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   41442篇
  免费   3430篇
  国内免费   1188篇
耳鼻咽喉   618篇
儿科学   811篇
妇产科学   587篇
基础医学   5578篇
口腔科学   513篇
临床医学   4095篇
内科学   7115篇
皮肤病学   1560篇
神经病学   2504篇
特种医学   2349篇
外科学   4539篇
综合类   3415篇
现状与发展   5篇
一般理论   6篇
预防医学   2605篇
眼科学   866篇
药学   4130篇
  21篇
中国医学   1741篇
肿瘤学   3002篇
  2024年   76篇
  2023年   299篇
  2022年   961篇
  2021年   1682篇
  2020年   1085篇
  2019年   1049篇
  2018年   1178篇
  2017年   1122篇
  2016年   1476篇
  2015年   2143篇
  2014年   2569篇
  2013年   2937篇
  2012年   4099篇
  2011年   4016篇
  2010年   2826篇
  2009年   2375篇
  2008年   2740篇
  2007年   2556篇
  2006年   2216篇
  2005年   1875篇
  2004年   1421篇
  2003年   1258篇
  2002年   1036篇
  2001年   524篇
  2000年   433篇
  1999年   262篇
  1998年   168篇
  1997年   150篇
  1996年   117篇
  1995年   97篇
  1994年   60篇
  1993年   65篇
  1992年   67篇
  1991年   89篇
  1990年   53篇
  1989年   59篇
  1988年   75篇
  1987年   56篇
  1986年   35篇
  1985年   33篇
  1983年   28篇
  1979年   35篇
  1978年   28篇
  1977年   30篇
  1965年   40篇
  1964年   31篇
  1959年   48篇
  1958年   53篇
  1957年   65篇
  1956年   28篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
91.
Effects of sodium salts of various monovalent inorganic anions on transdermal permeation of salicylic acid were investigated. In in-vitro experiment using a Franz-type diffusion cell and excised mouse skin, the permeation-enhancing activities of the sodium salts of inorganic anions were roughly proportional to lyotropic Hofmeister swelling abilities of the anions; F?<SO4 2?<Cl? <ClO4 ?<NO3 <SCN? <Br <I?, i.e. l, Br and SCN increased the flux of drugs through the mouse skin, while F?, SO4 2?, Cl?, ClO4 ? and NO3 ? decreased or did not affect the flux. In invivo experiment using the rabbit as the test animal, the plasma concentration of salicylic acid of the rabbit to which 10%-salicylic acid ointment containing 5%-Nal or NaBr was applied was significantly higher than that of the rabbit to which the ointment without the electrolytes was applied. The amounts of sterol leached out of stratum corneum sheet when the sheet was immersed in aqueous solutions of Nal, NaBr, or NaSCN were much more than that of stratum corneum immersed in aqueous solutions of the other inorganic anions. The FTIR/ATR spectroscopy showed that the peaks at 2853 cm?1 and 2924 cm?1 in the IR absorption spectrum of the stratum corneum sheet of the mouse were shifted to higher frequencies by the anions which enhanced the transdermal drug permeation, while not shifted by the anions which did not have any permeation-enhancing activities or have permeation-reducing activities. These results suggest that sodium salts of some anions such as iodide, bromide and thiocyanate enhance transdermal permeation of salicylic acid through swelling and perturbation of the skin structure by these anions.  相似文献   
92.
93.
常双海 《中国民康医学》2006,18(12):1020-1021
目的评价国产丁二酸洛沙平治疗精神分裂症的临床疗效与安全性.方法 随机临床对照研究,分别给予丁二酸洛沙平与利培酮治疗8周,采用BPRS和CGI评定临床疗效,并记录不良反应.结果试验结束时两组疗效相似,有效率均大于85%,显效率约60%.洛沙平组的BPRS减分率在治疗早期大于维思通组,即洛沙平的起效时间早于维思通.两组的主要不良反应相当,以静坐不能、肌张力增高、震颤和心动过速为主,加用安坦和/或心得安后均可缓解,不影响继续治疗.结论洛沙平是一种疗效肯定的抗精神病药物,起效快、安全,可作为治疗精神分裂症的药物在临床应用.  相似文献   
94.
We quantified the financial implications of surgical complications following pancreas transplantation. We reviewed medical and financial records of 49 pancreas transplant recipients at the University of Michigan Health System (UMHS) between 1/6/2002 and 11/22/2004. The association of donor, transplant recipient and financial variables was assessed. The median costs to UMHS of procedures and follow-up were $92,917 for recipients without surgical complications versus $108,431 when a surgical complication occurred, a difference of $15,514 (p = 0.03). Median reimbursement by the payer was $17,363 higher in patients with a surgical complication (p = 0.001). Similar trends (higher insurer costs) were noted when stratifying by payer (public and private) and specific procedure (SPK and PAK). All parties (patient, physician, payer and medical center) should benefit from quality improvement, with payers having a financial interest in pancreas transplant surgical quality initiatives.  相似文献   
95.
Increased expression of the sodium iodide symporter (NIS) is required for effective radioiodine treatment and reporter gene imaging of breast cancer. We investigated the effect of retinoic acid on adenovirus-mediated expression of the human NIS gene in the MCF-7 breast cancer cell line. METHODS: The MCF-7 cell line was infected with recombinant adenovirus carrying the human NIS gene (Rad-NIS). Levels of NIS messenger RNA (mRNA) and protein expression and radioiodine ((125)I) uptake were measured to evaluate adenovirus-mediated NIS gene expression in wild-type and Rad-NIS-infected MCF-7 cells after treatment with all-trans-retinoic acid (ATRA; 10(-8)-10(-6) mol/L). RESULTS: The transduction efficiency of adenovirus in MCF-7 cells at a multiplicity of infection (MOI) of 50 was >60%. After incubation with 10(-6) mol/L ATRA, the mRNA level in Rad-NIS-infected MCF-7 cells increased to 118.5 times that of wild-type MCF-7 cells, whereas the mRNA level in wild-type MCF-7 cells showed only a 2.1-fold increase. Western blot, immunocytochemical staining, and flow cytometry analyses showed that NIS protein expression in MCF-7 cells infected with Rad-NIS increased after ATRA treatment. With ATRA treatment, the amount of (125)I uptake increased in a dose-dependent manner (P < 0.001). The (125)I uptake in wild-type MCF-7 cells increased 3.1-, 5.5-, and 7.6-fold with treatment with 10(-8), 10(-7), and 10(-6) mol/L ATRA, respectively. Rad-NIS-infected cells showed a 4.0-fold increase in (125)I uptake. Treatment of Rad-NIS-infected cells with 10(-8), 10(-7), and 10(-6) mol/L ATRA increased (125)I uptake by 4.9-, 8.2-, and 27.6-fold, respectively, compared with wild-type MCF-7 cells. The level of NIS expression in Rad-NIS-infected MCF-7 cells treated with 10(-6) mol/L ATRA (245.0 +/- 13.7 pmol/10(6) cells) was much greater than the sum of the expression levels seen in ATRA-treated wild-type cells and Rad-NIS-infected wild-type cells. CONCLUSION: Retinoic acid increases adenovirus-mediated NIS expression in MCF-7 cells. Our results indicate that improved efficiency of NIS gene therapy or reporter imaging in breast cancer may be possible with retinoic acid treatment.  相似文献   
96.
We developed a technique of translocation of the pulmonary artery anterior to the ascending aorta without transection of the aorta in the repair of tetralogy of Fallot with absent pulmonary valve. Our technique includes detachment of the main pulmonary artery (MPA) from the pulmonary annulus, vertical division of the MPA, anterior translocation of the pulmonary artery with patch augmentation between the vertically divided MPA.  相似文献   
97.
98.
目的观察CO中毒致迟发性脑病(DNS)大鼠脑内CD4^+T淋巴细胞浸润以及神经胶质酸性蛋白(GFAP)的表达情况,探讨CO中毒致DNS的病理过程。方法25只SD雄性大鼠随机分为对照组、染毒后3、7、10、20d组,每组5只。采用HE和免疫组织化学染色方法,观察染毒后各时间点大鼠脑内病理形态学变化,及CD4^+T淋巴细胞浸润和GFAP的表达情况。结果HE染色结果显示:各染毒组在大脑皮层及海马均出现神经细胞不同程度的变性、坏死,染毒后7d组最重。免疫组织化学染色结果显示:对照组无CD4^+T淋巴细胞浸润,有少量GFAP表达;各染毒组不同脑区CD4^+T淋巴细胞、GFAP均有不同程度的浸润和表达。CD4^+T淋巴细胞染毒后3d开始浸润,7d达峰值,两者在数量上差异有统计学意义(P〈0.01)。各组染毒后GFAP均有大量表达,随染毒时间延长表达数量呈上升趋势。结论CD4^+T淋巴细胞可能参与了CO中毒致DNS的免疫病理过程,GFAP阳性细胞对CO中毒引发的DNS可能具有保护作用。  相似文献   
99.
目的探讨突触蛋白-I(synapsin-I)在胚胎干细胞(ESCs)体外神经分化过程中的表达变化及作用。方法采用“五步法”和维甲酸(RA)法两种途径体外诱导ESCs向神经细胞分化,并以另一种可向神经细胞分化的肿瘤细胞-PC12细胞的诱导过程作参照,从不同的途径、不同的细胞进行比较.通过免疫组织化学、RT-PCR、Western blot方法观察这一过程中synapsin-I的表达变化.找出synapsin-I在ESCs向神经细胞分化过程中表达变化的共同规律。结果结合形态学和其它神经特异性指标的变化,synapsin-I在ESCs和PC12细胞向神经细胞分化的过程中具有早期即有表达,后逐渐升高,至分化成熟阶段达最高,后期又逐渐下降的变化规律。结论在ESCs的分化过程中,synapsin-I的表达存在特定的时空规律,并与ESCs的形态学改变相关,提示synapsin-I可能对ESCs在神经分化过程中的形态分化起着重要的作用。  相似文献   
100.
实践决定认识,认识的差异也便决定于实践差异。中医学和西医的认识差异巨大,其中存在诸多因素,但是实践差异必定是决定性因素之一。本文从多方面分析了中医的实践特点,并基于中医的实践特点论证了其对中医特殊认识的决定作用。为说明问题,同时与西医实践进行了比较。  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