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31.
Summary Mutants of Saccharomyces cerevisiae were selected that would interact with ochre (UAA) suppressors so as to allow ochre -suppressor dependant amber (UAG) suppression, but which do not exhibit opal (UGA) suppression. Strains mutant at four distinct loci were isolated, and two of these are recessive mutations while the other two behave as dominants or semidominants. MOS3 has some suppressor activity in the absence of a resident SUP4-o gene and shares other characteristics with previously described omnipotent suppressors. MOS4, mos1 and mos2, on the other hand, exhibit no suppressor activity in the absence of a resident SUP4-o gene but do exhibit suppression of UAG alleles when there is a resident SUP4-o gene. These latter modifier strains do not interact with a SUP4-o gene to suppress UGA alleles. By genetic and physiological criteria the MOS4, mosl, and most mutations appear to be different than previously described allosuppressors or modifiers of suppression. 相似文献
32.
Role of NK cells and gamma interferon in transplacental passage of Toxoplasma gondii in a mouse model of primary infection 总被引:7,自引:0,他引:7
Abou-Bacar A Pfaff AW Georges S Letscher-Bru V Filisetti D Villard O Antoni E Klein JP Candolfi E 《Infection and immunity》2004,72(3):1397-1401
Protective immunity in mice infected with Toxoplasma gondii is mainly mediated by NK cells, CD4 and CD8 T cells, and type 1 cytokines, such as gamma interferon (IFN-gamma). To clarify the roles of NK cells and IFN-gamma in protection against primary congenital toxoplasmosis, we used recombination activating gene 2 knockout (RAG-2(-/-)) mice, which lack T and B lymphocytes, in comparison with the wild-type BALB/c model. RAG-2(-/-) mice had a significantly lower risk of fetal toxoplasmosis than BALB/c mice (25 versus 63.9%; P = 0.003). This protection was associated with an increased number of maternal NK cells, IFN-gamma secretion by spleen cells, and decreased parasitemia. In the RAG-2(-/-) mice, NK cell depletion increased both the rate of fetal infection, to 56.5% (P = 0.02), and the blood parasite burden. Conversely, in the BALB/c mice, this treatment did not modify maternofetal transmission or the blood parasite burden. Neutralization of IFN-gamma in both infected RAG-2(-/-) and BALB/c mice decreased congenital Toxoplasma transmission, contrasting with an exacerbation of maternal infection. These data suggest that a partially protective immunity against congenital toxoplasmosis is achieved due to the increased number of NK cells in RAG-2(-/-) mice. However, it seems that IFN-gamma enhances, directly or indirectly, the transplacental transmission. 相似文献
33.
Mechanisms of peptide YY release induced by an intraduodenal meal in rats: neural regulation by proximal gut 总被引:5,自引:0,他引:5
Fu-Cheng Xiaomei Anini Younes Chariot Jacques Castex Nathalie Galmiche Jean-Paul Rozé C. 《Pflügers Archiv : European journal of physiology》1997,433(5):571-579
Peptide YY (PYY) release in anaesthetized rats was studied during the 2 h following the intraduodenal administration of a
semi-liquid meal of 21 kJ. Surgical and pharmacological manipulations were performed in order to analyse the mechanisms of
PYY release. Postprandial PYY release was suppressed or strongly decreased by caecocolonectomy, truncal vagotomy, tetrodotoxin,
hexamethonium, sensory denervation by perivagal capsaicin, and by the NO-synthase inhibitor L-N-arginine methyl ester, while atropine, adrenergic blockers, antagonists of type-A or type-B cholecystokinin (CCK) receptors
or bombesin receptors had no effect. Comparing the digestive transit of the semi-liquid meal with the amount of PYY contained
in the small bowel wall showed that nutrients had not reached the area rich in cells containing PYY by 30 min, the time at
which there was a large PYY release in plasma. By 120 min, the meal front had travelled 72% of the small intestine length,
just beginning to reach the PYY-rich part of the ileum. We conclude that the main postprandial PYY release studied in this
model comes from ileal and colonic L-cells indirectly stimulated through a neural mechanism originating in the proximal gut
and involving sensory vagal fibres, nicotinic synapses and NO release, while CCK and bombesin do not seem to be physiologically
involved.
Received: 17 July 1996 / Received after revision: 11 October 1996 / Accepted: 18 October 1996 相似文献
34.
Lamellar cells of sensory receptors and perineural cells of nerve endings of pig skin contain cytokeratins 总被引:1,自引:0,他引:1
Jean-Paul Ortonne Patrick Verrando Gérard Pautrat Michel Darmon 《Virchows Archiv : an international journal of pathology》1987,410(6):547-552
Summary The lamellar cells of the sensory corpuscles of the pig dermis must be considered to be epithelial cells as they contain cytokeratins. The cytokeratins detected are similar to those found in simple epithelia. Moreover, lamellar cells are embedded in an extracellular matrix reminiscent of the basement membrane of epithelium since it contains laminin and collagen IV. The perineural cells surrounding the nerves of pig dermis present the same features.These results suggest that lamellar cells and perineural cells have the same origin. The nature of the lamellar and perineural cells of the rabbit or human dermis is not as clear since cytokeratins were not detected in those cells. These results, together with recent observations on Merkel cells, may indicate that epithelio-neuronal junctions are a general feature of cutaneous sensory receptors. 相似文献
35.
Jean-Paul Trilles Michel Bariche 《Acta parasitologica / Witold Stefański Institute of Parasitology, Warszawa, Poland》2006,51(3):223-230
Cymothoa indica, a typical Indo-Pacific genus and species, is reported for the first time in the eastern Mediterranean Sea. Specimens were
found parasitizing mainly barracudas (Sphyraenidae) from Lebanon. Female and male specimens are described on collected materials.
To date, the genus Cymothoa has not been reported in the Mediterranean Sea although it is widely represented in other areas of the world. It is suggested
that C. indica should be added to the list of exotic species introduced from the Red Sea and known as Lessepsian migrants. 相似文献
36.
Summary Three methods for analyzing the spatial organization of visual evoked potentials were compared. Pattern reversal visual evoked potentials were obtained from a single subject under three viewing conditions: stimulation of the left, right, and both visual fields. The scalp distribution of the VEP to 1 deg checks was displayed using three recording and analysis techniques: a conventional horizontal occipital array of electrodes, topographic mapping, and 3-dimensional evoked potentials. All three techniques revealed "paradoxical" lateralization of P100. The relative merits of each technique are discussed.We are grateful to Susan Hoffmann-Nader and Rebecca Clark-Bash for data collection. This research was supported in part by the Brain Research Foundation of the University of Chicago. 相似文献
37.
Alain Verloes Yves Gillerot Jean-Paul Langhendries Jean-Pierre Fryns Lucien Koulischer 《American journal of medical genetics. Part A》1992,43(4):669-677
We report on a case of neonatal hypothalamic hamartoblastoma with holoprosencephaly, Hirschsprung disease, and tetramelic postaxial polydactyly. Twenty-seven previous cases of congenital hypothalamic embryonic tumours with associated congenital defects are reviewed. A classification in isolated, associated, and syndromal forms is proposed. The difficulties encountered in differential diagnosis between the syndromal form (mainly represented by the Pallister-Hall syndrome) and related diseases as Smith-Lemli-Opitz type II, holoprosencephaly-polydactyly, orofaciodigital type VI and hydrolethalus syndromes are outlined. Two pathogenic mechanisms are discussed: a classical pleiotropic model and single sequence model. The latter is sufficient to delineate syndromal hypothalamic hamartoblastoma. With the former, syndromal hypothalamic hamartoblastoma cannot be clearly recognized in the absence of a CNS tumour, a child with syndromal hypothalamic hamartoblastoma cannot be reliably diagnosed as Pallister-Hall rather than another MCA syndrome, and, ultimately, the existence of Pallister-Hall syndrome could be questioned, as it could only be the extreme expression of one or several other syndromes. As this hypothesis cannot be proven or disproven at this point, the authors suggest creating the concept of multiplex phenotype. “Cerebro-Acro-Visceral Early lethality multiplex syndrome” is suggested to encompass all the ambiguous cases. Within this complex, an operative classification key is proposed. © 1992 Wiley-Liss, Inc. 相似文献
38.
Reix P Fortier PH Niyonsenga T Arsenault J Létourneau P Praud JP 《Respiratory physiology & neurobiology》2003,134(3):209-218
Swallowing is a powerful inhibitor of respiratory rhythm in infants. The present study was aimed at investigating the influence of states of alertness on non-nutritive swallowing (NNS) frequency, on NNS and respiration coordination, and on bursts of NNS frequency in newborn lambs. Six full term newborn lambs were instrumented for electroencephalogram, eye movement, diaphragm and thyroarytenoid muscle electromyogram, nasal flow and electrocardiogram. Polysomnographic recordings were performed in non-sedated lambs, using radiotelemetry. NNS frequency was significantly higher during quiet wakefulness (W) and active sleep (AS) than during quiet sleep (QS). NNS mainly interrupted inspiration and the transition phases between expiration and inspiration, especially in W and AS. Bursts of NNS occurred significantly more often during AS. This study highlights the relevance of the ovine model to study ontogeny of NNS during sleep, and documents the influence of sleep on NNS and respiration coordination. 相似文献
39.
Maria-Cristina Cuturi Rgis Josien Diego Cantarovich Laurence Bugeon Ignacio Anegon Sverine Menoret Helga Smit Patrice Douillard Jean-Paul Soulillou 《European journal of immunology》1994,24(7):1627-1631
Permanent tolerance to allografts can be induced in adult rats by donor-specific transfusions (DST) prior to transplantation. We have previously reported, in a model of heart allograft, the presence of a heavy leukocyte infiltrate, in the allograft which displayed a strong allospecific cytotoxicity when tested in vitro against donor cells, and a strong accumulation of mRNA for granzyme A and perforin in vivo. In contrast, there was a major decrease in the accumulation of mRNA for interleukin-2 and interferon-γ. These results suggested that the DST-induced tolerance was associated with a decrease in type-1 T helper (Th1) cell function. The major role of preformed antibodies in xeno and allorejection is clearly established. Nevertheless, the consequences of alloantibody production in acute rejection and tolerance induction remains to be elucidated. We here analyze the alloantibody response in rejecting and DST-treated recipients. We show that, after transplantation, tolerant recipients, in contrast to rejecting ones, mount a low IgM alloresponse that switches to low IgG production. Detailed analysis of IgG alloantibodies in DST-treated recipients revealed that their production decrease was not equally distributed. Whereas rejecting animals mounted a strong anti-class I and II IgG alloantibody response, DST-treated recipients produced anti-class II and low titers of anti-class I IgG alloantibodies. Furthermore, among IgG subclasses, tolerant recipients predominantly produced IgG2a, a profile which, in the rat, is compatible with a Th2-controlled response. Finally, the passive transfer of immune serum from rejecting animals to DST-treated recipients could abrogate the tolerance. We suggest that the absence of anti-class I alloantibodies combined with preserved and/or increased anti-class II production plays a major role in graft tolerance in this model. These results reinforced the role of alloantibodies in rejection and in induction of tolerance. 相似文献
40.