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   35547篇
  免费   2794篇
  国内免费   1287篇
耳鼻咽喉   130篇
儿科学   869篇
妇产科学   850篇
基础医学   9327篇
口腔科学   476篇
临床医学   3081篇
内科学   5636篇
皮肤病学   684篇
神经病学   2130篇
特种医学   555篇
外国民族医学   5篇
外科学   2150篇
综合类   4787篇
现状与发展   8篇
一般理论   7篇
预防医学   2710篇
眼科学   379篇
药学   2511篇
  10篇
中国医学   679篇
肿瘤学   2644篇
  2024年   54篇
  2023年   513篇
  2022年   585篇
  2021年   1231篇
  2020年   1125篇
  2019年   1152篇
  2018年   1019篇
  2017年   1041篇
  2016年   1163篇
  2015年   1193篇
  2014年   1733篇
  2013年   2412篇
  2012年   1676篇
  2011年   1961篇
  2010年   1500篇
  2009年   1591篇
  2008年   1571篇
  2007年   1644篇
  2006年   1539篇
  2005年   1411篇
  2004年   1275篇
  2003年   1195篇
  2002年   1020篇
  2001年   895篇
  2000年   791篇
  1999年   659篇
  1998年   678篇
  1997年   679篇
  1996年   621篇
  1995年   684篇
  1994年   578篇
  1993年   529篇
  1992年   521篇
  1991年   479篇
  1990年   406篇
  1989年   310篇
  1988年   310篇
  1987年   258篇
  1986年   229篇
  1985年   389篇
  1984年   263篇
  1983年   194篇
  1982年   139篇
  1981年   120篇
  1980年   88篇
  1979年   68篇
  1978年   50篇
  1977年   16篇
  1976年   28篇
  1974年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
本文对以重组淋球菌IgA蛋白酶为抗原制备的7株特异性McAb的特性进行了初步研究。结果有5株(1C8、1E5、1F11、1G3和2E6)能中和淋球菌IgA蛋白酶活性。经相加试验初步证明,其中1F11、2G3与其它3株McAb的作用位点不同。因此,淋球菌IgA蛋白酶至少存在3个中和表位。  相似文献   
82.
Aims : Adenocarcinomas account for about 60% of metastatic cancers of unknown primary (CUP) site. In such a clinical CUP situation, histopathologists are challenged to differentiate renal cell carcinomas (RCC) from other adenocarcinomas with similar immunophenotypes, especially chemotherapeutically treatable mammary and ovarian carcinomas. Methods and results : Recently, we produced a monoclonal antibody (mAb), designated 138H11, against human gamma-glutamyltransferase (γGT), which stained over 98% primary clear cell and chromophilic RCC on frozen sections. The 138H11 epitope could not be stained using conventional techniques in most paraffin-embedded sections of the same origin, due to destruction by formalin fixation below the detection level. Here, we demonstrate that mAb 138H11 can specifically stain γGT in paraffin-embedded primary and metastatic RCC after enhancement with an ultrasensitive immunohistochemical method. We analysed a selected subgroup of adenocarcinomas with immunophenotypes which would not allow a differentiation from RCC in a CUP situation. We found a predominantly membranous expression of the 138H11 target antigen in 26/51 primary RCC and 15/34 metastatic RCC. In contrast, all 43/43 primary ovarian and bronchial carcinomas as well as 54/54 metastases of ovarian, mammary, bronchial and gastric carcinomas were negative for mAb 138H11. Conclusions : The data suggest that mAb 138H11 is useful for the immunohistochemical differentiation of RCC from other metastatic adenocarcinomas if the primary site of the tumour is not known.  相似文献   
83.
重症肌无力中枢神经系统受损模型   总被引:26,自引:2,他引:24  
目的近年研究结果表明,重症肌无力(MG)病变部位并不仅仅局限于神经肌接头(NMJ)处突触后膜烟碱型乙酰胆碱受体(nAChR),烟碱型乙酰胆碱受体抗体(AChR-ab)病理作用可能波及到中枢神经系统(CNS)。因此,有必要建立模拟MG患者CNS损害的动物模型,研究MG患者脑脊液中存在的AChR-ab引起CNS损害的机制。方法从MG患者血中提取的AChR-ab经侧脑室穿刺注入到大鼠脑室系统,然后观察其症状和体征,以及用脑干听觉诱发电位仪(BAEP)检测鼠脑干听觉传导中枢功能。用免疫组化法(ABC)研究AChR-ab与CNS神经-nAChR之间免疫结合反应及其分布。结果大鼠除了出现脑干听觉传导中枢功能障碍外,还出现类似于MG动物模型表现的症状。免疫组化研究结果显示,神经-nAChR样阳性免疫反应广泛分布于CNS许多部位。结论脑室内注入的AChR-ab与神经-AChR结合引起CNS功能障碍和出现MG动物模型样症状。我们首次建立的中枢受损的MG模型将有助于阐明AChR-ab引起中枢受损和CNS下位运动神经元引起横纹肌收缩无力的机制。  相似文献   
84.
用快速双抗体夹心ELISA检测囊虫病人血清中的循环抗原,其阳性率为67.5%;正常人血有的假阳性率为5.33%;包虫、肝吸虫和弓形虫病人血清的交叉反应率分别为6.9%、7.5%和12.5%。结果表明.该法与常规双抗体夹心ELISA相比具有较为敏感、快速、稳定和节省血清、试剂用量的优点,但其特异性有待进一步提高。用快速双抗体夹心ELISA和间接型ELISA检测第1至10疗程囊虫病人血清中的循环抗原和抗体,表明检测循环抗原考核囊虫病人的治疗效果优于检测抗体  相似文献   
85.
Purpose. The purpose of this study is to highlight the importance of knowing the glass transition temperature, Tg, of a lyophilized amorphous solid composed primarily of a sugar and a protein in the interpretation of accelerated stability data. Methods. Glass transition temperatures were measured using DSC and dielectric relaxation spectroscopy. Aggregation of protein in the solid state was monitored using size-exclusion chromatography. Results. Sucrose formulation (Tg ~ 59°C) when stored at 60°C was found to undergo significant aggregation, while the trehalose formulation (Tg ~ 80°C) was stable at 60°C. The instability observed with sucrose formulation at 60°C can be attributed to its Tg (~59°C) being close to the testing temperature. Increase in the protein/sugar ratio was found to increase the Tgs of the formulations containing sucrose or trehalose, but to different degrees. Conclusions. Since the formulations exist in glassy state during their shelf-life, accelerated stability data generated in the glassy state (40°C) is perhaps a better predictor of the relative stability of formulations than the data generated at a higher temperature (60°C) where one formulation is in the glassy state while the other is near or above its Tg.  相似文献   
86.
异常孕产史妇女风疹病毒感染的研究   总被引:4,自引:0,他引:4  
目的了解孕妇风疹病毒的感染率;为早期预测异常妊娠的出现、及时防治提供理论依据。方法采用酶联免疫吸附法(ELISA)检测206例有异常孕产史妇女和810例正常孕妇血清中特异性抗风疹IgM抗体。结果有异常孕产史的妇女风疹病毒感染率明显高于对照组(x2=11.33P<0.01)。结论风疹病毒感染是造成异常妊娠的主要原因之一;孕前或孕早期进行风疹病毒感染的检测,对降低异常妊娠的出现具有重要意义。  相似文献   
87.
88.
Multiple pregnancies resulting from ovarian stimulation areat a higher risk of carrying at least one fetus affected byMendelian or chromosomal anomalies, the incidence of which isdirectly related to the order of multiples. Genetic analysisbefore fetal reduction was offered to both high-and low-riskpregnant women carrying two or more fetuses after ovulationinduction. Chorionic villus sampling (CVS) and fetal reductionwere achieved by transabdominal needling. The use of short-termculture, the polymerase chain reaction and fresh tissue enzymaticanalyses have made it possible for genetic diagnosis to be availablein a few days. A total of 100 patients had multifetal pregnancyreduction performed by a single operator; all of them completedpregnancy and none was lost at follow-up. The total fetal lossbefore 24 weeks was 7% and no statistically significant relationshipwas found with the final number of fetuses and CVS. Perinatallosses (3.9%) were only present in the series with a final numberof two fetuses. Pregnancy duration and birthweight were significantlyhigher in singletons than in twins, but were not related toCVS. The rate of chromosomal disorders was higher (7.2%) inthe study series than in singleton pregnancies not undergoingfetal reduction. Diagnostic error due to incorrect samplingwas reported in 1.5% of cases. These data support fetal reductionas a valuable strategy to improve the outcome of multiple pregnancy.The outcome of pregnancies reduced to singletons was significantlybetter than of those reduced to twins, and was not related toCVS. Therefore, prenatal genetic diagnosis should become anintegral part of counselling on multiple pregnancy, and is stronglyrecommended when reduction to singleton pregnancy is requested.  相似文献   
89.
My experience with more than 80 cases of the late infantile and juvenile forms of the neuronal ceroid-lipofuscinoses over the last 5 years has led to the following realizations. The 2 variants are neurologically distinct entities and probably are the result of different genetic defects. Treatment includes supportive measures and anticonvulsant medication. Therapy for behavioral and psychiatric disturbances in the juvenile type proves to be particularly challenging as neuroleptic medications tend to worsen parkinsonian like symptoms. Neuropathologic and neuro radiologic explanation of clinical symptomatology correlates best with neuronal loss and not neuronal storage. There is a paucity of neuropathologic documentation of these 2 types; additional reports are encouraged.  相似文献   
90.
通过细胞融合技术,筛选出MAL-1和MAL-2两株抗莱氏支原体(A.Laidlawii,A.L)单克隆抗体(单抗)。通过SDS-PAGE和Western印迹法测得单抗相对应的抗原分子量均为67.46ku。用间接免疫荧光法(IFA)检测,单抗与细胞培养中另外3种常见污染的支原体和呼吸道肺炎支原体无交叉反应。将单抗用于检测支原体污染的细胞培养物,结果表明,此单抗能特异性地检出莱氏支原体。故可用其推断支原体污染途径,便于制定防治措施。  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