全文获取类型
收费全文 | 390886篇 |
免费 | 35173篇 |
国内免费 | 304篇 |
专业分类
426363篇 |
出版年
2018年 | 3951篇 |
2017年 | 3787篇 |
2016年 | 5103篇 |
2015年 | 5458篇 |
2014年 | 6916篇 |
2013年 | 9956篇 |
2012年 | 11075篇 |
2011年 | 12012篇 |
2010年 | 8265篇 |
2009年 | 7417篇 |
2008年 | 10641篇 |
2007年 | 11079篇 |
2006年 | 10498篇 |
2005年 | 9970篇 |
2004年 | 9936篇 |
2003年 | 9625篇 |
2002年 | 9546篇 |
2001年 | 18648篇 |
2000年 | 18870篇 |
1999年 | 14248篇 |
1998年 | 4394篇 |
1997年 | 4533篇 |
1996年 | 4300篇 |
1995年 | 3969篇 |
1994年 | 3828篇 |
1992年 | 11450篇 |
1991年 | 11290篇 |
1990年 | 11171篇 |
1989年 | 10938篇 |
1988年 | 10154篇 |
1987年 | 9587篇 |
1986年 | 8653篇 |
1985年 | 9056篇 |
1984年 | 7267篇 |
1983年 | 6235篇 |
1982年 | 4316篇 |
1981年 | 3952篇 |
1980年 | 3779篇 |
1979年 | 6819篇 |
1978年 | 5247篇 |
1977年 | 4778篇 |
1976年 | 4607篇 |
1975年 | 5331篇 |
1974年 | 5899篇 |
1973年 | 5832篇 |
1972年 | 5302篇 |
1971年 | 4835篇 |
1970年 | 4316篇 |
1969年 | 3999篇 |
1968年 | 3824篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
Aneurysm of the median artery causing recurrent carpal tunnel syndrome and anatomic review 总被引:1,自引:0,他引:1
I R Toranto 《Plastic and reconstructive surgery》1989,84(3):510-512
A patient is presented who had recurrent carpal tunnel syndrome symptoms in his left hand 1 year after having undergone release of the transverse carpal ligament. On exploration, this was found to be due to an aneurysm of a median artery and possibly scarring due to this compression around the branches of the bifurcated median nerve. This represents the first case in the literature to comment on (1) the absence of bilaterality of the anatomic finding and (2) carpal tunnel syndrome relative to median artery aneurysm. With this in mind, a plea is made for careful exploration of the carpal tunnel, maintaining an incision as far to the ulnar side of the median nerve as technically possible with thorough visualization of the contents of the tunnel and any anatomic variance involved. The incidence of the combination of aberrant median artery with high bifurcation of the median nerve is unknown, as is the incidence of aneurysm of the median artery. 相似文献
922.
Iu V Kotelevtsev D D Spitkovski? S N Orlov Iu V Postnov 《Biulleten' eksperimental'no? biologii i meditsiny》1989,108(11):608-609
26 male F2 hybrids between spontaneously hypertensive (SHR) and normotensive control (WKY) rats (SHRxWKY)F2 were segregated according to their c-src genotype into SS and WW homozygous groups, corresponding to SHR or WKY and WS heterozygous group. Na, K cotransport in erythrocytes in the WW group was equal to that of WKY and differs significantly from that of WS and SS groups (the rate of Na, K cotransport in latter groups was close to that of SHR). Ca content of RBC in WW group was equal to that of WKY, lower than that of WS and SS groups which in turn was significantly lower than in SHR, indicating polygenic control of the trait. Authors conclude that the c-src locus itself or some other loci inherited in conjunction with c-src determines both the increase of Na, K cotransport and calcium content in erythrocytes of SHR. 相似文献
923.
The behavioral effects of opiate agonists and antagonists were studied on the female aggression model. Mu-agonist buprenorphine more selectively decreased maternal aggression than kappa-agonist tifluadom. Kappa-agonists (bremazocine, tifluadom) increased passive defence in lactating female rats. Ethopharmacological data shows predominant involvement of brain mu-opiate receptor system in the integrative processes of maternal behavior and maternal aggression in particular. 相似文献
924.
The reaction of leech nervous system after elimination of individual mechanosensory neuron by intracellular Pronase injection were studied. In the motor neurons connected with killed cells at 14-90th days after the operation there were the changes of the resting membrane potential and amplitude of postsynaptic potentials developed by the stimulation of mechanosensory neuron. It is suggested that the leech nervous system serves as the dynamic formation depending on changes of neuronal ensemble structure. 相似文献
925.
E. I. Solntseva 《Neurophysiology》1989,21(2):189-192
A dual-microelectrode voltage clamp technique was used for recording voltage-dependent calcium current (Ica) in unidentified neurons isolated fromHelix pomatia. Neither intracellular injection of cyclic adenosine monophosphate (cAMP; 10 nA, 5 min) nor intracellular application of dibutyril-cAMP (dcAMP; 1 mM, 10–20 min) induced a change in normal Ica or produce a reversible 10–20% reduction in amplitude. Adding S-100 protein fraction antibodies to the external medium led to the onset of calcium-dependent inactivation of Ica, bringing amplitude of Ica down to 15±12% of its initial level. Either cAMP or dcAMP then restored inhibited Ica to 50±11% of its original level. It was found that the effects of cAMP on Ica of intact neurons depend on level of cytoplasmic Ca2+.Institute for Brain Research, All-Union Center for Mental Health Research, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 21, No. 2, pp. 247–252, March–April, 1989. 相似文献
926.
Hemoglobin binding to deglycosylated haptoglobin 总被引:1,自引:0,他引:1
The carbohydrate portion of polymeric haptoglobin was gradually removed by exoglycosidases in order to investigate its role in complex formation between haptoglobin and hemoglobin. Total removal of sialic acid diminished the haptoglobin-hemoglobin complex formation 15%. Removal of about 25% of the galactose residues from asialohaptoglobin, i.e., about 40% of the total weight of the carbohydrate moiety, totally inhibited the ability of haptoglobin to form complex with hemoglobin and react with haptoglobin-specific antibodies. Liberation of further galactose residues resulted in slow precipitation of the protein. Removal of a similar part of the carbohydrate moiety from haptoglobin-hemoglobin complex did not liberate hemoglobin from it, and the complex reacted with haptoglobin antibodies. The combined data indicate that the carbohydrate portion is essential for the functionally active form of polymeric haptoglobin to complex with hemoglobin, but it hardly has any direct role in the binding event, and other factors are responsible for the stability of the complex. 相似文献
927.
Signals of translation initiation of operons of Haemophilus influenzae ribosomal proteins were predicted. This process is regulated by the formation of secondary RNA structures to which one of the proteins encoded in a particular operon binds. In some cases, these structures imitate the region of protein binding to rRNA. Predictions are made by comparing with homologous operons of Escherichia coli and analogous regions of rRNA and by estimating the energy of secondary structure formation. It is shown that this regulatory mechanism occurs: in operons L11, S10, S15, spc, and alpha of H.influenzae and, probably, in operon S15 of Helicobacter pylori, Bacillus subtilis, and Mycoplasma genitalium. 相似文献
928.
929.
930.
A mathematical model of autoimmunity is developed. This model is a system of two nonlinear differential equations, which describe the concentration dynamics of tissue cells and agressive lymphocytes. An analysis of the solutions shows that this model reproduces general behaviour of autoimmune diseases. 相似文献