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   3438619篇
  免费   251554篇
  国内免费   6276篇
耳鼻咽喉   50386篇
儿科学   111396篇
妇产科学   99046篇
基础医学   488615篇
口腔科学   103001篇
临床医学   299190篇
内科学   660550篇
皮肤病学   75560篇
神经病学   274432篇
特种医学   134870篇
外国民族医学   1180篇
外科学   526104篇
综合类   81364篇
现状与发展   10篇
一般理论   1162篇
预防医学   258863篇
眼科学   82208篇
药学   260393篇
  8篇
中国医学   6851篇
肿瘤学   181260篇
  2018年   31842篇
  2015年   31762篇
  2014年   44060篇
  2013年   67839篇
  2012年   90798篇
  2011年   96695篇
  2010年   57389篇
  2009年   54443篇
  2008年   92859篇
  2007年   99743篇
  2006年   101106篇
  2005年   98636篇
  2004年   96030篇
  2003年   92691篇
  2002年   91183篇
  2001年   154245篇
  2000年   158863篇
  1999年   135247篇
  1998年   38186篇
  1997年   34320篇
  1996年   33882篇
  1995年   32357篇
  1994年   30441篇
  1993年   28450篇
  1992年   109479篇
  1991年   106833篇
  1990年   104931篇
  1989年   102319篇
  1988年   95242篇
  1987年   93839篇
  1986年   89539篇
  1985年   85847篇
  1984年   64418篇
  1983年   55731篇
  1982年   33137篇
  1981年   29712篇
  1980年   27953篇
  1979年   62012篇
  1978年   43840篇
  1977年   37582篇
  1976年   35017篇
  1975年   38339篇
  1974年   46161篇
  1973年   44593篇
  1972年   42203篇
  1971年   39471篇
  1970年   36916篇
  1969年   35216篇
  1968年   32896篇
  1967年   29475篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
961.
962.
963.
964.
A protein from rat testes that catalyzes the oxidation of ethanolin the presence of NAD+, but not NADP+, has been characterizedenzymatically and compared to that of hepatic alcohol dehydrogenaseobtained from the same animals. The testicular enzyme, likethe hepatic enzyme, has a Km value for ethanol in the 0.5–1.0-mMrange and can utilize other alcohols such as n-propanol, n-butanol,and isobutanol, although the Km values for these other alcoholsare considerably lower (0.03–0.08 mM) that that for ethanol.The testicular enzyme is more heat-labile than is the hepaticenzyme. Finally, the testicular enzyme catalyzes the oxidationof retinol and its retinol dehydrogenase activity is inhibitedby ethanol.  相似文献   
965.
966.
Medicaid families under managed care. Anticipated behavior   总被引:1,自引:0,他引:1  
This study reports the results of a household survey of 495 Medicaid clients eligible under the Aid to Families with Dependent Children program in Monroe County, New York. The purpose of the study has been to examine the views and to anticipate the health care choices/decisions of Medicaid clients prior to their enrollment in a new, county-wide Medicaid-managed care program. The findings indicate significant ethnic differentials among the Medicaid poor, both in the choice of care source and in the reasons offered for that choice. Forty percent of those interviewed would like to change to a new source of care, but less than 13% can actually be expected to change. Private practice arrangements were the preferred source of care, yet distance to such sources appears to represent a major stumbling block to access. This study suggests that the managed-care approach being offered in Monroe County may offer the Medicaid eligibles a new stigma-free way of affiliating with a health care provider. This is being recognized by those surveyed as an important element. The study demonstrates that the choices made by the Medicaid recipients are perfectly rational given the recipients' knowledge of Medicaid and the health care system, and the general conditions in which they find themselves. These findings have important implications for the move of Medicaid programs from the fee-for-service to the managed-care/HMO system.  相似文献   
967.
We describe a case of pathologic jealousy (Othello syndrome) in a patient with Parkinson disease, which abated after discontinuing amantadine. We indicate that early recognition and treatment of the syndrome in this disease may avert physical violence. We also believe that our report further suggests a link between this specific behavioral disorder and dopaminergic activity.  相似文献   
968.
A case of Ullrich disease was presented. The patient was a 3-year-old girl with torticollis, generalized muscle weakness and acroatonia since birth. High-arched palate, protruded calcaneus, and mild contracture of proximal joints were also recognized. Intellectual development was normal. Serum level of CPK was slightly increased. In histological and histochemical examinations of quadriceps femoris muscle, proliferated connective tissue, marked variation in the muscle fiber diameter, and a lot of degenerated and regenerated fibers were recognized. Minimal injury easily causes subcutaneous hemorrhage, but no abnormality was found in the structure of collagen.  相似文献   
969.
Behavioral state-specific changes in human hippocampal theta activity   总被引:1,自引:0,他引:1  
Although there has been extensive examination of the behavioral and physiologic correlates of hippocampal theta activity in animals, the human literature consists of a single case study. We investigated the differential effects of four behavioral states on human hippocampal theta activity in 16 epilepsy surgery patients. Behavioral conditions included resting eyes closed (RC), resting eyes open (RO), eyes open with auditory word activation (AW), and eyes open with visuospatial activation (VS). Hippocampal theta activity decreased during both RO and VS compared to both RC and AW. There were reciprocal changes in delta activity. Comparisons of RO to VS and of RC to AW were nonsignificant. The results demonstrate state-specific changes in human hippocampal theta and are consistent with the animal literature that relates hippocampal theta to sensorimotor integration and forebrain volitional mechanisms.  相似文献   
970.
We have succeeded in recording short and middle latency vestibular evoked responses in human subjects. The head was held rigidly in a special, patented head holder, constructed individually for each subject, which gripped the teeth of the upper jaw. The stimulus consisted of 2/sec steps of angular acceleration impulses produced by a special motor with intensities of about 10,000 degrees/sec 2 and with a rise time of 1-2 msec. The electrical activity was recorded as the potential difference between special forehead and mastoid electrodes having a large, secure contact area with the skin. The activity was digitally filtered and averaged in 2 separate channels by means of a Microshev 2000 evoked response system. The short latency responses, with peaks at about 3.5 msec (forehead positive), 6.0 msec (forehead negative) and 8.4 msec (forehead positive; bandpass: 200-2000 Hz; average of 1024 trials), had amplitudes of about 0.5 microV. The middle latency responses had peaks at about 8.8 msec (forehead positive), 18.8 msec (forehead negative) and 26.8 msec (forehead positive; 30-300 Hz; N = 128 trials), with larger amplitudes (about 15 microV). These responses were consistently recorded in the same subject at different times and were similar in different normal subjects. Strenuous control experiments were conducted in order to ensure that these responses are not artefacts due to the movement of conducting media (head, electrodes and leads) in the electromagnetic field of the motor and are elicited by activation of normal labyrinths.(ABSTRACT TRUNCATED AT 250 WORDS)  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