全文获取类型
收费全文 | 796397篇 |
免费 | 82422篇 |
国内免费 | 250篇 |
专业分类
879069篇 |
出版年
2018年 | 7930篇 |
2017年 | 7582篇 |
2016年 | 10631篇 |
2015年 | 13443篇 |
2014年 | 16021篇 |
2013年 | 23123篇 |
2012年 | 25963篇 |
2011年 | 26747篇 |
2010年 | 18268篇 |
2009年 | 16886篇 |
2008年 | 23910篇 |
2007年 | 24877篇 |
2006年 | 23252篇 |
2005年 | 22360篇 |
2004年 | 22141篇 |
2003年 | 21303篇 |
2002年 | 20810篇 |
2001年 | 34733篇 |
2000年 | 34194篇 |
1999年 | 27568篇 |
1998年 | 10176篇 |
1997年 | 10263篇 |
1996年 | 9838篇 |
1995年 | 9057篇 |
1994年 | 8720篇 |
1993年 | 8751篇 |
1992年 | 22333篇 |
1991年 | 21916篇 |
1990年 | 21368篇 |
1989年 | 20812篇 |
1988年 | 19079篇 |
1987年 | 18321篇 |
1986年 | 17091篇 |
1985年 | 16952篇 |
1984年 | 13933篇 |
1983年 | 12181篇 |
1982年 | 9230篇 |
1981年 | 8355篇 |
1980年 | 7753篇 |
1979年 | 12938篇 |
1978年 | 10201篇 |
1977年 | 9191篇 |
1976年 | 8802篇 |
1975年 | 9816篇 |
1974年 | 10484篇 |
1973年 | 10350篇 |
1972年 | 9477篇 |
1971年 | 8456篇 |
1970年 | 7384篇 |
1969年 | 7255篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
E Imbasciati R Gusmano A Edefonti P Zucchelli C Pozzi C Grassi M Della Volpe F Perfumo P Petrone M Picca et al. 《BMJ (Clinical research ed.)》1985,291(6505):1305-1308
In a multicentre, randomised, prospective trial 89 patients (67 children and 22 adults) with the minimal change nephrotic syndrome were treated with three intravenous pulses of methylprednisolone followed by low dose oral prednisone for six months (group given methylprednisolone) or with high dose oral prednisone for four weeks followed by low dose oral prednisone for five months (control group). Five patients in the group given methylprednisolone and one in the control group did not respond initially. The time to response was shorter in children treated with methylprednisolone. No significant differences between the two groups were observed in the number of patients who relapsed or number of relapses per patient per year. Patients given methylprednisolone tended to relapse earlier than patients in the control group. Side effects related to treatment were significantly fewer in the group given methylprednisolone than in the control group. These data suggest that a short course of methylprednisolone pulses followed by low dose oral prednisone is only marginally less effective than a regimen of high dose oral steroids but can improve the ratio of risk to benefit associated with treatment of the minimal change nephrotic syndrome. 相似文献
102.
Monosomy 21: a new case confirmed by in situ hybridization 总被引:4,自引:0,他引:4
M. C. Pellissier N. Philip M. A. Voelckel-Baeteman M. G. Mattei J. F. Mattei 《Human genetics》1987,75(1):95-96
Summary A new case of total monosomy 21 in a newborn is described. The diagnosis was first made using the cytogenetic data; it was then confirmed by the dosage of copper-superoxide dismutase (SOD-1) which showed a 50% decrease. In situ hybridization with a probe previously assigned to chromosome 21 was used to rule out the possibility of a partial monosomy with an unbalanced reciprocal translocation. 相似文献
103.
W.J. Malaisse F. Malaisse-Lagae A. Sener 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,797(2):194-202
1. Because L-asparagine augments insulin release evoked by L-leucine, the metabolism of these two amino acids was investigated in rat pancreatic islets. 2. L-Leucine inhibited the uptake and deamidation of L-asparagine, but failed to exert any obvious primary effect upon the further catabolism of aspartate derived from exogenous asparagine. 3. L-Asparagine augmented the oxidation of L-leucine, and effect possibly attributable to activaion of 2-ketoisocaproate dehydrogenase. 4. The association of L-asparagine and L-leucine exerted a sparing action on the utilization of endogenous amino acids, so that the integrated rate of nutrients oxidation was virtually identical in the sole presence of L-leucine and simultaneous presence of L-asparagine and L-leucine, respectively. 5. It is proposed that the enhancing action of L-asparagine upon insulin release evoked by L-leucine is attributable to an increased generation rate of cytosolic NADPH rather than any increase in nutrients oxidation. 相似文献
104.
105.
A. Španová 《Folia microbiologica》1980,25(4):281-288
Temperature-sensitive (ts) mutations of the G101 phage were isolated after mutagenesis with hydroxylamine. A complementation analysis of 61ts mutants showed that these mutants may be divided into at least 12 complementation groups. Twots mutants probably originated in genes which control lytic functions of the G101 phage. It was shown by three factor crosses
that all of the 12ts mutations tested are localized on that side of the “c” region where the probablecI repressor gene is positioned. Sevents mutations is closely linked to thecI
26 clear marker, three exhibit a closer linkage and two do not exhibit any linkage withcI. All mutations isolated until now can be arrange linearly. According to the present knowledge the preliminary genetic map
of the G101 phage is linear. 相似文献
106.
107.
A. V. Nikolayev Yu. V. Kirichek O. I. Ostrovskaya I. I. Maletina K. I. Petko L. M. Yagupol’skii 《Neurophysiology》1999,31(3):191-193
With the use of a patch-clamp technique in the whole-cell configuration, we studied the effects of pinacidil and its fluorine
derivatives on A-type potassium current (I
A) through the membrane of pyramidal neurons of the rat hippocampus. Hydrogen peroxide (10 mM) exerted no influence on the
rate of inactivation ofI
A; therefore, this current is probably mediated by Shal Kv4.2 potassium channels. Pinacidil demonstrated the properties of
a weakI
A blocker: in the 500 μM concentration it blocked about 45% of the current, while 50 μM of pinacidil fluorine derivatives were
capable of blocking up to 30% ofI
A. The effects of pinacidil and its derivatives showed no dependence on the stimulating potential. A similar pattern of the
effects of pinacidil fluorine derivatives, which are an order of magnitude stronger than those of pinacidil itself, allows
us to suppose that the imine nitrogen of the tested compounds is significantly more involved in the molecular interaction
with the site of an A-type potassium channel than the pyridine nitrogen. 相似文献
108.
109.
110.
HIF-1 expression in healing wounds: HIF-1alpha induction in primary inflammatory cells by TNF-alpha 总被引:12,自引:0,他引:12