全文获取类型
收费全文 | 1080190篇 |
免费 | 104281篇 |
国内免费 | 3577篇 |
专业分类
耳鼻咽喉 | 15166篇 |
儿科学 | 36742篇 |
妇产科学 | 30527篇 |
基础医学 | 146982篇 |
口腔科学 | 32458篇 |
临床医学 | 114184篇 |
内科学 | 214682篇 |
皮肤病学 | 25952篇 |
神经病学 | 89776篇 |
特种医学 | 41447篇 |
外国民族医学 | 305篇 |
外科学 | 165314篇 |
综合类 | 23817篇 |
现状与发展 | 40篇 |
一般理论 | 388篇 |
预防医学 | 89711篇 |
眼科学 | 24539篇 |
药学 | 72579篇 |
3篇 | |
中国医学 | 2034篇 |
肿瘤学 | 61402篇 |
出版年
2021年 | 9161篇 |
2020年 | 9140篇 |
2019年 | 8982篇 |
2018年 | 16718篇 |
2017年 | 14921篇 |
2016年 | 16571篇 |
2015年 | 17841篇 |
2014年 | 23867篇 |
2013年 | 32985篇 |
2012年 | 32076篇 |
2011年 | 33724篇 |
2010年 | 24620篇 |
2009年 | 25703篇 |
2008年 | 31696篇 |
2007年 | 32392篇 |
2006年 | 33958篇 |
2005年 | 31329篇 |
2004年 | 30077篇 |
2003年 | 28668篇 |
2002年 | 27613篇 |
2001年 | 48600篇 |
2000年 | 49053篇 |
1999年 | 41792篇 |
1998年 | 13069篇 |
1997年 | 11825篇 |
1996年 | 11938篇 |
1995年 | 11301篇 |
1994年 | 10057篇 |
1993年 | 9313篇 |
1992年 | 32907篇 |
1991年 | 32012篇 |
1990年 | 31465篇 |
1989年 | 30342篇 |
1988年 | 27614篇 |
1987年 | 27655篇 |
1986年 | 25746篇 |
1985年 | 24865篇 |
1984年 | 18617篇 |
1983年 | 15786篇 |
1982年 | 9485篇 |
1979年 | 16911篇 |
1978年 | 12330篇 |
1977年 | 10412篇 |
1976年 | 9834篇 |
1975年 | 10231篇 |
1974年 | 12377篇 |
1973年 | 11889篇 |
1972年 | 10950篇 |
1971年 | 10151篇 |
1970年 | 9429篇 |
排序方式: 共有10000条查询结果,搜索用时 635 毫秒
981.
982.
Increased lymphocyte beta-adrenergic receptor density in progressive multiple sclerosis is specific for the CD8+, CD28- suppressor cell. 总被引:1,自引:0,他引:1
Beta-adrenergic receptor density on T cells from healthy humans is greatest on suppressor cells (CD8+, CD28-) and the effect of catecholamines, secreted by the sympathetic nervous system, predominates on this subset. The sympathetic skin response, a measure of sympathetic nervous system function, is absent in most patients with chronic progressive multiple sclerosis (MS). We measured beta-adrenergic receptor density on suppressor cells, cytotoxic cells, and monocytes from patients with chronic progressive MS and healthy control subjects. Control receptor density on suppressor cells was 2.8 +/- 0.3 fmol/10(6) cells versus a density of 5.1 +/- 0.7 fmol/10(6) cells for patients. Cytotoxic cell (CD8+, CD28+) receptor density was 1.4 +/- 0.4 fmol/10(6) cells in control subjects and 0.9 +/- 0.3 fmol/10(6) cells in the patients. Monocytes displayed beta-adrenergic receptor densities of 2.6 +/- 0.4 fmol/10(6) cells in normal individuals and 2.7 +/- 0.4 fmol/10(6) cells in the patient group. CD8 lymphocyte beta-adrenergic receptor densities in patients with relapsing-remitting and those with stable MS were not different from control values, yet were significantly less than the values for patients with chronic progressive MS. We find that mononuclear cells from healthy control subjects and patients with chronic progressive MS proliferate in response to 200 units/ml of recombinant human interleukin-2 (IL-2) similarly. However, IL-2 treatment increased beta-adrenergic receptor density on normal mononuclear cells, but failed to increase it on mononuclear cells from patients with chronic progressive MS.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
983.
Artificial dopamine agonists are widely employed for the treatment of idiopathic parkinsonism. Pleuropulmonary disease has previously been reported to occur with the use of bromocriptine and mesulergine. We report similar adverse effects induced by the newer agonists lisuride and cabergoline. All these agents are tetracyclic ergot derivatives. This suggests a causal link between ergot-derived dopamine agonists and pleuropulmonary disease. 相似文献
984.
985.
M C Salinsky B S Oken L Morehead 《Electroencephalography and clinical neurophysiology》1991,79(5):382-392
This study was performed to gain a better understanding of EEG frequency analysis test-retest reliability in normal healthy adults, and to evaluate factors which could influence the measured inter-record differences. Nineteen subjects underwent serial EEG recordings at 5 min and 12-16 week intervals. Records were visually edited using a standardized protocol, and FFT frequency analysis performed on segments of 60, 40, or 20 sec total length. Correlation coefficients for broad band features averaged 0.92 over the 5 min retest interval and 0.84 over the 12-16 week interval. There was essentially no difference between correlation coefficients of absolute and relative power features. Coefficients based on 60 sec records were marginally higher than those of 40 or 20 sec records. On the other hand, test-retest percent differences were typically lower for relative as opposed to absolute power features, and 60 sec records showed consistently lower percent differences than did 40 or particularly 20 sec records. Peak alpha frequency and mean frequency were the most stable EEG features at either interval. Montage had significant effects on test-retest differences at the 12-16 week interval. A significant association between intra-record and inter-record variability could not be demonstrated. 相似文献
986.
A spectrophotometric method has been developed for measurements of myeloperoxidase activity in phagocytes, and conditions of measurements specified. Contribution of mononuclear cells to myeloperoxidase activity was found negligible, the major role here was played by neutrophils and eosinophils. Myeloperoxidase activity was found reduced in the patients with chronic granulomatous disease, agammaglobulinemia, and elevated in hyper-IgE-syndrome; this parameter was unchanged in ataxia telangiectasia and chronic dermatomucosal candidiasis. 相似文献
987.
988.
989.
990.
V A Tutel'ian N A Krinitskaia L I Avren'eva E E Kuz'mina A B Levitskaia L V Kravchenko 《Gigiena i sanitariia》1991,(10):49-51
Study of embryotoxic action of deoxynivalenol in levels of 0.2, 1, 5, 10 mg/kg from 7 to 15 day of rat pregnancy was worked up. The 0.2 mg/kg determined as a maximal acceptable dose without toxic effects. 相似文献