全文获取类型
收费全文 | 1078篇 |
免费 | 28篇 |
国内免费 | 47篇 |
专业分类
1153篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 19篇 |
2020年 | 13篇 |
2019年 | 25篇 |
2018年 | 19篇 |
2017年 | 15篇 |
2016年 | 13篇 |
2015年 | 21篇 |
2014年 | 27篇 |
2013年 | 78篇 |
2012年 | 21篇 |
2011年 | 36篇 |
2010年 | 25篇 |
2009年 | 48篇 |
2008年 | 75篇 |
2007年 | 59篇 |
2006年 | 56篇 |
2005年 | 52篇 |
2004年 | 59篇 |
2003年 | 50篇 |
2002年 | 44篇 |
2001年 | 37篇 |
2000年 | 32篇 |
1999年 | 29篇 |
1998年 | 21篇 |
1997年 | 20篇 |
1996年 | 16篇 |
1995年 | 23篇 |
1994年 | 11篇 |
1993年 | 16篇 |
1992年 | 17篇 |
1991年 | 10篇 |
1990年 | 17篇 |
1989年 | 23篇 |
1988年 | 18篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1972年 | 2篇 |
排序方式: 共有1153条查询结果,搜索用时 0 毫秒
1.
J. L. Wilkens T. Kuramoto 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(7):483-490
The decapod cardiovascular system consists of a single ventricle that pumps blood into seven arteries; previous work has
shown that the outflow distribution patterns of intact animals are variable. In the present study, flow recordings were made
from pairs of arteries in semi-isolated hearts whilst different cardioactive hormones were infused into the heart. Each hormone
(5-hydroxytryptamine, octopamine, dopamine, proctolin and F1) changed the outflow pattern, heart rate and ventricular pressure
in a unique way. The probable sites of hormone action are the cardioarterial valves located at the origin of each artery except
one, the dorsal abdominal. Outflow from the dorsal abdominal is controlled downstream by valves located at the origin of the
segmental lateral arteries. The responses to a particular hormone were sometimes different between the hearts of American
and Japanese lobsters.
Accepted: 11 May 1998 相似文献
2.
Identification of different protein functions facilitates a mechanistic understanding of Japanese encephalitis virus (JEV) infection and opens novel means for drug development. Support vector machines (SVM), useful
for predicting the functional class of distantly related proteins, is employed to ascribe a possible functional class to Japanese encephalitis virus protein. Our study from SVMProt and available JE virus sequences
suggests that structural and nonstructural proteins of JEV genome possibly belong to diverse protein functions, are expected to occur in the life cycle of JE virus. Protein functions common to both structural and
non-structural proteins are iron-binding, metal-binding, lipid-binding, copper-binding, transmembrane, outer membrane, channels/Pores - Pore-forming toxins (proteins and peptides) group of proteins. Non-structural
proteins perform functions like actin binding, zinc-binding, calcium-binding, hydrolases, Carbon-Oxygen Lyases, P-type ATPase, proteins belonging to major facilitator family (MFS), secreting main terminal branch (MTB)
family, phosphotransfer-driven group translocators and ATP-binding cassette (ABC) family group of proteins. Whereas structural proteins besides belonging to same structural group of proteins (capsid, structural, envelope),
they also perform functions like nuclear receptor, antibiotic resistance, RNA-binding, DNA-binding, magnesium-binding, isomerase (intra-molecular), oxidoreductase and participate in type II (general) secretory pathway (IISP). 相似文献
3.
N. Fujii N. Tomaru K. Okuyama T. Koike T. Mikami K. Ueda 《Plant Systematics and Evolution》2002,232(1-2):21-33
CpDNA variation in Japanese beech, Fagus crenata (Fagaceae), was studied in 45 populations distributed throughout the species' range. Two cpDNA regions were sequenced: the
non-coding region between the trnL (UAA) 5′exon and trnF (GAA), and the trnK region (including matK). Thirteen distinct cpDNA haplotypes were recognized and each haplotype was found to be geographically structured. Two major
clades (I and II+III) were revealed in phylogenetic analyses among the haplotypes using F. sylvatica as an outgroup. The haplotypes of Clade I were distributed mainly along the Japan Sea side of the Japanese Archipelago, while
those of Clade II+III occurred chiefly along the Pacific Ocean side. Consequently, the distribution of the two major cpDNA
clades suggests that there were two migration routes in the history of F. crenata; one along the Japan Sea and the other along the Pacific Ocean side of the Japanese Islands.
Received March 19, 2001 Accepted November 22, 2001 相似文献
4.
Summary The retinal proteins opsin,-transducin, S-antigen and interstitial retinol-binding protein (IRBP) are essential for the processes of vision. By use of immunocyto-chemistry we have employed antibodies directed against these photoreceptor proteins in an attempt to identify the photoreceptor systems (retina, pineal and deep brain) of the Japanese quail. Opsin immunostaining was identified within many outer (basal portion) and inner segments of retinal photoreceptor cells and limited numbers of photoreceptor perikarya. Opsin immunostaining was also demonstrated in limited numbers of pinealocytes with all parts of these cells being immunoreactive. These results differ from previous observations. In contrast to the results obtained with the antibody against opsin, S-antigen and-transducin immunostaining was seen throughout the entire outer segments and many photoreceptor perikarya of the retina. In the pineal organ immunostaining was seen in numerous pinealocytes in all follicles. These results conform to previous findings in birds. In addition, IRBP has been demonstrated for the first time in the avian retina and pineal organ. These findings underline the structural and functional similarities between the retina and pineal organ and provide additional support for a photoreceptive role of the avian pineal. No specific staining was detected in any other region of the brain in the Japanese quail; the hypothalamic photoreceptors of birds remain unidentified. 相似文献
5.
Paul G. Layer Regina Alber Patrick Mansky Günter Vollmer Elmar Willbold 《Cell and tissue research》1990,259(2):187-198
Summary We report here that similar to E6-chicken retinal cells, dissociated cells from 5.5-day-old (E5.5) quail retinae reaggregate in rotary culture, multiply about tenfold and reestablish histotypical areas. These cellular aggregates include all nuclear layers either with inversed or correct laminar polarity, depending on the local origin of the cells (called rosetted and laminar in-vitro-retinae (IVR), respectively; Layer and Willbold 1989). In combined cultures, chick and quail cells are evenly mixed only during the first two days of culture. Along with the assembly of single cells into rosettes and then into discrete laminae, sectors of chick and quail cells begin to segregate. They are delineated by borders running radially through all three nuclear layers. Thus, interspecies migration of cells at this advanced stage of differentiation is strongly inhibited. Concomitant with this segregation, coherent radial columns spanning all three layers but containing cells from either species only, can be traced histologically. We conclude that a weak segregation of chick and quail retinal cells takes place already at the single cell level, but that the permanent segregation of entire tissue parts must be due to clonal cellular proliferation within the IVR in conjunction with some developmental-structural mechanism retaining clonal progenies within a columnar order.Abbreviations
ECM
extracellular matrix
-
E5.5
days of embryonic age
-
GCL
ganglion cell layer
-
GC's
ganglion cells
-
i.c.
in culture
-
INL
inner nuclear layer
- rosetted in-vitro-retina
retinal cell organoid aggregated from single cells of the central retina
-
IPL
inner plexiform layer
-
MRE
marginal retinal epithelium
-
ONL
outer nuclear layer
-
OPL
outer plexiform layer
-
OS
ora serrate
-
PR
photoreceptor cell
- laminated in-vitro-retina
fully laminated retinal cellorganoid resembling an E15-retina aggregated from cells of the eye periphery including RPE
-
RPE
retinal pigment epithelium 相似文献
6.
Dr. R. G. Foster G. C. Panzica D. M. Parry C. Viglietti-Panzica 《Cell and tissue research》1988,253(2):327-335
Summary Immunocytochemistry was used to determine if photoperiod and/or sex have any effect on the pattern of the luteinizing hormone-releasing hormone (LHRH) system in the brain of the Japanese quail. Immunopositive perikarya were found within three major areas of the brain: the rostral paraolfactory lobe, the preoptic, and the septal region. A quantitative analysis of LHRH cell numbers was performed on male and female quail after two photoperiodic treatments: sexually mature birds exposed to 24 weeks of 20 h light: 4 h darkness (20L4D), and birds with a regressed reproductive system (induced by transfer from a photoregime of 20L4D to 25 short days of 8L16D). Two-way analysis of variance showed that short-day males display significantly (p < 0.05) more immunopositive perikarya (607 + 134) than long-day males (291 + 114), short-day females (293 + 103) or long-day females (330 + 92). The density of LHRH-immunoreactive nerve fibres and the intensity of the immunostaining in the median eminence were always greater in long-day sexually mature quail (male and female) than in animals exposed to 25 days of 8L16D. These results demonstrate that the LHRH system of the quail is influenced by photoperiod and mirrors sexual differentiation. 相似文献
7.
Y Murayama T Ishida M Minezawa A Noguchi O Takenaka 《Journal of medical primatology》1988,17(1):31-40
A cell line (JAMH17+) resistant to 8-azaguanine was established from a human T-cell leukemia virus type 1 related virus (simian T-cell leukemia virus-1) positive Japanese macaque cell line. Lymphoblastic cell lines were established from the peripheral blood mononuclear cells of humans, hominoids, and several species of macaques by coculture with JAMH17+ in hypoxanthine-aminopterin-thymidine medium. HTLV-1 specific antigen was detected in some of the established cell lines. Phenotypic analysis showed that several cell lines of crab-eating macaques expressed Leu11a antigen, which is a marker of human natural killer cells. 相似文献
8.
9.
In an 18 year old Japanese larch stand, leaf characteristics such as area, weight, gross photosynthetic rate and respiration
rate were studied in order to obtain basic information on estimating canopy photosynthesis and respiration. The leaf growth
courses in area and weight from bud opening were approximated by simple logistic curves. The growth coefficient for the area
growth curve was 0.155–0.175 day−1, while that for the weight growth was 0.112–0.117 day−1. The larger growth coefficient in area growth caused the seasonal change in specific leaf area (SLA) that increased after bud opening to its peak early in May at almost 300 cm2 g−1 and then decreased until it leveled off at about 140 cm2g−1. The change inSLA indicates the possibility that leaf area growth precedes leaf thickness growth. The relationship between the coefficientsa andb of the gross photosynthetic rate (p)-light flux density (1) curve (p=bI/(1+aI)) and the mean relative light flux density (I′/I
0) at each canopy height were approximated by hyperbolic formulae:a=A/(I′/I
0)+B andb=C/(I′/I
0)+D. Leaf respiration rate was also increased with increasingI′/I
0. Seasonal change of gross photosynthetic rate and leaf respiration rate were related to mean air temperature through linear
regression on semilogarithmic co-ordinates. 相似文献
10.
N. Aste C. Viglietti-Panzica A. Fasolo C. Andreone H. Vaudry G. Pelletier G. C. Panzica 《Cell and tissue research》1991,265(2):219-230
Summary In the present study, we have demonstrated, by means of the biotin-avidin method, the widespread distribution of neuropeptide Y (NPY)-immunoreactive structures throughout the whole brain of the Japanese quail (Coturnix coturnix japonica). The prosencephalic region contained the highest concentration of both NPY-containing fibres and perikarya. Immunoreactive fibres were observed throughout, particularly within the paraolfactory lobe, the lateral septum, the nucleus taeniae, the preoptic area, the periventricular hypothalamic regions, the tuberal complex, and the ventrolateral thalamus. NPY-immunoreactive cells were represented by: a) small scattered perikarya in the telencephalic portion (i.e. archistriatal, neostriatal and hyperstriatal regions, hippocampus, piriform cortex); b) medium-sized cell bodies located around the nucleus rotundus, ventrolateral, and lateral anterior thalamic nuclei; c) small clustered cells within the periventricular and medial preoptic nuclei. The brainstem showed a less diffuse innervation, although a dense network of immunopositive fibres was observed within the optic tectum, the periaqueductal region, and the Edinger-Westphal, linearis caudalis and raphes nuclei. Two populations of large NPY-containing perikarya were detected: one located in the isthmic region, the other at the boundaries of the pons with the medulla. The wide distribution of NPY-immunoreactive structures within regions that have been demonstrated to play a role in the control of vegetative, endocrine and sensory activities suggests that, in birds, this neuropeptide is involved in the regulation of several aspects of cerebral functions.Abbreviations
AA
archistriatum anterius
-
AC
nucleus accumbens
-
AM
nucleus anterior medialis
-
APP
avian pancreatic polypeptide
-
CNS
centrai nervous system
-
CO
chiasma opticum
-
CP
commissura posterior
-
CPi
cortex piriformis
-
DIC
differential interferential contrast
-
DLAl
nucleus dorsolateralis anterior thalami, pars lateralis
-
DLAm
nucleus dorsolateralis anterior thalami, pars medialis
-
E
ectostriatum
-
EW
nucleus of Edinger-Westphal
-
FLM
fasciculus longitudinalis medialis
-
GCt
substantia grisea centralis
-
GLv
nucleus geniculatus lateralis, pars ventralis
-
HA
hyperstriatum accessorium
-
Hp
hippocampus
-
HPLC
high performance liquid chromatography
-
HV
hyperstriatum ventrale
-
IF
nucleus infundibularis
-
IO
nucleus isthmo-opticus
-
IP
nucleus interpeduncularis
-
IR
immunoreactive
-
LA
nucleus lateralis anterior thalami
-
LC
nucleus linearis caudalis
-
LFS
lamina frontalis superior
-
LH
lamina hyperstriatica
-
LHRH
luteinizing hormone-releasing hormone
-
LoC
locus coeruleus
-
LPO
lobus paraolfactorius
-
ME
eminentia mediana
-
N
neostriatum
-
NC
neostriatum caudale
-
NPY
neuropeptide Y
-
NIII
nervus oculomotorius
-
NV
nervus trigeminus
-
NVI
nervus facialis
-
NVIIIc
nervus octavus, pars cochlearis
-
nIV
nucleus nervi oculomotorii
-
nIX
nucleus nervi glossopharyngei
-
nBOR
nucleus opticus basalis (ectomamilaris)
-
nCPa
nucleus commissurae pallii
-
nST
nucleus striae terminalis
-
OM
tractus occipitomesencephalicus
-
OS
nucleus olivaris superior
-
PA
palaeostriatum augmentatum
-
PBS
phosphate-buffered saline
-
POA
nucleus praeopticus anterior
-
POM
nucleus praeopticus medialis
-
POP
nucleus praeopticus periventricularis
-
PP
pancreatic polypeptide
-
PYY
polypeptide YY
-
PVN
nucleus paraventricularis magnocellularis
-
PVO
organum paraventriculare
-
R
nucleus raphes
-
ROT
nucleus rotundus
-
RP
nucleus reticularis pontis caudalis
-
Rpc
nucleus reticularis parvocellularis
-
RPgc
nucleus reticularis pontis caudalis, pars gigantocellularis
-
RPO
nucleus reticularis pontis oralis
-
SCd
nucleus subcoeruleus dorsalis
-
SCv
nucleus subcoeruleus ventralis
-
SCNm
nucleus suprachiasmaticus, pars medialis
-
SCNl
nucleus suprachiasmaticus, pars lateralis
-
SL
nucleus septalis lateralis
-
SM
nucleus septalis medialis
-
Ta
nucleus tangentialis
-
TeO
tectum opticum
-
Tn
nucleus taeniae
-
TPc
nucleus tegmenti pedunculo-pontinus, pars compacta
-
TSM
tractus septo-mesencephalicus
-
TV
nueleus tegmenti ventralis
-
VeL
nucleus vestibularis lateralis
-
VLT
nucleus ventrolateralis thalami
-
VMN
nucleus ventromedialis hypothalami
A preliminary report of this study was presented at the 15th Conference of European Comparative Endocrinologists, Leuven, Belgium, September 1990 相似文献