全文获取类型
收费全文 | 80418篇 |
免费 | 6133篇 |
国内免费 | 255篇 |
专业分类
耳鼻咽喉 | 913篇 |
儿科学 | 2087篇 |
妇产科学 | 1112篇 |
基础医学 | 10952篇 |
口腔科学 | 859篇 |
临床医学 | 8551篇 |
内科学 | 17289篇 |
皮肤病学 | 892篇 |
神经病学 | 7777篇 |
特种医学 | 3084篇 |
外科学 | 13067篇 |
综合类 | 922篇 |
一般理论 | 94篇 |
预防医学 | 6033篇 |
眼科学 | 1964篇 |
药学 | 5438篇 |
中国医学 | 94篇 |
肿瘤学 | 5678篇 |
出版年
2023年 | 669篇 |
2022年 | 1043篇 |
2021年 | 2423篇 |
2020年 | 1364篇 |
2019年 | 2216篇 |
2018年 | 2539篇 |
2017年 | 1810篇 |
2016年 | 1902篇 |
2015年 | 2225篇 |
2014年 | 3232篇 |
2013年 | 4100篇 |
2012年 | 6555篇 |
2011年 | 6775篇 |
2010年 | 3705篇 |
2009年 | 3258篇 |
2008年 | 5429篇 |
2007年 | 5651篇 |
2006年 | 5216篇 |
2005年 | 5169篇 |
2004年 | 4684篇 |
2003年 | 4296篇 |
2002年 | 3892篇 |
2001年 | 633篇 |
2000年 | 437篇 |
1999年 | 608篇 |
1998年 | 800篇 |
1997年 | 601篇 |
1996年 | 486篇 |
1995年 | 438篇 |
1994年 | 408篇 |
1993年 | 407篇 |
1992年 | 284篇 |
1991年 | 231篇 |
1990年 | 201篇 |
1989年 | 197篇 |
1988年 | 187篇 |
1987年 | 140篇 |
1986年 | 156篇 |
1985年 | 161篇 |
1984年 | 196篇 |
1983年 | 172篇 |
1982年 | 245篇 |
1981年 | 245篇 |
1980年 | 175篇 |
1979年 | 109篇 |
1978年 | 136篇 |
1977年 | 114篇 |
1976年 | 81篇 |
1975年 | 71篇 |
1974年 | 63篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
Vascular malformation (AVM) in the gastrointestinal tract is an uncommon, but not rare, cause of bleeding and iron deficiency anemia, especially in an aging population. While endoscopic coagulative therapy is the method of choice for controlling bleeding, a substantial number of cases require additional therapy. Adjunctive or even primary phamacotherapy may be indicated in recurrent bleeding. However, there is little evidence-based proof of efficacy for any agent. The bulk of support is derived from anecdotal reports or case series. The present review compares the outcome of AVM after no intervention, coagulative therapy or focus on pharmacological agents. Most of the literature encompasses two common AVMs, angiodysplasia and hereditary hemorrhagic telangiectasia. Similarly, the bulk of information evaluates two therapies, hormones (estrogen and progesterone) and the somatostatin analogue octreotide. Of these, the former is the only therapy evaluated in randomized trials, and the results are conflicting without clear guidelines. The latter therapy has been reported only as case reports and case series without prospective trials. In addition, other anecdotally used medications are discussed. 相似文献
42.
43.
Frank G. Shellock Jerrold H. Mink Andrew L. Deutsch James Fox Todd Molnar Ronald Kvitne Richard Ferkel 《Journal of magnetic resonance imaging : JMRI》1994,4(4):590-594
The effect of a newly developed patellar realignment brace was evaluated in 21 patellofemoral joints (19 patients) with patellar subluxation (13 joints with lateral subluxation and eight with medial subluxation) by using active-movement, loaded kinematic magnetic resonance (MR) imaging. Sixteen patellofemoral joints (76%) demonstrated a qualitative correction of or improvement in patellar subluxation (ie, centralization of the patella or a decrease in the displacement of the patella) after application of the brace. Four of the five “failures” occurred in patellofemoral joints that had patella alta and/or dysplastic bone anatomy. These results indicate that the patellar realignment brace was able to counteract patellar subluxation in the majority of patellofemoral joints studied, as shown by active-movement, loaded kinematic MR imaging. This brace appears to be useful for conservative treatment of patients with patellofemoral joint pain secondary to patellar malalignment and maltracking. 相似文献
44.
45.
Veronique Braud E. Yvonne Jones Andrew McMichael 《European journal of immunology》1997,27(5):1164-1169
Human histocompatibility leukocyte antigen E (HLA-E) and mouse major histocompatibility complex (MHC) class Ib antigen, Qa-1, share the same substitutions at two normally conserved positions 143 and 147, which are likely to affect binding of the C terminus of peptides. Qa-1 is able to bind a peptide derived from the leader sequence of H-2 D and H-2 L molecules. We developed a peptide binding assay in vitro to compare the binding specificity of HLA-E with the mouse MHC class Ib molecule Qa-1. We demonstrate that HLA-E binds, although poorly, the peptide which binds to Qa-1 and that it also binds nonamer signal sequence-derived peptides from human MHC class I molecules. Using alanine and glycine substitutions, we could define primary anchor residues at positions 2 and 9 and secondary anchor residues at position 7 and possibly 3. 相似文献
46.
Andrew Williams 《The British journal of general practice》2002,52(484):940-941
47.
The involvement of excitatory amino acid (EAA) receptors in mediation of the toxic effects of cocaine was studied in male ICR mice. Cocaine HCl (90 mg/kg, IP) induced seizures in 95% and death within 24 h in 68% (n = 135) of the animals. There was a significant correlation (r = .54) between the time to onset of convulsions and the time to death in mice which died within 30 min of injection (n = 84). Pretreatment with selected EAA receptor antagonists 15 min prior to cocaine differentially blocked cocaine toxicity. Selective N-methyl-D-aspartic acid (NMDA) receptor antagonists (MK-801, dextrorphan, CPP) decreased both the incidence of seizures and mortality. A nonselective EAA antagonist, kynurenic acid, decreased lethality in doses which did not reduce convulsions. A similar action was observed following pretreatment with the selective kainic acid/AMPA receptor antagonist, GDEE. Antagonists at EAA receptors can provide significant protection against cocaine-induced toxicity. Moreover, the data provide evidence for the involvement of both NMDA and non-NMDA receptor subtypes in aspects of cocaine toxicity. 相似文献
48.
The present study was undertaken to define the response of plasma beta-endorphin immunoreactivity (ir-BE) to exercise of increasing intensity. Nineteen healthy males performed continuous exercise for 32 min on a cycle ergometer, comprised of 8-min bouts at %VO2max approximating 25, 50, and 75% of maximal exercise. Venous blood samples were collected before exercise (T = -20 and 0 min), during exercise (T = 8, 16, 24, and 32 min), and in recovery (T = +15, +30 min). Ir-BE in plasma was measured by radioimmunoassay using Immuno Nuclear assay kits. Plasma ir-BE level (pg X ml-1) was not altered from pre-exercise (18.3 +/- 1.3) after 8 min of exercise at 25 and 50% VO2max intensity; however, ir-BE rose significantly after 8 min of 75% VO2max work intensity (27.1 +/- 2.4) and was further elevated at maximal exercise (74.1 +/- 8.6). Ir-BE level remained elevated 15 min (60.9 +/- 8.1) and 30 min (35.2 +/- 5.2) post-exercise. The response pattern was further characterized by a significant (P less than 0.05) inter-individual variation, both at rest and during exercise; also, regression analysis indicated the ir-Be levels attained at maximal exercise were inversely related to the relative VO2max (ml X kg-1 X min-1) of the subject (predicted ir-BE = 248.2 - 3.39 VO2max; r = -0.397, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
49.
Steven R. Jensen M.D. Dawn R. Voegeli John C. McDermott Andrew B. Crummy 《Cardiovascular and interventional radiology》1986,9(4):202-204
Eight lymphatic fluid collections were drained percutaneously. There were no immediate or late complications. Seven patients
had follow-up; 1 required surgical drainage of a residual or recurrent lymphocele, and another had reaccumulated fluid in
a lymphocele which was detected on autopsy. The remaining lymphatic collections responded to percutaneous drainage. Percutaneous
drainage is safe and can be an effective tool in the management of lymphatic collections. 相似文献
50.
Bernard P Halloran Virginia L Ferguson Steven J Simske Andrew Burghardt Laura L Venton Sharmila Majumdar 《Journal of bone and mineral research》2002,17(6):1044-1050
To determine whether the mouse loses bone with aging and whether the changes mimic those observed in human aging, we examined the changes in the tibial metaphysis and diaphysis in the male C57BL/6J mouse over its life span using microcomputed tomography (microCT). Cancellous bone volume fraction (BV/TV) decreased 60% between 6 weeks and 24 months of age. Loss was characterized by decreased trabecular number (Tb.N), increased trabecular spacing (Tb.Sp), and decreased connectivity. Anisotropy decreased while the structure model index increased with age. Cortical bone thickness increased between 6 weeks and 6 months of age and then decreased continuously to 24 months (-12%). Cortical bone area (Ct.Ar) remained constant between 6 and 24 months. Fat-free weight reached a peak at 12 months and gradually declined to 24 months. Total mass lost between 12 and 24 months reached 10%. Overall, the age-related changes in skeletal mass and architecture in the mouse were remarkably similar to those seen in human aging. Furthermore, the rapid early loss of cancellous bone suggests that bone loss is not just associated with old age in the mouse but rather occurs as a continuum from early growth. We conclude that the C57BL/6J male mouse maybe a useful model to study at least some aspects of age-related bone loss in humans. 相似文献