全文获取类型
收费全文 | 2163篇 |
免费 | 212篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 101篇 |
妇产科学 | 55篇 |
基础医学 | 326篇 |
口腔科学 | 30篇 |
临床医学 | 410篇 |
内科学 | 477篇 |
皮肤病学 | 54篇 |
神经病学 | 103篇 |
特种医学 | 140篇 |
外科学 | 227篇 |
综合类 | 52篇 |
一般理论 | 1篇 |
预防医学 | 170篇 |
眼科学 | 40篇 |
药学 | 69篇 |
肿瘤学 | 120篇 |
出版年
2023年 | 26篇 |
2022年 | 11篇 |
2021年 | 26篇 |
2020年 | 39篇 |
2019年 | 44篇 |
2018年 | 50篇 |
2017年 | 44篇 |
2016年 | 63篇 |
2015年 | 50篇 |
2014年 | 78篇 |
2013年 | 92篇 |
2012年 | 77篇 |
2011年 | 91篇 |
2010年 | 61篇 |
2009年 | 90篇 |
2008年 | 84篇 |
2007年 | 80篇 |
2006年 | 112篇 |
2005年 | 87篇 |
2004年 | 81篇 |
2003年 | 81篇 |
2002年 | 56篇 |
2001年 | 85篇 |
2000年 | 72篇 |
1999年 | 65篇 |
1998年 | 59篇 |
1997年 | 57篇 |
1996年 | 53篇 |
1995年 | 50篇 |
1994年 | 34篇 |
1993年 | 43篇 |
1992年 | 43篇 |
1991年 | 32篇 |
1990年 | 30篇 |
1989年 | 34篇 |
1988年 | 27篇 |
1987年 | 33篇 |
1986年 | 30篇 |
1985年 | 20篇 |
1984年 | 23篇 |
1983年 | 18篇 |
1982年 | 16篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 19篇 |
1978年 | 13篇 |
1977年 | 15篇 |
1976年 | 9篇 |
1975年 | 7篇 |
1973年 | 9篇 |
排序方式: 共有2388条查询结果,搜索用时 15 毫秒
1.
Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography 总被引:2,自引:0,他引:2
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study. 相似文献
2.
Shigeru Ichioka MD ; Naomi Sekiya MT ; Masahiro Shibata PhD ; Takashi Nakatsuka MD 《Wound repair and regeneration》2007,15(4):572-576
The leukocyte-endothelium interaction is known to contribute to reperfusion injury, which is considered to participate in the pathophysiology of pressure ulcers, and integrin alphaV beta3 (alphavbeta3) has been shown to mediate the processes of cellular adhesion in various types of cells. This study aims to clarify leukocyte behavior in our original microcirculatory pressure-induced reperfusion model, which can visualize the microcirculation in vivo. We also estimated the effect of alphavbeta3 integrin inhibition on the reduction of the leukocyte-endothelium interaction. Mice with dorsal skinfold chambers were divided into three groups: the baseline group (n=6), in which animals received no compression; the compression-reperfusion group (n=6), in which animals underwent 2-hour compression of the dorsal skin, followed by release, and the inhibitor-treated group (n=7), in which an alphavbeta3 inhibitor, CP4715, was administered in addition to the compression-release procedure. Staining with rhodamine 6G quantitatively visualized leukocyte behavior under the intravital fluorescent microscope. Compression-reperfusion induced a significant increase in rolling, sticking, and extravasation of the leukocytes. Treatment with the inhibitor strikingly reduced leukocyte sticking and extravasation. The present experiment has provided evidence that alphavbeta3 inhibition reduces leukocyte-endothelium interaction in our original pressure-induced reperfusion model. 相似文献
3.
Gina Kearney MSN RN CS AHN-BC JeMe Cioppa-Mosca PT MBA Margaret G. E. Peterson Ph.D C. Ronald MacKenzie MD 《HSS journal》2007,3(2):198-201
In an outpatient rehabilitation setting, both patients’ use and therapists’ knowledge of complementary and alternative medicine
(CAM) varies widely. Based on this observation and a recognition of CAM as an emerging practice area for rehabilitation professionals,
it was felt that a thorough and consistent approach to the education and orientation of physical therapists to the world of
CAM and integrative care was needed. This special interest paper will describe one center’s approach, development, and use
of a unique and comprehensive training manual designed to provide both a structured and standardized approach for educating
physical therapists about CAM and related therapeutic modalities. This innovative teaching tool allows for multiple methods
of content delivery within a multidisciplinary format and can be used for those who practice currently or desire to practice
in an integrative care environment. 相似文献
4.
Dr. S. Eggstein MD G. Manthey MT T. Hirsch PhD F. Baas MA B. U. V. Specht MD E. H. Farthmann MD 《Digestive diseases and sciences》1996,41(6):1069-1075
Epidermal growth factor receptors (EGFR) andras mutations are known to play a significant role in controlling cell growth and tumor promotion. Both of them transmit mitogenic signals to the nucleus by activation of Raf-1 kinase. In this study, the expression of EGFR and mutant Ras proteins, and, for the first time, the expression, phosphorylation and kinase activity of Raf-1 kinase have been determined in paired samples of colorectal cancer and mucosa. The tumor and mucosa samples did not differ significantly with regard to Raf-1 kinase content and activity. A major difference between tumors and mucosa was found, however, in the phosphorylation of Raf-1. Most of the mucosa samples (13/20), but only 1/20 of the cancer samples, contained hyperphosphorylated Raf-1. EGFR were significantly (p=0.0025) decreased in the tumors. The decreased phosphorylation of Raf-1 in colonic carcinomas could be the result of activation of Raf-1 phosphatases or inactivation of kinases phosphorylating Raf-1. New forms of treatment based on EGFR overexpression do not seem to be suitable for the majority of colonic cancers.This work was supported by the state of Baden-Württemberg (Verbundforschungsprojekt: Aufklärung von Mechanismen der Tumorentstehung und Tumorabwehr). 相似文献
5.
Analysis of ischemia-reperfusion injury in a microcirculatory model of pressure ulcers 总被引:2,自引:0,他引:2
Shinsaku Tsuji MD ; Shigeru Ichioka MD ; Naomi Sekiya MT ; Takashi Nakatsuka MD 《Wound repair and regeneration》2005,13(2):209-215
The aim of this study was to establish a pressure ulcer model that visualizes the microcirculation, and to examine the participation of ischemia-reperfusion injury in the pathophysiology of pressure ulcers. An original system composed of a new skin fold chamber and compression device allowed loading quantitative vertical stress to the skin. An intravital microscopic technique enabled direct visualization of the microcirculation in the physiological condition and in response to pressure application. To estimate the effect of ischemia-reperfusion injury, animals were divided into two groups: the compression-release group (n = 8), in which the animals received four cycles of compression-release which consisted of 2 hours of compression followed by 1 hour of pressure release; and the compression alone group (n = 8) in which the animals underwent continuous compression for 8 hours. Functional capillary density was quantified before the compression procedure and on day 1 (35 hours) after the first evaluation. The cyclic compression-release procedure significantly decreased functional capillary density as compared to continuous compression, indicating that in our experimental setting repetition of ischemia-reperfusion cycle more severely damaged the microcirculation than single prolonged ischemic insult. This finding supports the significant contribution of ischemia-reperfusion injury to the pathophysiology of pressure ulcers at the level of dynamic in vivo microcirculation. 相似文献
6.
One of the few disinfectants known to inactivate the causative agent of Creutzfeldt-Jakob Disease is NaOH. In this study, NaOH was evaluated as a possible routine treatment for human dura mater alloimplants. Use of high concentration NaOH (1 M) resulted in protein loss and macroscopic changes to the tissue. Lower concentrations (0.1 M), although exhibiting little direct detrimental effect, greatly increased the susceptibility of the tissue to collagenase digestion. The use of NaOH treated commercial or institutionally prepared human dura mater should be approached with caution. 相似文献
7.
Source agreement in assessing youth stress and negative affectivity: New evidence for an old problem
The present study examined dichotomies potentially relevant to parentchild and interparent agreement in the assessment of internalizing problems in youngsters. Specifically, 98 children and their parents completed the Daily Life Stressors Scale or a variant to examine child ratings of daily stress, parent ratings of their children's daily stress, and parent predictions of how their children would self-rate their stress. In addition, a distinction was made between subscores of negative affectivity and stressful life events. Results indicated moderate parent-child and interparent agreement, with the latter somewhat more influenced by a negative affectivity-stressful events dichotomy. Parent-child agreement appeared more enhanced for items involving more parental contact. Implications of these data for future research are discussed. 相似文献
8.
IgM allotype heterozygous F1 mice were independently suppressed for Igh6a or Igh6b to
evaluate the contribution of B-1 and B-2 cells to natural serum IgM levels and Ab responses.
B-2 B cells expressing IgM of the suppressed allotype were evident in the spleens of
suppressed mice 4 to 6 weeks after cessation of the suppression regimen, whereas B-1 B
cells of the suppressed allotype were undetectable for up to 9 months. Although serum IgM
of the suppressed allotype was initially depleted in mice suppressed for either allotype, by
7 months of age, there were detectable levels of IgM of the suppressed allotype in the
serum; however, the levels were significantly below that found in nonsuppressed mice.
When mice were immunized with either the T-independent or T-dependent form of
phosphorylcholine, those suppressed for either allotype, and consequently depleted of B-1
B cells of that allotype, did not respond with phosphorylcholine-specific IgM of the
suppressed allotype. In contrast, when mice were immunized with α1-3 dextran, the Igh6a
allotype-suppressed mice were able to produce dextran-specific IgM of that allotype. These
results show that allotype-bearing B-1 cells of both allotypes can be effectively suppressed
by this suppression protocol and this produces long-lasting effects on B-1 cell levels and
serum IgM of the suppressed allotype. These observations reflect the derivation of the
majority of B-1 cells from fetal-neonatal precursors, which cannot be replaced by newly
emerging B-2 cells of adult origin. Their ablation by antibody treatment results in
permanent alterations to the adult B-cell repertoire. 相似文献
9.
S F Johnson S B Johnson W E Strodel D E Barker P A Kearney 《The Journal of trauma》1991,31(11):1546-1550
Proximal upper extremity (subclavian and axillary) vascular injury (SAVI) and brachial plexus injury (BPI) occur uncommonly. However, BPI may be associated with SAVI and frequently is an important determinant of long-term disability. The medical records of patients with traumatic SAVI, BPI, or both over a 5-year period were reviewed. A total of 31 patients were identified. The group was predominantly male (28 men/3 women) with a mean age of 30.5 +/- 1.8 years (range, 15-63 years). Blunt trauma accounted for 43.5% of SAVI cases and 77.8% of BPI cases. Thirteen patients (41.9%) sustained SAVI alone (group I), 10 patients (32.2%) had combined SAVI and BPI (group II), and 8 patients (25.9%) had BPI alone (group III). Subclavian and axilliary vascular injury occurred in 10 of 18 patients (55.6%) with a BPI. Brachial plexus injury occurred in 10 of 23 patients (43.5%) with a SAVI. Patients with SAVI from blunt trauma were significantly more likely to have an associated complete BPI than patients with penetrating trauma. All patients with a complete BPI (6 patients) had an associated SAVI regardless of mechanism of injury. Only one patient with a partial BPI from blunt trauma had an associated SAVI. The Injury Severity Score was significantly higher for patients in group II. An average of 2.8 and 3.3 associated injuries were observed in patients with SAVI (groups I and II) versus patients without SAVI (group III), respectively. No patient who had a complete BPI showed an improvement in neurologic status during a mean follow-up of 7.2 months. No late vascular sequelae occurred in group-III patients.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
10.
Our previous study of natural autoantibodies showed that anti-lymphocyte antibodies are frequently produced by perinatal B cells from normal strains of mice. One-third of these monoclonal antibodies (mAb) recognized similar epitopes on the surface of thymocytes. In the present report, we have characterized the molecule recognized by three of these mAb (D10, G7, 22). These mAb identified a 100-kDa protein (p100) on the surface of thymocytes. This protein resolved into 70-kDa polypeptide chains under reducing conditions. Inhibition experiments as well as antibody immunoprecipitations in the presence of mild detergents revealed non-covalent association of the p100 with Thy-1 and ThB. A similar multimolecular complex was identified following chemical cross-linking of thymocyte surface proteins. Analysis of several Thy-1-defective mutant cells lines, and thymocytes treated with phosphatidylinositol-specific phospholipase C (PI-PLC) showed that the expression of p100 was strongly influenced by Thy-1 molecule. The p100 was resistant to PI-PLC treatment and was not released into the supernatant as was the case for Thy-1 and ThB molecules. These data lead us to propose that the p100 is a transmembrane protein, the expression of which in the plasma membrane is dependent on the association or presence of Thy-1 molecule. 相似文献