全文获取类型
收费全文 | 15144篇 |
免费 | 919篇 |
国内免费 | 120篇 |
专业分类
耳鼻咽喉 | 159篇 |
儿科学 | 466篇 |
妇产科学 | 399篇 |
基础医学 | 2063篇 |
口腔科学 | 402篇 |
临床医学 | 1497篇 |
内科学 | 3081篇 |
皮肤病学 | 571篇 |
神经病学 | 871篇 |
特种医学 | 824篇 |
外科学 | 2432篇 |
综合类 | 193篇 |
现状与发展 | 1篇 |
一般理论 | 2篇 |
预防医学 | 676篇 |
眼科学 | 313篇 |
药学 | 1110篇 |
中国医学 | 152篇 |
肿瘤学 | 971篇 |
出版年
2023年 | 104篇 |
2022年 | 258篇 |
2021年 | 431篇 |
2020年 | 210篇 |
2019年 | 275篇 |
2018年 | 453篇 |
2017年 | 340篇 |
2016年 | 384篇 |
2015年 | 495篇 |
2014年 | 712篇 |
2013年 | 755篇 |
2012年 | 1085篇 |
2011年 | 1041篇 |
2010年 | 676篇 |
2009年 | 570篇 |
2008年 | 829篇 |
2007年 | 829篇 |
2006年 | 786篇 |
2005年 | 757篇 |
2004年 | 670篇 |
2003年 | 532篇 |
2002年 | 510篇 |
2001年 | 435篇 |
2000年 | 402篇 |
1999年 | 330篇 |
1998年 | 220篇 |
1997年 | 176篇 |
1996年 | 187篇 |
1995年 | 131篇 |
1994年 | 133篇 |
1993年 | 73篇 |
1992年 | 137篇 |
1991年 | 129篇 |
1990年 | 114篇 |
1989年 | 95篇 |
1988年 | 86篇 |
1987年 | 95篇 |
1986年 | 79篇 |
1985年 | 75篇 |
1984年 | 44篇 |
1983年 | 31篇 |
1982年 | 34篇 |
1981年 | 32篇 |
1980年 | 38篇 |
1979年 | 36篇 |
1977年 | 39篇 |
1976年 | 37篇 |
1975年 | 34篇 |
1974年 | 28篇 |
1972年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Improved survival for adenocarcinoma of the ampulla of Vater: fifty-five consecutive resections 总被引:12,自引:0,他引:12
Duffy JP Hines OJ Liu JH Ko CY Cortina G Isacoff WH Nguyen H Leonardi M Tompkins RK Reber HA 《Archives of surgery (Chicago, Ill. : 1960)》2003,138(9):941-8; discussion 948-50
HYPOTHESIS: After resection of an adenocarcinoma of the ampulla of Vater, certain clinical and pathologic characteristics influence long-term survival. DESIGN: Retrospective case series. SETTING: Major academic medical and pancreatic surgical center. PATIENTS: Fifty-five consecutive patients who underwent Whipple resection for ampullary adenocarcinoma from 1988 through 2001. INTERVENTIONS: Pylorus-preserving Whipple resection in 32 patients and standard Whipple resection in 23 patients. MAIN OUTCOME MEASURES: Postoperative survival. A multivariate Cox proportional hazards model was used to determine the effects of various factors on long-term survival after resection. RESULTS: There were no operative deaths, and all patients left the hospital. After a mean follow-up of 46.9 months, the overall 5-year Kaplan-Meier survival estimate was 67.7%. The median survival of the entire group has not yet been reached. Five-year postoperative survival estimates for node-negative (n = 32) and node-positive patients (n = 23) were 76.5% and 53.4%, respectively (P =.26). Patients whose tumors demonstrated perineural invasion (n = 12) had a 5-year survival estimate of 29.2% vs 78.8% for those whose did not (P<.001). On multivariate analysis, the absence of perineural invasion (P<.001) was an independent predictor of significantly improved postoperative survival. CONCLUSIONS: Compared with previous reports from our own and other centers, this series demonstrates improved postoperative survival by 10% to 20% in patients undergoing Whipple resection for adenocarcinoma of the ampulla of Vater. The reasons for this improved outcome are unclear, and the effect of adjuvant treatment cannot be determined from this analysis. The major factor associated with prolonged survival was the absence of perineural invasion in the resected tumor specimen. 相似文献
992.
Polyethylene wear in total hip prostheses: the influence of direction of linear wear on volumetric wear determined from radiographic data 总被引:1,自引:0,他引:1
Kosak R Antolic V Pavlovcic V Kralj-Iglic V Milosev I Vidmar G Iglic A 《Skeletal radiology》2003,32(12):679-686
Purpose To develop a new mathematical model for calculating the volumetric wear of polyethylene cups from known values of the radius of the prosthesis head, the extent of linear wear and the direction of linear wear determined from standard antero-posterior radiographs.Method A new mathematical model was developed. The results of this new mathematical model were compared with the results obtained using the standard, frequently used mathematical model, which takes into consideration only the radius of the prosthesis head and the extent of linear wear of the polyethylene cups. The results of both mathematical models were further compared with the results obtained by direct measurement of volumetric wear using the fluid displacement method.Results Comparison of the mathematical models shows that the average volumetric wear calculated using the new mathematical model is 8.5% smaller than the average volumetric wear determined by the fluid displacement method, while the average volumetric wear calculated by standard mathematical model is 17.5% higher. The results of the new mathematical model are, thus, notably less biased than those of the standard one.Conclusion In calculating the volumetric wear from antero-posterior radiographs, not only the radius of the prosthesis head and the extent of the linear wear but also the direction of the latter has to be considered. 相似文献
993.
Boo-Kyung Han Yeon Hyeon Choe Young-Hyeh Ko Seok-Jin Nam Jung-Han Kim Jung-Hyun Yang 《Korean journal of radiology》2003,4(4):217-223
Objective
To determine, by means of long-term follow-up evaluation, the outcome and accuracy of stereotactic core-needle biopsy (SCNB) of non-mass calcifications observed at mammography, and to analyze the factors contributing to false-negative findings.Materials and Methods
Using a 14-gauge needle, SCNB was performed in cases involving 271 non-mass calcified lesions observed at mammography in 267 patients aged 23-72 (mean, 47) years. We compared the SCNB results with those of long-term follow-up which included surgery, mammography performed for at least six months, and reference to Korean Cancer Registry listings. We investigated the retrieval rate for calcifications observed at specimen mammography and histologic evaluation, and determined the incidence rate of cancer, sensitivity, and the underestimation rate for SCNB. False-negative cases were evaluated in terms of their mammographic findings, the effect of the operators'' experience, and the retrieval rate for calcifications.Results
For specimen mammography and histologic evaluation of SCNB, the retrieval rate for calcifications was, respectively, 84% and 77%. At SCNB, 54 of 271 lesions (19.9%) were malignant [carcinoma in situ, 45/54 (83%)], 16 were borderline, and 201 were benign. SCNB showed that the incidence of cancer was 5.0% (6/120) in the benign mammographic category and 31.8% (48/151) in the malignant category. The findings revealed by immediate surgery and by long-term follow-up showed, respectively, that the sensitivity of SCNB was 90% and 82%. For borderline lesions, the underestimation rate was 10%. For false-negative cases, which were more frequent among the first ten cases we studied (p = 0.01), the most frequent mammographic finding was clustered amorphous calcifications. For true-negative and false-negative cases, the retrieval rate for calcifications was similar at specimen mammography (83% and 67%, respectively; p = 0.14) and histologic evaluation (79% and 75%, respectively; p = 0.47).Conclusion
In this study group, most diagnosed cancers were in-situ lesions, and long-term follow-up showed that the sensitivity of SCNB was 82%. False-negative findings were frequent during the operators'' learning period. 相似文献994.
995.
Indefinite islet protection from autoimmune destruction in nonobese diabetic mice by agarose microencapsulation without immunosuppression 总被引:6,自引:0,他引:6
Kobayashi T Aomatsu Y Iwata H Kin T Kanehiro H Hisanaga M Ko S Nagao M Nakajima Y 《Transplantation》2003,75(5):619-625
BACKGROUND: The recurrence of autoimmunity and allograft rejection act as major barriers to the widespread use of islet transplantation as a cure for type 1 diabetes. The aim of this study was to evaluate the feasibility of immunoisolation by use of an agarose microcapsule to prevent autoimmune recurrence after islet transplantation. METHODS: Highly purified islets were isolated from 6- to 8-week-old prediabetic male nonobese diabetic (NOD) mice and microencapsulated in 5% agarose hydrogel as a semipermeable membrane. Islet function was evaluated by a syngeneic islet transplantation model, in which islets were transplanted into spontaneously diabetic NOD mice. RESULTS: The nonencapsulated islet grafts were destroyed and diabetes recurred within 2 weeks after transplantation in all 12 mice. In contrast, 13 of the 16 mice that underwent transplantation with microencapsulated islets maintained normoglycemia for more than 100 days after islet transplantation. Histologic examination of the nonencapsulated islet grafts showed massive mononuclear cellular infiltration with beta-cell destruction. In contrast, the microencapsulated islets showed well-granulated beta cells with no mononuclear cellular infiltration around the microcapsules or in the accompanying blood capillaries between the microcapsules. CONCLUSIONS: Agarose microcapsules were able to completely protect NOD islet isografts from autoimmune destruction in the syngeneic islet transplantation model. 相似文献
996.
Concurrent induction of T-cell activation and apoptosis of osteosarcoma cells by adenovirus-mediated B7-1/Fas chimeric gene transfer 总被引:3,自引:0,他引:3
Tsuji H Kawaguchi S Wada T Nagoya S Inobe M Yagita H Okumura K Yamashita T Uede T 《Cancer gene therapy》2003,10(9):717-725
To establish an effective B7-based gene therapy against osteosarcoma, we transferred B7-1/Fas chimeric gene adenovirally into poorly immunogenic osteosarcoma cells. We found that adenovirus-mediated rat B7-1/Fas gene transfer induced (i) expression of rat B7-1/Fas chimeric molecules in osteosarcoma cells, (ii) activation of murine T cells, (iii) apoptosis of murine osteosarcoma cells in the presence of anti-rat B7-1 mAb in vitro, and (iv) therapeutic effects more prominently than B7-1 gene transfer on the development of pulmonary metastasis and survival of mice. These findings collectively support the therapeutic value of adenovirus-mediated B7-1/Fas gene transfer on poorly immunogenic osteosarcoma, which is resistant to a treatment protocol using transduction of B7-1 alone. 相似文献
997.
We describe a rare case of peritonitis caused by an unusual fungus, Trichoderma sp., in a patient on continuous ambulatory peritoneal dialysis. Management of the patient consisted of Tenckhoff catheter removal and antifungal chemotherapy, but the patient died. 相似文献
998.
Five new prenylflavonoids, artocommunols CA (1), CB (2), CC (3), CD (4), and CE (5), were isolated from the cortex of the roots of Artocarpus communis, along with the known compound cyclomorusin. The structures of 1-5 were determined by spectral methods. 相似文献
999.
Secoiridoid glucosides with free radical scavenging activity from the leaves of Syringa dilatata 总被引:1,自引:0,他引:1
Activity-guided fractionation of the EtOAc and MeOH extract of the leaves of Syringa dilatata NAKAI furnished one free radical scavenger, the secoiridoid glucoside oleuropein together with ligstroside and an iridoid glucoside, syringopicroside. Oleuropein interacted with the stable free radical, 1,1-diphenyl-2-picrylhydrazyl (DPPH), and showed an IC(50) value of 40.4 microM. L-Ascorbic acid as a positive control showed an IC(50) value of 50.3 microM. 相似文献
1000.
This study was carried out to investigate the protective effect of an aqueous extract from the root of Rhodiola sachalinensis (RSE) on liver injury induced by repetitive administration of carbon tetrachloride in rats. RSE was given orally to rats at doses of 50, 100 or 200 mg/kg throughout the carbon tetrachloride treatment for 28 days. In rats treated with carbon tetrachloride, the levels of hydroxyproline and malondialdehyde (MDA) in the liver, and serum enzyme activities were significantly increased. RSE treatment significantly reduced the levels of liver hydroxyproline and MDA, and serum enzyme activities, in accordance with improved histological findings. Immunohistological findings indicated RSE treatment inhibited hepatic stellate cell activation, which is a major step for collagen accumulation during liver injury. These data suggest that RSE protects the liver from repetitive injury induced by carbon tetrachloride in rats. 相似文献