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   217175篇
  免费   2880篇
  国内免费   196篇
耳鼻咽喉   1824篇
儿科学   7359篇
妇产科学   3775篇
基础医学   22009篇
口腔科学   2847篇
临床医学   15253篇
内科学   40489篇
皮肤病学   1310篇
神经病学   19873篇
特种医学   10442篇
外科学   35853篇
综合类   2499篇
一般理论   2篇
预防医学   19513篇
眼科学   3359篇
药学   12921篇
中国医学   705篇
肿瘤学   20218篇
  2023年   221篇
  2022年   453篇
  2021年   781篇
  2020年   388篇
  2019年   547篇
  2018年   22453篇
  2017年   17769篇
  2016年   20032篇
  2015年   1529篇
  2014年   1633篇
  2013年   1847篇
  2012年   8724篇
  2011年   22788篇
  2010年   19837篇
  2009年   12384篇
  2008年   21208篇
  2007年   23554篇
  2006年   2503篇
  2005年   4113篇
  2004年   5215篇
  2003年   6167篇
  2002年   4347篇
  2001年   1894篇
  2000年   2184篇
  1999年   1686篇
  1998年   716篇
  1997年   620篇
  1996年   478篇
  1995年   414篇
  1994年   402篇
  1993年   333篇
  1992年   1151篇
  1991年   1012篇
  1990年   1031篇
  1989年   1021篇
  1988年   890篇
  1987年   877篇
  1986年   805篇
  1985年   803篇
  1984年   555篇
  1983年   446篇
  1982年   246篇
  1980年   227篇
  1979年   487篇
  1978年   287篇
  1977年   256篇
  1974年   242篇
  1971年   231篇
  1969年   250篇
  1968年   233篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Background The purpose of the study was to investigate the brightness of the xenon/bandpass light in vitrectomy and assess its phototoxic effects using A2E-laden retinal pigment epithelial (RPE) cells. Methods The total luminous flux and spectral irradiance of 20- and 25-gauge endoilluminators connected to xenon lamps were measured and compared to those of 20- and 25-gauge endoilluminators connected to a halogen lamp. In vitro, A2E-laden cells were evenly exposed to xenon/bandpass light for 5 to 30 min positioned at 1 cm and 2 cm for a standard light probe and an implantable “chandelier” light probe, respectively, above the cells, and the cell viability was assessed using WST-1 assay. The cell viability was compared with cells exposed to 30 min of halogen light projected through a 20-gauge endoilluminator. Results The maximal total luminous flux of xenon/bandpass light emitted through the 20-gauge endoilluminator was 2.8 times higher than that of the halogen light. The total luminous flux of the 25-gauge endoilluminators was 0.6-1.1 times greater than the 20-gauge endoilluminators connected to the halogen light. The viability of the A2E-laden cells after exposure to the xenon/bandpass light was no different than that of the cells exposed to the halogen light when the total luminous flux of these lights was at the same level. Xenon/bandpass light from an implantable “chandelier” light probe induced A2E-mediated RPE damage to a similar extent as that of the halogen light through a 20-gauge endoilluminator. Conclusions A2E-mediated phototoxicity of xenon/bandpass light is comparable to that of halogen light.  相似文献   
992.
BACKGROUND/AIMS: To determine the levels of cyclosporin A (CsA) in tears and the anterior segment of the eye following long-term oral intake for autoimmune diseases. METHODS: Subjects taking oral CsA to treat relapsing autoimmune ocular inflammation were included in this study. All of the patients had been quiescent for at least 6 months. In patients scheduled for cataract extraction (group A), the CsA levels in the blood, aqueous humour and anterior capsule of the lens were determined. In subjects not requiring surgical intervention (group B), CsA was measured in tears and blood. The samples were analysed using turbulent flow chromatography coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS: There were 19 subjects in group A and 43 subjects in group B. CsA was detectable in all of the tear samples with a mean value of 22.4 +/- 20.2 ng/ml and there was a significant positive correlation between the CsA levels in tears and blood (P = 0.012). CsA was not detected in any of the surgical samples. CONCLUSION: LC-MS/MS proved very sensitive for detecting CsA in low-volume biological samples. CsA was present in human tears in proportion to the blood level after an average of 12 hours from the last oral intake.  相似文献   
993.
An adolescent with complaints of fatigue, tachycardia, abdominal discomfort, and blood-stained diarrhea is presented. Clinical and laboratory evaluation revealed a microcytemic anemia with iron deficiency, beta thalassemia, and thyrotoxicosis with thyroid antibodies. Crohn’s disease was confirmed on endoscopy. A rapid normalization of clinical and laboratory parameters was observed following the initiation of therapy and further exacerbation of her illness was prevented. Although the simultaneous occurrence of Crohn’s disease, autoimmune thyroiditis, and a beta-thalassemia trait is likely to be coincidental, the combination of an autoimmune thyroid disease and Crohn’s disease is rare in pediatrics. Several issues of importance in the treatment of these conditions are discussed. Rectal blood loss associated with Crohn’s disease may lead to severe iron deficiency, especially in patients with preexistent beta-thalassemia trait, and those with thyroiditis are prone to developing hypothyroidism following treatment, requiring that they be monitored closely.  相似文献   
994.
We report autologous CD34+ cell transplantation performed in 3 cases of recurrent breast cancer. The hematological recovery in these cases was assessed by comparing with that in the previous cases of autologous hematopoietic stem cell transplantation performed with the same high-dose chemotherapy regimen. Patient 1 was a 32-year-old woman with pulmonary and skeletal metastases; patient 2, a 55-year-old woman with pulmonary metastases; and patient 3, a 48-year-old woman with hepatic metastases. On day 1, cyclophosphamide 1000 mg/m2 and epirubicin 130 mg/m2 were administered concurrently with granulocyte colony-stimulating factor, and peripheral blood stem cells were harvested on days 14-16. These stem cells were processed using anti-CD34 monoclonal antibody and an immunomagnetic bead device, Isolex 300i. The high-dose chemotherapy regimen consisted of cyclophosphamide 2000 mg/m2/day, div, and thiotepa 200 mg/m2/day, div on day -5, -4, and -3. The harvested CD34+ cells numbered 3.9 +/- 2.8 x 10(6)/kg (range: 0.73-7.8/10(6)/kg), and the CFU-GM, 8.3 +/- 5.6 x 10(5)/kg (range: 1.2-15.1/10(5)/kg). After the separation, the percent of CD34+ cells was 81.9 +/- 11.6% (range: 65.8-96.4%), the CD34+ cell yield, 71.8 +/- 30.2% (range: 46.0-129.6%), and the CFU-GM yield, 48.9 +/- 9.1% (range: 35.3-62.0%). At the time of transplantation, the number of nucleated cells was 0.55 +/- 0.31 x 10(5)/kg, and that of CFU-GM, 31.2 +/- 17.8 x 10(5)/kg. Comparison of the hematological recovery in these three cases with that in patients receiving an identical high-dose chemotherapy regimen revealed recovery rates significantly faster than in patients having bone marrow transplants, and approximately identical with that in peripheral blood stem cell transplantation cases.  相似文献   
995.
α1-Adrenoceptors mediate contraction of iris dilator smooth muscle and hence pupil dilatation. We compared the ability of i.v. bolus injections of alfuzosin, doxazosin, naftopidil, prazosin, tamsulosin and terazosin to antagonise phenylephrine-induced mydriasis relative to their potency for inhibiting phenylephrine-induced elevations of intraurethral pressure (IUP) in rabbits. Moreover, we compared the ability of these drugs to induce miosis in conscious rabbits in the absence of phenylephrine. All antagonists inhibited the effects of phenylephrine on pupil size and IUP, and the ratio of the respective ED50 values was close to unity in all cases. The doses required to induce statistically significant miosis in the absence of phenylephrine were 30- to 100-fold higher than those inhibiting phenylephrine-induced mydriasis for all antagonists, except for naftopidil. Moreover, the miotic effects of all α1-adrenoceptor antagonists were fully reversible within 8 h. We conclude that alfuzosin, doxazosin, naftopidil, prazosin, tamsulosin and terazosin inhibit phenylephrine-induced mydriasis in the same dose range as they inhibit elevations in IUP. Higher doses of all antagonists are required to induce miosis in the absence of an exogenous agonist, and such miosis is always reversible within hours.  相似文献   
996.
Granisetron is a selective 5-HT3 receptor antagonist that is used therapeutically for the prevention of vomiting and nausea associated with emetogenic cancer chemotherapy. Although forms of the drug are commercially available for intravenous and oral dosage, there is a need for intranasal delivery formulations in specific patient populations in which the use of these dosage forms may be unfeasible and/or inconvenient. A rapid and specific high-performance liq uid chromatography method with mass spectrometric detection (LC-MS) was developed and validated for the analysis of granisetron in plasma after nasal administration in rats. Granisetron was separated in a reverse-phase C-18 column without interference from other components of plasma. This method involves a rapid assay for the determination of granisetron in a small volume of plasma with a run time of 12 min using ondansetron as an internal standard. Data were acquired in the electrospray ionization (ESI) mode with positive ion detection and application of single ion recording (SIR). Granisetron and ondansetron were detected at m/z values of 313.2 and 294.2, respectively. The method described was found to be suitable for the analysis of all samples collected during preclinical pharmacokinetic investigations of granisetron in rats after nasal administration. To date, the first pharmacokinetic study after intranasal administration of granisetron was performed and some pharmacokinetic parameters were presented in this paper. Granisetron was found to be well absorbed through nasal route and the bioavailability of this drug following nasal administration was comparable with that of intravenous administration.  相似文献   
997.
998.
999.
收集、整理并总结了中国知网、重庆维普、万方三大中文数据库中关于拔罐疗法的医学文献,检索标题或关键词为"拔罐"或"走罐"或"闪罐"或"刺络拔罐"或"药罐",搜索范围为1953年至2015年7月15日收录的医学文献。从拔罐疗法的临床表现形式、临床适应症及机制研究进展三个方面进行总结和探讨,力求从临床应用及作用机理研究两个不同角度对拔罐疗法做全面详尽的综述。文献分析结果表明拔罐疗法发展至今有多种表现形式,治疗疾病范围涵盖内、外、妇、儿多个学科,其作用机制主要是负压吸引、提升痛阈、增加皮肤血流量及增强机体免疫力。  相似文献   
1000.

Objective

To observe the clinical efficacy of Governor Vessel-unblocking and brain-refreshing scalp acupuncture for cerebral palsy (CP) complicated with intellectual disabilities.

Methods

A total of 300 CP cases aged between 1 and 5 years were randomly allocated into a treatment group (n=150) and a control group (n=150). Patients in the treatment group were treated with Governor Vessel-unblocking and brainrefreshing scalp acupuncture combined with rehabilitation training, whereas patients in the control group received rehabilitation training alone. The Beijing Gesell developmental (Gesell) scale and gross motor function measure (GMFM) scale were used to assess the motor and intellectual development before and 3 months after the treatment. In addition, the head CT/MRI examination was applied to assess the brain nerve repair before and after the treatment.

Results

After the treatment, the total effective rate in the treatment group was 78.0%, versus 42.7% in the control group, showing a statistical significance (P<0.05). As for scores of five subscales in the Gesell scale, there were significant intra-group differences in the treatment group (all P<0.05); and the scores in the treatment group were significantly better than those in the control group (all P<0.05). As for scores of five dimensions in GMFM scale, there were significant intra-group differences in the treatment group (all P<0.05); and the scores in the treatment group were significantly better than those in the control group (all P<0.05). According to the head CT/MRI findings, the total effective rate was 73.3% in the treatment group, versus 62.0% in the control group, showing a statistical significance (P<0.05).

Conclusion

When used in combination with rehabilitative training, Governor Vessel-unblocking and brain-refreshing scalp acupuncture can significantly improve the clinical efficacy for cerebral palsy complicated with intellectual disabilities. It can also improve the patients’ motor function, intelligence and language ability.
  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