全文获取类型
收费全文 | 45247篇 |
免费 | 4403篇 |
国内免费 | 3659篇 |
专业分类
耳鼻咽喉 | 386篇 |
儿科学 | 479篇 |
妇产科学 | 619篇 |
基础医学 | 5434篇 |
口腔科学 | 1000篇 |
临床医学 | 5953篇 |
内科学 | 6760篇 |
皮肤病学 | 513篇 |
神经病学 | 2362篇 |
特种医学 | 1729篇 |
外国民族医学 | 20篇 |
外科学 | 4668篇 |
综合类 | 7739篇 |
现状与发展 | 15篇 |
一般理论 | 6篇 |
预防医学 | 3059篇 |
眼科学 | 1201篇 |
药学 | 4657篇 |
28篇 | |
中国医学 | 2803篇 |
肿瘤学 | 3878篇 |
出版年
2024年 | 151篇 |
2023年 | 685篇 |
2022年 | 1817篇 |
2021年 | 2260篇 |
2020年 | 1733篇 |
2019年 | 1457篇 |
2018年 | 1588篇 |
2017年 | 1459篇 |
2016年 | 1347篇 |
2015年 | 2002篇 |
2014年 | 2543篇 |
2013年 | 2183篇 |
2012年 | 3186篇 |
2011年 | 3485篇 |
2010年 | 2109篇 |
2009年 | 1743篇 |
2008年 | 2228篇 |
2007年 | 2313篇 |
2006年 | 2264篇 |
2005年 | 2064篇 |
2004年 | 1698篇 |
2003年 | 1815篇 |
2002年 | 1626篇 |
2001年 | 1390篇 |
2000年 | 1227篇 |
1999年 | 1309篇 |
1998年 | 879篇 |
1997年 | 808篇 |
1996年 | 639篇 |
1995年 | 582篇 |
1994年 | 510篇 |
1993年 | 265篇 |
1992年 | 355篇 |
1991年 | 292篇 |
1990年 | 271篇 |
1989年 | 221篇 |
1988年 | 214篇 |
1987年 | 175篇 |
1986年 | 149篇 |
1985年 | 93篇 |
1984年 | 78篇 |
1983年 | 33篇 |
1982年 | 18篇 |
1981年 | 16篇 |
1980年 | 14篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1969年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Yanhong Li Shuanke Wang Yayi Xi Jing Wang Wenjie Pan Yingbin Shi Mige Wang 《中国神经再生研究》2007,2(8):471-474
BACKGROUND: At present, there is still lack of effective drugs for chronic spinal cord injury, whereas it is found recently that estrogen has a neuroprotective effect on brain and spinal cord injuries.
OBJECTIVE: To observe the effect of estrogen on the apoptosis of nerve cells after gradual chronic spinal cord injury in ovariectomized rats.
DESIGN: A randomized controlled animal trial.
SETTING: Institute of Orthopaedics, the Second Hospital of Lanzhou University.
MATERIALS: Sixty-five female Wistar rats of common degree, weighing 220–250 g, were provided by the experimental animal center of Lanzhou University. The rats were randomly divided into sham-operated group (n =5), estrogen-treated group (n =30) and saline control group (n =30), and the latter two groups were observed at 1, 3, 7, 14, 28 and 60 days respectively, and 5 rats for each time point.
METHODS: All the rats were treated with bilateral oophorectomy 2 weeks before the experiment. T10 vertebral lamina was revolved into using plastic screw. The spinal canal impingement was not induced initially. After that, the original incision was opened to expose the screw every 7–10 days.
MAIN OUTCOME MEASURES: The apoptosis and Caspase-3 positive cells in the damaged spinal cord were detected using terminal deoxynucleotidal transferase-mediated dUTP-biotin nick end labeling (TUNEL) method and Caspase-3 immunohistochemical staining at 1, 3, 7, 14, 28 and 60 days after chronic spinal cord injury respectively.
RESULTS: Totally 65 rats were used, and the deleted ones during the experiment were supplemented by others. Changes of Caspase-3 expression after spinal cord injury: In the sham-operated group, only a small amount of Caspase-3 proteins were observed in the rat spinal cord, mainly located in motor neurons of spinal cord anterior horn. In the estrogen-treated group and saline control group, positive cells expressed occasionally at 1 day postoperatively, began to increase obviously at 7 days after injury, strongly expressed at 14 and 28 days, but decreased at 60 days, mainly located in the neurons of spinal cord gray matter anterior horn, and they expressed fewer in the motor neurons and white matter of ventral horn, and there were obvious differences between the estrogen-treated group and saline control group at 7, 14, 28 and 60 days (P < 0.05).
CONCLUSION: Estrogen can reduce the apoptosis of nerve cells and promote the recovery of neurological function following gradual chronic spinal cord injury. 相似文献
122.
急进性后极部早产儿视网膜病变的临床进程及疗效观察 总被引:1,自引:0,他引:1
目的 描述急进性后极部早产儿视网膜病变(AP-ROP)的临床进程及特征,评价视网膜光凝及冷凝对急进性后极部早产儿视网膜病变的治疗效果.方法 前瞻性、非对比性、连续性病例.2006年1月至2008年6月经检查确诊为急进性后极部ROP的患儿8例16只眼.确诊后24h内行间接眼底镜下行视网膜光凝治疗联合或不联合直视下冷凝治疗.结果 急进性后极部早产儿视网膜病变以病变大部分位于后极部1区,所有象限视网膜血管扩张迂曲,病程进展快,若不及时治疗,迅速发生视网膜漏斗状全脱离为临床特征.本组8例16只眼视网膜光凝和(或)冷凝治疗后,9只眼病变完全退化或控制,占56.2%.7只眼病情未能控制,最终发展为4b至5期视网膜病变.结论 AP-ROP进展快,预后不良,部分患儿虽经严密观察和治疗,病情仍进展.视网膜光凝和(或)冷凝治疗能控制大部分AP-ROP患儿视网膜病变的发展,挽救患儿视功能.临床上需要加强观察和随访,早发现、早诊断、早治疗是减低该病致盲率的惟一方法. 相似文献
123.
目的初步探讨阻塞性黄疸早期门静脉高压的机制。方法将大鼠分为胆管结扎组(B)与假手术组(A),分别于术后3、7、14d比较两组的游离门静脉压力(FPP)、血浆和肝组织内皮素(ET)浓度。结果胆总管结扎7d后门静脉压力显著高于对照组;胆总管结扎后各时段ET水平均显著高于对照组;门静脉压力与血浆ET、肝组织ET呈正相关。结论阻塞性黄疸早期即有门静脉压力的升高,它可能是体内ET水平升高致肝窦阻力增加的结果。 相似文献
124.
踝关节侧副韧带损伤的超声表现 总被引:6,自引:0,他引:6
目的 分析踝关节侧副韧带损伤的超声图像特征并评价其诊断价值。方法 采用7~13MHz线阵探头探查136例临床怀疑踝关节侧副韧带损伤患者,观察胫舟、胫距前、胫跟、距腓前、跟腓、胫距后、距腓后韧带,共计952条韧带,其中,51例的超声结果与手术比较。结果 46例侧副韧带完全及部分撕裂伤的超声诊断与手术结果符合。侧副韧带挫伤以肿胀为主,部分撕裂伤超声表现为韧带局部连续性中断(跟腓韧带)和不规则低-无回声区内见丝状结构相连,完全撕裂伤超声表现为韧带连续性中断,断端挛缩(跟腓韧带)和不规则低-无回声区贯穿整条韧带,无明显断端挛缩征。结论 高频超声对踝关节侧副韧带损伤的诊断无创、较准确、廉价,具有较高的临床应用价值。 相似文献
125.
OBJECTIVE: To study the expression of neuron-specific enolase (NSE) and olfactory marker protein (OMP) in the developing olfactory mucosa of human fetuses. METHOD: The expression of NSE and OMP in the olfactory mucosa of 6 human fetuses (12, 16, 20, 24, 28 and 34 weeks) was studied using the technique of immunohistochemistry. RESULTS: NSE immunological positive reactions were seen in all 6 fetal mucosa from gestational 12 (G12) to G34, with plenty of positive-stained dual-pole neuron cells. At G12, the positive cells aligned tightly, the cell bodies were localized in the lower portion of olfactory epithelium and the positive-stained area occupied upper 2/3 of fetal nasal mucosa. With the development, the positive cells gradually became multilayer, but the density and the relative area of positive-cells reduced. At G34, the positive cells were located only in upper 1/3 of nasal mucosa. OMP-positive reactions were localized in a few dual-pole neurons at G12, the number was much less than NSE-positive cells in the same fetus. With the development, the OMP-positive cells gradually increased with most of the cell bodies located in the upper portion of epithelium, but number still relatively less than the NSE-positive cells at the same age. CONCLUSION: At G12, there were lots of olfactory neuron in the olfactory mucosa and only a few olfactory neurons had became mature. With the development, the olfactory epithelial area reduced but the number of mature olfactory neurons increased. At the last trimester, fetal olfactory sensor was almost matured. 相似文献
126.
Weijiang Zhao Fang Yuan Guilin Li Zhongfang Shi Yun Cui Yazhuo Zhang Zhongcheng Wang 《中国神经再生研究》2007,2(5):276-280
BACKGROUND: During formation of prolactin neoplasia, how cells and its structure in adenohypophysis affect prolactin cells should be further studied. Intermediate lobe can be regarded as a driving region to release prolactin (PRL) and may promote formation of prolactin neoplasia in pituitary anterior lobe.
OBJECTIVE: To observe the effect of diethylstilbestrol (DES) on the expressions of μ and m-calpains in pituitary intermediate lobe of female Wistar rats.
DESIGN: Observational contrast animal study.
SETTING: Beijing Neurosurgical Institute.
MATERIALS: A total of 21 female Wistar rats, 3 weeks old weighing 70–80 g were housed with free access to tap water and standard pellet food. They were kept in a CL-grade condition, at (24±1)℃ and a humidity of (55±5)%, and with a 12 hours day-night cycle. Caprine anti-μ- and m-calpains antibodies were provided by Santa Cruz Biotechnology, CA, USA; rabbit-anti-PRL antibodies by Dako, Denmark; rabbit-anti-ACTH antibody by Boster Company, Wuhan.
METHODS: The experiment was carried out in Pathophysiological Department and Animal Laboratory, Beijing Neurosurgical Institute from August 2006 to January 2007. ① Rats were randomly divided into groups with 7 in each group, including vehicle control group, in which rats were injected intraperitoneally with sun-flower seed oil (1 mL/kg, twice a week) for 16 weeks; DES group, where animals were administered with DES (5 mg/kg, twice a week) for 16 weeks; DES + vehicle control group, in which DES was administered for 12 weeks at the same dose with those in DES group, and then was discontinued and replaced by sun-flower seed oil (1 mL/kg, twice a week) for the following 4 weeks. ② At 16 weeks later, pituitary tissue was dealt with HE staining and PRL immunohistochemical examination to observe evoke of tumor; meanwhile, immunohistochemical examination was used to observe expression of PRL of pituitary anterior lobe, expressions of μ- and m-calpains of pituitary intermediate lobe and distribution of adrenocorticotropin.
MAIN OUTCOME MEASURES: ① Expression of PRL of pituitary anterior lobe, expressions of μ- and m-calpains of pituitary intermediate lobe and distribution of adrenocorticotropin. ② Morphological observation of pituitary tissue.
RESULTS: All 21 rats were involved in the final analysis. ① Results of immunohistochemical examination: Morphological changes of neoplasia in DES group were strongly positive to PRL, and this suggested that formation of prolactin adenoma was observed in pituitary tissue. As compared with vehicle control group, expression of adrenoeorticotropic hormone (ACTH) was increased in both DES group and DES + vehicle control group. In addition, expressions of μ- and m-calpains in pituitary intermediate lobe were higher in DES group than that in vehicle control group. Otherwise, expressions of m-calpains in pituitary intermediate lobe was decreased in DES + vehicle control group, but expression of μ-calpains was still increased. ② Morphological observation of pituitary tissue: Gland tubes were orderly arranged in rats in vehicle control group. Anterior pituitary gland in rats of DES group demonstrated an apparent disappearance of gland tubes and a relatively large-scaled vasculature formation, namely the vascular lake lined by tightly arranged endothelial cells. Local integrated tumor cell arrangements were also detected. In addition, the border between the IL and the anterior lobe was locally blurred. The definite tumor-like changes in pituitary tissues were confirmed in 6 of 7 female Wistar rats in DES group, and one spontaneous occurrence of tumor formation was found in vehicle control group. In DES + vehicle control group, DES withdrawal led to the subtile emergence of gland tube cavity, although tumor-like cells still existed in 4 of 7 rats, suggesting occurrence of the tumor regression due to the withdrawal of DES.
CONCLUSION: A long-term application of DES can enhance the expressions of ubiquitours neutral cysteine protease in pituitary intermediate lobe and this suggests that both of them play a key role in release of hormone and formation of prolactin neoplasia through directly promoting PRL expression and release of neighboring pituitary intermediate lobe. 相似文献
127.
Chenhui Shi Wenjun Gui Jie Chen Guonian Zhu 《Bulletin of environmental contamination and toxicology》2010,84(2):236-239
Oxadiargyl is a commonly used herbicide in China. We developed a simple, fast, and high-throughput method employing gas chromatography with electron capture detector to determine oxadiargyl residues in food samples (rice, straws) and environmental samples (soil, water). Samples were prepared by a modified QuEChERS procedure. In this method, acetonitrile was used as the extracting solvent. The purifying step was omitted when the chromatographic conditions were optimized. Recoveries ranged from 82.9 to 112.0% for oxadiargyl in all samples, with relative standard deviation values lower than 6.2% at 0.01 mg/kg fortified concentration level. 相似文献
128.
129.
动态观察胆总管急性完全性梗阻并感染、继发休克兔的血浆血栓素(TXA_2)和前列环素(PGI_2)的稳定代谢产物 TXB_2和6-keto-PGF_(1α)含量及血小板聚集率的变化。结果,血浆 TXB_2呈进行性升高,20h 后(休克时)呈下降趋势,血浆6-keto-PGF_(1α)6h 升高,随后回降;血小板聚集率呈进行性下降。提示血栓素和前列环素、血小板聚集率的变化在重症急性胆管炎、胆源性感染性休克发病过程中起重要病理生理作用,与病情和预后转归有重要联系。 相似文献
130.
本文对44例牙源性脓肿(尖周脓肿24例,牙周脓肿12例,冠周脓肿8例)脓液标本中的产黑色素类杆菌群菌株进行分离、培养、鉴定。其中38例存在产黑菌群,以中间型类杆菌阳性率最高。牙龈类杆菌在牙周脓肿中检出率最高。24例尖周脓肿可分离出6株牙髓类杆菌而其它两种牙源性脓肿则无牙髓类杆菌,推测该菌与牙髓尖周感染的病理过程有关。 相似文献