全文获取类型
收费全文 | 14743篇 |
免费 | 1259篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 140篇 |
儿科学 | 464篇 |
妇产科学 | 367篇 |
基础医学 | 2162篇 |
口腔科学 | 214篇 |
临床医学 | 1820篇 |
内科学 | 2781篇 |
皮肤病学 | 193篇 |
神经病学 | 1222篇 |
特种医学 | 590篇 |
外科学 | 2304篇 |
综合类 | 267篇 |
一般理论 | 11篇 |
预防医学 | 1350篇 |
眼科学 | 303篇 |
药学 | 994篇 |
中国医学 | 13篇 |
肿瘤学 | 846篇 |
出版年
2022年 | 86篇 |
2021年 | 191篇 |
2020年 | 119篇 |
2019年 | 212篇 |
2018年 | 275篇 |
2017年 | 211篇 |
2016年 | 223篇 |
2015年 | 243篇 |
2014年 | 380篇 |
2013年 | 545篇 |
2012年 | 786篇 |
2011年 | 755篇 |
2010年 | 487篇 |
2009年 | 388篇 |
2008年 | 773篇 |
2007年 | 913篇 |
2006年 | 794篇 |
2005年 | 840篇 |
2004年 | 741篇 |
2003年 | 716篇 |
2002年 | 634篇 |
2001年 | 343篇 |
2000年 | 326篇 |
1999年 | 293篇 |
1998年 | 179篇 |
1997年 | 140篇 |
1996年 | 160篇 |
1995年 | 127篇 |
1994年 | 146篇 |
1993年 | 106篇 |
1992年 | 271篇 |
1991年 | 264篇 |
1990年 | 248篇 |
1989年 | 224篇 |
1988年 | 208篇 |
1987年 | 204篇 |
1986年 | 206篇 |
1985年 | 203篇 |
1984年 | 127篇 |
1983年 | 144篇 |
1982年 | 108篇 |
1981年 | 105篇 |
1980年 | 106篇 |
1979年 | 133篇 |
1978年 | 96篇 |
1977年 | 90篇 |
1976年 | 107篇 |
1975年 | 98篇 |
1974年 | 100篇 |
1973年 | 108篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Most clinicians agree that psychological factors are important considerations in the evaluation and treatment of headache patients. There has been a lack of systematic research, however, that has examined the relationship between these variables. Attention to such factors may become a greater concern as the frequency of a patient's headaches increases, there is increased disability secondary to headaches, and/or there is an inadequate response to usually effective treatment. In addition, there is no consensus as to the proper method to assess psychopathology in headache patients. 相似文献
62.
Ataxia-telangiectasia (A-T) is characterized by impaired recognition and repair of DNA damage and increased sensitivity to ionizing radiation (IR), cancer, and neurodegeneration. We previously showed pregnant knockout mice lacking the A-T gene product ataxia-telangiectasia mutated (Atm) are highly susceptible to the embryopathic effects of IR, which damages DNA, possibly via generation of reactive oxygen species (ROS). Here we show that Atm more broadly protects against both spontaneous and phenytoin-enhanced embryopathies. In the absence of drug exposure, cultured embryos from pregnant Atm knockout mice showed more embryopathies than wild-type littermates, with a gene dose-dependent decrease in susceptibility from -/- to +/- to +/+ embryos (p < 0.05). A similar but significantly enhanced gene dose-dependent pattern of embryopathic susceptibility was evident in Atm knockout embryos exposed to the ROS-initiating teratogen phenytoin (p < 0.05). These results provide the first evidence that Atm has a broad developmental importance beyond IR embryopathies, possibly by protecting the embryo from constitutive and xenobiotic-enhanced oxidative stress, with even heterozygotes showing increased risk. This developmental role of Atm further implicates DNA damage in ROS-mediated teratogenesis and DNA damage response and repair as risk factors for individual susceptibility. 相似文献
63.
64.
J S Wells J O'Sullivan C Aklonis H A Ax A A Tymiak D R Kirsch W H Trejo P Principe 《The Journal of antibiotics》1992,45(12):1892-1898
A screen for antibiotics with activity against tetracycline-resistant microorganisms has led to the isolation of Dactylosporangium sp. (ATCC 53693), a producer of several novel tetracycline derivatives. The major fermentation products, dactylocyclines A and B, were purified and MIC values determined against tetracycline-resistant and tetracycline-sensitive Gram-positive bacteria. The dactylocyclines represent the first naturally occurring tetracycline C2 amides which lack cross resistance with tetracycline. 相似文献
65.
High resolution computed tomography as a predictor of lung histology in systemic sclerosis 总被引:2,自引:0,他引:2 下载免费PDF全文
A U Wells D M Hansell B Corrin N K Harrison P Goldstraw C M Black R M du Bois 《Thorax》1992,47(7):508-512
Background The relative proportions of fibrosis and inflammation seen by open lung biopsy examination is a predictor of disease outcome in fibrosing alveolitis. This study was designed to assess the ability of high resolution computed tomography to predict the histological appearance of open lung biopsy specimens from patients with systemic sclerosis. 相似文献
66.
67.
68.
David M. Dickinson Dawn M. Dykstra Gregory N. Levine Shiqian Li James C. Welch Randall L. Webb 《American journal of transplantation》2005,5(4P2):850-861
The process of collecting and analyzing transplant data is complex. Familiarity with how these data are collected is crucial to a thorough understanding of the information. This article focuses on available OPTN-SRTR data and the continuing evolution of data collection mechanisms; how that data collection system is improving the data quality and reducing the data collection burden; how additional ascertainment of outcomes both completes and validates existing data; and caveats that remain for researchers. This year's article focuses further on research considerations related to cohort choice, timing of data submission, and potential biases in follow-up data. Ongoing improvements in data collection timeliness and scope are covered. The impact of extra ascertainment of outcomes, particularly for post-transplant kidney graft failure from Medicare data, are also examined. A section on graft failure reporting among different sources traces the steps by which the SRTR reconciles different data sources in its analyses. It is important that those reading and conducting transplant research understand the origin, structure, and scope of the available data. All of these issues should be carefully considered when choosing cohorts and data sources for analysis. 相似文献
69.
70.
Keloid fibroblast responsiveness to epidermal growth factor and activation of downstream intracellular signaling pathways. 总被引:8,自引:0,他引:8
Latha Satish Mary Babu Kien T Tran Patricia A Hebda Alan Wells 《Wound repair and regeneration》2004,12(2):183-192
Keloids, which overgrow the boundaries of the original injury, represent aberrations in the fundamental process of wound healing that include over-abundant cell in-migration, cell proliferation, and inflammation, as well as increased extracellular matrix synthesis and defective remodeling. To understand the key events that result in the formation of these abnormal scars would open new avenues for better understanding of excessive repair, and might provide new therapeutic options. We examined epidermal growth factor receptor (EGFR)-induced cell motility in keloid fibroblasts, as this receptor initiates cell migration during normal wound repair. We show that keloid fibroblasts respond to EGF-induced cell migration but the response is somewhat diminished compared to normal adult fibroblasts (approximately 30% reduced); the mitogenic response was similarly blunted (approximately 5% reduced). Keloid fibroblasts express near normal levels of EGFR (82%), but show a much more attenuated activation of EGFR itself and the motility-associated phospholipase C-gamma. This was reflected in part by rapid loss of EGFR upon exposure to EGF. Interestingly, while extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK-MAPK) activation was relatively robust in keloid fibroblasts, the downstream triggering of the motility-associated calpain activity was blunted. This was reflected by high cell-substratum adhesiveness in the keloid fibroblasts. Thus, the blunted migratory response to EGF noted in keloid fibroblasts appears due to limited activation of two important biochemical switches for cell motility. 相似文献