全文获取类型
收费全文 | 23157篇 |
免费 | 1642篇 |
国内免费 | 274篇 |
专业分类
耳鼻咽喉 | 560篇 |
儿科学 | 293篇 |
妇产科学 | 293篇 |
基础医学 | 4006篇 |
口腔科学 | 388篇 |
临床医学 | 1878篇 |
内科学 | 4520篇 |
皮肤病学 | 907篇 |
神经病学 | 1575篇 |
特种医学 | 1638篇 |
外科学 | 2767篇 |
综合类 | 77篇 |
一般理论 | 1篇 |
预防医学 | 798篇 |
眼科学 | 586篇 |
药学 | 2376篇 |
中国医学 | 348篇 |
肿瘤学 | 2062篇 |
出版年
2024年 | 20篇 |
2023年 | 184篇 |
2022年 | 606篇 |
2021年 | 890篇 |
2020年 | 452篇 |
2019年 | 657篇 |
2018年 | 789篇 |
2017年 | 642篇 |
2016年 | 1019篇 |
2015年 | 1387篇 |
2014年 | 1619篇 |
2013年 | 1731篇 |
2012年 | 2446篇 |
2011年 | 2195篇 |
2010年 | 1487篇 |
2009年 | 1146篇 |
2008年 | 1479篇 |
2007年 | 1320篇 |
2006年 | 1063篇 |
2005年 | 1000篇 |
2004年 | 766篇 |
2003年 | 625篇 |
2002年 | 534篇 |
2001年 | 178篇 |
2000年 | 131篇 |
1999年 | 90篇 |
1998年 | 78篇 |
1997年 | 78篇 |
1996年 | 58篇 |
1995年 | 41篇 |
1994年 | 43篇 |
1993年 | 37篇 |
1992年 | 37篇 |
1991年 | 40篇 |
1990年 | 19篇 |
1989年 | 23篇 |
1988年 | 23篇 |
1987年 | 18篇 |
1986年 | 18篇 |
1985年 | 20篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 4篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1973年 | 6篇 |
1971年 | 7篇 |
1967年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Yu Ri An Jeong Han Seung Jun Kim Moon-Ju Oh Jung-Hwa Oh Seok-Joo Yoon Seung Yong Hwang 《Toxicology and Environmental Health Sciences》2010,2(4):245-250
It is important to acknowledge the harmful effects of environmental chemicals in human’s lives. The toxic effects of Diethylstilbestrol (DES), one of the endocrine-disrupting chemicals (EDCs), have been documented in many studies. As expected, DES affect male gendal hormone as well as female’s; therefore, epigenetic study should be considered. In this study, microarray technology was used to study harmful effects on the level of genomics, and here, two types of microarray chips- the Agilent mouse genome 4 × 44 K array for gene expression profiling and the Agilent mouse miRNA v13 for miRNA expression profiling-was used to study the relation between gene and miRNA expression profiles. As a result, we identified 4 miRNAs (miR 203, 350, 421, and 466i) that were similarly expressed at 3 hrs and 24 hrs of DES treat times. Twenty one genes matched between predicted target for 4 miRNAs and 118 genes expressed similarly. These genes have functions related to cell differentiation and cell cycle. Therefore, DES affects cellular function and induces toxicity in TM4 cells. In future studies, it is necessary to find more related functions and mechanisms of DES in the system. 相似文献
42.
Ei Tae Kim Lee Hoo Kim Jung Il Lee Hee Seung Chin 《Japanese journal of ophthalmology》2009,53(6):598-602
Background
To assess the nature, incidence, and risk factors of retinopathy associated with pegylated interferon and ribavirin combination therapy in chronic hepatitis C patients. 相似文献43.
PCBs with the highest vapor pressures (fewest chlorines) in Aroclors 1016, 1242, 1254 and 1268 were enriched in the vapor phase relative to the original Aroclor during volatilization from a glass surface for up to 8 hr. PCBs with the lowest vapor pressures (most highly chlorinated) were enriched in the corresponding residue. Thus, visual matching of gas chromatograms with those of Aroclor standards may not be sufficient to identify a specific Aroclor since the past history of a sample is often unknown. The enrichment also was detected using isomeric classes, but not using total chlorine content. The perchlorination method and the Webb-McCall method using all chromatographic peaks agreed quantitatively; this was not always so for the NIOSH multiple peaks and the Webb-McCall methods. 相似文献
44.
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
45.
A method for dynamic imaging in MRI is presented that enables the acquisition of a series of images with both high temporal and high spatial resolution. The technique, which is based on the projection reconstruction (PR) imaging scheme, utilizes distinct data acquisition and reconstruction strategies to achieve this simultaneous capability. First, during acquisition, data are collected in multiple undersampled passes, with the view angles interleaved in such a way that those of subsequent passes bisect the views of earlier ones. During reconstruction, these views are weighted according to a previously described k-space weighted image contrast (KWIC) technique that enables the manipulation of image contrast by selective filtering. Unlike conventional undersampled PR methods, the proposed dynamic KWIC technique does not suffer from low image SNR or image degradation due to streaking artifacts. The effectiveness of dynamic KWIC is demonstrated in both simulations and in vivo, high-resolution, contrast-enhanced imaging of breast lesions. 相似文献
46.
Jeong-Hoon Oh Keehyun Park Seung Joo Lee You Ree Shin Yun-Hoon Choung 《Otolaryngology--head and neck surgery》2007,136(1):87-91
OBJECTIVES: To analyze the clinical characteristics and treatment results between bilateral (bi-) and unilateral (uni-) sudden sensorineural hearing loss (SSNHL). STUDY DESIGN AND SETTING: A retrospective study. METHODS: Three hundred twenty-four patients with SSNHL were classified into two groups; simultaneous bi-SSNHL (n = 16) and uni-SSNHL (n = 308). We compared clinical characteristics, medical history, hearing level, and treatment results between the 2 groups. RESULTS: The incidence of bi-SSNHL was 4.9 percent of overall patients with SSNHL. Bi-SSNHL occurs more commonly in patients of older age, with preexisting diabetes mellitus, and lipid panel abnormalities compared with uni-SSNHL. Ten patients (62.5%) in the bi-SSNHL group showed hearing recovery in 1 or both ears compared with 56.5 percent of patients with uni-SSNHL. Only 12 (37.5%) of all 32 ears recovered in bi-SSNHL, which was significantly lower than in uni-SSNHL. CONCLUSION: Bi-SSNHL has a very low incidence and lower recovery rate than uni-SSNHL. Recognition of similarities and differences between bilateral and unilateral SSNHL can help in counseling and managing the patients. 相似文献
47.
Seok Hyun Cho Hyun Jung Min Hong Xiu Han Seung Sam Paik Kyung Rae Kim 《Otolaryngology--head and neck surgery》2006,135(3):404-408
OBJECTIVE: To evaluate the findings of computed tomography (CT) and histopathology of the bulla ethmoidalis as objective markers of bone remodeling in chronic rhinosinusitis (CRS). METHODS: Preoperative ostiomeatal unit (OMU) scans and histopathologic findings of the bulla ethmoidalis were performed on 23 patients (39 sides) undergoing endoscopic sinus surgery for CRS. Lund-Mackay scores and Hounsfield units (HU) of the bulla were checked in coronal CT scans. The pathologist graded the severities of the mucosal and bony changes in histopathology. Statistical analysis was performed using Mann-Whitney U test and Spearman correlation coefficient (r). RESULTS: The HU values of the bulla were significantly increased with higher Lund-Mackay scores in OMU CT (r = 0.405, P = 0.01). The bony grades in histopathology were significantly increased with higher mucosal grades (r = 0.821, P = 0.0001). These findings in CT scans and histopathology were well correlated with each other (r > 0.3, P < 0.05). CONCLUSION: HU may be a useful objective marker of bone remodeling in chronic rhinosinusitis. 相似文献
48.
Yang Hee Lee Ihn Rhan Lee Won Sick Won Chung Hee Park 《Archives of pharmacal research》1988,11(3):247-249
49.
Growth factor-dependent activation of the MAPK pathway in human pancreatic cancer: MEK/ERK and p38 MAP kinase interaction in uPA synthesis 总被引:3,自引:0,他引:3
Increased expression of the hepatocyte growth factor (HGF) receptor (c-met) and urokinase type plasminogen (uPA) correlated
with the development and metastasis of cancers. To investigate the role of HGF/c-met signaling on metastasis in cancer cells
stimulated with HGF, we examined the effects of a specific MEK1 inhibitor (PD98059) and a p38 MAP kinase inhibitor (SB203580)
on HGF-induced uPA expression in pancreatic cancer cell lines, L3.6PL and IMIM-PC2. Pretreatment of PD98059 decreased HGF-mediated
phosphorylation of extracellular receptor kinase (ERK), uPA secretion and expression of matrix metalloproteinases (MMP-2 and
MMP-9) in a dose-dependent manner. In contrast, SB203580 pretreatment increased HGF-stimulated ERK phosphorylation, uPA secretion
and expression of MMPs. SB203580 also reversed the inhibition of HGF-mediated ERK activation and uPA secretion in the PD98059-pretreated
cells. These results suggest that ERK activation by HGF might play important roles in the metastasis of pancreatic cancer
and the p38 MAPK pathway also involved in the HGF-mediated uPA secretion and metastasis by regulation of ERK pathway.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
50.
Immunocytochemical localization of zinc transporter 3 in the ependyma of the mouse spinal cord 总被引:2,自引:0,他引:2
We report, for the first time, the light microscopical and ultrastructural appearance of ZnT3-immunoreactivities in the ependymal cells of the central canal of the mouse spinal cord. Light microscopy revealed the presence of ZnT3-immunoreactive (Ir) ependymal cells in 1 microm thick epon sections stained by the ABC method. The ZnT3-Ir cells were observed at all levels of the spinal cord, but were a little more numerous in lumbosacral segments than in cervicothoracic segments. The ZnT3-Ir cells had large, ovoid nuclei with abundant cytoplasm, and protruded into the lumen of the central canal. Our ultrastructural findings suggest that the ZnT3-Ir ependymal cells possess secretory activity directed towards the central canal. We propose that they may play a role in the trans-ependymal mechanism responsible for zinc homeostasis between cerebrospinal fluid and the central area of the gray matter. 相似文献