全文获取类型
收费全文 | 2120篇 |
免费 | 131篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 33篇 |
儿科学 | 85篇 |
妇产科学 | 21篇 |
基础医学 | 350篇 |
口腔科学 | 19篇 |
临床医学 | 216篇 |
内科学 | 554篇 |
皮肤病学 | 36篇 |
神经病学 | 171篇 |
特种医学 | 189篇 |
外科学 | 214篇 |
综合类 | 31篇 |
预防医学 | 131篇 |
眼科学 | 10篇 |
药学 | 138篇 |
中国医学 | 8篇 |
肿瘤学 | 95篇 |
出版年
2022年 | 11篇 |
2021年 | 27篇 |
2020年 | 21篇 |
2019年 | 30篇 |
2018年 | 40篇 |
2017年 | 41篇 |
2016年 | 30篇 |
2015年 | 48篇 |
2014年 | 62篇 |
2013年 | 78篇 |
2012年 | 84篇 |
2011年 | 98篇 |
2010年 | 64篇 |
2009年 | 71篇 |
2008年 | 77篇 |
2007年 | 126篇 |
2006年 | 71篇 |
2005年 | 70篇 |
2004年 | 62篇 |
2003年 | 65篇 |
2002年 | 76篇 |
2001年 | 73篇 |
2000年 | 70篇 |
1999年 | 47篇 |
1998年 | 59篇 |
1997年 | 62篇 |
1996年 | 68篇 |
1995年 | 37篇 |
1994年 | 37篇 |
1993年 | 28篇 |
1992年 | 32篇 |
1991年 | 30篇 |
1990年 | 31篇 |
1989年 | 64篇 |
1988年 | 42篇 |
1987年 | 32篇 |
1986年 | 33篇 |
1985年 | 50篇 |
1984年 | 29篇 |
1983年 | 29篇 |
1982年 | 22篇 |
1981年 | 21篇 |
1980年 | 19篇 |
1979年 | 18篇 |
1978年 | 13篇 |
1977年 | 10篇 |
1976年 | 14篇 |
1975年 | 16篇 |
1974年 | 10篇 |
1973年 | 8篇 |
排序方式: 共有2301条查询结果,搜索用时 15 毫秒
21.
An autoradiographic method combined with a rosette technique was used to assess the bactericidal activity of individual control and inflammatory peritoneal macrophages (PM phi) in the presence or absence of expression of Fc receptor for IgG (FcR). There was a lack of FcR reactivity in a certain percentage of both categories of PM phi exposed to E. coli X43, a bacterium which is readily phagocytosed in the presence of specific antibody. Both rosetting and non-rosetting PM phi were capable of phagocytosing E. coli X43, but inflammatory PM phi showed a marked reduction in their capacity to ingest these bacteria compared with control PM phi. Once ingested the E. coli X43 were killed equally well by non-rosetting and rosetting control and inflammatory PM phi. 相似文献
22.
Error-related brain potentials are differentially related to awareness of response errors: evidence from an antisaccade task 总被引:19,自引:0,他引:19
The error negativity (Ne/ERN) and error positivity (Pe) are two components of the event-related brain potential (ERP) that are associated with action monitoring and error detection. To investigate the relation between error processing and conscious self-monitoring of behavior, the present experiment examined whether an Ne and Pe are observed after response errors of which participants are unaware. Ne and Pe measures, behavioral accuracy, and trial-to-trial subjective accuracy judgments were obtained from participants performing an antisaccade task, which elicits many unperceived, incorrect reflex-like saccades. Consistent with previous research, subjectively unperceived saccade errors were almost always immediately corrected, and were associated with faster correction times and smaller saccade sizes than perceived errors. Importantly, irrespective of whether the participant was aware of the error or not, erroneous saccades were followed by a sizable Ne. In contrast, the Pe was much more pronounced for perceived than for unperceived errors. Unperceived errors were characterized by the absence of posterror slowing. These and other results are consistent with the view that the Ne and Pe reflect the activity of two separate error monitoring processes, of which only the later process, reflected by the Pe, is associated with conscious error recognition and remedial action. 相似文献
23.
Linda P. Hunt Ashley W. Blom Gulraj S. Matharu Setor K. Kunutsor Andrew D. Beswick J. Mark Wilkinson Michael R. Whitehouse 《The Journal of arthroplasty》2021,36(2):471-477.e6
BackgroundTo determine unicompartmental (UKR) and total knee replacement (TKR) revision rates, compare UKR revision rates with what they would have been had they received TKR instead, and assess subsequent re-revision and 90-day mortality rates.MethodsUsing National Joint Registry data, we estimated UKR and TKR revision and mortality rates. Flexible parametric survival modeling (FPM) was used to model failure in TKR and make estimates for UKR. Kaplan-Meier estimates were used to compare cumulative re-revision for revised UKRs and TKRs.ResultsTen-year UKR revision rates were 2.5 times higher than expected from TKR, equivalent to 70 excess revisions/1000 cases within 10 years (5861 excess revisions in this cohort). Revision rates were 2.5 times higher for the highest quartile volume UKR surgeons compared to the same quartile for TKR and 3.9 times higher for the lowest quartiles respectively. Re-revision rates of revised TKRs (10 years = 17.5%, 95% confidence interval [CI] 16.4-18.7) were similar to revised UKRs (15.2%, 95% CI 13.4-17.1) and higher than revision rates following primary TKR (3.3%, 95% CI 3.1-3.5). Ninety-day mortality rates were lower after UKR compared with TKR (0.08% vs 0.33%) and lower than predicted had UKR patients received a TKR (0.18%), equivalent to 1 fewer death per 1000 cases.ConclusionUKR revision rates were substantially higher than TKR even when demographics and caseload differences were accounted for; however, fewer deaths occur after UKR. This should be considered when forming treatment guidelines and commissioning services. Re-revision rates were similar between revised UKRs and TKRs, but considerably higher than for primary TKR, therefore UKR cannot be considered an intermediate procedure. 相似文献
24.
Characterization of a culturable "Gastrospirillum hominis" (Helicobacter heilmannii) strain isolated from human gastric mucosa 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Andersen LP Boye K Blom J Holck S Norgaard A Elsborg L 《Journal of clinical microbiology》1999,37(4):1069-1076
Spiral organisms were isolated from an antral gastric mucosal biopsy specimen from a dyspeptic patient with gastritis. Only corkscrew-shaped organisms resembling "Gastrospirillum hominis" ("Helicobacter heilmannii") but no Helicobacter pylori-like organisms were seen in histological sections. H. pylori was not cultured from specimens from this patient. On the basis of biochemical reactions, morphology, ultrastructure, and 16S DNA sequencing, the isolated "G. hominis" was shown to be a true Helicobacter sp. very similar to Helicobacter felis and the "Gastrospirillum" but was separate from H. pylori. "G. hominis" is a pleomorphic gram-negative cork-screw-shaped, motile rod with 3 to 8 coils and a wavelength of about 1 micrometer. In contrast to H. pylori, it has up to 14 sheathed flagellar uni- or bipolar fibrils but no periplasmic fibrils. "G. hominis" grows under microaerobic conditions at 36 and 41 degrees C on 7% lysed, defibrinated horse blood agar plates within 3 to 7 days and can be subcultured under microaerobic but not under anaerobic conditions on media similar to those used for H. pylori and H. felis. The small translucent colonies were, in contrast to those of H. felis, indistinguishable from those of H. pylori. "G. hominis" is, like H. pylori and H. felis, motile, is oxidase, catalase, nitrite, nitrate, and urease positive, and produces alkaline phosphatase and arginine arylamidase. Like H. pylori and H. felis, it is sensitive to cephalothin (30-microgram disc), resistant to nalidixic acid (30-microgram disc), and sensitive to most other antibiotics. The 16S DNA sequence clusters "G. hominis" together with "Gastrospirillum," H. felis, Helicobacter bizzozeronii, Helicobacter salmonii, Helicobacter nemestrinae, Helicobacter acinonychis, and H. pylori. 相似文献
25.
Blom JH van Poppel H Marechal JM Jacqmin D Sylvester R Schröder FH de Prijck L 《European urology》1999,36(6):570-575
OBJECTIVE: The authors present demographic and surgical data from a randomized phase III trial, instituted by the EORTC Genitourinary Group in 1988, the aim of which was to assess whether complete lymph node dissection in conjunction with radical nephrectomy for renal cell cancer is more effective than radical nephrectomy alone. METHODS: Before surgery, the renal cell carcinoma was staged and judged to be nonmetastatic and resectable. The patients were randomized prior to surgery into those having radical nephrectomy combined with complete lymph node dissection or into those having radical nephrectomy alone. Postoperatively all patients were followed until progression of disease or death. RESULTS: Of the 772 randomized patients, 41 were not eligible. 383 had a complete lymph node dissection together with a radical nephrectomy. 389 had a radical nephrectomy alone. The complication rate did not differ significantly between the two groups. A complete lymph node dissection in 336 patients revealed absence of lymph node metastases in 325 of them. CONCLUSIONS: The present study shows that complete lymph node dissection does not add morbidity to the radical nephrectomy. After proper preoperative staging, the incidence of unsuspected lymph node metastases is low (3.3%). 相似文献
26.
27.
A mole of the EEG with waxing, waning and blocking alpha rhythm is described. One parameter is time dependent and simulates the "physiological alpha state' of the EEG generating network. A theoretically optimal detector of this state appears to be prescribed by the model and the statistics of the alpha state parameter. It minimizes the expected false decision rate. 相似文献
28.
Grubben MJ Boers GH Blom HJ Broekhuizen R de Jong R van Rijt L de Ruijter E Swinkels DW Nagengast FM Katan MB 《The American journal of clinical nutrition》2000,71(2):480-484
BACKGROUND: An elevated plasma homocysteine concentration is a putative risk factor for cardiovascular disease. Observational studies have reported an association between coffee consumption and plasma homocysteine concentrations. OBJECTIVE: We studied the effect of coffee consumption on plasma homocysteine in a crossover trial. We used unfiltered coffee so as to include the possible effects of coffee diterpenes, which are removed by filtering. DESIGN: Sixty-four healthy volunteers (31 men and 33 women) with a mean (+/-SD) age of 43 +/- 11 y were randomly assigned to 2 groups. One group (n = 30) drank 1 L unfiltered cafetière (French press) coffee daily for 2 wk. Such coffee is rich in the cholesterol-raising diterpenes kahweol and cafestol. The other group (n = 34) received water, milk, broth, tea, and chocolate drinks instead of coffee. After a washout period of 8 wk, both groups received the alternate intervention for another 2 wk. RESULTS: Consumption of 1 L unfiltered coffee/d for 2 wk significantly raised fasting plasma homocysteine concentrations by 10%, from 12.8 to 14.0 micromol/L. CONCLUSIONS: Unfiltered coffee increases plasma homocysteine concentrations in volunteers with normal initial concentrations. It is unclear whether the effect is caused by the cholesterol-raising diterpenes present exclusively in unfiltered coffee or by factors that are also present in filtered coffee. 相似文献
29.
Ionizing radiation is a carcinogen that induces oxidative DNA damage. 8-
Hydroxy-2'-deoxyguanosine (8-OHdG) is a relatively abundant, mutagenic
lesion that is widely regarded as a reliable index of oxidative DNA damage.
The purpose of this study was to examine the effects of X- radiation on
levels of 8-OHdG in the context of an experimental model for breast cancer
in which chronic radiation exposure has been shown to be carcinogenic in
Sprague-Dawley rats. A secondary objective of this study was to determine
if the use of phenol during DNA isolation affected the concentration of
8-OHdG subsequently measured. Our results indicate that a profoundly
carcinogenic dose of radiation induced a small but significant increase in
8-OHdG concentration in mammary gland DNA, and that the use of a
phenol-based versus a salt-based method of DNA isolation had no significant
impact on the levels of 8-OHdG detected in either control or irradiated
tissue.
相似文献
30.
van Kranen HJ; van Iersel PW; Rijnkels JM; Beems DB; Alink GM; van Kreijl CF 《Carcinogenesis》1998,19(9):1597-1601
The variation in colorectal cancer (CRC) incidence worldwide strongly
suggests a role for dietary influences. Based on epidemiological data,
protective effects of vegetables and fruit intake on CRC are widely
claimed, while other data indicate a possible increased CRC risk from
(higher) dietary fat intake. Therefore, we have investigated single and
interactive effects of dietary fat and a vegetable-fruit mixture (VFM) in
the ApcMin mouse, a mouse model for multiple intestinal neoplasia. In this
study, four different diets (A-D) were compared, which were either low in
fat (20% energy diets A/B) or high in fat (40% energy diets C/D). In
addition, 19.5% (wt/wt) of the carbohydrates in diets B and D were replaced
by a freeze-dried VFM. The diets were balanced so that they only differed
among each other in fat/carbohydrate content and the presence of specific
plant-constituents. Because the initiation of intestinal tumors in ApcMin
mice occurs relatively early in life, exposure to the diets was started in
utero. Without the addition of VFM, mice maintained at a high-fat diet did
not develop significantly higher numbers of small or large intestinal
adenomas than mice maintained at a low-fat diet. VFM added to a low-fat
diet significantly lowered multiplicity of small intestinal polyps (from
16.2 to 10.2/mouse, 15 animals/group), but not of colon tumors in male
ApcMin mice only. Strikingly, addition of VFM to female mice maintained on
a low-fat diet and to both sexes maintained on a high-fat diet
significantly enhanced intestinal polyp multiplicity (from 16.5 to 26.7
polyps/mouse). In conclusion, our results indicate that neither a lower fat
intake nor consumption of VFM included in a high-fat diet decreases the
development of polyps in mice genetically predisposed to intestinal tumor
development.
相似文献