全文获取类型
收费全文 | 11669篇 |
免费 | 1054篇 |
国内免费 | 453篇 |
专业分类
耳鼻咽喉 | 67篇 |
儿科学 | 159篇 |
妇产科学 | 248篇 |
基础医学 | 1925篇 |
口腔科学 | 226篇 |
临床医学 | 873篇 |
内科学 | 1990篇 |
皮肤病学 | 437篇 |
神经病学 | 417篇 |
特种医学 | 185篇 |
外国民族医学 | 2篇 |
外科学 | 684篇 |
综合类 | 1340篇 |
现状与发展 | 4篇 |
一般理论 | 1篇 |
预防医学 | 1191篇 |
眼科学 | 147篇 |
药学 | 1826篇 |
8篇 | |
中国医学 | 927篇 |
肿瘤学 | 519篇 |
出版年
2024年 | 32篇 |
2023年 | 209篇 |
2022年 | 233篇 |
2021年 | 622篇 |
2020年 | 441篇 |
2019年 | 420篇 |
2018年 | 435篇 |
2017年 | 462篇 |
2016年 | 442篇 |
2015年 | 486篇 |
2014年 | 693篇 |
2013年 | 941篇 |
2012年 | 675篇 |
2011年 | 725篇 |
2010年 | 631篇 |
2009年 | 588篇 |
2008年 | 561篇 |
2007年 | 510篇 |
2006年 | 416篇 |
2005年 | 396篇 |
2004年 | 357篇 |
2003年 | 307篇 |
2002年 | 273篇 |
2001年 | 250篇 |
2000年 | 201篇 |
1999年 | 199篇 |
1998年 | 186篇 |
1997年 | 137篇 |
1996年 | 148篇 |
1995年 | 132篇 |
1994年 | 148篇 |
1993年 | 97篇 |
1992年 | 90篇 |
1991年 | 98篇 |
1990年 | 81篇 |
1989年 | 84篇 |
1988年 | 52篇 |
1987年 | 56篇 |
1986年 | 49篇 |
1985年 | 87篇 |
1984年 | 55篇 |
1983年 | 42篇 |
1982年 | 37篇 |
1981年 | 29篇 |
1980年 | 21篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1976年 | 6篇 |
1972年 | 6篇 |
1970年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
The age-dependence of the incidence of magnocellular neurosecretory neurons containing abnormal accumulations of peptide in the rough endoplasmic reticulum was examined in homozygous Brattleboro rats and in their wild-type Long Evans counterparts. Neurons in which the immunophenotype of the peptide aggregates indicate that somatic cross-over mutations involving the 5' end of the vasopressin gene and the 3' end of the oxytocin gene have occurred, increased with age in homozygous Brattleboro rats, reaching a maximum of 24 cells per hypothalamus (approximately 0.6% of the vasopressin neurons). The increase occurred in both male and female animals but was significantly greater in females. The average incidence of such cells was 6 times greater in the supraoptic than in the paraventricular nucleus. No such cells could be detected in either nucleus of Long Evans rats despite the evidence for hybrid mRNA in these animals. Moreover, no accumulation of peptide translated from the hybrid mRNAs derived from the 5' end of the oxytocin gene and the 3' end of the vasopressin gene could be detected in either Brattleboro or Long Evans animals. These results strongly suggest that the accumulation of peptide in the rough endoplasmic reticulum of vasopressin neurons in homozygous Brattleboro rats is due to an abnormality other than the somatic crossing-over mutation. A second type of abnormal magnocellular neuron with accumulations of peptide in the rough endoplasmic reticulum, in which the immunophenotype of the peptide reveals products derived only from the oxytocin precursor, was present in both Long Evans and Brattleboro rats, but did not increase with age in Brattleboro rats. The incidence of these cells was similar in the supraoptic and paraventricular nuclei. 相似文献
62.
目的 探讨高级糖化终产物与糖尿病并发症的关系。方法 采用本实验室自行研制的竞争性酶联免疫吸附分析方法,测定了糖尿病有并发症组病人血浆95例,糖尿病无并发症组人血浆65例,正常对照65例。结果:在糖尿病有并发症组中,高级糖化终产物(AGEs)浓度[(6.625(1.691)U/mL,n=95]明显高于糖尿病无并发症组[(5.904(2.071)U/mL,n=65,P=0.017],也明显高于正常人组[(5.337(1.138,n=65,p〈0.005]。以有无并发症为应变量进行多元logistic回归分析显示,血浆AGEs浓度〉6.085U/ml者,糖尿病并发症发生的危险性增加(OR值为2.989,95%可信限为1.407—6.350)。多元逐步线性回归显示:糖尿病病程、冠心病史与血浆AGEs浓度之间有线性关系。结论血浆AGEs浓度是糖尿病发生并发症的独立危险因素。 相似文献
63.
Carla Testorell Carlo Pruneri Luigi Ferini-Strambi Marco Zamperetti Carlo A. Altamura Salvatore Smirne Silvio R. Bareggi 《Human psychopharmacology》1993,8(6):423-428
Serum immunoglobulins and the activity of natural killer (NK) cells of 50 epileptic patients (eight with idiopathic generalized epilepsy and 42 with cryptogenic partial epilepsy) and 28 controls have been studied. The values of IgA, IgG and IgM were the same-in patients and controls. The NK activity in controls was linearly related to the effector-to-target ratio, but this linear relationship was not observed in epileptic patients. The cytotoxic activity of NK cells at the lowest effector-to-target ratio was significantly greater in patients than in controls. This increase was observed in each therapy group. Our results seem to confirm a disturbance of the immune system in epileptic patients and suggest that this modification of cellular immunity is not a drug effect but is related to the illness itself. 相似文献
64.
It is controversial whether gastrooesophageal reflux disease represents a spectrum disease from a nonerosive to a complicated one, or whether it is a categorial disease, i.e. it can be divided into three categories, such as nonerosive gastrooesophageal reflux disease, erosive gastrooesophageal reflux disease and Barrett's esophagus (BE) with little or no transition from one category to the other. This controversy might be of general interest, because it has some implications in the management of the patient. However, literature data concerning the natural history of gastrooesophageal reflux disease are very limited, and in particular very few papers have dealt with the issue of describing the natural history of patients with nonerosive gastrooesophageal reflux disease. Aim of the present review is to reassess these scanty data, and to try to demonstrate that progression from milder to more severe forms of gastrooesophageal reflux disease is possible and documented. 相似文献
65.
目的:研究不同孕期阶段(早、中、晚)孕妇凝血四项、血浆纤维蛋白(原)降解产物[plasma fibrin/fibrinogen degradation products, FDP]、D-二聚体的变化及临床意义,为临床诊疗提供理论支持。方法:回顾性分析2021年1月至2021年12月200例孕妇就诊资料中的凝血四项,纤维蛋白原(fibrinogen, FIB)、凝血酶原时间(prothrombin time, PT)、凝血酶时间(thrombin time, TT)、活化部分凝血活酶时间(activated partial thromboplastin time, APTT)。并对FDP与D-二聚体的检测结果进行统计分析,比较孕早期、中期、晚期三个阶段凝血四项、FDP和D-二聚体水平的变化。结果:孕早期、孕中期与孕晚期PT水平比较,差异有统计学意义(P<0.05);孕早期、孕中期与孕晚期三个阶段的TT相比,差异无统计学意义(P>0.05);孕早期的APTT明显长于中期、晚期孕妇,差异有统计学意义(P<0.05);孕早期、中期、晚期孕妇,随着孕周的增加,FIB水平逐渐升高... 相似文献
66.
67.
Natural killer/T-cell lymphoma (NKTL) and peripheral T-cell lymphomas (PTCL) are prevalent in the Asian population and exhibit a high association with the Epstein-Barr virus (EBV). Moreover, differentiation of these two groups is often difficult and problematic. We investigated 35 cases of NKTL (22 nasal cases and 13 extranasal cases) and 30 cases of PTCL in terms of their clinical features, immunohistology, EBV positivity, EBV strain-type polymorphism and latent membrane protein 1 (LMP1) deletion variant distribution. Eighteen cases (82%) of nasal NKTL and seven (54%) of extranasal NKTL showed EBV positivity by EBV in situ hybridization. Fifteen cases (50%) of PTCL revealed EBV positivity. EBV strain type A was predominant in NKTL (18:5), and EBV strain types A and B were distributed evenly in PTCL (6:6). EBV-positive patients had significantly shorter survival than EBV-negative patients (P < 0.05), and EBV positivity correlated with advanced clinical stage (P < 0.05). Patients harboring type A EBV showed slightly poorer prognoses than those having type B, though it was not obviously statistically different (P = 0.07). The LMP1 deletion variant was prevalent in both NKTL (three wild-type LMP1, 15 deletion variants) and PTCL (three wild-type LMP1, eight deletion variants, two coexistent forms) patients, but did not have prognostic impact. Our results indicate that EBV acts as a negative prognostic factor in NKTL and PTCL, and that the intrinsic properties of a specific viral strain might influence the clinical behavior of these diseases. 相似文献
68.
Changes in activity of some mechanisms of specific and nonspecific immunity in vitamin B1 deficiency
A. D. Pletsityi 《Bulletin of experimental biology and medicine》1979,88(1):741-743
The effect of thiamine deficiency on the immune response and activity of certain mechanisms of natural immunity was studied in adult rats. Thiamine deficiency was simulated experimentally by a single injection of hydroxythiamine, a vitamin B1 antagonist. Administration of hydroxythiamine caused a marked decrease in complement activity, phagocytic activity of the peripheral blood leukocytes, bactericidal activity of the serum, and antibody production in response to immunization with sheep's red blood cells. Conversely, lysozyme activity increased. In vitamin B1 deficiency the intensity of incorporation of [14C]leucine into liver protein synthesis was reduced.Department of Pathological Physiology, N. I. Sechenov First Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR G. V. Vygodchikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 7, pp. 60–62, July, 1979. 相似文献
69.
目的:研究自然杀伤(NK)细胞在异基因骨髓移植中对移植物抗宿主病(GVHD)、移植排斥、骨髓植入及造血重建的影响。方法:以近交系小鼠C57/6j(H-2b)为供鼠、BALB/c(H-2d)为受鼠,在移植物中增加供者的外周T细胞和/或NK细胞进行异基因骨髓移植,用流式细胞仪检测受鼠的CD34+细胞计数和H-2Kb+细胞表达水平,血细胞自动分析仪检测外周血白细胞计数,并结合临床表现和病理检查,比较不同移植组的存活率、GVHD、植入水平及造血重建等。结果:增加NK细胞组的小鼠存活率显著大于不增加NK细胞组,小鼠出现GVHD的数量少、程度轻,外周血白细胞及骨髓CD34+细胞恢复快、H-2Kb+细胞表达水平高。结论:NK细胞抑制小鼠异基因骨髓移植中的GVHD和移植排斥,促进骨髓植入及造血重建。 相似文献
70.
Nagata H Numata T Konno A Mikata I Kurasawa K Hara S Nishimura M Yamamoto K Shimizu N 《Pathology international》2001,51(10):778-785
Chronic active Epstein-Barr virus infection (CAEBV) is a syndrome that takes diverse clinical courses and is often associated with lymphoproliferative disorders of T/natural killer (NK)-cell lineage. We describe a patient with CAEBV associated with persistent pharyngeal ulcer, and with subsequent nasal T/NK-cell lymphoma in her neck lymph nodes and nasopharynx. Immunophenotyping of lymphoid cells showed that the lineage of Epstein-Barr virus (EBV)-positive cells in the patient was of NK-cell origin. By means of high-dose recombinant interleukin-2, we established an EBV-positive cell line of NK-cell lineage from her peripheral blood. Southern blot analysis for the number of terminal repeat sequences of EBV detected three NK-cell clones in the patient's lymph node. One of these clones was identical to the established cell line but was not observed in the pharyngeal ulcer, while the other two clones were present in the pharyngeal ulcer. These results suggest that the patient had expansion of the three NK-cell clones, one of which had proliferative capacity in vitro and was involved in the formation of the lymphoma. Moreover, the results suggest that the proliferative capacity of EBV-positive cells can be variable even in a single patient, and this variability may explain the clinical diversity in CAEBV. 相似文献