全文获取类型
收费全文 | 259篇 |
免费 | 26篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 3篇 |
妇产科学 | 1篇 |
基础医学 | 40篇 |
口腔科学 | 18篇 |
临床医学 | 59篇 |
内科学 | 69篇 |
皮肤病学 | 3篇 |
神经病学 | 4篇 |
特种医学 | 14篇 |
外科学 | 27篇 |
综合类 | 3篇 |
预防医学 | 6篇 |
药学 | 28篇 |
肿瘤学 | 10篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 9篇 |
2012年 | 18篇 |
2011年 | 8篇 |
2010年 | 10篇 |
2009年 | 16篇 |
2008年 | 10篇 |
2007年 | 8篇 |
2006年 | 15篇 |
2005年 | 11篇 |
2004年 | 8篇 |
2003年 | 8篇 |
2002年 | 7篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 16篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1970年 | 1篇 |
1968年 | 3篇 |
排序方式: 共有286条查询结果,搜索用时 15 毫秒
1.
Circannual variation in lymphocyte subsets, revisited 总被引:2,自引:0,他引:2
BACKGROUND: Circadian and circannual variations in lymphocyte subsets, especially CD8+ T-lymphocytes, have been reported. This study focuses on CD4+ T-lymphocyte seasonal variation over a 6-year 8-month period. STUDY DESIGN AND METHODS: Lymphocyte subsets were quantitated monthly for four healthy individuals from 1986 through 1992 as part of a flow cytometry quality-control program. RESULTS: In general, there were no significant seasonal changes in the total number of white cells or in total lymphocyte counts. The absolute numbers of CD4+ T-lymphocytes were lowest in summer when the CD8+ T-lymphocytes were highest. Mean CD4+ T-lymphocyte counts were 846, 967, 618, and 695 per microL for Subjects 1 through 4, respectively, in winter and 432, 670, 355, and 766 per microL, respectively, in summer. Two healthy subjects had CD4+ T-lymphocyte counts lower than 300 per microL on one or more occasions during the study period. In three of the four subjects, the percentage of B-lymphocytes in winter was almost double that in summer. In one of the four subjects, no circannual rhythm was observed in these lymphocyte subpopulations. CONCLUSION: The seasonal variation in CD4+ T- lymphocyte counts demonstrated in three healthy individuals over almost 7 years is again of interest in light of renewed consideration of using surrogate tests, such as CD4+ T-lymphocyte counts, to screen for AIDS- like diseases that may be in the blood supply. 相似文献
2.
The family history in family practice: a questionnaire study 总被引:9,自引:7,他引:2
OBJECTIVES: Our aims were to investigate family medical history taking in
general practice, and to evaluate the value attached to the family medical
history as an aid to decision making in general practice. METHOD: A postal
questionnaire survey was conducted among all 291 GPs working within the
Calderdale and Kirklees Health Authority area. Each questionnaire was
followed by a reminder. The main outcome measures were answers to questions
on routine and opportunistic family history taking and a question about
transmitting knowledge about genetic risk to other members of the family.
Questions were also posed about the value attached to the family medical
history as an aid to decision making. RESULTS: A total of 193 GPs returned
the questionnaire (response rate 66.3%). On registration, 94.3% of GPs
indicated that enquiries were made about a family history of coronary heart
disease. Breast and colorectal cancer were specifically asked about by
48.4% and 30.7% of GPs, respectively. One-fifth of respondents indicated
that they asked a general question about family medical history. A little
over one-quarter of respondents indicated that they made opportunistic
enquiries about the family history or suggested that the patient should
inform other members of the family about possible risks. In the scenarios
highlighted in this study, the majority of respondents felt that the family
medical history had value as an aid to decision making. This was
particularly the case for checking a patient's cholesterol (92.1%) and for
initiating referrals in younger patients with possible cancer-related
symptoms (three-quarters of respondents). CONCLUSION: GPs value the family
medical history as an aid to decision making. Unfortunately, apart from
enquiries about coronary heart disease, routine or opportunistic family
history taking is not occurring in practice. Mechanisms need to be sought
to extract information from the family medical history so that it can be
more effectively used by GPs.
相似文献
3.
Thromboxane A(2) (TXA(2)) is a potent vasoconstrictor and platelet aggregator whose synthesis is increased in a variety of cardiovascular diseases. TXA(2) receptor antagonists have been used to (a) establish a pathophysiologic role for TXA(2) in a variety of cardiovascular diseases, (b) subtype platelet and vascular receptors, (c) elucidate structural characteristics of the receptor, and (d) aid in its purification. However, much still remains to be learned about the structure and function of TXA(2) receptors. 相似文献
4.
5.
Emily E. Brown Yi Zhen Joan Lee Marc K. Halushka Charles Steenbergen Nicole M. Johnson Johana Almansa 《Amyloid》2017,24(2):92-95
Amyloidosis is a group of conditions characterized by the accumulation of amyloid deposits in various tissues. Among these disorders, ATTR amyloidosis occurs either with or without a TTR pathogenic variant. Treatment for amyloidosis depends on the subtype, which is often identified through a tissue biopsy followed by liquid chromatography tandem mass spectrometry (LC–MS/MS). Genetic testing may be done to confirm these results for patients with ATTR amyloidosis; however, the necessity of genetic testing after LC–MS/MS has not been evaluated. A retrospective review identified 153 patients diagnosed with biopsy-proven ATTR amyloidosis, and 56 of these patients underwent both genetic testing and LC–MS/MS. LC–MS/MS and proteomics correctly reported the mutant peptide and heterozygosity in 47/56 (84%) cases. It failed to identify two individuals who were homozygous for the ATTRV122I mutation and failed to detect the following mutations in six other individuals: ATTRA19D, ATTRF44L, ATTRT60A, ATTRI68L and ATTRV122I. Therefore, LC–MS/MS is not sufficient to rule out a pathogenic mutation in cases of ATTR amyloid, and genetic testing should be performed in most cases of ATTR amyloidosis. Correct recognition of hereditary ATTR amyloidosis is important for estimating prognosis, proper familial counselling and guiding use of therapies, such as liver transplantation. 相似文献
6.
Mechanism of platelet inhibition by nitric oxide: In vivo phosphorylation of thromboxane receptor by cyclic GMP-dependent protein kinase 总被引:7,自引:0,他引:7 下载免费PDF全文
Guang-Rong Wang Yan Zhu Perry V. Halushka Thomas M. Lincoln Michael E. Mendelsohn 《Proceedings of the National Academy of Sciences of the United States of America》1998,95(9):4888-4893
Nitric oxide (NO) is a potent vasodilator and inhibitor of platelet activation. NO stimulates production of cGMP and activates cGMP-dependent protein kinase (G kinase), which by an unknown mechanism leads to inhibition of Gαq-phospholipase C-inositol 1,4,5-triphosphate signaling and intracellular calcium mobilization for several important agonists, including thromboxane A2 (TXA2). To explore the mechanism of platelet inhibition by NO, activation of platelet TXA2 receptors in the presence of cGMP was studied. The nonhydrolyzable analog 8-bromo-cyclic GMP (8-Br-cGMP) potently inhibited activation of the TXA2-specific GTPase in platelet membranes in a concentration-dependent fashion, suggesting that G kinase catalyzes the phosphorylation of some proximal component of the receptor–G protein signaling pathway. Nanomolar concentrations of G kinase were found to catalyze the phosphorylation of platelet TXA2 receptors in vitro, but not Gαq copurifying with the TXA2 receptors in these experiments. Using immunoaffinity methods, in vivo phosphorylation of TXA2 receptors by cyclic GMP was demonstrated from 32P-labeled cells treated with 8-Br-cGMP. Peptide mapping studies of in vivo phosphorylated TXA2 receptors demonstrated cGMP mediates phosphorylation of the carboxyl terminus of the TXA2 receptor. G kinase also catalyzed the phosphorylation of peptides corresponding to the cytoplasmic tails of both α and β forms of the receptor but not control peptide or a peptide corresponding to the third intracytoplasmic loop of the TXA2 receptor. These data identify TXA2 receptors as cGMP-dependent protein kinase substrates and support a novel mechanism for the inhibition of cell function by NO in which activation of G kinase inhibits signaling by G protein-coupled receptors by catalyzing their phosphorylation. 相似文献
7.
8.
9.
10.