全文获取类型
收费全文 | 20307篇 |
免费 | 1577篇 |
国内免费 | 650篇 |
专业分类
耳鼻咽喉 | 173篇 |
儿科学 | 348篇 |
妇产科学 | 562篇 |
基础医学 | 2619篇 |
口腔科学 | 420篇 |
临床医学 | 2283篇 |
内科学 | 4244篇 |
皮肤病学 | 256篇 |
神经病学 | 1198篇 |
特种医学 | 753篇 |
外国民族医学 | 3篇 |
外科学 | 2663篇 |
综合类 | 1505篇 |
现状与发展 | 3篇 |
一般理论 | 5篇 |
预防医学 | 1099篇 |
眼科学 | 746篇 |
药学 | 1662篇 |
6篇 | |
中国医学 | 572篇 |
肿瘤学 | 1414篇 |
出版年
2024年 | 35篇 |
2023年 | 230篇 |
2022年 | 460篇 |
2021年 | 696篇 |
2020年 | 454篇 |
2019年 | 493篇 |
2018年 | 574篇 |
2017年 | 509篇 |
2016年 | 500篇 |
2015年 | 673篇 |
2014年 | 814篇 |
2013年 | 939篇 |
2012年 | 1400篇 |
2011年 | 1494篇 |
2010年 | 905篇 |
2009年 | 750篇 |
2008年 | 1101篇 |
2007年 | 1154篇 |
2006年 | 1144篇 |
2005年 | 1133篇 |
2004年 | 925篇 |
2003年 | 798篇 |
2002年 | 780篇 |
2001年 | 553篇 |
2000年 | 542篇 |
1999年 | 500篇 |
1998年 | 253篇 |
1997年 | 264篇 |
1996年 | 209篇 |
1995年 | 175篇 |
1994年 | 146篇 |
1993年 | 111篇 |
1992年 | 222篇 |
1991年 | 205篇 |
1990年 | 178篇 |
1989年 | 180篇 |
1988年 | 150篇 |
1987年 | 135篇 |
1986年 | 117篇 |
1985年 | 105篇 |
1984年 | 61篇 |
1983年 | 43篇 |
1982年 | 70篇 |
1981年 | 53篇 |
1980年 | 59篇 |
1979年 | 40篇 |
1978年 | 36篇 |
1977年 | 33篇 |
1976年 | 25篇 |
1975年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
The use of item banks and computerized adaptive testing (CAT) begins with clear definitions of important outcomes, and references those definitions to specific questions gathered into large and well-studied pools, or “banks” of items. Items can be selected from the bank to form customized short scales, or can be administered in a sequence and length determined by a computer programmed for precision and clinical relevance. Although far from perfect, such item banks can form a common definition and understanding of human symptoms and functional problems such as fatigue, pain, depression, mobility, social function, sensory function, and many other health concepts that we can only measure by asking people directly. The support of the National Institutes of Health (NIH), as witnessed by its cooperative agreement with measurement experts through the NIH Roadmap Initiative known as PROMIS (www.nihpromis.org), is a big step in that direction. Our approach to item banking and CAT is practical; as focused on application as it is on science or theory. From a practical perspective, we frequently must decide whether to re-write and retest an item, add more items to fill gaps (often at the ceiling of the measure), re-test a bank after some modifications, or split up a bank into units that are more unidimensional, yet less clinically relevant or complete. These decisions are not easy, and yet they are rarely unforgiving. We encourage people to build practical tools that are capable of producing multiple short form measures and CAT administrations from common banks, and to further our understanding of these banks with various clinical populations and ages, so that with time the scores that emerge from these many activities begin to have not only a common metric and range, but a shared meaning and understanding across users. In this paper, we provide an overview of item banking and CAT, discuss our approach to item banking and its byproducts, describe testing options, discuss an example of CAT for fatigue, and discuss models for long term sustainability of an entity such as PROMIS. Some barriers to success include limitations in the methods themselves, controversies and disagreements across approaches, and end-user reluctance to move away from the familiar. 相似文献
22.
Interleukin-5 has a specific role in various eosinophilic activities. It is the predominant cytokine produces by activated T-lymphocytes isolated from patients with idiopathic hypereosinophilic syndrome. We studied a young patient suffering from idiopathic hypereosinophilic syndrome who presented with Horner's syndrome, peripheral neuropathy and skin ulcers. The IL-5 gene expression by CD4+ T-lymphocytes and the peripheral eosinophil count were raised. The skin ulcers continued to deteriorate despite a swift reduction of the IL-5 gene expression and peripheral eosinophil count following systemic corticosteroid treatment. We suggest that peripheral eosinophilia may not be responsible for the damage in skin lesions and more aggressive treatment may be required. 相似文献
23.
Marina Quartu Maria Pina Serra Annalisa Manca Paolo Follesa Maria Letizia Lai Marina Del Fiacco 《International journal of developmental neuroscience》2003,21(1):23-33
The immunohistochemical occurrence of the neurotrophin (NT) proteins nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-4 (NT-4), and neurotrophin-3 (NT-3) is shown in the pre-term newborn, infant, and adult human post-mortem cerebellum. The NT-like immunoreactive structures were unevenly distributed and showed regional differences among cerebellar lobules and folia. NGF-, NT-4-, and NT-3-positive neuronal perikarya were observed in all specimens examined. At variance with the other neurotrophins, the BDNF antiserum labelled neuronal cell bodies only in newborn life and infancy, as well as extensive nerve fibre systems, whose density increased with age. The NT-antibodies, tested by Western blot on human cerebellum homogenates, revealed immunoreactive bands corresponding to proteins of heterogenous molecular weight. The results obtained provide a first demonstration of the tissue localization of the NTs in the human cerebellum from perinatal to adult age, thus suggesting their involvement in the development, differentiation and maintenance of the cerebellar connectivity. Codistribution of the four NTs or sets of them was observed in cortical and deep nuclei neurons. Multiple trophic roles for NTs, encompassing the classic target-derived and local mechanisms of support, are envisaged as significant in development, differentiation, and maintenance of the human cerebellar connectivity. 相似文献
24.
25.
Reports of the incidence of postoperative deep vein thrombosis in the Chinese population of Taiwan are few in the literature. Over a 3 year period, the fibrinogen degradation products test, the pulse volume recorder, and venography were used to study 220 patients undergoing major operations at the Veterans General Hospital in Taipei, Taiwan. Deep vein thrombosis was found in 17 patients (7.7 percent). A comparison of the three diagnostic methods showed that the sensitivities of the fibrinogen degradation products test and the pulse volume recorder were 56.3 percent and 93.7 percent, respectively; the specificities, 97.4 percent and 95.7 percent, respectively; and the accuracies, 85.5 percent and 95.5 percent, respectively. These results support the combined use of the fibrinogen degradation products test and the pulse volume recorder for screening and diagnosing deep vein thrombosis. 相似文献
26.
Human trophoblast and choriocarcinoma expression of the growth
factor pleiotrophin attributable to germ-line insertion of
an endogenous retrovirus 下载免费PDF全文
27.
Guerriero S Ajossa S Lai MP Risalvato A Paoletti AM Melis GB 《Human reproduction update》1999,5(5):515-529
This review describes the usefulness of colour Doppler energy (CDE) (or power Doppler) imaging to measure vascularization in the female reproductive tract. CDE imaging is characterized by an increased sensitivity to flow, and thus may be useful in low-flow states and when optimal Doppler angles cannot be obtained. In addition, longer segments of vessels and more individual vessels can be visualized with CDE imaging. The role of CDE imaging in the evaluation of stromal vasculature in normal and in polycystic ovaries is described, and the relationship between follicular vascularity and outcome following in-vitro fertilization are discussed, together with the findings obtained from the evaluation of thecal arteriole of corpus luteum in early pregnancy. The fundamental role of CDE imaging in differentiation among ovarian masses is also reviewed. We summarize the role of CDE imaging in pregnancy, and describe two new applications of three-dimensional power Doppler sonography and the use of ultrasound contrast media. In conclusion, CDE imaging can replace conventional colour Doppler when the information on the direction of flow is not useful. Moreover, the technique appears superior to others for describing microvascular architecture and determining the presence or absence of flow. 相似文献
28.
Lai J Gouldstone A Butler JP Federspiel WJ Loring SH 《Respiratory physiology & neurobiology》2002,131(3):233-243
The pleural space is modeled in two dimensions as a thin layer of fluid separating a deformable membrane and a rigid surface containing a bump. We computed the steady-state membrane configuration and fluid pressure distribution during relative sliding of the two surfaces. For physiologically relevant values of membrane tension, shear flow-induced pressures near the bump and far-field pressure gradients are similar to those measured in vivo within the pleural space (e.g. Lai-Fook et al.) [J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 56 (1984) 1633-1639]. Deformation of the membrane over the bump suggests that the pressure field generated by the sliding motion promotes an even layer of fluid in the pleural space, preventing asperities from touching. Results also suggest a possible mechanism for pleural fluid redistribution during breathing, whereby irreversible fluid motion is associated with the deformability of the membrane. 相似文献
29.
由中、德科学中心发起、浙江大学与德国柏林洪堡大学共同主办的中德外科及基础病理新进展研讨会于2004年4月20日~22日在浙江省杭州市举行。会议由浙江大学来茂德教授和德国Humboldt大学Dietel教授主持,中、德两国共23名病理学专家参加了此次高水准国际病理学会议。会议主要涉及WHO肿瘤新分类、第6版国际抗癌联盟(UICC)TNM分期以及SARS病研究等。会议促进了双方病理学界的交流,增进了友谊,为今后中、德两国病理学界的进一步交流、合作开创了新局面。 相似文献
30.
Role of bacterial products in periodontitis: immune response in gnotobiotic rats monoinfected with Eikenella corrodens. 下载免费PDF全文
D A Johnson U H Behling C H Lai M Listgarten S Socransky A Nowotny 《Infection and immunity》1978,19(1):246-253
The development of humoral and cell-mediated immune responses to Eikenella corrodens (a bacterium that causes periodontal lesions in gnotobiotic rats) was measured and compared with the rate of appearance of macroscopic lesions. A possible inverse relationship was found. A strong cell-mediated immune response, as measured by skin reactivity and lymphocyte mitogenesis, occurred between 4 and 6 weeks after infection and subsided soon thereafter to a low response level. Humoral antibodies to endotoxin from E. corrodens could not be detected at any time. The disease developed only after the cell-mediated immune response diminished, thus suggesting that lack of an efficient immune response may permit the development of the disease. This is seemingly in contradiction to the assumption that tissue destruction in such cases is caused by the immune response and its products. We are inclined to believe, based on our findings reported here, that the lack of immune responsiveness to the bacterium and/or its products is the major causative factor in the development of periodontitis. At the same time, we wish to emphasize that occurrence of both phenomena during the long development of periodontal disease is possible. 相似文献