   63364篇
  1995年   58795篇
  1994年   52782篇
  1993年   49277篇
  1992年   83451篇
  1991年   79872篇
  1990年   76433篇
  1989年   74998篇
  1988年   69766篇
  1987年   68452篇
  1986年   65251篇
  1985年   65123篇
  1984年   56843篇
  1983年   51507篇
  1982年   44939篇
  1981年   42070篇
  1980年   39650篇
  1979年   49175篇
  1978年   41116篇
  1977年   36914篇
  1976年   34212篇
  1975年   32988篇
  1974年   35725篇
  1973年   34380篇
  1972年   31848篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
963.
Summary A case of bilateral congenital pseudarthrosis of the clavicle in a baby boy is described. The patient is fully asymptomatic, and no functional impairment is present. This is probably only the seventh case described of this rare congenital anomaly.  相似文献   
964.
Seventy patients, aged 1–20 years, were seen at Jordan University Hospital with high blood pressure (BP) over a 3-year period. BP values ranged from 140 to 230 mmHg for systolic pressure and from 90 to 130 mmHg for diastolic pressure. Essential hypertension was seen in only 6 patients (8.6%); secondary hypertension (n=64 or 91.4%) was due to renal parenchymal diseases (RPD) in 46 patients (65.7%), reno-vascular lesions in 8 (11.4%), renal transplantation in 5 (7.2%), teenage pregnancy in 4 (5.7%), and phaeochromocytoma in 1 patient (1.4%). The aetiologies of RPD were as follows: end-stage renal disease requiring dialysis in 14 patients, acute glomerulonephritis in 14, idiopathic nephrotic syndrome in 10, chronic renal insufficiency in 5, and polycystic kidney in 3 patients. Surgical cure of hypertension was achieved in 5 of the children with reno-vascular lesions and in the patient with phaeochromocytoma.  相似文献   
965.
No excess of DR*3/4 in Ashkenazi Jewish or Hispanic IDDM patients   总被引:1,自引:0,他引:1  
The gene frequencies, haplotype relative risks, and zygotic assortments of HLA-DR in three ethnically defined samples of insulin-dependent diabetes mellitus (IDDM) patients were determined in a prospective family study. Although DR3 and DR4 were positively associated with IDDM in the probands of 123 northern European, 94 Ashkenazi Jewish, and 49 New York Hispanic families, significant excess of DR*3/4 heterozygotes was observed only among the probands from families of northern European ancestry. There was also a significant decrease in the frequency of Bw62,DR4 haplotypes derived by northern European patients from their mothers compared with their fathers. This difference, together with data reported in the literature, suggests that the expressivity of the susceptible genotype(s) in IDDM patients may be modified by protective maternal effects associated with Bw62,DR4 and probably other DR4 haplotypes. Samples of IDDM patients from populations with high frequencies of these modifiers should have different DR-gene frequencies contributed by fathers and mothers, capable of accounting for the observed Hardy-Weinberg disequilibrium. We postulate that, because the mechanism of action of these modifiers is distinct from that of the susceptibility gene, the difference must be considered in devising strategies for elucidation of the mode of inheritance of the disease and for understanding the molecular nature of the susceptibility.  相似文献   
966.
Summary Intracavitary application of ultrasound was first performed for diagnostic purposes in 1967; since that time, it has been more and more widely used. As far as the gastrointestinal tract is concerned, endoscopically controlled ultrasonic probes provide visualization of the various layers of the intestinal wall. It is therefore possible to describe lesions of the esophagus, stomach, and the rectum with regard to their nature and depth of infiltration. Furthermore, periesophageal and perigastric organs can be visualized. It has become evident that endosonography is particularly important for pretherapeutic staging of tumors of the esophagus, stomach, and rectum. Here prospective comparative studies confirm the superiority of this new diagnostic procedure when compared to the methods available to date.  相似文献   
967.
It has become common practice to rely on fitted estimates ofapparent in vivo metabolic constants (e.g., Vmax and KM) inparameterization of PBPK models. Yet, quantitative estimatesof precision in these fitted parameters are not routinely reported.Such information is needed to assess the reliability of modelpredictions. The purpose of this study was to assess the precisionin estimates of Vmax and KM for chloroform, accounting for boththe statistical uncertainties in parameter estimates from individualdata sets and any additional uncertainty due to differencesin the parameter estimates derived from various experiments.Joint confidence regions for Vmax and KM from each experiment,generated using maximum likelihood techniques, were used toevaluate these questions. Three previously published data setswere considered. Estimates of Vmax and KM obtained from thesedata sets differed more than could be explained as a consequenceof a limited number of observations, measurement error, or stochasticerror. Issues associated with the use of maximum likelihoodtechniques to estimate joint confidence regions, the estimationof metabolic constants from individual experiments within agas uptake study versus the full data set, the degree of overlapin the joint confidence regions for metabolic constants obtainedfrom separate data sets, and the implications for risk assessmentare discussed.  相似文献   
968.
Society often expects mothers and fathers to share equally in the perinatal grief process because the child was a common bond between them. Unfortunately, in perinatal grief, this is not always the case. The mother and the father can experience incongruent grieving and use discordant coping mechanisms. It is important to evaluate these differences to facilitate communication between the distraught parents. Improved communication can in turn facilitate the grieving process.  相似文献   
969.
970.
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