全文获取类型
收费全文 | 15281篇 |
免费 | 1381篇 |
国内免费 | 459篇 |
专业分类
耳鼻咽喉 | 88篇 |
儿科学 | 136篇 |
妇产科学 | 515篇 |
基础医学 | 1079篇 |
口腔科学 | 337篇 |
临床医学 | 2031篇 |
内科学 | 843篇 |
皮肤病学 | 77篇 |
神经病学 | 744篇 |
特种医学 | 549篇 |
外科学 | 796篇 |
综合类 | 2890篇 |
一般理论 | 5篇 |
预防医学 | 2455篇 |
眼科学 | 142篇 |
药学 | 2226篇 |
59篇 | |
中国医学 | 1893篇 |
肿瘤学 | 256篇 |
出版年
2024年 | 74篇 |
2023年 | 374篇 |
2022年 | 602篇 |
2021年 | 851篇 |
2020年 | 800篇 |
2019年 | 594篇 |
2018年 | 606篇 |
2017年 | 684篇 |
2016年 | 691篇 |
2015年 | 645篇 |
2014年 | 1227篇 |
2013年 | 1590篇 |
2012年 | 1191篇 |
2011年 | 1144篇 |
2010年 | 838篇 |
2009年 | 728篇 |
2008年 | 757篇 |
2007年 | 655篇 |
2006年 | 570篇 |
2005年 | 450篇 |
2004年 | 369篇 |
2003年 | 302篇 |
2002年 | 225篇 |
2001年 | 198篇 |
2000年 | 149篇 |
1999年 | 116篇 |
1998年 | 87篇 |
1997年 | 82篇 |
1996年 | 84篇 |
1995年 | 69篇 |
1994年 | 57篇 |
1993年 | 27篇 |
1992年 | 51篇 |
1991年 | 31篇 |
1990年 | 37篇 |
1989年 | 22篇 |
1988年 | 25篇 |
1987年 | 23篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
101.
J. -M. Chong Y. Shiozawa Y. Hayashi N. Funata T. Takizawa M. Koike M. Fukayama 《Virchows Archiv : an international journal of pathology》1996,428(4-5):261-266
We report a case of pancreatic acinar cell carcinoma which contained a large number of pleomorphic inclusions with fibrillary internal structures and mature zymogen granules. To clarify the significance of fibrillary inclusions in the differentiation of acinar cells of the pancreas, we further investigated fetal pancreases (gestational weeks 16, 17, 19, 20 and 28). We found two types of inclusions: type A, corresponding to fibrillary inclusion of neoplastic acinar cells, was observed only in a 19-week fetus; type B showed a homogeneous density similar to that of zymogen granules. Type B was observed in all the fetuses after the 17th gestational week. Although the type A inclusion might be generated throught a different mechanism than the type B inclusion, the appearance of a large number of fibrillary inclusions in neoplastic acinar cells may represent a transient form of zymogen granule. 相似文献
102.
103.
由于人体组织中存在血液对流传热和代谢产热,当皮肤表面绝热后,皮肤表面的温度将上升,体表温升值是人体组织中血液灌注率和动脉血温度的函数,根据实际测量的体表温升与时间的关系就可以测出活体组织的血液灌注率和动脉血温度。根据一维Pennes生物传热方程,推导出了体表绝热后人体组织中及皮肤表面温度分布的解析解,并对人体组织中的血液灌注率及动脉血温度进行了实验测量。由于测量过程中利用的只是皮肤表面的温度信息,无须引入外加热源,对人体组织完全不会造成损伤,亦避免了干扰人体组织的正常生理状态,整个测量系统也比较简单。 相似文献
104.
We comment on the target article by Weingardt (this issue), which discusses recent advances in instructional design and technology (IDT) and their implications for dissemination of evidence-based practices. These arguments are extended to the topic of psychological intervention design, and possibilities for new intervention structures are briefly explored. Finally, comments are offered on maintaining a careful balance between technological and social processes in the effort to promote the dissemination of innovative and evidence-based psychological procedures. 相似文献
105.
M. Grattarola M. Bove S. Martinoia G. Massobrio 《Medical & biological engineering & computing》1995,33(4):533-536
The paper deals with computer simulations of ‘silicon neurons’, which are assemblies of CMOS circuits that generate the equivalents
of the ionic currents and of the action potentials of real (biological) neurons. The circuit simulation program SPICE is used
to simulate the generation of action potentials by a silicon neuron. Moreover, the equivalent circuits of silicon synapses
are described and the behaviours of simple two- and three-neuron networks are analysed. Implications for the areas of neurobiology
and formal neural networks are briefly considered. 相似文献
106.
Safety of cryopreservation straws for human gametes or embryos: a study with human immunodeficiency virus-1 under cryopreservation conditions 总被引:3,自引:0,他引:3
107.
Salim R Ben-Shlomo I Colodner R Keness Y Shalev E 《Human reproduction (Oxford, England)》2002,17(2):337-340
BACKGROUND: Overgrowth of bacteria in the birth canal is associated with an increased risk of late miscarriage, preterm labour, post-partum endometritis and low birthweight. Conception rates in assisted reproduction treatments (ART) remain frustratingly low. We examined whether the nature of bacterial flora, found in the uterine cervical canal at embryo transfer, is associated with the rate of conception in ART. METHODS: We sampled for bacteriological culture the cervical canal of 204 patients who underwent embryo transfer. Of these, 139 (68%) were of fresh embryos, following recent vaginal oocyte retrieval and prophylactic antibiotic therapy, and 65 (32%) of frozen-thawed embryos, without any vaginal intervention in the preceding days. Bacteriological work-up included identification, colony count and antibiotic susceptibility profile. Conception was correlated with bacterial type and colony count. RESULTS: In 75 patients (36.8%) sterile cervical cultures or lactobacillus were recorded. Of these 75 patients, 23 (30.7%) conceived, whereas among the 129 in whom any pathogenic micro-organism was recovered only 21 (16.3%) conceived (P = 0.002). No difference in colonization was found between women who underwent frozen-thawed versus fresh embryo transfer (57 and 67% respectively). Any Gram-negative colonization was associated with no conception. All Gram-positive, and 90% of the Gram-negative bacteria, were sensitive to augmentin. CONCLUSIONS: Failure to conceive in ART is significantly associated with bacterial colonization of the uterine cervix. 相似文献
108.
目的探讨重点理工科学校大一新生焦虑状况及相关因素,为进行针对性的干预提供依据。方法以广东某重点理工高校2007级的大一学生为研究对象,采用自行设计一般项目调查表、状态-特质焦虑量表(STAI)、匹兹堡睡眠质量指数量表(PSQI)、应付方式问卷进行测评。结果测查学生不论男女状态焦虑、特质焦虑分均显著高于地方常模;19.29%的学生睡眠质量较差;高状态焦虑组和高特质焦虑组解决问题、求助应付因子分均显著低于低状态焦虑组和低特质焦虑组,而自责、幻想、退避应付因子分则显著高于低状态焦虑组和低特质焦虑组;多元逐步回归分析说明,学生如常采用解决问题应付方式,在一定程度上可避免焦虑的产生,而睡眠质量差、采用自责应对方式则可加重焦虑水平。结论采取有效的认知应对策略其意义是使学生改变应激源,以使其变得威胁较小或变成挑战,把情绪基调训练成兴奋、期待和征服。 相似文献
109.
Children born into allergic families, with two allergic parents, are at high risk of developing allergy within the first 5 years of life. In order to observe possible external factors in the sensitization process, a prospective study of 13 such children was done, in which serial clinical and immunologic observations were made at 3- to 6-month intervals over a period of 1 to 4 yr. Eleven of these children are now clinically allergic; 5 have asthma. Immunologic evidence for allergic sensitization was observed in these 11 children by RAST, antigen-induced leukocyte histamine release, lymphoblastogenesis, and rise in serum IgE. Upper respiratory infections (URI) occurred in these 11 allergic children 1 to 2 months prior to the onset of allergic sensitization. In 10 of these 11 URI children, complement-fixing antibodies to viruses (parainfluenza, RSV, CMV) increased in the same blood samples in which immunologic allergic sensitization was first evidenced. This coincidence suggests that certain viruses may contribute to the allergic sensitization process. 相似文献
110.
目的:分离、培养和鉴定人骨髓间充质干细胞(Mesenchymal stem cells,MSCs),应用改良的Transwell侵袭小室技术,探讨血管内皮生长因子(VEGF)及内皮细胞条件诱导液对其体外诱导分化中的作用。方法:采用Percoll(1.073g/ml)分离液分离骨髓单个核细胞,体外培养MSCs,流式细胞术分析鉴定MSCs的纯度,Transwell侵袭小室技术结合LSCM,实时监测MSCs在Matrigel与VEGF/内皮细胞条件诱导液构成的内皮细胞生长微环境中的运动迁移情况。结果:经Percoll分离、体外培养扩增的MSCs,细胞纯度可达95%左右;VEGF组迁移的深度虽高于对照组(P〈0.05),但迁移至聚碳酸脂膜下的细胞与对照组相比,并无统计学意义(P〉0.05)。内皮细胞条件诱导液促进MSCs的迁移,在Matrigel内迁移的深度及迁移至聚碳酸脂膜下的细胞均明显多于对照组(P〈0.05)。结论:共聚焦激光扫描显微术与Transwell侵袭小室技术的结合,能够从时间和空间上对后者进行观察,使该实验得到改良;利用内皮细胞条件诱导液与Matrigel模拟体外内皮细胞生长的微环境,并从空间上观测了MSCs穿越人工基底膜的情况,为MSCs向内皮细胞体外诱导开辟了新的思路。 相似文献