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41.
Methods for estimating numbers of motor units in biceps-brachialis muscles and losses of motor units with aging 总被引:4,自引:0,他引:4
This paper presents a new method, here applied to the biceps-brachialis muscles, for estimating motor unit numbers in healthy subjects. This method combines isometric contraction, intramuscular needle electrode recordings, and spike-triggered averaging techniques to measure the sizes of motor unit potentials as recorded in the innervation zone with surface electrodes. The number of motor units is then estimated by division of the maximum biceps-brachialis "M" potential recorded with the same surface electrodes and evoked by supramaximal stimulation of the musculocutaneous nerve, by the mean of at least 10 surface-recorded motor unit potentials. The requisite intramuscular recordings provide additional information as to innervation density, incidence of linked potentials, and impulse blocking, phenomena that are particularly common in neurogenic and myogenic disorders. There was clear evidence of losses of motor units in older subjects: subjects over 60 years of age having approximately half the numbers of motor units of subjects under 60 years of age. 相似文献
42.
Targeted gene disruption of murine CD7 总被引:2,自引:0,他引:2
CD7 is a 40 kDa type I transmembrane glycoprotein member of the Ig
superfamily. CD7 is a marker of mature human T cells and NK cells, and is
expressed early in their development. Cross-linking CD7 positively
modulates T cell and NK cell activity as measured by calcium fluxes,
expression of adhesion molecules, cytokine secretion and proliferation. CD7
associates directly with phosphoinositol 3'-kinase, and CD7 ligation
induces production of D-3 phosphoinositides and tyrosine phosphorylation.
Severe combined immunodeficiency has been associated with a lack of
lymphocyte surface CD7. The CD7 ligand is unknown. The murine CD7 homolog
is encoded by a single gene on chromosome 11. In order to characterize the
role of CD7 in lymphocyte development and function we have eliminated the
CD7 gene by targeted disruption. CD7- deficient mice display normal
histology of thymus and spleen, normal lymphocyte populations in primary
and secondary lymphoid tissues, and normal serum Ig levels. Specific
antibody responses after immunization with T-dependent and T-independent
antigens are equivalent in wild-type and CD7 knockout mice. CD7-deficient
lymphocytes respond normally to T cell mitogenic and allogeneic stimuli,
and display normal NK cell cytotoxicity.
相似文献
43.
44.
Douglas M. Strong John R. Ortaldo Franco Pandolfi Annette Maluish Ronald B. Herberman 《Journal of clinical immunology》1982,2(3):214-221
Cryopreserved human peripheral blood mononuclear cells (PBMC) were tested for natural killer (NK) and antibody-dependent cellular cytotoxicity (ADCC) and for high-affinity (29°C) and total (4°C) rosette formation with sheep erythrocytes. PBMC produced variable NK activity following freezing and thawing, but consistently reacted well in ADCC. A significant correlation was found between low NK activity and a decreased percentage of low-affinity rosette-forming cells. On the contrary, the number of large granular lymphocytes (LGL), among which NK cells are restricted, and the reactivity with the monoclonal antibody OKT10, which recognizes the majority of LGL in the peripheral blood, were not significantly altered by cryopreservation. Cryopreserved cells proved to be excellent controls for determining the day-to-day variability of the NK assay and for selecting optimum conditions for this test in the clinical immunology laboratory. 相似文献
45.
The effects of antioxidant supplementation during Percoll preparation on human sperm DNA integrity 总被引:20,自引:6,他引:20
Hughes CM; Lewis SE; McKelvey-Martin VJ; Thompson W 《Human reproduction (Oxford, England)》1998,13(5):1240-1247
The integrity of sperm DNA is crucial for the maintenance of genetic
health. A major source of damage is reactive oxygen species (ROS)
generation; therefore, antioxidants may afford protection to sperm DNA. The
objectives of the study were, first, to measure the effects of antioxidant
supplementation in vitro on endogenous DNA damage in spermatozoa using the
single cell gel electrophoresis (comet) assay and, second, to assess the
effect of antioxidant supplementation given prior to X-ray irradiation on
induced DNA damage. Spermatozoa from 150 patients were prepared by Percoll
centrifugation in the presence of ascorbic acid (300, 600 microM), alpha
tocopherol (30, 60 microM), urate (200, 400 microM), or acetyl cysteine (5,
10 microM). DNA damage was induced by 30 Gy X-irradiation. DNA strand
breakage was measured using the comet assay. Sperm DNA was protected from
DNA damage by ascorbic acid (600 microM), alpha tocopherol (30 and 60
microM) and urate (400 microM). These antioxidants provided protection from
subsequent DNA damage by X-ray irradiation. In contrast, acetyl cysteine or
ascorbate and alpha tocopherol together induced further DNA damage.
Supplementation in vitro with the antioxidants ascorbate, urate and alpha
tocopherol separately has beneficial effects for sperm DNA integrity.
相似文献
46.
Permanent impairment of embryo development by hydrosalpinges 总被引:6,自引:9,他引:6
Recent reports suggest a deleterious effect of hydrosalpinges on pregnancy
outcome for in-vitro fertilization (IVF) and improvement following surgical
treatment. We compared the effect of hydrosalpinx on pregnancy outcome in
286 patients having 348 IVF cycles and followed the development of
untransferred embryos for 7 days to determine if hydrosalpinges affect
oocyte quality or embryo development. The delivery rate per retrieval was
significantly lower for patients with hydrosalpinx, but was restored by
surgical treatment to that of patients without hydrosalpinx. However, the
implantation rate per embryo transferred and normal blastulation of
untransferred embryos, which were significantly decreased in patients with
hydrosalpinx, and growth arrest and degeneration of untransferred embryos,
which were significantly increased compared to patients without
hydrosalpinx, were not restored by surgical treatment of hydrosalpinges. We
conclude that surgical treatment of hydrosalpinges decreases early
pregnancy loss and improves pregnancy outcome, possibly by diminishing
reversible deleterious effects exerted on the endometrium. As we have seen
in our laboratory, hydrosalpinges may have a permanent negative influence
on ovarian function, follicular development and oocyte quality since
implantation of transferred embryos and normal blastulation of
untransferred embryos remain low, and in-vitro growth arrest and
degeneration remain high despite surgical treatment of hydrosalpinges.
相似文献
47.
Astrid LA. Kuijpers Rolph Pfundt Patrick LJM Zeeuwen Henri OF. Molhuizen Edwin CM. Mariman Peter CM. van de Kerkhof Joost Schalkwijk 《Clinical genetics》1998,54(1):96-101
Psoriasis is a multifactorial skin disease characterised by epidermal abnormalities and infiltration by lymphocytes and polymorphonuclear leukocytes (PMN). Skin-derived antileukoproteinase (SKALP), also known as elafin, is a potent inhibitor of human leukocyte elastase and proteinase 3, two PMN-derived proteinases implicated in tissue destruction and leukocyte migration. We have shown that, at least at the protein level, SKALP is significantly decreased in lesional skin of patients with pustular psoriasis compared with plaque-type psoriasis. This finding raised the possibility that SKALP could be one of the candidate genes for pustular forms of psoriasis. We therefore performed single strand conformation polymorphism (SSCP) analysis on the SKALP gene to screen for mutations/polymorphisms in the exons of 30 patients with plaque-type psoriasis, 15 patients with pustular psoriasis and 48 healthy controls. In exon 1 a polymorphism was detected at position + 43 relative to the translation start site, resulting in a substitution of threonine for alanine in the signal peptide. In the promoter region a dinucleotide repeat polymorphism was identified. Both polymorphisms were not associated with pustular psoriasis, or psoriasis in general. Our data indicate that the decrease in SKALP activity in pustular psoriasis is not caused by mutations in the coding region of the gene, and that there is no allelic association between pustular psoriasis and SKALP gene polymorphisms. 相似文献
48.
Treiber FA Turner JR Davis H Strong WB 《International journal of behavioral medicine》1997,4(4):278-291
Two hundred forty-six children (96 Whites, of whom 51 were mates; 150 African- Americans, of whom 69 were males) with a familial
history of essential hypertension (EH) were re-evaluated 5 years after an initial evaluation. During the initial visit, anthropometric,
demographic, and resting cardiovascular (CV) parameters (designated initial baseline levels) were assessed. These CV parameters
(systolic and diastolic blood pressure [BP], heart rate, cardiac output index [CI], and total peripheral resistance index
[TPRI]) were also measured during postural challenge, a video game challenge, and a cold pressor task. At follow-up, resting
CV parameters were again evaluated, and designated as follow-up resting levels. Moderate temporal stability (r range = .43-.56) was observed for all resting CV parameters. Mean stress responses for each CV parameter for all 3 stressors
during the initial visit were positively related to the respective CV follow-up resting level. BP stress responses to postural
change and video game challenge were found to be significant independent predictors of future resting BP after controlling
for standard EH risk factors. Follow-up resting CI was not predicted by any stress responses, whereas follow-up resting TPRI
was predicted by TPRI responses to the video game after controlling for standard EH risk Factors. These results contrast with
those from an earlier 1-year follow-up. where stress responses for neither CI nor TPRI predicted follow-up resting levels.
It appears that, as children get older. TPRI stress responses play a stronger role in vasoconstrictive function.
This research was supported by National Institutes of Health Grant HL41781. 相似文献
49.
50.
Dal Zotto L; Quaderi NA; Elliott R; Lingerfelter PA; Carrel L; Valsecchi V; Montini E; Yen CH; Chapman V; Kalcheva I; Arrigo G; Zuffardi O; Thomas S; Willard HF; Ballabio A; Disteche CM; Rugarli EI 《Human molecular genetics》1998,7(3):489-499
We have recently reported isolation of the gene responsible for X- linked
Opitz G/BBB syndrome, a defect of midline development. MID1 is located on
the distal short arm of the human X chromosome (Xp22. 3) and encodes a
novel member of the B box family of zinc finger proteins. We have now
cloned the murine homolog of MID1 and performed preliminary expression
studies during development. Mid1 expression in undifferentiated cells in
the central nervous, gastrointestinal and urogenital systems suggests that
abnormal cell proliferation may underlie the defect in midline development
characteristic of Opitz syndrome. We have also found that Mid1 is located
within the mouse pseudoautosomal region (PAR) in Mus musculus , while it
seems to be X- specific in Mus spretus. Therefore, Mid1 is likely to be a
recent acquisition of the M. musculus PAR. Genetic and FISH analyses also
demonstrated a high frequency of unequal crossovers in the murine PAR,
creating spontaneous deletion/duplication events involving Mid1. These data
provide evidence for the first time that genetic instability of the PAR may
affect functionally important genes. In addition, we show that MID1 is the
first example of a gene subject to X-inactivation in man while escaping it
in mouse. These data contribute to a better understanding of the molecular
content and evolution of the rodent PAR.
相似文献