全文获取类型
收费全文 | 47046篇 |
免费 | 3286篇 |
国内免费 | 298篇 |
专业分类
耳鼻咽喉 | 260篇 |
儿科学 | 1437篇 |
妇产科学 | 847篇 |
基础医学 | 4209篇 |
口腔科学 | 818篇 |
临床医学 | 3687篇 |
内科学 | 6499篇 |
皮肤病学 | 673篇 |
神经病学 | 2707篇 |
特种医学 | 1259篇 |
外科学 | 5305篇 |
综合类 | 10047篇 |
一般理论 | 22篇 |
预防医学 | 8389篇 |
眼科学 | 324篇 |
药学 | 2100篇 |
38篇 | |
中国医学 | 1239篇 |
肿瘤学 | 770篇 |
出版年
2024年 | 99篇 |
2023年 | 677篇 |
2022年 | 1198篇 |
2021年 | 1647篇 |
2020年 | 1411篇 |
2019年 | 3513篇 |
2018年 | 3031篇 |
2017年 | 1926篇 |
2016年 | 1074篇 |
2015年 | 1114篇 |
2014年 | 2722篇 |
2013年 | 2593篇 |
2012年 | 2474篇 |
2011年 | 2635篇 |
2010年 | 2132篇 |
2009年 | 1891篇 |
2008年 | 1713篇 |
2007年 | 1574篇 |
2006年 | 1431篇 |
2005年 | 1001篇 |
2004年 | 800篇 |
2003年 | 641篇 |
2002年 | 459篇 |
2001年 | 383篇 |
2000年 | 337篇 |
1999年 | 290篇 |
1998年 | 233篇 |
1997年 | 217篇 |
1996年 | 162篇 |
1995年 | 163篇 |
1994年 | 145篇 |
1993年 | 84篇 |
1992年 | 49篇 |
1991年 | 44篇 |
1990年 | 40篇 |
1988年 | 32篇 |
1986年 | 33篇 |
1985年 | 865篇 |
1984年 | 1393篇 |
1983年 | 1113篇 |
1982年 | 1103篇 |
1981年 | 1107篇 |
1980年 | 955篇 |
1979年 | 847篇 |
1978年 | 660篇 |
1977年 | 466篇 |
1976年 | 634篇 |
1975年 | 554篇 |
1974年 | 469篇 |
1973年 | 430篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Implicit memory is independent from IQ and age but not from etiology: evidence from Down and Williams syndromes 总被引:1,自引:0,他引:1
S. Vicari L. Verucci & G. A. Carlesimo 《Journal of intellectual disability research : JIDR》2007,51(12):932-941
Background In the last few years, experimental data have been reported on differences in implicit memory processes of genetically distinct groups of individuals with Intellectual Disability (ID). These evidences are relevant for the more general debate on supposed asynchrony of cognitive maturation in children with abnormal brain development. This study, comparing implicit memory processes in individuals with Williams syndrome (WS) and Down syndrome (DS), was planned to verify the ‘etiological specificity’ hypotheses pertaining to the skill learning abilities of individuals with ID. Method A modified version of Nissen and Bullemer's (1987) Serial Reaction Time (SRT) task was used. The performances of three group were evaluated. The first group consisted of thirty‐two people with WS (18 males and 14 females). The second group was comprised of twenty‐six individuals with DS (14 males and 12 females). The two groups of individuals with ID were selected so that the groups were comparable as for mental age and chronological age. The third group consisted of forty‐nine typically developed children with a mental age similar to that of the groups with WS and DS. Results The two groups of individuals with ID demonstrated different patterns of procedural learning. WS individuals revealed poor implicit learning of the temporal sequence of events characterizing the ordered blocks in the SRT task. Indeed, differently from normal controls, WS participants showed no reaction time (RT) speeding through ordered blocks. Most importantly, the rebound effect, which so dramatically affected normal children's RTs passing from the last ordered to the last block, had only a marginal influence on WS children's RTs. Differently from the WS group, the rate of procedural learning of the participants with DS was comparable to that of their controls. Indeed, DS and typically developed individuals showed parallel RT variations in the series of ordered blocks and, more importantly, passing from the last ordered to the last block. Therefore, a substantial preservation of skill learning abilities in this genetic syndrome is confirmed. Conclusions The results of the present study document that procedural learning in individuals with ID depends on the aetiology of the syndrome, thus supporting the etiological specificity account of their cognitive development. These results are relevant for our knowledge about the qualitative aspects and the underlying neurobiological substrate of the anomalous cognitive development in mentally retarded people. 相似文献
102.
103.
Purpose For tissue characterization of the arterial wall, we developed a “phased tracking” method to measure the strain (change in
wall thickness) and elasticity of the arterial wall. To improve the accuracy of tissue characterization, we are now attempting
to measure other mechanical properties in addition to elasticity.
Methods In this study, the change in elasticity during the cardiac diastole was measured with ultrasound by generating a change in
internal pressure using remote cyclic actuation.
Results From the measured change in elasticity during cardiac diastole, the nonlinear property in the stress–strain relationship of
the artery wall was estimated. In basic experiments using a silicone rubber tube and in vivo experiments in human carotid
arteries.
Conclusion The proposal method enables the noninvasive measurement of the nonlinear mechanical property in addition to the elasticity
of the arterial wall. 相似文献
104.
105.
A. J. Esbensen M. M. Seltzer & J. S. Greenberg 《Journal of intellectual disability research : JIDR》2007,51(12):1039-1050
Background Little is known about the mortality of individuals with Down syndrome who have lived at home with their families throughout their lives. The current study evaluates the predictors, causes and patterns of mortality among co‐residing individuals in midlife with Down syndrome as compared with co‐residing individuals with ID owing to other causes. Method This paper examines mortality in 169 individuals with and 292 individuals without Down syndrome from 1988 to 2007. Dates and causes of death were obtained from maternal report, the Social Security Death Index and the National Death Index. Risk factors predicting mortality, including demographic variables, transition variables, and initial and change measures of health, functional abilities and behaviour problems, were obtained from maternal report. Results Having Down syndrome is a risk factor of mortality, net of other risk factors including older age, poorer functional abilities, worsening behaviour problems, residential relocation and parental death. The causes of death among individuals with and without Down syndrome who are in midlife and co‐residing with their families are similar, and are most commonly due to cardiovascular or respiratory problems. Conclusions The findings indicate that midlife adults with Down syndrome who co‐reside with their families generally exhibit similar causes of mortality as do midlife adults with intellectual disability owing to other causes, but show an elevated risk of mortality in midlife net of other variables, such as age and changes in functional abilities and behaviour problems. 相似文献
106.
H. Kitamura T. Shioiri M. Itoh Y. Sato K. Shichiri & T. Someya 《Journal of intellectual disability research : JIDR》2007,51(10):812-820
Background Evidence suggests that, as a group, patients with schizophrenia have intellectual deficits that may precede the manifestation of psychotic symptoms; however, how successfully intelligence tests are able to discriminate schizophrenia from other psychotic disorders has yet to be investigated in detail. Methods Using Wechsler Adult Intelligence Scale – Revised (WAIS‐R) data for 55 inpatients with schizophrenia and 28 inpatients with non‐schizophrenic psychotic disorders (NSPD) (schizophreniform disorder, brief psychotic disorder, delusional disorder, psychotic disorder due to a general medical condition, and psychotic disorders not otherwise specified), intelligence performance was compared between schizophrenia and NSPD and among different subtypes of schizophrenia. Results There were no significant differences in intelligence quotient (IQ), verbal IQ (VIQ) and performance IQ (PIQ) discrepancy, and subtest scores of WAIS‐R between the patients with schizophrenia and those with NSPD. These diagnostic groups were not discriminated well by any WAIS‐R variables. Schizophrenia patients with prominent negative symptoms, on the other hand, had a significantly larger IQ discrepancy (VIQ > PIQ) than those without prominent negative symptoms and NSPD patients. Intelligence performance in schizophrenia did not differ with respect to diagnostic subtypes and longitudinal courses. Conclusions The current study failed to show diagnostic usefulness of WAIS‐R in discriminating schizophrenia and other psychoses. A diagnosis of schizophrenia does not significantly impact intellectual deficits in psychotic disorders. 相似文献
107.
C Yimin Y Wei C Weidong W Xianmi W Junqing L Lin 《International journal of gynaecology and obstetrics》2004,84(3):229-235
OBJECTIVES: To assess the effect of a medically induced abortion (MA) on birth weight in the first subsequent pregnancy. METHODS: Pregnant women who had had a MA, a surgical abortion (SA), or primigravidas with no history of abortion (NA), were recruited for a prospective cohort study between July 1998 and February 2001. The sample for the present analysis included 12995 singleton live births at term. RESULTS: The overall incidence rate of low birth weight (LBW) was 1.0%. The rates of LBW in the MA, SA, and NA groups were 1.0%, 0.9%, and 1.2, respectively. There were no significant differences in LBW rates between the MA and SA groups, neither between the MA and NA. Logistic regression analysis was used to estimate the effects of MA on birth weight, and we found no relationship between risk of LBW and MA. CONCLUSIONS: We did not find a statistically significant relationship between a history of one medically induced abortion and LBW for the first subsequent term pregnancy. 相似文献
108.
医院管理不是孤立自存的现象,由于管理者和被管理都生活在一定的医院文化氛围之中,因此,医院文化的哲学内核是现代医院管理知识的精髓,医院组织的价值观念、道德准则和思维方式,深刻地影响和制约着现代医院管理的原则和方法,决定着现代医院管理的实施和成败。 相似文献
109.
不断强化医务人员的服务意识是消除医患纠纷的首要条件,认真培养敬业精神是避免医患纠纷的根本途径;提高道德境界是避免医患纠纷的决定因素. 相似文献
110.
Unsteady Fluid Dynamics of Several Mechanical Prosthetic Heart Valves Using a Two Component Laser Doppler Anemometer System 总被引:5,自引:0,他引:5
Abstract: Five typical mechanical heart valves (Starr-Edwards, Björk-Shiley convexo-concave (c-c), Björk-Shiley monostrut, Bicer-Val, and St. Jude Medical) were tested in the mitral position under the pulsatile flow condition. The test program included measurements of velocity and turbulent stresses at 5 downstream locations. The study was carried out using a sophisticated cardiac simulator in conjunction with a highly sensitive 2 component laser Doppler anemometer (LDA) system. The continuous monitoring of parametric time histories revealed useful details about the complex flow and helped to establish the locations and times of the peak parameter values. Based upon the nondimensional presentation of data, the following general conclusions can be made. First, all the 5 valve designs created elevated turbulent stresses during the accelerating and peak flow phases, presenting the possibility of thromboembolism and perhaps hemolysis. Second, the difference in valve configuration seemed to affect the flow characteristics; third, the bileaflet design of the St. Jude valve appeared to create a lower turbulence stress level. 相似文献