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1.
2.
J J Skehel M D Waterfield J W McCauley K Elder D C Wiley 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1980,288(1029):335-339
The biosynthesis of the haemagglutinin glycoproteins of infectious influenza virus particles involves proteolytic cleavage of the primary translation products and the amino acid sequences at the two sites of processing are presented. In addition, details of the primary structure of the haemagglutinin of A/Japan/305/57 (H2N1) are reported and compared with information available for haemagglutinins of other subtypes. 相似文献
3.
Three experiments were performed to study the influence of challenging incentives on feedback-assisted heart rate reduction for coronary-prone (Type A) and non-coronary-prone (Type B) males. In the first experiment, when subjects were given a competitive instructional set, Type As were significantly more successful relative to Type Bs in reducing their heart rate; with a noncompetitive set, Type Bs were significantly more successful than were Type As. In the second experiment, when told that heart rate reduction was a scarce ability, Type As reduced heart rate significantly better than did Type Bs; when told that heart rate reduction was a common ability, Type Bs achieved significantly greater heart rate reduction than did Type As. In the third experiment, when heart rate reduction was described as being instrumental to time-urgency (i.e., getting more done in less time), Type As reduced heart rate significantly bettern than did Type Bs; when heart rate reduction was described as being instrumental to relaxation, Type Bs were significantly better able to reduce heart rate. In all three studies, the incentives had no effect on heart rate when feedback was not provided. The results are discussed as support for the notion that Type A behavioral pattern characteristics can be exploited to reduce Type A symptoms. Implications for how coronary-prone individuals may be challenged to modify symptoms within the clinical setting are discussed. 相似文献
4.
5.
The effects of lipoxygenase metabolites of arachidonic acid on human myometrial contractility 总被引:4,自引:0,他引:4
The effects of the lipoxygenase products of arachidonic acid, 5- and 12-hydroxyeicosatetraenoic acid (5- and 12-HETE) and leukotriene B4 (LTB4), on the spontaneous contractility of lower uterine segment human myometrial strips obtained prior to labour have been studied in vitro. 5-HETE gave a dose- dependent (10-500ng) increase in both the rate of contractions and overall contractility of myometrial strips while 12-HETE and LTB4 had no effect at the same concentrations. Prostaglandin F2 alpha (50ng) contracted all myometrial strips in a similar pattern to 5-HETE but was approximately 10 times more potent. The effect of 5-HETE may be direct or perhaps indirect via interaction with the cyclo-oxygenase pathway. The findings do not disprove the contention that the onset of parturition may be characterised by a switch in arachidonic acid metabolism in intra-uterine tissues from lipoxygenase to cyclo-oxygenase products. 相似文献
6.
Molecular Forms of Acetylcholinesterase and Butyrylcholinesterase in Human Plasma and Cerebrospinal Fluid 总被引:1,自引:0,他引:1
John R. Atack Elaine K. Perry James R. Bonham Robert H. Perry 《Journal of neurochemistry》1987,48(6):1845-1850
The measurement of cholinesterase activities in either plasma or cerebrospinal fluid (CSF) may ultimately prove to be relevant in the diagnosis of neurological and neuropsychiatric disorders. However, studies to date have examined only total enzyme activities. Therefore in the present study we have examined the distribution of the individual molecular forms of both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in plasma and CSF using sucrose density gradient centrifugation. Although the total activities of AChE were of the same order of magnitude in plasma and CSF, there was a considerable difference (120-500-fold) between total BChE activity in the CSF and the BChE-rich plasma. The analysis of the individual molecular forms revealed that the predominant molecular species of AChE and BChE in the CSF--both lumbar and ventricular--was the G4 form. The G4 form also constituted the majority of the plasma BChE activity and, on average, over half (56%) of the plasma AChE activity. The significance of the AChE and BChE molecular form compositions of both plasma and CSF and their possible relationship to pathological states are discussed. 相似文献
7.
M A Nedelman R C Elder K Tepperman 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1989,191(2):179-186
Gold sodium thiomalate was incubated with one cadmium-sensitive cell line and two cadmium-resistant variants. The resistant lines have been reported to synthesize metallothionein (MT) in response to both cadmium and zinc, whereas the sensitive line does not. All cell lines showed a dose-dependent inhibition of growth as a result of gold sodium thiomalate treatment. However, daily comparisons of cell numbers indicate that the cadmium-resistant lines actually increase in number at the highest gold concentrations, whereas numbers of cells in the nonresistant line decrease. MT biosynthesis was measured by monitoring the incorporation of [35S )cysteine into low molecular weight protein. None of the cells synthesized MT in response to gold. When incubated with both zinc and gold, MT was synthesized by both of the cadmium resistant lines; however, the amount of MT synthesized was reduced in the presence of gold which appears to inhibit the uptake of [35S]cysteine by all the cell lines. Although MT is synthesized in the presence of zinc and gold sodium thiomalate, the MT does not have a significant effect on the ability of these cells to withstand high concentrations of gold. 相似文献
8.
Elaine C. Kellogg Stephen Kolaczkowski Michael R. Wasielewski David M. Tiede 《Photosynthesis research》1989,22(1):47-59
We have measured the extent of flash-induced electron transfer from the bacteriochlorophyll dimer, P, to the bacteriopheophytin in the M-subunit, HM, in reaction centers of Rhodopseudomonas viridis. This has been done by measuring the transient states produced by excitation of reaction centers trapped in the PHL
–HM state at 90 K. Under these conditions the normal forward electron transfer to the bacteriopheophytin in the L-subunit, HL, is blocked and the yield of transient P+HM
– can be estimated with respect to the lifetime of P*. Under these conditions flash induced absorbance decreases of the bacteriochlorophyll dimer 990 nm band suggest that a transient P+ state is formed with a quantum yield of 0.09±0.06 compared to that formed during normal photochemistry. These transient measurements provide an upper limited on the yield of a transient P+ HM
– state. An estimate of 0.09 as the yield of the P+ HM
– state is consistent with all current observations. This estimate and the lifetime of P* suggest that the electron transfer rate from P* to HM, kM, is about 5 × 109 sec–1 (M = 200ps). These measurements suggest that the a branching ratio kL/kM is on the order of 200. The large value of the branching ratio is remarkable in view of the structural symmetry of the reaction center. This measurement should be useful for electron transfer calculations based upon the reaction center structure. 相似文献
9.
Pedro J. N. Silva Richard K. Koehn Walter J. Diehl III Robin P. Ertl Elaine B. Winshell Mauro Santos 《Biochemical genetics》1989,27(7-8):451-467
Four samples of the musselMytilus edulis were taken between 1984 and 1987 from Stony Brook, New York, and used to study the glucose-6-phosphate isomerase (GPI) polymorphism
in this species.In vitro specific activity andin vivo flux measured in the same animals were found to be significantly correlated. A significant effect of GPI genotype on flux
was observed in one of the samples; overall, significant evidence of effect of genotype on enzyme activity was also obtained.
GPI activities of common genotypes tend to deviate less from the population mean than those of rare (frequency less than 5%)
genotypes. This suggests the possibility that rare GPI genotypes are rare as a consequence of having biochemical properties
that deviate from an optimum level and, therefore, having a lower fitness. In support of this hypothesis, we found in one
of our samples that shell length is a concave function of GPI activity with an intermediate optimum activity level.
The financial support provided to P.J.N.S. by the Luso-American Educational Commission (Fulbright Program), the Instituto
Nacional de Investigacao Científica (Portugal), and the Faculdade de Ciências da Universidade de Lisboa during several stages
of this research is gratefully acknowledged. Financial support from the Ministerio de Educatión y Ciencia (Spain) in the form
of a postdoctoral Fulbright/MEC fellowship to M.S. is also gratefully acknowledged. Research was supported by National Science
Foundation Grant BSR-8415060 to R.K.K. This is contribution No. 736 from the Program in Ecology and Evolution, State University
of New York at Stony Brook.
On leave from Departamento de Biologia Vegetal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande C2, Lisboa, Portugal. 相似文献
10.
Acute intermittent porphyria caused by a C→T mutation that produces a stop codon in the porphobilinogen deaminase gene 总被引:5,自引:1,他引:4
G. A. Scobie D. H. Llewellyn A. J. Urquhart S. J. Smyth N. A. Kalsheker P. R. Harrison G. H. Elder 《Human genetics》1990,85(6):631-634
Summary A mutation of the porphobilinogen (PBG) deaminase gene that produces the cross-reacting immunological material (CRIM)-negative type of acute intermittent porphyria (AIP) has been identified in one of 43 unrelated patients with this form of the disorder. The mutation is a CT transition that abolishes a PstI recognition site in exon 9 of the gene and converts a codon for glutamine to a stop codon. 相似文献