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   60517篇
  免费   5262篇
  国内免费   4040篇
耳鼻咽喉   519篇
儿科学   803篇
妇产科学   1065篇
基础医学   7719篇
口腔科学   965篇
临床医学   7765篇
内科学   9463篇
皮肤病学   700篇
神经病学   3612篇
特种医学   2253篇
外国民族医学   52篇
外科学   6134篇
综合类   8071篇
现状与发展   19篇
一般理论   3篇
预防医学   4063篇
眼科学   1669篇
药学   6350篇
  62篇
中国医学   2997篇
肿瘤学   5535篇
  2024年   172篇
  2023年   928篇
  2022年   2365篇
  2021年   3104篇
  2020年   2236篇
  2019年   2112篇
  2018年   2226篇
  2017年   1873篇
  2016年   1876篇
  2015年   2681篇
  2014年   3323篇
  2013年   2807篇
  2012年   4418篇
  2011年   4893篇
  2010年   2952篇
  2009年   2249篇
  2008年   3111篇
  2007年   3150篇
  2006年   3149篇
  2005年   3125篇
  2004年   2130篇
  2003年   2066篇
  2002年   1781篇
  2001年   1249篇
  2000年   1315篇
  1999年   1410篇
  1998年   934篇
  1997年   881篇
  1996年   673篇
  1995年   616篇
  1994年   509篇
  1993年   331篇
  1992年   418篇
  1991年   369篇
  1990年   328篇
  1989年   284篇
  1988年   294篇
  1987年   240篇
  1986年   232篇
  1985年   182篇
  1984年   127篇
  1983年   98篇
  1982年   54篇
  1981年   52篇
  1980年   40篇
  1979年   97篇
  1978年   41篇
  1975年   40篇
  1974年   52篇
  1973年   30篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
121.
作者自行设计一种问卷对某企业职工进行社会心理调查。问卷由 A、B两表构成。A 表列出42个问题,包含可能影响该企业职工社会心理的三大类11项因素,要求从该企业中随机抽取的被调查者针对问题回答“是”或“否”。其后附开放式问题一个,被调查者可自由作答,以补封闭式提问的不足。B 表按心理投射机制设计,以解除被调查者的疑虑。测试结果表明,此问卷的信度和效度令人满意。  相似文献   
122.
Fifty-four kinds of crude drug derived from insects are listed in the "herbal" Jing-shi-zheng-lei-da-guang-ben-cao (1108 A.D.) edited during the Chinese Song dynasty (960-1280 A.D.). We considered each of them from the viewpoint of various herbals and have commented on them, the order being adhered to in most cases. We added our own findings of identification of insect crude drugs available on the market. The crude drugs emphasized are mantis egg case, wasp's nest, scarab larva, red cicada, snipe fly, horse fly, flying cockroach, Eupolyphaga, Chinese Cantharides and scarab beetle. Others are discussed to a lesser extent.  相似文献   
123.
B S Ma  N M Li  G R Wang 《中西医结合杂志》1989,9(10):583-6, 579
Based on the experience of the late Beijing traditional medicine professor Zhao Bingnan in treating acute infectious febrile disease and its complications, compound herbal drink composed of five kinds of shen. Six hundred cases of febrile disease with damage to Yin and reddened tongue syndrome and hypokalemia. Patients were randomly divided into groups I, II and control. The perspective study of treatment results and experiments were carried out. The results showed that group I and II who received the compound five-Shen herbal drink (CFSHD) showed good therapeutic effects, the rates of significant effectiveness were 65.5% and 73.1% respectively (P greater than 0.05). The total rates of effectiveness were 97.2% and 96.2% respectively. The rate of significant effectiveness of the control group was 11%, total rate of effectiveness was 43%. There was significant statistical difference between the control group and group I or II (P less than 0.001). Authors of present paper are the first to propose the "Reddened Tongue" to be the main diagnostic criterion of syndrome of "Damage both to the Qi and Yin". Laboratory examination of 344 cases of "Reddened Tongue" revealed that 317 cases with hypokalemia (blood potassium less than 3.5 mEq/L) were 92.15% of the entire group. The authors point out that most of the patients with "damage to both the Qi and Yin" besides hypokalemia can be also low in calcium, magnesium and trace elements. After treatment with CFSHD restoration of normal blood potassium was parallel with the improvement of the reddened tongue.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
124.
Fu SL  Ma ZW  Yin L  Iannotti C  Lu PH  Xu XM 《Neuroscience》2005,135(3):851-862
To determine whether neural precursor cells have region-specific growth properties, we compared the proliferation, mitogenicity, and differentiation of these cells isolated from the embryonic day 16 rat forebrain and spinal cord. Neural precursor cells isolated from both regions were cultured in growth medium supplemented with epidermal growth factor, basic fibroblast growth factor, or epidermal growth factor+basic fibroblast growth factor. Under all three conditions, both neural precursor cell populations proliferated for multiple passages. While spinal cord-derived neural precursor cells proliferated moderately faster in epidermal growth factor-enriched growth medium, brain-derived cells proliferated much faster in basic fibroblast growth factor-enriched growth medium. When exposed to both epidermal growth factor and basic fibroblast growth factor, the two neural precursor cell populations expanded and proliferated more rapidly than when exposed to a single factor, with brain-derived neural precursor cells expanding significantly faster than spinal cord-derived ones (P<0.0001). Differentiation studies showed that both neural precursor cell populations were multi-potent giving rise to neurons, astrocytes, and oligodendrocytes. However, neuronal differentiation from brain-derived neural precursor cells was greater than spinal cord-derived ones (11.95+/-5.00% vs 1.92+/-1.13%; passage 2). Further, the two neural precursor cell populations differentiated into a similar percentage of oligodendrocytes (brain: 8.66+/-5.85%; spinal cord: 7.69+/-3.91%; passage 2). Immunofluorescence and Western blot studies showed that neural precursor cells derived from both regions expressed receptors for basic fibroblast growth factor and epidermal growth factor. However, brain-derived neural precursor cells expressed higher levels of the two receptors than spinal cord-derived ones in growth medium containing epidermal growth factor+basic fibroblast growth factor. Thus, our results showed that neural precursor cells isolated from the two regions of the CNS have distinct properties and growth requirements. Identifying phenotypic differences between these neural precursor cell populations and their growth requirements should provide new insights into the development of cell therapies for region-specific neurological degenerative diseases.  相似文献   
125.
126.
The relationship between malignancy and histamine metabolism in the liver and the small intestine has been examined in sarcoma-bearing Wistar rats two weeks after subcutaneous implantation of a transplantable methylcholanthrene sarcoma Sa1828 and on the 3, 7 and 14th days after tumour extirpation. Two weeks after tumour implantation, the histamine level was increased by 100% and 50% in the liver and the small intestine, respectively. On the 3rd day after extirpation of the tumour the level of histamine had returned to the control values and remained unchanged during the next 10 days. Neither of the histamine catabolizing enzymes, diamine oxidase with a putrescine as a substrate or histamine methyltransferase were influenced by the existing tumour or by its extirpation except on the 14th day where a high increase in diamine oxidase activity was found. Some changes in the distribution of histamine metabolites suggest an involvement of an oxidative pathway of histamine catabolism as well as the aldehyde catabolizing enzymes in tumour development.  相似文献   
127.
Cantú syndrome (CS), characterized by hypertrichosis, distinctive facial features, and complex cardiovascular abnormalities, is caused by pathogenic variants in ABCC9 and KCNJ8 genes. These genes encode gain‐of‐function mutations in the regulatory (SUR2) and pore‐forming (Kir6.1) subunits of KATP channels, respectively, suggesting that channel‐blocking sulfonylureas could be a viable therapy. Here we report a neonate with CS, carrying a heterozygous ABCC9 variant (c.3347G>A, p.Arg1116His), born prematurely at 32 weeks gestation. Initial echocardiogram revealed a large patent ductus arteriosus (PDA), and high pulmonary pressures with enlarged right ventricle. He initially received surfactant and continuous positive airway pressure ventilation and was invasively ventilated for 4 weeks, until PDA ligation. After surgery, he still had ongoing bilevel positive airway pressure (BiPAP) requirement, but was subsequently weaned to nocturnal BiPAP. He was treated for pulmonary hypertension with Sildenafil, but failed to make further clinical improvement. A therapeutic glibenclamide trial was commenced in week 11 (initial dose of 0.05 mg–1 kg–1 day–1 in two divided doses). After 1 week of treatment, he began to tolerate time off BiPAP when awake, and edema improved. Glibenclamide was well tolerated, and the dose was slowly increased to 0.15 mg?1 kg?1day?1 over the next 12 weeks. Mild transient hypoglycemia was observed, but there was no cardiovascular dysfunction. Confirmation of therapeutic benefit will require studies of more CS patients but, based on this limited experience, consideration should be given to glibenclamide as CS therapy, although problems associated with prematurity, and complications of hypoglycemia, might limit outcome in critically ill neonates with CS.  相似文献   
128.
The results of brain MRI are presented in 22 patients with documented Nijmegen breakage syndrome (NBS), aged from 1 and 9/12 to 20 years. T1-, PD or FLAIR and T2-weighted SE/TSE images in three planes were obtained. Twenty-one patients showed microcephaly. Decreased size of frontal lobes and narrow frontal horns of the lateral ventricles was observed in all cases. In 6 patients agenesis of the posterior part of the corpus callosum was found as well as colpocephaly and temporal horn dilatation. In 2 patients callosal hypoplasia was accompanied by other anomalies: abnormal cerebrospinal fluid spaces. Sinusitis was present in all patients as a result of primary immunodeficiency. As in ataxia teleangiectasia and other breakage syndromes, NBS patients show inherited malignancy susceptibility and hypersensitivity to X and gamma radiation. Because of that computed tomography is contraindicated in these patients and MRI should be the method of choice in diagnostic imaging.  相似文献   
129.
β-hemolytic streptococcal infection in developing countries still causes thousands of cases of Rheumatic Fever (RF). Molecular mimicry between streptococcal M protein (strep M) and heart components has been proposed as the triggering factor leading to autoimmunity in individuals with genetic susceptibility, which is linked to different HLA-DR alleles in different populations. In our hands, RF was significantly associated to HLA-DR7/53. Previous work in our lab has shown that heart-infiltrating T cells that simultaneously recognize strep M and heart proteins. Further, such T cells predominantly recognized the 81-103 strep M5 epitope. In this work, we analysed the proliferative response of peripheral blood mononuclear cells of 99 RF patients and 40 normal controls. Eighty-nine of the RF patients were HLA-typed. As among heart-infiltrating T cells, the 81-103 strep M5 protein epitope is the most frequently recognized epitope among RF PBMC (35.4%), against a 7.5% frequency of proliferation among normal controls (p=0.0018, chi square). However, the 81-103 epitope was as frequently recognized by HLA-DR7,53 positive as by negative individuals (45.2% vs 54.8%, respectively). Taken together, the results suggest that the 81-103 strep M5 epitope may be the immunodominant epitope, “promiscuously” recognized by T cells in a genetically diverse population. The demonstration that molecular mimicry is targeted to a discrete immunodominant “promiscuous” epitope in strep M5 may allow the development of a safe anti-streptococcal synthetic vaccine devoid of such epitopes.  相似文献   
130.
Lyme disease refers to the multisymptomatic illness in humans which results from infection with the tick-borne spirochete Borrelia burgdorferi. The white-footed mouse is the major reservoir for B. burgdorferi and, upon infection, certain inbred mice develop symptoms similar to those reported in human disease. Sonicated preparations of washed spirochetes were found to have potent mitogenic activity when cultured with lymphocytes from naive C57BL/6, C3H/HeJ, or BALB/c mice. The activity of the B. burgdorferi sonicate was approximately fourfold greater than that of a similarly prepared Escherichia coli sonicate. Polymyxin B efficiently inhibited the mitogenic activity of the E. coli sonicate but only slightly inhibited that of the B. burgdorferi sonicate, suggesting that a lipid A-containing lipopolysaccharide was not responsible for the B. burgdorferi activity. Kinetic analysis indicated peak proliferation at 2 to 3 days of culturing, suggesting polyclonal activation. B- and T-lymphocyte depletion experiments indicated that the major cell type responding to the B. burgdorferi mitogen was the B lymphocyte. This mitogen stimulated murine B cells not only to proliferate but also to differentiate into antibody-secreting cells, as demonstrated by the production of immunoglobulin by stimulated splenocytes. Furthermore, the sonicated preparation stimulated the B-cell tumor line CH12.LX to secrete immunoglobulin in the absence of accessory cells. B. burgdorferi also stimulated interleukin-6 production in splenocyte cultures. The observation that B. burgdorferi can stimulate activation of and immunoglobulin production by normal B lymphocytes may directly reflect on the development of arthritis associated with persistent infection by this organism.  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