全文获取类型
收费全文 | 45598篇 |
免费 | 3706篇 |
国内免费 | 1384篇 |
专业分类
耳鼻咽喉 | 217篇 |
儿科学 | 1027篇 |
妇产科学 | 543篇 |
基础医学 | 7429篇 |
口腔科学 | 1085篇 |
临床医学 | 3222篇 |
内科学 | 7433篇 |
皮肤病学 | 940篇 |
神经病学 | 3708篇 |
特种医学 | 679篇 |
外国民族医学 | 5篇 |
外科学 | 3467篇 |
综合类 | 6167篇 |
现状与发展 | 4篇 |
预防医学 | 2048篇 |
眼科学 | 544篇 |
药学 | 6749篇 |
4篇 | |
中国医学 | 2159篇 |
肿瘤学 | 3258篇 |
出版年
2024年 | 76篇 |
2023年 | 755篇 |
2022年 | 1703篇 |
2021年 | 1957篇 |
2020年 | 1497篇 |
2019年 | 1741篇 |
2018年 | 1713篇 |
2017年 | 1606篇 |
2016年 | 1439篇 |
2015年 | 1514篇 |
2014年 | 2531篇 |
2013年 | 2733篇 |
2012年 | 2303篇 |
2011年 | 2766篇 |
2010年 | 2188篇 |
2009年 | 2183篇 |
2008年 | 2203篇 |
2007年 | 1970篇 |
2006年 | 1817篇 |
2005年 | 1722篇 |
2004年 | 1621篇 |
2003年 | 1496篇 |
2002年 | 1315篇 |
2001年 | 988篇 |
2000年 | 940篇 |
1999年 | 864篇 |
1998年 | 702篇 |
1997年 | 680篇 |
1996年 | 573篇 |
1995年 | 511篇 |
1994年 | 449篇 |
1993年 | 333篇 |
1992年 | 269篇 |
1991年 | 276篇 |
1990年 | 210篇 |
1989年 | 182篇 |
1988年 | 185篇 |
1987年 | 142篇 |
1986年 | 154篇 |
1985年 | 329篇 |
1984年 | 312篇 |
1983年 | 242篇 |
1982年 | 273篇 |
1981年 | 214篇 |
1980年 | 199篇 |
1979年 | 181篇 |
1978年 | 135篇 |
1977年 | 94篇 |
1976年 | 103篇 |
1975年 | 91篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
The present study examined the influences of dopamine (DA) receptor stimulation on enkephalin (Met5-enkephalin; ME) and tachykinin (substance P; SP) systems of basal ganglia of Sprague-Dawley rats, lesioned as neonates with 6-hydroxydopamine (6-OHDA). It has been proposed that the neonatal 6-OHDA-lesioned rat could serve as a model for the DA deficiency and self-injurious behavior (SIB) observed in the childhood neurological disorder. Lesch-Nyhan syndrome. In agreement with earlier work, the present study found that the neonatal 6-OHDA treatment at 3 days of age, reduced DA and caused an increase in ME and a decrease in SP content in the striatum and substantia nigra, when tested as adults. Administration of the DA precursor, L-dihydroxyphenylalanine (L-DOPA), to lesioned animals, induced SIB; increased DA and DOPAC levels; produced a greater decrease (-64%) in SP levels in the striatum and substantia nigra than was observed with lesion alone (-28%). The L-DOPA-induced decrease in SP levels and the SIB observed in the lesioned animals were blocked by pretreatment with the D1 receptor antagonist, SCH-23390. Moreover, administration of the D1 receptor agonist, SKF-38393, but not the D2 agonist, LY-171555, to lesioned animals mimicked the L-DOPA responses in all respects, except that the agonists did not alter DA or DOPAC levels. None of the DA agonists or antagonists treatments affected lesion-induced increase in ME levels in the striatum. These results indicate for the first time, that SIB precipitated by DA agonists in neonatal dopaminergic denervated animals, is associated with a marked and selective decrease in SP in the striatonigral SP neurons. This process has two components: (a) a retarded development of the SP system due to neonatal dopaminergic denervation: and (b) a depletion of the remaining SP, presumably by enhanced release due to D1 DA receptor-mediated activation of striatonigral SP neurons. 相似文献
52.
目的 :探讨血清可溶性白细胞介素 2受体 (sIL 2R)在慢性乙型病毒性肝炎 (慢乙肝 )中的发病机制及sIL 2R与肝纤维化指标、肝功能的相关关系。方法 :对 312例肝活检病人按组织病理学炎症和纤维化程度进行分级分期 ,同时检测了病人血清sIL 2R、肝功能及肝纤维化相关指标。结果 :血清sIL 2R均值较对照组明显增高 (P <0 .0 1) ,增幅随着肝脏病理炎症和纤维化程度的加重而逐渐加大 ,各组间比较差异有显著性 (P <0 .0 5或P <0 .0 1)。sIL 2R与血清白蛋白 (A)呈显著负相关 ,与血清脯氨酸肽酶 (PLD)、Ⅳ型胶原 (CⅣ )、层粘连蛋白 (LN)、透明质酸 (HA)、Ⅲ型前胶原氨基端肽 (PⅢNP)、肝功指标中的TB、DB、G、ALT、AST、AKP、γ GT呈显著正相关 (P <0 .0 5或P <0 .0 1)。结论 :慢乙肝病人血清sIL 2R水平与A呈显著负相关 ,与PLD、CⅣ、LN、HA、PⅢNP呈显著正相关 ;sIL 2R的血清水平能反映肝脏组织学病变的程度 ,可作为判断肝组织炎症和纤维化程度的参考指标。 相似文献
53.
54.
KENICHI TATSUMI TSUNEATSU MORI ETSUKO MORI HIDEHARU KANZAKI TAKAHIDE MORI 《American journal of reproductive immunology (New York, N.Y. : 1989)》1987,13(3):87-92
ABSTRACT: The culture supernatant of the TTK-1 cell line, established from human decidual tissue, was found to contain a factor that strongly suppressed the mixed lymphocyte reaction (MLR). The mechanism of the MLR-suppressive activity as well as the biochemical characterization of this factor was analyzed. The TTK-1 supernatant suppressed the MLR much more strongly than the culture supernatants of the three other malignant cell lines examined. The molecular weight of this factor was estimated to be between 43 kilodaltons (kd) and 67 kd by gel filtration chromatography. The TTK-1 supernatant also suppressed the proliferation of the interleukin 2 (IL-2)-dependent T cell lines, but did not suppress that of the IL-2-independent T cell lines, suggesting that the TTK-1 supernatant inhibited the action of IL-2 and subsequently suppressed the MLR. The fact that the TTK-1 cell line originated from human decidual tissue might imply the important role of this factor in immunological fetomaternal balance. 相似文献
55.
目的 :探讨“云克”(99Tc MDP)治疗类风湿性关节炎 (RA)的免疫机制。方法 :采用ELISA双抗体夹心法 ,观察“云克”体外对RA患者外周血单核细胞 (PBMC)产生白介素 1(IL 1)和可溶性白介素 2受体 (sIL 2R)的影响。结果 :“云克”有抑制RA患者IL 1的分泌及细菌脂多糖 (LPS)的促分泌作用 ,并对可溶性白介素 2受体的自发分泌及植物血素 (PHA)诱导分泌均有抑制作用。结论 :“云克”对RA的治疗机制可能与其降低IL 1和sIL 2R的作用有关 相似文献
56.
Effects of antimicrobial agents on spontaneous and endotoxin-induced cytokine release of human peripheral blood mononuclear cells 总被引:2,自引:0,他引:2
U. Krehmeier M. Bardenheuer G. Voggenreiter U. Obertacke F. U. Schade M. Majetschak 《Journal of infection and chemotherapy》2002,8(2):194-197
Because the immunomodulatory effects of antibiotics could possibly influence the degree of the systemic and local response
to infection, knowledge of their intrinsic influence on the host's inflammatory response appears to be essential. Therefore,
this study investigated the effects of frequently used antimicrobial agents (β-lactams, quinolones gentamicin, vancomycin
and metronidazole) on the in-vitro tumor necrosis factor (TNF)-α and interleukin (IL)-6 production of isolated human peripheral
blood mononuclear cells (PBMNC), cultured with or without endotoxin, in comparison with those effects obtained in a whole-blood
assay system. In the presence of ciprofloxacin, ofloxacin, gentamicin, vancomycin, and metronidazole, a significant inhibition
of the endotoxin-stimulated TNF-α production of human peripheral blood mononuclear cells (PBMNC) was found at therapeutic
levels. Only ofloxacin showed a significant inhibitory influence on the endotoxin-induced IL-6 production of PBMNC. In the
whole-blood assay, significant effects were not detectable. None of the antibiotics showed cytotoxicity. It is concluded that,
at present, the direct immunological effects of antibiotics should be interpreted carefully with regard to the experimental
conditions, and regardless of the therapeutic implications. To assess the potential direct immunomodulatory effect of antimicrobial
agents, different cell culture procedures should be used.
Received: October 19, 2001 / Accepted: February 15, 2002 相似文献
57.
Transplantation of microencapsulated bovine chromaffin cells reduces lesion-induced rotational asymmetry in rats 总被引:7,自引:0,他引:7
Surrounding bovine chromaffin cells by a semipermeable membrane may protect the transplanted cells from a host immune response and shield them from the inflammatory process resulting from the surgical trauma. Encapsulation of the chromaffin cells was achieved by inter-facial adsorption of a polycation on a polyanionic colloid matrix in which the chromaffin cells were entrapped. Basal and potassium-evoked release of catecholamines from encapsulated bovine chromaffin cells was analyzed over a 4-week period in vitro. Norepinephrine and dopamine release remained constant over time whereas epinephrine release significantly decreased. The chromaffin cells also retained the capacity for depolarization-elicited catecholamine release 4 weeks following the encapsulation procedure. Morphological analysis revealed the presence of intact chromaffin cells with well-preserved secretory granules. Striatial implantation of chromaffin cell-loaded capsules significantly reduced apomorphine-induced rotation compared to empty polymer capsules in animals lesioned with 6-hydroxydopamne frr at least 4 weeks. Intact chromaffin cells expressing tyrosine hydroxylase and dopamine-β-hydroxylase were observed in all capsules implanted in the striatum for 4 weeks. The assessment of the clinical potential of transplanting encapsulated adrenal chromaffin cells of either allo- or xenogeneic origin for Parkinson's disease will require long-term behavioral studies. The present study suggests, however, that the polymer encapsulation procedure may offer an alternative to adrenal autografts as a source of dopaminergic tissue. 相似文献
58.
We performed an open, double-blind, and long-term study of vigabatrin (gamma-vinyl-GABA, GVG) in patients with treatment-resistant epilepsy who were receiving only one or at most two standard antiepileptic drugs (AEDs). The novel design included a parallel, double-blind, placebo-controlled phase that minimized the number of patients receiving placebo and allowed determination of the optimum dose of GVG for each patient before initiation of the double-blind phase. The study was divided into four phases. The first phase was a 6-week period of baseline observation. In the second phase, GVG was added openly to previous AEDs for 8 weeks. During the first 2 weeks of this phase, the dose of GVG was increased weekly and then, in the absence of adverse effects, was held constant for the next 6 weeks. At the end of this open phase, seizure frequency during the 6 weeks of constant treatment was compared with the baseline seizure frequency for each patient. Patients who experienced reduction greater than 50% in the frequency of any seizure type during the open phase were defined as responders. These responders were then entered into the third and double-blind phase, in which they were randomly allocated wither to continue active GVG treatment or placebo for 8 weeks. Thirty-three patients entered the study; 31 of 33 patients completed the initial open phase. Twenty patients achieved a reduction greater than or equal to 50% in the frequency of one or more seizure types and were eligible for the double-blind phase; 10 were randomized to continue GVG and 10 were randomized to placebo.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
59.
益肾调督针法对实验大鼠脑梗死恢复期TNF-α、IL-6和IL-8的影响 总被引:4,自引:0,他引:4
目的 观察益肾调督针法对脑梗死恢复期治疗及预防再梗的作用机制。方法 将实验大鼠随机分为对照组、模型组、益肾调督针法组、常规针法组和非穴针刺组各10例,用血栓栓塞法制备局灶性脑梗死模型,观察治疗前后大鼠神经功能改变,应用双抗体夹心ELISA法分别测定各组大鼠血清中TNF-α、IL-6和IL-8的含量。结果 治疗前后大鼠神经功能评分以益。肾调督针法组及常规针法组有效,差异具有显著性(P〈0.01);模型组大鼠血清中TNF.仅、IL-6和IL.8含量较对照组明显升高(P〈0.01),施予针刺治疗后各针法组含量均有不同程度的下降。结论 益肾调督针法可以有效地抑制TNF-α、IL-6和IL-8的表达.从而在脑梗死恢复期治疗及预防再梗方面发挥作用。 相似文献
60.
目的观察卡维地洛对不稳定型心绞痛(UAP)患者高敏C反应蛋白(hs-CRP)、白介素-6(IL-6)及细胞间可溶性黏附分子1(sICAM-1)水平的影响。方法UAP患者62例采用完全随机化方法分成对照组(n=30)和治疗组(n=32),在常规抗血小板、扩血管治疗基础上,对照组予美托洛尔(12.5mg,2次/d×3d)口服,治疗组服卡维地洛(6.25mg,2次/d×3d),在治疗前后分别测定hs-CRP、IL-6、sICAM-1值。结果对照组和治疗组在治疗前hs-CRP、IL-6、sICAM-1均无显著性差异;用药后两组3指标均较用药前显著降低(P<0.05);治疗组在用药后IL-6、sI-CAM-1显著低于对照组(P<0.05)。同时,用药后两组患者的心率、血压、心肌耗氧量均较用药前显著降低(P<0.05),治疗组的心肌耗氧量显著低于对照组(P<0.05)。结论卡维地洛可显著降低UAP患者的炎症因子IL-6、sICMA-1水平。 相似文献