全文获取类型
收费全文 | 11860篇 |
免费 | 813篇 |
国内免费 | 183篇 |
专业分类
耳鼻咽喉 | 115篇 |
儿科学 | 259篇 |
妇产科学 | 426篇 |
基础医学 | 1554篇 |
口腔科学 | 401篇 |
临床医学 | 1132篇 |
内科学 | 2624篇 |
皮肤病学 | 211篇 |
神经病学 | 935篇 |
特种医学 | 427篇 |
外国民族医学 | 3篇 |
外科学 | 1900篇 |
综合类 | 260篇 |
一般理论 | 4篇 |
预防医学 | 615篇 |
眼科学 | 117篇 |
药学 | 668篇 |
1篇 | |
中国医学 | 47篇 |
肿瘤学 | 1157篇 |
出版年
2023年 | 73篇 |
2022年 | 124篇 |
2021年 | 346篇 |
2020年 | 187篇 |
2019年 | 257篇 |
2018年 | 319篇 |
2017年 | 221篇 |
2016年 | 267篇 |
2015年 | 304篇 |
2014年 | 390篇 |
2013年 | 497篇 |
2012年 | 818篇 |
2011年 | 801篇 |
2010年 | 453篇 |
2009年 | 390篇 |
2008年 | 657篇 |
2007年 | 774篇 |
2006年 | 609篇 |
2005年 | 628篇 |
2004年 | 597篇 |
2003年 | 513篇 |
2002年 | 513篇 |
2001年 | 349篇 |
2000年 | 349篇 |
1999年 | 345篇 |
1998年 | 132篇 |
1997年 | 123篇 |
1996年 | 91篇 |
1995年 | 84篇 |
1994年 | 99篇 |
1993年 | 73篇 |
1992年 | 173篇 |
1991年 | 161篇 |
1990年 | 132篇 |
1989年 | 151篇 |
1988年 | 84篇 |
1987年 | 121篇 |
1986年 | 84篇 |
1985年 | 56篇 |
1984年 | 67篇 |
1983年 | 43篇 |
1982年 | 26篇 |
1981年 | 30篇 |
1980年 | 27篇 |
1979年 | 46篇 |
1978年 | 23篇 |
1976年 | 32篇 |
1975年 | 22篇 |
1974年 | 29篇 |
1972年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Michele D. Mignogna Stefano Fedele Lucio Lo Russo Lorenzo Lo Muzio 《Journal of oral pathology & medicine》2003,32(4):200-205
BACKGROUND: The recurrent chronic orofacial swelling caused by orofacial granulomatosis (OFG) can cause significant cosmetic and functional problems but can be prevented if the disease is diagnosed early and promptly treated. Although the enlargement of the lips is described to be the most common presenting complaint, the clinical onset of OFG may be characterized by minor associated mucosal and neurological manifestations, making early diagnosis very difficult or, sometimes, merely presumable. PATIENTS AND METHODS: We retrospectively analyzed the clinical manifestations of 19 patients with OFG, who were examined at our institution between 1998 and 2002, in order to determine their initial manifestations and presenting symptoms. RESULTS: A total of 10 patients showed classical recurrent enlargement of the lips (six lower; four upper) as presenting symptom. In the other nine patients, OFG onset was characterized by transient unilateral facial nerve palsy (two cases), intraoral manifestations (two cases), recurrent swelling of the periorbital area (two cases), of the chin (one case), of the zygomatic area (one case), and of the cheeks (one case). CONCLUSION: Our data underlined that OFG onset could be frequently characterized by widely variable, multiform, and temporary clinical findings. Involvement of atypical sites of the orofacial region and presence of single minor manifestations may occur as presenting symptoms, often preceding the development of traditional clinical findings. 相似文献
2.
C W Scott D P Blowers P T Barth M M Lo A I Salama C B Caputo 《Journal of neuroscience research》1991,30(1):154-162
Three isoforms of human tau protein were compared for their abilities to induce microtubule assembly. The three isoforms, tau 3 (tau containing three microtubule-binding domains), tau 4 (tau containing four microtubule-binding domains) and tau 4L (tau containing four microtubule binding domains plus a 58-amino-acid insert near the N-terminus) were expressed in E. coli and purified using ammonium sulfate precipitation, ion exchange, and size exclusion chromatography. All three isoforms induced microtubule assembly at micromolar concentrations and showed similar critical concentrations for assembly of 0.4-0.45 microM. However, tau 4 induced microtubule formation at a rate five- to tenfold faster than either tau 3 or tau 4L. The rate of microtubule elongation seen with tau 4 was twofold greater than with tau 3 or tau 4L, suggesting that the faster rate of microtubule assembly seen with tau 4 was due, at least in part, to faster elongation. Tau 4 induced a greater number of microtubules to form at steady state than did tau 3 or tau 4L. The microtubules generated with each tau isoform had similar steady-state length distributions and were equally susceptible to cold-induced disassembly. These results indicate that the additional microtubule-binding domain in tau 4 enhances microtubule assembly, while the 58-amino-acid insert negates the stimulatory effect of the fourth microtubule-binding domain. 相似文献
3.
Cerebrovascular and metabolic perturbations in delayed heavy charged particle radiation injury 总被引:5,自引:0,他引:5
E H Lo K A Frankel R L Delapaz A Poljak K H Woodruff K M Brennan M H Phillips P E Valk G K Steinberg J I Fabrikant 《Brain research》1989,504(1):168-172
Focal heavy charged particle irradiation of the rabbit brain created defined lesions which were observable by nuclear magnetic resonance (NMR) and positron emission tomography (PET) imaging techniques. The lesions appeared approximately 9-11 months after left partial hemibrain irradiation with 30 Gy (230 MeV/u helium ions), and were restricted to the white matter tracts and deep perithalamic and thalamic regions. 82Rubidium PET and Gadolinium DTPA enhanced NMR imaging were used to detect blood-brain barrier perturbations. 18Fluordeoxyglucose PET studies demonstrated widespread decreases in cerebral glucose uptake in the cortex and thalamus of the irradiated hemisphere. NMR and PET imaging results correlated well with histological findings. Rabbits irradiated with 15 Gy did not demonstrate any abnormalities in the brain with sequential NMR scans through 14 months post-irradiation. 相似文献
4.
Expression of tau protein in non-neuronal cells can result in a redistribution of the microtubule cytoskeleton into thick bundles of tau-containing microtubules (Lewis et al.: Nature 342:498-505, 1989; Kanai et al.: J Cell Biol 109:1173-1184, 1989). We reconstituted microtubule bundles using purified tubulin and tau in order to study the assembly of these structures. Taxol-stabilized tubulin polymers were incubated with various concentrations of recombinant human tau and examined by electron microscopy. With increasing concentrations of tau 3 (tau isoform containing three microtubule binding domains) or tau 4 (isoform containing four microtubule binding domains) the microtubules changed orientation from a random distribution to loosely and tightly packed parallel arrays and then to thick cables. In contrast, tau 4L, the tau isoform containing four microtubule binding domains plus a 58-amino acid insert near the N-terminus, showed minimal bundling activity. tau 4-induced bundling could be inhibited by the addition of 0.5 M NaCl or 0.4 mM estramustine phosphate, conditions which are known to inhibit tau binding to microtubules. A tau construct that contained only the microtubule binding domains plus 19 amino acids to the C-terminus was fully capable of bundling microtubules. Phosphorylation of tau 3 with cAMP-dependent protein kinase had no effect on its ability to induce microtubule bundling. These results indicate that tau protein is directly capable of bundling microtubules in vitro, and suggests that different tau isoforms differ in their ability to bundle microtubule filaments. 相似文献
5.
Amy C Y Lo Alvin K H Cheung Victor K L Hung Chung-Man Yeung Qing-Yu He Jen-Fu Chiu Stephen S M Chung Sookja K Chung 《Journal of cerebral blood flow and metabolism》2007,27(8):1496-1509
Previously, we reported that transgenic mice overexpressing endothelin-1 in astrocytes showed more severe neurological deficits and increased infarct after transient focal ischemia. In those studies, we also observed increased level of aldose reductase (AR), the first and rate-limiting enzyme of the polyol pathway, which has been implicated in osmotic and oxidative stress. To further understand the involvement of the polyol pathway, the mice with deletion of enzymes in the polyol pathway, AR, and sorbitol dehydrogenase (SD), which is the second enzyme in this pathway, were challenged with similar cerebral ischemic injury. Deletion of AR-protected animals from severe neurological deficits and large infarct, whereas similar protection was not observed in mice with SD deficiency. Most interestingly, AR(-/-) brains showed lowered expression of transferrin and transferrin receptor with less iron deposition and nitrotyrosine accumulation. The protection against oxidative stress in AR(-/-) brain was also associated with less poly(adenosine diphosphate-ribose) polymerase (PARP) and caspase-3 activation. Pharmacological inhibition of AR by Fidarestat also protected animals against cerebral ischemic injury. These findings are the first to show that AR contributes to iron- and transferrin-related oxidative stress associated with cerebral ischemic injury, suggesting that inhibition of AR but not SD may have therapeutic potential against cerebral ischemic injury. 相似文献
6.
Geste antagonistes, or sensory tricks, are well described in focal dystonia affecting the neck, hand, and face. Improvement in dystonic movements is typically maintained while the trick is performed, but disappears when the geste ends. We investigated the phenomenological features of geste antagoniste maneuvers in 19 patients with idiopathic lower cranial dystonia who were prospectively evaluated over a period of 6 years. Of the 19, 10 were men, mean age of onset was 49.8 years, and the most commonly involved lower cranial area was the jaw (10 patients). In most patients, dystonia was task-specific. Taking advantage of the improvement with a sensory geste, we manufactured oral appliances that mimicked the geste in 8 patients, and 3 continue to use it. 相似文献
7.
Treatment of Paget's disease of bone with intravenous 4-amino-1-hydroxybutylidene-1,1-bisphosphonate
S. Adami G. Salvagno G. Guarrera F. Montesanti S. Garavelli S. Rosini V. Lo Cascio 《Calcified tissue international》1986,39(4):226-229
Summary 4-amino-1-hydroxybutylidene-1,1-bis-phosphonate (AHButBP) was given intravenously (2.5–25 mg/day for 4 days) to 14 patients
with Paget's disease of bone, five of whom had been treated with dichloromethylidene bisphosphonate (Cl2MBP) 32 months earlier. In the nine patients who had not been treated previously with bisphosphonates, the short course of
AHButBP induced a suppression of serum alkaline phosphatase and urinary hydroxyproline values down to 30% of initial values.
The biochemical suppression of the disease was sustained for 2–18 months and the time to relapse did correlate to the logarithm
of the dose (P<0.001). In the five patients previously treated for Paget's disease, an apparent resistence to treatment with AHButBP was
observed. However, in these patients both serum alkaline phosphatase and urinary hydroxyproline fell to or even below the
nadir values which had previously been achieved with Cl2MBP, irrespective of the degree of relapse. Thus the degree of suppression of Paget's disease of bone, achievable after treatment
with bisphosphonates, seems to be constant for each patient, such that normal levels of serum alkaline phosphatase and urinary
hydroxyproline cannot usually be attained in patients with extremely active disease. 相似文献
8.
9.
G M Simpson K G Yadalam D F Levinson M J Stephanos E S Lo T B Cooper 《Journal of clinical psychopharmacology》1990,10(6):417-421
Fluphenazine decanoate is commonly used as part of maintenance treatment of schizophrenia, but its pharmacokinetics are poorly understood. We administered a single intramuscular dose of fluphenazine decanoate to nine patients and found that plasma fluphenazine level did not decline to 50% of the peak level by day 26 in any of the patients. This means that it has a long half-life measurable in months rather than weeks. 相似文献
10.
TNF alpha and Fas mediate tissue damage and functional outcome after traumatic brain injury in mice.
Daniela Bermpohl Zerong You Eng H Lo Hyung-Hwan Kim Michael J Whalen 《Journal of cerebral blood flow and metabolism》2007,27(11):1806-1818
Tumor necrosis factor-alpha (TNFalpha) and Fas are induced after traumatic brain injury (TBI); however, their functional roles are incompletely understood. Using controlled cortical impact (CCI) and mice deficient in TNFalpha, Fas, or both (TNFalpha/Fas-/-), we hypothesized that TNFalpha and Fas receptor mediate secondary TBI in a redundant manner. Compared with wild type (WT), TNFalpha/Fas-/- mice had improved motor performance from 1 to 4 days (P<0.05), improved spatial memory acquisition at 8 to 14 days (P<0.05), and decreased brain lesion size at 2 and 6 weeks after CCI (P<0.05). Protection in TNFalpha/Fas-/- mice from histopathological and motor deficits was reversed by reconstitution with recombinant TNFalpha before CCI, and TNFalpha-/- mice administered anti-Fas ligand antibodies had improved spatial memory acquisition versus similarly treated WT mice (P<0.05). Tumor necrosis factor-alpha/Fas-/- mice had decreased the numbers of cortical cells with plasmalemma damage at 6 h (P<0.05 versus WT), and reduced matrix metalloproteinase-9 activity in injured brain at 48 and 72 h after CCI. In immature mice subjected to CCI, genetic inhibition of TNFalpha and Fas conferred beneficial effects on histopathology and spatial memory acquisition in adulthood (both P<0.05 versus WT), suggesting that the beneficial effects of TNFalpha/Fas inhibition may be permanent. The data suggest that redundant signaling pathways initiated by TNFalpha and Fas play pivotal roles in the pathogenesis of TBI, and that biochemical mechanisms downstream of TNFalpha/Fas may be novel therapeutic targets to limit neurological sequelae in children and adults with severe TBI. 相似文献