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   119396篇
  免费   6931篇
  国内免费   1583篇
耳鼻咽喉   1598篇
儿科学   2986篇
妇产科学   4116篇
基础医学   18366篇
口腔科学   3614篇
临床医学   9350篇
内科学   21698篇
皮肤病学   2439篇
神经病学   8021篇
特种医学   4029篇
外国民族医学   3篇
外科学   16860篇
综合类   5219篇
一般理论   35篇
预防医学   8713篇
眼科学   2818篇
药学   10256篇
中国医学   821篇
肿瘤学   6968篇
  2021年   987篇
  2019年   1052篇
  2018年   1620篇
  2017年   1173篇
  2016年   1202篇
  2015年   1449篇
  2014年   1896篇
  2013年   2459篇
  2012年   3574篇
  2011年   3815篇
  2010年   2295篇
  2009年   2065篇
  2008年   3403篇
  2007年   3641篇
  2006年   3620篇
  2005年   3196篇
  2004年   3007篇
  2003年   2803篇
  2002年   2658篇
  2001年   6758篇
  2000年   6955篇
  1999年   5718篇
  1998年   1838篇
  1997年   1385篇
  1996年   941篇
  1995年   868篇
  1992年   3735篇
  1991年   3814篇
  1990年   3554篇
  1989年   3565篇
  1988年   3434篇
  1987年   3279篇
  1986年   3092篇
  1985年   2970篇
  1984年   2048篇
  1983年   1793篇
  1982年   992篇
  1979年   1916篇
  1978年   1186篇
  1977年   987篇
  1976年   919篇
  1975年   1195篇
  1974年   1360篇
  1973年   1414篇
  1972年   1358篇
  1971年   1248篇
  1970年   1138篇
  1969年   1121篇
  1968年   1024篇
  1967年   898篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
Structure of receptive fields of visually sensitive neurons in areas CA1 and CA3 of the dorsal hippocampus was investigated in alert cats with the brain-stem pretrigeminal section. The receptive field (RF) structure of 76 hippocampal neurons was analyzed by methods of scanning the RF by moving stimuli and mapping all their surface by a stationary flashing spot. According to presented data the neurons were classified into three groups: neurons with homogeneous structure of the RF (54%), with nonhomogeneous (28%) and neurons more sensitive to stimulus motion (18%) than to a stationary flashing light. Experiments have shown that responses of hippocampal neurons are highly specific ones. Thus, 9% of neurons with the nonhomogeneous RF structure have shown specific responses to variation of the contrast and contours of moving stimuli. The presented results show that hippocampal visually driven neurons have well developed mechanism for processing visual sensory information and apparently this quality ensures participation of the limbic system in visually controlled behavior of the animal.  相似文献   
93.
The authors reviewed the radiographic manifestations of 17 cases of parosteal osteosarcoma, with pathologic correlation in 15. There were two types of parosteal osteosarcoma radiologically. The majority of cases were type I with uniformly dense masses which had regular borders. They often adhered to the cortex and showed no evidence of soft-tissue invasion which correlated with low-grade pathologic malignancy and a relatively benign clinical course. Type II involved the bone, soft-tissue and the medullary cavity. These lesions were poorly differentiated and frequently accompanied by metastatic lesions.
  相似文献   
94.
Sodium nucleinate, an officinal preparation (Na PHK), added to the growth medium in concentrations of 10 to 50 micrograms/ml enhanced the growth of hybridoma cells in vitro. Na PHK presence in the cultivation medium in the above concentrations enhanced the specific antibody-producing activity of hybridomas.  相似文献   
95.
The working clothes and individual protective devices recommended by the industrial Rules for the production of ampicillin trihydrate and its medicinal derivatives such as natrium salt ampicillin, do not provide adequate protection of the skin and respiratory mucous from antibiotic contamination. The use of the overalls in combination with the pressurized helmet (designed and produced at the 'Sintez' enterprise) which provided air supply for breathing and, partially, under the overalls, significantly decreased contamination of the body. At the stages of manual handling of the finished products, adequate protection was attained by using the protective paste produced at the 'Altaivitamine' enterprise.  相似文献   
96.
97.
98.
PURPOSE: This study describes the prevalence of probable major depressive disorder (MDD) as well as other depressive disorders (ODD) and severity of depressive symptoms in a national sample of women with spinal cord injury (SCI) and compares them with a case-matched sample of men with SCI. METHODS: A sample of 585 women was drawn and case-matched with men from the SCI Model System National SCI Database according to level/completeness of injury, follow-up year, and age. The outcome measure of depression was the Patient Health Questionnaire. MAIN FINDINGS: Prevalence rates for women were 7.9% for probable MDD and 9.7% for ODD; rates for men were 9.9% and 10.3%, respectively. Logistic regression revealed that women who were divorced or at year 1 follow-up had a higher odds of having probable MDD (odds ratio [OR], 3.4 and 2.9, respectively). Employed women and men had significantly lower odds of probable MDD (OR, 0.274 and 0.358, respectively). Statistically significant differences were not found in gender comparisons for either probable MDD or symptom severity, which also were not associated with injury characteristics. CONCLUSION: The most significant, and unexpected, research finding is the absence of gender differences in probable MDD and symptom severity. Results challenge notions that depression will necessarily follow SCI; that injury characteristics determine the development and severity of depression; and that women experience a greater burden of depression than men. The main clinical implication is that depression screening and referral should be a routine feature of health care for women living with SCI, as well as for their male counterparts. Furthermore, nearly one fourth of women and men reported experiencing some or greater difficulty in daily life and relationships in the absence of probable depressive disorder, warranting monitoring of subsyndromal depression as well.  相似文献   
99.
100.
Advanced age has been associated with a wide range of defects in both the innate and adaptive immune systems including diminished specific antibody responses that increase the risk of invasive pneumococcal disease (IPD) and limit the effectiveness of vaccines. However, the elderly are a heterogeneous group and measures of overall frailty may be a better indicator of disease susceptibility (or vaccine response) than chronological age alone.  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