全文获取类型
收费全文 | 1908篇 |
免费 | 183篇 |
国内免费 | 58篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 91篇 |
妇产科学 | 22篇 |
基础医学 | 160篇 |
口腔科学 | 45篇 |
临床医学 | 200篇 |
内科学 | 326篇 |
皮肤病学 | 32篇 |
神经病学 | 29篇 |
特种医学 | 257篇 |
外科学 | 92篇 |
综合类 | 238篇 |
预防医学 | 234篇 |
眼科学 | 35篇 |
药学 | 187篇 |
中国医学 | 127篇 |
肿瘤学 | 61篇 |
出版年
2023年 | 12篇 |
2022年 | 39篇 |
2021年 | 53篇 |
2020年 | 59篇 |
2019年 | 29篇 |
2018年 | 44篇 |
2017年 | 56篇 |
2016年 | 44篇 |
2015年 | 77篇 |
2014年 | 88篇 |
2013年 | 134篇 |
2012年 | 151篇 |
2011年 | 123篇 |
2010年 | 118篇 |
2009年 | 125篇 |
2008年 | 86篇 |
2007年 | 85篇 |
2006年 | 56篇 |
2005年 | 46篇 |
2004年 | 28篇 |
2003年 | 20篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 14篇 |
1999年 | 15篇 |
1998年 | 78篇 |
1997年 | 53篇 |
1996年 | 63篇 |
1995年 | 45篇 |
1994年 | 49篇 |
1993年 | 44篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 11篇 |
1989年 | 39篇 |
1988年 | 27篇 |
1987年 | 25篇 |
1986年 | 19篇 |
1985年 | 12篇 |
1984年 | 16篇 |
1983年 | 15篇 |
1982年 | 14篇 |
1981年 | 20篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 16篇 |
1976年 | 8篇 |
1975年 | 11篇 |
1973年 | 2篇 |
排序方式: 共有2149条查询结果,搜索用时 31 毫秒
21.
Mutations in Emery-Dreifuss muscular dystrophy and their effects on emerin protein expression 总被引:2,自引:1,他引:2
Manilal S; Recan D; Sewry CA; Hoeltzenbein M; Llense S; Leturcq F; Deburgrave N; Barbot J; Man N; Muntoni F; Wehnert M; Kaplan J; Morris GE 《Human molecular genetics》1998,7(5):855-864
Seventeen families with Emery-Dreifuss muscular dystrophy (EDMD) have been
studied both by DNA sequencing and by emerin protein expression. Fourteen
had mutations in the X-linked emerin gene, while three showed evidence of
autosomal inheritance. Twelve of the 14 emerin mutations caused early
termination of translation. An in-frame deletion of six amino acids from
the C-terminal transmembrane helix caused almost complete absence of emerin
from muscle with no localization to the nuclear membrane, although mRNA
levels were normal. This shows that mutant emerin proteins are unstable if
they are unable to integrate into a membrane. A 22 bp deletion in the
promoter region was expected to result in reduced emerin production, but
normal amounts of emerin of normal size were found in leucocytes and
lymphoblastoid cell lines. This shows that DNA analysis is necessary to
exclude emerin mutations in suspected X-linked EDMD. Emerin levels in
female carriers often deviated from the expected 50% and this was due, in
at least two families, to skewed emerin mRNA expression from the normal and
mutated alleles. In one family with a novel deletion of the last three
exons of the emerin gene, a carrier had a cardiomyopathy and very low
emerin levels (<5% of normal) due to skewed X-inactivation. In the three
autosomal cases of EDMD, emerin was normal on western blots of blood cells,
which suggests that autosomal EDMD is not caused by indirect reduction of
emerin levels.
相似文献
22.
Anxiety during pregnancy and fetal attachment after in-vitro fertilization conception 总被引:3,自引:4,他引:3
McMahon CA; Ungerer JA; Beaurepaire J; Tennant C; Saunders D 《Human reproduction (Oxford, England)》1997,12(1):176-182
The aim of this study was to compare 70 couples who had conceived by in-
vitro fertilization (IVF) with 63 matched controls for the prevalence of
anxiety and quality of attachment to the baby during pregnancy. Results for
mothers showed no group differences using a global measure of anxiety, the
Spielberger State-Trait Anxiety Inventory. However, pregnancy-specific
measures revealed significantly higher levels of anxiety in IVF mothers
about the survival and normality of their unborn babies, about damage to
their babies during childbirth and about separating from their babies after
birth. When IVF mothers were differentiated according to the number of
treatment cycles, more differences in anxiety level were revealed, with
most increases occurring in mothers who had experienced two or more
treatment cycles. IVF fathers did not differ from controls on the global
anxiety measure. No data on pregnancy-specific anxiety were available for
fathers. Neither IVF mothers nor IVF fathers differed from controls on
measures of attachment to the baby during pregnancy. Results are discussed
in the context of the need for researchers to employ differentiated and
issue-specific measures to identify concerns that may be unique to IVF
couples. Clinical implications regarding the need for psychological support
during pregnancy are also discussed.
相似文献
23.
24.
Morphological studies have shown that macrophages and microglia undergo
apoptosis in the central nervous system (CNS) in acute experimental
autoimmune encephalomyelitis (EAE) in the Lewis rat. To assess the relative
levels of macrophage and microglial apoptosis, and the molecular mechanisms
involved in this process, we used three-colour flow cytometry to identify
CD45lowCD11b/c+ microglial cells and CD45highCD11b/c+ macrophages in the
inflammatory cells isolated from the spinal cords of Lewis rats 13 days
after immunization with myelin basic protein (MBP) and complete Freund's
adjuvant. Simultaneously, we analyzed the DNA content of these cell
populations to assess the proportions of cells undergoing apoptosis and in
different stages of the cell cycle or examined their expression of three
apoptosis- regulating proteins, i.e. Fas (CD95), Fas ligand (FasL) and
Bcl-2. Microglia were highly vulnerable to apoptosis and were
over-represented in the apoptotic population. Macrophages were less
susceptible to apoptosis than microglia and underwent mitosis more
frequently than microglia. The different susceptibilities of microglia and
macrophages to apoptosis did not appear to be due to variations in Fas,
FasL or Bcl- 2 expression, as the proportions of microglia and macrophages
expressing these proteins were similar, and were relatively high.
Furthermore, in contrast to T cell apoptosis, apoptosis of
microglia/macrophages did not occur more frequently in cells expressing Fas
or FasL, or less frequently in cells expressing Bcl-2. These results
indicate that the apoptosis of microglia and CNS macrophages in EAE is not
mediated through the Fas pathway, and that Bcl-2 expression does not
protect them from apoptosis. Expression of FasL by macrophages and
microglia may contribute to the pathogenesis and immunoregulation of EAE
through interactions with Fas+ oligodendrocytes and Fas+ T cells. The high
level of microglial apoptosis in EAE indicates that microglial apoptosis
may be an important homeostatic mechanism for controlling the number of
microglia in the CNS following microglial activation and proliferation.
相似文献
25.
目的探讨肝包虫合并乙型肝炎病毒(HBV)感染患者辅助性T细胞17(Th17)、CD4+细胞表面程序性死亡分子-1/程序性死亡分子1配体(PD-1/PD-L1)的表达水平及其临床意义。方法选取2014年9月一2019年9月新疆医科大学第一附属医院收治的肝包虫病患者作为研究对象﹐其中100例肝包虫病合并HBV感染患者为合并HBV感染组,肝包虫病无HBV感染患者88例为非HBV感染组﹐采用流式细胞仪检测外周血Th17,CD4+细胞表面PD-1,PD-L1表达水平。结果合并HBV感染组患者乙型肝炎家族史,B~C Child分级占比均高于非HBV感染组(P<0.05);肝功能指标[谷丙转氨酶(ALT)、谷草转氨酶(AST),γ-谷氨酰转肽酶(γ-GT)]水平以及Th17 PD-1、Th17 PD-L1,CD,PD-1,CD4+PD-L1表达水平均高于非HBV感染组(P<0.05);Child分级A级肝包虫病患者的Th17 PD-1,Th17 PD-L1,CD4+PD-1,CD4+PD-L1表达水平均低于Child分级B~C级患者(P<0.05)。结论HBV感染会影响肝包虫病患者的肝功能及外周血Th17,CD4+细胞表面PD-1,PD-L1表达水平,肝功能严重程度可能与外周血Th17,CD4+细胞PD-1,PD-L1表达存在关系。 相似文献
26.
27.
目的 了解山西省高中生睡眠时间现状及其影响因素。方法 采用分层随机抽样的方法,于2021年5月从山西省117个县(区)各随机抽取一所高中,从高中一、二年级中各随机抽取一个班学生,每个班随机抽取男生女生各17名,共7 956名,采用自编电子问卷进行问卷调查。结果 山西省高中生每日睡眠时间中位数为7.9 h,睡眠不足率为54.0%。性别(OR = 1.138,95%CI:1.032~1.255)、是否近视(OR = 0.798,95%CI:0.711~0.895)、母亲学历(大专或本科:OR = 1.740,95%CI:1.429~2.119)、家庭人均月收入(1 000~1 999元:OR = 0.690,95%CI:0.594~0.802;2 000~3 999元:OR = 0.818,95%CI:0.707~0.947;≥6 000元:OR = 0.681,95%CI:0.544~0.853)、是否参加体育社团(OR = 1.356,95%CI:1.169~1.572)、是否住校(OR = 1.993,95%CI:1.799~2.208)、每周中等强度运动次数(≥5次/周:OR = 1.142,95%CI:1.031~1.264)、中等强度运动时间(31~60 min/次:OR = 0.856,95%CI:0.758~0.966)、每日写作业时间(2~3 h/d:OR = 1.592,95%CI:1.098~2.308;>3 h/d:OR = 1.924,95%CI:1.364~2.716)会影响高中生睡眠时间(P<0.05)。经Hosmer - Lemeshow拟合优度检验,χ2 = 9.100,P>0.05。结论 山西省高中生睡眠不足率相对较高。学校应合理安排学生的作息时间和适当减轻学生的学习负担来保证学生有充足的睡眠时间。 相似文献
28.
OBJECTIVES: To determine the spectrum of N and G genotypes of respiratory syncytial virus (RSV) causing respiratory tract infection and whether particular genotypes are associated with severity of infection. PATIENTS AND METHODS: Nasopharyngeal aspirates (NPAs) were obtained from 114 infants with acute respiratory tract infection due to RSV over two seasons. Viral mRNA was extracted from NPAs or cultured virus, reverse transcribed, and the cDNA amplified by the polymerase chain reaction using primers directed to parts of the N and G gene respectively. Amplicons were separately digested with four different restriction endonucleases for each gene. The fragments were separated by agarose gel, electrophoresis, and the electrophoretic patterns used to assign the various genotypes. Disease severity was assessed as very mild (upper respiratory tract signs only), mild (coryza and signs of lower respiratory tract infection), moderate (requiring nasogastric or intravenous fluids), and severe (requiring oxygen or ventilation). RESULTS: Five of the six known N genotypes were detected, but NP4 and NP2 were found most frequently. There was no association between N genotype and disease severity. Six G (SHL) genotypes were detected. Significantly (p = 0.04) more of the infants infected with the SHL2 genotype had severe or moderate disease. CONCLUSIONS: During the seasonal peaks of RSV respiratory tract infection at least 10 different RSV genotypes cocirculated. While there is no association between N genotypes and disease severity, infection with the SHL2 G genotype appears to result in moderate to severe disease. 相似文献
29.
30.
OBJECTIVE: The purpose of this study was to determine the effect of left-to-right shunting on the resting energy expenditure (REE), total energy expenditure (TEE), and energy intake in a group of 3- to 5-month-old infants with moderate to large unrepaired ventricular septal defects (VSDs) compared with age-matched, healthy infants. METHODS: Eight infants with VSDs and 10 healthy controls between 3 to 5 months of age participated in the study. Indirect calorimetry was used to measure REE and the doubly-labeled water method was used to measure TEE and energy intake. An echocardiogram and anthropometric measurements were performed on all study participants. Daily urine samples were collected at home for 7 days. Samples were analyzed by isotope ratio mass spectrometry. Data were compared using analysis of variance. RESULTS: No significant differences were found in REE (VSD, 42.2 +/- 8.7 kcal/kg/d; control, 43.9 +/- 14.1 kcal/kg/d) or energy intake (VSD, 90.8 +/- 19.9 kcal/kg/d; control, 87.1 +/- 11.7 kcal/kg/d) between the groups. The percent total body water was significantly higher in the VSD infants and the percent fat mass was significantly lower. TEE was 40% higher in the VSD group (VSD, 87.6 +/- 10.8 kcal/kg/d; control, 61.9 +/- 10.3 kcal/kg/d). The difference between TEE and REE, reflecting the energy of activity, was 2.5 times greater in the VSD group. CONCLUSIONS: REE and energy intake are virtually identical between the two groups. Despite this, infants with VSDs have substantially higher TEE than age-matched healthy infants. The large difference between TEE and REE in VSD infants suggests a substantially elevated energy cost of physical activity in these infants. These results demonstrate that, although infants with VSDs may match the energy intake of healthy infants, they are unable to meet their increased energy demands, resulting in growth retardation. 相似文献