全文获取类型
收费全文 | 1039篇 |
免费 | 34篇 |
国内免费 | 65篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 56篇 |
妇产科学 | 10篇 |
基础医学 | 85篇 |
口腔科学 | 36篇 |
临床医学 | 138篇 |
内科学 | 232篇 |
皮肤病学 | 23篇 |
神经病学 | 14篇 |
特种医学 | 244篇 |
外科学 | 46篇 |
综合类 | 29篇 |
预防医学 | 25篇 |
眼科学 | 14篇 |
药学 | 127篇 |
中国医学 | 2篇 |
肿瘤学 | 55篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 16篇 |
2014年 | 14篇 |
2013年 | 29篇 |
2012年 | 29篇 |
2011年 | 27篇 |
2010年 | 31篇 |
2009年 | 48篇 |
2008年 | 31篇 |
2007年 | 65篇 |
2006年 | 28篇 |
2005年 | 17篇 |
2004年 | 15篇 |
2003年 | 13篇 |
2002年 | 15篇 |
2001年 | 13篇 |
2000年 | 17篇 |
1999年 | 14篇 |
1998年 | 60篇 |
1997年 | 74篇 |
1996年 | 71篇 |
1995年 | 60篇 |
1994年 | 42篇 |
1993年 | 51篇 |
1992年 | 8篇 |
1991年 | 18篇 |
1990年 | 14篇 |
1989年 | 41篇 |
1988年 | 22篇 |
1987年 | 37篇 |
1986年 | 17篇 |
1985年 | 27篇 |
1984年 | 17篇 |
1983年 | 26篇 |
1982年 | 19篇 |
1981年 | 17篇 |
1980年 | 20篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1966年 | 2篇 |
1947年 | 1篇 |
排序方式: 共有1138条查询结果,搜索用时 0 毫秒
51.
52.
Piersma AH 《Toxicology letters》2004,149(1-3):147-153
Developmental toxicity testing according to current international guidelines involves exposure of pregnant animals, mostly rats and rabbits, and subsequent assessment of toxic effects in their fetuses. Alternative methods have been developed since the early 1980s. They include cell differentiation assays using either primary cell cultures or immortalized cell lines. At a higher integration level the development of organ anlagen in vitro has been employed in assays for developmental toxicity. The most complex assays in this area make use of isolated postimplantation rodent embryos which are cultured in vitro during the phase of major organogenesis. The possibilities for their application as toxicity screens have been investigated in various validation studies. The most elaborate validation study of embryotoxicity assays carried out to date included the embryonic stem cell test EST, the limb bud micromass MM, and whole embryo culture WEC. In each test 20 chemical compounds were tested in four independent laboratories. The results have shown a marked success in the reproducibility of results. The extrapolation of these results of a limited set of chemicals to a generalized judgment of the tests for the world of chemicals remains a matter for further discussion. 相似文献
53.
Luijten M Thomsen AR van den Berg JA Wester PW Verhoef A Nagelkerke NJ Adlercreutz H van Kranen HJ Piersma AH Sørensen IK Rao GN van Kreijl CF 《Nutrition and cancer》2004,50(1):46-54
Phytoestrogens such as isoflavonoids and lignans have been postulated as breast cancer protective constituents in soy and whole-grain cereals. We investigated the ability of isoflavones (IFs) and flaxseed to modulate spontaneous mammary tumor development in female heterozygous Tg.NK (MMTV/c-neu) mice. Two different exposure protocols were applied, either from 4 wk of age onward (postweaning) or during gestation and lactation (perinatal). In the postweaning exposure study, mice were fed IFs or flaxseed in a high-fat diet. In addition, flaxseed in a low-fat diet was tested. Postweaning exposure to IFs and flaxseed tended to accelerate the onset of mammary adenocarcinoma development, although tumor burden at necropsy was not changed significantly. Perinatal IF exposure resulted in enhanced mammary gland differentiation, but palpable mammary tumor onset was not affected. However, tumor burden at necropsy in the perinatal exposure study was significantly increased in the medium- and high-IF dose groups. Comparison of both exposure scenarios revealed a strongly accelerated onset of tumor growth after perinatal high-fat diet exposure compared with the low-fat diet. This study shows that breast cancer-modulating effects of phytoestrogens are dependent both on the background diet and on the timing of exposure in the life cycle. 相似文献
54.
Genschow E Scholz G Brown N Piersma A Brady M Clemann N Huuskonen H Paillard F Bremer S Becker K Spielmann H 《In vitro & molecular toxicology》2000,13(1):51-66
Since 1997 the National Center for Documentation and Evaluation of Alternative Methods to Animal Experiments, ZEBET, in Berlin, has been coordinating a validation study aimed at prevalidation and validation of three in vitro embryotoxicity tests, funded by the European Center for the Validation of Alternative Methods (ECVAM) at the Joint Research Center (JRC, Ispra, Italy). The tests use the cultivation of postimplantation rat whole embryos (WEC test), cultures of primary limb bud cells of rat embryos (micromass or, MM, test), and cultures of a pluripotent mouse embryonic stem cell line (embryonic stem cell test or EST). Each of the tests was performed in four laboratories under blind conditions. In the preliminary phase of the validation study 6 out of 20 test chemicals comprising different embryotoxic potential (non, weakly, and strongly embryotoxic) were tested. The results were used to define biostatistically based prediction models (PMs) to identify the embryotoxic potential of test chemicals for the WEC test and the MM test. The PMs developed with the results of the preliminary phase of the validation study (training set) will be evaluated with the results of the remaining 14 test chemicals (definitive phase) by the end of the study. In addition, the existing, improved PM (iPM) for the EST, which had been defined previously, was evaluated using the results of the preliminary phase of this study. Applying the iPM of the EST to the results of this study, in 79% of the experiments, chemicals were classified correctly according to the embryotoxic potential defined by in vivo testing. For the MM and the WEC test, the PMs developed during the preliminary phase of this validation study provided 81% (MM test) and 72% (WEC test) correct classifications. Because the PM of the WEC test took into account only parameters of growth and development, but not cytotoxicity data, a second PM (PM2) was developed for the WEC test by incorporating cytotoxicity data of the differentiated mouse fibroblast cell line 3T3, which was derived from the EST. This approach, which has previously never been used, resulted in an increase to 84% correct classifications in the WEC test. 相似文献
55.
Pneumocystis carinii pneumonia studied by gallium-67 scanning 总被引:1,自引:0,他引:1
The validity and reliability of gallium-67 (Ga-67) scanning for diagnosis and follow-up of Pneumocystis carinii pneumonia (PCP) were assessed in 34 patients thought to have pulmonary complications of acquired immunodeficiency syndrome (AIDS). Overall sensitivity was 94% and specificity 74%. Among patients with normal or equivocal chest radiographs at the time of admission, sensitivity was 86% and specificity 85%. The authors consider Ga-67 scanning a valid and reliable adjunct in the diagnosis of PCP in AIDS patients with respiratory symptoms when the chest radiograph is normal or equivocal. 相似文献
56.
葛根素对高血压患者血浆内皮素和一氧化氮的影响 总被引:29,自引:0,他引:29
目的:检测正常人与高血压病(EH)患者血浆内皮素、一气体氮的变化及葛根素对其的干预效应。方法:EH对照组口服苯磺酸氨氯地平5mg/d,或合和盐酸苯那普利10mg/d,每日一次,15d为一疗程。EH伍用治疗组同时合用5%GNS250ml+葛根素注射液400mg静滴,两组治疗前后检测血浆ET、NO水平变化。结果:EH各组血浆ET较正常人组均显著增高(P〈0.01),血浆NO水平及NO/ET比值除轻度E 相似文献
57.
58.
59.
Blood loss and replacement in total hip arthroplasty: a multicenter study. The Preoperative Autologous Blood Donation Study Group 总被引:1,自引:0,他引:1
To determine blood loss, the number of transfusions, and the hemoglobin levels achieved in patients via transfusion in the course of total hip arthroplasty, 324 patient records from 1987 through 1989 were reviewed at three university and three community hospitals. Calculated blood loss was 3.2 +/- 1.3 units in primary procedures and 4.0 +/- 2.1 units in revision procedures (mean +/- SD). Of 777 red cell units transfused, 455 (59%) were autologous units. Transfused patients received 2.0 +/- 1.8 units for primary procedures and 2.9 +/- 2.3 units for revision procedures (mean +/- SD). The maximum number of units given to 95 percent of the transfused patients was 4 for primary procedures and 6 for revision procedures. The mean postoperative hemoglobin level after all transfusions was 103 to 110 g per L, regardless of patient age group of physical status, autologous donor status, or hospital. No difference in length of hospital stay was observed for patients less than 65 years old with hemoglobin concentrations of 80 to 139 g per L at discharge. 相似文献
60.