全文获取类型
收费全文 | 407336篇 |
免费 | 46336篇 |
国内免费 | 176篇 |
专业分类
453848篇 |
出版年
2018年 | 3512篇 |
2017年 | 3503篇 |
2016年 | 4710篇 |
2015年 | 6273篇 |
2014年 | 7290篇 |
2013年 | 10888篇 |
2012年 | 12177篇 |
2011年 | 12312篇 |
2010年 | 8234篇 |
2009年 | 7687篇 |
2008年 | 11176篇 |
2007年 | 11328篇 |
2006年 | 10892篇 |
2005年 | 10293篇 |
2004年 | 10193篇 |
2003年 | 9890篇 |
2002年 | 9649篇 |
2001年 | 18946篇 |
2000年 | 19144篇 |
1999年 | 15539篇 |
1998年 | 5452篇 |
1997年 | 5722篇 |
1996年 | 5531篇 |
1995年 | 5025篇 |
1994年 | 5125篇 |
1993年 | 5005篇 |
1992年 | 12948篇 |
1991年 | 12366篇 |
1990年 | 12300篇 |
1989年 | 12263篇 |
1988年 | 11162篇 |
1987年 | 10612篇 |
1986年 | 9847篇 |
1985年 | 9884篇 |
1984年 | 8031篇 |
1983年 | 6976篇 |
1982年 | 5313篇 |
1981年 | 4688篇 |
1980年 | 4574篇 |
1979年 | 7683篇 |
1978年 | 5941篇 |
1977年 | 5318篇 |
1976年 | 5135篇 |
1975年 | 5547篇 |
1974年 | 5797篇 |
1973年 | 5715篇 |
1972年 | 5182篇 |
1971年 | 4575篇 |
1970年 | 4058篇 |
1969年 | 3739篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
P J McLeod 《CMAJ》1987,136(7):709-712
Twelve Canadian medical schools that had an organized faculty development program were surveyed to evaluate the extent to which such programs were used and to estimate their effectiveness. Common practices included sabbaticals and programs designed to improve instructional skills. The main problems included underfunding, poor participation and inadequate instructor evaluation. 相似文献
972.
The myeloarchitectonics of the specific human fields 40, 39, 37c, 37b of neocortex and also fields 17 and 19 which are the cortex end of visual analyzer has been studied with the help of neurohistological and quantitative methods. According to the character of the fibrous bundles, their diameter, the quantity of the fibrous in them and the diameter of the fibrous gradual changes from field 17 to field 19 and further to field 39 have been shown. It is an evidence of the succession between phylogenetically older and younger fields of the cortex. The peculiarities of the field quantitative myeloarchitectonics differing in the function and genesis are marked by heterochronous growth of these fields square in the process of evolution. 相似文献
973.
A simplified method of manual calculation for inbreeding coefficient (and/or relationship) from complicated pedigree tables presented in a nongraphic mode is offered. The method is based on the use of positional dual codes of ancestors in which all genealogical links of the proband are reflected. 相似文献
974.
M T Hsieh H C Chen P H Hsu T Shibuya 《Proceedings of the National Science Council, Republic of China. Part B, Life sciences》1986,10(1):43-48
Previously, it was found that the ancient Chinese remedy of Suanzaorentang could be a promising anxiolytic drug (Chen and Hsieh, 1985a, Chen and Hsieh, 1985b). To understand the mechanism of the action of Suanzaorentang, the effects of Suanzaorentang on behavior changes and central monoamines and their metabolites were studied in rats. It was found that Suanzaorentang significantly (1) prolonged the period from the onset of clonic to tonic convulsions induced by pentylenetetrazol or picrotoxin, (2) prolonged the sleep duration induced by hexobarbital, (3) reduced locomotor activity, (4) enhanced the hypomotility induced by alpha-MT, (5) reduced the locomotor stimulation produced by levodopa plus benserazide, and (6) reduced central HVA, VMA, and 5-HIAA, but had no significant effects on central DA, NA, and 5-HT. These facts implied that Suanzaorentang decreased the turnover rate of central monoamines and central catecholaminergic activity. 相似文献
975.
Assignment of the human homologue of the mouse t-complex gene TCTE3 to human chromosome 6q27. 总被引:1,自引:0,他引:1
The gene TCTE3 from the mouse t-complex region is expressed specifically in testicular germ cells. It maps in the central subregion of the t-complex on mouse chromosome 17 containing loci involved in transmission ratio distortion and male sterility. In this study, somatic cell hybrid lines have been used to map the human homologue, TCTE3, to the long arm of chromosome 6. CISS hybridization with the human lambda clone h117 refined this chromosome assignment to the very distal position of chromosome 6q27, thus providing further evidence that loci from the t-complex of mouse chromosome 17 can map to opposite arms of human chromosome 6. 相似文献
976.
977.
The kainate (KA) and the quisqualate (QUIS) receptors that activate cation channels in the central nervous system have previously been defined as two of the major glutamate receptor types. In amphibian brain, an exceptionally rich source of these sites, they can be coextracted by octylglucoside and shown to behave as one entity in all analyses made in solution. When partly purified by lectin affinity, ion-exchange chromatography or by sucrose gradient centrifugation, the two activities comigrate in a 1:1 ratio. When the QUIS component is bound to an immobilized specific QUIS agonist, the KA component is extracted in parallel with it. There are equivalent numbers of the QUIS and KA sites and the two sites show a single affinity series for the binding of glutamatergic agonists. We deduce that KA or QUIS select different conformations of a single KA/QUIS receptor binding site, leading thus to the different channel-opening events that have been reported for these two agonists. 相似文献
978.
E Gluckman J Lotsberg A Devergie X M Zhao R Melo M Gomez-Morales M C Mazeron Y Pérol 《Revue fran?aise de transfusion et immuno-hématologie》1984,27(3):391-396
In a double-bind controlled study, oral Acyclovir has been compared to a placebo in a series of 39 consecutive patients undergoing bone marrow transplantation. A dose of 200 mg was given every 6 h from day 8 to day 35 after transplantation. Pharmacokinetic studies have shown the good absorption of the drug despite intestinal damage related to chemoradiotherapy or gut graft-versus-host disease (GVHD), there was no sign of toxicity. The protection against herpes simplex virus (HSV) infection was complete in the treated group when compared to the control group even in patients with high anti-HSV antibody titres. The same protection was observed against cytomegalovirus (CMV) infection. The incidence of HSV and CMV was the same in both groups after treatment ended. This study confirms the efficacy of Acyclovir against HSV infection and possibly against CMV infection when it is given prophylactically after bone marrow transplantation. 相似文献
979.
980.
Ten hypothyroid patients with Hashimoto''s thyroiditis were treated with methimazole 30 mg in addition to thyroxine 0.15 mg daily. Another 10 hypothyroid patients with Hashimoto''s thyroiditis were given thyroxine 0.15 mg alone. After 22 weeks of treatment significant decreases in thyroid microsomal autoantibody titres were observed in both groups (p less than 0.01). There was no difference in the mean change in titre between the two groups. When the patients treated with methimazole were subsequently given thyroxine 0.15 mg alone for a further 22 weeks no additional change in titre was observed. The data suggest that thyroxine, by normalising serum thyroid stimulating hormone concentrations, may reduce the autoantigenic properties of the thyrocytes with a subsequent decrease in autoantibody titres. 相似文献