首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   482篇
  免费   24篇
  国内免费   10篇
儿科学   13篇
妇产科学   5篇
基础医学   47篇
口腔科学   7篇
临床医学   30篇
内科学   50篇
皮肤病学   6篇
神经病学   42篇
特种医学   24篇
外科学   31篇
综合类   62篇
预防医学   78篇
眼科学   3篇
药学   82篇
中国医学   28篇
肿瘤学   8篇
  2023年   5篇
  2022年   15篇
  2021年   32篇
  2020年   14篇
  2019年   12篇
  2018年   9篇
  2017年   12篇
  2016年   12篇
  2015年   31篇
  2014年   42篇
  2013年   37篇
  2012年   25篇
  2011年   22篇
  2010年   23篇
  2009年   15篇
  2008年   26篇
  2007年   16篇
  2006年   18篇
  2005年   15篇
  2004年   13篇
  2003年   18篇
  2002年   9篇
  2001年   6篇
  2000年   4篇
  1999年   5篇
  1998年   7篇
  1997年   6篇
  1996年   5篇
  1995年   5篇
  1994年   4篇
  1993年   7篇
  1992年   6篇
  1991年   3篇
  1990年   2篇
  1989年   4篇
  1988年   2篇
  1987年   7篇
  1986年   1篇
  1985年   6篇
  1984年   4篇
  1983年   3篇
  1982年   1篇
  1981年   5篇
  1980年   1篇
  1970年   1篇
排序方式: 共有516条查询结果,搜索用时 31 毫秒
91.
本文对玉米花粉山楂口服液进行了四项致突变试验,结果表明该受试物Ames 试验和小鼠骨髓嗜多染红细胞微核试验为阴性、人体外周血淋巴细胞体外培养染色体畸变试验和小鼠精子畸形试验均未引起畸变率升高。试验结构表明,OCPHL 无致突变性。  相似文献   
92.
This study was conducted to evaluate the effect of lactic acid bacteria (LAB) on fermentation quality, mycotoxin concentrations, and microbial communities of whole-crop corn silages infested with mycotoxigenic fungi. Cultured spores (106 cfu/mL) of mycotoxigenic Aspergillus flavus and Fusarium graminearum were sprayed (5 mL) on corn forage on 27 July and 10 August 2018. On 21 August 2018, sprayed (FI; 3 plots) and unsprayed (NFI; 3 plots) corn forage were harvested at the 1/2 kernel milk line stage, followed by chopping and ensiling without inoculants (CON), or with Lactobacillus buchneri (LB, 1 × 106 cfu/g FW), Lactobacillus plantarum (LT, 1 × 106 cfu/g FW), or L. buchneri + L. plantarum (BT: both L. buchneri and L. plantarum applied at 0.5 × 106 cfu/g FW). After 90 d of ensiling, FI silages had a higher (p < 0.05) pH value and higher acetic acid (ACA), ethanol, and ammonia nitrogen (ammonia N) concentrations, but lower (p < 0.05) lactic acid (LA) concentrations than NFI silage. The inoculants decreased pH and increased LA concentration and LA/ACA compared with CON. The aflatoxin B1 (AFB1) was only detected in FI fresh corn and silages; ensiling decreased (p < 0.05) AFB1 concentration compared with fresh corn, and LB and BT decreased AFB1 concentration compared with CON. The zearalenone (ZEN), deoxynivalenol (DON), and fumonisin B1 (FB1) concentrations were similar (p < 0.05) for NFI silages, while ZEN concentration in BT was the lowest (p < 0.05) among all FI silages; DON and FB1 concentrations in LB, LT, and BT silages were significantly lower (p < 0.05) than those of CON in FI silages. The fungal infestation increased the bacterial and fungal diversity of silages compared with NFI silages. The FI silages had a higher relative abundance (RA) of Lactobacillus, Weissella, Wickerhamomyces, Pichia, and Epicoccum than the corresponding NFI silages. The RA of Aspergillus and Fusarium markedly decreased after 90 d of ensiling, and the inoculation expanded this trend irrespective of fungal infestation. The Penicillium in FI silages survived after 90 d of ensiling, while the inoculants decreased the RA of Penicillium. Inoculants mitigate the adverse effects of fungal infestation on corn silage quality by changing the bacterial and fungal communities.  相似文献   
93.

Introduction

Circulating microparticles are reported to play a role in cancer hypercoagulability. The procoagulant properties of microparticles derive from the amount of tissue factor and/or phosphatidylserine that they can expose. The aim of our study is to assess the procoagulant activity, including microparticles’ activity, in the plasma of newly diagnosed cancer patients with a simple assay, easy to implement in the laboratory.

Material and methods

Newly diagnosed cancer patients (n = 31) before the start of anticoagulant or chemotherapy were compared to matched controls. We used a thrombin generation assay in four conditions: 1: addition of 1pM tissue factor and 4 μM procoagulant phospholipids, 2: without any trigger, 3 and 4: addition of tissue factor or procoagulant phospholipids alone respectively.

Results

When we added only phospholipids, so that thrombin generation is dependent upon endogenous tissue factor, the lag time was significantly shorter in cancer patients. When we added only tissue factor, i.e. made the results dependent upon phospholipids, the endogenous thrombin potential, the peak, and the velocity index were significantly higher and the time-to-peak was significantly shorter. This suggests that the plasma of cancer patients contained a higher activity of endogenous phospholipids and/or tissue factor which may be borne by microparticles.

Conclusion

This new simple methodology can demonstrate a procoagulant activity in the plasma of newly diagnosed cancer patients which can be explained by higher procoagulant phospholipids and tissue factor activity and thus, brings potentially useful information that current coagulation tests cannot provide.  相似文献   
94.
目的:优选大孔吸附树脂纯化茶梗中茶多酚的工艺条件,为茶梗二次开发提供参考。方法:采用静态吸附-解吸和动态吸附-解吸试验对9种不同型号树脂进行筛选;以茶多酚含量为指标,采用单因素试验优选大孔树脂纯化茶多酚的工艺参数。结果:LX-18型大孔吸附树脂纯化效果最好;最佳工艺条件为上样液中生药与树脂的质量比1∶1,吸附速度2 mL·min-1,分别用10倍量水、50%乙醇洗脱;茶多酚纯度53.79%。结论:该优选的方法简便可行、纯化效果好,可为茶多酚相关产品的开发提供参考。  相似文献   
95.
The pathological transformation of the skin into a thick and hard callus due to repetitive trauma or friction is commonly known as corn. Although a variety of medical and operative treatment choices have been proposed, an ideal treatment method is yet to be defined. Effectiveness of tangential excision together with topical cantharidin has been evaluated. We used Canthacur-PS as an adjunct to excision in an outpatient setting. Canthacur-PS is a commercially available topical solution that includes 1% cantharidin, 30% salicylic acid and 5% podophyllin. The treatment has been applied to 72 patients. We found that 65 patients (90.3%) had corn on their feet and seven patients (9.7%) on their hands. Thick, hard and hyperkeratotic skin area was scraped with the help of a no. 15 blade. The solution was applied on and around the periphery (up to 1–2 mm) of the lesion with a cotton swab, and kept closed for 5 days with an antibiotic dressing. All the patients had been followed up for at least 1 year and evaluated by clinical examination and patient satisfaction query. One session of treatment succeeded in 57 (79.2%) corn patients. Two sessions in nine corn patients (12.5%), three sessions in five corn patients (6.9%) and four sessions in one patient (1.4%) were needed. Only one recurrence (1.4%) was seen. No scar formation or other side-effects were seen. Our findings show that this treatment method is a simple, minimally invasive and reliable treatment for calluses.  相似文献   
96.
洁净手术室净化空调系统调试   总被引:1,自引:0,他引:1  
洁净手术室净化空调系统施工,历经前期净化空调方案的论证,经济效益和费用的评价,方案批准后的深化设计,实施阶段的安装和中间验收,最后到达系统调试和综合性能检测阶段。为把方案、安装阶段的优势转化为合乎规范要求的工程综合性能检测指标,必须对净化空调系统调试工作进行深入策划,制定可靠的路线图,按图索骥,严格执行调试流程规范,才能取得洁净手术室建设的丰硕成果。  相似文献   
97.
[目的]了解制革工业园区周围粮食的铬污染程度,为粮食铬污染防治策略制定提供背景数据。[方法]采集制革园区周围农田所产粮食(36份)和对照区种植粮食样品(22份),分别检测其铬含量,采用《食品中污染物限量》(GB2762-2005)计算其超标率,采用单因子污染指数法评价粮食中铬污染程度。[结果]制革工业园区周围农田所产粮食的铬含量为0.74mg/kg,而对照区为0.18mg/kg,差异有统计学意义(P〈O.05);该工业园区周围种植粮食铬超标率为16.66%,明显高于对照区(0%)(P〈0.05);小麦和玉米单因子污染指数平均值均小于l。[结论]该制革工业园区周围部分种植点粮食受到了铬污染,可能会对暴露人群构成危害。  相似文献   
98.
Objective: To examine the pathological findings that occurred in the lens and cornea and biochemical findings in the lens of rats fed with corn syrup and the protective effects of alpha lipoic acid (ALA).

Materials and methods: Twenty-four rats were randomly divided into three groups. Group I served as the control group. Group II was used as the study group; the rats were treated with 30% corn sugar solution for 10 weeks. Group III was the treatment group. Corn syrup was given by the oral route to the rats during the study, and ALA (100?mg/kg) was added to the treatment 4 weeks after the study began. At the end of the experiment, central corneal thickness (CCT) was measured in all rats with an ultrasonic pachymeter. Then the right eyes of the rats were enucleated for histopathological examination of the cornea and lens. The left lenses were homogenized for biochemical analyses.

Results: The lenses of the rats treated with corn syrup revealed severe damage; many lens fibers appeared swollen and ruptured with large vacuoles near the lens epithelium. In addition, malondialdehyde (MDA) levels, a parameter of oxidative stress, increased but not significantly in Group II; however. ALA treatment decreased MDA levels significantly. Antioxidant enzyme and catalase (CAT) activities were significantly decreased in Group II, and ALA treatment increased these activities; however, the increase was not significant. Changes were observed in the cornea such as epithelial alterations, subepithelial vacuolizations, collagen fibers loss in the stromal layer, interruptions in the subepithelial basement membrane and central corneal thickening.

Conclusions: Corn syrup can cause severe damage in rat lenses and corneas. However, ALA ameliorates the effect of corn syrup-related lesions on the cornea and lens.  相似文献   
99.
目的 分析垂体强化磁共振成像(MRI)在垂体柄阻断综合征中的诊断价值及对垂体- 靶腺功能 损伤的评估意义。方法 选取该院86 例垂体柄阻断综合征者为病例组,另选取50 例健康儿童和青少年为对照 组。根据病例组垂体MRI 表现,其中完全性垂体柄阻断者为A 组,部分性垂体柄阻断者为B 组。比较A 组、 B 组与对照组相关激素参数的水平,并分析MRI 表现与垂体- 靶腺功能损伤的关系。结果 病例组86 例患 者中垂体后叶正常4 例(4.65%),体积变小16 例(18.60%),发生异位56 例(65.12%),缺失10 例(11.63%)。 A 组、B 组睾酮(T)、雌二醇(E2)、促黄体生成素(LH)等性激素水平较对照组均降低(P <0.05),而A 组 T 水平较B 组降低(P <0.05),而A、B 两组其他性激素水平的比较,差异无统计学意义(P >0.05)。A 组皮质 醇(COR)、促肾上腺皮质激素(ACTH)、游离甲状腺素(FT4)、促甲状腺激素(TSH)等激素的水平较 对照组、B 组均降低(P <0.05);B 组COR 和FT4 的水平较对照组均降低(P <0.05),而其他激素水平的比较, 差异无统计学意义(P >0.05)。A 组因垂体激素缺乏引起继发性肾上腺功能减退、甲状腺功能减退和中枢性 尿崩症的发生率较B 组升高(χ2=10.24、7.35 及9.35,均P <0.01)。结论 垂体强化MRI 能够有效诊断垂体 柄阻断综合征者垂体-靶腺功能损伤的状况,其在评估垂体柄阻断综合征垂体功能中具有较高的诊断价值。  相似文献   
100.
Body stalk anomaly (BSA) is a sporadic polymalformative syndrome incompatible with extrauterine life. In utero detection of BSA by two-dimensional and three-dimensional ultrasonography and magnetic resonance imaging has been well documented. We herein describe a case of body stalk anomaly diagnosed at autopsy. The fetus had a large anterior midline abdominal wall defect with eventration of the visceral organs into the amnio-peritoneal sac and a completely absent umbilical cord. The associated anomalies included club foot, absent diaphragm, genitourinary, and gastrointestinal defects. The observed congenital anomalies supported the theory of embryonic dysgenesis as the etiologic factor. One of the major objectives in the performance of fetal autopsy is to be able to detect abnormalities that can have implications in future pregnancies. Despite the negligible familial recurrence rate of the broad spectrum of anomalies associated with this abdominal wall defect, the present case of fetal autopsy indeed delights to serve the living.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号