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991.
Tomohiko Ai M. Horie Kazuhiko Obayashi Shigetake Sasayama 《Pflügers Archiv : European journal of physiology》1998,436(2):168-174
To examine mechanism(s) underlying the accentuated antagonism by angiotensin II (A-II) on twitch tension, we recorded L-type
Ca2+ currents (I
Ca,L) using conventional patch-clamp techniques in single, guinea-pig, ventricular myocytes. I
Ca,L was recorded by a step-pulse protocol after eliminating K+ conductances (internal Cs+ plus tetraethylammonium chloride and K+-free extracellular solution). A-II (100 nM) did not affect basal I
Ca,L, but inhibited I
Ca,L that had been enhanced (approximately 200% of control) by (ISO, isoproterenol 100 nM). The inhibitory action of A-II was
concentration dependent (concentration eliciting 50% inhibition 88±9 pM, n=41) and the ISO-enhanced component of I
Ca,L was completely blocked by A-II at concentrations above 10 nM. CV-11974 (500 nM), an A-II type-1 receptor (AT1) antagonist, prevented the inhibitory action of A-II. Pre-incubation with pertussis toxin (PTX) abolished the inhibitory
effect of A-II. A-II also inhibited the I
Ca,L enhanced by histamine (500 nM) and forskolin (1 μM), but failed to affect I
Ca,L enhanced by intracellular cyclic adenosine monophosphate (1 mM). The inhibitory action of A-II may therefore involve AT1 receptors/PTX-sensitive, guanine nucleotide-binding (G) proteins (Gi)/adenylate cyclase and partially explains the A-II-dependent
accentuated antagonism of inotropy. 相似文献
992.
采集450例战士血清标本,分别用国家代表株甲3/济防/15/90(H3N2)和甲3/北京/32/92(H3N2)作血清血凝抑制抗体测定,青年对甲3型抗体阳性率为60%~67%,其GMT为34~45。1994~1995年两年中在军营人群中分离到3株H3N2毒株流行株,分别应用国际、国家和地方代表株作抗原性分析,证明流行株与它们之间抗原性有明显差异。本文分离到的3株流行株均上送国家流感中心鉴定,证实为H3N2亚型毒株。 相似文献
993.
994.
对28例Graves病的可溶性白介素2受体(sIL2R)和各种甲状腺激素以及甲状腺自身抗体治疗前后比较,并进行逐步回归,结果表明:治疗后Graves病患者除TSH外,各种甲状腺激素及甲状腺自身抗体显著降低(P<001),并对sIL2R的上升与下降呈显著相关。 相似文献
995.
Cytotoxic T lymphocytes (CTL) recognize antigens derived from endogenously expressed proteins presented on the cell surface in the context of major histocompatibility complex (MHC) class I molecules. Because CTL are effective in antiviral and antitumor responses, the delivery of antigens to the class I pathway has been the focus of numerous efforts. Generating CTL by immunization with exogenous proteins is often ineffective because these antigens typically enter the MHC class II pathway. This review focuses on the usefulness of bacterial toxins for delivering antigens to the MHC class I pathway. Several toxins naturally translocate into the cytosol, where they mediate their cytopathic effects, and the mechanisms by which this occurs has been elucidated. Molecular characterization of these toxins identified the functional domains and enabled the generation of modified proteins that were no longer toxic but retained the ability to translocate into the cytosol. Thus, these modified toxins could be examined for their ability to carry peptides or whole proteins into the cytosolic processing pathway. Of the toxins studied—diphtheria, pertussis, Pseudomonas, and anthrax—the anthrax toxin appears the most promising in its ability to deliver large protein antigens and its efficiency of translocation. 相似文献
996.
Desipramine (DMI, 15 mg/kg, s.c.) decreased [3H]CGP-12177-labelled cortical β-adrenoceptor density (Bmax) by 30% upon chronic (14 day) treatment. However, even a single dose (in mg/kg) of DMI (15) or the β-adrenoceptor agonist, clenbuterol (20), induced a rapid (24 hour) and significant reduction of β-adrenoceptor Bmax (−15%; p<0.01). Acute treatment with amitryptiline (10), clorgyline (1), fluoxetine (10), nomifensine (10) or maprotiline (20) had no significant effect on [3H]CGP-12177-labelled β-adrenoceptors, suggesting that rapid down-regulation may not be a general property of antidepressant drugs. None of the antidepressants altered the Bmax of [3H]ketanserin-labelled 5-HT2A receptors on acute treatment. These results show that β-adrenoceptor down-regulation by clenbuterol and DMI is not dependent on chronic treatment and may, therefore, be a poor correlate of the gradual onset of therapeutic efficacy seen clinically with antidepressant drugs. 相似文献
997.
In an attempt to establish an in vitro/in situ correlation of intestinal permeability data, the permeability coefficients (P
app) for a series of model peptides, which were determined using an in situ perfused rat ileum model, were compared to the permeability coefficients (P
mono) determined using an in vitro cell culture model (Caco-2). The model peptides, which were all blocked on the N-terminal (acetyl, Ac) and the C-terminal (amide, NH2) ends, consisted of D-phenylalanine (F) residues (e.g., AcFNH2, AcFFNH2, AcFFFNH2). To alter the degree of hydrogen bonding potential, the nitrogens of the amide bonds were sequentially methylated [e.g., AcFF(Me)FNH2, AcF(Me)F(Me)FNH2, Ac(Me)F(Me)F(Me)FNH2, Ac-(Me)F(Me)F(Me)FNH(Me)]. These peptides were shown not to be metabolized in the in situ perfused rat ileum system. The results of the transport experiments showed that there were poor correlations between the apparent permeability coefficients (P
app) determined in an in situ perfused rat ileum model and the octanol–water partition coefficients (r = 0.60) or the hydrogen bonding numbers (r = 0.63) of these peptides. However, good correlations were observed between the in situ
P
app values for these peptides and their partition coefficients in heptane–ethylene glycol (r = 0.96) and the differences in their partition coefficients between octanol–water and isooctane–water (r = 0.86). These results suggest that lipophilicity may not be the major factor in determining the intestinal permeability of these peptides and that hydrogen bonding potential may be a major contributing factor. A good correlation (r = 0.94) was also observed between the P
app values determined for these peptides in the in situ perfused ileum model and those P
mono values determined in the in vitro cell culture model (Caco-2) (Conradi et al., Pharm. Res. 8:1453–1460, 1991). These results suggest that the permeability values determined in the Caco-2 cell culture model may be a good predictor of the intestinal permeability of peptides. 相似文献
998.
氯菊酯可明显抑制Ca~(2+)—ATP酶活性,其抑制作用是可逆的,底物动力学分析表明为非竞争性抑制,介质的酸度可影响其抑制效应;氯氰菊酯对该酶活性无明显影响.氯菊酯和氯氰菊酯均能可逆性地抑制Ca~(2+),Mg~(2+)—ATP酶活性,但氯菊酯为反竞争性抑制.且有一定的pH依赖性,而氯氰菊酯为非竞争性抑制,其抑制率基本不受pH的影响,表明这两种杀虫剂在Ca~(2+) ,Mg~(2+)—ATP酶上有不同的结合位点. 相似文献
999.
M. M. Moens A. V. Mertens L. S. De Clerck H. P. Van Bever C. H. Bridts W. J. Stevens 《Pediatric allergy and immunology》1993,4(2):89-92
In patients with allergic asthma and rhinitis high numbers of hypodense eosinophils (HE) have been demonstrated. In a previous study we reported that asthmatic and healthy children had more HE than their adult counterparts. We assumed that this might, in part, he due to the presence of immature eosinophils in children. To distinguish between immature and activated eosinophils, determination of eosinophil cationic protein (ECP) might be interesting as it is known that high serum levels of ECP are associated with increased activation of eosinophiis. In this study we determined (he levels of ECP in scrum in asthmatic and healthy children and adults trying to distinguish activated from immature eosinophils. We found that ECP levels were not increased in children (healthy and asthmatic) compared to adults (healthy and asthmatic). This supports the hypothesis that increased numbers of HE in childhood are, at least in part, immature eosinophils. Nevertheless, we could confirm that inflammation was present in children because soluble interleukin-2-receptor (slL-2R), a marker of lymphocyte activation, was higher in asthmatic children as compared to healthy children. IL-6, a marker of macrophage/monocyte activation, was not different in the different patient groups. We conclude that although signs of inflammation are present in childhood asthma, the increased numbers of HE in children are in part due to the presence of immature eosinophils. 相似文献
1000.
J. W. Constantine W. S. Lebel H. A. Woody 《Naunyn-Schmiedeberg's archives of pharmacology》1990,342(6):722-724
Summary Neurokinin A, neurokinin B and substance P caused concentration-related contractions of rabbit isolated aorta with pD2 values of 8.1, 6.9 and 6.0, respectively. [D-Pro2, D-Trp7,9]-substance P, a competitive tachykinin antagonist, had pA2 values of 5.3 against neurokinin A, 5.1 against neurokinin B and 5.2 against substance P indicating that tachykinin receptors
mediated responses to the agonists. [pGIu5,MePhe8,-McGly9]-substance P 5–11 (DiMe-C7), senktide and septide did not contract the aorta. It is concluded that of the known tachykinin
receptors smooth muscle of the rabbit isolated aorta contains only the NK-2 type.
Send offprint requests to J. W. Constantine at the above address 相似文献