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排序方式: 共有3095条查询结果,搜索用时 15 毫秒
21.
Grossman M Koenig P DeVita C Glosser G Moore P Gee J Detre J Alsop D 《Neuropsychology》2003,17(4):658-674
Patients with probable Alzheimer's disease (AD) have difficulty understanding verbs. To investigate the neural basis for this deficit, the authors used functional magnetic resonance imaging to examine patterns of neural activation during verb processing in 11 AD patients compared with 16 healthy seniors. Subjects judged the pleasantness of verbs, including MOTION verbs and COGNITION verbs. Healthy seniors and AD patients both activated posterolateral temporal and inferior frontal regions during judgments of verbs. These activations were relatively reduced and somewhat changed in their anatomic distribution in AD patients compared with healthy seniors, particularly for the subcategory of MOTION verbs, but AD patients showed minimal activation in association with COGNITION verbs. These findings imply that poor performance with verbs in AD is due in part to altered activation of the large-scale neural network that supports verb processing. 相似文献
22.
In recent years, fluorescence microscopy based on two-photon excitation has become a popular tool for biological and biomedical imaging. Among its advantages is the enhanced depth penetration permitted by fluorescence excitation with the near-infrared photons, which is particularly attractive for deep-tissue imaging. To fully utilize two-photon fluorescence microscopy as a three-dimensional research technique in biology and medicine, it is important to characterize the two-photon imaging parameters in a turbid medium. We investigated the two-photon point spread functions (PSFs) in a number of scattering samples. Gel samples containing 0.1-microm fluorescent microspheres and Liposyn III were used as phantoms mimicking the turbid environment often found in tissue. A full characterization of the two-photon PSFs of a water and oil immersion objective was completed in samples composed of 0, 0.25, 0.5, 1, and 2% Liposyn III. Our results show that up to depths of about 100 (oil) and 200 microm (water), the presence of scatterers (up to 2% Liposyn III) does not appreciably degrade the PSF widths of the objectives. 相似文献
23.
Mr S. B. Bidiwala M. S. Mansour C. K. Stengel S. A. Klein S. M. Carroll S. C. Koenig A. H. Desoky G. R. Tobin C. Maldonado J. H. Barker 《Medical & biological engineering & computing》1998,36(5):621-626
Investigations into the changes that occur in microvasculature following the surgical procedure called delay have brought
about the need for a computer system capable of quantifying the morphological features of a full microvascular network in
terms of average vessel length, diameter, and tortuosity. Both the formulaic conventions that have been developed to measure
these quantities as well as their implementation in the form of a HP-9000/UNIX based computer software system that we developed
specifically for this purpose are discussed. Reliability studies performed using the final system to measure the microcirculatory
network of a mouse latissmus dorsi muscle (LDM) showed 95% confidence intervals within 5% of means and coefficients of variability
within 7% of means for all quantities measured in large (150–300 μm), medium (50–150 μm), and small (<50 μm) diameter vessels.
These variations were significantly smaller than the changes that were observed in a preliminary study comparing these microvascular
network parameters before and after delay in the hairless mouse LDM, showing the proposed quantification methods to be well
suited to the study of the microvascular changes following delay. It is hoped that the formulaic conventions, implementation
process and reliability data will provide a useful comparison for other researchers interested in measuring similar features
of microcirculatory networks. 相似文献
24.
Frataxin is reduced in Friedreich ataxia patients and is associated with mitochondrial membranes 总被引:17,自引:8,他引:17
Campuzano V; Montermini L; Lutz Y; Cova L; Hindelang C; Jiralerspong S; Trottier Y; Kish SJ; Faucheux B; Trouillas P; Authier FJ; Durr A; Mandel JL; Vescovi A; Pandolfo M; Koenig M 《Human molecular genetics》1997,6(11):1771-1780
Friedreich ataxia is a progressive neurodegenerative disorder caused by
loss of function mutations in the frataxin gene. In order to unravel
frataxin function we developed monoclonal antibodies raised against
different regions of the protein. These antibodies detect a processed 18
kDa protein in various human and mouse tissues and cell lines that is
severely reduced in Friedreich ataxia patients. By immunocytofluorescence
and immunocytoelectron microscopy we show that frataxin is located in
mitochondria, associated with the mitochondrial membranes and crests.
Analysis of cellular localization of various truncated forms of frataxin
expressed in cultured cells and evidence of removal of an N-terminal
epitope during protein maturation demonstrated that the mitochondrial
targetting sequence is encoded by the first 20 amino acids. Given the
shared clinical features between Friedreich ataxia, vitamin E deficiency
and some mitochondriopathies, our data suggest that a reduction in frataxin
results in oxidative damage.
相似文献
25.
J I Koenig 《Toxicologic pathology》1989,17(2):256-265
The hypothalamus receives neuronal afferents from numerous sources including inputs from limbic structures, such as the amygdala and hippocampus, and from brainstem regions involved in the regulation of the cardiovascular system and other autonomic functions. These afferents using a vast array of neurotransmitters and neuropeptides influence the activity of the hypothalamic neurons which synthesize and secrete the hypothalamic releasing and release-inhibiting factors into the hypophyseal portal circulatory system. The afferents can modulate the activity of the hypothalamic neurons by forming synapses on the neuronal cell body, on the nerve terminals in the median eminence or both. The chemicals most frequently used as neurotransmitters are the biogenic amines, including the catecholamines (norepinephrine, dopamine and epinephrine), serotonin, acetylcholine and gamma-aminobutyric acid (GABA). The stimulatory influence of norepinephrine, serotonin, and acetylcholine on the secretion of corticotropin (ACTH) in rodents and man will be discussed, whereas GABA exerts an inhibitory effect on the secretion of ACTH in both man and rodents. These effects appear to be mediated by changes in the secretion of the corticotropin-releasing hormone (CRH) and vasopressin into the hypophyseal portal circulation. Numerous neuropeptides appear to alter the secretion of ACTH in the rat. We will discuss the stimulatory actions of neuropeptide Y (NPY), angiotensin II, and peptides of immune cell origin on the secretion of ACTH and CRH. The opioid peptides inhibit the secretion of CRH into the portal blood, however, they exert a potent stimulatory effect on prolactin secretion in the rat and man.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
26.
A new method to assess attachment representations in children by applying a story completion procedure in doll play (SCPDP) is presented. Transmission and continuity of attachment were tested in 28 German families by using the Strange Situation procedure (SS) with the mother and her infant, the Adult Attachment Interview (AAI) with the mother when the child is 5 years old, and the attachment representations (SCPDP) of the 6-year-olds. Relying on the twofold distinction (secure/insecure), results revealed a significant continuity of attachment from 1 to 6 years of age, and a correspondence between maternal AAI and child's attachment quality in SS, as well as a correspondence between maternal AAI and the 6-year-olds' attachment representations. Using configural frequency analysis, we found continuity in patterns of security and insecurity when looking across the measures of infant and pre-school attachment and maternal adult attachment. Processes underlying the high match of mothers' and children's attachment representations are discussed. 相似文献
27.
Yang GC; Croaker D; Zhang AL; Manglick P; Cartmill T; Cass D 《Human molecular genetics》1998,7(6):1047-1052
Lethal white foal syndrome (LWFS) is a congenital anomaly of horses
characterized by a white coat colour and aganglionosis of the bowel, which
is similar to Hirschsprung disease (HSCR). We decided to investigate
possible mutations of the endothelin-B receptor gene ( EDNRB ) in LWFS as
recent studies in mutant rodents and some patients have demonstrated EDNRB
defects. First, we identified a full-length cDNA for horse EDNRB . This
cDNA fragment contained a 1329 bp open reading frame which encoded 443
amino acid residues. The predicted amino acid sequence was 89, 91 and 85%
identical to human, bovine and mouse as well as rat EDNRB respectively, but
only 55% identical to the human, bovine and rat endothelin A receptor
(EDNRA). Secondly, sequence analysis, together with allele-specific PCR and
the amplification- created restriction site (ACRS) technique, revealed a
dinucleotide TC-- >AG mutation, which changed isoleucine to lysine in
the predicted first transmembrane domain of the EDNRB protein. This was
associated with LWFS when homozygous and with the overo phenotype when
heterozygous.
相似文献
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30.
J J Trout H Koenig A D Goldstone C Y Lu 《Laboratory investigation; a journal of technical methods and pathology》1986,55(6):622-631
Polyamines have been previously implicated in the mediation of blood-brain barrier breakdown induced by cryogenic injury (H Koenig, AD Goldstone, CY Lu, Biochem Biophys Res Commun 116:1039, 1983). We studied acute (less than 5 minute) changes in capillary ultrastructure, microvascular permeability, and the levels of polyamines and their rate regulating synthetic enzyme ornithine decarboxylase (ODC) in rat cerebral cortex after focal cold injury. Microvascular permeability was measured by relative transport of intravenously administered fluorescein. Capillary ultrastructure was studied by quantitative stereology and morphometry after intravenous administration of horseradish peroxidase. Focal cold injury induced a 2.5-, 3.8-, 1.7-, and 1.4-fold increase in the levels of ODC, putrescine, spermidine and spermine, and a 46-fold increase in fluorescein uptake in perilesional cortex. Few capillaries in control cortex contained endocytic pits or horseradish peroxidase-positive vesicles, whereas most capillaries near lesions showed these structures. Cryoinjury induced a 5-fold increase in the relative volume of microvilli and horseradish peroxidase vesicles, a 2.3-fold increase in area of luminal endocytic pits, and a 6.3-fold increase in area of abluminal exocytic pits. The ODC inhibitor alpha-difluoromethylornithine blocked the cryoinjury-induced changes in ODC, polyamines, fluorescein uptake, and capillary ultrastructure. Putrescine negated the effect of alpha-difluoromethylornithine or capillary ultrastructure, and was previously shown to nullify the alpha-difluoromethylornithine effects on polyamines and fluorescein permeability (cited above). These data link rapid changes in ODC and polyamines to blood-brain barrier breakdown, and suggest that the abnormal permeability is associated with an acute, polyamine-mediated stimulation of microvillus formation, endocytosis, and vesicular transport in capillary endothelium. 相似文献