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   6088篇
  免费   331篇
  国内免费   25篇
耳鼻咽喉   45篇
儿科学   349篇
妇产科学   108篇
基础医学   720篇
口腔科学   103篇
临床医学   443篇
内科学   1310篇
皮肤病学   69篇
神经病学   466篇
特种医学   118篇
外科学   913篇
综合类   151篇
一般理论   4篇
预防医学   322篇
眼科学   209篇
药学   655篇
中国医学   84篇
肿瘤学   375篇
  2023年   41篇
  2022年   76篇
  2021年   225篇
  2020年   97篇
  2019年   151篇
  2018年   190篇
  2017年   135篇
  2016年   147篇
  2015年   177篇
  2014年   249篇
  2013年   340篇
  2012年   454篇
  2011年   490篇
  2010年   278篇
  2009年   236篇
  2008年   356篇
  2007年   341篇
  2006年   282篇
  2005年   278篇
  2004年   228篇
  2003年   196篇
  2002年   203篇
  2001年   90篇
  2000年   94篇
  1999年   90篇
  1998年   65篇
  1997年   29篇
  1996年   42篇
  1995年   31篇
  1993年   28篇
  1992年   47篇
  1991年   61篇
  1990年   61篇
  1989年   46篇
  1988年   41篇
  1987年   50篇
  1986年   31篇
  1985年   53篇
  1984年   35篇
  1983年   28篇
  1982年   24篇
  1981年   17篇
  1980年   18篇
  1979年   20篇
  1978年   25篇
  1977年   21篇
  1973年   24篇
  1972年   17篇
  1971年   19篇
  1969年   21篇
排序方式: 共有6444条查询结果,搜索用时 15 毫秒
71.
Kathirvel S  Prakash A  Lokesh BN  Sujatha P 《Anesthesia and analgesia》2000,91(4):1029-31, table of contents
Implications: This case report describes the anesthetic considerations for a patient with paroxysmal nocturnal hemoglobinuria. Specific strategies to be applied in the perioperative period to prevent hemolytic episodes and venous thrombosis are also discussed.  相似文献   
72.
Anemia remains a significant worldwide public health problem. Most studies of anemia and iron deficiency, the major cause of anemia, have targeted small children and reproductive age women. Much less is known about anemia in other lifecycle groups, especially preschool age children, prepubertal boys and girls, or in older adults. Yet recent studies indicate that anemia may increase the risk for chronic diseases and accelerate declining function in older adults. We examined anemia throughout the lifecycle in Kuwait by analyzing data from the 2002 Kuwait Nutrition Surveillance Program. Over 13,000 individuals of both sexes representing all ages were studied. The prevalence of anemia was higher in females than males between 6 months and 3 years. From age 4 to 14 years, there was a reversal with males having a higher rate of anemia. Older females had a lower prevalence of anemia than younger females. These results imply certain policy options.  相似文献   
73.
腹腔镜下精索血管高位离断后大鼠睾丸的形态学改变   总被引:1,自引:2,他引:1  
目的观察腹腔镜FowlerStephens(FS)手术对青春发育前、中、后期睾丸形态结构的影响。方法30d龄Wistar大鼠麻醉后建立CO2气腹,分别行右侧精索血管游离术(对照组)、右侧腹腔内精索血管离断术(FS组),术后将每大组大鼠再分成7个小组(对照组每小组5只;FS组每小组8~12只),分别在术后第9d(青春发育期前)、20d和45d(青春发育期)、90d和180d(性发育成熟期)、360d和540d(中年期),获取睾丸进行详尽的组织形态学研究。结果FS手术可以引起术后不同时期共85%手术侧睾丸出现轻度(血睾屏障受损为主)、重度(唯支持细胞综合征为主)和完全萎缩(丧失睾丸基本结构,无生殖细胞存活);当轻度或重度萎缩,对侧睾丸未受累;当完全萎缩(49%),对侧睾丸在手术45d后,100%出现轻度(青春发育期后)或重度(中年期)萎缩;间质细胞增生或腺瘤可发生于轻、重和完全萎缩睾丸中(P<0.001)。结论腹腔镜FS动物模型可用幼年大鼠建立;该手术可以引起从青春发育前期至中年期较高比例、不同程度的睾丸萎缩,其中完全萎缩可以影响到对(健)侧睾丸,而可能引起青春发育期后生殖力下降或丧失;睾丸间质肿瘤可以较高比例地发生于不同程度萎缩睾丸中。  相似文献   
74.
Efficacy of misoprostol was studied for induction of labor at term. Seventy patients were randomized to Group A (n = 36, oral misoprostol 50 microg four hourly to maximum of 5 doses) and B (n = 34, continuous oxytocin infusion). Induction-delivery interval was shorter with misoprostol (7.7 +/- 2.8 h against 14.3 +/- 4.8 h with oxytocin) but the rates of vaginal delivery, cesarean, neonatal outcome variables were similar. Hence, misoprostol is an effective agent for induction of labor at term.  相似文献   
75.
Intrinsic signal imaging (ISI) measures changes in light reflectance from the illuminated cortex (intrinsic signals or IS) attributed to various vascular and metabolic sources that, when using illumination in the 600 nm range, appear to co-localize with neuronal activity. Given the multiple sources contributing to the collected IS, the common practice of averaging across an extended post-stimulus time epoch before dividing by baseline data typically visualizes evoked IS overlying both the cortical tissue and the large surface blood vessels. In rat PMBSF, the contribution from these vessels are problematic as they do not co-localize with known PMBSF function. Determining a means for quantifying the evoked IS area poses an additional challenge. Here, we describe how exploiting IS collected shortly after stimulus onset (within 1.5 s), which coincides with fast oxygen consumption of active neurons, visualizes evoked IS overlying the cortical tissue without the large surface vessels. We also describe how the use of absolute thresholds combined with a baseline determined from data collected immediately prior to stimulus onset (within 1 s) targets most precisely a specific evoked IS amplitude, a method that should be especially useful when evoked areas are expected to occupy a substantial portion of the total imaged area and/or when peak activity is expected to differ between subjects.  相似文献   
76.
We have used pathway-specific cDNA arrays coupled with analysis of gene promoter regions to identify novel genes that may mediate the toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the thymus. C57BL/6 mice were injected ip with 50 microg/kg TCDD, and 3, 6, or 24 h later, RNA was extracted from the thymus and subjected to microarray analysis. Several members of the TNF and TNFR family were induced following TCDD exposure, including receptor/ligand pairs Ltbeta-R/LIGHT, OX40/OX40L and TNF-alpha/TNFR1. In addition, Fas and CD30 were also upregulated. Pro-apoptotic bcl-2 gene family members Bax and Hrk, among others, were also induced, as were pro-survival bcl-2 family genes Bcl-x and Bcl-w. Cell-cycle regulator p21Cip1 was also induced. In addition, we analyzed the promoter regions of genes induced by TCDD for the presence of dioxin-responsive elements (DREs). The Fas and LIGHT gene promoters were found to contain DREs as analyzed by Matinspector Web-based search algorithm. Furthermore, binding of the aryl hydrocarbon receptor (AhR) to the DREs present on these genes was confirmed by chromatin immunoprecipitation. Given that several of the genes, including Fas, LIGHT, and CD30 are involved in negative selection of T cells in the thymus, our studies suggest that TCDD-induced upregulation of these genes may enhance negative selection leading to thymic atrophy.  相似文献   
77.
78.
Embryonic stem cell (ES) technology has advanced considerably within the past three decades and has gained prominent distinction within the emerging field of regenerative medicine. As it now enters the nascent stages of clinical application, many hopes and expectations arise along with questions as to where the technology will go. This paper evaluates the technical and practical obstacles that must be overcome before it can fully translate into the clinical context, the existence of strong opposition to the technology, political and legal barriers that have impeded its progression, and the role of healthcare reform in creating new social and economic priorities. In contrast to the technological imperative, a driving force seeking to implement the most recent scientific advances into medical practice, we refer to such translational obstacles as “technological impedance.” Rather than expending inordinate effort to preserve existing systems that continue to possess major hurdles, we advocate fostering interdisciplinary approaches in the development of new generation platforms and embracing disruptive innovations that create solutions to technological impedance and move us forward in healthcare delivery. Clin Trans Sci 2012; Volume 5: 422–427  相似文献   
79.
Cypermethrin, a class II pyrethroid pesticide, is used to control insects in the household and agricultural fields. Despite beneficial roles, its uncontrolled and repetitive applications lead to unintended effects in non-target organisms. Cypermethrin crosses the blood-brain barrier and induces neurotoxicity and motor deficits. Cypermethrin prolongs the opening of sodium channel, a major site of its action, leading to hyper-excitation of the central nervous system. In addition to sodium channel, cypermethrin modulates chloride, voltage-gated calcium and potassium channels, alters the activity of glutamate and acetylcholine receptors and adenosine triphosphatases and induces DNA damage and oxidative stress in the neuronal cells. Cypermethrin also modulates the level of neurotransmitters, including gamma-aminobutyric acid and dopamine. It is one of the most commonly used pesticides in neurotoxicology research not only because of its variable responses depending upon the doses, time and routes of exposure and strain, age, gender and species of animals used across multiple studies but also owing to its ability to induce the nigrostriatal dopaminergic neurodegeneration. This article describes the effect of acute, chronic, developmental and adulthood exposures to cypermethrin in experimental animals. The article sheds light on cypermethrin-induced changes in the central nervous system, including its contribution in the onset of specific features, which are associated with the nigrostriatal dopaminergic neurodegeneration. Resemblances and dissimilarities of cypermethrin-induced nigrostriatal dopaminergic neurodegeneration with sporadic and chemicals-induced disease models along with its advantages and pitfalls are also discussed.  相似文献   
80.
We present a rare case in which a young girl ingested a solution of a hair-removing soap. The ingestion resulted in profound hypokalemia and severe acidosis leading to flaccid paralysis, respiratory arrest and ventricular arrhythmias. Ultimately the patient made complete recovery. The soapwas found to contain barium sulfide. The degree of paralysis and acidosis appeared to be directly related to serum potassium levels.  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