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   2542篇
  免费   138篇
  国内免费   28篇
耳鼻咽喉   28篇
儿科学   36篇
妇产科学   57篇
基础医学   301篇
口腔科学   27篇
临床医学   185篇
内科学   525篇
皮肤病学   11篇
神经病学   414篇
特种医学   86篇
外科学   347篇
综合类   6篇
预防医学   78篇
眼科学   19篇
药学   217篇
中国医学   39篇
肿瘤学   332篇
  2023年   18篇
  2022年   35篇
  2021年   45篇
  2020年   19篇
  2019年   29篇
  2018年   40篇
  2017年   28篇
  2016年   42篇
  2015年   31篇
  2014年   47篇
  2013年   71篇
  2012年   104篇
  2011年   114篇
  2010年   65篇
  2009年   52篇
  2008年   81篇
  2007年   126篇
  2006年   111篇
  2005年   139篇
  2004年   137篇
  2003年   127篇
  2002年   126篇
  2001年   114篇
  2000年   106篇
  1999年   87篇
  1998年   42篇
  1997年   32篇
  1996年   31篇
  1995年   22篇
  1994年   18篇
  1993年   17篇
  1992年   47篇
  1991年   63篇
  1990年   57篇
  1989年   54篇
  1988年   53篇
  1987年   49篇
  1986年   55篇
  1985年   47篇
  1984年   41篇
  1983年   34篇
  1982年   9篇
  1981年   8篇
  1980年   12篇
  1979年   19篇
  1978年   11篇
  1976年   10篇
  1973年   14篇
  1970年   10篇
  1969年   10篇
排序方式: 共有2708条查询结果,搜索用时 31 毫秒
31.
PURPOSE: Experimental immune-mediated blepharoconjunctivitis (EC) was induced in Lewis rats by immunization with ovalbumin (OVA) in complete Freund's adjuvant (CFA) or aluminum hydroxide [Al(OH)3]. To investigate the affect of genetic factors on the susceptibility of EC, we tested different strains of rats for the development of EC. METHODS: Lewis and Brown Norway (BN) rats were immunized once with 100 microg of OVA in CFA or Al(OH)3. Three weeks later they were challenged with OVA in eye drops; 24 hours after the challenge they were sacrificed and their eyes, blood, and lymph nodes were harvested for histological studies, measurement of OVA-specific antibodies (IgG, IgG1, IgG2a, IgE), and proliferation or cytokine assay, respectively. ELISA was used to detect OVA-specific IgG; passive cutaneous anaphylaxis was used for detecting IgE. RESULTS: EC, OVA-specific IgG, and cellular immunity were induced in Lewis rats by using either adjuvant, whereas IgE was not produced by either adjuvant. In contrast, IgE was produced in BN rats using either adjuvant, whereas cellular immunity was evoked only when CFA was used. Less cellular infiltration as well as cellular proliferation was detected in BN rats immunized with Al(OH)3. In both strains, Al(OH)3 induced a higher IgG1/IgG2a ratio than did CFA. More interferon-gamma by stimulation with OVA was noted in Lewis rats compared to BN rats, whereas interleukin-4 was detected only in BN rats. CONCLUSIONS: The severity of EC evaluated by cellular infiltration was dependent on OVA-specific cellular immunity. Genetic background is more important than adjuvants in determining the nature of EC and immunity.  相似文献   
32.
To evaluate the physiological role of striatal dopamine (DA) during exercise and the mechanism of functional recovery mediated by grafted DAergic neurons, the locomotor ability (treadmill running) and DA turnover were investigated using treadmill running combined with in vivo microdialysis in the intact control rats, 6-hydroxydopamine (6-OHDA) lesioned rats (hemi-parkinsonian model rats) and DAergic cell grafted rats. The 3 groups of rats were trained to run on a straight treadmill at a speed of 1,800 cm/min for 20 min every day for 7 consecutive days. If the rats could not follow the speed they got electrostimulation (ES) from the grid behind the treadmill belt. The numbers of ES rats received during treadmill running were counted to quantify the locomotor ability. Control rats could keep up with the treadmill easily (0-1 ES/10 min), whereas lesioned rats could not follow the speed (80-100 ES/10 min). Most of the grafted rats received only a few ES, but a few received over 100 ES/10 min. Extracellular DA and its metabolites, dihydroxyphenyl acetic acid (DOPAC) and homovanillic acid (HVA), were measured by in vivo microdialysis and high-performance liquid chromatography (HPLC) during and after treadmill running. In control rats the basal levels of DA, DOPAC and HVA were 2.3 fmol/μl, 1,109.8 fmol/μl and 612.2 fmol/μl, respectively. They increased up to 130%, 140% and 160% by running. In 6-OHDA lesioned rats basal values of DA, DOPAC and HVA were less than 10% of controls. We did not perform microdialysis in these rats since they got too much ES during running. In grafted rats that showed good recovery in locomotor ability, DA returned to almost control level (1.9 fmol/μl), but those of DOPAC (127.8 fmol/μl) and HVA (100.2 fmol/μl) were still low. DA, DOPAC and HVA increased up to 130%, 130% and 150% by running in a similar pattern as in intact rats. These results suggest that grafted neurons can release and metabolize DA in the host striatum both tonically and phasically in relation with internal and external stimuli and also suggest that treadmill running ability is a good indicator of DA turnover in the striatum. Thus, the treadmill running test with microdialysis is useful for quantitative evaluation of motor function in grafted animals.  相似文献   
33.
A rare case of the dural AVM mainly around the left petrosal sinus was reported. A 64 years old man was admitted just after the sudden onset of severe headache and nausea. The CT scan revealed subarachnoid hemorrhage in the left ambient cisterns. A small hematoma was also found in the left cerebellar peduncle. External carotid angiogram showed a dural AVM which nidus was located adjacent to the left superior petrosal sinus. Its feeding arteries were as follows; the middle meningeal artery, the artery of foramen rotundum, the accessory meningeal artery, the dural branch of occipital artery and the ascending pharyngeal artery. The voluminous petrosal vein and the dilated cortical veins were identified as drainers and, the portion of the latter appeared as "varix" embedded in the pons, which was clearly delineated by MRI. In the venous phase, stenotic straight sinus and residual Falcine sinus were illustrated. Superselective embolization of the feeding arteries was employed followed by the direct clippings of draining vein. Postoperative course was uneventful. The present case should be classified into the tentorial dural AVM. Only 26 cases of this rarely encountered entity was reported in the literature. Based on both the present and the previously reported cases, the clinical features, treatment and pathogenesis of this disease were briefly discussed.  相似文献   
34.
35.
36.
Zinc deficiency leads to olfactory and gustatory dysfunction, but little is known about the underlying molecular mechanism of this phenomenon. We examined the effect of dietary zinc deficiency on the rat olfactory epithelium. Immunoreactivities of glutathione S-transferase (GST) mu, neuron-specific enolase (NSE) and proliferating cell nuclear antigen (PCNA), and in situ hybridization of GST mu mRNA in the olfactory epithelia were examined under different dietary zinc intake conditions. Adult male rats were fed a zinc-deficient (ZD) diet (0.5 mg zinc/kg diet), whereas control rats, including pair-fed (PF) and zinc-adequate (ad libitum consumption, AL) groups, were fed a zinc-adequate diet (58 mg zinc/kg diet) for 7 wk. We also examined the effect of zinc replacement (ZR) by subsequently feeding half of the ZD group a zinc-adequate diet for 5 wk after the initial 7-wk deprivation. No significant differences in immunoreactivity for NSE in olfactory epithelial receptor cells or for PCNA in basal cells were noted among groups. Intense GST mu immunoreactivity and hybridization signals were observed in olfactory supporting cells of AL, PF and ZR groups, but very minimal or no such signal was noted in ZD rats. Our findings indicated that zinc deficiency reduces GST mu expression in the supporting cells of rat olfactory epithelia but does not affect receptor cell proliferation or maintenance.  相似文献   
37.
Patients with head and neck cancers that produce a high concentration of granulocyte colony-stimulating factor (G-CSF) or patients with esophageal squamous cell carcinomas who have elevated serum interleukin-6 (IL-6) concentrations have been found previously to be at significant risk for tumor invasion to adjacent organs as well as frequent metastases. This suggests that G-CSF and Il-6 enhance the invasiveness and metastatic potential of cancer cells. We studied the in vitro invasiveness of head and neck cancer cell lines with and without recombinant human G-CSF (rhG-CSF) and human IL-6 (hIL-6) in an extracellular matrix membrane system. The degree of invasiveness was affected by incubating cells with hIL-6, but not by pre-incubating the cell-matrix with hIL-6. The maximum concentration of hIL-6 for enhanced invasiveness was approximately 5,000 u/ml. In addition, rhG-CSF enhanced the invasiveness of tumor cells that produced large amounts of G-CSF. The present study also suggests that tumor cells tend to invade and metastasize in an environment rich in hIL-6. Received: 3 November 1997 / Accepted: 1 April 1998  相似文献   
38.
39.
为了检测妇女绝经后发生骨量减少的相关指标进而倡导依据生活方式的特点对绝经后妇女骨质疏松的发生采取相应的预防和护理方针,我们对日本乡村的绝经后妇女(末次月经后六个月或更长时间算起)进行了为期4a的随访。我们运用双能X线骨密度仪(DXA)对腰椎骨密度(BMD)进行检测并对各种变量,包括年龄、绝经时的年龄、骨折史、日常摄奶量以及吸烟习惯进行多元分析,结果表明这些因素对于腰椎骨密度(BMD)的恢复是不相关联的。 在这些变量中,骨折史被证明对于相关人群是最具危险性的,这些对象有高比例的骨量减少(6.6%),其次是不规律的摄奶(13.6%)和吸烟(9.3%)。在护理中使用的作用于足跟骨的检测骨密度的设备被证实与作用于腰椎的DXA设备可以相互替代。依据这些结果,针对居住在日本乡村的绝经后妇女制订了相应的预防骨质疏松的方针。这些卫生指导方针依据特定区域的生活方式而制定并可适用于其他的人群和区域。在本文中,作者列出了不同的有助于预防绝经后妇女出现骨质疏松的方法并进行了调查。  相似文献   
40.
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