全文获取类型
收费全文 | 46077篇 |
免费 | 3165篇 |
国内免费 | 181篇 |
专业分类
耳鼻咽喉 | 284篇 |
儿科学 | 1463篇 |
妇产科学 | 1002篇 |
基础医学 | 5564篇 |
口腔科学 | 875篇 |
临床医学 | 4722篇 |
内科学 | 10236篇 |
皮肤病学 | 868篇 |
神经病学 | 4207篇 |
特种医学 | 1481篇 |
外科学 | 7190篇 |
综合类 | 659篇 |
一般理论 | 60篇 |
预防医学 | 3374篇 |
眼科学 | 1070篇 |
药学 | 3182篇 |
中国医学 | 51篇 |
肿瘤学 | 3135篇 |
出版年
2023年 | 147篇 |
2022年 | 313篇 |
2021年 | 718篇 |
2020年 | 415篇 |
2019年 | 715篇 |
2018年 | 875篇 |
2017年 | 678篇 |
2016年 | 721篇 |
2015年 | 901篇 |
2014年 | 1263篇 |
2013年 | 1882篇 |
2012年 | 2917篇 |
2011年 | 3095篇 |
2010年 | 1767篇 |
2009年 | 1604篇 |
2008年 | 2864篇 |
2007年 | 3082篇 |
2006年 | 3033篇 |
2005年 | 3141篇 |
2004年 | 2990篇 |
2003年 | 2795篇 |
2002年 | 2724篇 |
2001年 | 634篇 |
2000年 | 525篇 |
1999年 | 656篇 |
1998年 | 699篇 |
1997年 | 519篇 |
1996年 | 469篇 |
1995年 | 401篇 |
1994年 | 348篇 |
1993年 | 373篇 |
1992年 | 424篇 |
1991年 | 394篇 |
1990年 | 376篇 |
1989年 | 353篇 |
1988年 | 317篇 |
1987年 | 254篇 |
1986年 | 268篇 |
1985年 | 276篇 |
1984年 | 347篇 |
1983年 | 284篇 |
1982年 | 332篇 |
1981年 | 302篇 |
1980年 | 295篇 |
1979年 | 188篇 |
1978年 | 166篇 |
1977年 | 175篇 |
1976年 | 149篇 |
1974年 | 138篇 |
1973年 | 122篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
A new range of stand magnifiers has been released by the COIL company in the United Kingdom. Examination of these magnifiers reveals that they fail to deliver the rated magnifications labelled prominently on the appliances, as a result of the manufacturer's conformance with the requirements of the German DIN standard and the use of back vertex power (F'v) rather than equivalent dioptric power (Fm) of the magnifier. In this study we provide information on the optometric parameters of these new stand magnifiers that will assist the more accurate specification of improvements in vision expected from their use. 相似文献
23.
Tauseef Ahmed Alan Yagoda Howard I. Scher Cora Sternberg Robin C. Watson 《Investigational new drugs》1986,4(2):171-174
Summary Deaza-aminopterin is a folate analog which is transported more rapidly than methotrexate into cells and appears to be more active than methotrexate against human and animal tumor in vitro. Fifteen patients with advanced urothelial tract cancer were given deaza-aminopterin 30–37.5 mg/m2 IV QW. In responding patients drug was given QOW after 4–6 consecutive doses. Doses were escalated or de-escalated by 7.5 mg/m2 depending on toxicity. Twelve patients had received prior chemotherapy which included methotrexate in nine. Three patients achieved a partial remission lasting 1, 3, and 3 months respectively: all responders had previously failed methotrexate after an initial response to a methotrexate containing regimen. None of the six patients who were methotrexate naive responded to deaza-aminopterin; 3 subsequently received methotrexate without response. Mild mucositis was universal and in 5 was severe. Six patients had an increase in liver transaminases probably secondary to anti-folate hepatotoxicity. Other toxicities included diarrhea, nausea, skin rash and fever. Further studies are needed to define the precise efficacy of deaza-aminopterin in patients with urothelial tract cancers. 相似文献
24.
Loss of basal forebrain P75(NTR) immunoreactivity in subjects with mild cognitive impairment and Alzheimer's disease. 总被引:13,自引:0,他引:13
Elliott J Mufson Shuang Y Ma John Dills Elizabeth J Cochran Sue Leurgans Joanne Wuu David A Bennett Syed Jaffar Michelle L Gilmor Alan I Levey Jeffrey H Kordower 《The Journal of comparative neurology》2002,443(2):136-153
The long-held belief that degeneration of the cholinergic basal forebrain was central to Alzheimer's disease (AD) pathogenesis and occurred early in the disease process has been questioned recently. In this regard, changes in some cholinergic basal forebrain (CBF) markers (e.g. the high affinity trkA receptor) but not others (e.g., cortical choline acetyltransferase [ChAT] activity, the number of ChAT and vesicular acetylcholine transporter-immunoreactive neurons) suggest specific phenotypic changes, but not frank neuronal degeneration, early in the disease process. The present study examined the expression of the low affinity p75 neurotrophin receptor (p75(NTR)), an excellent marker of CBF neurons, in postmortem tissue derived from clinically well-characterized individuals who have been classified as having no cognitive impairment (NCI), mild cognitive impairment (MCI), and mild AD. Relative to NCI individuals, a significant and similar reduction in the number of nucleus basalis p75(NTR)-immunoreactive neurons was seen in individuals with MCI (38%) and mild AD (43%). The number of p75(NTR)-immunoreactive nucleus basalis neurons was significantly correlated with performance on the Mini-Mental State Exam, a Global Cognitive Test score, as well as some individual tests of working memory and attention. These data, together with previous reports, support the concept that phenotypic changes, but not frank neuronal degeneration, occur early in cognitive decline. Although there was no difference in p75(NTR) CBF cell reduction between MCI and AD, it remains to be determined whether these findings lend support to the hypothesis that MCI is a prodromal stage of AD. 相似文献
25.
26.
27.
Joseph M. Becker M.D. Peter H. Arger Alan J. Wein A. Richard Kendall 《Urologic radiology》1983,5(1):127-129
A 35-year-old man discovered a 1-cm nodule at the upper pole of the left testicle after blunt focal trauma. While the pain, tenderness, and location suggested hematoma or appendiceal torsion, the demonstration by ultrasound of the size, cystic nature, and extraparenchymal location was consistent with the rarely documented cyst of the tunica albuginea. 相似文献
28.
Isolated ultrafiltration, hemodialysis & peritoneal dialysis (Tx) were recently used in the treatment of intractable heart failure (HF). We examined the relation between the response of HF to Tx and the residual kidney functions. Tx was carried out in 17 patients (Pts) with HF who did not respond to aggressive medical treatment. Ten Pts (R) responded to Tx and 7 Pts (N) did not. Serum urea nitrogen (UN), creatinine (Cr), uric acid (UA), sodium (Na), potassium (K), and chloride (Cl) concentrations on admission and before Tx were not different between R and N. Urine UN, Cr, Na, K, and Cl on admission and before Tx were also not significantly different. Fractional sodium excretions (FENa), renal failure indices (RFI), and urine/plasma Cr ratios (U/P Cr) on admission were 2.0 +/- 1.6, 2.7 +/- 2.2, and 30.5 +/- 20.0 in R and 5.9 +/- 4.2, 8.2 +/- 6.0 and 11.5 +/- 3.8 in N. They were significantly different (p less than 0.05). However, these did not differ before and after Tx. These data show that FENa, RFI and U/P Cr might be useful indices in predicting the responsiveness of intractable HF to Tx. 相似文献
29.
30.
Single-cause Attribution 总被引:3,自引:1,他引:2
Alan Leviton 《Developmental medicine and child neurology》1987,29(6):805-807