全文获取类型
收费全文 | 56475篇 |
免费 | 5405篇 |
国内免费 | 3857篇 |
专业分类
耳鼻咽喉 | 469篇 |
儿科学 | 1074篇 |
妇产科学 | 603篇 |
基础医学 | 5388篇 |
口腔科学 | 903篇 |
临床医学 | 7765篇 |
内科学 | 7287篇 |
皮肤病学 | 619篇 |
神经病学 | 2354篇 |
特种医学 | 1792篇 |
外国民族医学 | 26篇 |
外科学 | 4533篇 |
综合类 | 11624篇 |
现状与发展 | 6篇 |
一般理论 | 7篇 |
预防医学 | 4930篇 |
眼科学 | 1269篇 |
药学 | 7124篇 |
52篇 | |
中国医学 | 4125篇 |
肿瘤学 | 3787篇 |
出版年
2024年 | 210篇 |
2023年 | 755篇 |
2022年 | 2165篇 |
2021年 | 2691篇 |
2020年 | 2215篇 |
2019年 | 1646篇 |
2018年 | 1764篇 |
2017年 | 1827篇 |
2016年 | 1661篇 |
2015年 | 2657篇 |
2014年 | 3300篇 |
2013年 | 3192篇 |
2012年 | 4845篇 |
2011年 | 5285篇 |
2010年 | 3881篇 |
2009年 | 3182篇 |
2008年 | 3609篇 |
2007年 | 3363篇 |
2006年 | 3124篇 |
2005年 | 2782篇 |
2004年 | 1927篇 |
2003年 | 1688篇 |
2002年 | 1340篇 |
2001年 | 1052篇 |
2000年 | 936篇 |
1999年 | 940篇 |
1998年 | 534篇 |
1997年 | 567篇 |
1996年 | 386篇 |
1995年 | 332篇 |
1994年 | 268篇 |
1993年 | 189篇 |
1992年 | 226篇 |
1991年 | 187篇 |
1990年 | 155篇 |
1989年 | 149篇 |
1988年 | 112篇 |
1987年 | 137篇 |
1986年 | 90篇 |
1985年 | 75篇 |
1984年 | 59篇 |
1983年 | 32篇 |
1982年 | 25篇 |
1981年 | 32篇 |
1980年 | 23篇 |
1979年 | 19篇 |
1978年 | 25篇 |
1977年 | 16篇 |
1976年 | 12篇 |
1974年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
降调节对卵子质量的影响 总被引:2,自引:0,他引:2
近10余年来,在体外受精一胚胎移植(IVF-ET)周期中应用促性腺激素释放激素激动剂(GnRH-a)进行控制性卵巢刺激(COS)已成为普遍采用的方法,其主要原因是GnRH-a可以促进卵巢内多个卵泡同步发育和成熟,抑制内源性黄体生成素(LH)峰,阻遏卵泡过早黄素化及卵子早熟。由于GnRH-a在IVF-ET进行降调节COS中的应用不同,可将COS方案分为长方案和短方案。[第一段] 相似文献
102.
103.
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
104.
乙型肝炎治疗研究进展 总被引:1,自引:1,他引:0
乙性肝炎病毒感染所导致的慢性肝炎是我国的一个大问题,给患者及社会带来了很大负担。慢性乙型肝炎现行治疗主要依靠干扰素、核苷类似物等,其存在高耐药、低耐受以及不良反应等问题。新的、更为安全有效的治疗药物及方法亟待发展。最近,科学家们发现人体内的TRIM22分子对抑制乙肝病毒的复制起到重要作用,为乙肝的治疗及有效药物的研发开辟了新的道路。 相似文献
105.
Objective
To observe and evaluate the value of utilizing selective internal iliac artery infusion and selective internal iliac artery embolization for the treatment of unremitting gross hematuria of stage T4 bladder carcinoma. 相似文献106.
冠心病指南中有关心电图的解读 总被引:2,自引:1,他引:1
有关冠心病的国际指南主要有5个:①ACC/AHA处理ST段抬高型心肌梗死指南(1999年第1版,2004年修改);②ACC/AHA处理不稳定型心绞痛和非ST段抬高型心肌梗死指南(2000年第1版,2002年第2版,2007年再修改);③ACC/AHA的处理慢性稳定型心绞痛指南(1999年第1版,2002年修改); 相似文献
107.
Summary Based on the gate-related receptor hypothesis, an analysis of kinetics of AN-132, a new antiarrhythmic agent, blockade of
cardiac sodium channels and the gate-related receptor which is bound by the drug was performed by computer simulation. Model-predicted
apparent rates of onset of AN-132 (30 μmol/L) blocking were 0.051, 0.038, and 0.034 AF−1 at stimulation frequencies of 1.0, 2.0 and 3.0 Hz, respectively. The time constant of recovery from block by AN-132 at resting
potential -90 mV was 39.5 s. These findings are in agreement with those experimental data documented. The analysis of gate-related
receptor shows that AN-132 binds the inactivation gate-related receptor, and the binding and unbinding are modulated by the
inactivation process. 相似文献
108.
吸附澄清法在中药水提液澄清中的应用研究 总被引:30,自引:1,他引:29
采用吸附澄清法使中药水提液澄清,从工艺稳定性,成分分析,药效学实验及效益分析四方面分析了两种工艺,吸附澄清法同水提醇沉法相比,能更有效地保留中药总固体物含量及有效成分,提高制剂成品的内在质量;成品稳定性好;成本低;生产周期短;劳动强度低,可望产生良好的社会经济效益。 相似文献
109.
The antinociceptive effects of morphine (5 μg) microinjected into the ventrolateral periaqueductal gray were determined using both the tail flick and the foot withdrawal responses to noxious radiant heating in lightly anesthetized rats. Intrathecal injection of appropriate antagonists was used to determine whether the antinociceptive effects of morphine were mediated byα2-noradrenergic, serotonergic, opioid, or cholinergic muscarinic receptors. The increase in the foot withdrawal response latency produced by microinjection of morphine in the ventrolateral periaqueductal gray was reversed by intrathecal injection of the cholinergic muscarinic receptor antagonist atropine, but was not affected by the a2-adrenoceptor antagonist yohimbine, the serotonergic receptor antagonist methysergide, or the opioid receptor antagonist naloxone. In contrast, the increase in the tail flick response latency produced by morphine was reduced by either yohimbine, methysergide or atropine. These results indicate that microinjection of morphine in the ventrolateral periaqueductal gray inhibits nociceptive responses to noxious heating of the tail by activating descending neuronal systems that are different from those that inhibit the nociceptive responses to noxious heating of the feet. More specifically, serotonergic, muscarinic cholinergic andα2-noradrenergic receptors appear to mediate the antinociception produced by morphine using the tail flick test. In contrast, muscarinic cholinergic, but not monoamine receptors appear to mediate the antinociceptive effects of morphine using the foot withdrawal response. 相似文献
110.
To compare the characteristics of carboxyfluorescein (CF) and calcein (Calc) with those of sodium fluorescein (Naf), the only fluorescent dye currently in clinical use, we performed angiography in rabbits and primates using these three dyes. The circulation decay time of all dyes was longer in primates than in rabbits. In primates, CF and Calc had longer decay times than Naf. Calc produced the greatest contrast between the choroidal and retinal vasculature. Tissue staining and dye leakage into the vitreous immediately after retinal photocoagulation were minimal with Calc, moderate with CF, and marked with Naf. The limited leakage and longer circulation time of Calc may permit simultaneous angiography and photocoagulation therapy without obscuring the fundus view with leaking dye from the photocoagulated structure. 相似文献