全文获取类型
收费全文 | 821篇 |
免费 | 83篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 41篇 |
妇产科学 | 14篇 |
基础医学 | 139篇 |
口腔科学 | 47篇 |
临床医学 | 66篇 |
内科学 | 112篇 |
皮肤病学 | 28篇 |
神经病学 | 87篇 |
特种医学 | 126篇 |
外科学 | 98篇 |
综合类 | 13篇 |
预防医学 | 59篇 |
眼科学 | 10篇 |
药学 | 20篇 |
中国医学 | 2篇 |
肿瘤学 | 51篇 |
出版年
2022年 | 2篇 |
2021年 | 9篇 |
2020年 | 11篇 |
2019年 | 13篇 |
2018年 | 24篇 |
2017年 | 9篇 |
2016年 | 10篇 |
2015年 | 15篇 |
2014年 | 22篇 |
2013年 | 34篇 |
2012年 | 24篇 |
2011年 | 28篇 |
2010年 | 29篇 |
2009年 | 30篇 |
2008年 | 18篇 |
2007年 | 34篇 |
2006年 | 28篇 |
2005年 | 25篇 |
2004年 | 23篇 |
2003年 | 23篇 |
2002年 | 25篇 |
2001年 | 20篇 |
2000年 | 28篇 |
1999年 | 21篇 |
1998年 | 34篇 |
1997年 | 45篇 |
1996年 | 37篇 |
1995年 | 26篇 |
1994年 | 22篇 |
1993年 | 19篇 |
1992年 | 16篇 |
1991年 | 19篇 |
1990年 | 23篇 |
1989年 | 34篇 |
1988年 | 17篇 |
1987年 | 18篇 |
1986年 | 10篇 |
1985年 | 16篇 |
1984年 | 7篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 2篇 |
1980年 | 11篇 |
1978年 | 3篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1968年 | 3篇 |
排序方式: 共有923条查询结果,搜索用时 15 毫秒
1.
The human visual system is amenable to a number of adaptive processes; one such process, or collection of processes, is the adaptation to blur. Blur adaptation can be observed as an improvement in vision under degraded conditions, and these changes occur relatively rapidly following exposure to blur. The potential important future directions of this research area and the clinical implications of blur adaptation are discussed. 相似文献
2.
Light emitting diodes for auramine O fluorescence microscopic screening of Mycobacterium tuberculosis. 总被引:1,自引:0,他引:1
R M Anthony A H J Kolk S Kuijper P R Klatser 《The international journal of tuberculosis and lung disease》2006,10(9):1060-1062
We describe the simple adaptation of a standard fluorescent microscope for illumination using a 'Royal Blue' Luxeon light emitting diode (LED) and demonstrate that this form of illumination is suitable for the detection of auramine O stained Mycobacterium spp. The low cost, low power consumption, safety and reliability of LEDs makes them attractive alternatives to mercury vapour lamps. 相似文献
3.
4.
Hausegger KA; Cragg AH; Lammer J; Lafer M; Fluckiger F; Klein GE; Sternthal MH; Pilger E 《Radiology》1994,190(1):199
5.
Serum ionic fluoride levels in haemodialysis and continuous ambulatory peritoneal dialysis patients 总被引:1,自引:1,他引:0
al-Wakeel JS; Mitwalli AH; Huraib S; al-Mohaya S; Abu-Aisha H; Chaudhary AR; al-Majed SA; Memon N 《Nephrology, dialysis, transplantation》1997,12(7):1420-1424
High serum fluoride (F-) in patients with chronic renal failure (CRF) and
end-stage renal disease (ESRD) is associated with risk of renal
osteodystrophy and other bone changes. This study was done to determine F-
in normal healthy controls and patients with ESRD on haemodialysis (HD) or
peritoneal dialysis (PD). Seventeen healthy controls (12 males, 5 females)
and 39 ESRD patients on dialysis (17 males, 22 females) were recruited in
the study in a community with 47.4 +/- 3.28 microM/l (range 44-51 microM/l)
of F- content in drinking water. Control subjects showed a mean serum F-
concentration of 1.08 +/- 0.350 microM/l. Males in control group showed
slightly higher F- levels (1.15 +/- 0.334, range 0.55-1.9 microM/l) than
females (0.92 +/- 0.370, range 0.6-1.5 microM/l). Mean serum F-
concentration did not correlate significantly with age and sex among
control subjects, whereas such correlation was observed in patients with
ESRD on dialysis. Mean serum F- concentration was significantly higher in
patients on dialysis (2.67 +/- 1.09, range 0.8-5.2 microM/l) than normal
controls. When grouped according to sex, the mean serum F- concentration in
males (3.05 +/- 1.04, range 1.8-5.2 microM/l) was significantly higher than
females (2.38 +/- 1.08, range 0.8-5.2 microM/l). When patients were grouped
according to age, it was observed that F- concentration was significantly
higher in patients with age groups 21-70 (2.86 +/- 1.05) than those with
age group 13-20 years (1.42 +/- 0.531). Thus F- concentration correlated
with age and sex, being higher in males and above 20 years. Despite
appreciable clearance of F- (39-90%) across the peritoneum, patients on
CAPD showed higher serum F- concentration than those on HD (3.1 +/- 1.97 vs
2.5 +/- 1.137 microM/l). Of the total 39 patients on dialysis 39% had their
serum F- concentration above 3.0 microM/l, posing the risk of renal
osteodystrophy.
相似文献
6.
Focal liver lesions: characterization with triphasic spiral CT 总被引:15,自引:1,他引:14
7.
Characteristics of wheeze during histamine-induced airways obstruction in children with asthma.
下载免费PDF全文
![点击此处可从《Thorax》网站下载免费的PDF全文](/ch/ext_images/free.gif)
S. Rietveld E. H. Dooijes L. H. Rijssenbeek-Nouwens F. Smit P. J. Prins A. M. Kolk W. A. Everaerd 《Thorax》1995,50(2):143-148
BACKGROUND--An automated system has been developed for the detection of sound patterns suggestive of airways obstruction in long term recordings. The first step, presented here, was tracheal sound recording during histamine-induced airways obstruction. METHODS--The tracheal sounds of 29 children aged 8-19 years with asthma were recorded during airways obstruction caused by histamine inhalation using a system for continuous respiratory telemetry and computer analysis. Sound patterns were analysed, classified, and related to airways obstruction measured by lung function tests based on the forced expiratory volume in one second (FEV1). RESULTS--Five sound patterns were identified, one dominant sensitive and four specific to a fall in FEV1 of > 20%. The presence of at least one of three specific sound patterns during unforced respiration predicted a fall in FEV1 of > 20% in 87.5% of the subjects. The inspiratory and expiratory sound patterns were almost equally informative of airways obstruction. CONCLUSIONS--Wheezes can be differentiated with more precision than is currently accepted. Tracheal sound patterns are sensitive and specific predictors of histamine-induced airways obstruction. These patterns are neither invariably nor proportionally related to the results of lung function testing. However, they can be used for detection of airways obstruction on the basis of their presence or absence. 相似文献
8.
B A van der Kolk 《Psychiatric Clinics of North America》1989,12(2):389-411
Trauma can be repeated on behavioral, emotional, physiologic, and neuroendocrinologic levels. Repetition on these different levels causes a large variety of individual and social suffering. Anger directed against the self or others is always a central problem in the lives of people who have been violated and this is itself a repetitive re-enactment of real events from the past. People need a "safe base" for normal social and biologic development. Traumatization occurs when both internal and external resources are inadequate to cope with external threat. Uncontrollable disruptions or distortions of attachment bonds precede the development of post-traumatic stress syndromes. People seek increased attachment in the face of external danger. Adults, as well as children, may develop strong emotional ties with people who intermittently harass, beat, and threaten them. The persistence of these attachment bonds leads to confusion of pain and love. Assaults lead to hyperarousal states for which the memory can be state-dependent or dissociated, and this memory only returns fully during renewed terror. This interferes with good judgment about these relationships and allows longing for attachment to overcome realistic fears. All primates subjected to early abuse and deprivation are vulnerable to engage in violent relationships with peers as adults. Males tend to be hyperaggressive, and females fail to protect themselves and their offspring against danger. Chronic physiologic hyperarousal persists, particularly to stimuli reminiscent of the trauma. Later stresses tend to be experienced as somatic states, rather than as specific events that require specific means of coping. Thus, victims of trauma may respond to contemporary stimuli as a return of the trauma, without conscious awareness that past injury rather than current stress is the basis of their physiologic emergency responses. Hyperarousal interferes with the ability to make rational assessments and prevents resolution and integration of the trauma. Disturbances in the catecholamine, serotonin, and endogenous opioid systems have been implicated in this persistence of all-or-none responses. People who have been exposed to highly stressful stimuli develop long-term potentiation of memory tracts that are reactivated at times of subsequent arousal. This activation explains how current stress is experienced as a return of the trauma; it causes a return to earlier behavior patterns. Ordinarily, people will choose the most pleasant of two alternatives. High arousal causes people to engage in familiar behavior, regardless of the rewards. As novel stimuli are anxiety provoking, under stress, previously traumatized people tend return to familiar patterns, even if they cause pain.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
9.
Changes in Avidity and Level of Immunoglobulin G Antibodies to Mycobacterium tuberculosis in Sera of Patients Undergoing Treatment for Pulmonary Tuberculosis
下载免费PDF全文
![点击此处可从《Clinical and Vaccine Immunology : CVI》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Lenka M. Pereira Arias-Bouda Sjoukje Kuijper Anouk Van Der Werf Lan N. Nguyen Henk M. Jansen Arend H. J. Kolk 《Clinical and Vaccine Immunology : CVI》2003,10(4):702-709
Much is known about specific antibodies and their titers in patients with tuberculosis. However, little is known about the avidity of these antibodies or whether changes in avidity occur during the progression of the disease or during treatment. The aims of this study were to determine the avidity of antibodies to Mycobacterium tuberculosis in patients with pulmonary tuberculosis, to explore the value of avidity determination for the diagnosis of tuberculosis, and to study changes in levels of antibodies and their avidity during treatment. Antibody avidity was measured by an enzyme-linked immunosorbent assay with thiocyanate elution. Avidity indices and serum levels of immunoglobulin G to M. tuberculosis were determined for 22 patients with pulmonary tuberculosis before and during treatment and for 24 patients with other pulmonary diseases. Antibody levels and avidity were both significantly higher in untreated tuberculosis patients than in the controls. Avidity determination had more diagnostic potential than determination of the antibody levels. Tuberculosis patients with a long duration of symptoms had higher antibody avidity than those with a recent onset of symptoms, indicating affinity maturation of specific antibodies during active disease. In the early phase of treatment, a decrease in antibody avidity was observed for 73% of all tuberculosis patients, accompanied by an initial increase in antibody levels in 36% of these patients. These phenomena could be explained by an intense stimulation of the humoral response by antigens released from killed bacteria, reflecting early bactericidal activity of antituberculous drugs leading to the production of low-affinity antibodies against these released antigens. 相似文献
10.
Metabolic adaptation of the chick embryo to chronic hypoxia 总被引:1,自引:0,他引:1