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   19269篇
  免费   1157篇
  国内免费   138篇
耳鼻咽喉   162篇
儿科学   433篇
妇产科学   383篇
基础医学   2229篇
口腔科学   787篇
临床医学   1872篇
内科学   4146篇
皮肤病学   404篇
神经病学   1180篇
特种医学   437篇
外国民族医学   5篇
外科学   2514篇
综合类   492篇
一般理论   14篇
预防医学   1592篇
眼科学   753篇
药学   1823篇
中国医学   216篇
肿瘤学   1122篇
  2024年   31篇
  2023年   251篇
  2022年   703篇
  2021年   1093篇
  2020年   730篇
  2019年   882篇
  2018年   1050篇
  2017年   742篇
  2016年   800篇
  2015年   808篇
  2014年   1077篇
  2013年   1244篇
  2012年   1705篇
  2011年   1732篇
  2010年   1025篇
  2009年   788篇
  2008年   1144篇
  2007年   1019篇
  2006年   856篇
  2005年   722篇
  2004年   570篇
  2003年   468篇
  2002年   395篇
  2001年   54篇
  2000年   68篇
  1999年   67篇
  1998年   52篇
  1997年   48篇
  1996年   45篇
  1995年   38篇
  1994年   21篇
  1993年   33篇
  1992年   25篇
  1991年   19篇
  1990年   23篇
  1989年   22篇
  1988年   17篇
  1987年   10篇
  1986年   14篇
  1985年   12篇
  1984年   20篇
  1983年   17篇
  1982年   16篇
  1981年   11篇
  1980年   12篇
  1979年   14篇
  1978年   10篇
  1976年   10篇
  1974年   10篇
  1973年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
We have previously reported that XK469 (2-[4-(7-chloro-2-quinoxalinyloxyphenoxy]-propionic acid) enhances topo IIalpha expression in WSU-WM cells in vitro [E. Mensah-Osman et al., Mol. Cancer Ther., 1: 1321-1326, 2002]. To test the hypothesis that XK469-induced expression of topo IIalpha sensitizes WSU-WM cells to the topo IIalpha inhibitor etoposide (VP-16), we investigated the antitumor effects of XK469 and VP-16 in vivo, using the WSU-WM SCID xenograft model. Individual dosages of XK469 at 20-60 mg/kg/injection i.v. for a maximum-tolerated dose of 240 mg/kg were achievable in SCID mice. Simultaneous administration of a subtherapeutic dose of XK469 (20 mg/kg) and VP-16 at its maximum-tolerated dose of 15 mg/kg proved to be highly toxic and lethal. However, daily sequential treatment of XK469 given i.v. via tail vein at 20 mg/kg for a total of 120 mg/kg, followed 7 h later by VP-16 i.p. at 15 mg/kg for a total of 90 mg/kg, had no significant toxicity in SCID mice. The sequential treatment was associated with enhanced antitumor activity. Tumor growth inhibition T/C, tumor growth delay T-C, and log(10) kill for XK469 alone were 61%, 3 days and 0.46; VP-16 alone 6%, 12 days and 1.83, respectively; whereas the sequential administration of both agents gave a T/C value of 0%, T-C value of 23 days and a log(10) kill of 3.5. On the basis of these animal results, we conclude that the sequential treatment of WSU-WM tumors with XK469 and VP-16 was highly active. The study supports our in vitro observation that XK469 potentiates VP-16 activity. The sequential use of both agents resulted in clinically significant antitumor activity in the WM model.  相似文献   
112.
This article tests the hypothesis that anthropometrical outcomes in preschool children are a function of complex interaction between food, nutrition, health, and other physical environmental conditions within which children live and grow. A system of simultaneous equations is used to test the above hypothesis using data from an Ethiopian highland community. The results show that a child's nutritional and health status are jointly determined by dietary intake, well-being of the mother as the primary caregiver, and the state of the physical environment for agricultural production and healthy living. Among other factors, children were found to be in better health with an increase in the number of cows in their households' livestock herds. The revealed interrelatedness and complexities of cause and effect clearly dictate the need for a multi- or transdisciplinary approach to research and development addressing health, nutrition, sanitation, agricultural production practices, among other factors for alleviating the nutritional and health problems of children and rural households.  相似文献   
113.
There have been conflicting reports as to whether olanzapine produces lower occupancy of striatal dopamine D(2)/D(3) receptor than typical antipsychotic drugs and preferential occupancy of extrastriatal dopamine D(2)/D(3) receptors. We performed [(18)F] fallypride PET studies in six schizophrenic subjects treated with olanzapine and six schizophrenic subjects treated with haloperidol to examine the occupancy of striatal and extrastriatal dopamine receptors by these antipsychotic drugs. [(18)F] setoperone PET studies were performed in seven olanzapine-treated subjects to determine 5-HT(2A) receptor occupancy. Occupancy of dopamine D(2)/D(3) receptors by olanzapine was not significantly different from that seen with haloperidol in the putamen, ventral striatum, medial thalamus, amygdala, or temporal cortex, that is, 67.5-78.2% occupancy; olanzapine produced no preferential occupancy of dopamine D(2)/D(3) receptors in the ventral striatum, medial thalamus, amygdala, or temporal cortex. There was, however, significantly lower occupancy of substantia nigra/VTA dopamine D(2)/D(3) receptors in olanzapine-treated compared to haloperidol-treated subjects, that is, 40.2 vs 59.3% (p=0.0014, corrected for multiple comparisons); in olanzapine-treated subjects, the substantia nigra/VTA was the only region with significantly lower dopamine D(2)/D(3) receptor occupancy than the putamen, that is, 40.2 vs 69.2% (p<0.001, corrected for multiple comparison). Occupancy of 5-HT(2A) receptors was 85-93% in the olanzapine- treated subjects. The results of this study demonstrated that olanzapine does not produce preferential occupancy of extrastriatal dopamine D(2)/D(3) receptors but does spare substantia nigra/VTA receptors. Sparing of substantia nigra/VTA dopamine D(2)/D(3) receptor occupancy may contribute to the low incidence of extrapyramidal side effects in olanzapine-treated patients.  相似文献   
114.
PURPOSE: Aberrant promoter hypermethylation of several known or putative tumor suppressor genes occurs frequently during the pathogenesis of prostate cancers and is a promising marker for cancer detection. We sought to develop a test for prostate cancer based on a quantitative methylation-specific polymerase chain reaction (QMSP) of multiple genes in urine sediment DNA. PATIENTS AND METHODS: We tested urine sediment DNA for aberrant methylation of nine gene promoters (p16INK4a, p14(ARF), MGMT, GSTP1, RARbeta2, CDH1 [E-cadherin], TIMP3, Rassf1A, and APC) from 52 patients with prostate cancer and 21 matched primary tumors by quantitative fluorogenic real-time polymerase chain reaction. We also analyzed urine sediments from 91 age-matched individuals without any history of genitourinary malignancy as controls. RESULTS: Promoter hypermethylation of at least one of the genes studied was detected in urine samples from all 52 prostate cancer patients. Urine samples from the 91 controls without evidence of genitourinary cancer revealed no methylation of the p16, ARF, MGMT, and GSTP1 gene promoters, whereas methylation of RARbeta2, TIMP3, CDH1, Rassf1A, and APC was detected at low levels. CONCLUSION: Overall, methylation found in urine samples matched the methylation status in the primary tumor. A combination of only four genes (p16, ARF, MGMT, and GSTP1) would theoretically allow us to detect 87% of prostate cancers with 100% specificity. Our data support further development of the noninvasive QMSP assay in urine DNA for early detection and surveillance of prostate cancer.  相似文献   
115.
Traditional Persian medicine (TPM) proposes a different viewpoint to the chronic diseases. Diagnosis and implemented treatment are based on individual differences among patients. Constipation or Ea''teghal-e-batn is a condition in which the patient develops difficult or painful defecation. Based on TPM concepts, the first digestion step starts from halq (oral cavity), and ends via defecation from the maq''ad (anus). Avicenna believed that four faculties, ha''zemeh (digestive), ja''zebeh (absorptive), ma''sekeh (retentive) and da''fe''eh (propulsive), are involved in the process of digestion and absorption of the ingested food and expelling the waste materials. The bowel movement and appearance of the stool is a measure for evaluating the gastrointestinal healthy function. Defecation should be with no pain and fecal material should have no burning and acuity. Low food intake or foods with dry temperament, dryness of gastrointestinal tract, diaphoresis and heavy exercise as well as intestine sensory loss were discussed as main causes of constipation. Management of constipation in TPM includes dietary schemes, oil massages and subsequently simple herbal medicines. According to TPM theories, the first step in treating a disease is the elimination of disease causes (asbab e-maraz) and also providing the causes of health (asbab-e-sehhat). Health care providers should know the proper condition which the herbal medicines should be administered in and be able to guide the patients about the benefits and hazards of herbal remedies, commonly used in their living origin.  相似文献   
116.
117.
Pathogenic mutations in the FARSB gene are associated with neurodevelopmental disorder involving the brain, liver, and lungs. We report genetic analysis of a family including two affected members with this disorder, which revealed a homozygous pathogenic missense variant, FARSB: NM_005687.4:c.853G > A:p.E285K in both affected patients. The parents were heterozygous for this variant.  相似文献   
118.
119.
120.
Purpose:The proportion of axial length (AL) occupied by vitreous chamber depth (VCD), or VCD:AL, consistently correlates to ocular biometry in the general population. Relation of VCD:AL to ocular biometry in high myopia is not known. The purpose of this study is to evaluate the relation of VCD and VCD:AL to ocular biometry of highly myopic eyes.Methods:This was a cross-sectional retrospective study of records of 214 myopic eyes (<−1 D SE, aged 20–40 years) attending the refractive surgery services. High axial myopia was defined as AL >26.5 mm. Eyes with posterior staphyloma and myopic maculopathy were excluded. Records were assessed for measurements of AL, central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), white to white diameter (WTW), and vitreous chamber depth (VCD). Groups were formed based on increasing AL, while the sum of CCT, ACD, and LT was recorded as anterior segment depth (AS). The main outcome measure was the correlation of VCD and VCD:AL to ocular biometry. A comparison was also performed based on of degree of axial myopia.Results:Mean age of the patients was 27.0 ± 5.2 years. VCD showed a very strong correlation with AL (R = 0.98, P < 0.001) but did not correlate to any anterior parameter. VCD:AL showed moderate negative relation with AS (R = −0.43, P < 0.001) and ACD (R = −0.3, P < 0.001), while it had a weakly negative relation with LT (R = −0.18, P = 0.006). VCD:AL showed strong negative relation (R > ~0.7) with AS in all individual groups of AL. Among anterior parameters, WTW showed the most consistent relation with ocular biometry.Conclusion:VCD:AL is a better correlate of ocular biometry in high myopia as compared to VCD. However, the correlation is weaker than that noted by previous studies done on the general population. Longitudinal studies of VCD:AL in the younger age group is recommended.  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