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   153388篇
  免费   10062篇
  国内免费   771篇
耳鼻咽喉   1408篇
儿科学   3902篇
妇产科学   2763篇
基础医学   20598篇
口腔科学   3457篇
临床医学   14736篇
内科学   32984篇
皮肤病学   2879篇
神经病学   14855篇
特种医学   6174篇
外国民族医学   6篇
外科学   23050篇
综合类   1905篇
现状与发展   2篇
一般理论   140篇
预防医学   11061篇
眼科学   3198篇
药学   10503篇
  2篇
中国医学   245篇
肿瘤学   10353篇
  2023年   818篇
  2022年   1238篇
  2021年   2830篇
  2020年   1958篇
  2019年   2818篇
  2018年   3427篇
  2017年   2664篇
  2016年   3048篇
  2015年   3517篇
  2014年   5041篇
  2013年   6804篇
  2012年   10527篇
  2011年   11156篇
  2010年   6356篇
  2009年   6048篇
  2008年   10207篇
  2007年   10886篇
  2006年   10354篇
  2005年   10610篇
  2004年   10010篇
  2003年   9501篇
  2002年   8924篇
  2001年   1501篇
  2000年   1129篇
  1999年   1601篇
  1998年   2108篇
  1997年   1651篇
  1996年   1422篇
  1995年   1292篇
  1994年   1143篇
  1993年   1115篇
  1992年   777篇
  1991年   783篇
  1990年   612篇
  1989年   599篇
  1988年   561篇
  1987年   577篇
  1986年   510篇
  1985年   536篇
  1984年   639篇
  1983年   567篇
  1982年   759篇
  1981年   704篇
  1980年   602篇
  1979年   368篇
  1978年   376篇
  1977年   403篇
  1976年   343篇
  1975年   295篇
  1974年   250篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
OBJECTIVE: Since the clinical picture of premenstrual dysphoric disorder (PMDD) in the Luteal phase of the menstrual cycle is characterized by extreme negative affect, we predicted and obtained a change in frontal cortical EEG alpha asymmetry, which has been shown to be an index of affect. METHOD: We observed two monthly cycles for five women diagnosed as having PMDD and one monthly cycle for five non-PMDD control subjects. RESULTS: Asymmetry percent scores for the five PMDD women, and for the five control subjects before and after the Luteal phase were typically within the normal non-depressed range, however the asymmetry scores for the PMDD group fell into the negative range during the Luteal period while the control subjects remained stable. DISCUSSION: We predicted alpha asymmetry scores would be affected by the luteal phase in PMDD cases. This hypothesis was clearly confirmed.  相似文献   
994.
BACKGROUND: Data on the efficacy of pimecrolimus cream 1% within the first days of treatment are scarce, as in previous studies, the first postbaseline assessment was performed only after 1 week. OBJECTIVE: We sought to investigate the onset of action of pimecrolimus cream 1% in infants with mild to very severe atopic eczema. METHODS: We used pimecrolimus cream 1% (n = 129) or vehicle cream (n = 66) administered in a double-blind manner for 4 weeks and then open-label pimecrolimus cream 1% for 12 weeks, with a 4-week follow-up period. RESULTS: Pimecrolimus cream 1% reduced the mean Eczema Area and Severity Index at 4 weeks by 71.5% compared with an increase of 19.4% with vehicle ( P < .001). The reduction in the Eczema Area and Severity Index with pimecrolimus cream 1% was significant at day 4 (38.5% vs 17.6% increase with vehicle). Significant improvements in caregivers' assessments of pruritus and sleep loss were observed with pimecrolimus cream 1% by day 2 ( P < .03) and day 3 ( P = .002), respectively, compared with vehicle. Responses to pimecrolimus cream 1% were sustained during the open-label phase, and pimecrolimus cream 1% was well tolerated. Symptoms of atopic eczema returned gradually after discontinuation. CONCLUSION: Pimecrolimus cream 1% was well tolerated and effective in patients with mild to very severe atopic eczema, with rapid onset of action and no disease rebound after discontinuation.  相似文献   
995.
Flagella ofLegionella pneumophila serogroup 1, strain Philadelphia (ATCC 33152), were isolated and used as antigen to detect antibodies by enzyme immunoassay (EIA) in sera of patients with significant titers againstLegionella as determined by the indirect immunofluorescence assay (IFA). Healthy blood donors served as a control group. Whereas the sera of blood donors were negative in both assays, sera of patients showed two patterns of reactivity. Sera with elevated titers againstLegionella pneumophilasero-group 1 orLegionella gormanii in IFA usually demonstrated high titers in EIA. However, high IFA titers againstLegionella bozemanii were associated with low titers in EIA. The data show that flagella protein ofLegionella pneumophila serogroup 1 strain Philadelphia is of limited value for the detection of antibodies againstLegionella other thanLegionella pneumophila serogroup 1, although in vitro studies revealed genus-specific epitopes. This might be due to unpredictable variabilities in the expression of flagella in vivo.  相似文献   
996.
The extent to which the relationship between body fat and blood pressure either differs by sex or explains sex differences in blood pressure is examined. Estimates of the relationship of blood pressure to several measures of adiposity in men and women were obtained from a systematic review of the literature and tests of whether these relationships differ by sex were performed. Analysis of covariance (controlling for age and race) was used for both casual and ambulatory blood pressure in the Cornell Worksite Blood Pressure Study (N = 276). In general, most adiposity measures were significantly related to casual and ambulatory blood pressure in men and women. Subscapular skinfold thickness and body mass index exhibited the strongest associations. The vast majority of adiposity/blood pressure associations were not significantly different for men and women. Finally, sex differences in adiposity did not account for much of the sex difference observed in blood pressure. © 1995 Wiley-Liss, Inc.  相似文献   
997.
Growing evidence suggests that G‐proteins may be involved in pathogenesis and treatment of affective disorders. Several studies have reported altered levels and/or activities of stimulatory G‐proteins in depression. The aim of this study was to investigate whether a polymorphism in the stimulatory α subunit of G‐proteins (T/C point mutation in exon 5; ATT → ATC at codon 131) is associated with major depression or response to antidepressant treatment. Therefore, we performed a case‐control association study with 212 depressive patients and 137 healthy, unrelated controls. There was no evidence for an association between the investigated polymorphism in the Gαs gene and major depression, as well as to treatment response. The results of our study are in concordance with recently published findings which do not support the hypothesis that the gene for the stimulatory α subunit of G‐proteins is a major susceptibility factor in the pathophysiology of major depression. © 2002 Wiley‐Liss, Inc.  相似文献   
998.
DEC1, also known as SHARP-2 or Stra13, is an important molecule in embryonic differentiation and has recently been identified to be strongly inducible by hypoxia. Its distribution in normal human tissues and most tumour types is unknown. In the present study, a polyclonal antiserum to a 10-amino acid peptide from DEC1 has been raised. Using this antiserum, DEC1 was shown to be widely expressed in most normal human tissues, but usually only in a proportion of cells and typically with a nuclear localization. In tumours, expression was either augmented (the commonest pattern) or occasionally decreased. Similarly, in most normal tissues, low or absent expression was observed in endothelial cells, whereas in many tumour samples endothelium was usually strongly positive. In tumours, there was a striking pattern of staining seen in connection with areas of necrosis, with absence of DEC1 expression within a zone of morphologically viable cells immediately adjacent to the necrotic zone. This suggests that while DEC1 may be up-regulated by hypoxia in cancer, in more extreme hypoxia it may have a role in cell death. Its interrelationship with other hypoxically regulated molecules, such as the hypoxia-inducible factors or carbonic anhydrase IX, and differentiation of tumours now requires further investigation.  相似文献   
999.
1000.
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