全文获取类型
收费全文 | 24452篇 |
免费 | 1808篇 |
国内免费 | 83篇 |
学科分类
医药卫生 | 26343篇 |
出版年
2024年 | 33篇 |
2023年 | 272篇 |
2022年 | 417篇 |
2021年 | 1104篇 |
2020年 | 728篇 |
2019年 | 1023篇 |
2018年 | 1054篇 |
2017年 | 763篇 |
2016年 | 770篇 |
2015年 | 998篇 |
2014年 | 1252篇 |
2013年 | 1501篇 |
2012年 | 2248篇 |
2011年 | 2230篇 |
2010年 | 1227篇 |
2009年 | 954篇 |
2008年 | 1550篇 |
2007年 | 1460篇 |
2006年 | 1311篇 |
2005年 | 1152篇 |
2004年 | 957篇 |
2003年 | 750篇 |
2002年 | 651篇 |
2001年 | 264篇 |
2000年 | 214篇 |
1999年 | 199篇 |
1998年 | 120篇 |
1997年 | 92篇 |
1996年 | 76篇 |
1995年 | 60篇 |
1994年 | 61篇 |
1993年 | 58篇 |
1992年 | 82篇 |
1991年 | 72篇 |
1990年 | 63篇 |
1989年 | 57篇 |
1988年 | 48篇 |
1987年 | 45篇 |
1986年 | 32篇 |
1985年 | 39篇 |
1984年 | 36篇 |
1983年 | 27篇 |
1982年 | 20篇 |
1980年 | 23篇 |
1975年 | 22篇 |
1973年 | 25篇 |
1970年 | 16篇 |
1968年 | 17篇 |
1967年 | 15篇 |
1966年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
71.
72.
Janine A Danks Patricia M W Ho Amanda J Notini Frosa Katsis Peter Hoffmann Bruce E Kemp T John Martin Jeffrey D Zajac 《Journal of bone and mineral research》2003,18(7):1326-1331
A PTH gene has been isolated from the fish Fugu rubripes. The encoded protein of 80 amino acid has the lowest homology with any of the PTH family members. Fugu PTH(1-34) had 5-fold lower potency than human PTH(1-34) in a mammalian cell system. INTRODUCTION: Parathyroid hormone (PTH) is the major hypercalcemic hormone in higher vertebrates. Fish lack parathyroid glands, but there have numerous attempts to identify and isolate PTH from fish. MATERIALS AND METHODS: Polymerase chain reaction (PCR) was performed with primers based on preliminary data from the Joint Genome Institute database. PCR amplification was performed on genomic DNA isolated from Fugu rubripes. PCR products were purified and DNA was sequenced. All sequence was confirmed from more than one independently amplified PCR product. Multiple sequence alignments were carried out, and the percentage of identities and similarities were calculated. An unrooted phylogenetic tree, using all the known PTH and PTH-related protein (PTHrP) amino acid sequences, was determined. Synthetic peptides were tested in a biological assay that measured cyclic adenosine 3',5'-monophosphate formation in UMR106.1 cells. Rabbit polyclonal antisera specific for N-terminal human PTHrP and one rabbit polyclonal antiserum specific for N terminus hPTH were used to test the cross-reactivity with fPTH(1-34) in immunoblots. 相似文献
73.
74.
The effect of oral appliance therapy on blood pressure in patients with obstructive sleep apnea 总被引:1,自引:1,他引:0
Ryo Otsuka Fernanda Ribeiro de Almeida Alan A. Lowe Wolfgang Linden Frank Ryan 《Sleep & breathing》2006,10(1):29-36
The objective of the study was to investigate the effects of oral appliance (OA) therapy on ambulatory blood pressure in patients
with obstructive sleep apnea (OSA). Eleven OSA patients who received OA therapy were prospectively investigated. Ambulatory
blood pressure was measured for 20 h from 4:00 p.m. to 12:00 noon the next day using an ambulatory blood pressure monitor. The Respiratory Disturbance Index (RDI) was measured
in the pretreatment and posttitration periods. The OA was titrated to reach a therapeutic jaw position over 2 to 8 months,
and posttitration measurements were repeated. At posttitration, the RDI was significantly decreased from a mean (SD) of 24.7
(20.1) to 6.1 (4.5). Significant reductions in diastolic blood pressure (DBP) and mean arterial pressure (MAP) were found
for the 20-h periods, and systolic blood pressure (SBP), DBP, and MAP while asleep. The mean values were 79.5 (5.5) to 74.6
(6.0) for DBP and 95.9 (5.4) to 91.2 (5.9) for MAP, for over a 20-h period, and 118.4 (10.0) to 113.7 (9.1) for SBP, 71.6
(8.0) to 67.2 (7.9) for DBP, and 88.4 (8.0) to 83.9 (7.5) for MAP, while asleep. This study suggests that successful OSA treatment
with an OA may also be beneficial to lower blood pressure in OSA patients, as previously suggested for nasal continuous positive
airway pressure therapy.
This study was conducted in the Division of Orthodontics, The University of British Columbia, Canada 相似文献
75.
B M Almeida S J Challacombe J W Eveson C G Smith I M Leigh 《The Journal of pathology》1992,166(3):243-253
The murine monoclonal antibody, LH39 was characterized in this study and appeared to bind to a novel basement membrane epitope. This antigen was expressed in the epithelial basement membrane of human tissue derived from all three germ cell layers and in basement membranes surrounding small blood vessels within the stroma of all organs examined. LH39 antigen could be first detected in fetal skin at the dermo-epidermal junction at 7 weeks estimated gestational age but was not present in the dermal vasculature until 16 weeks. When tested against tissue from a range of lower mammalian species, LH39 antigen appeared to be primate-specific. The epithelial basement membrane zone in organotypical cultures, where there is de novo synthesis of basement membrane components, contained abundant LH39 antigen in contrast to other basement membrane components, type IV collagen, laminin, and type VII collagen. Ultrastructural localization of LH39 epitope, using immunogold electron microscopy on unfixed freshly frozen tissue, was to the lamina lucida. No cross-reactivity could be detected between LH39 and laminin, fibronectin, and collagens I, III, IV, and V using the ELISA assay. In vitro studies with a range of proteolytic enzymes suggested that the antigen was non-collagenous in nature. LH39 precipitated a polypeptide with a molecular weight of 185 kD from extracts of metabolically labelled cultured keratinocytes, and polypeptides of 185 and 200 kD from the culture medium. The tissue distribution of LH39 antigen suggested that it may be an epitope within anchoring filaments. Potential applications of this antibody include the study of benign and malignant human vascular disorders, diseases and tumours associated with angiogenesis, epithelial neoplasms, and conditions of tissue regeneration and repair, such as wound healing. 相似文献
76.
A. Queirós J. M. González-Méijome P. Fernandes J. Jorge J. B. Almeida M. A. Parafita 《Ophthalmic & physiological optics》2006,26(4):384-391
PURPOSE: The main objectives of this study were to determine the differences between non-synchronized intraocular pressure (IOP_N) and intraocular pressure readings synchronized with cardiac pulse and try to determine if these parameters are related to blood pressure values. METHODS: One hundred and sixty-five right eyes from 165 volunteers (107 females, 58 males) aged from 19 to 73 years (mean +/- S.D., 29.93 +/- 11.17) were examined with the Nidek NT-4000, a new non-contact tonometer that allows the measurement of IOP synchronized with the cardiac rhythm. IOP measurements in the four different modes of synchronization were taken in a randomized order. Three measures of each parameter were taken and then averaged. The blood pressure was determined three times with a portable manometer and mean values of systolic and diastolic pressure and the pulse rate were computed. Mean arterial pressure (MAP) was determined as being 1/3 of systolic plus 2/3 of diastolic blood pressure. RESULTS: The mean +/- S.D. values for the standard intraocular pressure (IOP_N: 14.76 +/- 2.86), intraocular pressure in the systolic instant or peak (IOP_P: 14.99 +/- 2.85), intraocular pressure in the middle instant between heartbeats or middle (IOP_M: 14.68 +/- 2.76), and intraocular pressure in the diastolic instant or bottom (IOP_B: 13.86 +/- 2.61) were obtained. The IOP_P was higher than the remaining values. A significant difference in mean IOP existed between IOP_B and the remaining modes of measuring (p < 0.05). Differences were statistically significant for all pair comparisons involving IOP_B. Arterial blood pressure values were systolic 125.5 +/- 14.22, diastolic 77.7 +/- 8.38 and MAP 93.64 +/- 9.44 mmHg. The pulse rate was 77.3 +/- 12.6 beats per minute. Except for the MAP (p = 0.025) there was no significant correlation between different IOP values and systolic or diastolic blood pressure, or pulse rate. CONCLUSIONS: NT-4000 is able to differentiate IOP values when synchronized with the cardiac rhythm and those differences are expected to be within a range of +/-2.5 to +/- 3.0 mmHg. IOP_B seems to be the parameter whose value differs from the non-synchronized and the remaining synchronized parameters in a significant way. Other than a weak association with MAP, no significant correlation between IOP and BP was found. The measurements of IOP readings for the three modes are consistent with timings during the cardiac cycle and IOP pulse cycle. 相似文献
77.
78.
Lee L. Eckhardt MD Amanda L. Farley MS Esther Rodriguez MD Karen Ruwaldt BS Daniel Hammill David J. Tester BS Michael J. Ackerman MD PhD Jonathan C. Makielski MD 《Heart rhythm》2007,4(3):323-329
BACKGROUND: Loss-of-function mutations in the KCNJ2 cause approximately 50% of Andersen-Tawil Syndrome (ATS) characterized by a classic triad of periodic paralysis, ventricular arrhythmia, and dysmorphic features. Do KCNJ2 mutations occur in patients lacking this triad and lacking a family history of ATS? OBJECTIVES: The purpose of this study was to identify and characterize mutations in the KCNJ2-encoded inward rectifier potassium channel Kir2.1 from patients referred for genetic arrhythmia testing. METHODS: Mutational analysis of KCNJ2 was performed for 541 unrelated patients. The mutations were made in wild type (WT) and expressed in COS-1 cells and voltage clamped for ion currents. RESULTS: Three novel missense mutations (R67Q, R85W, and T305A) and one known mutation (T75M) were identified in 4/249 (1.6%) patients genotype-negative for other known arrhythmia genes with overall incidence 4/541 (0.74%). They had prominent U-waves, marked ventricular ectopy, and polymorphic ventricular tachycardia but no facial/skeletal abnormalities. Periodic paralysis was present in only one case. Outward current was decreased to less than 5% of WT for all mutants expressed alone. Co-expression with WT (simulating heterozygosity) caused a marked dominant negative effect for T75M and R82W, no dominant negative effect for R67Q, and a novel selective enhancement of inward rectification for T305A. CONCLUSIONS: KCNJ2 loss of function mutations were found in approximately 1% of patients referred for genetic arrhythmia testing that lacked criteria for ATS. Characterization of three new mutations identified a novel dominant negative effect selectively reducing outward current for T305A. These results extend the range of clinical phenotype and molecular phenotype associated with KCNJ2 mutations. 相似文献
79.
Mariela Dutra Gontijo Moura Tatiane Roberta Morais Guimar?es Linaena Méricy Silva Fonseca Isabela de Almeida Pordeus Ricardo Alves Mesquita 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2007,103(1):64-71
OBJECTIVE: The objective of this study was to assess the efficiency of topical applications of podophyllin resin (25%) (P) versus podophyllin resin (25%) together with acyclovir cream (5%) (PA) in the treatment of oral hairy leukoplakia (OHL) in accordance with the following criteria: (1) number of applications necessary for the total clinical resolution of OHL; (2) correlation between the decrease of lesion size and the number of applications; (3) total clinical resolution of OHL; and (4) clinical reevaluation 12 months after the end of treatment. STUDY DESIGN: Forty-six OHLs were treated with P (P group) or with PA (PA group). Applications were performed weekly. Student t, Fisher exact, and Pearson correlation tests were used for statistical analysis. RESULTS: All 24 lesions from the PA group presented total clinical resolution while 4 lesions from the P group did not. The P group required up to 25 applications performed weekly while the PA group required up to 18. Observed was a negative significant association between the size of the lesions and the number of applications performed weekly in the PA group. CONCLUSIONS: The present study demonstrated the following: (1) P and PA topical treatments presented a similar average number of applications performed weekly; (2) both groups showed the same clinical response at 12 months post-therapy; and (3) PA presented a 100% clinical resolution and a continuous decrease in OHL size over the course of weekly applications. 相似文献
80.
Sergio Luís Blay Sergio Baxter Andreoli Fábio Leite Gastal 《Annals of clinical psychiatry》2007,19(3):169-174
BACKGROUND: The main purpose of this study is to investigate the association of disturbed sleep, chronic physical pain and psychiatric morbidity in people aged 60 years and over. METHODS: A population-based random sample of 7040 household residents aged 60 years and over, was examined in a face-to-face interview. Painful medical conditions were assessed through questions evaluating medical treatment, hospitalizations, and consultations for medical problems. Disturbed sleep was assessed through questions concerning the presence of sleeping problems in the past 4 weeks. RESULTS: The overall prevalence of disturbed sleep is 33.7% (95% CI: 32.5-34.8) and the 6-month prevalence of any chronic pain was 76.2% (95% CI: 74.2-78.2%). A substantial burden of disturbed sleep is associated with the presence of physical pain morbidity, 42.5% for back pain to 49.7% for headaches. The prevalence of pain among persons with disturbed sleep ranges from 25.8% for gastrointestinal pain to 54.6% for joint pain. The presence of comorbid pain and disturbed sleep has an important disability impact as assessed by socioecomomic/professional data, health care utilization, self-rated health and physical activity. In logistic regression models, headaches, psychiatric morbidity, rural origin, Caucasians, self-rated health and number of chronic pain conditions were significantly associated with disturbed sleep after controlling for demographic variables and comorbidities. Age has a negative effect on sleep complaints. CONCLUSIONS: Disturbed sleep is highly comorbid with other pain conditions particularly headaches and psychiatric morbidity in later life. The combination of pain and disturbed sleep leads to important role disability and increased utilization of medical services. 相似文献