全文获取类型
收费全文 | 8432篇 |
免费 | 956篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 59篇 |
儿科学 | 259篇 |
妇产科学 | 202篇 |
基础医学 | 1147篇 |
口腔科学 | 192篇 |
临床医学 | 1198篇 |
内科学 | 1730篇 |
皮肤病学 | 99篇 |
神经病学 | 608篇 |
特种医学 | 244篇 |
外科学 | 1374篇 |
综合类 | 189篇 |
一般理论 | 9篇 |
预防医学 | 902篇 |
眼科学 | 101篇 |
药学 | 536篇 |
肿瘤学 | 550篇 |
出版年
2021年 | 110篇 |
2020年 | 88篇 |
2019年 | 108篇 |
2018年 | 178篇 |
2017年 | 128篇 |
2016年 | 125篇 |
2015年 | 143篇 |
2014年 | 195篇 |
2013年 | 287篇 |
2012年 | 378篇 |
2011年 | 375篇 |
2010年 | 193篇 |
2009年 | 230篇 |
2008年 | 365篇 |
2007年 | 386篇 |
2006年 | 408篇 |
2005年 | 356篇 |
2004年 | 354篇 |
2003年 | 309篇 |
2002年 | 340篇 |
2001年 | 298篇 |
2000年 | 275篇 |
1999年 | 227篇 |
1998年 | 115篇 |
1997年 | 100篇 |
1996年 | 88篇 |
1995年 | 82篇 |
1994年 | 67篇 |
1993年 | 92篇 |
1992年 | 198篇 |
1991年 | 178篇 |
1990年 | 204篇 |
1989年 | 167篇 |
1988年 | 155篇 |
1987年 | 149篇 |
1986年 | 140篇 |
1985年 | 149篇 |
1984年 | 121篇 |
1983年 | 85篇 |
1981年 | 63篇 |
1979年 | 116篇 |
1978年 | 82篇 |
1977年 | 62篇 |
1976年 | 75篇 |
1975年 | 74篇 |
1974年 | 86篇 |
1973年 | 82篇 |
1972年 | 87篇 |
1970年 | 66篇 |
1969年 | 81篇 |
排序方式: 共有9399条查询结果,搜索用时 15 毫秒
61.
62.
63.
Molecular alterations in atypical adenomatous hyperplasia occurring in benign and cancer-bearing lungs. 总被引:1,自引:0,他引:1
Joel F Gradowski Geeta S Mantha Jennifer L Hunt Sanja Dacic 《Diagnostic molecular pathology》2007,16(2):87-90
Atypical adenomatous hyperplasia (AAH) is considered to be a precursor lesion of the lung adenocarcinoma. Several genetic abnormalities have been reported in AAH associated with adenocarcinoma, but little is known about AAH associated with benign lung lesions. To address this we compared the molecular characteristics of AAH present in benign conditions to those coexisting with carcinoma. Seven cases of AAH from resected non-neoplastic lungs (AAH-B) and 12 cases from lungs resected for primary lung carcinoma (AAH-M) were analyzed for loss of heterozygosity (LOH) using 21 polymorphic microsatellite markers situated in proximity to known tumor suppressor genes on chromosomes 3p, 5q, 7p, 9p, 10q, and 17p. Direct DNA sequencing for K-ras mutation was also performed. There was a broad range of LOH in both groups. No LOH was identified in 3 cases (25%) of AAH-M, but all cases of AAH-B showed LOH (P=0.26). Six cases (50%) of AAH-M and 3 cases (43%) of AAH-B showed loss at 1 marker (P=0.99). LOH at 2 or more markers was identified in 3 (25%) cases of AAH-M and 4 (57%) cases of AAH-B (P=0.32). LOH was most frequently detected on chromosomes 3p and 10q in both groups. The difference in overall fractional allelic loss between the 2 groups did not reach statistical significance. K-ras mutations were not identified in either group. Our results showed a significant overlap in LOH patterns between AAH with or without coexistent lung malignancy. Therefore, AAH may represent a smoking induced low-grade neoplastic lesion that may be a precursor lesion of only a subset of invasive lung adenocarcinoma. 相似文献
64.
65.
Kathleen Rooney Caroline Hunt Leanne Humphreys David Harding Miriam Mullen John Kearney 《Clinical psychology & psychotherapy》2005,12(2):97-111
Prior reports suggest an ambivalence regarding treatment in individuals with Post-Traumatic Stress Disorder (PTSD). A model that accommodates such ambivalence is the Transtheoretical Model of Behavior Change (TTM, also known as the Stages-of-Change Model). Fifty veterans presenting for treatment completed self-report measures (94% response rate) that assessed disorder variables and constructs relating to the TTM. While the relationships between the components of each specific construct were found to be consistent with the findings of other studies and a number of predicted relationships between variables were confirmed, many results were inconsistent with the TTM. Notwithstanding questions about the suitability of the self-report measures, the unique characteristics of the veteran sample and the small sample size, the results suggest that the assumptions of the TTM were not met in veterans with PTSD. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
66.
An evaluation of commercial radioisotope methods for the determination of folate and vitamin B12. 下载免费PDF全文
D W Dawson I W Delamore D I Fish T A Flaherty A H Gowenlock L P Hunt K Hyde J E MacIver J A Thornton H M Waters 《Journal of clinical pathology》1980,33(3):234-242
Five commercial kits for the determination of folate and six kits for the determination of vitamin B12 were investigated. Their performance has been compared with microbiological methods for the two vitamins and with a non-commercial radioisotopic method for B12. The results show the importance of the determination of the reference range for an individual laboratory for each method. The precision of the kits varied appreciably, as did their performance using specimens from patients with different haematological disorders. In particular, certain kits failed to detect all patients with pernicious anaemia. The relative accuracy of the kits was assessed. Various factors which should be taken into account in the final selection of a satisfactory kit are discussed. 相似文献
67.
AIMS: To study the expression of Ki-67 and cytokeratin 20 (CK20) in a group of hyperplastic polyps (including a group with "atypical" features) with the aim of determining whether upper crypt Ki-67 staining and lower crypt CK20 staining correlated with these atypical features, as assessed by light microscopy. METHODS: Fifty seven formalin fixed, paraffin wax embedded hyperplastic colorectal polyps from 53 patients were selected on histological grounds; these comprised 26 typical polyps and 31 with atypical features, which included nuclear hyperchromatism, basal crowding, and increased mitotic activity. These polyps were examined using a standard immunohistochemical method with antibodies against CK20 and Ki-67. Comparisons were made with normal mucosa, adenomatous polyps, and carcinomas. RESULTS: Of the 26 typical polyps, 17 showed the usual pattern of lower crypt Ki-67 and upper crypt CK20 staining; one with upper crypt Ki-67 staining but normal surface CK20 staining; seven with Ki-67 confined to the lower half of crypts but with scattered lower crypt CK20; and one with both upper crypt Ki-67 staining, together with scattered CK20 basal staining. Of the 31 polyps with atypical features, 11 showed the usual staining pattern of lower crypt Ki-67 staining and surface staining with CK20; two showed Ki-67 staining extending into the upper half of crypts, but with a normal surface staining with CK20; 14 showed Ki-67 confined to the lower half of crypts, but scattered lower crypt staining with CK20; and four showed upper crypt Ki-67 staining together with scattered CK20 lower crypt staining. CONCLUSIONS: The normal pattern of lower crypt Ki-67 and upper crypt CK20 was seen in 28 of the 57 hyperplastic polyps and, in general, this corresponded with standard light microscopic appearances. Twenty one of the 57 polyps showed lower crypt mosaic CK20 staining, which in general corresponded with basal abnormalities on light microscopy, although seven specimens had normal appearances. Two smaller subsets emerged, one showing upper crypt Ki-67 staining in the presence of normal CK20 expression (three cases) and another in which a combination of lower crypt CK20 and upper crypt Ki-67 expression was seen (five cases). This last pattern was similar to that of neoplastic polyps and raises the possibility that a subgroup of hyperplastic polyps exists that may be a variant with malignant potential. Further studies with markers of mismatch repair genes and K-ras mutations may help to clarify this issue. 相似文献
68.
Evaluation of commercially available acridinium ester-labeled chemiluminescent DNA probes for culture identification of Blastomyces dermatitidis, Coccidioides immitis, Cryptococcus neoformans, and Histoplasma capsulatum. 总被引:3,自引:3,他引:3 下载免费PDF全文
Four commercially available acridinium ester-labeled DNA probes directed against rRNA were evaluated for their ability to identify Blastomyces dermatitidis, Coccidioides immitis, Histoplasma capsulatum, and Cryptococcus neoformans in culture. rRNA was extracted by sonication of 1- to 2-mm2 portions of cultures of fungi in two chaotropic reagents with glass beads. Following a heat inactivation step, the extracts were hybridized in solution with probes specific for each pathogen. The acridinium ester reporter moiety of nonhybridized probe was selectively hydrolyzed, and chemiluminescence of specific DNA:RNA hybrids was quantitated in relative light units with a luminometer. A positive identification required a relative light unit value of > or = 50,000. Sensitivity and specificity of the probes were determined by probing cultures of the respective pathogenic fungi (target) and nontarget fungi. Both mycelial and yeast forms of the dimorphic fungi (B. dermatitidis and H. capsulatum) were tested. For B. dermatitidis, sensitivity and specificity were 87.8 and 100%, respectively (74 target and 219 nontarget fungi tested). For C. immitis, sensitivity and specificity were 99.2 and 100%, respectively (122 target and 164 nontarget fungi tested). For H. capsulatum, sensitivity and specificity were 100 and 100%, respectively (86 target and 154 nontarget fungi tested). For C. neoformans, sensitivity and specificity were 97 and 100%, respectively (100 target and 230 nontarget fungi tested). For B. dermatitidis, C. immitis, and C. neoformans, repeat testing increased the respective sensitivities to 97.3, 100, and 100%. The high sensitivities and specificities of the probes, the relatively short time (less than 1 h) required to perform the assay, and the availability of standardized reagent kits make the acridinium ester-labeled DNA probes well suited to laboratories in need of a rapid method to identify these fungal pathogens. Further, use of the probes to identify pathogenic fungi as soon as colonies appear on primary recovery media significantly shortens the time to reporting. 相似文献
69.
Localization of IFN-gamma-activated Stat1 and IFN regulatory factors 1 and 2 in breast cancer cells.
Judith M Connett Steven R Hunt Suzanne M Hickerson Susan J Wu Gerard M Doherty 《Journal of interferon & cytokine research》2003,23(11):621-630
The aim of the present work was to evaluate the induction and localization of Stat1, interferon (IFN) regulatory factor-1 (IRF-1), and IRF-2 after IFN-gamma exposure of human breast cancer cell lines, SKBR3, MDA468, MCF7, and BT20. Results from growth assays, Western staining, electrophoretic mobility shift assay (EMSA), and immunohistochemical staining were collated to test our hypothesis that immunohistochemical analysis of Stat1, IRF-1, and IRF-2 would provide additional information about the functionality of the IFN-gamma signaling pathway in human tumor lines. EMSA results showed that in each of four cell lines, Stat1 expression was increased and demonstrated functional activity after IFN-gamma stimulation. Western and EMSA analysis showed upregulation of IRF-1 but not IRF-2 in each cell line. Confocal microscopy of cells stained for Stat1, IRF-1, and IRF-2 confirmed the results and also provided novel information about the intracellular localization of proteins and intercellular variations in responses. The proportion of cells with IRF-1 stimulation and translocation was positively correlated with the IFN-gamma growth suppression in vitro. In conclusion, using four independent assays, we have demonstrated that heterogeneity in IFN-gamma-mediated upregulation of signal transduction proteins can be detected in vitro and that these differences can explain distinct cellular growth effects. 相似文献
70.
Individual preparations of affinity purified anti-F(ab')2 antibodies and anti-Fc antibodies isolated from the sera of patients with rheumatoid arthritis (RA), were examined for reactivity with the Fab and Fc fragments of human IgG. Western blot assays demonstrated specific interaction of affinity-purified anti-Fab antibodies with both Fab and Fc molecules. Approximately one-half of the anti-Fab antibody preparations studied contained IgG antibodies reactive with Fab and Fc fragments in ELISA, suggesting the existence of naturally occurring epibody-like autoantibodies in these patients. Thirteen of 14 affinity-purified anti-Fc antibody preparations contained IgG cross-reactive with Fab molecules in ELISA. Double-adsorption assays on affinity columns demonstrated that a minimum of 14%, and possibly as much as 50%, of the IgG anti-Fab antibodies reacted with the Fc of IgG. Conversely, a minimum of 12%, and possibly as much as 70%, of the IgG anti-Fc antibodies reacted with IgG Fab molecules. Anti-Fab antibodies isolated from non-RA individuals also exhibited anti-Fc reactivity in ELISA, demonstrating the presence of these dual-reactive antibodies in other autoimmune and normal individuals. These studies establish the presence of naturally occurring IgG autoantibodies reactive with both the Fab and Fc fragments of human IgG. Their existence emphasizes the potential of anti-immunoglobulin antibodies to recognize a multiplicity of antigens, possibly including other members of the immunoglobulin supergene family. 相似文献