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   44006篇
  免费   2278篇
  国内免费   145篇
耳鼻咽喉   598篇
儿科学   2830篇
妇产科学   757篇
基础医学   5330篇
口腔科学   1172篇
临床医学   3105篇
内科学   7876篇
皮肤病学   1205篇
神经病学   2627篇
特种医学   1253篇
外科学   6520篇
综合类   1431篇
一般理论   21篇
预防医学   2367篇
眼科学   1543篇
药学   4465篇
  1篇
中国医学   373篇
肿瘤学   2955篇
  2023年   353篇
  2022年   1062篇
  2021年   1747篇
  2020年   959篇
  2019年   1070篇
  2018年   1488篇
  2017年   1080篇
  2016年   1422篇
  2015年   1459篇
  2014年   2119篇
  2013年   2396篇
  2012年   3404篇
  2011年   3333篇
  2010年   1996篇
  2009年   1563篇
  2008年   2280篇
  2007年   2277篇
  2006年   2117篇
  2005年   1838篇
  2004年   1744篇
  2003年   1480篇
  2002年   1253篇
  2001年   879篇
  2000年   812篇
  1999年   680篇
  1998年   310篇
  1997年   244篇
  1996年   242篇
  1995年   204篇
  1994年   172篇
  1993年   160篇
  1992年   403篇
  1991年   369篇
  1990年   390篇
  1989年   387篇
  1988年   327篇
  1987年   260篇
  1986年   262篇
  1985年   256篇
  1984年   200篇
  1983年   160篇
  1982年   79篇
  1981年   88篇
  1980年   87篇
  1979年   131篇
  1978年   83篇
  1977年   98篇
  1976年   73篇
  1973年   80篇
  1971年   72篇
排序方式: 共有10000条查询结果,搜索用时 21 毫秒
31.
Estimation of T and B lymphocytes was done in 50 patients of enteric fever, 50 duration matched non enteric fever patients and 50 normal healthy individuals. The difference in both early and late rosette forming T lymphocytes was found to be statistically significant in enteric versus non-enteric patients. Significant difference was also observed in enteric versus normal individuals in case of late rosette forming T lymphocytes.  相似文献   
32.
33.
Even though a variety of adverse effects caused by sweeteners, flavorings, and dyes in susceptible individuals have been reported, there is no good single reference with information about these substances in pediatric antimicrobials. Data on sweeteners, flavorings, and dyes in 91 antimicrobial preparations were collected. Sucrose was present in 74 (85%) of 87 preparations, followed by saccharin in 30 (34%) preparations. Mannitol, lactose, and sorbitol were each present in 7 preparations. None of the preparations were free of sweeteners. Thirty-four (37%) of 91 preparations did not specify the flavoring content. While cherry was the most common flavoring used, there were 25 other flavorings. Thirteen different dyes and coloring agents were used in these antimicrobials. Red dye no. 40 was present in 45% of preparations. Tables detailing sweeteners, flavorings, and dyes in different groups of antimicrobials (amoxicillin, ampicillin, cephalosporins, erythromycin, penicillins, sulfonamides, and others) and adverse effects reported with these inert ingredients are presented. These tables should be helpful to physicians in selecting an antimicrobial containing a different sweetener and/or dye when an adverse reaction occurs.  相似文献   
34.
The genotoxic effect of an extract of smoke-dried meat was assayed by employing in vivo sperm head shape abnormality. A significant dose responsive mutagenic effect was observed using the sperm head shape abnormality test. The result indicates that higher doses i.e., 100 and 200 mg/kg body wt. of smoke meat extract, significantly induced sperm head shape abnormality as compared to lower doses i.e., 20 mg/kg body wt. and control.  相似文献   
35.
The mitogenic, chemotactic, and synthetic responses of rat periodontal ligament (PDL) fibroblastic cells to epidermal growth factor (EGF), transforming growth factor-beta (TGF-beta), recombinant human platelet-derived growth factor (rhPDGF)-AB, rhPDGF-BB, natural (n) PDGF-AB, and insulin-like growth factor-I (IGF-I) were examined in vitro using PDL cells obtained from the coagulum of healing tooth sockets. PDGFs and IGF-I have potent and comparable mitogenic effects on PDL fibroblastic cells. The maximum mitogenic effect of PDGFs was observed at the concentration of 10 ng/ml, whereas that of IGF-I was seen at concentrations higher than 100 ng/ml. In contrast, EGF induced moderate, and TGF-beta inhibitory mitogenic responses. The combination of rhPDGF-AB with either EGF or TGF-beta demonstrated comparable mitogenic potency, equivalent to the level of PDGF alone regardless of the mitogenic effect of other growth factors. The combination of rhPDGF-AB and IGF-I, however, showed a synergistic effect revealing the highest mitogenic effect among all individual growth factors as well as any combinations of the growth factors tested. Similarly, PDL fibroblastic cells demonstrated strong chemotactic responses to both IGF-I and PDGFs. The maximum effect was observed by IGF-I at concentrations higher than 10 ng/ml, followed by rhPDGF-BB at 0.1 ng/ml, rhPDGF-AB and nPDGF at concentrations ranging from 0.1 to 1 ng/ml. TGF-beta revealed no, and EGF slightly increased, chemotactic effects. IGF-I slightly enhanced the synthesis of total protein, whereas other factors had no significant effect. However, both rhPDGF-AB and TGF-beta stimulated collagen synthesis. On the other hand, IGF-I showed no effect on collagen synthesis, while EGF suppressed collagen synthesis. These findings suggest that rhPDGF-BB and IGF-I stimulate proliferation and chemotaxis of PDL fibroblastic cells. In addition, the combination of these growth factors further increases the mitogenic effect. rhPDGF-AB also stimulates collagen synthesis by PDL fibroblastic cells. Thus, rhPDGF-BB and IGF-I may have important roles in promotion of PDL healing, and consequently, may be useful for clinical application in periodontal regenerative procedures.  相似文献   
36.
Chemotherapy in recurrent and advanced cervical cancer.   总被引:2,自引:0,他引:2  
Twenty-five patients, ranging from 21 to 61 years of age (median = 45 years), with histologically proven recurrent and advanced cervical cancer were treated with chemotherapy using a combination of bleomycin, ifosfamide, and cis-platinum (BIP). Twenty-one patients were evaluable for response. Ninety percent of patients achieved a subjective response. An objective response was noted in 14 of 21 (66.6%) patients: complete in 4 (19%) and partial in 10 (47.6%). Side effects were mainly nausea/vomiting, alopecia, myelosuppression, reversible encephalopathy, and impaired renal function. One patient died from the toxic effects of chemotherapy. These results indicate that BIP is an active combination in recurrent cervical cancer with acceptable toxicity.  相似文献   
37.
38.
Complete dislocation of the lens is a rare feature of Marfan's Syndrome. We observed four cases of bilateral complete posterior dislocation of the lens in established cases of Marfan's Syndrome over a one year period. An ophthalmologist may encounter infrequently, unilateral posterior dislocation in one eye and ectopia lentis in the other, but bilateral spontaneous posterior dislocation is rare. All our cases had associated vitreous degeneration with vitreous herniating into the anterior chamber. The pathogenesis of complete posterior dislocation in Marfan's Syndrome is discussed.  相似文献   
39.
A cell line from Wilms' tumour with deletion in short arm of chromosome II   总被引:1,自引:0,他引:1  
A cell line (T3/73) from a Wilms' tumour has been established from a 9 month-old boy with aniridia. The tumour was removed in 1973. On histological examination a diagnosis of Wilms' tumour was made which showed undifferentiated areas, marked tubule formation and abundant striped muscle fibres. The tumour cells, which are fusiform, grew rapidly in culture without the addition of growth factors, and have undergone over 100 passages. Approximately 95% and 5% were positive for desmin and cytokeratin, respectively. The cell doubling time was 28 hr. Cytogenetic studies revealed a karyotype of 46,XY,del(11) (p12::p14). Although the cells stained very intensely with a monoclonal antibody that detects oncogene ras p 21 antigen, Southern blot analysis using c-Ha-ras as a probe failed to reveal an obvious deletion or amplification of either Ha-ras allele.  相似文献   
40.
Eight healthy, young adult males underwent three separate, 10-min 70 degrees head-up tilts (HUT) over a period of nine days, in order to assess the intra- and inter-individual variability of cardiovascular and plasma norepinephrine (NE) responses to the manoeuvre. Cardiovascular parameters and plasma NE were measured in the basal state and at 2-min intervals during the HUT. The results indicate that: (1) the intra-individual variability is a smaller component of the total variability of both cardiovascular and plasma NE responses to HUT; (2) the variability in cardiovascular parameters is smaller than that in plasma NE levels, both basal and in response to postural stress; (3) there does not appear to be any difference in variability when expressed either as the maximal or the mean response to HUT; and (4) there does not appear to be an increase in the variability of the measured parameters over the duration of the HUT.  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