全文获取类型
收费全文 | 1695篇 |
免费 | 71篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 27篇 |
儿科学 | 118篇 |
妇产科学 | 105篇 |
基础医学 | 163篇 |
口腔科学 | 74篇 |
临床医学 | 161篇 |
内科学 | 314篇 |
皮肤病学 | 52篇 |
神经病学 | 136篇 |
特种医学 | 60篇 |
外科学 | 230篇 |
综合类 | 31篇 |
预防医学 | 83篇 |
眼科学 | 95篇 |
药学 | 48篇 |
中国医学 | 4篇 |
肿瘤学 | 74篇 |
出版年
2024年 | 4篇 |
2023年 | 19篇 |
2022年 | 36篇 |
2021年 | 43篇 |
2020年 | 43篇 |
2019年 | 67篇 |
2018年 | 60篇 |
2017年 | 46篇 |
2016年 | 63篇 |
2015年 | 48篇 |
2014年 | 78篇 |
2013年 | 93篇 |
2012年 | 113篇 |
2011年 | 112篇 |
2010年 | 63篇 |
2009年 | 63篇 |
2008年 | 128篇 |
2007年 | 144篇 |
2006年 | 124篇 |
2005年 | 97篇 |
2004年 | 101篇 |
2003年 | 75篇 |
2002年 | 81篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 16篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1973年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有1775条查询结果,搜索用时 0 毫秒
81.
Halit Pinar Merielle Stephens Don B. Singer Theonia K. Boyd Solveig M.V. Pflueger David L. Gang Drucilla J. Roberts C. James Sung 《Pediatric and developmental pathology》2002,5(5):495-498
The occurrence of twins, triplets, and other multiple births increased significantly between 1970 and 2000 in the United States
and other industrialized countries. The number of triplet placentas submitted for examination as pathologic specimens has
also markedly increased, but no reference values are published for triplet weights. We examined 196 normal triplet placentas.
Specimens with associated conditions known to affect the weights of the placentas were excluded. The gestational ages ranged
between 20 and 38 weeks. Mean weights for different gestational ages are summarized as follows: 253 g for 20 weeks, 319 g
for 22 weeks, 406 g for 24 weeks, 509 g for 26 weeks, 621 g for 28 weeks, 738 g for 30 weeks, 855 g for 32 weeks, 965 g for
34 weeks, 1065 g for 36 weeks, and 1147 g for 38 weeks. Weight gain of triplet placentas appears to parallel that of twin
placentas. The mean values of placental weights for triplets at each gestational age are less than triple those of singleton
weights for the same duration of gestation. The placental weights in multiple gestations do not increase proportionately with
the number of fetuses. 相似文献
82.
Background: The aim of the present paper was to investigate the relationship between behavioral symptoms and attentional and executive functions and hematological variables related to iron deficiency and anemia, ferritin, hemoglobin, mean corpuscular volume (MCV), and red cell distribution width (RDW) in children and adolescents with attention deficit–hyperactivity disorder (ADHD). Methods: The sample consisted of 52 ADHD children (42 boys, 10 girls; age 7–13 years; mean ± SD, 9.9 ± 2.1 years). Conners Parent and Teacher Rating Scales were obtained. The neuropsychological test battery included Wisconsin Card‐Sorting Test (WCST), Stroop, Continuous Performance Test, Digit Symbol and Digit Span subtests of the Wechsler Intelligence Scale for Children Revised (WISC‐R), and Trail Making Test A and B, which taps abstraction–flexilibity (WCST), sustained attention (CPT), mental tracking and complex attention (WISC‐R Digit Span, Digit Symbol, Trail Making A and B) and interference control (Stroop). Multiple linear regression was used to evaluate the relation of ferritin, hemoglobin, MCV, RDW, age, gender, and presence of comorbidity. Results: While seven children had iron deficiency, none of them was anemic. Lower ferritin levels were associated with higher hyperactivity scores in parental ratings. While performance increased with age for most of the neuropsychological tests utilized, ferritin, hemoglobin, MCV and RDW and gender were not significantly related with cognitive performance in this sample. Conclusions: At least for the present clinical sample, ferritin levels might be related with behavioral but not cognitive measures in ADHD cases. 相似文献
83.
Tanriverdi P Yuksel BC Rasa K Guler G Iskit AB Guc MO Korkmaz A 《The Journal of surgical research》2005,124(1):67-73
BACKGROUND: Circulatory failure in multiple organ dysfunction syndromes (MODS) is characterized with systemic vasodilation, diminished blood flow to various vascular beds. The aim of this study was to investigate the effects of selective inhibition of nitric oxide on the mesenteric arterial blood flow (MABF), survival and organ injury of the liver, kidney, lung and spleen in zymosan-induced MODS. MATERIALS AND METHODS: Forty Swiss albino mice (20-40 g), 7 to 9 weeks old, were obtained. Animals were randomly divided into four groups. The first group were treated intraperitoneally (i.p) with vehicle (saline) and served as a sham group for aminoguanidine (AG) (n=10). The second group was treated with zymosan (500 mg/kg, suspended in saline solution, i.p). The mice in the third and fourth group received AG (15 mg/kg) 1 h and 6 h after zymosan or saline administration, respectively. Eighteen hours after the administration of zymosan, animals were assessed for MODS described subsequently. The signals from the flowmeter were also recorded on mesenteric arterial blood flow values. RESULTS: In zymosan-treated animals, the MABF was significantly lower than that of solvent (saline)-treated controls (ml min(-1), controls: 4.6 +/- 0.6; zymosan: 1.6 +/- 0.9, P <0.05). When animals were treated with AG, there were no significant differences in MABF values between AG group and solvent (saline)-treated control group. However AG prevented zymosan-induced mesenteric MABF decrease. Treatment with aminoguanidine also decreased mortality. CONCLUSION: AG is capable of inhibiting both the induction and the activity of the already iNOS; it remains a potential therapeutic agent in patients with MODS. 相似文献
84.
85.
Subarachnoid hemorrhage (SAH) of spinal origin is a rare entity accounting for approximately 1% of all cases of SAH. Its most frequent causes are trauma and vascular malformations. Although primary spinal tumors, especially ependymomas, are also relatively common causes, SAH secondary to a metastatic spinal tumor arising from outside the central nervous system is an extremely rare condition; only one case has been reported in the literature. The authors present a case of spinal meningeal carcinomatosis secondary to cutaneous malignant melanoma in which the patient presented with only symptoms of SAH. Although very rare, this case underscores several factors. 1) Spinal SAH due to spinal metastases should be considered in the differential diagnosis of patients with previously known malignancy. 2) Spinal SAH may manifest without paraparesis or sensory deficit. 3) Magnetic resonance imaging of the spinal cord may be important to determine the source of SAH in patients in whom four-vessel cerebral angiography demonstrates no abnormal findings. 相似文献
86.
Aytekin FO Tekin K Kabay B Erdem E Guney Y Firat P Sungurtekin U Kaya SO Ozden A 《American journal of surgery》2005,189(2):161-166
BACKGROUND: Mesenteric ischemia-reperfusion (I/R) is a well-known event causing both local and remote organ injuries, including the lungs. Recently, several studies indicated that activated leukocyte-endothelial cell interactions play an important role in the mechanisms of these injuries. As a natural inhibitor of serine proteases, antithrombin was shown previously to attenuate the tissue damage after local I/R in several organ systems. Here, we examined the effects of antithrombin on pulmonary injury after mesenteric I/R. METHODS: Wistar albino rats underwent median laparotomy and were randomized into 3 groups: (1) sham-operated control (n = 12), (2) 60 minutes of mesenteric ischemia and 3 hours of reperfusion (n = 12), and (3) antithrombin-pretreated (250 U/kg) group before the I/R (n = 12). At the end of reperfusion, animals were killed and neutrophil sequestration, myeloperoxidase (MPO) activity, and Evans blue dye extravasation in the lung parenchyma were assessed and compared. RESULTS: There was a statistically significant increase in the quantity of Evans blue dye concentration, leukocyte sequestration, and MPO activity in the I/R group when compared with the control group. The pretreatment of animals with antithrombin significantly decreased the pulmonary injury characterized by increased Evans blue dye extravasation, leukocyte sequestration, and MPO activity. CONCLUSION: The data of the present study suggest that mesenteric ischemia and reperfusion induces pulmonary injury characterized by activated neutrophil sequestration and increased microvascular leakage in the lungs. A significant attenuation of intestinal I/R-related lung injury with the use of antithrombin concentrate warrants further studies to elucidate the potential role of this natural serine protease inhibitor in clinical settings. 相似文献
87.
In this study quality of life perceived by 100 haemodialysis patients with family members' viewpoints on the patients' quality of life was studied. The SF-36 was used as the main measurement tool. According to the findings of the study the quality of life scores, perceived by patients, usually ranged between average and below average. The family members perceived patients' social functioning and functional status in the SF-36 more pessimistically but vitality and well-being in the SF-36 more optimistically, when compared to the patients. In the light of the findings obtained from the study, it is suggested to periodically assess the quality of life of haemodialysis patients considering the viewpoints of family members on the patients' quality of life. 相似文献
88.
OBJECTIVES: We aimed to find the frequency of otolith organ pathologies in the clinical picture of common dizziness etiologies in the chronic stage. METHOD: Subjective visual vertical and subjective visual horizontal measures were assessed in patients who had persistent or recurrent dizziness at least 2 months after the acute period. Every patient was tested in three head positions: neutral, right, or left deviation in the roll plane. Test results were compared with those of the control group. RESULTS: Seventy-three patients and 18 controls were examined. Fifty-eight of the patients had peripheral vestibular disease; 15 of them had central vestibular disease. Left subjective visual horizontal (SVH) and right SVH measures of the peripheral group were significantly different from those of the control group (p < .01). There was no difference in any test between the peripheral and central groups. When we put a cut off point for abnormality (0, 1) according to mean +/- 2 SD of the control group, the peripheral and central groups had very high significant differences from the control group. Approximately 25 to 50% of our patients had pathologic subjective visual vertical or SVH measures according to test type. CONCLUSION: These results showed that the otolith system must be evaluated in the chronic period of dizziness, especially in patients who frequently visit their physician, and modifications in treatment programs must be conducted. 相似文献
89.
Inandi T Bugdayci R Dundar P Sumer H Sasmaz T 《Social psychiatry and psychiatric epidemiology》2005,40(9):725-730
BACKGROUND: The aim of the study was to identify risk factors for depression and to estimate its prevalence in postnatal mothers. METHODS: This cross-sectional and multi-centre study was carried out on 1,350 Turkish women in their first postnatal year. Measures included a structured questionnaire and the Turkish version of the Edinburgh Postnatal Depression Scale (EPDS). RESULTS: Of the women, 31.1% had a score of 13 or higher on the EPDS. The mean score and standard deviation was 9.8+/-5.7. In the multivariate analysis, EPDS scores were significantly associated with economic status, access to support from family members and close friends, emotional distress at the pregnancy, whether the pregnancy was planned, health problems during pregnancy, the perceived standard of baby care after delivery, and mental disorder before and during pregnancy. CONCLUSION: The prevalence of EPDS-based depression among Turkish women in postnatal the period was high, and was associated with several social, economic and demographical factors. 相似文献
90.
Thyroid scintigraphy using Tc-99m pertechnetate is a frequently performed procedure in routine nuclear medicine practice. The indications for thyroid scintigraphy are investigation of hyperthyroidism, nodularity of the gland, cause of thyroid stimulating hormone elevation and localization of an ectopic thyroid gland. In the pediatric population, the most common request is for the evaluation of neonatal hypothyroidism. This imaging procedure is helpful in the identification of the underlying cause as well as in making a differential diagnosis. Early diagnosis is essential for appropriate therapy planning in this age group, and thyroid scintigraphy provides important diagnostic data. This article is written to review the scintigraphic findings in various congenital thyroid anomalies and to underline its use in the differential diagnosis. 相似文献