全文获取类型
收费全文 | 143115篇 |
免费 | 14011篇 |
国内免费 | 655篇 |
专业分类
耳鼻咽喉 | 1915篇 |
儿科学 | 4220篇 |
妇产科学 | 2748篇 |
基础医学 | 16662篇 |
口腔科学 | 4790篇 |
临床医学 | 16224篇 |
内科学 | 30880篇 |
皮肤病学 | 1931篇 |
神经病学 | 13684篇 |
特种医学 | 4769篇 |
外国民族医学 | 1篇 |
外科学 | 21326篇 |
综合类 | 1712篇 |
现状与发展 | 12篇 |
一般理论 | 156篇 |
预防医学 | 13341篇 |
眼科学 | 3632篇 |
药学 | 8901篇 |
1篇 | |
中国医学 | 284篇 |
肿瘤学 | 10592篇 |
出版年
2023年 | 1665篇 |
2022年 | 1399篇 |
2021年 | 2958篇 |
2020年 | 2582篇 |
2019年 | 2856篇 |
2018年 | 4066篇 |
2017年 | 3294篇 |
2016年 | 3814篇 |
2015年 | 4244篇 |
2014年 | 5852篇 |
2013年 | 7816篇 |
2012年 | 9187篇 |
2011年 | 9780篇 |
2010年 | 6257篇 |
2009年 | 6495篇 |
2008年 | 8723篇 |
2007年 | 8968篇 |
2006年 | 8673篇 |
2005年 | 8550篇 |
2004年 | 7968篇 |
2003年 | 7338篇 |
2002年 | 7049篇 |
2001年 | 1550篇 |
2000年 | 1152篇 |
1999年 | 1586篇 |
1998年 | 1936篇 |
1997年 | 1692篇 |
1996年 | 1465篇 |
1995年 | 1320篇 |
1994年 | 1091篇 |
1993年 | 1041篇 |
1992年 | 835篇 |
1991年 | 752篇 |
1990年 | 673篇 |
1989年 | 638篇 |
1988年 | 624篇 |
1987年 | 601篇 |
1986年 | 516篇 |
1985年 | 586篇 |
1984年 | 636篇 |
1983年 | 609篇 |
1982年 | 779篇 |
1981年 | 676篇 |
1980年 | 579篇 |
1979年 | 399篇 |
1978年 | 379篇 |
1977年 | 391篇 |
1976年 | 322篇 |
1975年 | 297篇 |
1974年 | 301篇 |
排序方式: 共有10000条查询结果,搜索用时 21 毫秒
81.
Chronic hepatitis C in patients with persistently normal alanine transaminase levels. 总被引:2,自引:0,他引:2
Mitchell L Shiffman Moisés Diago Albert Tran Paul Pockros Robert Reindollar Daniele Prati Maribel Rodríguez-Torres Pilar Lardelli Steven Blotner Stefan Zeuzem 《Clinical gastroenterology and hepatology》2006,4(5):645-652
BACKGROUND & AIMS: Many patients with chronic hepatitis C virus (HCV) have persistently normal serum alanine transaminase (ALT) levels. We compared characteristics of chronic hepatitis C patients with patients with normal and elevated ALT levels using data from 3 randomized phase III trials of peginterferon alfa-2a (40 kDa). METHODS: The characteristics of 480 patients with normal ALT values (on >or=3 occasions without any increases in ALT level over a 6- to 18-month period) and 1993 patients with elevated ALT levels were compared. Sixty-eight of the 480 patients with normal ALT levels were randomized to no treatment and monitored for 72 weeks. RESULTS: More patients with normal ALT levels than patients with elevated ALT levels were women (59% vs 32%; P<.01). The serum HCV RNA titer was significantly lower in patients with normal ALT levels (P<.01 vs in patients with elevated ALT levels). Patients with normal ALT levels had significantly lower inflammation and fibrosis scores on liver biopsy examination than patients with elevated ALT levels, but almost two-thirds had portal fibrosis and 10% had bridging fibrosis. No correlation between baseline ALT activity, HCV RNA level, and liver histology was observed in patients with normal ALT levels. During the 72-week follow-up period, ALT activity elevated above the upper limit of normal in 53% of the untreated patients with normal levels of ALT. None became HCV RNA undetectable. CONCLUSIONS: Chronic hepatitis C patients with normal ALT levels should be evaluated in a similar manner as patients with elevated ALT levels because they are at risk for developing significant liver disease. The decision to treat with peginterferon alfa and ribavirin should be based on multiple factors, rather than on ALT levels alone. 相似文献
82.
83.
Edward R. Westrick MS Allan P. Shapiro PhD Peter E. Nathan PhD John Brick PhD 《Alcoholism, clinical and experimental research》1988,12(4):531-533
The present study demonstrates that alcohol-induced memory impairment can be attenuated by pretreatment with an oral tryptophan supplementation. These results provide support for the role of a brain serotonin deficit in this impairment and highlight the impact a dietary manipulation can have on a complex behavioral process. 相似文献
84.
Most prosthetic joint infections (PJI) are due to wound contamination at the time of surgery. Some infections occur due to the hematogenous spread of bacteria from distant sites of infection. A review of the literature fails to associate PJI with transient bacteremias from invasive dental procedures. Several authors have described conditions which, they believe, render patients with prosthetic joints more at risk for infection. Prosthetic joint patients with these "high risk" conditions have the same types of infecting organisms as other patients with PJI. This indicates that the infecting bacteria are from wound contamination or distant sites of infection and not related to dental procedure bacteremias. Based on this review, antibiotic prophylaxis is not indicated for patients with prosthetic joints when receiving invasive dental procedures, since there is no proven benefit and there are known risks involved with the use of antibiotics. However, the American Dental Association (ADA) and the American Academy of Orthopaedic Surgeons (AAOS), in an advisory statement, suggest prophylaxis for "high risk" patients. The ADA and AAOS recommend a single dose of amoxicillin, cephradine, or clindamycin when prophylaxis is selected. The dentist is ultimately responsible for making treatment recommendations for his or her patients. 相似文献
85.
86.
MR compatibility of Guglielmi detachable coils 总被引:6,自引:0,他引:6
87.
88.
Abraham Nudelman Yitschak Binnes Naomi Shmueli-Broide Yael Odessa J. Paul Hieble Anthony C. Sulpizio 《Archiv der Pharmazie》1996,329(3):125-132
Vinylogous (Groups III and V ) and acetylenologous (Group IV ) analogs of the classical β-adrenergic agents — stimulants and blockers — were prepared in order to evaluate the effect of degree of saturation, position of unsaturation and rigidity of the chain linking the aromatic ring and the amino containing functional group on biological activity. Derivatives from Group III , which represent 4-aryl-3-butenyl-2-ol-amine analogs of Group II , retained β1-adrenoceptor antagonist activity albeit substantially less potent (50–200-fold) than that possessed by their aryloxy counterparts. Consistent with the SAR for Group II compounds, substitution at position 2 of the aromatic ring yielded the most potent antagonists ( 5a, 5d, 5g ), with KB's ranging from 73–93 nM while 3,4-dichloro substitution ( 5e ) markedly reduced antagonist potency (KB = 2,400 nM). Agonist activity was also noted for 5b and 5d , suggesting that these compounds may be best classified as partial agonists. Representatives from Groups IV and V were inactive as antagonists at the β1-adrenoceptor confirming the importance of the spatial relationship between the hydroxyl and the amino nitrogen. 相似文献
89.
Veena Kumari Jeffrey A. Gray Philip J. Corr Owen F. Mulligan Paul A. Cotter Stuart A. Checkley 《Psychopharmacology》1997,129(3):271-276
The effects of an indirect dopamine-agonist, d-amphetamine, and a non-selective dopamine receptor antagonist, haloperidol, were investigated in normal male volunteers using
a between-subjects double-blind design in a procedural learning task, thought mainly to involve unconscious/automatic learning.
The results showed: (1) d-amphetamine facilitated response speed, whereas haloperidol inhibited it, in comparison to placebo; (2) the linear increase
in procedural learning corresponded with pharmacological manipulation of degree of dopaminergic activity, i.e. subjects given
haloperidol showed the least, and subjects given d-amphetamine the greatest, procedural learning. The implications of these findings are discussed in relation to investigation
of abnormalities of procedural learning processes in schizophrenia.
Received: 28 June 1996/Final version: 2 October 1996 相似文献
90.
A Decade of Change in Obesity Surgery 总被引:4,自引:0,他引:4
Edward E Mason MD PhD Shenghui Tang MS Kathleen E Renquist BS Dwight T Barnes Joseph J Cullen MD Cornelius Doherty MD James W Maher MD 《Obesity surgery》1997,7(3):189-197
Background: The International (formerly National) Bariatric Surgery Registry began collecting data in January 1986. The aim
of this study was to examine changes in the practice of surgical treatment of severe obesity that occurred during the decade
of 1986 through 1995, as observed in the IBSR data. Methods: All data submitted to the IBSR during the decade were transferred
to the IBM mainframe computer for analysis. Characteristics of operative type populations were compared over time using analysis
of variance (ANOVA) for age, body mass index (BMI), operative weight and Chi-square (χ2) test for gender. Results: There has been a steady increase over the decade in mean patient weight. The operations used have
changed from predominantly ‘simple’ operations to more frequent use of ‘complex’ operations. Within the categories of ‘simple’
and ‘complex’, an increase in the variety of operations occurred. As a group, patients with ‘simple’ operations have been
heavier, more often male and public pay patients than those who have undergone ‘complex’ operations. One year weight loss
was greater for Roux-en-Y gastric bypass (RGB) than vertical banded gastroplasty (VBG), but follow-up rates were too low to
study the relative merits of the operations used. The reported incidence of operative mortality and serious complications
(leak with peritonitis, abscess and pulmonary embolism) remained low. Conclusions: These observations and their implications
can be summarized in three statements which relate to action for improved patient care in the beginning of the new century:
(1) increasing weight of candidates for surgical treatment during this decade indicates the need for earlier use of operative
treatment before irreversible complications of obesity can develop; (2) low risk of obesity surgery, decreasing postoperative
hospital stay, and early weight control support the continued and increased use of surgical treatment; (3) continued widespread
use of both ‘simple’ and ‘complex’ operations with increased modifications of standard RGB and VBG procedures emphasizes the
need for standardized long-term data and analyses regarding both weight control and postoperative side-effects. 相似文献