全文获取类型
收费全文 | 2698篇 |
免费 | 212篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 114篇 |
妇产科学 | 66篇 |
基础医学 | 391篇 |
口腔科学 | 70篇 |
临床医学 | 244篇 |
内科学 | 544篇 |
皮肤病学 | 29篇 |
神经病学 | 165篇 |
特种医学 | 466篇 |
外科学 | 288篇 |
综合类 | 61篇 |
预防医学 | 161篇 |
眼科学 | 68篇 |
药学 | 93篇 |
1篇 | |
肿瘤学 | 139篇 |
出版年
2021年 | 15篇 |
2020年 | 16篇 |
2019年 | 25篇 |
2018年 | 26篇 |
2017年 | 31篇 |
2016年 | 23篇 |
2015年 | 28篇 |
2014年 | 47篇 |
2013年 | 71篇 |
2012年 | 69篇 |
2011年 | 83篇 |
2010年 | 63篇 |
2009年 | 76篇 |
2008年 | 80篇 |
2007年 | 93篇 |
2006年 | 91篇 |
2005年 | 80篇 |
2004年 | 75篇 |
2003年 | 65篇 |
2002年 | 52篇 |
2001年 | 67篇 |
2000年 | 67篇 |
1999年 | 67篇 |
1998年 | 100篇 |
1997年 | 92篇 |
1996年 | 96篇 |
1995年 | 77篇 |
1994年 | 66篇 |
1993年 | 74篇 |
1992年 | 57篇 |
1991年 | 56篇 |
1990年 | 60篇 |
1989年 | 80篇 |
1988年 | 75篇 |
1987年 | 77篇 |
1986年 | 81篇 |
1985年 | 87篇 |
1984年 | 53篇 |
1983年 | 46篇 |
1982年 | 45篇 |
1981年 | 54篇 |
1980年 | 55篇 |
1979年 | 43篇 |
1978年 | 36篇 |
1977年 | 34篇 |
1976年 | 27篇 |
1975年 | 29篇 |
1974年 | 11篇 |
1972年 | 11篇 |
1966年 | 11篇 |
排序方式: 共有2919条查询结果,搜索用时 46 毫秒
991.
992.
DE Wood JH Burridge FM Van Wijck C. McFadden RA Hitchcock AD Pandyan A. Haugh JJ Salazar-Torres ID Swain 《Disability and rehabilitation》2005,27(1):19-33
Purpose: To review and characterise biomechanical approaches for the measurement of spasticity as one component of the upper motor neurone syndrome. Method: Systematic literature searches based on defined constructs and a four-step review process of approaches used or described to measure spasticity, its association with function or associated phenomena. Most approaches were limited to individual joints and therefore, to reflect this trend, references were grouped according to which body joint(s) were investigated or whether it addressed a functional activity. For each joint, references were further sub-divided into the types of measurement method described. Results: A database of 335 references was established for the review process. The knee, ankle and elbow joints were the most popular, perhaps reflecting the assumption that they are mono-planar in movement and therefore simpler to assess. Seven measurement methods were identified: five involving passive movement (manual, controlled displacement, controlled torque, gravitational and tendon tap) and two involving active movement (voluntary and functional). Generally, the equipment described was in an experimental stage and there was a lack of information on system properties, such as accuracy or reliability. Patient testing was either by cohort or case studies. The review also conveyed the myriad of interpretations of the concept of spasticity. Conclusions: Though biomechanical approaches provide quantitative data, the review highlighted several limitations that have prevented them being established as an appropriate method for clinical application to measure spasticity. 相似文献
993.
H. N. Rosen M. Lim J. Garber S. Moreau H. N. Bhargava J. Pallotta R. Spark S. Greenspan M. Rosenblatt M. Chorev 《Calcified tissue international》1997,61(6):455-459
BIM-44002, a pure competitive antagonist of parathyroid hormone (PTH), has a high affinity for the PTH/PTHrP receptor in vitro, and can completely inhibit the actions of a PTH agonist in rats in vivo. Toxicology studies in rats and dogs showed BIM-44002 to be devoid of any adverse effects. Therefore we undertook an investigation
to evaluate the potential utility of BIM-44002 in lowering elevated serum calcium in three patients with primary hyperparathyroidism.
BIM-44002 was administered by continuous intravenous infusion at dosages of 100 μg/hour (370 nmol/hour) for 12 hours, followed
by 200 μg/hour for 12 hours, followed by 400 μg/hour for 12 hours. Vital signs and serum ionized and total calcium were monitored
hourly and for 3 hours after cessation of the infusion. Blood for PTH determinations was obtained at the same time points.
Serum calcium and PTH did not change during and after the infusion of the antagonist. No subject experienced any adverse reactions
to the infusion of the antagonist. We conclude that although the PTH antagonist BIM-44002 was effective both in vitro and in vivo in animals, and it was safe in humans, it was not able to lower serum calcium in patients with hyperparathyroidism. Possible
reasons for lack of clinical efficacy are discussed. 相似文献
994.
Access to maternity care in rural Washington: its effect on neonatal outcomes and resource use. 总被引:6,自引:0,他引:6
下载免费PDF全文
![点击此处可从《American journal of public health》网站下载免费的PDF全文](/ch/ext_images/free.gif)
OBJECTIVES: This study sought to ascertain the effects of poor local access to obstetric care on the risks of having a neonate diagnosed as non-normal, a long hospital stay, and/or high hospital charges. METHODS: Washington State birth certificates linked with hospital discharge abstracts of mothers and neonates were used to study 29809 births to residents of rural areas. Births to women from rural areas where more than two thirds of the women left for care were compared with births to women from rural areas where fewer than one third left for care. RESULTS: Poor local access to providers of obstetric care was associated with a significantly greater risk of having a non-normal neonate for both Medicaid and privately insured patients. However, poor local access to care was consistently associated with higher charges and increased hospital length of stay only if the patient was privately insured. CONCLUSIONS: These results indicate that local maternity services may help prevent non-normal births to rural women and, among privately insured women, might decrease use of neonatal resources. 相似文献
995.
996.
Som PM; Dillon WP; Fullerton GD; Zimmerman RA; Rajagopalan B; Marom Z 《Radiology》1989,172(2):515-520
Clinically assessed chronic proteinacious sinonasal secretions usually have long T1 and T2 relaxation times reflecting their high water content. However, in some cases variable combinations of short and long T1 and T2 relaxation times are found. To study the causes of these findings, the magnetic resonance (MR) images of 41 patients with surgically proved, chronically obstructed sinonasal secretions were studied. The relative signal intensities on both T1- and T2-weighted sequences of the sinus specimens were correlated with the gross viscosity of the specimens at surgery. Ten specimens were collected that were not contaminated with either blood or saline. UV spectrophotometric analysis of four of these samples excluded the presence of methemoglobin. Total protein content was determined in five samples, and in vitro T1 and T2 values were measured in one sample. These T1 and T2 relaxation times were accurately predicted with use of a standard pure lysozyme protein solution with the same concentration as the specimen. In addition, the observed T1- and T2-weighted signal intensities on the 41 MR images were predicted from an analysis of pure protein solutions. This study concludes that the primary causes of the variable T1 and T2 relaxation times of chronic sinonasal secretions are the macromolecular protein concentration, the amount of free water, and the specimen viscosity. Furthermore, an orderly and predictable transition of these signal intensities occurs over time. 相似文献
997.
HTLV-II is a rarely encountered human retrovirus that has been linked to atypical presentations of hairy-cell leukemia, as well as a variety of T-cell malignancies. Recently, HTLV-II prevalence has increased in the United States, particularly in populations of intravenous drug abusers. Comparative study of HTLV-I and HTLV-II has allowed for important insights into the mechanisms of retroviral replication and T-cell transformation. 相似文献
998.
Multiple-unit and second transfusions of red cells enzymatically converted from group B to group O: report on the end of phase 1 trials 总被引:5,自引:0,他引:5
BACKGROUND: It has previously been shown that 1 and 2 units (200 - 400 mL) of red cells (RBCs) enzymatically converted from group B to group O by treatment with alpha-galactosidase (ECO RBCs) are safe and efficacious when transfused to normal group O or A persons. STUDY DESIGN AND METHODS: The current report describes studies in which 1) normal group A and O subjects received large volumes of these cells (3 units), 2) some group O subjects underwent transfusion several months later, and 3) ECO RBCs were prepared by the use of recombinant coffee bean alpha-galactosidase and transfused to a group O subject, to demonstrate the in vivo equivalence of ECO RBCs, whether prepared with native or recombinant alpha-galactosidase. RESULTS: Clinical evaluation (hematologic tests, chemistry analysis, urinalysis) and serologic analyses did not reveal any evidence of subtle or acute transfusion reaction or significant increase in preexisting anti-B titer. ECO RBC survival within the circulation of the recipients was normal (24-hour survival, 95.5 +/− 0.9%; t1/2, 34.7 +/− 6.1 days; n = 8 transfusions), and the efficacy of the transfusions was manifested in elevations in recipient hemoglobin and hematocrit (hemoglobin increase, 1.5 +/− 0.6 g/dL; hematocrit increase, 3.6 +/− 1.6%; n = 8 transfusions). CONCLUSION: ECO RBCs are safe and efficacious when transfused more than once or in multiple-unit volumes to group O or A subjects, and ECO RBCs prepared with recombinant or native enzyme are equivalent in vivo. 相似文献
999.
Two infants presenting with respiratory distress in the first 24 h of life are described. Both patients underwent extensive investigation before the diagnosis of surfactant protein B-deficiency was reached. Both children died within 2 months of birth. Parental consanguinity was known to be a feature in the first case, who proved to have a previously unrecognized mutation of the surfactant protein B gene. In the second case, a history of parental consanguinity was not sought from the Caucasian family, but was later volunteered by the parents themselves. Case 2 proved to have the "common" surfactant protein B-deficient genotype. The key to diagnosis is having a high index of suspicion in any term or near-term newborn with severe respiratory distress; parental consanguinity must be excluded. Surfactant protein B-deficiency can be readily diagnosed from bronchoalveolar lavage specimens; a simple, inexpensive procedure which is well tolerated in newborns. 相似文献
1000.
Two cases are reported in which multiple, well-defined lesions of the liver, as seen on computed tomographic (CT) scans and sonograms, were thought to represent metastatic malignancy. Results from radionuclide scans and biopsies (and surgery in one case) indicated the correct diagnosis was fatty infiltration of the liver. Focal fatty infiltration should be considered in cases of multiple discrete hepatic lesions, especially in patients with a predisposing condition. Radionuclide studies and biopsies may be needed to confirm the diagnosis by CT. 相似文献