全文获取类型
收费全文 | 1776篇 |
免费 | 115篇 |
国内免费 | 59篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 59篇 |
妇产科学 | 30篇 |
基础医学 | 243篇 |
口腔科学 | 23篇 |
临床医学 | 202篇 |
内科学 | 295篇 |
皮肤病学 | 18篇 |
神经病学 | 164篇 |
特种医学 | 178篇 |
外科学 | 207篇 |
综合类 | 94篇 |
预防医学 | 93篇 |
眼科学 | 81篇 |
药学 | 137篇 |
中国医学 | 22篇 |
肿瘤学 | 96篇 |
出版年
2023年 | 11篇 |
2022年 | 16篇 |
2021年 | 42篇 |
2020年 | 12篇 |
2019年 | 25篇 |
2018年 | 23篇 |
2017年 | 15篇 |
2016年 | 31篇 |
2015年 | 32篇 |
2014年 | 43篇 |
2013年 | 75篇 |
2012年 | 86篇 |
2011年 | 77篇 |
2010年 | 53篇 |
2009年 | 46篇 |
2008年 | 69篇 |
2007年 | 117篇 |
2006年 | 72篇 |
2005年 | 74篇 |
2004年 | 77篇 |
2003年 | 74篇 |
2002年 | 62篇 |
2001年 | 71篇 |
2000年 | 74篇 |
1999年 | 60篇 |
1998年 | 42篇 |
1997年 | 53篇 |
1996年 | 42篇 |
1995年 | 46篇 |
1994年 | 30篇 |
1993年 | 36篇 |
1992年 | 48篇 |
1991年 | 37篇 |
1990年 | 30篇 |
1989年 | 38篇 |
1988年 | 36篇 |
1987年 | 23篇 |
1986年 | 21篇 |
1985年 | 25篇 |
1984年 | 6篇 |
1983年 | 10篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 16篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 15篇 |
1976年 | 10篇 |
1975年 | 7篇 |
1970年 | 1篇 |
排序方式: 共有1950条查询结果,搜索用时 15 毫秒
51.
52.
Li Lou Shu Wei Liu Zhen Mei Zhao Pheng Ann Heng Yu Chun Tang Zheng Ping Li Yong Ming Xie Yim Pan Chui 《Surgical and radiologic anatomy : SRA》2009,31(10):763-768
Three-dimensional (3D) reconstruction of intrahepatic vessels is very useful in visualizing the complex anatomy of hepatic
veins and intrahepatic portal vein. It also provides a 3D anatomic basis for diagnostic imaging and surgical operation on
the liver. In the present study, we built a 3D digitized model of hepatic veins and intrahepatic portal vein based on the
coronal sectional anatomic dataset of the liver. The dataset was obtained using the digital freezing milling technique. The
pre-reconstructed structures were identified and extracted, and then were segmented by the method of manual intervention.
The digitized model of hepatic veins and intrahepatic portal vein was established using 3D medical visualization software.
This model facilitated a continuous and dynamic displaying of the hepatic veins and intrahepatic portal vein at different
orientations, which demonstrated the complicated relationship of adjacent hepatic veins and intrahepatic portal vein realistically
in the 3D space. This study indicated that high-quality 2D images, precise data segmentation, and suitable 3D reconstruction
methods ensured the reality and accuracy of the digital visualized model of hepatic veins and intrahepatic portal vein. 相似文献
53.
Du AT Schuff N Chao LL Kornak J Jagust WJ Kramer JH Reed BR Miller BL Norman D Chui HC Weiner MW 《Neurobiology of aging》2006,27(5):733-740
The effects of age, subcortical vascular disease, apolipoprotein E (APOE) epsilon4 allele and hypertension on entorhinal cortex (ERC) and hippocampal atrophy rates were explored in a longitudinal MRI study with 42 cognitively normal (CN) elderly subjects from 58 to 87 years old. The volumes of the ERC, hippocampus, and white matter hyperintensities (WMH) and the presence of lacunes were assessed on MR images. Age was significantly associated with increased atrophy rates of 0.04+/-0.02% per year for ERC and 0.05+/-0.02% per year for hippocampus. Atrophy rates of hippocampus, but not that of ERC increased with presence of lacunes, in addition to age. WMH, APOE epsilon4 and hypertension had no significant effect on atrophy rates. In conclusion, age and presence of lacunes should be taken into consideration in imaging studies of CN subjects and AD patients to predict AD progression and assess the response to treatment trials. 相似文献
54.
A single-chain antibody fragment (scFv) was constructed from a hybridoma antibody that binds to phosphorylcholine (PC) only when this hapten is presented in the form of the immunizing antigen (derived from Trichinella) but not when it is presented on other carriers (as found, for example, in pneumococcal capsules). The scFv derivative was found to lack this carrier specificity as it bound indiscriminately, but specifically, to the various PC-associated antigens, and exhibits a two-fold lower affinity (3.5x10(5)M(-1)) for nitrophenyl-PC than the native antibody. The findings suggest that the scFv combining site is different in fine structure from that of the native antibody. 相似文献
55.
Induction of B cell apoptosis by co-cross-linking CD23 and sIg involves aberrant regulation of c-myc and is inhibited by bcl-2 总被引:2,自引:0,他引:2
Campbell KA; Studer EJ; Kilmon MA; Lees A; Finkelman F; Conrad DH 《International immunology》1997,9(8):1131-1140
A novel system to study the effects of co-cross-linking CD23/FceRII and sIg
on murine B lymphocytes utilizes a highly multivalent form of anti- Ig
prepared by covalently linking anti-Ig antibodies to a DNP-dextran
backbone. CD23-sIg co-cross-linking is accomplished by the addition of
DNP-specific monoclonal IgE. Previous studies demonstrated that co-
cross-linking CD23 and sIg significantly inhibited mouse B cell
proliferation, especially at high doses of the multivalent anti-Ig.
Interestingly, examination of early activation signals reveals no
difference in B cells subjected to co-cross-linking conditions as compared
to B cells activated with anti-Ig alone. Total cellular protein tyrosine
phosphorylation levels are unchanged by co-cross- linking. Analysis of B
cell mRNA reveals that co-cross-linking the receptors does not alter the
expression levels of ornithine decarboxylase 8 h after stimulation as
compared to the controls. In contrast, levels of the proto-oncogene c-myc
were significantly elevated 1 h after inducing B cell activation under
co-cross-linking conditions. However, it remains unclear whether this
aberrant c-myc regulation plays any role in inducing apoptosis. In
addition, on day 3 after stimulation, the co-cross-linking of CD23 and sIg
resulted in the formation of apoptotic B cells, determined by both
photomicroscopy of the B cell cultures and FACS analysis of B cell nuclei.
B cells obtained from bcl-2 transgenic mice proliferated as well as
controls, and failed to undergo apoptosis when CD23 and sIg were
co-cross-linked on their surface. These studies indicate that
co-cross-linking of CD23 with B cell sIg inhibits B cell proliferation by a
mechanism that is distinct from that seen by co-cross-linking of the Fc
gamma RII and sIg. In addition, these results suggest a means by which
antigen- specific IgE can down-regulate additional B cell activation and
IgE synthesis.
相似文献
56.
Endosalpingiosis, a microscopic lesion composed of ectopic Fallopian tube epithelium, frequently involves the peritoneum and lymph nodes in patients with ovarian serous borderline tumour or low-grade serous carcinoma, but its pathogenic significance remains unclear. Using laser-capture microdissection and droplet digital PCR, we investigated whether endosalpingiosis harbours the driver mutations in BRAF and KRAS that characterise ovarian low-grade serous neoplasms. Somatic mutations were detected in 14 (33%) of 43 endosalpingiotic lesions analysed. Of 21 women with endosalpingiosis associated with a synchronous or metachronous ovarian low-grade serous tumour, mutations were identified in endosalpingiotic lesions from 11 (52%) women, with most cases (10/11, 91%) demonstrating identical mutations in both tumour and endosalpingiosis. In contrast, of 13 cases of endosalpingiosis not associated with an ovarian tumour, only one harboured a KRAS mutation. The proliferative activity as assessed by Ki-67 immunohistochemistry was lower in endosalpingiosis than in low-grade serous tumours, and endosalpingiosis with either a BRAF or KRAS mutation had a significantly lower Ki-67 index than those without. Ectopic expression of KRASG12V in Fallopian tube epithelial cells led to ERK phosphorylation, p21 induction, growth arrest and cellular senescence. In conclusion, we demonstrate that endosalpingiosis represents an interesting example of cancer driver mutations in deceptively normal-appearing cells, which may be prone to neoplastic transformation upon bypass of endogenous oncosuppressive mechanisms. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. 相似文献
57.
Comparison of LightCycler-based PCR,COBAS amplicor CMV monitor,and pp65 antigenemia assays for quantitative measurement of cytomegalovirus viral load in peripheral blood specimens from patients after solid organ transplantation 总被引:2,自引:0,他引:2 下载免费PDF全文
Pang XL Chui L Fenton J LeBlanc B Preiksaitis JK 《Journal of clinical microbiology》2003,41(7):3167-3174
In order to evaluate the LightCycler-based PCR (LC-PCR) as a diagnostic assay technique, a classical pp65 antigenemia assay and the commercially available COBAS Amplicor CMV Monitor (CACM) assay were compared to the LC-PCR assay for the detection and quantitation of cytomegalovirus (CMV) load in 404 parallel specimens of peripheral blood from 66 patients after solid organ transplantation. A good correlation existed among these three assays (r congruent with 0.6, P < 0.0001). The LC-PCR assay was the most sensitive (54% of specimens positive) compared to the CACM (48.6%) and the pp65 antigenemia (26%) assays. The LC-PCR assay detected all samples found positive by using both the CMV pp65 antigenemia assay and the CACM assay. The LC-PCR also had the widest dynamic range (from 250 to 10(7) DNA copies/ml of plasma). No cross-reactions were found among CMV and Epstein-Barr virus, varicella-zoster virus, or herpes simplex virus in the LC-PCR by using amplification with specifically designed primer pairs. Precision, expressed as the coefficient of variation, was <3% with standard DNA from cell cultures and between 6.55 and 14.1% with clinical specimens in repeat LC-PCR runs. One run of the LC-PCR took half of the time required for the semiautomated CACM procedure. Because of its sensitivity, specificity, cost-effectiveness, and simplicity, the LC-PCR assay could replace the pp65 antigenemia and the CACM assays as the preferred technique for the surveillance, diagnosis, and monitoring of response of CMV diseases in high-risk populations. 相似文献
58.
59.
Comparison of methods for measuring longitudinal brain change in cognitive impairment and dementia 总被引:4,自引:0,他引:4
Cardenas VA Du AT Hardin D Ezekiel F Weber P Jagust WJ Chui HC Schuff N Weiner MW 《Neurobiology of aging》2003,24(4):537-544
PURPOSE: The goal of this project was to compare MRI measures of hippocampal, entorhinal cortex (ERC), and whole brain longitudinal change in cognitively normal elderly controls (C), non-demented subjects with cognitive impairment (CI), and demented (D) subjects. METHODS: 16 C, 6 CI, and 7 D subjects of comparable age were studied with MRI twice, at least 1 year apart. Longitudinal change in total brain size was measured by several methods, including computerized segmentation, non-linear warping, and change in the fluid/tissue boundaries between cerebrospinal fluid (CSF) and brain. Change in hippocampal volume was measured by semi-automated methods, and ERC volumes were manually measured. RESULTS: The annual rate of atrophy was greater in D versus C and D versus CI for cortical gray matter (cGM) (P=0.009 and 0.002), hippocampus (P=0.0001 and 0.002), and for the change in the fluid/tissue boundary (P=0.03 and 0.03). The annual rate of atrophy of ERC was greater in both CI and D versus C (P=0.01 and 0.0002). No significant differences between groups were found using non-linear warping. CONCLUSIONS: In CI, the greatest annual rates of atrophy were in ERC, while in D the greatest annual rates of atrophy were in hippocampus and cortex. Progressive ERC atrophy was observed with a greater degree of cognitive impairment, while hippocampal and cortical atrophy were only observed in demented subjects. 相似文献
60.
Emmanuel Fulgence Drabo Douglas Barthold Geoffrey Joyce Patricia Ferido Helena Chang Chui Julie Zissimopoulos 《Alzheimer's & dementia》2019,15(11):1402-1411
IntroductionThere is insufficient understanding of diagnosis of etiologic dementia subtypes and contact with specialized dementia care among older Americans.MethodsWe quantified dementia diagnoses and subsequent health care over five years by etiologic subtype and physician specialty among Medicare beneficiaries with incident dementia diagnosis in 2008/09 (226,604 persons/714,015 person-years).ResultsEighty-five percent of people were diagnosed by a nondementia specialist physician. Use of dementia specialists within one year (22%) and five years (36%) of diagnosis was low. “Unspecified” dementia diagnosis was common, higher among those diagnosed by nondementia specialists (33.2%) than dementia specialists (21.6%). Half of diagnoses were Alzheimer's disease.DiscussionAscertainment of etiologic dementia subtype may inform hereditary risk and facilitate financial and care planning. Use of dementia specialty care was low, particularly for Hispanics and Asians, and associated with more detection of etiological subtype. Dementia-related professional development for nonspecialists is urgent given their central role in dementia diagnosis and care. 相似文献